imtoken钱包官方地址|dta
作者： imtoken钱包官方地址
2024-03-07 18:21:49
必读！热分析实用方法(3)——DTA - 知乎
必读！热分析实用方法(3)——DTA - 知乎切换模式写文章登录/注册必读！热分析实用方法(3)——DTA检测中心黄工未知成分分析，配方还原，检测分析，产品研发，产品技术 差热分析（DTA）（Differential Thermal Analysis）#01DTA原理差热分析（Differential Thermal Analysis—DTA）法是一种重要的热分析方法，是指在程序控温下，测量物质和参比物的温度差与温度或者时间的关系的一种测试技术。该法广泛应用于测定物质在热反应时的特征温度及吸收或放出的热量，包括物质相变、分解、化合、凝固、脱水、蒸发等物理或化学反应。物质在受热或冷却过程中，当达到某一温度时，往往会发生熔化、凝固、晶型转变、分 解、化合、吸附、脱附等物理或化学变化，并伴随有焓的改变，因而产生热效应，其表现为样品与参比物之间有温度差。在程序控制温度下，测量参比物和样品温差（△T）随温度（T）的变化。记录样品与参比物之间有温度差两者温度差与温度或者时间之间的关系曲线就是差热曲线（DTA曲线）。DTA与TG的区别在于测量值从质量变为温差。之所选择测试温差，是因为升温过程中发生的很多物理化学变化（比如融化、相变、结晶等）并不产生质量的变化，而是表现为热量的释放或吸收，从而导致样品与参比物之间产生温差。DTA能够发现样品的熔点、晶型转变温度、玻璃化温度等等信息。曲线图如下图所示：图中的纵坐标为温差，横坐标为温度或者时间。对于DTA曲线的分析主要有三部分：峰位、峰的形状和峰的个数。峰位用于判断发生变化的温度（比如相变温度、玻璃化温度、分解温度等）、峰的形状用于判断吸热还是放热，一般规定向上为放热、向下为吸热。每个峰都对应一种化学或物理变化。一般的差热分析装置由加热系统、温度控制系统、信号放大系统、差热系统和记录系统等组成。有些型号的产品也包括气氛控制系统和压力控制系统。现将各部分简介如下：1） 加热系统加热系统提供测试所需的温度条件，根据炉温可分为低温炉（<250℃）、普通炉、超高温炉（可达2400℃）；按结构形式可分为微型、小型，立式和卧式。系统中的加热元件及炉芯材料根据测试范围的不同而进行选择。2）温度控制系统温度控制系统用于控制测试时的加热条件，如升温速率、温度测试范围等。它一般由定值装置、调节放大器、可控硅调节器（PID-SCR）、脉冲移相器等组成，随着自动化程度的不断提高，大多数已改为微电脑控制，提高的控温精度。3）信号放大系统通过直流放大器把差热电偶产生的微弱温差电动势放大、增幅、输出，使仪器能够更准确的记录测试信号。4）差热系统差热系统是整个装置的核心部分，由样品室、试样坩埚、热电偶等组成。其中热电偶是其中的关键性元件，既是测温工具，又是传输信号工具，可根据试验要求具体选择。5）记录系统记录系统早期采用双笔记录仪进行自动记录，目前已能使用微机进行自动控制和记录，并可对测试结果进行分析，为试验研究提供了很大方便。6）气氛控制系统和压力控制系统该系统能够为试验研究提供气氛条件和压力条件，增大了测试范围，目前已经在一些高端仪器中采用。#02表征内容从差热图上可清晰地看到差热峰的数目、高度、位置、对称性以及峰面积。峰的个数表示物质发生物理化学变化的次数，峰的大小和方向代表热效应的大小和正负，峰的位置表示物质发生变化的转化温度。在相同的测定条件下，许多物质的热谱图具有特征性。因此，可通过与已知的热谱图的比较来鉴别样品的种类。理论上讲，可通过峰面积的测量对物质进行定量分析，但因影响差热分析的因素较多，定量难以准确。#03DTA的应用凡是在加热（或冷却）过程中，因物理-化学变化 而产生吸热或者放热效应的物质，均可以用差热分析法加以鉴定。其主要应用范围如下：1）含水化合物对于含吸附水、结晶水或者结构水的物质，在加热过程中失水时，发生吸热作用，在差热曲线上形成吸热峰。2）高温下有气体放出的物质一些化学物质，如碳酸盐、硫酸盐及硫化物等，在加热过程中由于CO2、SO2等气体的放出，而产生吸热效应，在差热曲线上表现为吸热谷。不同类物质放出气体的温度不同，差热曲线的形态也不同，利用这种特征就可以对不同类物质进行区分鉴定。3）矿物中含有变价元素矿物中含有变价元素，在高温下发生氧化，由低价元素变为高价元素而放出热量，在差热曲线上表现为放热峰。变价元素不同，以及在晶格结构中的情况不同，则因氧化而产生放热效应的温度也不同。如Fe2+在340~450℃变成Fe3+。4）非晶态物质的重结晶有些非晶态物质在加热过程中伴随有重结晶的现象发生，放出热量，在差热曲线上形成放热峰。此外，如果物质在加热过程中晶格结构被破坏，变为非晶态物质后发生晶格重构，则也形成放热峰。#01影响仪器仪表差热分析的主要因素1）气氛和压力的选择气氛和压力可以影响样品化学反应和物理变化的平衡温度、峰形。因此，必须根据样品的性质选择适当的气氛和压力，有的样品易氧化，可以通入N2、Ne等惰性气体。2）升温速率的影响和选择升温速率不仅影响峰温的位置，而且影响峰面积的大小，一般来说，在较快的升温速率下峰面积变大，峰变尖锐。但是快的升温速率使试样分解偏离平衡条件的程度也大，因而易使基线漂移。更主要的可能导致相邻两个峰重叠，分辨力下降。较慢的升温速率，基线漂移小，使体系接近平衡条件，得到宽而浅的峰，也能使相邻两峰更好地分离，因而分辨力高。但测定时间长，需要仪器的灵敏度高。一般情况下选择10℃/min～15℃/min为宜。3）试样的预处理及用量试样用量大，易使相邻两峰重叠，降低了分辨力。一般尽可能减少用量，最多大至毫克。样品的颗粒度在100目～200目左右，颗粒小可以改善导热条件，但太细可能会破坏样品的结晶度。对易分解产生气体的样品，颗粒应大一些。参比物的颗粒、装填情况及紧密程度应与试样一致，以减少基线的漂移。4）参比物的选择要获得平稳的基线，参比物的选择很重要。要求参比物在加热或冷却过程中不发生任何变化，在整个升温过程中参比物的比热、导热系数、粒度尽可能与试样一致或相近。常用三氧化二铝（α-Al2O3）或煅烧过的氧化镁或石英砂作参比物。如分析试样为金属，也可以用金属镍粉作参比物。如果试样与参比物的热性质相差很远，则可用稀释试样的方法解决，主要是减少反应剧烈程度；如果试样加热过程中有气体产生时，可以减少气体大量出现，以免使试样冲出。选择的稀释剂不能与试样有任何化学反应或催化反应，常用的稀释剂有SiC、Al2O3等。5）纸速的选择在相同的实验条件下，同一试样如走纸速度快，峰的面积大，但峰的形状平坦，误差小;走纸速率小，峰面积小。因此，要根据不同样品选择适当的走纸速度。现在比较先进的差热分析仪多采用电脑记录，可大大提高记录的精确性。除上述外还有许多因素，诸如样品管的材料、大小和形状、热电偶的材质以及热电偶插在试样和参比物中的位置等都是应该考虑的因素。发布于 2023-07-19 08:27・IP 属地广东差热分析热分析热分析仪器赞同 3添加评论分享喜欢收藏申请
