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会计师事务所转制提高了审计质量吗?——基于事务所转制前后的纵向分析 被引量:3
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作者 陈小林 张雪华 《会计论坛》 CSSCI 2016年第1期3-25,共23页
有别于过去文献,文章是在事务所全部完成转制后,采用事务所转制前后相邻2年所审计的同一批上市公司作为研究样本,从审计意见、盈余管理和会计稳健性三个角度重新考察了事务所转制带来的影响。实证结果发现,事务所转变为特殊普通合... 有别于过去文献,文章是在事务所全部完成转制后,采用事务所转制前后相邻2年所审计的同一批上市公司作为研究样本,从审计意见、盈余管理和会计稳健性三个角度重新考察了事务所转制带来的影响。实证结果发现,事务所转变为特殊普通合伙制后,发表非标准意见的概率更高,盈余管理程度降低,会计稳健性更高。监管部门推动的事务所转制,在转制后提高了审计谨慎性,审计质量得到改进。 展开更多
关键词 事务所转制 法律责任 审计质量 审计意见 盈余质量
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光致热效应促进的全光谱光催化CO_(2)还原 被引量:2
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作者 汪弘嘉 王艳杰 +3 位作者 郭令举 张雪华 Caue Ribeiro 贺涛 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2020年第1期131-139,共9页
以半导体等为催化剂,在太阳能作用下将CO2和H2O转化为可再生燃料与氧气的“人工光合作用”有望同时解决目前面临的严峻能源和环境问题,因而备受关注.但半导体催化剂光谱响应范围较窄、表面反应动力学缓慢,从而导致目前仍无法获得可观的... 以半导体等为催化剂,在太阳能作用下将CO2和H2O转化为可再生燃料与氧气的“人工光合作用”有望同时解决目前面临的严峻能源和环境问题,因而备受关注.但半导体催化剂光谱响应范围较窄、表面反应动力学缓慢,从而导致目前仍无法获得可观的太阳能-燃料转换效率.已有很多研究采用了晶面调控、元素掺杂和异质结构建等方法,以提高半导体光催化剂的太阳能-燃料转换效率,但效果仍不令人满意,主要原因是半导体光催化剂很难在吸收带边-氧化还原能力和活性-稳定性这两种关系中取得较好的平衡.此外,光催化反应中的动力学也是主要问题之一,尤其在人工光合作用反应中,CO2还原半反应和H2O氧化半反应的动力学均较困难, 这已成为共识, 而解决这个问题, 将有助于我们从一新的角度理解光催化过程, 从而提升光催化反应性能.本文以Au NP/金红石为模型催化剂, 纯金红石为参照, 证明了存在太阳光中的红外光致热和可见光诱导的等离激元热效应等两类光致热效应, 它们均可以促进人工光合作用反应. 研究发现, 人工光合作用反应与其他许多化学反应一样, 表观活化能为正, 从而表明动力学因素在该反应中起着重要作用. 此外, 根据不同反应温度下的结果, 通过计算Au NP/金红石和纯金红石上生成CO和CH4的表观活化能, 发现在这二种样品上CH4的表观活化能均高于CO, 这就从动力学上解释了热力学上更容易得到的CH4在绝大多光催化CO2还原反应中的产率均低于CO. 此外, 无论是对于CO还是CH4, Au NP/金红石的催化表观活化能均低于纯金红石的. 因此, 本文从实验上提供了贵金属纳米粒子改善人工光合作用动力学的实验证据,并从动力学角度解释了人工光合作用反应中的活性和选择性问题. 本研究证明了动力学因素在光催化反应, 尤其是人工光合作用反应中的重要性, 并提出了从动力学角度提升人工光合作用反应的新方法, 即利用太阳光的光致热效应加速反应, 这不仅有助于提升太阳能转化效率, 也有望减少反应设备成本, 从而促进其大规模应用. 展开更多
关键词 CO_(2)还原 表观反应活化能 反应动力学 光致热效应 光-热协同效应
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均相催化CO_(2)/H_(2)还原羰基化合成高值化学品研究进展 被引量:5
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作者 张雪华 曹彦伟 +2 位作者 陈琼遥 沈超仁 何林 《物理化学学报》 SCIE CAS CSCD 北大核心 2021年第5期81-94,共14页
高效利用温室气体CO_(2)资源作为催化合成的C1原料既能有效减少它向大气的排放,又同时创造经济价值。其中基于CO_(2)还原性转化的化学品合成新路线是拓展其资源化利用的热点。如能以清洁、高原子经济性的H_(2)作为还原剂实现惰性CO_(2)... 高效利用温室气体CO_(2)资源作为催化合成的C1原料既能有效减少它向大气的排放,又同时创造经济价值。其中基于CO_(2)还原性转化的化学品合成新路线是拓展其资源化利用的热点。如能以清洁、高原子经济性的H_(2)作为还原剂实现惰性CO_(2)还原性转化,通过羰基化构筑C―O、C―N和C―C键,合成醛/醇、羧酸、酯、酰胺等化学品,将极大扩展由CO_(2)高值化利用的范围与种类。近年来,均相催化CO_(2)/H_(2)还原羰基化制备化学品取得长足的进展,但该反应目前仍存在常用贵金属催化剂反应条件苛刻、目标产物选择性低以及底物适用性差等问题,制约了其的发展和应用。因此,设计开发更加高效的催化体系使反应能在相对温和的条件下得以实现仍然是一较大挑战。本文综述近年来均相催化CO_(2)、H_(2)参与的烯烃羰基化、胺羰基化、醇/醚羰基化以及其它羰基化反应研究及发展现状,重点探讨了不同种类的金属催化剂对反应过程的影响。最后对未来可能的发展方向进行了探讨和展望。 展开更多
关键词 二氧化碳 氢气 还原 均相催化 羰基化
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Construction of Comprehensive Development Index and Analysis on the Development Trend of Solar Energy Industry 被引量:1
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作者 Linlin Jia xuehua zhang Yahui Wu 《Engineering(科研)》 2018年第8期477-485,共9页
As a strategic emerging industry, solar energy industry has been wished to ease the energy crisis and stimulate economic growth. In order to judge the development of the industry objectively, this paper constructs the... As a strategic emerging industry, solar energy industry has been wished to ease the energy crisis and stimulate economic growth. In order to judge the development of the industry objectively, this paper constructs the index system of China’s solar energy industrial development from three dimensions of micro enterprise, medium industry and macroeconomic. This paper simultaneously takes 27 specific indicators, 54 listed companies and 10206 data from 2010 to 2016 as an example to calculate the industrial development index. The result reveals that with the implementation of the support policies playing a positive role in the development of China’s solar energy industry, the solar industry has steadily improved. Solar energy industry in our country is under the support of national support policies and its technological innovation capability is relatively active. However, the moderate investment and financing activities and inadequate enterprise operational capacity, to some extent, alleviate the development of the solar energy industry. The above shows that the solar energy industrial development index and its evaluation methods can help people to accurately grasp the development trend of the solar energy industry and accurately identify the development of advantages and disadvantages. 展开更多
