全文获取类型
收费全文 | 1100篇 |
免费 | 99篇 |
国内免费 | 55篇 |
专业分类
化学 | 311篇 |
晶体学 | 17篇 |
力学 | 18篇 |
综合类 | 18篇 |
数学 | 298篇 |
物理学 | 592篇 |
出版年
2024年 | 6篇 |
2023年 | 8篇 |
2022年 | 18篇 |
2021年 | 18篇 |
2020年 | 31篇 |
2019年 | 41篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 32篇 |
2015年 | 46篇 |
2014年 | 69篇 |
2013年 | 118篇 |
2012年 | 55篇 |
2011年 | 53篇 |
2010年 | 57篇 |
2009年 | 59篇 |
2008年 | 61篇 |
2007年 | 76篇 |
2006年 | 55篇 |
2005年 | 49篇 |
2004年 | 33篇 |
2003年 | 48篇 |
2002年 | 39篇 |
2001年 | 22篇 |
2000年 | 29篇 |
1999年 | 30篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 30篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1254条查询结果,搜索用时 15 毫秒
161.
Guang‐Hui Ma Junichiro Fujiwara Zhi‐Guo Su Shinzo Omi 《Journal of polymer science. Part A, Polymer chemistry》2003,41(16):2588-2598
A highly crosslinked poly(styrene–divinyl benzene–trimethyolpropane trimethacrylate) microsphere containing a polyimide prepolymer (PIP) was prepared by a new emulsification method, Shirasu porous glass (SPG) membrane emulsification, and a subsequent radical suspension polymerization. That is, a mixture of styrene, divinyl benzene, trimethyol propane trimethacrylate (TMPTMA), and PIP containing an initiator was permeated through the uniform pores of the SPG membrane into a continuous phase containing a stabilizer to form uniform droplets. Then, the suspension polymerization was carried out at 65 °C for 24 h. The trifunctional crosslinker TMPTMA was added to enhance the destructive strength of the microsphere, and PIP was incorporated into the microsphere to provide an adhesion force by a known self‐curing reaction at 220 °C. The effects of the feed amounts of TMPTMA and PIP on the monomer conversion, size distribution, and destructive strength of the microsphere were investigated. The monomer conversion increased with an increase in TMPTMA. The particle size distribution became narrower as the TMPTMA feed amount increased, but it became broader with an increase in PIP. The destructive strength increased with increases in TMPTMA and PIP. After a heat treatment at 220 °C, the destructive strength decreased because of the heat degradation of the polymer. The addition of TMPTMA suppressed the heat degradation, and PIP could undergo self‐curing at 220 °C. The obtained highly crosslinked uniform microsphere containing PIP has potential applications in liquid‐crystal displays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2588–2598, 2003 相似文献
162.
163.
Abdellah Bnouhachem Muhammad Aslam Noor 《Journal of Mathematical Analysis and Applications》2006,324(2):1195-1212
In this paper, we suggest and analyze a new inexact proximal point method for solving general variational inequalities, which can be considered as an implicit predictor-corrector method. An easily measurable error term is proposed with further relaxed error bound and an optimal step length is obtained by maximizing the profit-function and is dependent on the previous points. Our results include several known and new techniques for solving variational inequalities and related optimization problems. Results obtained in this paper can be viewed as an important improvement and refinement of the previously known results. Preliminary numerical experiments are included to illustrate the advantage and efficiency of the proposed method. 相似文献
164.
本文简要介绍了军用光电侦察装备在现代军事侦察中的作用和地位,几种主要军用光电侦察装备的发展趋势,提出了应该采取的技术对策和重点研究的课题。 相似文献
165.
本文叙述了一个求解线性规划问题的梯度投影法,导出了投影矩阵的递推公式,利用此公式可大大减少每次迭代所需的计算量。实例计算表明,本文给出的算法是一有效的算法,在某些方面它要优于Karmarkar算法和单纯形法。 相似文献
166.
167.
How good are projection methods for convex feasibility problems? 总被引:2,自引:0,他引:2
We consider simple projection methods for solving convex feasibility problems. Both successive and sequential methods are
considered, and heuristics to improve these are suggested. Unfortunately, particularly given the large literature which might
make one think otherwise, numerical tests indicate that in general none of the variants considered are especially effective
or competitive with more sophisticated alternatives.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.
This work was supported by the EPSRC grant GR/S42170. 相似文献
168.
In a previous work (Ref. 1), we examined some active set methods for the computation of the projection of a point onto a polyhedron when a feasible point is known. In this paper, we assume that such a point is not known and examine a method similar to the big-M method developed for the solution of linear programming problems. Special attention is given to the study of computing error propagation.This research was supported partially by the Progetto Finalizzato Informatica del CNR, Sottoprogetto P1, Sofmat. 相似文献
169.
Stephen I. McConnell Albert J. Uveges Dana M. Fowlkes Dominic G. Spinella 《Molecular diversity》1996,1(3):165-176
Summary We have constructed two phage display libraries expressing N-terminal pIII fusions in M13 composed of 37 and 43 random amino acid domains, respectively. The D38 library expresses 37 random amino acids with a central alanine residue, and the DC43 library contains 43 random amino acids with a central cysteine flanked by two glycine residues, giving the displayed peptide the potential to form disulfide loops of various sizes. We demonstrate that the majority of random sequences in both libraries are compatible in pentavalent display with phage viability. The M13 phage display vector itself has been engineered to contain a factor Xa protease cleavage site to provide an alternative to acid elution during affinity selection. An in-frame amber mutation has been inserted between the pIII cloning sites to allow for efficient selection against nonrecombinant phage in the library. These libraries have been panned against mAb 7E11-C5, which recognizes the prostate-specific membrane antigen (PSM). Isolated phage display a consensus sequence that is homologous to a region in the PSM molecule. 相似文献
170.
G. Pierra 《Mathematical Programming》1984,28(1):96-115
When an optimization problem is posed in a product space it is classical to decompose this problem. The goal of this paper
is to show how such an approach can be used when the problem to be solved is not naturally posed in a product space. By associating
systematically to this problem an equivalent one posed in ann-fold cartesian product space, we obtain by decomposition of the latter both a splitting of operators and a desintegration
of constraints for the former. Applications to three rather classical mathematical programming problems are given. 相似文献