【Notes】资产负债表观下的DTA和DTL - 知乎
【Notes】资产负债表观下的DTA和DTL - 知乎首发于Before the Law切换模式写文章登录/注册【Notes】资产负债表观下的DTA和DTL斯憨枕戈待旦 - four pillarsDTA和DTL是carrying value（按照会计准测规定的账面净值）和tax base（按照税法规定的计税基础）之间的差异。carrying value:账面净值（book value/carrying value=资产负债表上的科目的账面余额－相关备抵项目（包括累计折旧与摊销额，以及各类减值准备）后的净额。资产的账面净值是指企业在持续使用或最终出售该项资产时将会取得的经济利益的总和。负债的账面净值是企业预计在未来期间清偿该项负债时的经济利益流出。账面净值表示在会计中，即资产和负债的期末（初）余额。tax base:计税基础（tax base）是指资产负债表日后，资产或负债在计算未来应纳税所得额时根据税法规定还可以再抵扣【或应纳税】的剩余金额。资产的税基是指一项资产在未来期间可予扣除的金额，负债的税基是指账面净值在扣除之后的差额。计税基础表示在税法中处理资产和负债的期末（初）余额。[提问：book value和income之间的概念关系是什么? tax base和tax basis之间有区别吗？]tell DTL from DTA DTL和DTA所反映的会计和税法处理之间的差异是一种暂时性差异（temporary difference）, temporary difference和permanent difference之间的区别是，前者在会计期间内可以转回。DTL／A=|账面净值－计税基础|×税率，两者的值都表示的是一种绝对值，没有正负之分，因此不能通过值的本身来判断两者的区别。[理解：所以实际上DTL／A反映资产或负债从期初的预估税收结果与期末的实际税收结果差异的，如果预估的税收结果高于实际税收结果的是DTA因为企业未来会进行“多退”, 如果预估的税收结果低于实际税收结果的情况则是DTL因为企业未来需要进行“少补”。]DTA反映了可抵扣暂时性差异资产： 账面净值<计税基础 － “该资产未来期间产生的经济利益可以全部被税前抵扣”负债： 账面净值>计税基础 － “该负债使得企业未来可以抵扣的应纳税所得额为正”两者实质上都表示公司未来会享有抵扣税款的权利，现在是在多交税，因此这种与未来税收结果的差异可以被看作一种资产。DTL反映了应纳税暂时性差异资产： 账面净值>计税基础 － “该资产未来期间产生的经济利益无法全部被税前抵扣”负债： 账面净值<计税基础 － “该负债使得企业未来不能抵扣应纳税所得额，还要多交税金”两者实质上都表示公司未来需要缴纳更多税款，现在是在少交税，因此这种与未来税收结果的差异可以被看作一种负债。[提问：账面净值可以为负吗?不可以；是不是会计上的计税基础是去掉正负号以后的税法上的税基]编辑于 2019-10-04 21:09会计税务赞同 101 条评论分享喜欢收藏申请转载文章被以下专栏收录Before the LawIntl&US&CNTax结合
材料的表征与测试：DTA差热分析 - 知乎
材料的表征与测试：DTA差热分析 - 知乎切换模式写文章登录/注册材料的表征与测试：DTA差热分析优尔鸿信华南检测天津大学 工商管理硕士差热分析，differential thermal analysis，DTA定义：在程序控制温度下，测量物质和参比物的温度差和温度关系的一种技术。利用差热曲线的吸热或放热峰来表征当温度变化时引起试样发生的任何物理或化学变化。差热分析法（DTA）是基于试样和参比物间的温度差与温度的关系建立的分析方法。该方法在加热试样的同时，测量试样和参比物（即在所测量的温度范围内不发生任何热效应的物质）间的温度差。如试样发生吸热效应时，其温度TS将滞后于参比物的温度TR，记录温度差∆T（TS-TR）与温度的关系，从而得到DTA曲线。热分析-差热分析图差热分析仪的主要组成为：1.测量温度差的电路；2.加热装置和温度控制装置；3.样品架和样品池；4.气氛控制装置；5.记录输出系统。差热分析法中检测温度的常用装置是热电偶，它能方便且在线地取得试样和参比物的实际温度的正确读数。由于反应往往发生在试样的表面，而内部仍然未反应，这就造成试样的表面和内部之间总有一定的温度差，因此试样用量要尽可能少，并且颗粒大小和填装要尽可能均匀。在任何情况下，热电偶对于每次实验都必须精确定位。差热分析的测量原理是将试样与参比物置于相同炉温下，用差式热电偶测量二者的温差。试样无热效应发生时，热电偶无信号输出，差热分析曲线为直线。若有热效应发生，差热分析曲线偏离基线，随着吸热或放热速率的增加，温差增大，热效应结束，曲线回到基线。在差热分析曲线上形成一个峰，它代表某一温度下有吸热或放热效应发生。差热分析是在不断加热或冷却的环境下，使物质按照它固有的运动规律发生量变或质变，主要表现为吸热或放热，由此判断物质的内在变化。只要物质受热后有吸热或放热现象，就可用差热分析方法进行研究。责任编辑：张鹏辉资料来源：全国科学技术名词审定委员会 发布于 2022-03-01 11:01材料表征热分析差热分析赞同 7添加评论分享喜欢收藏申请
如何打开dta文件？ - 知乎
如何打开dta文件？ - 知乎首页知乎知学堂发现等你来答切换模式登录/注册文件如何打开dta文件？不是视频文件，是数据文件。关注者9被浏览242,604关注问题写回答邀请回答好问题 1添加评论分享3 个回答默认排序一吨Puppy每天都在努力学习 关注可以直接用python转成csv用excel打开dta文件：发布于 2021-04-04 16:24赞同 425 条评论分享收藏喜欢收起知乎用户dta应该是stata的数据文件格式，想打开自然可以用stata打开。另外免费软件中，用R也能直接读取，直接 read.dta 就能导入了，还能方便地转换为你想要的格式。发布于 2019-04-05 07:37赞同 126 条评论分享收藏喜欢收起
差示热分析_百度百科
