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   138964篇
  免费   15663篇
  国内免费   7687篇
化学   99297篇
晶体学   1734篇
力学   6624篇
综合类   483篇
数学   14987篇
物理学   39189篇
  2023年   950篇
  2022年   1872篇
  2021年   2527篇
  2020年   3780篇
  2019年   5137篇
  2018年   4061篇
  2017年   3788篇
  2016年   6978篇
  2015年   6015篇
  2014年   7047篇
  2013年   9301篇
  2012年   8413篇
  2011年   8121篇
  2010年   7411篇
  2009年   7371篇
  2008年   7198篇
  2007年   6264篇
  2006年   5562篇
  2005年   5212篇
  2004年   4614篇
  2003年   4181篇
  2002年   5021篇
  2001年   4103篇
  2000年   3478篇
  1999年   2185篇
  1998年   1749篇
  1997年   1493篇
  1996年   1452篇
  1995年   1193篇
  1994年   1296篇
  1993年   1202篇
  1992年   1144篇
  1991年   1218篇
  1990年   1215篇
  1989年   1080篇
  1988年   962篇
  1987年   945篇
  1986年   918篇
  1985年   962篇
  1984年   934篇
  1983年   843篇
  1982年   811篇
  1979年   804篇
  1978年   813篇
  1977年   807篇
  1976年   919篇
  1975年   813篇
  1974年   844篇
  1973年   848篇
  1972年   752篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Knyazev  Yu. V.  Kazak  N. V.  Gavrichkov  V. A.  Polukeev  S. I.  Ovchinnikov  S. G. 《JETP Letters》2022,116(8):567-573
JETP Letters - Changes in the magnetic properties of FeBO3 single crystals in the course of spin crossover occurring with increasing pressure up to 63 GPa are studied both experimentally and...  相似文献   
12.
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs.  相似文献   
13.
14.
Russian Physics Journal - The temperature dependences of the linear dielectric permittivity ε′ and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a...  相似文献   
15.
Technical Physics - Taking damping into account in the problems of structural dynamics is an important and nontrivial problem. Its complexity is primarily determined by the required specification...  相似文献   
16.
Theoretical and Mathematical Physics - We consider three one-dimensional superconducting structures: 1) the one with $$p$$ -wave superconductivity; 2) the main experimental model of a nanowire with...  相似文献   
17.
Russian Physics Journal - A unified equation for the pressure drop in the apparatus with the stationary and fluidized granular layers is derived. The resulting recurrent equation is used to...  相似文献   
18.
Physics of the Solid State - The interference of excited and received by current antennae magnetoelastic waves counterpropagating in an yttrium iron garnet film is experimentally studied. It is...  相似文献   
19.
Siberian Mathematical Journal - We give a simple proof of one assertion used in solving Waring’s problem.  相似文献   
20.
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   
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