全文获取类型
收费全文 | 176323篇 |
免费 | 574篇 |
国内免费 | 133篇 |
专业分类
化学 | 73506篇 |
晶体学 | 2572篇 |
力学 | 10415篇 |
综合类 | 1篇 |
数学 | 32445篇 |
物理学 | 58091篇 |
出版年
2021年 | 870篇 |
2020年 | 966篇 |
2019年 | 1105篇 |
2018年 | 10330篇 |
2017年 | 11199篇 |
2016年 | 6185篇 |
2015年 | 1851篇 |
2014年 | 1844篇 |
2013年 | 3394篇 |
2012年 | 7265篇 |
2011年 | 15922篇 |
2010年 | 9753篇 |
2009年 | 9887篇 |
2008年 | 13734篇 |
2007年 | 17311篇 |
2006年 | 2966篇 |
2005年 | 9164篇 |
2004年 | 5682篇 |
2003年 | 5619篇 |
2002年 | 3609篇 |
2001年 | 2403篇 |
2000年 | 1960篇 |
1999年 | 1294篇 |
1998年 | 1173篇 |
1997年 | 1054篇 |
1996年 | 1079篇 |
1995年 | 940篇 |
1994年 | 906篇 |
1993年 | 897篇 |
1992年 | 938篇 |
1991年 | 1014篇 |
1990年 | 955篇 |
1989年 | 991篇 |
1988年 | 913篇 |
1987年 | 860篇 |
1986年 | 822篇 |
1985年 | 961篇 |
1984年 | 1074篇 |
1983年 | 919篇 |
1982年 | 930篇 |
1981年 | 833篇 |
1980年 | 782篇 |
1979年 | 867篇 |
1978年 | 997篇 |
1977年 | 936篇 |
1976年 | 868篇 |
1975年 | 815篇 |
1974年 | 830篇 |
1973年 | 847篇 |
1972年 | 591篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
V. O. Tarasov 《Journal of Mathematical Sciences》1991,54(3):958-967
A mixed boundary-value problem for the nonlinear Schrödinger equation and its generalization is studied by the method used for the inverse scattering problem. A connection is established between conservation laws and boundary conditions in integrable boundary-value problems for higher nonlinear Schrödinger equations. It is shown that the generalized boundary-value problem requires a joint consideration of regular and singular solutions for the nonlinear Schrödinger equation with repulsion.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 169, pp. 151–165, 1988. 相似文献
92.
93.
J. Berny 《The Journal of the Operational Research Society》1989,40(12):1121-1127
This paper presents an alternative to the beta continuous probability distribution for risk analysis. Particular attention has been given to two major applications of distributions, namely project management risk and critical path analysis (PERT). In conjunction with the beta, the triangular and normal distributions are frequently employed in order to give sufficient robustness to risk analysis. The beta distribution, as used in PERT, has a major theoretical implementation flaw. The new distribution was developed to give a possible alternative method of assessing risk. It is shown that the requirement to estimate the most pessimistic variate may be replaced by the probability to exceed the mode. Proposals for other simplifications in risk analysis are discussed. Practical means to validate the most appropriate distributions for risk analysis are outlined, and a cost-data case study is included. 相似文献
94.
95.
Summary The main purpose of this paper is to introduce the concepts of η-sets, ηζ-sets,η-continuity and ηζ-continuity and to obtain
a decomposition of continuity. 相似文献
96.
Zarubitskii O. G. Budnik V. G. Omel'chuk A. A. Melekhin V. T. Opanasyuk V. P. Zakharchenko N. F. 《Russian Journal of Applied Chemistry》2002,75(4):558-561
Electrochemical separation of lead-silver alloys into the constituents by thin-layer electrolysis in molten electrolytes, with bismuth as metal separator, is studied. It is proposed to determine the extent of component recovery by potentiometry. 相似文献
97.
Electroactive conducting polymers for corrosion control 总被引:1,自引:0,他引:1
Dennis E. Tallman Geoff Spinks Anton Dominis Gordon G. Wallace 《Journal of Solid State Electrochemistry》2002,6(2):73-84
There is an intensive effort underway to develop new corrosion control coatings for structural metals. In part, this effort
has been motivated by the desire to replace chromium(VI)-containing coatings currently used for corrosion control of iron
and aluminum alloys. Cr(VI) has been shown to be hazardous to the environmental and to human health, and its use in many countries
will be sharply curtailed in the coming years. Electroactive conducting polymers (ECPs) represent a class of interesting materials
currently being explored for use in corrosion control coating systems, possibly as a replacement for Cr(VI)-based coatings.
The electroactivity and the electronic conductivity (or semiconductivity) of ECPs set them apart from traditional organic
coatings. As with chromate, interesting and potentially beneficial interactions of ECPs with active metal alloys such as steel
and aluminum are anticipated, with concomitant alteration of their corrosion behavior. A review of this active research area
will be presented in two parts. Here in Part 1, a general introduction to the topic of corrosion control by ECPs will be presented,
including an overview of corrosion and its control by traditional methods, an introduction to ECPs and their properties, and
a discussion of the processing issues surrounding the use of ECPs as coatings. Part 1 also includes a review of the literature
on the use of ECPs as coatings (or components of coatings) on non-ferrous active metals, principally aluminum and aluminum
alloys, although some work on zinc, copper, silver, titanium and silicon will also be described. In Part 2 of this review
(to be published in the next issue of this journal), the rather extensive literature on the use of ECPs for the corrosion
control of ferrous alloys (steels) will be reviewed.
Electronic Publication 相似文献
98.
Formalization for problems of multicriteria decision making under uncertainty is constructed in terms of guaranteed and weak
estimates. A relevant definition of the vector maximinimax value is given. Parameterization and approximation of maximum,
minimax, and maximinimax values based on the inverse logical convolution are suggested. An application for multicommodity
networks is considered.
Received: December 13, 2000 / Accepted: August 21, 2001?Published online May 8, 2002 相似文献
99.
The procedure for calculating the dispersion of the refractive and absorption indices and thickness of an optical film, based on measurements of spectral dependence of the transmittance, is described. The film parameters are calculated using a solution of the approximation problem. The effect of the film model on the calculated values of the refractive and absorption indices is analyzed. 相似文献
100.