全文获取类型
收费全文 | 1404961篇 |
免费 | 29732篇 |
国内免费 | 7811篇 |
专业分类
化学 | 712529篇 |
晶体学 | 20599篇 |
力学 | 76114篇 |
综合类 | 107篇 |
数学 | 246011篇 |
物理学 | 387144篇 |
出版年
2021年 | 13588篇 |
2020年 | 15997篇 |
2019年 | 16127篇 |
2018年 | 14540篇 |
2017年 | 12825篇 |
2016年 | 28839篇 |
2015年 | 21019篇 |
2014年 | 30566篇 |
2013年 | 74637篇 |
2012年 | 41553篇 |
2011年 | 41554篇 |
2010年 | 39265篇 |
2009年 | 41005篇 |
2008年 | 39652篇 |
2007年 | 36095篇 |
2006年 | 40075篇 |
2005年 | 33449篇 |
2004年 | 33717篇 |
2003年 | 31045篇 |
2002年 | 31646篇 |
2001年 | 31947篇 |
2000年 | 26977篇 |
1999年 | 23510篇 |
1998年 | 21412篇 |
1997年 | 21269篇 |
1996年 | 21302篇 |
1995年 | 19329篇 |
1994年 | 18806篇 |
1993年 | 18411篇 |
1992年 | 18813篇 |
1991年 | 18998篇 |
1990年 | 18218篇 |
1989年 | 18212篇 |
1988年 | 17817篇 |
1987年 | 17732篇 |
1986年 | 16683篇 |
1985年 | 23027篇 |
1984年 | 24083篇 |
1983年 | 20180篇 |
1982年 | 21784篇 |
1981年 | 21003篇 |
1980年 | 20342篇 |
1979年 | 20720篇 |
1978年 | 21885篇 |
1977年 | 21507篇 |
1976年 | 21251篇 |
1975年 | 19967篇 |
1974年 | 19633篇 |
1973年 | 20035篇 |
1972年 | 14547篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
Large fault-tolerant interconnection networks 总被引:5,自引:0,他引:5
This paper deals with reliability and fault-tolerant properties of networks. We first survey general reliability properties of networks, in particular those concerning diameter vulnerability. Then we study in details reliability properties of some families of networks in particular de Bruijn and Kautz networks and their generalizations which appear as very good fault-tolerant networks. 相似文献
892.
W. Richard Strark 《Mathematical Logic Quarterly》1989,35(4):311-320
893.
894.
V. V. Tokarchuk 《Journal of Applied Mathematics and Mechanics》1989,53(6):708-715
The Langevin dynamics and fluctuational-dissipative relationships for the hydrodynamic fluctuations for systems which are described in the third Barnett order with respect to the gradients of the hydrodynamic variables are generalized on the basis of a kinetic approach. 相似文献
895.
896.
897.
898.
899.
C. Ghezzi E. Gombia R. Mosca M. Pillan 《Applied Physics A: Materials Science & Processing》1989,48(5):457-463
Capacitance DLTS measurements have been performed in VPE GaAs MESFETs prepared on Bridgman Cr-doped and LEC undoped semi-insulating substrates. A band of electron traps not intrinsically related to the VPE growth process and accumulating near the metal (gate) — semiconductor interface was detected in all the samples. Deeper regions into the channel were free from any detectable trap. Near pinch-off conditions, a positive capacitance signal was found to dominate the DLTS spectra only in the case of samples prepared on Cr-doped substrates. The hypothesis of this positive transient being related to changes in the occupation of surface states in the ungated surface access regions has been checked by comparing experimental and calculated dependencies of the signal amplitude on reverse gate voltage. Unexplained discrepancies, together with the absence of positive signal in MESFETs prepared on LEC undoped substrates, suggest the possibility of hole emission from hole traps within the bulk of the device. 相似文献
900.
Bernard Chazelle Herbert Edelsbrunner Leonidas J. Guibas 《Discrete and Computational Geometry》1989,4(1):139-181
This paper investigates the combinatorial and computational aspects of certain extremal geometric problems in two and three dimensions. Specifically, we examine the problem of intersecting a convex subdivision with a line in order to maximize the number of intersections. A similar problem is to maximize the number of intersected facets in a cross-section of a three-dimensional convex polytope. Related problems concern maximum chains in certain families of posets defined over the regions of a convex subdivision. In most cases we are able to prove sharp bounds on the asymptotic behavior of the corresponding extremal functions. We also describe polynomial algorithms for all the problems discussed.Bernard Chazelle wishes to acknowledge the National Science Foundation for supporting this research in part under Grant No. MCS83-03925. Herbert Edelsbrunner is pleased to acknowledge the support of Amoco Fnd. Fac. Dev. Comput. Sci. 1-6-44862. 相似文献