全文获取类型
收费全文 | 14834篇 |
免费 | 2951篇 |
国内免费 | 3128篇 |
专业分类
化学 | 10732篇 |
晶体学 | 313篇 |
力学 | 1043篇 |
综合类 | 268篇 |
数学 | 1825篇 |
物理学 | 6732篇 |
出版年
2024年 | 55篇 |
2023年 | 264篇 |
2022年 | 559篇 |
2021年 | 568篇 |
2020年 | 697篇 |
2019年 | 657篇 |
2018年 | 604篇 |
2017年 | 580篇 |
2016年 | 762篇 |
2015年 | 812篇 |
2014年 | 959篇 |
2013年 | 1194篇 |
2012年 | 1482篇 |
2011年 | 1471篇 |
2010年 | 1146篇 |
2009年 | 1166篇 |
2008年 | 1258篇 |
2007年 | 1083篇 |
2006年 | 977篇 |
2005年 | 788篇 |
2004年 | 601篇 |
2003年 | 471篇 |
2002年 | 466篇 |
2001年 | 399篇 |
2000年 | 344篇 |
1999年 | 273篇 |
1998年 | 167篇 |
1997年 | 149篇 |
1996年 | 150篇 |
1995年 | 112篇 |
1994年 | 117篇 |
1993年 | 89篇 |
1992年 | 91篇 |
1991年 | 67篇 |
1990年 | 67篇 |
1989年 | 50篇 |
1988年 | 36篇 |
1987年 | 24篇 |
1986年 | 26篇 |
1985年 | 33篇 |
1984年 | 24篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1966年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Introduction In the previous studies on the oxidation reaction,peroxydisulfate was widely used as an oxidizingagent.1-5 One of the advantages of this oxidant lies in itsstability in a wide range of pH values. The reaction be-tween Fe(CN)5L3- (L=N-aromatic heterocyclic li-gands) and S2O8 2- has been proved to proceed throughan outer-sphere electron transfer mechanism.5 For a re-action [(Eq. (1)] to be under an outer-sphere mechanismthe steps involved are the formation of a reactant … 相似文献
32.
A New Triterpene from the Orchid Pholidota yunnanensis 总被引:2,自引:0,他引:2
ZhiMingBI ZhengTaoWANG LuoShanXU 《中国化学快报》2004,15(10):1179-1181
A new triterpene, 25-methylenecyclopholidonyl p-hydroxy-trans-cinnamate, was isolated from a orchid Pholidota yunnanensis. The structure elucidation and ^1H, ^13C-NMR assignments were achieved by spectral and chemical method. 相似文献
33.
XiangBaoMENG HuiLI QingLI ZhongJunLI 《中国化学快报》2004,15(7):777-778
An unusual reductive ring-opening reaction of phthalimide with sodium hydride in anhydrous DMF was observed for the first time. The presumed mechanism was described in detail. 相似文献
34.
Ming Zhao WANG Guan Liang CAI Ling XIA Jun Jian YAO Hong Yan CHEN Zhao Xing MENG Bo Li LIUDepartment of Chemistry Beijing Normal University Beijing Chemical Defense Institute PLA Beijing 《中国化学快报》2004,15(4):495-497
The crystal structures of two potential tumor imaging agents and therapeutic agents -copper(Ⅱ) complexes with salicylidene-tyrosinato Schiff base and nitrogen-donor chelating Lewis base, [Cu(sal-tyr)(bipy)] 1 and [Cu(sal-tyr)(phen)]2CH3OH 2 are presented. Our work is helpful to get deep understanding of novel 64Cu tumor imaging agents and therapeutic agents. 相似文献
35.
36.
Let f be a smooth map between unit spheres of possibly different dimensions. We prove the global existence and convergence of the mean curvature flow of the graph of f under various conditions. A corollary is that any area‐decreasing map between unit spheres (of possibly different dimensions) is isotopic to a constant map. © 2004 Wiley Periodicals, Inc. 相似文献
37.
38.
39.
Tao Liu Zuxiong Xu Zhongtao Zhao Ruzhang Ma Tiandou Hu Yaning Xie Yinghuan Guo 《中国科学A辑(英文版)》1997,40(4):395-399
The role of magnetoelastic coupling effects in nanocrystalline ferromagnets is investigated by means of high-field magnetization and Doppler-broadening spectrum measurements. For the nanocrystalline Fe73 5Cu1Nb3Si13.5B9 alloy, the results show that the pinning effects resulting from the quasidislocation dipole intensely influence the movement of domain wall; by coupling with the magnetostriction the defects-induced stress fields determine the magnetic properties at the early stage of crystallization. In view of the effective anisotropy and magnetoelastic coupling energy the optimal annealing conditions of alloys are discussed. 相似文献
40.
孟良义 《中国科学B辑(英文版)》1993,(4)
According to the features of geophysics, experimental petrology, granite geology and geochemistry, the differentiations of ore-bearing granitic magmas are discussed. It is put forward that only the supergene differentiations of ore-bearing granitic magma might exist, instead of the hypogene one of the magma. Based on it, a supergene differentiation model for the ore-bearlng granitic magma is presented. 相似文献