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   435114篇
  免费   19545篇
  国内免费   12661篇
化学   222388篇
晶体学   6601篇
力学   23652篇
综合类   670篇
数学   62422篇
物理学   151587篇
  2022年   4906篇
  2021年   5408篇
  2020年   5978篇
  2019年   6042篇
  2018年   14599篇
  2017年   15006篇
  2016年   12769篇
  2015年   8212篇
  2014年   10281篇
  2013年   18347篇
  2012年   21124篇
  2011年   30740篇
  2010年   20341篇
  2009年   20134篇
  2008年   25574篇
  2007年   28124篇
  2006年   14506篇
  2005年   18788篇
  2004年   14069篇
  2003年   12515篇
  2002年   10330篇
  2001年   10006篇
  2000年   7981篇
  1999年   6663篇
  1998年   5540篇
  1997年   5268篇
  1996年   5201篇
  1995年   4623篇
  1994年   4428篇
  1993年   4227篇
  1992年   4240篇
  1991年   4292篇
  1990年   3902篇
  1989年   3684篇
  1988年   3607篇
  1987年   3442篇
  1986年   3255篇
  1985年   4215篇
  1984年   4338篇
  1983年   3467篇
  1982年   3636篇
  1981年   3516篇
  1980年   3383篇
  1979年   3476篇
  1978年   3569篇
  1977年   3416篇
  1976年   3547篇
  1975年   3231篇
  1974年   3217篇
  1973年   3310篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Li  Y.  Shi  W. H.  Dong  L. M.  Xu  S. X.  Huang  H. J.  Yin  J. R. 《Journal of Applied Spectroscopy》2022,89(3):534-541
Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,...  相似文献   
32.
Photoelectrochemical (PEC) cytosensors, a combination of the PEC process and the living-cell assay, have emerged as a powerful tool in the analytical and biological science. This mini review provides a brief introduction of this arena and summaries the key steps about the development of PEC cytosensors with representative examples, followed by future prospects based on our own opinions.  相似文献   
33.
Computational Optimization and Applications - We consider a continuous-time optimization method based on a dynamical system, where a massive particle starting at rest moves in the conservative...  相似文献   
34.
Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...  相似文献   
35.
Journal of Radioanalytical and Nuclear Chemistry - The simplified 8-oxide system (SiO2-B2O3-Na2O-Al2O3-CaO-TiO2-MoO3-La2O3) has been prepared under two types of cooling methods, and analyzed with...  相似文献   
36.
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   
37.
38.
39.
Li  Jun  Zheng  Dayong  Wei  Ning  Sun  Yunfeng  Liu  Li  Yuan  Yuan  Jiang  Qinghua 《Chemistry of Natural Compounds》2022,58(4):650-652
Chemistry of Natural Compounds - A new quassinoid, dehydrobruceantinol B (1), was isolated from the seeds of Brucea javanica, together with two known compounds, bruceantinol (2) and bruceine A (3)....  相似文献   
40.
Xu  Mengtao  Li  Changyou  Sun  Yang  Yang  Tianzhi  Zhang  Hongzhuang  Liu  Zhendong  Liu  Haiyang  Li  Zhenyuan  Zhang  Yimin 《Nonlinear dynamics》2021,105(4):3061-3092
Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are...  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