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   1665247篇
  免费   32463篇
  国内免费   8426篇
化学   745784篇
晶体学   21178篇
力学   77812篇
综合类   120篇
数学   252415篇
物理学   406052篇
无线电   202775篇
  2021年   14882篇
  2020年   17499篇
  2019年   17670篇
  2018年   18739篇
  2017年   17389篇
  2016年   32201篇
  2015年   22429篇
  2014年   33079篇
  2013年   79046篇
  2012年   47704篇
  2011年   51195篇
  2010年   45374篇
  2009年   49092篇
  2008年   52164篇
  2007年   51346篇
  2006年   51497篇
  2005年   47387篇
  2004年   45944篇
  2003年   41773篇
  2002年   41138篇
  2001年   41124篇
  2000年   35142篇
  1999年   30638篇
  1998年   28152篇
  1997年   27855篇
  1996年   27242篇
  1995年   24899篇
  1994年   24400篇
  1993年   23829篇
  1992年   24127篇
  1991年   24239篇
  1990年   23030篇
  1989年   22634篇
  1988年   21844篇
  1987年   20461篇
  1986年   19344篇
  1985年   25806篇
  1984年   26779篇
  1983年   22605篇
  1982年   23890篇
  1981年   23060篇
  1980年   22295篇
  1979年   22413篇
  1978年   23560篇
  1977年   23188篇
  1976年   22875篇
  1975年   21609篇
  1974年   21226篇
  1973年   21768篇
  1972年   15907篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
112.
Physics of Atomic Nuclei - The muon puzzle is an excess of muon bundles generated by primary cosmic rays (PCR) at energies above 10 $${}^{17}$$ eV compared to estimations that assume even a heavy...  相似文献   
113.
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   
114.
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   
115.
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   
116.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
117.
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   
118.
119.
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   
120.
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   
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