全文获取类型
收费全文 | 3093篇 |
免费 | 97篇 |
国内免费 | 2篇 |
专业分类
化学 | 1911篇 |
晶体学 | 45篇 |
力学 | 93篇 |
数学 | 644篇 |
物理学 | 499篇 |
出版年
2023年 | 18篇 |
2022年 | 49篇 |
2021年 | 81篇 |
2020年 | 72篇 |
2019年 | 90篇 |
2018年 | 117篇 |
2017年 | 111篇 |
2016年 | 142篇 |
2015年 | 135篇 |
2014年 | 161篇 |
2013年 | 392篇 |
2012年 | 191篇 |
2011年 | 199篇 |
2010年 | 200篇 |
2009年 | 151篇 |
2008年 | 190篇 |
2007年 | 172篇 |
2006年 | 127篇 |
2005年 | 81篇 |
2004年 | 73篇 |
2003年 | 48篇 |
2002年 | 48篇 |
2001年 | 28篇 |
2000年 | 26篇 |
1999年 | 22篇 |
1998年 | 18篇 |
1997年 | 14篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 17篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 17篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1975年 | 5篇 |
1974年 | 11篇 |
1973年 | 9篇 |
1968年 | 9篇 |
排序方式: 共有3192条查询结果,搜索用时 31 毫秒
1.
2.
Condeixa Lucas Dias Silva Pierry Moah Diego Farias Brenda Leiras Adriana 《Central European Journal of Operations Research》2022,30(3):921-940
Central European Journal of Operations Research - Societal awareness and legislation changes concerning sustainability have affected how organizations generate value for stakeholders, as well as... 相似文献
3.
In this study, stoichiometric protonation constants of L-tyrosine, L-cysteine, L-tryptophane, L-lysine, and L-histidine, and
their methyl and ethyl esters in water and ethanol–water mixtures of 30, 50, and 70% ethanol (v/v), were determined potentiometrically
using a combined pH electrode system calibrated as the concentration of hydrogen ion. Titrations were performed at 25∘C and the ionic strength of the medium was maintained at 0.10 mol⋅L−1 using sodium chloride. Protonation constants were calculated by using the BEST computer program. The effect of solvent composition
on the protonation constants is discussed. The log10 K2 values of esters generally decreased with increasing ethanol content. However, the log10 K1 values of the esters of L-tyrosine, L-cysteine, and L-tryptophane were found to increase with increasing ethanol content
in contrast those of L-lysine and L-histidine esters. 相似文献
4.
Suppose there exists a global solution u to the incompressible Navier–Stokes equations, such that . We prove that its norm goes to 0 at infinity. We next use this fact to control the norm of u, and finally we prove that such a solution is stable. To cite this article: I. Gallagher et al., C. R. Acad. Sci. Paris, Ser. I 334 (2002) 289–292. 相似文献
5.
Stefan Cobzaş 《Acta Appl Math》2004,80(3):363-363
6.
Alvim Adriana C.F. Ribeiro Celso C. Glover Fred Aloise Dario J. 《Journal of Heuristics》2004,10(2):205-229
We propose in this work a hybrid improvement procedure for the bin packing problem. This heuristic has several features: the use of lower bounding strategies; the generation of initial solutions by reference to the dual min-max problem; the use of load redistribution based on dominance, differencing, and unbalancing; and the inclusion of an improvement process utilizing tabu search. Encouraging results have been obtained for a very wide range of benchmark instances, illustrating the robustness of the algorithm. The hybrid improvement procedure compares favourably with all other heuristics in the literature. It improved the best known solutions for many of the benchmark instances and found the largest number of optimal solutions with respect to the other available approximate algorithms. 相似文献
7.
Mustafa Çelebier Ertan Şahin Nilgün Ancın Nurşen Altuntaş Öztaş Selma Gül Öztaş 《应用有机金属化学》2007,21(10):viii-viii
The article referenced above was first published online on 30 August 2007 with incorrect pagination; the pagination has now been corrected online and in print. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
8.
We continue the studies on the so–called genuine Bernstein–Durrmeyer operators U
n
by establishing a recurrence formula for the moments and by investigating the semigroup T(t) approximated by U
n
. Moreover, for sufficiently smooth functions the degree of this convergence is estimated. We also determine the eigenstructure
of U
n
, compute the moments of T(t) and establish asymptotic formulas.
Received: January 26, 2007. 相似文献
9.
Adriana Tudose 《Tetrahedron letters》2006,47(48):8529-8533
Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product. 相似文献
10.
We give a concise review and extension of S-procedure that is an instrumental tool in control theory and robust optimization analysis. We also discuss the approximate S-Lemma as well as its applications in robust optimization.The many suggestions and detailed corrections of an anonymous referee are gratefully acknowledged. 相似文献