全文获取类型
收费全文 | 795篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
化学 | 494篇 |
晶体学 | 2篇 |
力学 | 9篇 |
数学 | 98篇 |
物理学 | 222篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 25篇 |
2020年 | 22篇 |
2019年 | 17篇 |
2018年 | 23篇 |
2017年 | 24篇 |
2016年 | 24篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 63篇 |
2012年 | 58篇 |
2011年 | 59篇 |
2010年 | 27篇 |
2009年 | 32篇 |
2008年 | 38篇 |
2007年 | 36篇 |
2006年 | 40篇 |
2005年 | 39篇 |
2004年 | 34篇 |
2003年 | 32篇 |
2002年 | 23篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有825条查询结果,搜索用时 265 毫秒
1.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Minaeva Alexandra P. Goloveshkin Alexander S. Hansford Karl A. Egorov Mikhail P. 《Molecular diversity》2020,24(4):1327-1342
Molecular Diversity - A novel five-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Knoevenagel condensation–Michael addition–Mannich cascade... 相似文献
2.
The dispersion relation of magnetostatic waves tangentially magnetized to saturation ferrite film, with a “magnetic wall” condition (tangential component of microwave magnetic field is equal to zero) on one of the film surface and with a metal condition on the opposite surface is analyzed. The dispersion characteristics show that unidirectional magnetostatic waves appear in this structure: they can transfer energy in one direction only and fundamentally cannot transfer energy in the opposite direction. The dispersion-free propagation of magnetostatic waves also is possible in the structure in a wide frequency interval. 相似文献
3.
M. F. Bundule A. F. Mishnev V. K. Lusis D. Kh. Mutsenietse A. Z. Zandersons G. Ya. Dubur 《Chemistry of Heterocyclic Compounds》1991,27(9):995-998
The molecular crystal structure of 4-phenyl-3,5-diethoxycarbonyl-1,2,6-trimethyl-1,2-dihydropyridine has been investigated by x-ray structural analysis. The three-dimensional structural properties of the molecule have been compared against the large observed reactivity of the 3-ethoxycarbonyl group with respect to nucleophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1236–1239, September, 1991. 相似文献
4.
5.
An optimization problem of interactive inhomogenous flows (Steiner multicommodity network flow problem) is formulated. The problem's main characteristic is a fixed charge change when combining multicommodity communications. In this paper we propose a method for solving this problem which, in order to restrict the search on the feasible domain, reduces the original problem to a concave programming problem in the form: min {f(x)|xX} wheref:n is a concave function, andX
0
n
is a flow polytope defined by network transportation constraints. For practical large-scale problems arising from planning transportation networks on inhomogeneous surfaces defined by a digital model, a method of local optimization over a flow polytope vertex set is proposed, which is far more effective in comparison with the Gallo and Sodini method under polytope strong degeneracy conditions. 相似文献
6.
A simple direct enzyme immunoassay for semiquantitative detec tion of antibodies is suggested. It is based on the difference
in diffusion rates in a gel for a synthetic low-mol-wt antigen and of its complexes with antibodies to be detected. Sensitivity
and specificity of the devel oped assay are equal to an ELISA method. The assay has been tested with antibodies against HIV
protein gp41 in rabbit serum. Possible applications and limitations of the method are discussed. 相似文献
7.
Han J Goncharov V Kaledin LA Komissarov AV Heaven MC 《The Journal of chemical physics》2004,120(11):5155-5163
The electronic spectroscopy of UO(2) has been examined using multiphoton ionization with mass-selected detection of the UO(2) (+) ions. Supersonic jet cooling was used to reduce the spectral congestion. Twenty-two vibronic bands of neutral UO(2) were observed in the range from 17,400 to 32,000 cm(-1). These bands originated from the U(5fphi(u)7ssigma(g))O(2) X (3)Phi(2u) and (3)Phi(3u) states. The stronger band systems are attributed to metal-centered 7p<--7s transitions. Threshold ionization measurements were used to determine the ionization potentials of UO and UO(2). These were found to be higher than the values obtained previously from electron impact measurements but in agreement with the results of recent theoretical calculations. 相似文献
8.
Express detection of nonylphenol in water samples by fluorescence polarization immunoassay 总被引:6,自引:0,他引:6
Yakovleva JN Lobanova AY Shutaleva EA Kourkina MA Mart'ianov AA Zherdev AV Dzantiev BB Eremin SA 《Analytical and bioanalytical chemistry》2004,378(3):634-641
The development of express method for detection of endocrine-disrupting chemicals (EDC) such as alkylphenols is required for ecological monitoring. Several attempts have been made to produce antibodies against 4-nonylphenol (NP) in recent years. This work describes the production of new antibodies against NP and also summarizes the characterization of antibodies obtained earlier. Three approaches used to produce alkylphenol-specific antibodies are compared; these are based on: 1. omega-(4-hydroxyphenyl)nonanoic or omega-(4-hydroxyphenyl)heptanoic acid NP derivatives designed to mimic the linear NP isomer; 2. 4-aminophenol, which potentially mimics various substituted phenolic compounds with different side-chain structures at position 4 of the benzene ring; and 3. a mixture of branched NP isomers, conjugated to the carrier protein via a benzene ring by the Mannich reaction, and expected to be the closest mimic of NP structure by preserving its natural alkyl moiety.Fluorescence polarization immunoassays based on different combinations of antibody and labeled antigen for screening detection of NP were developed and structural aspects of assay sensitivity and specificity were investigated. The assays based on the antisera raised against omega-(4-hydroxyphenyl)nonanoic acid and NP conjugate via Mannich reaction are capable of express detection of NP with detection limit of 7 microg mL(-1 )and assay dynamic range of 18-300 microg mL(-1). 相似文献
9.
Nazarov Anatoly Sztrik János Kvach Anna Tóth Ádám 《Methodology and Computing in Applied Probability》2022,24(3):1503-1518
Methodology and Computing in Applied Probability - This paper deals with a retrial queuing system with a finite number of sources and collision of the customers, where the server is subject to... 相似文献
10.
Medrano F Calderón A Yatsimirsky AK 《Chemical communications (Cambridge, England)》2003,(15):1968-1970
Glycine and N,N-dimethylglycine stabilize La(III) hydroxide complexes of the type La2L2(OH)4 which possess phosphodiesterolytic activity close to that observed with most active tetravalent cations like Ce(IV). 相似文献