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   1561176篇
  免费   42960篇
  国内免费   17453篇
化学   675475篇
晶体学   21211篇
力学   77529篇
综合类   684篇
数学   245601篇
物理学   382336篇
无线电   218753篇
  2021年   17083篇
  2020年   19526篇
  2019年   19909篇
  2018年   15989篇
  2017年   14379篇
  2016年   32313篇
  2015年   24865篇
  2014年   36397篇
  2013年   83065篇
  2012年   43911篇
  2011年   40232篇
  2010年   44020篇
  2009年   49371篇
  2008年   43047篇
  2007年   39410篇
  2006年   45116篇
  2005年   37438篇
  2004年   37948篇
  2003年   35784篇
  2002年   36670篇
  2001年   34241篇
  2000年   31271篇
  1999年   29506篇
  1998年   28279篇
  1997年   28037篇
  1996年   27709篇
  1995年   25454篇
  1994年   24775篇
  1993年   23939篇
  1992年   23314篇
  1991年   23463篇
  1990年   22166篇
  1989年   21760篇
  1988年   20900篇
  1987年   19639篇
  1986年   18440篇
  1985年   24993篇
  1984年   26186篇
  1983年   22160篇
  1982年   23613篇
  1981年   22810篇
  1980年   22030篇
  1979年   21773篇
  1978年   23123篇
  1977年   22663篇
  1976年   22203篇
  1975年   20865篇
  1974年   20462篇
  1973年   21000篇
  1972年   15200篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging.  相似文献   
52.
Journal of Structural Chemistry - Atomic and electronic structures of cyclic organosilicon compound 9,9,10,10-tetraethynyl-9,10-dihydrodisilaanthracene are studied by the density functional theory....  相似文献   
53.
Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials.  相似文献   
54.
Russian Journal of Applied Chemistry - A method for the disposal of hydrolysis lignin waste based on its modification with ZnCl2 and FeCl3 and subsequent carbonization at 800°C was proposed....  相似文献   
55.
Journal of Applied Spectroscopy - Three simple, sensitive, precise, and rapid spectrophotometric methods are developed and optimized for the assay of vardenafil in pharmaceutical formulations. The...  相似文献   
56.
Russian Journal of Applied Chemistry - In September 1975, the head of Russian electrochemists, Academician A.N. Frumkin (1895–1976), in his report at the XI Mendeleev Congress on General and...  相似文献   
57.
Theoretical and Mathematical Physics - We study a phenomenological model in which dark matter in the cosmological constant form is identified with the mean energy–momentum tensor of a...  相似文献   
58.
Russian Journal of General Chemistry - Tungstophosphatozincates with the Keggin anion structure Kt5[PW11O39Zn(H2O)]?nH2O, Kt = Rb+, Cs+, (CH3)4N+; (C2H5)4N+ were synthesized. Their...  相似文献   
59.
Russian Journal of General Chemistry - The review article traces the main trends of the synthetic approach to the solution of the problem of overcoming the resistance of pathogenic bacterial...  相似文献   
60.
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