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   1571440篇
  免费   32324篇
  国内免费   8255篇
化学   689578篇
晶体学   20588篇
力学   75670篇
综合类   106篇
数学   244330篇
物理学   383216篇
无线电   198531篇
  2021年   14815篇
  2020年   17429篇
  2019年   17552篇
  2018年   15567篇
  2017年   13862篇
  2016年   30748篇
  2015年   22038篇
  2014年   32916篇
  2013年   78907篇
  2012年   42514篇
  2011年   41577篇
  2010年   41603篇
  2009年   46209篇
  2008年   43796篇
  2007年   41640篇
  2006年   46032篇
  2005年   39141篇
  2004年   39777篇
  2003年   36908篇
  2002年   37527篇
  2001年   37594篇
  2000年   32759篇
  1999年   29498篇
  1998年   27722篇
  1997年   27552篇
  1996年   27005篇
  1995年   24747篇
  1994年   24237篇
  1993年   23616篇
  1992年   23630篇
  1991年   23782篇
  1990年   22579篇
  1989年   22177篇
  1988年   21364篇
  1987年   20109篇
  1986年   18923篇
  1985年   25438篇
  1984年   26524篇
  1983年   22424篇
  1982年   23778篇
  1981年   22946篇
  1980年   22219篇
  1979年   22234篇
  1978年   23404篇
  1977年   22988篇
  1976年   22597篇
  1975年   21267篇
  1974年   20879篇
  1973年   21376篇
  1972年   15540篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
111.
Taherian  A.  Toutounian  F. 《Numerical Algorithms》2021,88(4):1831-1850
Numerical Algorithms - In this paper, the block generalized product-type bi-conjugate gradient (GPBi-CG) method for solving large, sparse nonsymmetric linear systems of equations with multiple...  相似文献   
112.
Mobile Networks and Applications - Blockchain applications have continuously improved ever since its first debut on cryptocurrency. From then on, its uses have branched out from the financial...  相似文献   
113.
Fullerenes are candidates for theranostic applications because of their high photodynamic activity and intrinsic multimodal imaging contrast. However, fullerenes suffer from low solubility in aqueous media, poor biocompatibility, cell toxicity, and a tendency to aggregate. C70@lysozyme is introduced herein as a novel bioconjugate that is harmless to a cellular environment, yet is also photoactive and has excellent optical and optoacoustic contrast for tracking cellular uptake and intracellular localization. The formation, water-solubility, photoactivity, and unperturbed structure of C70@lysozyme are confirmed using UV-visible and 2D 1H, 15N NMR spectroscopy. The excellent imaging contrast of C70@lysozyme in optoacoustic and third harmonic generation microscopy is exploited to monitor its uptake in HeLa cells and lysosomal trafficking. Last, the photoactivity of C70@lysozyme and its ability to initiate cell death by means of singlet oxygen (1O2) production upon exposure to low levels of white light irradiation is demonstrated. This study introduces C70@lysozyme and other fullerene-protein conjugates as potential candidates for theranostic applications.  相似文献   
114.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
115.
Russian Physics Journal - The specific features of the sorption activity of silver nanoparticles (AgNPs) on biodegradable polymers of natural (collagen) and artificial (polyamide 6.6) origin have...  相似文献   
116.
117.
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials.  相似文献   
118.
Journal of Communications Technology and Electronics - Abstract—The matrix coefficients of projection models of strip lines obtained using the Chebyshev basis are presented as a sum of...  相似文献   
119.
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed....  相似文献   
120.
Analog Integrated Circuits and Signal Processing - This paper presents the complete design of a phase locked loop-based clock synthesizer for reconfigurable analog-to-digital converters. The...  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