全文获取类型
收费全文 | 1774篇 |
免费 | 65篇 |
国内免费 | 16篇 |
专业分类
化学 | 1181篇 |
晶体学 | 43篇 |
力学 | 47篇 |
数学 | 237篇 |
物理学 | 347篇 |
出版年
2023年 | 12篇 |
2022年 | 33篇 |
2021年 | 44篇 |
2020年 | 48篇 |
2019年 | 41篇 |
2018年 | 38篇 |
2017年 | 38篇 |
2016年 | 62篇 |
2015年 | 40篇 |
2014年 | 69篇 |
2013年 | 121篇 |
2012年 | 104篇 |
2011年 | 120篇 |
2010年 | 78篇 |
2009年 | 54篇 |
2008年 | 69篇 |
2007年 | 95篇 |
2006年 | 81篇 |
2005年 | 76篇 |
2004年 | 70篇 |
2003年 | 54篇 |
2002年 | 40篇 |
2001年 | 16篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 14篇 |
1996年 | 15篇 |
1995年 | 10篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 17篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 9篇 |
1981年 | 15篇 |
1980年 | 27篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1977年 | 19篇 |
1976年 | 19篇 |
1975年 | 7篇 |
1974年 | 7篇 |
排序方式: 共有1855条查询结果,搜索用时 15 毫秒
41.
Journal of Theoretical Probability - In this work, we consider the stochastic generalized Burgers–Huxley equation perturbed by space–time white noise and discuss the global solvability... 相似文献
42.
43.
Mohan MM 《Physical review. B, Condensed matter》1993,48(17):12478-12482
44.
The microwave-assisted dry media technology was utilized for the synthesis of some novel derivatives in the Hantzsch—Biginelli reaction. In this eco-friendly approach, the usage of organic solvents and hazardous reagents resulting in corrossion of materials was minimized, giving high yields of products within a short reaction time. 相似文献
45.
Won Sick Woo Sam Sik Kang Otto Seligmann V. Mohan Chari Hildebert Wagner 《Tetrahedron letters》1980,21(44):4255-4258
From the seeds of Phytolacca americana two new lignans, Americanin B and D, have been isolated and their structures elucidated mainly by spectroscopic methods 相似文献
46.
On the mechanism of nanopore filling of SAPO-5 molecular sieve by nitrogen molecules 总被引:1,自引:0,他引:1
Boddenberg B Radha Rani V Grosse R 《Langmuir : the ACS journal of surfaces and colloids》2004,20(25):10962-10969
SAPO-5 molecular sieve was synthesized according to patent literature and characterized with X-ray diffraction, electron microscopy (SEM, TEM), and solid state magic angle spinning NMR spectroscopy. The material of particles in the micrometer region was found to consist of ca. 20 nm microcrystallites packed in mostly parallel orientation to ca. 200 nm sized agglomerates. The nitrogen adsorption isotherm was measured at 77.6 K over ca. 7 decades of pressure up to pore saturation. The course of the isotherm is interpreted to consist of filling of the nanopores (diameter, 0.73 nm) up to 2N(2)/unit cell, subsequent multilayer adsorption on the outer surface of the agglomerates, and, finally, pore condensation in the interparticle adsorption space. The nanopore adsorption can be quantitatively reproduced with the statistical mechanical model of a quasi one-dimensional lattice gas taking intermolecular interactions into account. The evaluated energy parameters are of physically reasonable magnitude and agree with literature data. The multilayer part of the adsorption isotherm can be well represented by the Brunauer-Emmett-Teller model yielding a specific outer space area (63 m(2) g(-)(1)) which is consistent with estimated geometrical and pore size analysis data. 相似文献
47.
Venkatapuram Padmavathi Pinnu Thriveni Boggu Jagan Mohan Reddy Adivireddy Padmaja 《Journal of heterocyclic chemistry》2005,42(1):113-116
A new class of five membered heterocycles, thiadiazoles, triazoles and oxadiazoles were prepared from sulfonyl acetic acids via acid hydrazides. 相似文献
48.
T. L. Luke H. Mohan V. M. Manoj P. Manoj J. P. Mittal C. T. Aravindakumar 《Research on Chemical Intermediates》2003,29(4):379-391
Reactions of sulphate radical anion (SO·4
-) with 4,6-dihydroxy-2-methyl pyrimidine (DHMP), 2,4-dimethyl-6-hydroxy pyrimidine (DMHP), 6-methyl uracil (MU) and 5,6-dimethyl uracil (DMU) have been studied by pulse radiolysis at pH 3 and at pH 10. The transient intermediate spectra were compared with those from the reaction of hydroxyl radical (·OH). It is proposed that SO·4
- produces radical cations of these pyrimidines in the initial stage. These radical cations are short-lived except in the case of DMHP where a relatively longer lived radical cation is proposed to be formed. When there is a hydrogen atom attached to the N(1) or N(3) position, a deprotonation from these sites is highly favored. When there is no hydrogen attached to these sites, deprotonation from a substituted methyl group is favored. At acidic pH, deprotonation from nitrogen is observed for DHMP, MU and DMU. At basic pH, the radical cation reacts with OH- leading to the formation of OH adducts. 相似文献
49.
[reaction: see text] The 1,4-dipole derived from isoquinoline and DMAD has been shown to react readily with N-tosylimines resulting in the diastereoselective synthesis of 2H-pyrimido[2,1-a]isoquinoline derivatives. 相似文献
50.