全文获取类型
收费全文 | 1734篇 |
免费 | 55篇 |
国内免费 | 11篇 |
专业分类
化学 | 1117篇 |
晶体学 | 23篇 |
力学 | 46篇 |
数学 | 313篇 |
物理学 | 301篇 |
出版年
2023年 | 9篇 |
2022年 | 28篇 |
2021年 | 43篇 |
2020年 | 27篇 |
2019年 | 40篇 |
2018年 | 21篇 |
2017年 | 20篇 |
2016年 | 61篇 |
2015年 | 56篇 |
2014年 | 58篇 |
2013年 | 84篇 |
2012年 | 121篇 |
2011年 | 124篇 |
2010年 | 70篇 |
2009年 | 69篇 |
2008年 | 96篇 |
2007年 | 119篇 |
2006年 | 95篇 |
2005年 | 101篇 |
2004年 | 95篇 |
2003年 | 73篇 |
2002年 | 64篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 22篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 19篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1960年 | 5篇 |
1911年 | 2篇 |
排序方式: 共有1800条查询结果,搜索用时 0 毫秒
1.
2.
Mauro Picone 《Rendiconti del Circolo Matematico di Palermo》1997,46(1):437-455
[Estratto da una lettera al Prof. G. Bagnera] 相似文献
3.
4.
We consider the generalization of the classical P||Cmax problem (assign n jobs to m identical parallel processors by minimizing the makespan) arising when the number of jobs that can be assigned to each processor cannot exceed a given integer k. The problem is strongly NP-hard for any fixed k > 2. We briefly survey lower and upper bounds from the literature. We introduce greedy heuristics, local search and a scatter search approach. The effectiveness of these approaches is evaluated through extensive computational comparison with a depth-first branch-and-bound algorithm that includes new lower bounds and dominance criteria. 相似文献
5.
Some authors claim that reporting the best result obtained by a stochastic algorithm in a number of runs is more meaningful
than reporting some central statistic. In this short note, we analyze and refute the main argument brought in favor of this
statement. 相似文献
6.
In this paper we study a Ginzburg–Landau model which describes the behaviour of a superconducting material including thermal effects. We extend the traditional formulation of the problem, by introducing the temperature as an additional state variable. Accordingly, together with the Gor’kov–Eliashberg system, we introduce an evolution equation for the absolute temperature. We examine in detail the case which allows only variations of the concentration of superconducting electrons and of the temperature, neglecting the electromagnetic field. For this problem existence and uniqueness of the solution are shown. Finally we analyze the asymptotic behaviour of the solutions, proving that the system possesses a global attractor. 相似文献
7.
In this work we show that the energy associated to the linear three-dimensional magneto-elastic system decays polynomially to zero as time goes to infinity, provided the initial data is smooth enough. 相似文献
8.
The hyperreal numbers of nonstandard analysis are characterized in purely algebraic terms as homomorphic images of a suitable class of rings of functions.
9.
10.
Commisso R.J. Apruzese J.P. Black D.C. Boller J.R. Moosman B. Mosher D. Stephanakis S.J. Weber B.V. Young F.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(4):1068-1085
The K-shell radiated energy (yield) from neon Z-pinch implosions with annular, gas-puff nozzle radii of 1, 1.75, and 2.5 cm was measured for implosion times from 50 to 300 ns while systematically keeping the implosion kinetic energy nearly constant. The implosions were driven by the Hawk inductive-storage generator at the 0.65-MA level. Initial neutral-neon density distributions from the nozzles were determined with laser interferometry. Measured yields are compared with predictions from zero-dimensional (0-D) scaling models of ideal. One-dimensional (1-D) pinch behavior to both benchmark the scaling models, and to determine their utility for predicting K-shell yields for argon implosions of 200 to >300 ns driven by corresponding currents of 4 to 9 MA, such as envisioned for the DECADE QUAD. For all three nozzles, the 0-D models correctly predict the Z-pinch mass for maximum yield. For the 1and 1.75-cm radius nozzles, the scaling models accurately match the measured yields if the ratio of initial to final radius (compression ratio) is assumed to be 8:1. For the 2.5-cm radius nozzle, the measured yields are only one-third of the predictions. Analysis of K-shell spectral measurements suggest that as much as 70% (50%) of the imploded mass is radiating in the K-shell for the 1-cm (1.75-cm) radius nozzle. That fraction is only 10% for the 2.5-cm radius nozzle. The 0-D scaling models are useful for predicting 1-D-like K-shell radiation yields (better than a factor-of-two accuracy) when a nominal (≈10:1) compression ratio is assumed. However, the compression ratio assumed in the models is only an “effective” quantity, so that further interpretations based on the 0-D analysis require additional justification. The lower-than-predicted yield for the 2.5-cm radius nozzle is associated with larger radius and not with longer implosion time, and is probably a result of two-dimensional effects 相似文献