全文获取类型
收费全文 | 6015篇 |
免费 | 154篇 |
国内免费 | 23篇 |
专业分类
化学 | 3644篇 |
晶体学 | 30篇 |
力学 | 284篇 |
数学 | 1005篇 |
物理学 | 1229篇 |
出版年
2023年 | 46篇 |
2022年 | 156篇 |
2021年 | 148篇 |
2020年 | 128篇 |
2019年 | 109篇 |
2018年 | 96篇 |
2017年 | 101篇 |
2016年 | 219篇 |
2015年 | 174篇 |
2014年 | 166篇 |
2013年 | 308篇 |
2012年 | 323篇 |
2011年 | 359篇 |
2010年 | 225篇 |
2009年 | 209篇 |
2008年 | 354篇 |
2007年 | 334篇 |
2006年 | 296篇 |
2005年 | 310篇 |
2004年 | 220篇 |
2003年 | 205篇 |
2002年 | 149篇 |
2001年 | 92篇 |
2000年 | 85篇 |
1999年 | 66篇 |
1998年 | 59篇 |
1997年 | 56篇 |
1996年 | 73篇 |
1995年 | 64篇 |
1994年 | 57篇 |
1993年 | 55篇 |
1992年 | 39篇 |
1991年 | 34篇 |
1990年 | 43篇 |
1989年 | 35篇 |
1988年 | 37篇 |
1987年 | 45篇 |
1986年 | 35篇 |
1985年 | 64篇 |
1984年 | 67篇 |
1983年 | 31篇 |
1982年 | 37篇 |
1981年 | 39篇 |
1980年 | 44篇 |
1979年 | 35篇 |
1978年 | 27篇 |
1977年 | 44篇 |
1976年 | 24篇 |
1974年 | 21篇 |
1973年 | 19篇 |
排序方式: 共有6192条查询结果,搜索用时 15 毫秒
21.
Francesco Catoni Roberto Cannata Paolo Zampetti 《Advances in Applied Clifford Algebras》2006,16(2):85-101
It is known that complex numbers can be associated with plane Euclidean geometry and their functions are successfully used
for studying extensions of Euclidean geometry, i.e., non-Euclidean geometries and surfaces differential geometry.
In this paper we begin to study the constant curvature spaces associated with the geometry generated by commutative elliptic-quaternions
and we show how the “mathematics” they generate allows us to introduce these spaces and obtain the geodesic equations without
developing a complete mathematical apparatus as the one developed for Riemannian geometry. 相似文献
22.
23.
Nicola Fusco Michele Gori Francesco Maggi 《NoDEA : Nonlinear Differential Equations and Applications》2006,13(4):425-433
An approximation theorem for families of weakly coercive convex functions by means of countably many smooth families of convex
functions is proved. As a consequence, the classical “three-fold” lower semicontinuity theorem for integral functionals of
the Calculus of Variations by James Serrin is unified in one single statement. 相似文献
24.
We have investigated the distribution of conformations and orientations for a simple internal rotor molecule, 2,2'-bithienyl dissolved in liquid crystal solvents, by re-analysing published proton dipolar coupling data with the maximum entropy internal order method (MEIO). We show that detailed, model independent, conformational information can be obtained when data of sufficiently high quality are available. We also propose a novel and convenient representation method for the orientational-conformational coupling. 相似文献
25.
26.
Massimo Camarda Antonino La Magna Francesco La Via 《Journal of computational physics》2007,227(2):1075-1093
A modified Kinetic Lattice Monte Carlo model has been developed to predict growth rate regimes and defect formation in the case of the homo-epitaxial growth of close packed crystalline structures. The model is an improvement over standard Monte Carlo algorithms, which usually retain fixed atom positions and bond partners indicative of perfect crystal lattices. Indeed, we extend the concepts of Monte Carlo growth simulations on super-lattices containing additional sites (defect sites) with respect to those of the reference material. This extension implies a reconsideration of the energetic mapping, which is extensively presented, and allows to describe a complex phenomenology that is out of accessibility of standard stochastic approaches. Results obtained using the Kawasaki and the Bond-Counting rules for the transition probability of the Monte Carlo event are discussed in details. These results demonstrate how the defect types (local or extended), the formation mechanisms and the defect generation regimes can be characterized using our approach. 相似文献
27.
We prove that, under the assumption of the Generalized Riemann Hypothesis, the exponent of the ideal class group of a CM-field
goes to infinity with its absolute discriminant. This gives a positive answer to a question raised by Louboutin and Okazaki
[4].
Received September 10, 2001; in revised form April 5, 2002 相似文献
28.
N. A. A. Rossi R. G. Jones S. J. Holder 《Journal of polymer science. Part A, Polymer chemistry》2003,41(1):30-40
ABA block copolymers of methyl methacrylate and methylphenylsilane were synthesized with a methodology based on atom transfer radical polymerization (ATRP). The reaction of samples of α,ω‐dihalopoly(methylphenylsilane) with 2‐hydroxyethyl‐2‐methyl‐2‐bromoproprionate gave suitable macroinitiators for the ATRP of methyl methacrylate. The latter procedure was carried out at 95 °C in a xylene solution with CuBr and 2,2‐bipyridine as the initiating system. The rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with 1H NMR and 13C NMR spectroscopy and size exclusion chromatography, and differential scanning calorimetry was used to obtain preliminary evidence of phase separation in the copolymer products. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 30–40, 2003 相似文献
29.
Michaël Lejeune Andrea Valsesia Martin Kormunda Pascal Colpo François Rossi 《Surface science》2005,583(1):L142
In this work, chemically and topographically nanopatterned surfaces were produced by a top-down processing approach for biosensing devices. The nanopatterning was the result of the combination of plasma polymerisation (pp) of biofunctional materials and colloidal lithography techniques. The morphological and chemical properties induced by the plasma deposition-etching treatment were characterised by optical method combining ellipsometry and Fourier Transform Infrared spectroscopy studies. This method supported by atomic force microscopy measurements, allowed the full optical characterization of each step of the top-down process. The optical characterization of the end-up nanopatterned samples demonstrated that the chosen process is able to produce well-defined nanostructured surfaces with controlled chemical and morphological properties. 相似文献
30.
Francesco Michelangeli 《Journal of fluorescence》1991,1(3):203-206
A simple fluorimetric method is presented for measuring calcium uptake and inositol 1,4,5-trisphosphate (InsP3)-induced calcium release in microsomes using Fluo-3. This method is used to investigate the amplitude of calcium release (quantal release) induced by InsP3 from rat cerebellum microsomes. 相似文献