析_百度百科 网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心收藏查看我的收藏0有用+10差示热分析播报讨论上传视频在程序控制温度下测定待测物质和参比物之间的温度差和温度关系的技术本词条由“科普中国”科学百科词条编写与应用工作项目 审核 。差示热分析（Differential Thermal Analysis，DTA）简称差热分析，是在程序控制温度下测定待测物质和参比物之间的温度差和温度关系的一种技术。物质在加热或冷却过程中的某一特定温度下往往会伴随吸热或放热效应的物理、化学变化，如晶型转换、沸腾、升华、蒸发、融化等物理变化以及氧化还原、分解、脱水和解离等化学变化。另有一些物理变化如玻璃化转变，虽无热效应发生，但热熔等某些物理性质也会发生改变。此时的物质不一定改变，但是温度是必定会变化的。差热分析就是在物质这类性质基础上建立的一种技术。差热分析法是对加热过程中所发生上述各种物理-化学现象做出精确的测定和记录。因此，被广泛应用于测定物质在热反应时的特征温度及吸收或放出的热量，也被广泛用于地质、冶金、石油、建材、化工等各个部门的研究及生产中。中文名差示热分析外文名Differential Thermal Analysis简 称差热分析英文简称DTA主要应用测定物质在热反应时的特征温度及吸收或放出的热量所属技术热分析技术目录1基本原理2结构简介3影响因素基本原理播报编辑图1具有不同自由电子束和逸出功的两种金属接触会产生电动势。如图1所示，当A金属丝和B金属丝焊接后组成闭合回路，如果两焊点的温度t1和t2不同就会产生温差电动势，闭合回路有电流流动，检流计指针偏转。温差电动势的大小与t1、t2 成正比。将两根不同的金属丝A和金属丝B以一端相焊接，置于需测温部位；另一端置于冰水环境中，并以导线与检流计相连，所得的温差电动势近似与热端的温度成正比，构成用于测温的热电偶。将两个反极性的热电偶串联起来，就构成了可用于测定两个热源之间温差的温差热电偶。将温差热电偶的一个热端插在被测试样品中，另一端插在待测温度区间不发生热效应的参比物中，将式样和参比物同时升温，测定升温过程中两者的温度差，这就是差热分析的基本原理 [1]。图2差热分析是在程序控制温度下，测量物质与参比物之间的温度差与温度关系的一种技术。差热分析曲线是描述样品与参比物之间的温差（△T）随温度或时间的变化关系。在差热分析试验中，样品温度的变化是由于相转变或反应的吸热或放热效应引起的。差热分析的基本原理如图2所示。结构简介播报编辑图3典型的差热分析装置如图3所示 [2]。基本由以下几部分组成：(1)温度程序控制单元使炉温按给定的程序方式（升温、降温、恒温、循环)以一定速度上升、下降或恒定。(2)差热放大单元用以放大温差电势，由于记录仪量程为毫伏级，而差热分析中温差信号很小，一般只有几微伏到几十微伏，因此差热信号须经放大后再送入记录仪中记录。(3)记录单元由双笔自动记录仪将测温信号和温差信号同时记录下来。在进行差热分析过程中，如果升温时试样没有热效应，则温差电势应为常数，差热曲线为一直线，称为基线。但是由于两个热电偶的热电势和热容量以及坩埚形态、位置等不可能完全对称，在温度变化时仍有不对称电势产生。此电势随温度升高而变化，造成基线不直，这时可以用斜率调整线路加以调整。方法是：坩埚内不放参比物和样品，将差热放大量程置于100μV，升温速度置于10℃/min，用移位旋钮使温差记录笔处于记录纸中部，这时记录笔应画出一条直线。在升温过程中如果基线偏离原来的位置，则主要是由于热电偶不对称电势引起基线漂移。待炉温升到750度时，通过斜率调整旋钮校正到原来位置即可。此外，基线漂移还和样品杆的位置、坩埚位置、坩埚的几何尺寸等因素有关。影响因素播报编辑差热分析操作简单，但在实际工作中往往发现同一试样在不同仪器上测量，或不同的人在同一仪器上测量，所得到的差热曲线结果有差异。峰的最高温度、形状、面积和峰值大小都会发生一定变化。其主要原因是因为热量与许多因素有关，传热情况比较复杂所造成的。一般说来，一是仪器，二是样品。虽然影响因素很多，但只要严格控制某种条件，仍可获得较好的重现性 [2]。气氛和压力的选择气氛和压力可以影响样品化学反应和物理变化的平衡温度、峰形。因此，必须根据样品的性质选择适当的气氛和压力，有的样品易氧化，可以通入N2、Ne等惰性气体。升温速率的影响和选择升温速率不仅影响峰温的位置，而且影响峰面积的大小，一般来说，在较快的升温速率下峰面积变大，峰变尖锐。但是快的升温速率使试样分解偏离平衡条件的程度也大，因而易使基线漂移。更主要的可能导致相邻两个峰重叠，分辨力下降。较慢的升温速率，基线漂移小，使体系接近平衡条件，得到宽而浅的峰，也能使相邻两峰更好地分离，因而分辨力高。但测定时间长，需要仪器的灵敏度高。一般情况下选择8℃/ min～12℃/ min为宜。试样的预处理及用量试样用量大，易使相邻两峰重叠，降低了分辨力。一般尽可能减少用量，最多大至毫克。样品的颗粒度在100目～200目左右，颗粒小可以改善导热条件，但太细可能会破坏样品的结晶度。对易分解产生气体的样品，颗粒应大一些。参比物的颗粒、装填情况及紧密程度应与试样一致，以减少基线的漂移。参比物的选择要获得平稳的基线，参比物的选择很重要。要求参比物在加热或冷却过程中不发生任何变化，在整个升温过程中参比物的比热、导热系数、粒度尽可能与试样一致或相近。常用- Al2O3或煅烧过的氧化镁（MgO）或石英砂作参比物。如分析试样为金属，也可以用金属镍粉作参比物。如果试样与参比物的热性质相差很远，则可用稀释试样的方法解决，主要是减少反应剧烈程度；如果试样加热过程中有气体产生时，可以减少气体大量出现，以免使试样冲出。选择的稀释剂不能与试样有任何化学反应或催化反应，常用的稀释剂有SiC、铁粉、Fe2O3、玻璃珠Al2O等。纸速的选择在相同的实验条件下，同一试样如走纸速度快，峰的面积大，但峰的形状平坦，误差小；走纸速率小，峰面积小。因此，要根据不同样品选择适当的走纸速度。不同条件的选择都会影响差热曲线，除上述外还有许多因素，诸如样品管的材料、大小和形状、热电偶的材质以及热电偶插在试样和参比物中的位置等。市售的差热仪，以上因素都已固定，但自己装配的差热仪则需要考虑这些因素 [3]。新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号 京公网安备110000020000TG、DTA、DSC —— “ 热火 ” 三巨头 - 哔哩哔哩
TA、DSC —— “ 热火 ” 三巨头 - 哔哩哔哩 TG、DTA、DSC —— “ 热火 ” 三巨头研理云讲坛关注专栏/TG、DTA、DSC —— “ 热火 ” 三巨头TG、DTA、DSC —— “ 热火 ” 三巨头
