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   185131篇
  免费   2462篇
  国内免费   645篇
化学   97345篇
晶体学   3082篇
力学   7467篇
综合类   4篇
数学   22386篇
物理学   57954篇
  2021年   1529篇
  2020年   1790篇
  2019年   2019篇
  2018年   2338篇
  2017年   2335篇
  2016年   3746篇
  2015年   2407篇
  2014年   3630篇
  2013年   8510篇
  2012年   6752篇
  2011年   8068篇
  2010年   5663篇
  2009年   5529篇
  2008年   7367篇
  2007年   7205篇
  2006年   6844篇
  2005年   6202篇
  2004年   5645篇
  2003年   5020篇
  2002年   4850篇
  2001年   5433篇
  2000年   4020篇
  1999年   3130篇
  1998年   2622篇
  1997年   2534篇
  1996年   2398篇
  1995年   2251篇
  1994年   2201篇
  1993年   2100篇
  1992年   2383篇
  1991年   2317篇
  1990年   2254篇
  1989年   2161篇
  1988年   2161篇
  1987年   2170篇
  1986年   2062篇
  1985年   2697篇
  1984年   2738篇
  1983年   2412篇
  1982年   2543篇
  1981年   2352篇
  1980年   2319篇
  1979年   2459篇
  1978年   2502篇
  1977年   2424篇
  1976年   2477篇
  1975年   2386篇
  1974年   2361篇
  1973年   2525篇
  1972年   1632篇
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
991.
The problems of determining and investigating the informative parameters of atmospheric electricity are discussed. It is shown that short-period variations in atmospheric electricity are ecologically significant. An automated system for monitoring atmospheric electricity and a method of processing the results of measurements are described. V. D. Kuznetsov Siberian Physicotechnical Institute, Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 88–98, May, 1998.  相似文献   
992.
993.
L. Ya. Karpov Physical Chemical Research Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 3, pp. 141–144, May–June, 1991.  相似文献   
994.
We find a new class of Fuchsian equations, with algebro-geometric solutions associated to a hyperelliptic curve. A method for calculating its arithmetic genus and branching points is suggested. Numerous examples are given.  相似文献   
995.
A refined technique is presented to project rotational bands observed in the well studiedZ≧60 rare-earth region into the region of stable ground-state deformation atA ~-100 with corresponding neutron numbers ofN ≧60. With this procedure, estimates of properties of so far unknown nuclei in the A~-100 region can be obtained. As an illustration, isotopes aroundN=64 are discussed within this projection method and within the frame-work of the recent quartet model.  相似文献   
996.
Some evidence is presented for a narrow peak at 1969±2 MeV (FWHM=9±2 MeV) in the missing mass spectrum of the3He(p, d) reaction, with 3 standard deviations. The nature of this state, the mass of which is below the NN threshold, is discussed in connection with structures found in other experiments.  相似文献   
997.
We study percolation in the following random environment: let Z be a Poisson process of constant intensity on ℝ2, and form the Voronoi tessellation of ℝ2 with respect to Z. Colour each Voronoi cell black with probability p, independently of the other cells. We show that the critical probability is 1/2. More precisely, if p>1/2 then the union of the black cells contains an infinite component with probability 1, while if p<1/2 then the distribution of the size of the component of black cells containing a given point decays exponentially. These results are analogous to Kesten's results for bond percolation in ℤ2. The result corresponding to Harris' Theorem for bond percolation in ℤ2 is known: Zvavitch noted that one of the many proofs of this result can easily be adapted to the random Voronoi setting. For Kesten's results, none of the existing proofs seems to adapt. The methods used here also give a new and very simple proof of Kesten's Theorem for ℤ2; we hope they will be applicable in other contexts as well. Research supported in part by NSF grant ITR 0225610 and DARPA grant F33615-01-C-1900 Research partially undertaken during a visit to the Forschungsinstitut für Mathematik, ETH Zürich, Switzerland  相似文献   
998.
999.
Final state interaction effects inpp→ pΛK + andpd3Heη reactions are explored near threshold to study the sensitivity of the cross-sections to thepΛ potential and theηN scattering matrix. The final state scattering wave functions between Λ andp andη and3He are described rigorously. The Λ production is described by the exchange of one pion and aK-meson between two protons in the incident channel. Theη production is described by a two-step model, where in the first step a pion is produced. This pion then produces anη by interacting with another nucleon  相似文献   
1000.
The 2000–2006 achievements in the field of synthesis, property examination, and application of proton-exchange membranes are reviewed on the basis of more than 120 papers.  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