关键词 SOLAR Energy Industry Development INDEX COMPREHENSIVE INDEX Method ANALYTIC HIERARCHY Process
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三大产业对通货膨胀的非对称性作用及实证分析
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作者 李清明 谭燕珍 +2 位作者 陈虹静 张雪花 贺军州 《世界经济探索》 2018年第1期1-8,共8页
本文将理论模型与调查数据相结合,探讨了不同发展阶段经济体中不同产业对各自经济体通货膨胀的影响。首先建立多生产部门货币政策模型并结合统计数据估计模型参数,然后对随后年份的通货膨胀率进行预测,同时将之与单一生产部门货币政策... 本文将理论模型与调查数据相结合,探讨了不同发展阶段经济体中不同产业对各自经济体通货膨胀的影响。首先建立多生产部门货币政策模型并结合统计数据估计模型参数,然后对随后年份的通货膨胀率进行预测,同时将之与单一生产部门货币政策模型预测的通货膨胀率进行比较。分析显示相较于单生产部门货币政策模而言多生产部门货币政策模型预测值总体更为准确有效。同时根据多生产部门货币政策模型研究发现,第一产业占比较高的经济体其第一产业对其通货膨胀的贡献为负,二、三产业贡献总体为正;第一产业占比较低且第二、三产业占比较高的经济体其第三产业对其通货膨胀的贡献为负,一、二产业的贡献总体为正;而对几乎所有的经济体来说第二产业对通货膨胀的贡献都为正。即不同发展阶段经济体的不同产业对通货膨胀的敏感性具有非对称性的作用,这一结论为不同经济体的政府制定较为合理的货币和产业政策提供了一定理论启示,也为不同发展阶段经济体更有效控制通货膨胀提供了方向和着力点。 展开更多
关键词 通货膨胀 货币政策模型 多生产部门 非对称性作用
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Analysis of the Problems and Countermeasures of China’s Green Credit
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作者 Xiaojie Wu xuehua zhang 《Journal of Geoscience and Environment Protection》 2018年第6期111-119,共9页
At present, China’s green credit market is the most important channel for green financing and has a great influence on the development of China’s green finance. Based on the collection and arrangement of the related... At present, China’s green credit market is the most important channel for green financing and has a great influence on the development of China’s green finance. Based on the collection and arrangement of the related data and information, the paper points out the main problems which is existing in China’s green credit by figures and examples from aspects of detail standards of policies, the matching level between deposits and loans and the management ability of avoiding environmental risk. Furthermore, the paper puts forward corresponding countermeasures of the problems. 展开更多
关键词 Green CREDIT ENVIRONMENTAL FINANCIAL POLICIES ENVIRONMENTAL Risk Management Commercial BANKS
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Effect of Several Common Processing Methods on Content Changes of Resistant Starch and Main Nutrients in ‘Luotian Chestnut’
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作者 Linling LI Bingjie HUANG +3 位作者 Hua CHENG xuehua zhang Xiaoling CHEN Shuiyuan CHENG 《Agricultural Biotechnology》 CAS 2018年第5期92-96,共5页
Using 'Luotian chestnut' as the raw material, the content changes of resistant starch and main nutrients in the processed fruit were studied after taken common processing of high-temperature steaming of canned food,... Using 'Luotian chestnut' as the raw material, the content changes of resistant starch and main nutrients in the processed fruit were studied after taken common processing of high-temperature steaming of canned food, sand-mixed frying and cooking without shells, with the aim to find out the effects of different processing methods on the content changes of nutrients in chestnuts. The result showed that there were significant differences in the resistant starch contents by different processing methods. After processing, the retention degree of resistant starch was the lowest using the methods of sand-mixed frying, of 42.42%, while the highest was found in canned chestnut products, of 93.16%. Among the main nutrients, adding water and sugar would reduce content of resistant starch, while increasing the protein content would promote the retention of resistant starch retention. The changes in lipid content had no effect or not a single promoting or weakening effects on the content of resistant starch. 展开更多
关键词 CHESTNUT Resistant starch NUTRIENTS
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Design and Reflection on Genre Analysis in Junior Middle School English Reading Teaching
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作者 xuehua zhang 《Journal of Contemporary Educational Research》 2021年第12期162-165,共4页
