首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   67306篇
  免费   10030篇
  国内免费   6548篇
化学   45192篇
晶体学   639篇
力学   4540篇
综合类   515篇
数学   8410篇
物理学   24588篇
  2024年   59篇
  2023年   1356篇
  2022年   1350篇
  2021年   1980篇
  2020年   2495篇
  2019年   2384篇
  2018年   2127篇
  2017年   1880篇
  2016年   2882篇
  2015年   2949篇
  2014年   3507篇
  2013年   4702篇
  2012年   5796篇
  2011年   6014篇
  2010年   4079篇
  2009年   4018篇
  2008年   4188篇
  2007年   3790篇
  2006年   3567篇
  2005年   3092篇
  2004年   2473篇
  2003年   1868篇
  2002年   1574篇
  2001年   1457篇
  2000年   1328篇
  1999年   1481篇
  1998年   1278篇
  1997年   1117篇
  1996年   1170篇
  1995年   1060篇
  1994年   1000篇
  1993年   859篇
  1992年   757篇
  1991年   661篇
  1990年   549篇
  1989年   481篇
  1988年   363篇
  1987年   346篇
  1986年   295篇
  1985年   300篇
  1984年   201篇
  1983年   174篇
  1982年   145篇
  1981年   112篇
  1980年   82篇
  1978年   56篇
  1977年   52篇
  1976年   50篇
  1975年   57篇
  1973年   57篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Ferroptosis triggered by hemin is regarded as a primary factor accounting for neuronal death secondary to intracerebral hemorrhage. Thus, compounds with inhibitory effect on hemin-induced ferroptosis might be potential medicines to prevent neuronal death caused by intracerebral hemorrhage. Herein, we investigate whether maltol could alleviate hemin-induced SH-SY5Y cell ferroptosis and its potential mechanisms. It is found that maltol effectively prevents hemin-induced SH-SY5Y cell ferroptosis via three pathways. The first one is inhibiting intracellular iron increase via preventing upregulation of transferrin receptor, the second one is alleviating lipid peroxidation via attenuating H2O2 generation by NOX4 and promoting H2O2 clearance by catalase, and the third one is to reduce peroxidized lipids via maintaining GPX4/GSH pathway. Therefore, maltol is a novel agent preventing hemin-induced SH-SY5Y cell ferroptosis.  相似文献   
92.
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of...  相似文献   
93.
Along with the rapid development of industry, VOCs gradually move into the spotlight, and now become a kind of harmful environmental pollutants that cannot be overlooked. This paper introduces the hazards of VOCs and the common catalytic combustion catalysts, noble metal catalysts and non-noble metal catalysts, for the elimination of VOCs. Perovskite catalysts, as one of the non-noble catalysts, play an important role in the field of catalytic combustion in recent years. According to the classification of elements doping in perovskites, the research achievements in the past five years were analyzed and reviewed. In addition, this paper also analyzes and elaborates the reaction kinetics and QSAR/QSPR models for the introduction of structural properties and reaction mechanisms.  相似文献   
94.
95.
96.
Journal of Thermal Analysis and Calorimetry - In order to understand the catalytic effects of inherent inorganic elements in biomass on the pyrolysis mechanism of lignin, density functional theory...  相似文献   
97.
98.
A novel ZnCo2O4/Bi2O3 heterojunction photocatalyst was prepared via balling method. The enhanced photocatalytic activity is mainly attributed to the broad photoabsorption and low recombination rate of photogenerated electron-hole pairs, which is driven by the photogenerated potential difference formed at the ZnCo2O4/Bi2O3 heterojunction interface.  相似文献   
99.
The first-principles DFT calculations together with microkinetic analysis reveal the complex catalytic mechanism of low-content NO oxidation on CrO2(110) at room temperature. It quantitatively makes clear that CrO2(110) can exhibit considerable activity with the Mars-van-Krevelen mechanism preferred, and the nitrate species serves as the key poisoning species.  相似文献   
100.
The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two- and three-dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight-fold conductivity enhancement. The first evaluation of redox behavior of buckyball- or tetracyanoquinodimethane-integrated crystalline was conducted. In parallel with tailoring the D-A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli-controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号