全文获取类型
收费全文 | 298262篇 |
免费 | 2713篇 |
国内免费 | 676篇 |
专业分类
化学 | 141826篇 |
晶体学 | 4162篇 |
力学 | 11922篇 |
综合类 | 9篇 |
数学 | 29480篇 |
物理学 | 82813篇 |
无线电 | 31439篇 |
出版年
2019年 | 2501篇 |
2018年 | 3384篇 |
2017年 | 3340篇 |
2016年 | 4809篇 |
2015年 | 2799篇 |
2014年 | 4642篇 |
2013年 | 11269篇 |
2012年 | 8468篇 |
2011年 | 10389篇 |
2010年 | 7608篇 |
2009年 | 7777篇 |
2008年 | 10482篇 |
2007年 | 10982篇 |
2006年 | 10227篇 |
2005年 | 9427篇 |
2004年 | 8730篇 |
2003年 | 7937篇 |
2002年 | 7869篇 |
2001年 | 8479篇 |
2000年 | 6845篇 |
1999年 | 5413篇 |
1998年 | 4938篇 |
1997年 | 4903篇 |
1996年 | 4517篇 |
1995年 | 4245篇 |
1994年 | 4343篇 |
1993年 | 4023篇 |
1992年 | 4445篇 |
1991年 | 4513篇 |
1990年 | 4378篇 |
1989年 | 4158篇 |
1988年 | 4180篇 |
1987年 | 3818篇 |
1986年 | 3613篇 |
1985年 | 4688篇 |
1984年 | 4970篇 |
1983年 | 4166篇 |
1982年 | 4258篇 |
1981年 | 4191篇 |
1980年 | 4133篇 |
1979年 | 4075篇 |
1978年 | 4392篇 |
1977年 | 4307篇 |
1976年 | 4369篇 |
1975年 | 4014篇 |
1974年 | 4091篇 |
1973年 | 4242篇 |
1972年 | 3010篇 |
1971年 | 2499篇 |
1970年 | 2307篇 |
排序方式: 共有10000条查询结果,搜索用时 812 毫秒
991.
R. Hart P. Hue D. Burton G. F. Robertshaw F. G. H. Tate L. A. Warren und P. Eisenstein 《Fresenius' Journal of Analytical Chemistry》1938,115(7-8):272-274
Ohne Zusammenfassung 相似文献
992.
993.
994.
V. I. Naryshkin G. M. Strelkov A. M. Ryazantsev 《Journal of Communications Technology and Electronics》2008,53(7):782-787
Deformation and attenuation of an ultrawideband radio pulse propagating along a single-wire line are analyzed as functions of the pulse initial duration. Variations in the longitudinal and transverse components of the pulse electric field with the distance from the line are determined. Features of the spatial distribution of the energy carried by the pulse near the line are revealed. 相似文献
995.
Russomanno D.J. de Jongh Curry A.L. Atanasova G.S. Hunt L.C. Goodwin J.C. 《IEEE transactions on information technology in biomedicine》2008,12(1):76-86
DefibViz is a software application developed for defibrillation simulation and visualization. It exploits both surface techniques and methods for the interactive exploration of volumetric datasets for the analysis of transthoracic defibrillation simulation results. DefibViz has a graphical user interface for the specification of the shape, size, position, and applied voltage of a defibrillator's electrodes. An option is provided for using 3D slice plane widgets, which operate on the volumetric datasets, such that the distribution of the voltage gradient induced by an electric shock can be visually inspected in various tissues throughout the myocardium and torso. One goal of DefibViz is to enhance understanding of how electrode parameters relate to the change of the voltage gradient distribution throughout the heart, which may help lead to optimal defibrillator design. DefibViz is significant, in that, it is built by using an open-source graphics and visualization framework providing a platform for subsequent modifiability and extensibility. Moreover, it integrates simulation and visualization techniques, which previously required the running of several independent software executables, into an enhanced, seamless, and comprehensive software application. 相似文献
996.
997.
The article proposes an analytical method for determining occupancy distribution and blocking probability in systems which are offered overflow traffic composed of multi-service traffic streams. The described analytical model enables determination of parameters of traffic overflowed from primary groups in hierarchically constructed telecommunication networks. The proposed method is based on an appropriate modification of the Kaufman-Roberts recursion for the full-availability group with multi-rate traffic and uses the modified Fredericks & Hayward’s approximation. Additionally, an approximate method for dimensioning systems with multi-service overflow traffic is also presented. The analytical results of the blocking probability and the results obtained in the dimensioning processes calculated using the presented methodology are compared with the data obtained from the system simulation process. 相似文献
998.
A. Craig W. H. Jacobson A. Meyer N. Welwart A. Seuthe H. N. Marr B. S. Evans G. E. F. Lundell J. A. Scherrer E. Stelling F. J. Mück A. Kling A. Lassieur L. Bertiaux C. C. Bissett P. de Pauw J. Heslinga A. Bartsch R. E. Lee W. H. Fegeley F. H. Reichel und E. Saz 《Fresenius' Journal of Analytical Chemistry》1927,71(1-2):83-90
Ohne Zusammenfassung 相似文献
999.
1000.
We consider the support problem of Erdös in the context of l-adic representations of the absolute Galois group of a number field. Main applications of the results of the paper concern Galois cohomology of the Tate module of abelian varieties with real and complex multiplications, the algebraic K-theory groups of number fields and the integral homology of the general linear group of rings of integers. We answer the question of Corrales-Rodrigáñez and Schoof concerning the support problem for higher dimensional abelian varieties. 相似文献