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关注热分析是科研表征中常见的手段。所谓热分析，指通过控制样品温度的改变，来分析其相应物理化学性质的改变。最为常见的热分析手段有三种热重分析（TG）、差热分析（DTA）和差示扫描量热法（DSC）。具体分析和讲解如下：1. 如何正确选择热分析方法？三种热分析方法各有所长，可以单独使用、也可以联合使用。具体如何选择，我们首先从定义出发，了解这些表征手段。TG：在程序控温下，测量样品的质量（m）随温度的变化。如果你需要知道，样品在升温或者降温过程中，样品质量的变化（比如吸附、脱附、分解等），请选择TG。比如工业催化剂中常会有积碳现象，通过TG表征可以确定积碳量。DTA：在程序控制温度下，测量参比物和样品温差（△T）随温度（T）的变化。DTA与TG的区别在于测量值从质量变为温差。之所选择测试温差，是因为升温过程中发生的很多物理化学变化（比如融化、相变、结晶等）并不产生质量的变化，而是表现为热量的释放或吸收，从而导致样品与参比物之间产生温差。DTA能够发现样品的熔点、晶型转变温度、玻璃化温度等等信息。DSC: 在程序控制温度下，测量给于参比物和给予样品的能量之差（△Q）随温度（T）的变化。在整个测试过程中，样品和参比物温差控制在极小的范围内。当样品发生物理或者化学变化时，控温装置将输入一定功率能量，以保持温度平衡。可以简单的将DSC看成是DTA的升级版。DSC也确实是从DTA发展而来。传统的DTA仪器因为样品池材质的关系，只能测温差，无法准备测量热和焓的变化。后期通过改变材质和结构，使得从温差转变为能量差成为可能（热流型）。最后又出现一种直接测量输入热量差的DSC(功率补偿型)。DSC的优点在于灵敏度高、可以定量测量焓、比热容等物理量。2. 数据如何分析？TG：典型的TG图如下图1所示：图 1其中最重要的信息是失重的温度点和失重的比例。根据你所测试材料的性质和这些温度点、失重比例，可以推测所发生的物理化学变化。比如100 - 150 摄氏度之间常对应物理吸附的水。200 - 350摄氏度范围的失重常对应有机物的分解。DTA：曲线图如下图2所示：图 2图中的纵坐标为温差，横坐标为温度或者时间。对于DTA曲线的分析主要有三部分：峰位、峰的形状和峰的个数。峰位用于判断发生变化的温度（比如相变温度、玻璃化温度、分解温度等）、峰的形状用于判断吸热还是放热，一般规定向上为放热、向下为吸热。每个峰都对应一种化学或物理变化。DSC: 如图3.图3从形状来看，DSC曲线和DTA很相似，但纵坐标不同。DSC图中纵坐标热流量（单位为mW或者mJ/S）。从积分峰面积就能算出焓变。如果参比物比热容已知还可以算出样品的比热容。在实际应用中TG常和DTA或者DSC连用。3. 测试中的注意事项在进行热分析测试时，需要注意三个方面：1.升温速率，升温速率不易过快。否则会导致基线不稳，温度测试不准确等问题。一般选择在10 - 20 摄氏度/min。2.气氛的选择：这需要根据要求选择。比如需要排除O2的干扰，则可以选择N2气氛。还可以选择还原性气氛。3. 加盖与否：a. 对于物理效应(熔融、结晶、相变等)的测试或偏重于DSC的测试，通常选择加盖。对于未知样品，出于安全性考虑，通常选择加盖。b. 对于气固反应(如氧化诱导期测试或吸附反应)，使用敞口坩埚(不加盖)。c. 对于有气体产物生成的反应(包括多数分解反应 )或偏重于TG的测试，在不污染损害样品支架的前提下，根据反应情况与实际的反应器模拟，进行加盖与否的选择。对于液相反应或在挥发性溶剂中进行的反应，若反应物或溶剂在反应温度下易于挥发，则应使用压制的Al坩埚(温度与压力较低)或中压、高压坩埚(温度与压力较 高)。对于需要维持产物气体分压的封闭反应系统中的反应同样如此。{加盖与否内容摘自《现代催化研究方法》}4. 实例分析：图 4图4为WZrOx复合催化剂的TG和DSC图。150度之前的质量损失（TG图）为催化剂表面吸附水的脱除。310 - 340 C为有机大分子的分解，对应DSC图中的α放热峰。350度之后，TG线中没有任何质量损失。DSC曲线上的β放热峰对应ZrO2的结晶峰。结合其他表征，作者将γ峰归结为催化剂中形成很细小的W-ZrO2 Cluster。本文禁止转载或摘编
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如何通俗易懂地理解递延税项（Deferred Tax）？ - 知乎
如何通俗易懂地理解递延税项（Deferred Tax）？ - 知乎首页知乎知学堂发现等你来答切换模式登录/注册会计财报税法如何通俗易懂地理解递延税项（Deferred Tax）？本题已加入知乎圆桌 » 注册会计师之路 ，更多「注册会计师」讨论欢迎关注。 每次在财务书中看到此项都觉得理解起来比较复杂和混乱。 所以求业内人士可否深…显示全部 关注者2,108被浏览520,628关注问题写回答邀请回答好问题 52 条评论分享50 个回答默认排序MrToyy2013 年度新知答主 关注递延税项指企业所得税。递延税项是会计当中“配比原则”的经典体现。配比原则要求，当期的收入要与成本、费用配比。不能只确认收入，不确认相关的成本、费用；也不能只确认成本或费用而不确认相关的收入。此举是为了尽量减少会计操纵，稳定公司的毛利率、净利率。那么，递延税项的存在，就是为了将应当当期负担的所得税与当期的收入、成本费用进行配比。这里有一个疑问，为什么需要配比呢？难道企业不就应该按其利润缴纳企业所得税吗？这是源于税法与会计准则的差异。税法因为是规范纳税，所以企业自主空间很小；会计准则更多的满足各种不同行业的需求，企业自主空间比税法更大。在到税务局缴税的时候，企业会根据税法规定计算应缴纳的税款；在财务报表上，企业会根据实际的经营利润计算应缴纳的税款。由于企业在会计核算上与税法规定上有差异，导致利润表上应计的税款与实际缴纳的税款有差异。这个差异，就是递延税项。其中，实际缴纳的多与利润表上的，就是递延所得税资产，表是以后可以少交所得税；反之就是递延所得税负债，表示以后会多交所得税。发布于 2013-12-24 15:58赞同 20515 条评论分享收藏喜欢收起Jerry Zhang 关注这是个好长的问题，喝口水先！！以天朝为例，会计的记账方式和税务局认可的利润表科目记录方式之间是存在差异的，而这个差异就会导致：1. 有些费用公司账面记录了，但是税务局并不承认，导致公司无法税前抵扣，这种情况叫做永久性差异（permanent differences）2. 有些费用公司账面记录了，但是税务局认为这个事实当期并没发生，所以当期没办法抵扣，等到你实际发生这件事情的时候才让你抵扣，这种情况叫做暂时性差异（temporary differences）在上述两种情况下面，第一种是不会产生递延税项的（因为税务局到死都不会让你抵扣这部分费用的），第二种由于费用确认在不同的会计年度而产生的暂时性差异才会产生递延税项。至于是DTA还是DTL，接下来继续：1. DTA：如果有费用当期发生，税局当期不认，非要你以后认，这种情况下表示税局给了你一个以后抵扣费用的权利，相应的未来缴纳的所得税款就会降低，所以恭喜你，可以确认一笔DTA啦，比较常见的会产生DTA的项目有：当期确认的应收款项坏账准备（这笔坏账实际还没发生，可能只是根据会计政策/会计估计的要求确认），当期确认的存货跌价准备（与AR provision同理），超过税务局规定确认的固定资产折旧，可以用于未来期间抵扣的累计亏损额等等2. DTL：DTL的情况就刚好与DTA相反了，税局当期让你抵扣的费用超出了会计账面记录的费用，这种情况下未来你要把这部分超额抵扣的费用吐出来，相应的未来缴纳的所得税款就会增加，这个时候就得确认DTL啦，比较常见的是：当期税局允许抵扣的固定资产的折旧额超出了会计账面记录的折旧金额（其他暂时没想到）。我觉得天朝税局的总的原则是晚交不如早交，所以DTA出镜的机会远大于DTL啦。发布于 2013-12-24 15:44赞同 59227 条评论分享收藏喜欢
