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   1351115篇
  免费   44796篇
  国内免费   17556篇
化学   679841篇
晶体学   20747篇
力学   79328篇
综合类   638篇
数学   247358篇
物理学   385555篇
  2022年   12801篇
  2021年   16707篇
  2020年   19016篇
  2019年   19519篇
  2018年   13615篇
  2016年   30964篇
  2015年   24437篇
  2014年   35271篇
  2013年   80508篇
  2012年   42261篇
  2011年   36654篇
  2010年   40025篇
  2009年   42869篇
  2008年   34083篇
  2007年   28391篇
  2006年   36363篇
  2005年   26704篇
  2004年   28302篇
  2003年   27017篇
  2002年   28409篇
  2001年   25771篇
  2000年   23615篇
  1999年   23071篇
  1998年   22156篇
  1997年   22077篇
  1996年   22517篇
  1995年   20332篇
  1994年   19728篇
  1993年   18937篇
  1992年   18387篇
  1991年   18644篇
  1990年   17730篇
  1989年   17638篇
  1988年   17061篇
  1987年   17056篇
  1986年   15959篇
  1985年   22352篇
  1984年   23663篇
  1983年   19864篇
  1982年   21594篇
  1981年   20828篇
  1980年   20127篇
  1979年   20106篇
  1978年   21518篇
  1977年   21061篇
  1976年   20728篇
  1975年   19391篇
  1974年   19021篇
  1973年   19495篇
  1972年   14021篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Journal of Radioanalytical and Nuclear Chemistry - In this paper a study for the selection of an NPE (nonylphenol ethoxylates)—free cocktail is discussed in order to be used for our routine...  相似文献   
132.
3,4-Difluorobenzyl(1-ethyl-5-(4-((4-hydroxypiperidin-1-yl)-methyl)thiazol-2-yl)-1H-indol-3-yl)carbamate (NAI59), a small molecule with outstanding therapeutic effectiveness to anti-pulmonary fibrosis, was developed as an autotaxin inhibitor candidate compound. To evaluate the pharmacokinetics and plasma protein binding of NAI59, a UPLC–MS/MS method was developed to quantify NAI59 in plasma and phosphate-buffered saline. The calibration curve linearity ranged from 9.95 to 1990.00 ng/mL in plasma. The accuracy was −6.8 to 5.9%, and the intra- and inter-day precision was within 15%. The matrix effect and recovery, as well as dilution integrity, were within the criteria. The chromatographic and mass spectrometric conditions were also feasible to determine phosphate-buffered saline samples, and it has been proved that this method exhibits good precision and accuracy in the range of 9.95–497.50 ng/mL in phosphate-buffered saline. This study is the first to determine the pharmacokinetics, absolute bioavailability, and plasma protein binding of NAI59 in rats using this established method. Therefore, the pharmacokinetic profiles of NAI59 showed a dose-dependent relationship after oral administration, and the absolute bioavailability in rats was 6.3%. In addition, the results of protein binding showed that the combining capacity of NAI59 with plasma protein attained 90% and increased with the increase in drug concentration.  相似文献   
133.
134.
Gold nanoparticles with different mean sizes were formed on antimony-doped tin oxide nanocrystals by the temperature-varied deposition-precipitation method (Au/ATO NCs). Au/ATO NCs possess strong absorption in the near-infrared region due to Drude excitation in addition to the localized surface plasmon resonance (LSPR) of AuNPs around 530 nm. Au/ATO NCs show thermally activated catalytic activity for the oxidation of cinnamyl alcohol to cinnamaldehyde by hydrogen peroxide. The catalytic activity increases with a decrease in the mean Au particle size (dAu) at 5.3 nm≤dAu≤8.2 nm. Light irradiation (λex >660 nm, ∼0.5 sun) of Au/ATO NCs increases the rate of reaction by more than twice with ∼95 % selectivity. Kinetic analyses indicated that the striking enhancement of the reaction stems from the rise in the temperature near the catalyst surface of ∼30 K due to the photothermal effect of the ATO NCs.  相似文献   
135.
136.
137.
Journal of Russian Laser Research - We analyze the way of advancing to tender X-rays the short-wavelength bound of the operating range of flat-field grating spectrographs. We design two VLS grating...  相似文献   
138.
Russian Chemical Bulletin - The N-methylation of primary carboxamides is based on two consecutive reactions. The silylation of the corresponding carboxamides with chloro(chloromethyl)dimethylsilane...  相似文献   
139.
Journal of Structural Chemistry - Structural parameters and relative Gibbs free energies are calculated by density functional theory methods for four tetrafluoro derivatives of zinc(II)...  相似文献   
140.
Crystallography Reports - Electron backscattered diffraction (EBSD) has been used to analyze structures of natural minerals and artificial compounds for almost three decades. In recent years, it is...  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