全文获取类型
收费全文 | 1336篇 |
免费 | 73篇 |
国内免费 | 1篇 |
专业分类
化学 | 996篇 |
晶体学 | 2篇 |
力学 | 24篇 |
数学 | 199篇 |
物理学 | 189篇 |
出版年
2023年 | 32篇 |
2022年 | 17篇 |
2021年 | 32篇 |
2020年 | 55篇 |
2019年 | 64篇 |
2018年 | 29篇 |
2017年 | 33篇 |
2016年 | 68篇 |
2015年 | 60篇 |
2014年 | 48篇 |
2013年 | 55篇 |
2012年 | 97篇 |
2011年 | 90篇 |
2010年 | 54篇 |
2009年 | 34篇 |
2008年 | 59篇 |
2007年 | 78篇 |
2006年 | 72篇 |
2005年 | 75篇 |
2004年 | 54篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 18篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 3篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1973年 | 11篇 |
1969年 | 3篇 |
1968年 | 3篇 |
1934年 | 3篇 |
1932年 | 3篇 |
排序方式: 共有1410条查询结果,搜索用时 39 毫秒
101.
In real-world applications of optimization, optimal solutions are often of limited value, because disturbances of or changes to input data may diminish the quality of an optimal solution or even render it infeasible. One way to deal with uncertain input data is robust optimization, the aim of which is to find solutions which remain feasible and of good quality for all possible scenarios, i.e., realizations of the uncertain data. For single objective optimization, several definitions of robustness have been thoroughly analyzed and robust optimization methods have been developed. In this paper, we extend the concept of minmax robustness (Ben-Tal, Ghaoui, & Nemirovski, 2009) to multi-objective optimization and call this extension robust efficiency for uncertain multi-objective optimization problems. We use ingredients from robust (single objective) and (deterministic) multi-objective optimization to gain insight into the new area of robust multi-objective optimization. We analyze the new concept and discuss how robust solutions of multi-objective optimization problems may be computed. To this end, we use techniques from both robust (single objective) and (deterministic) multi-objective optimization. The new concepts are illustrated with some linear and quadratic programming instances. 相似文献
102.
103.
104.
105.
Mina Mazzeo Marina Lamberti Ilaria D'Auria Stefano Milione Jonas C. Peters Claudio Pellecchia 《Journal of polymer science. Part A, Polymer chemistry》2010,48(6):1374-1382
New Group 3 metal complexes of the type [LM(CH2SiMe3)2(THF)n] supported by tridentate phosphido‐diphosphine ligands [(o‐C6H4PR2) 2 PH; L1‐H : R = iPr; L2‐H : R = Ph] have been synthesized by reaction of L1‐H and L2‐H with [M(CH2SiMe3)3(THF)2)] (M = Y and Sc). All the new complexes [(o‐C6H4PR2) 2 PM(CH2SiMe3)2(THF)n] [M = Y, R = iPr (1), R = Ph (2); M = Sc, R = iPr (3), R = Ph (4)] were studied as initiators for the ring opening polymerization of lactide. The yttrium complexes ( 1 and 2 ) exhibited high activity and good polymerization control, shown by the linear fits in the plot of number‐averaged molecular weight (Mn) versus the percentage conversion and versus the monomer/initiator ratio and by the low polydispersity index values. Interestingly, very good molar‐mass control was observed even when L ‐Lactide was polymerized in the absence of solvent at 130 °C. A good molar‐mass control but lower activities were observed in the polymerization reaction of lactide promoted by the analogous scandium complexes 3 and 4 . © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1374–1382, 2010 相似文献
106.
107.
Jonas Sjöstrand 《Journal of Combinatorial Theory, Series A》2007,114(7):1182-1198
We characterise the permutations π such that the elements in the closed lower Bruhat interval [id,π] of the symmetric group correspond to non-taking rook configurations on a skew Ferrers board. It turns out that these are exactly the permutations π such that [id,π] corresponds to a flag manifold defined by inclusions, studied by Gasharov and Reiner.Our characterisation connects the Poincaré polynomials (rank-generating function) of Bruhat intervals with q-rook polynomials, and we are able to compute the Poincaré polynomial of some particularly interesting intervals in the finite Weyl groups An and Bn. The expressions involve q-Stirling numbers of the second kind, and for the group An putting q=1 yields the poly-Bernoulli numbers defined by Kaneko. 相似文献
108.
In this paper we derive upper and lower bounds on the homogenized energy density functional corresponding to degenerated p-Poisson equations. Moreover, we give some non-trivial examples where the bounds are tight and thus can be used as good approximations of the homogenized properties. We even present some cases where the bounds coincide and also compare them with some numerical results. 相似文献
109.
110.