dta类型的数据文件怎么用spss打开？ - 知乎
dta类型的数据文件怎么用spss打开？ - 知乎首页知乎知学堂发现等你来答切换模式登录/注册数据分析dta类型的数据文件怎么用spss打开？下了stattransfer，可是没找到输入转换的dta数据类型，不知道哪里不对。求教。想把dta转成spss可读的sav格式，怎么解决？关注者12被浏览66,107关注问题写回答邀请回答好问题 1添加评论分享3 个回答默认排序今儿个学习数据分析民工 关注不邀自来。我的老粉都知道，比起SPSS，我更推荐数据分析小白使用SPSSAU分析数据。一方面，spssau的操作步骤极其简单，两步即可输出结果；另一方面，spssau支持多格式数据导入，其中包含dta类型的数据文件，极其方便、快捷。一、导入数据进入SPSSAU，点击上传文件即可，支持多格式导入：spssauEXCEL格式(包括csv、 xls 和 xlsx )， SPSS格式(SAV)，以及Stata格式（dta）和SAS格式（sas7bdat）数据。另外，更支持问卷星、问卷网、腾讯问卷、SPSS的数据导入①问卷星用户，下载数字格式数据如下：②问卷网用户，下载CSV格式(压缩包里面的"All_Data_Original")或者SAV格式数据均可直接上传，如下：③ 腾讯问卷用户，下载数字格式数据为“统计”->“回收数据”->“导出”->“导出编码数据(.csv)”或者“导出SPSS数据(.sav)”。【建议“导出SPSS数据(.sav)”。】④如果是SPSS格式(sav)数据，直接上传即可:如果上传SPSS格式后显示为乱码（但SPSS软件打开却显示正常），解决办法为：任意修改SPSS数据的一个标题后保存，然后上传即可。二、数据清理数据上传后，要立即完成数据清理工作，这步操作将极大地降低数据分析产生错误的概率。可能涉及到以下数据清理工作，包括：标题修改：对标题进行修改或者删除处理；数据标签：标识定类数据时，数字代表的意义；数据编码：对数字进行组合，比如反向题，数据选项组合等；生成变量：比如多个变量标识 1个变量时，可使用“平均值”，还有其它比如虚拟变量，求和，标准化，中心化，归一化，取对数等 10多种处理。那么，如何在SPSSAU中实现数据清理呢？具体查看方式如下，首先进入spssau官网，在左侧功能栏中找到【数据处理】即可。小伙伴们可以根据自己所需选择对应的数据处理方式哦~三、总结Spssau操作极其简单，支持多格式数据导入。此外，官网更为用户提供了案例数据库，小白可以根据己需调整数据格式，如下图所示：往期文章推荐：一文理清量表类/非量表类问卷分析思路！带你入门三：别再问如何自学SPSS了！懂了这些你就入门了！发布于 2022-04-07 16:02赞同 1添加评论分享收藏喜欢收起爱Econ爱生活Research is hard! 关注看题主的需求，需要使用stattransfer进行格式转换。这一软件的安装可以参考我的文章https://zhuanlan.zhihu.com/p/112449521安装好以后，选择输入文件格式为stata，输出为spss for Windows，点击左下方transfer就得到spss可以打开的sav文件了。希望有所帮助！觉得可以请给在下点个赞！发布于 2020-03-11 15:56赞同 2510 条评论分享收藏喜欢收起
热重-差热分析（TG-DTA）数据分析及作图法
热重-差热分析（TG-DTA）数据分析及作图法
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热重-差热分析（TG-DTA）数据分析及作图法
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在《热重数据怎么用Origin作出画图》和《Origin软件中热重曲线的作图方法》中分别介绍了热重曲线和《微商热重曲线的作图方法》，一些读者留言希望了解热重-差热分析（TG-DTA）的数据分析及作图相关的内容。因此，在本文中将介绍常用的TG-DTA法的数据分析及作图相关的内容。
1. TG-DTA方法简介
热重-差热分析 （thermogravimetric-differential thermal analysis，简称TG-DTA）是在程序控温和一定气氛下，同时测量试样的质量和输入到试样与参比物的温度差随温度或时间关系的技术。TG-DTA是一种常用的同时联用的热分析联用技术，通常笼统地称为同步热分析法（同步热分析有时也用来指TG-DSC）。
TG-DTA技术将TG与DTA结合为一体，在同一次测量中利用同一样品可同步得到试样的质量变化及试样与参比物的温度差的信息。常用的TG-DTA仪主要有水平式和上皿式两种结构形式。测试时将装有试样和参比物的坩埚置于与称量装置相连的支持器组件中，在预先设定的程序控制温度和一定气氛下对试样进行测试，在测试过程中通过天平实时测定试样的质量，同时通过支持器组件的温差热电偶测量试样与参比物的温度差随温度或时间的变化信息，获得TG-DTA曲线。
2. TG-DTA曲线分析
由TG-DTA曲线可以得到样品的质量和热效应的变化信息，在实际的数据分析和作图中通常将TG曲线和DTA曲线放在一起进行综合分析（图1）。图1中的绿色曲线为TG曲线，蓝色曲线为DTA曲线，图中当TG曲线的质量发生变化时（第一个台阶对应于失去一分子结晶水的过程，第二个质量变化台阶对应于失去一分子CO的过程，第三个质量变化台阶对应于失去一分子CO2的过程）。DTA曲线中对于这个质量变化过程分别表现出了不同的热效应，分别对应于每一个质量变化过程。
图1 一水草酸钙的TG-DTA曲线