In order to better promote students’English learning ability and interest,this paper expounds the general process of junior middle school English reading teaching by using genre analysis,for the reference of relevant... In order to better promote students’English learning ability and interest,this paper expounds the general process of junior middle school English reading teaching by using genre analysis,for the reference of relevant personnel. 展开更多
关键词 Junior middle school English English reading teaching Genre analysis
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Erratum to: Advancing pressure sensors performance through a flexible MXene embedded interlocking structure in a microlens array
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作者 Tong Li Zhenzong Xu +6 位作者 Ben Bin Xu Zhanhu Guo Yunhong Jiang xuehua zhang Maryam Bayati Terence Xiaoteng Liu Yan-Hua Liu 《Nano Research》 SCIE EI CSCD 2024年第4期3428-3428,共1页
Erratum to Nano Research 2023,16(7):10493–10499 https://doi.org/10.1007/s12274-023-5727-6 The article“Advancing pressure sensors performance through a flexible MXene embedded interlocking structure in a microlens ar... Erratum to Nano Research 2023,16(7):10493–10499 https://doi.org/10.1007/s12274-023-5727-6 The article“Advancing pressure sensors performance through a flexible MXene embedded interlocking structure in a microlens array”,written by Tong Li,Zhenzong Xu,Ben Bin Xu,Zhanhu Guo,Yunhong Jiang,Xuehua Zhang,Maryam Bayati,Terence Xiaoteng Liu,and Yan-Hua Liu,was originally published electronically on the publisher’s internet portal on May 20,2023 without open access due to an unfortunate oversight during the conversion process.The publisher apologizes this mistake.The article is forthwith distributed under a Creative Commons Attribution 4.0 International License,which permits use,sharing,adaptation,distribution and reproduction in any medium or format,as long as you give appropriate credit to the original author(s)and the source,provide a link to the Creative Commons licence,and indicate if changes were made. 展开更多
关键词 CREATIVE PERFORMANCE STRUCTURE
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Advancing pressure sensors performance through a flexible MXene embedded interlocking structure in a microlens array
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作者 Tong Li Zhenzong Xu +6 位作者 Ben Bin Xu Zhanhu Guo Yunhong Jiang xuehua zhang Maryam Bayati Terence Xiaoteng Liu Yan-Hua Liu 《Nano Research》 SCIE EI CSCD 2023年第7期10493-10499,共7页
Piezoresistive composite elastomers have shown great potentials for wearable and flexible electronic applications due to their high sensitivity,excellent frequency response,and easy signal detection.A composition memb... Piezoresistive composite elastomers have shown great potentials for wearable and flexible electronic applications due to their high sensitivity,excellent frequency response,and easy signal detection.A composition membrane sensor with an interlocked structure has been developed and demonstrated outstanding pressure sensitivity,fast response time,and low temperature drift features.Compared with a flexible MXene-based flat sensor(Ti_(3)C_(2)),the interlocked sensor exhibits a significantly improved pressure sensitivity of two magnitudes higher(21.04 kPa^(-1)),a fast reaction speed of 31 ms,and an excellent cycle life of 5000 test runs.The viability of sensor in responding to various external stimuli with high deformation capacity has been confirmed by calculating the force distribution of a polydimethylsiloxane(PDMS)film model with a microlens structure using the solid mechanics module in COMSOL.Unlike conventional process,we utilized three-dimensional(3D)laser-direct writing lithography equipment to directly transform high-precision 3D data into a micro-nano structure morphology through variable exposure doses,which reduces the hot melting step.Moreover,the flexible pressure device is capable of detecting and distinguishing signals ranging from finger movements to human pulses,even for speech recognition.This simple,convenient,and large-format lithographic method offers new opportunities for developing novel human-computer interaction devices. 展开更多
关键词 three-dimensional(3D)lithography microlens array flexible electronics pizoresistive pressure sensors MXene
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Hydrophilic solvent recovery from switched‐on microdroplet dissolution
