全文获取类型
收费全文 | 4582篇 |
免费 | 74篇 |
国内免费 | 10篇 |
专业分类
化学 | 2939篇 |
晶体学 | 34篇 |
力学 | 95篇 |
综合类 | 1篇 |
数学 | 731篇 |
物理学 | 866篇 |
出版年
2018年 | 59篇 |
2017年 | 85篇 |
2016年 | 65篇 |
2015年 | 67篇 |
2014年 | 71篇 |
2013年 | 162篇 |
2012年 | 204篇 |
2011年 | 213篇 |
2010年 | 132篇 |
2009年 | 132篇 |
2008年 | 113篇 |
2007年 | 136篇 |
2006年 | 146篇 |
2005年 | 177篇 |
2004年 | 139篇 |
2003年 | 134篇 |
2002年 | 93篇 |
2001年 | 69篇 |
2000年 | 60篇 |
1999年 | 44篇 |
1998年 | 42篇 |
1997年 | 50篇 |
1996年 | 49篇 |
1995年 | 72篇 |
1994年 | 65篇 |
1993年 | 51篇 |
1992年 | 47篇 |
1991年 | 48篇 |
1990年 | 38篇 |
1989年 | 48篇 |
1988年 | 37篇 |
1987年 | 55篇 |
1986年 | 44篇 |
1985年 | 62篇 |
1984年 | 71篇 |
1983年 | 42篇 |
1982年 | 68篇 |
1981年 | 61篇 |
1980年 | 60篇 |
1979年 | 48篇 |
1978年 | 78篇 |
1977年 | 76篇 |
1976年 | 54篇 |
1975年 | 51篇 |
1974年 | 46篇 |
1973年 | 59篇 |
1972年 | 40篇 |
1971年 | 49篇 |
1970年 | 38篇 |
1966年 | 29篇 |
排序方式: 共有4666条查询结果,搜索用时 15 毫秒
161.
162.
163.
Previous studies of kinetic transport in the Lorentz gas have been limited to cases where the scatterers are distributed at random (e.g., at the points of a spatial Poisson process) or at the vertices of a Euclidean lattice. In the present paper we investigate quasicrystalline scatterer configurations, which are non-periodic, yet strongly correlated. A famous example is the vertex set of a Penrose tiling. Our main result proves the existence of a limit distribution for the free path length, which answers a question of Wennberg. The limit distribution is characterised by a certain random variable on the space of higher dimensional lattices, and is distinctly different from the exponential distribution observed for random scatterer configurations. The key ingredients in the proofs are equidistribution theorems on homogeneous spaces, which follow from Ratner’s measure classification. 相似文献
164.
165.
Elvira Welzig Harald Pichler Rudolf Krska Dietmar Knopp Reinhard Niessner 《International journal of environmental analytical chemistry》2013,93(3-4):279-288
Abstract The development of an indirect competitive enzyme immunoassay for the sulfonylurea herbicide metsulfuron-methyl (MSM) is described. In contrast to traditional antibody generation in mammals, this extremely sensitive method is based on chicken egg yolk antibodies (IgY). They were raised in laying hens using an MSM-derivative-BSA hapten as immunogen. With a 1:10000 dilution of the antibody solution and a coating antigen (MSM-derivative-KLH) concentration of 10 μg L?1 the IC50 value achieved for the target analyte was 0.4 μg L?1. The least detectable dose was established at 13 ng L?1. Cross-reactivity was tested with 5 structurally related compounds, where only sulfometuron showed a significant binding. The ELISA was tested with spiked tap and surface water samples. This paper, for the first time, demonstrates the production of high-affinity IgY antibodies for a herbicide compound. 相似文献
166.
167.
Richard Paout Jaroslav Maixner Jitka Holakovsk Michal Duek Petr Ka
er 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(12):m340-m343
Another new substance from the family of Pt‐based coordination complexes with potential use in cancer chemotherapy has been synthesized, crystallized and structurally characterized. In this compound {systematic name cis‐dibromido[(1R,2R)‐cyclohexane‐1,2‐diamine‐κ2N,N′]platinum(II)}, cis‐[PtBr2(C6H14N2)], there are two molecules with very similar conformations in the asymmetric unit. The component species interact by way of N—H...Br and C—H...Br hydrogen bonds to give two‐dimensional networks which lie parallel to the (100) plane. 相似文献
168.
Karl Pays Caroline Mabille Véronique Schmitt Fernando Leal-Calderon J´erôme Bibette 《Journal of Dispersion Science and Technology》2013,34(1-3):175-186
This paper aims to review the various degradation pathays of emulsions. Aging of emulsions may proceed through three distinct microscopic mechanisms: diffusion or permeation, dewetting, and coalescence, each one being associated with a very characteristic growth scenario. We show within this context how double emulsions are a unique tool to complete the basic understanding of emulsion metastability. 相似文献
169.
170.
Dipl.‐Chem. Alexander Zhdanko Dr. Markus Ströbele Prof. Dr. Martin E. Maier 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(46):14732-14744
Coordination chemistry of gold catalysts bearing eight different ligands [L=PPh3, JohnPhos (L2), Xphos (L3), DTBP, IMes, IPr, dppf, S‐tolBINAP (L8)] has been studied by NMR spectroscopy in solution at room temperature. Cationic or neutral mononuclear complexes LAuX (L=L2, L3, IMes, IPr; X=charged or neutral ligand) underwent simple ligand exchange without giving any higher coordinate complexes. For L2AuX the following ligand strength series was determined: MeOH?hex‐3‐yne <MeCN≈OTf??Me2S<2,6‐lutidine<4‐picoline<CF3CO2?≈DMAP<TMTU<PPh3<OH?≈Cl?. Some heteroligand complexes DTBPAuX exist in solution in equilibrium with the corresponding symmetrical species. Binuclear complexes dppf(AuOTf)2 and S‐tolBINAP(AuOTf)2 showed different behavior in exchange reactions with ligands depending on the ligand strength. Thus, PPh3 causes abstraction of one gold atom to give mononuclear complexes LLAuPPh3+ and (Ph3P)nAu+, but other N and S ligands give ordinary dicationic species LL(AuNu)22+. In reactions with different bases, LAu+ provided new oxonium ions whose chemistry was also studied: (DTBPAu)3O+, (L2Au)2OH+, (L2Au)3O+, (L3Au)2OH+, and (IMesAu)2OH+. Ultimately, formation of gold hydroxide LAuOH (L=L2, L3, IMes) was studied. Ligand‐ or base‐assisted interconversions between (L2Au)2OH+, (L2Au)3O+, and L2AuOH are described. Reactions of dppf(AuOTf)2 and S‐tolBINAP(AuOTf)2 with bases provided more interesting oxonium ions, whose molecular composition was found to be [dppf(Au)2]3O22+, L8(Au)2OH+, and [L8(Au)2]3O22+, but their exact structure was not established. Several reactions between different oxonium species were conducted to observe mixed heteroligand oxonium species. Reaction of L2AuNCMe+ with S2? was studied; several new complexes with sulfide are described. For many reversible reactions the corresponding equilibrium constants were determined. 相似文献