在《Origin软件中热重曲线的作图方法》和《微商热重曲线的作图方法》中均已指出，为了便于比较样品在实验过程中的质量变化程度，通常需要对初始质量进行归一化处理。同样地，在对DTA曲线进行数据分析时也应对初始质量进行归一化处理。图1中，由于DTA曲线测量的是样品相对参比的温度差，因此在DTA曲线中纵坐标所对应的测量的物理量为温度差（单位为℃/mg或者K/mg）。需要特别指出，有些仪器得到的软件中所导出的DTA曲线的纵坐标所对应的测量的温度差的单位为μV/mg，这是由于软件中没有将热电偶测量的电势差的信号转换为温度单位引起的（图2）。
图2 DTA曲线的纵坐标所对应的测量的温度差的单位为μV/mg
由于DTA测量的为试样相对于参比物的温度差，该值为相对值，在进行数据分析时通常并不影响对一个过程的热效应的分析结果。
3. 在作图软件中TG-DTA曲线的作图方法
下面以Origin软件为例来介绍TG-DTA曲线的作图方法。
首先将由仪器所附带的分析软件导出的ASCII格式的.txt文件或者.csv导入到Origin软件中，导入后的界面如图3所示。
图3
然后，将温度列设定为X轴、将质量（第3列）和温度差（第4列为uV，第5列为℃，本例中以℃为例，故使用第5列的数据）数据进行归一化处理，并删去前三十行与实验相关的一些参数信息、命名每一栏所代表的的物理量，界面如图4所示。
图4
选中表格中的B、C、E列（图5）并点击图Double-Y图标（图6），即可以得到TG-DTA曲线，如图7所示。
图5
图6
图 7
点击图中的曲线可以改变曲线的大小和颜色，点击图中的数字和图题也可以进行相应的编辑工作。
有时需要将DTG曲线加入到TG-DTA曲线中进行综合分析，此时在图中分别出现了TG曲线、DTA曲线和DTG曲线。图4中的F列为微商重量数据，作图时同时选中B、C、E、F列（图8）。然后，点击Double-Y图标中的3Ys-Y-YY选项（图9），即可以得到TG-DTA-DTG曲线，如图10所示。图10中，黑色曲线对应于TG曲线、红色曲线对应于DTA曲线、蓝色曲线对应于DTG曲线。点击图中的曲线可以改变曲线的大小和颜色，点击图中的数字和图题也可以进行相应的编辑工作。
图8
图 9
图10
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China's Double Taxation Avoidance Agreements
Global investors often find themselves in an unfavorable position of having to face being double taxed – taxed by two different countries on the same income – unless there is a double tax avoidance agreement in place. For example, a company might be subject to taxes in its country of residence and also in the countries where it raises income through foreign investments for the provision of goods and services.
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WATCHMaximize Profits in Your Dividend Repatriation by Leveraging the PRC-HK DTAThis video is unavailable in your region. Please enable VPN to view
Double Tax Avoidance Agreements treaties effectively eliminate double taxation by identifying exemptions or reducing the amount of taxes payable.
It is, therefore, extremely worthwhile for foreign investors to be aware of which double taxation avoidance agreements (DTAs) between China and other countries might be applicable to their situation, as well as understand how these agreements are applied.
DTAs not only provide certainty to investors regarding their potential tax liabilities but also act as a tool to create tax-efficient international investments.
List of Double Tax Avoidance Agreements
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As of 2022, China has signed DTAs with 110 countries or regions. Investors may check the table below and determine whether they are tax residents of a country that has an effective DTA with China.
Countries (Regions) with Signed DTAs with China (as of September 2022)
A-C
D-J
H-K
L-N
O-S
T-Z
Argentina*
Cambodia
Hong Kong
Laos
Oman
Tajikistan
Angola*
Canada
Hungary
Latvia
Pakistan
Taiwan*
Albania
Chile
Iceland
Lithuania
Papua New Guinea
Thailand
Algeria
Congo*
India
Luxembourg
Philippines
Trinidad & Tobago
Armenia
Croatia
Indonesia
Macao
Poland
Tunisia
Australia
Cuba
Iran
Macedonia
Portugal
Turkey
Austria
Cyprus
Ireland
Malaysia
Romania
