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   38071篇
  免费   388篇
  国内免费   148篇
化学   19089篇
晶体学   697篇
力学   1632篇
综合类   2篇
数学   3615篇
物理学   13572篇
  2022年   299篇
  2021年   352篇
  2020年   327篇
  2019年   331篇
  2018年   531篇
  2017年   449篇
  2016年   717篇
  2015年   428篇
  2014年   751篇
  2013年   1629篇
  2012年   1569篇
  2011年   1925篇
  2010年   1378篇
  2009年   1389篇
  2008年   1598篇
  2007年   1605篇
  2006年   1471篇
  2005年   1283篇
  2004年   1184篇
  2003年   1040篇
  2002年   997篇
  2001年   1397篇
  2000年   993篇
  1999年   815篇
  1998年   619篇
  1997年   598篇
  1996年   529篇
  1995年   484篇
  1994年   457篇
  1993年   409篇
  1992年   492篇
  1991年   490篇
  1990年   489篇
  1989年   441篇
  1988年   473篇
  1987年   462篇
  1986年   406篇
  1985年   469篇
  1984年   490篇
  1983年   354篇
  1982年   401篇
  1981年   386篇
  1980年   328篇
  1979年   417篇
  1978年   389篇
  1977年   409篇
  1976年   396篇
  1975年   354篇
  1974年   341篇
  1973年   346篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Let T be a bounded linear operator in a Banach space, with σ(T)={1}. In 1983, Esterle-Berkani' s conjecture was proposed for the decay of differences (I - T) T^n as follows: Eitheror lim inf (n→∞(n+1)||(I-T)T^n||≥1/e or T = I. We prove this claim and discuss some of its consequences.  相似文献   
42.
Differentiation of functions w.r.t. finite atomless measures with compact support on the real line is introduced. The related harmonic calculus is similar to that of the classical Lebesgue case. As an application we obtain the Weyl exponent for the spectral asymptotics of the Laplacians w.r.t. linear Cantor-type measures with arbitrary weights.  相似文献   
43.
The Bargaining Problem paradigm is extended to time-consuming conflict situations. Such a situation can be represented by a chain of bargaining domains, each representing the conflict at a different point in time. The solution function selects a point in the union of all these domains. We characterize a solution function which satisfies several requirements and explore its properties. One of the results is that an extension of the Adding requirement (Thomson-Myerson 1980) is enough, under some conditions, to yield a solution point, so there is no need to extend the stronger requirements of Independence of Irrelevant Alternatives (Nash 1950) or Monotonicity (Kalai-Smorodinsky 1975).  相似文献   
44.
The universal condition for the formation of omnidirectional band gaps (OBG) in photonic crystal (PC) was derived with consideration of permeability of the materials. And it was found that there are four kinds of PCs: one of them has no OBG, and one always possesses OBG. For the other two kinds of PCs, there are OBG for only TM or TE waves respectively. Moreover, in all PCs, the OBG can be broadened by decreasing the refractive index of the ambient medium or/and increasing the contrast between the wave impedances of the component materials of the PC. PACS 42.70.Qs; 71.20.Tx  相似文献   
45.
Efficient quenching of eosin phosphorescence by amino-acid derivatives of fullerene (AADFs) such as C60-alanine and C60-glycine in aqueous solutions indicates the possibility of transferring electrons from eosin to fullerene upon collisions or in the exciplex state. To investigate electron transfer in the protein structure, we studied the process of incorporation of C60-alanine and C60-glycine into the heme pocket of myoglobin by controlling Förster quenching. The dissociation constant for the protein-AADF complex was estimated.  相似文献   
46.
P. P. Shirshov Institute of Oceanology, USSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 2, pp. 180–184, May, 1989.  相似文献   
47.
48.
The process of preservation of newspaper with aqueous solutions and dispersions of acrylic copolymers is considered from the instant of impregnation till removal of the polymeric preservative from paper.  相似文献   
49.
The inclusive reduced velocity correlation functions of the intermediate mass fragments were measured in the reactions of 36Ar + 112,124Sn at 35 MeV/u. The anti-correlation is observed to be stronger in 36Ar + 124Sn system than that in 36Ar + 112Sn. The difference of the correlation functions between the two reactions is mainly contributed by the particle pairs with high momenta. A three body Coulomb repulsive trajectory model is employed to calculate the emission time scale of the IMFs for the two systems. The time scale is 150 fm/c in 36Ar + 112Sn and 120 fm/c in the 36Ar + 124Sn, respectively.  相似文献   
50.
We consider the problem of guillotine cutting a rectangular sheet into two rectangular pieces without rotations. The question is whether there exists a cutting pattern with given numbers of occurrences of both rectangular pieces. A polynomial time algorithm is described to construct the convex hull of solutions to this problem.  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