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   5896篇
  免费   216篇
  国内免费   15篇
化学   3492篇
晶体学   43篇
力学   153篇
数学   832篇
物理学   1607篇
  2023年   35篇
  2022年   59篇
  2021年   96篇
  2020年   106篇
  2019年   121篇
  2018年   110篇
  2017年   76篇
  2016年   163篇
  2015年   134篇
  2014年   156篇
  2013年   309篇
  2012年   337篇
  2011年   401篇
  2010年   226篇
  2009年   199篇
  2008年   287篇
  2007年   286篇
  2006年   319篇
  2005年   277篇
  2004年   186篇
  2003年   177篇
  2002年   155篇
  2001年   119篇
  2000年   119篇
  1999年   92篇
  1998年   81篇
  1997年   73篇
  1996年   84篇
  1995年   78篇
  1994年   74篇
  1993年   82篇
  1992年   83篇
  1991年   67篇
  1990年   70篇
  1989年   54篇
  1988年   53篇
  1987年   43篇
  1986年   34篇
  1985年   51篇
  1984年   47篇
  1983年   53篇
  1982年   42篇
  1981年   39篇
  1980年   43篇
  1979年   39篇
  1978年   40篇
  1977年   34篇
  1976年   42篇
  1974年   40篇
  1973年   41篇
排序方式: 共有6127条查询结果,搜索用时 31 毫秒
31.
32.
This paper presents an algorithm and the supporting theory for solving a class of nonlinear multiple criteria optimization problems using Zionts—Wallenius type of interaction. The Zionts—Wallenius method, as extended in this paper, can be used for solving multiple criteria problems with concave objective and (implicit) value functions and convex feasible regions. Modifications of the method to handle nonconvex feasible regions and general nonlinear objective functions are also discussed.This research was supported, in part, by a Faculty Research Development Award and by a Council of 100 Research Grant from Arizona State University (Roy), and by a grant from Y. Jahnsson Foundation, Finland (Wallenius). The research was performed while the second author was a Visiting Professor at Arizona State University.  相似文献   
33.
V Kumar  B N Roy  D K Rai 《Pramana》1992,38(1):77-90
We have calculated total and differential cross-sections for 1sns (n = 2, 3, 4) electron impact excitation of hydrogen and hydrogenic ions at various energies in Coulomb-projected Born approximation. Distortion due to static interactions, target polarization and exchange effects has been incorporated in the initial channel. The present calculations have been compared with other theoretical and experimental results.  相似文献   
34.
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed.  相似文献   
35.
Parallel discrete event simulation (PDES) is concerned with the distributed execution of large-scale system models on multiple processors. It is an enabler in the implementation of the virtual enterprise concept, integrating semi-autonomous models of production cells, factories, or units of a supply chain. The key issue in PDES is to maintain causality relationships between system events, while maximizing parallelism in their execution. Events can be executed conservatively only when it is safe to do so, sacrificing the extent to which potential parallelism of the system can be exploited. Alternatively, they can be processed optimistically without guarantee of correctness, but incurring the overhead of a rollback to an earlier saved state when causality error is detected. The paper proposes a modified optimistic scheme for distributed simulation of constituent models of a supply chain in manufacturing, which exploits the inherent operating characteristics of its domain.  相似文献   
36.
The values of the second dissociation constant, K 2, and related thermodynamic quantities of the ampholyte bis[(2-hydroxyethyl)amino]acetic acid (BICINE) have been determined at temperatures from 5 to 55 C. The pH values of six equimolal buffer solutions, and four buffer solutions having ionic strengths (I = 0.16 mol⋅kg−1) similar to those in blood plasma, have been evaluated at 12 temperatures from 5 to 55 C using the Bates–Guggenheim convention. The liquid junction potentials (E j ) between the buffer solutions of BICINE and saturated KCl solution of the calomel electrode at 25 and 37 C have been estimated by measurement with a flowing junction cell. These values of E j have been used to ascertain the operational pH values at 25 and 37 C. The pK 2 values at 25 and 37 C are 8.333 and 8.156, respectively. The thermodynamic quantities associated with the second acid dissociation have been calculated from the values of pK 2 as a function of temperature. The zwitterionic buffer BICINE was shown to be useful as a pH standard in the region close to that of blood serum.  相似文献   
37.
Investigations of the electronic and magnetic properties of oxygen adsorbed on magnetized iron films have been carried out by means of angle and spin resolving photoelectron spectroscopy. Iron, epitaxially grown on W(100) and W(110) crystals, served as the ferromagnetic substrate. Exchange splittings of the O 2px derived level have been detected, demonstrating a magnetic coupling between the chemisorbate and the iron layer. Variations of the exchange splitting have occurred as a function of the oxygen coverage, photon energy, and emission angle. High oxygen exposures have lead to a FeO overlayer at the surface.  相似文献   
38.
39.
D. P. Roy 《Pramana》1998,51(1-2):7-26
I start with a brief introduction to Higgs mechanism and supersymmetry. Then I discuss the theoretical expectations, current limits and search strategies for Higgs boson(s) at LHC — first in the SM and then in the MSSM. Finally I discuss the signatures and search strategies for the superparticles.  相似文献   
40.
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