Turkmenistan
Azerbaijan
Czech Republic
Israel
Malta
Russia
Ukraine
Bahrain
Denmark
Italy
Mauritius
Saudi Arabia
United Arab Emirates
Bangladesh
Ecuador
Jamaica
Mexico
Serbia & Montenegro
United Kingdom
Barbados
Egypt
Japan
Moldova
Seychelles
United States
Belarus
Estonia
Katar
Mongolia
Singapore
Uzbekistan
Belgium
Ethiopia
Kazakhstan
Morocco
Slovakia
Uganda*
Bosnia-Herzegovina
Finland
Kenya*
Nepal
Slovenia
Venezuela
Botswana
France
Korea (ROK.)
Netherlands
South Africa
Vietnam
Brazil
Gabon*
Kuwait
New Zealand
Spain
Zambia
Brunei
Georgia
Kyrgyzstan
Nigeria
Sri Lanka
Zimbabwe
Bulgaria
Germany
Norway
Sudan
Greece
Sweden
Switzerland
Syria
* Signed but not in effect at the time of writing.
Also Read
Gain Insight into China's Tax Avoidance Policies
Who do DTAs apply to?
DTAs apply to residents (individuals or companies) of the countries or regions who are parties to the agreement.
The DTA applicant must be a tax resident of a country that has an effective DTA with China, and the applied benefits must qualify for tax exemption or reduction as stipulated by the DTA.
Applying for DTA benefits
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Non-resident taxpayers are no longer required to submit the relevant documents to the tax bureau when applying for the DTA benefits. Rather, they can determine whether they are qualified for the tax benefits by themselves, enjoy the preferential tax rates when filing for relevant taxes (or when withholding taxes by a withholding agent), and retain the required documents by themselves for future inspection from the tax bureau in charge.
Materials to be retained for future inspection include:
Tax resident identity proof issued by the tax authorities of the treaty contracting party to prove the taxpayer’s obtaining tax resident status in the current year or the preceding year; for those claiming benefits under the international transport clause of a treaty or benefits under an international transport agreement, the tax resident identity proof may be replaced by a certificate proving that the taxpayer satisfies the identity stipulated in the treaty or agreement;
Ownership proof materials such as contract, agreement, board resolution or shareholders’ meeting resolution, proof of payment, etc., which are related to the income derived;
For those claiming benefits under dividend, interest, or royalty clauses under a treaty, the relevant materials proving “beneficiary owner” identity shall be retained; and
Any other materials for which the non-resident taxpayer deems to be able to prove its satisfaction of criteria for claiming treaty benefits.
Non-resident taxpayers shall bear legal liability for the veracity, accuracy, and legitimacy of the information completed in the Information Report on Non-resident Taxpayers Claiming Treaty Benefits and the documents retained for future inspection.
