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   476069篇
  免费   12874篇
  国内免费   7576篇
化学   230378篇
晶体学   6408篇
力学   27550篇
综合类   523篇
数学   85714篇
物理学   145946篇
  2022年   3483篇
  2021年   4020篇
  2020年   4551篇
  2019年   4690篇
  2018年   20527篇
  2017年   20838篇
  2016年   15366篇
  2015年   7060篇
  2014年   8246篇
  2013年   15793篇
  2012年   20115篇
  2011年   33718篇
  2010年   21273篇
  2009年   21406篇
  2008年   27163篇
  2007年   31543篇
  2006年   12606篇
  2005年   17695篇
  2004年   13874篇
  2003年   13114篇
  2002年   10289篇
  2001年   9046篇
  2000年   7538篇
  1999年   6023篇
  1998年   5361篇
  1997年   5116篇
  1996年   5067篇
  1995年   4560篇
  1994年   4618篇
  1993年   4190篇
  1992年   4510篇
  1991年   4428篇
  1990年   4250篇
  1989年   4046篇
  1988年   4056篇
  1987年   3923篇
  1986年   3691篇
  1985年   4769篇
  1984年   4950篇
  1983年   4156篇
  1982年   4258篇
  1981年   4151篇
  1980年   4101篇
  1979年   4048篇
  1978年   4370篇
  1977年   4201篇
  1976年   4281篇
  1975年   3955篇
  1974年   3991篇
  1973年   4193篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Chen  Letian 《Geometriae Dedicata》2021,215(1):133-145
Geometriae Dedicata - We show that an n-dimensional surface whose entropy is close to that of an n-dimensional plane is close in Hausdorff distance to some n-dimensional plane at every scale....  相似文献   
33.
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   
34.
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   
35.
Chen  C. Y.  Kao  C. L.  Huang  S. T.  Kuo  C. E.  Song  P. L.  Li  W. J.  Hsu  L. T.  Li  H. T. 《Chemistry of Natural Compounds》2022,58(1):107-109
Chemistry of Natural Compounds -  相似文献   
36.
Ferrarini  A.  Finotello  A.  Salsano  G.  Auricchio  F.  Palombo  D.  Spinella  G.  Pane  B.  Conti  M. 《Acta Mechanica Sinica》2021,37(7):1192-1192
Acta Mechanica Sinica - A Correction to this paper has been published: https://doi.org/10.1007/s10409-021-01066-2  相似文献   
37.
Solar-driven interfacial vaporization by localizing solar-thermal energy conversion to the air−water interface has attracted tremendous attention. In the process of converting solar energy into heat energy, photothermal materials play an essential role. Herein, a flexible solar-thermal material di-cyan substituted 5,12-dibutylquinacridone (DCN−4CQA)@Paper was developed by coating photothermal quinacridone derivatives on the cellulose paper. The DCN−4CQA@Paper combines desired chemical and physical properties, broadband light-absorbing, and shape-conforming abilities that render efficient photothermic vaporization. Notably, synergetic coupling of solar-steam and solar-electricity technologies by integrating DCN−4CQA@Paper and the thermoelectric devices is realized without trade-offs, highlighting the practical consideration toward more impactful solar heat exploitation. Such solar distillation and low-grade heat-to-electricity generation functions can provide potential opportunities for fresh water and electricity supply in off-grid or remote areas.  相似文献   
38.
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   
39.
Journal of Analytical Chemistry - Silver nanoparticles modified with Eu3+ ions increase the intensity of the fluorescence signal by a factor of 125 in an analytical system containing doxycycline as...  相似文献   
40.
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   
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