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   147967篇
  免费   1890篇
  国内免费   590篇
化学   83864篇
晶体学   2156篇
力学   5489篇
综合类   5篇
数学   16329篇
物理学   42604篇
  2016年   1732篇
  2015年   1416篇
  2014年   1783篇
  2013年   6026篇
  2012年   4451篇
  2011年   5695篇
  2010年   3418篇
  2009年   3188篇
  2008年   5064篇
  2007年   5155篇
  2006年   5192篇
  2005年   5071篇
  2004年   4442篇
  2003年   3995篇
  2002年   3802篇
  2001年   3914篇
  2000年   2969篇
  1999年   2435篇
  1998年   2146篇
  1997年   2155篇
  1996年   2123篇
  1995年   2007篇
  1994年   1811篇
  1993年   1797篇
  1992年   1989篇
  1991年   1964篇
  1990年   1869篇
  1989年   1891篇
  1988年   1903篇
  1987年   1861篇
  1986年   1775篇
  1985年   2408篇
  1984年   2580篇
  1983年   2087篇
  1982年   2550篇
  1981年   2328篇
  1980年   2363篇
  1979年   2348篇
  1978年   2499篇
  1977年   2356篇
  1976年   2380篇
  1975年   2283篇
  1974年   2129篇
  1973年   2325篇
  1972年   1403篇
  1971年   1054篇
  1970年   1005篇
  1969年   1001篇
  1968年   1126篇
  1967年   1166篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
We provide a detailed investigation of limits of N–soliton solutions of the Toda lattice as N tends to infinity. Our principal results yield new classes of Toda solutions including, in particular, new kinds of soliton–like (i.e., reflectionless) solutions. As a byproduct we solve an inverse spectral problem for one–dimensional Jacobi operators and explicitly construct tri–diagonal matrices that yield a purely absolutely continuous spectrum in (-1,1) and give rise to an eigenvalue spectrum that includes any prescribed countable and bounded subset of . Received: 16 October 1995/Accepted: 23 July 1996  相似文献   
22.
In situ measurements of gas-liquid surface reactions of single aerosol microdroplets are presented. By means of optical levitation in combination with elastic (Mie) and inelastic (Raman) light scattering it is possible to get information on the chemistry of e.g. acid/base reactions as well as the physical behavior of single microparticles.  相似文献   
23.
In this paper we construct a primitive, non-symmetric 3-class association scheme with parameters v = 36, v1 = 7, p111 = 0 and p211 = 4 and show that such a scheme is determined by its parameters.  相似文献   
24.
The phase behavior of binary blends of poly(ether ether ketone) (PEEK), sulfonated PEEK, and sulfamidated PEEK with aromatic polyimides is reported. PEEK was determined to be immiscible with a poly(amide imide) (TORLON 4000T). Blends of sulfonated and sulfamidated PEEK with this poly(amide imide), however, are reported here to be miscible in all proportions. Blends of sulfonated PEEK and a poly(ether imide) (ULTEM 1000) are also reported to be miscible. Spectroscopic investigations of the intermolecular interactions suggest that formation of electron donoracceptor complexes between the sulfonated/sulfamidated phenylene rings of the PEEKs and the n-phenylene units of the polyimides are responsible for this miscibility. © 1993 John Wiley & Sons, Inc.  相似文献   
25.
26.
The Mathematical Intelligencer encourages comments about the material in this issue. Letters to the editor should be sent to either of the editors-in-chief, Chandler Davis or Marjorie Senechal.  相似文献   
27.
We discuss some variant superfield representations which can arise by the replacement of some of the usual fields in a multiplet with p-form gauge fields.  相似文献   
28.
The purpose of this note is to describe a procedure for transferring familiar estimates for transition probabilities on RN to transition probabilities on compact manifolds.  相似文献   
29.
The electro-optic response of ferroelectric smectic C* liquid crystals has been studied. Anomalous switching behaviour of such materials which possess a negative dielectric anisotropy has been reported. These materials show a minimum in response time at a sufficiently high field. We present results showing the dependency of this minimum upon spontaneous polarisation and the effect of AC bias. Calculations based upon the equation of motion of the director around the cone are presented which describe this effect and its dependence on the relative magnitudes of the spontaneous polarization and dielectric anisotropy of the material. Good agreement with the experimental results is found.  相似文献   
30.
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