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A Chinese translation will be required where the submitted documents are in foreign languages. The applicant shall be responsible for the accuracy and integrity of the Chinese translation.
The non-resident taxpayer or the withholding agent should possess both original copies and photocopies of the relevant materials for submission or inspection by the tax authorities in charge.
Permanent Establishment and Beneficial Owner status
Among other details, permanent establishment (PE) and beneficial owner status are of critical importance for understanding the workings of DTAs.
Permanent establishment (PE)
A foreign company can be deemed to have a PE in China if:
It has an establishment or a place of business in China (Fixed place PE);
It has a building site, a construction, assembly, or installation project, or related supervisory activities that last for a certain period of time (Construction PE);
It appoints an agent in China to conclude contracts or accept orders in China (Agent PE); or
It has employees working in China for a certain period of time (Service PE).
If a PE is constituted under the DTA, the foreign entity will be liable for tax over the income earned in China or income that is attributable to its presence in China.
A PE can be defined as a fixed place where the business of an enterprise is carried out in a given country. It is a key concept for the applicability of DTAs.
A non-resident enterprise can only claim exemption from its taxes payable if its establishment or premises in China do not constitute a PE pursuant to the PE article under the relevant DTA.
Tax implications of a PE
If an establishment or venue of a non-resident enterprise constitutes a PE in China, it will be subject to a 25 percent tax on all of its China-sourced income, as well as non-China-sourced (worldwide) income that is deemed to have an actual connection to the PE.
The general principles on PE taxation, as laid out in Article 7 of most DTAs, clarify the following:
Only the profits of a non-resident enterprise attributable to its PE in China are taxable in China;
When determining the profits of a PE, transactions between the non-resident enterprise and the PE are treated as transactions between independent parties;
Expenses incurred in the business of a PE, including general and administrative expenses allocated from the non-resident enterprise, are deductible; and
Royalty service fees that have substantial connections with a PE will be taxed as the profit of the PE, incurring the 25 percent tax payable rather than the reduced or exempted rates under the DTA’s royalty provision.
Below is the range of deemed profit rates that the tax authorities will apply depending on the nature of the non-resident enterprise’s business:
Deemed Profit Rates of Different Non-resident Enterprises
Types of business
Deemed profit rate
Construction projects, design, and consulting services
15% - 30%
Management services
30% - 50%
Other services or operating activities other than service
No less than 15%
Beneficial owner
It is important to understand who can be regarded as a beneficial owner when applying for DTA treatments on dividend, interest, and royalty clauses. Beneficial owner refers to an individual, company, or any other group having the ownership and right of control over the income or the right or property derived from the income. A beneficial owner should be engaged in actual operating activities; therefore, an agent or a designated payee does not constitute a beneficial owner.
Unfavorable factors for beneficial owner assessment
To determine the “beneficial owner” status of an applicant who needs to enjoy the tax treaty benefits, a comprehensive analysis should be carried out, taking into account the actual conditions of the specific case.
Among others, there are some factors regarded as “unfavorable” during the assessment:
The applicant is obligated to pay 50 percent or more of the income to a resident of a third country (region) within 12 months from receipt of the income. “Obligated” shall include agreed obligations and de facto payment even though there is no agreed obligation;
The business activities undertaken by the applicant do not constitute substantive business activities like manufacturing, sales and marketing, and management (including Investment holding management);
The counterparty country (region) of the tax agreement does not levy tax or exempts tax on the relevant income, or the actual levy rate is very low;
Aside from loan contracts upon which interest is derived and paid, there exist other loan or deposit contracts between the creditor and a third party which are similar in their terms of amount, interest rate, and date of execution, etc.; and
Aside from contracts for the transfer of copyrights, patents, proprietary technologies, and other usage rights based upon which royalties are derived and paid, there exist contracts between the applicant and a third party pertaining to the transfer of copyrights, patents, proprietary technologies, and other usage rights or ownership.
“Safe harbor rule” in beneficial owner determination
To reduce the burden on the applicants who want to enjoy DTA benefits, China tax bureaus created the “safe harbor rule”, where the applicant can be determined as a beneficial owner without going through a comprehensive analysis based on unfavorable factors upon satisfying certain conditions.
Under the current laws and regulations, the below applicants are subject to the safe harbor rule for their dividends, regardless of the assessment outcome based on the unfavorable factors:
The applicant is a company that is a tax resident of a state that has a valid DTA with China (hereinafter, the DTA counterparty) and is listed in that jurisdiction;
The applicant is the government of the DTA counterparty;
The applicant is an individual who is a resident of the DTA counterparty; and
The applicant is a subsidiary that is 100 percent directly or indirectly owned by one or more persons covered by the safe harbor rule (In the case the subsidiary is indirectly owned by the persons covered by the safe harbor rule, the multi-tier holders should be either Chinese residents or residents of the DTA counterparty).
Can an applicant still apply for a DTA if they neither pass the beneficial owner assessment nor are they eligible for the safe harbor rule?
For applicants deriving dividends from China who neither pass the beneficial owner unfavorable factor assessment nor are qualified to enjoy the safe harbor rule, there are other opportunities to qualify as beneficial owners.
Applicants deriving dividend income from China will still be deemed as a beneficial owner if the shareholder who directly or indirectly holds a 100 percent share of the applicant is a qualified beneficial owner who can enjoy the DTA benefits. Furthermore, the abovementioned shareholder should fall into either of the below circumstances:
Circumstance I: Where the above-mentioned shareholder is a resident of the same country (region) for which the applicant is a resident, there is no special requirement for the intermediate shareholders (if any); and
Circumstance II: Where the above-mentioned shareholder is not a resident of the country (region) for which the applicant is a resident, then the above-mentioned shareholder and any intermediate shareholders should be qualified to enjoy the same or better DTA treatment compared to that is entitled to the resident of the country (region) for which the applicant is a resident.
Also Read
Find a list of Free Trade and bilateral trade agreements in our guide.
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