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作者 Romain Billet Binglin Zeng +4 位作者 Hongyan Wu James Lockhart Mike Gattrell Hongying Zhao xuehua zhang 《Droplet》 2023年第4期91-102,共12页
Switchable hydrophilicity solvents(SHSs)are a unique class of chemical compounds that can be switched between their hydrophobic and hydrophilic forms.The switchable characteristics allow SHSs to be used as emerging,gr... Switchable hydrophilicity solvents(SHSs)are a unique class of chemical compounds that can be switched between their hydrophobic and hydrophilic forms.The switchable characteristics allow SHSs to be used as emerging,green solvents for sustainable extraction and separation technology.In the production of polymeric microparticles from recycled plastics,SHSs are used to dissolve the polymer and then are switched to the hydrophilic form for separation from the generated polymeric microparticles.However,it is extremely difficult to fully recover the SHS residue from the mixtures.In this work,we will identify the key parameters that determine the level of the solvent residue during the switched‐on dissolution of emulsion microdroplets.The SHS N,N‐dimethylcyclohexylamine from solvent–polymer binary emulsion droplets was switched to the hydrophilic,water‐soluble form,triggered by addition of an acid in the surrounding aqueous phase.By applying a sensitive detection method developed in this work,we compared the levels of SHS residue in polymer microparticles obtained under 30 different dynamical and chemical conditions for the switching processes.The quantitative analysis revealed that residue levels remained constant at varied addition rates and concentration of the trigger solution,but decreased with the increase in organic phase fractions or the decrease in the emulsion temperature.Trapped water in the drops during switched‐on dissolution may have contributed to the high level of solvent residue.The understanding of the new possible mechanism for residual solvent reported in this work may help develop effective approaches for the recovery of switchable solvents in environmentally friendly separation processes. 展开更多
关键词 SWITCHED RESIDUE SEPARATION
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Simple colorimetric detection of dopamine using modified silver nanoparticles 被引量:1
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作者 Sivakumar Palanisamy xuehua zhang Tao He 《Science China Chemistry》 SCIE EI CAS CSCD 2016年第4期387-393,共7页
Dopamine(DA) plays an important role in health and peripheral nervous systems. Colorimetric detection of DA has the advantage of color change and simplicity in operation and instrumentation. Herein, we report a highly... Dopamine(DA) plays an important role in health and peripheral nervous systems. Colorimetric detection of DA has the advantage of color change and simplicity in operation and instrumentation. Herein, we report a highly sensitive and selective colorimetric detection of DA by using two specific ligands modified Ag nanoparticles, where the DA molecules can make dual recognition with high specificity. The colloidal suspension of modified Ag nanoparticles was agglomerated after interacting with DA, while the color of Ag nanoparticles suspension changed from yellow to brown, arising from the interparticle plasmon coupling during the aggregation of Ag nanoparticles. The modified Ag nanoparticles suspension and agglomeration were confirmed by transmission electron microscope images. The optical properties behind the color change were thoroughly investigated by using UV-Vis and Raman techniques. The changes in p H, zeta potential, particle size and surface charge density by adding DA were also determined by using dynamic light scattering measurements. The detection limits of modified Ag probes for DA was calculated to be 6.13′10^(-6) mol L^(-1)(S/N=2.04) and the correlation co-efficient was determined to be 0.9878. Because of the simplicity in operation and instrumentation of the colorimetric method, this work may afford a feasible, fast approach for detecting and monitoring the DA levels in physiological and pathological systems. 展开更多
关键词 银纳米颗粒 检测限 比色法 多巴胺 纳米颗粒悬浮液 外周神经系统 AG纳米粒子 透射电子显微镜
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