全文获取类型
收费全文 | 536770篇 |
免费 | 4043篇 |
国内免费 | 1194篇 |
专业分类
化学 | 256477篇 |
晶体学 | 8263篇 |
力学 | 28884篇 |
综合类 | 10篇 |
数学 | 73664篇 |
物理学 | 174709篇 |
出版年
2021年 | 5079篇 |
2020年 | 5401篇 |
2019年 | 6313篇 |
2018年 | 9008篇 |
2017年 | 9292篇 |
2016年 | 12322篇 |
2015年 | 6446篇 |
2014年 | 11446篇 |
2013年 | 24046篇 |
2012年 | 19109篇 |
2011年 | 22612篇 |
2010年 | 17578篇 |
2009年 | 17858篇 |
2008年 | 21014篇 |
2007年 | 20766篇 |
2006年 | 18949篇 |
2005年 | 16486篇 |
2004年 | 15609篇 |
2003年 | 14082篇 |
2002年 | 14204篇 |
2001年 | 15636篇 |
2000年 | 11926篇 |
1999年 | 9145篇 |
1998年 | 8039篇 |
1997年 | 7722篇 |
1996年 | 7160篇 |
1995年 | 6321篇 |
1994年 | 6295篇 |
1993年 | 6178篇 |
1992年 | 6518篇 |
1991年 | 7049篇 |
1990年 | 6761篇 |
1989年 | 6696篇 |
1988年 | 6321篇 |
1987年 | 6501篇 |
1986年 | 6073篇 |
1985年 | 7391篇 |
1984年 | 7671篇 |
1983年 | 6468篇 |
1982年 | 6637篇 |
1981年 | 6212篇 |
1980年 | 6001篇 |
1979年 | 6624篇 |
1978年 | 6661篇 |
1977年 | 6806篇 |
1976年 | 6818篇 |
1975年 | 6383篇 |
1974年 | 6199篇 |
1973年 | 6383篇 |
1972年 | 4988篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
The features of anthracite oxidation as influenced by temperature and time were determined. Physicochemical and sorption characteristics of the resulting cation exchanger were studied. 相似文献
942.
943.
Benedict Ita P. Murugavel V. Ponnambalam A. R. Raju 《Journal of Chemical Sciences》2003,115(5-6):519-524
Fine powders of lanthanum iron oxide, LaFeO3, have been prepared by solid state reaction as well as sol-gel synthesis and nebulized spray pyrolysis. Structures, morphologies
and magnetic susceptibility measurements of these powders have been examined. The powders prepared by all the three low-temperature
routes contain nearly spherical particles with an average diameter of 40 nm. These samples show a lower Neel temperature than
the powder prepared by solid state reaction besides showing much lower magnetic susceptibility at low temperatures.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
944.
We consider a nonautonomous inclusion the upper and lower selectors of whose right-hand side are determined by functions with discontinuities of the first kind. We prove that this problem generates a family of multivalued semiprocesses for which there exists a global attractor compact in the phase space. 相似文献
945.
Mathematical Notes - 相似文献
946.
947.
948.
N. V. Baranova S. A. Bogdanova V. G. Bandorin A. V. Kostochko 《Russian Journal of Applied Chemistry》2005,78(10):1659-1661
Single crystals of nitramine fillers for special-purpose polymeric composites are characterized by the surface energy and its constituents and also by the acidity of their surface. 相似文献
949.
Efrosyni Themistou Amelia Kanari Costas S. Patrickios 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):5811-5823
A compact, cleavable acylal dimethacrylate cross‐linker, 1,1‐ethylenediol dimethacrylate (EDDMA), was synthesized from the anhydrous iron(III) chloride‐catalyzed reaction between methacrylic anhydride and acetaldehyde. The ability of EDDMA to act as cross‐linker was demonstrated by using it for the preparation of one neat cross‐linker network, four star polymers of methyl methacrylate (MMA), and four randomly cross‐linked MMA polymer networks using group transfer polymerization (GTP). For comparison, the corresponding polymer structures based on the commercially available ethylene glycol dimethacrylate (EGDMA) cross‐linker (isomer of EDDMA) were also prepared via GTP. The number of arms of the EDDMA‐based star polymers was lower than that of the corresponding EGDMA polymers, whereas the degrees of swelling in tetrahydrofuran of the EDDMA‐based MMA networks were higher than those of their EGDMA‐based counterparts. Although none of the EDDMA‐containing polymers could be cleanly hydrolyzed under basic or acidic conditions, they could be thermolyzed at 200 °C within 1 day giving lower molecular weight products. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5811–5823, 2007 相似文献
950.
The method of numerical integration of the classical equations of motion was used to study interaction of a model two-electron atom with ultrashort laser pulses. Mechanisms and specific features of the ionization process were analyzed in a broad range of laser-field parameters. 相似文献