全文获取类型
收费全文 | 181844篇 |
免费 | 22121篇 |
国内免费 | 11465篇 |
专业分类
化学 | 127880篇 |
晶体学 | 2279篇 |
力学 | 9160篇 |
综合类 | 688篇 |
数学 | 20069篇 |
物理学 | 55354篇 |
出版年
2023年 | 1755篇 |
2022年 | 3162篇 |
2021年 | 4064篇 |
2020年 | 5473篇 |
2019年 | 6574篇 |
2018年 | 5396篇 |
2017年 | 5076篇 |
2016年 | 8819篇 |
2015年 | 7808篇 |
2014年 | 9354篇 |
2013年 | 12281篇 |
2012年 | 12446篇 |
2011年 | 12131篇 |
2010年 | 10086篇 |
2009年 | 9915篇 |
2008年 | 9994篇 |
2007年 | 8827篇 |
2006年 | 7812篇 |
2005年 | 7163篇 |
2004年 | 6010篇 |
2003年 | 5243篇 |
2002年 | 5942篇 |
2001年 | 4839篇 |
2000年 | 4122篇 |
1999年 | 3030篇 |
1998年 | 2488篇 |
1997年 | 2218篇 |
1996年 | 2155篇 |
1995年 | 1902篇 |
1994年 | 1845篇 |
1993年 | 1665篇 |
1992年 | 1547篇 |
1991年 | 1572篇 |
1990年 | 1500篇 |
1989年 | 1296篇 |
1988年 | 1122篇 |
1987年 | 1102篇 |
1986年 | 1066篇 |
1985年 | 1087篇 |
1984年 | 1019篇 |
1983年 | 921篇 |
1982年 | 874篇 |
1979年 | 824篇 |
1978年 | 830篇 |
1977年 | 832篇 |
1976年 | 946篇 |
1975年 | 840篇 |
1974年 | 856篇 |
1973年 | 866篇 |
1972年 | 771篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment,
exotic nuclei were produced via fragmentation of 152Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected
into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and
electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution
frequencies. Masses for 18 nuclides (84Zr, 92Ru, 94Rh, 107,108,110Sb, 111,112,114I, 118Ba, 122,123La, 124Ce, 127Pr, 129Nd, 132Pm, 134Sm, 137Eu) have been determined for the first time. Masses for 111,112I and 113Xe have been obtained via known α-decay energies. The experiment and first results will be presented. 相似文献
993.
Jing Ping YANG Shi Hong CHENG Xiao Qian WANG 《数学学报(英文版)》2007,23(3):467-478
This paper investigates bivariate recursive equations on excess-of-loss reinsurance. For an insurance portfolio, under the assumptions that the individual claim severity distribution has bounded continuous density and the number of claims belongs to R1 (a, b) family, bivariate recursive equations for the joint distribution of the cedent's aggregate claims and the reinsurer's aggregate claims are obtained. 相似文献
994.
995.
In this paper, we study a micro‐macro model for polymeric fluid. The system involves coupling between the macroscopic momentum equation and a microscopic evolution equation describing the combined effects of the microscopic potential and thermofluctuation. We employ an energetic variation procedure to explore the relation between the macroscopic transport of the particles and the induced elastic stress due to the microscopic structure. For the initial data not far from the equilibrium, we prove the global existence and uniqueness of classical solutions to the system. © 2006 Wiley Periodicals, Inc. 相似文献
996.
997.
998.
Conclusions DS provide a convenient means of researching local atomic configurations in disordered systems. On the one hand, a DS is a strictly defined geometrical structure, while on the other hand the shapes of the simplexes directly reflect the atomic disposition.New characteristics T and O have been proposed for DS shape and allow one to distinguish the corresponding configurations reliably. It is evident that a close-packed system of spherical atoms contains considerable proportions of slightly distorted tetrahedral and octahedral configurations. In a disordered close packing of soft spheres, such configurations form distinct classes similar to those occurring in an FCC crystal.Institute of Chemical Kinetics and Combustion, Siberian Branch, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 28, No. 2, pp. 62–69, March–April, 1987. 相似文献
999.
本文利用85年5—6月间对乌鲁木齐市主要商业区及部分中、小商业区的实地调查资料,对乌市商业中心等级系统进行了定性和定量的分级分类,将全市商业中心划分为五个等级,八组商业中心,对已形成的商业中心分布现状进行了初步探讨,并对今后商业网点的合理布局提出了建议。 相似文献
1000.
This work reports a new synthetic approach for single‐phase TiO2 nanomaterials by solvothermal treatment of titanium tetrachloride in acetone at 80–110 °C. Small, uniform, and yet size‐tunable (5–10 nm) anatase titania nanocrystallites were obtained using a low concentration of TiCl4 in acetone (i.e., at molar ratios of TiCl4/acetone ≤ 1:15) in the temperature range of 80–110 °C, while rutile nanofibers were synthesized using a high concentration of TiCl4 (e.g., TiCl4/acetone = 1:10) at 110 °C. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献