全文获取类型
收费全文 | 5718篇 |
免费 | 1575篇 |
国内免费 | 444篇 |
专业分类
化学 | 1883篇 |
晶体学 | 36篇 |
力学 | 826篇 |
综合类 | 65篇 |
数学 | 364篇 |
物理学 | 4563篇 |
出版年
2024年 | 10篇 |
2023年 | 42篇 |
2022年 | 145篇 |
2021年 | 189篇 |
2020年 | 170篇 |
2019年 | 178篇 |
2018年 | 167篇 |
2017年 | 256篇 |
2016年 | 289篇 |
2015年 | 271篇 |
2014年 | 412篇 |
2013年 | 443篇 |
2012年 | 409篇 |
2011年 | 419篇 |
2010年 | 293篇 |
2009年 | 326篇 |
2008年 | 385篇 |
2007年 | 385篇 |
2006年 | 361篇 |
2005年 | 327篇 |
2004年 | 241篇 |
2003年 | 266篇 |
2002年 | 226篇 |
2001年 | 213篇 |
2000年 | 188篇 |
1999年 | 161篇 |
1998年 | 124篇 |
1997年 | 117篇 |
1996年 | 112篇 |
1995年 | 80篇 |
1994年 | 73篇 |
1993年 | 64篇 |
1992年 | 57篇 |
1991年 | 43篇 |
1990年 | 43篇 |
1989年 | 38篇 |
1988年 | 29篇 |
1987年 | 35篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 20篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有7737条查询结果,搜索用时 15 毫秒
71.
72.
SHI Bingren LI Jiquan DONG Jiaqi 《核工业西南物理研究院年报(英文版)》2004,(1):115-118
The geodesic acoustic mode (GAM), first predicted by Winsor, Johnson and Dawson in an attempt to explain some experimentally observed low frequency oscillations in stellarators, is a special electrostatic fluid mode with low mode number and coupled with the so-called geodesic curvature of a toroidally confined plasma. The recent on this mode are due to the close relevance of the stabi- lization of drift turbulence by both the zonal flow and the GAM. Previously, the GAM was illustrated in very simple geometries, 相似文献
73.
I. Capek J. Chudej S. Janí
kov 《Journal of polymer science. Part A, Polymer chemistry》2003,41(6):804-820
The sterically stabilized emulsion polymerization of styrene initiated by a water‐soluble initiator at different temperatures has been investigated. The rate of polymerization (Rp) versus conversion curve shows the two non‐stationary‐rate intervals typical for the polymerization proceeding under non‐stationary‐state conditions. The shape of the Rp versus conversion curve results from two opposite effects—the increased number of particles and the decreased monomer concentration at reaction loci as the polymerization advances. At elevated temperatures the monomer emulsion equilibrates to a two‐phase or three‐phase system. The upper phase is transparent (monomer), and the lower one is blue colored, typical for microemulsion. After stirring such a multiphase system and initiation of polymerization, the initial coarse polymer emulsion was formed. The average size of monomer/polymer particles strongly decreased up to about 40% conversion and then leveled off. The initial large particles are assumed to be highly monomer‐swollen particles formed by the heteroagglomeration of unstable polymer particles and monomer droplets. The size of the “highly monomer” swollen particles continuously decreases with conversion, and they merge with the growing particles at about 40–50% conversion. The monomer droplets and/or large highly monomer‐swollen polymer particles also serve as a reservoir of monomer and emulsifier. The continuous release of nonionic (hydrophobic) emulsifier from the monomer phase increases the colloidal stability of primary particles and the number of polymer particles, that is, the particle nucleation is shifted to the higher conversion region. Variations of the square and cube of the mean droplet radius with aging time indicate that neither the coalescence nor the Ostwald ripening is the main driving force for the droplet instability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 804–820, 2003 相似文献
74.
75.
76.
77.
资源共享方式若干问题的研讨 总被引:3,自引:1,他引:2
社会公用服务系统和工程技术系统,存在共同的资源共享问题。本文通过典例就资源共享方式的若干问题加以探究:讨论广义的多用户系统中人工资源共享方式的分类;阐述常用的共享方式的特点、优缺点;分析系统时间性能及其改进与共享方式的关系等。文章还提出在系统工程范畴里,应对社会公用服务和工程技术两类系统的资源共享方式予以综合研究,并相互借鉴和移植。 相似文献
78.
IntroductionThemethoxyradical (CH3O)isanimportantinter mediateinthephotochemicaloxidationofhydrocarbonsintheatmosphere ,1 3andplaysasignificantroleintrans formingnitricoxidetonitrogendioxide .4 Similarly ,thereactionmechanismsofhydroxylandcarbonmonoxide5,6ando… 相似文献
79.
分离变量法与等腰直角三角形波导的边值问题 总被引:4,自引:0,他引:4
根据叠加原理,讨论等腰直角三角形波导边值问题的IE波解和TM波解,纠正有关文献中的错误解法,指出分离变量法的适用条件。 相似文献
80.
Spatio temporal dynamics of the positive column of a dc neon glow discharge is studied and investigated experimentally and theoretically. Spatio temporal analysis by means of biorthogonal decomposition method (BOD) gives insights into the mechanism of irregularity and can be employed for characterization of spatio‐ temporal complexity. In the weak nonlinear region, the wave dynamics is approximated by an amplitude equation of the Ginzburg‐Landau equation (CGLE) with complex coefficients and an additional integral term based on a fluid model. In the present work we deal with irregular spatio‐temporal data. A comparison between the numerical analysis of the experimental data and simulation results are studied. A good agreement between the dynamical behaviour for experimental space‐time data and theoretical simulation space‐time results was obtained. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献