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   152663篇
  免费   32528篇
  国内免费   9341篇
化学   121699篇
晶体学   1127篇
力学   8954篇
综合类   469篇
数学   21348篇
物理学   40935篇
  2024年   331篇
  2023年   5558篇
  2022年   3320篇
  2021年   5371篇
  2020年   7965篇
  2019年   5607篇
  2018年   6174篇
  2017年   4582篇
  2016年   10118篇
  2015年   9879篇
  2014年   10054篇
  2013年   11768篇
  2012年   13811篇
  2011年   11004篇
  2010年   10489篇
  2009年   10010篇
  2008年   7037篇
  2007年   6186篇
  2006年   5038篇
  2005年   8014篇
  2004年   6669篇
  2003年   4491篇
  2002年   2550篇
  2001年   2041篇
  2000年   1678篇
  1999年   1908篇
  1998年   1554篇
  1997年   1554篇
  1996年   1530篇
  1995年   1347篇
  1994年   1160篇
  1993年   1092篇
  1992年   1019篇
  1991年   878篇
  1990年   744篇
  1989年   605篇
  1988年   591篇
  1987年   452篇
  1986年   398篇
  1985年   371篇
  1977年   394篇
  1976年   504篇
  1975年   539篇
  1974年   560篇
  1973年   399篇
  1972年   507篇
  1971年   445篇
  1970年   663篇
  1969年   497篇
  1968年   526篇
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
31.
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   
32.
CRANAD-2 is a fluorogenic curcumin derivative used for near-infrared detection and imaging in vivo of amyloid aggregates, which are involved in neurodegenerative diseases. We explore the performance of CRANAD-2 in two super-resolution imaging techniques, namely stimulated emission depletion (STED) and single-molecule localization microscopy (SMLM), with markedly different fluorophore requirements. By conveniently adapting the concentration of CRANAD-2, which transiently binds to amyloid fibrils, we show that it performs well in both techniques, achieving a resolution in the range of 45–55 nm. Correlation of SMLM with atomic force microscopy (AFM) validates the resolution of fine features in the reconstructed super-resolved image. The good performance and versatility of CRANAD-2 provides a powerful tool for near-infrared nanoscopic imaging of amyloids in vitro and in vivo.  相似文献   
33.
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   
34.
35.
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   
36.
Cheung  Yun Kuen  Cole  Richard  Tao  Yixin 《Mathematical Programming》2021,190(1-2):615-677
Mathematical Programming - We seek tight bounds on the viable parallelism in asynchronous implementations of coordinate descent that achieves linear speedup. We focus on asynchronous coordinate...  相似文献   
37.
Annals of the Institute of Statistical Mathematics - In this paper, a model averaging approach is developed for the linear regression models with response missing at random. It is shown that the...  相似文献   
38.
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   
39.
40.
Du  Zhong  Xu  Tao  Ren  Shuai 《Nonlinear dynamics》2021,104(1):683-689
Nonlinear Dynamics - In this paper, we investigate the interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ Lax pair. Firstly, we give the first-order breather...  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