全文获取类型
收费全文 | 2909篇 |
免费 | 258篇 |
国内免费 | 262篇 |
专业分类
化学 | 698篇 |
晶体学 | 3篇 |
力学 | 222篇 |
综合类 | 46篇 |
数学 | 1824篇 |
物理学 | 636篇 |
出版年
2024年 | 8篇 |
2023年 | 28篇 |
2022年 | 123篇 |
2021年 | 114篇 |
2020年 | 124篇 |
2019年 | 93篇 |
2018年 | 77篇 |
2017年 | 92篇 |
2016年 | 65篇 |
2015年 | 90篇 |
2014年 | 139篇 |
2013年 | 214篇 |
2012年 | 126篇 |
2011年 | 173篇 |
2010年 | 119篇 |
2009年 | 220篇 |
2008年 | 188篇 |
2007年 | 195篇 |
2006年 | 158篇 |
2005年 | 130篇 |
2004年 | 137篇 |
2003年 | 119篇 |
2002年 | 91篇 |
2001年 | 65篇 |
2000年 | 69篇 |
1999年 | 76篇 |
1998年 | 80篇 |
1997年 | 67篇 |
1996年 | 48篇 |
1995年 | 39篇 |
1994年 | 43篇 |
1993年 | 21篇 |
1992年 | 21篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有3429条查询结果,搜索用时 15 毫秒
31.
32.
Ali. Elamin. M. Saeed 《Annals of Differential Equations》2006,22(2):127-133
The purpose of this paper is to study a general Lienard type cubic system with one antisaddle and two saddles. We give some results of the existence and uniqueness of limit cycles as well as the evolution of limit cycles around the antisaddle for system (2) in the following when parameter a1 changes. 相似文献
33.
Multi-dimensional asymptotically quasi-Toeplitz Markov chains with discrete and continuous time are introduced. Ergodicity
and non-ergodicity conditions are proven. Numerically stable algorithm to calculate the stationary distribution is presented.
An application of such chains in retrial queueing models with Batch Markovian Arrival Process is briefly illustrated.
AMS Subject Classifications Primary 60K25 · 60K20 相似文献
34.
Mark Pollicott 《Topology and its Applications》2007,154(12):2365-2375
We study lifts of the stable foliation of a pseudo-Anosov diffeomorphism to abelian covers. Under certain conditions, we show that it is ergodic but not uniquely ergodic and describe the ergodic measures. 相似文献
35.
“Optimization of aircraft maintenance/support infrastructure using genetic algorithms—level of repair analysis” 总被引:4,自引:0,他引:4
Level of repair analysis (LORA) is an approach used during the design stage of complex equipment for analysis of the cost
effectiveness of competing maintenance strategies. LORA is carried as a part of the life cycle cost and cost of ownership
analysis and plays a significant role in minimizing the life cycle cost and cost of ownership of the capital equipment. Since
many purchasing decisions of complex equipment are based on cost of ownership, it has become essential to carry out LORA to
compete in the market. In this paper, we develop a mathematical model for LORA and propose a solution methodology based on
genetic algorithms. The concept is illustrated using a hypothetical aircraft engine. 相似文献
36.
Hidefumi Ohsugi 《Journal of Combinatorial Theory, Series A》2006,113(4):718-725
Athanasiadis [Ehrhart polynomials, simplicial polytopes, magic squares and a conjecture of Stanley, J. Reine Angew. Math., to appear.] studies an effective technique to show that Gorenstein sequences coming from compressed polytopes are unimodal. In the present paper we will use such the technique to find a rich class of Gorenstein toric rings with unimodal h-vectors arising from finite graphs. 相似文献
37.
A method has been developed to determine the boiling point distribution of sulfur compounds in light cycle oils (LCO'S). The method chosen for this analysis was GC with a flame photometric detector (FPD) and pyrolyzer. Tests were carried out to evaluate the recovery efficiency, repeatability, and accuracy of the method. Repeatabilities within 2% were obtained. The recovery of benzothiophenes and dibenzothiophenes was close to 100%; this was important because these are the major sulfur components in LCO's. No hydrocarbon or solvent interferences were observed with the use of the pyrolyzer, even for a 95% solvent level. Comparison with results from other techniques showed that the method accurately determined the levels of sulfur compounds in the LCO boiling point range. 相似文献
38.
We describe links between a recently introduced semidefinite relaxation for the max-cut problem and the well known semidefinite
relaxation for the stable set problem underlying the Lovász’s theta function. It turns out that the connection between the
convex bodies defining the semidefinite relaxations mimics the connection existing between the corresponding polyhedra. We
also show how the semidefinite relaxations can be combined with the classical linear relaxations in order to obtain tighter
relaxations.
This work was done while the author visited CWI, Amsterdam, The Netherlands.
Svata Poljak untimely deceased in April 1995. We shall both miss Svata very much. Svata was an excellent colleague, from whom
we learned a lot of mathematics and with whom working was always a very enjoyable experience; above all, Svata was a very
nice person and a close friend of us.
The research was partly done while the author visited CWI, Amsterdam, in October 1994 with a grant fom the Stieltjes Institute,
whose support is gratefully acknowledged. Partially supported also by GACR 0519.
Research support by Christian Doppler Laboratorium für Diskrete Optimierung. 相似文献
39.
排气全燃型联合循环设计点性能简明估计公式 总被引:1,自引:0,他引:1
排气全燃型联合循环设计点性能简明估计公式蔡睿贤(中国科学院工程热物理研究所北京10O080)关键词:排气全燃型联合循环,热力分析主要符号表Hu燃料热值L燃料理论空气量l比功P单位能量价格R燃气轮机与蒸汽轮机的功率比α过量空气系数β摩尔燃料系数△增量η... 相似文献
40.