全文获取类型
收费全文 | 4640篇 |
免费 | 138篇 |
国内免费 | 16篇 |
专业分类
化学 | 2925篇 |
晶体学 | 13篇 |
力学 | 242篇 |
数学 | 799篇 |
物理学 | 815篇 |
出版年
2023年 | 40篇 |
2022年 | 94篇 |
2021年 | 134篇 |
2020年 | 109篇 |
2019年 | 98篇 |
2018年 | 82篇 |
2017年 | 93篇 |
2016年 | 186篇 |
2015年 | 144篇 |
2014年 | 144篇 |
2013年 | 255篇 |
2012年 | 266篇 |
2011年 | 290篇 |
2010年 | 176篇 |
2009年 | 154篇 |
2008年 | 283篇 |
2007年 | 271篇 |
2006年 | 226篇 |
2005年 | 237篇 |
2004年 | 166篇 |
2003年 | 161篇 |
2002年 | 121篇 |
2001年 | 53篇 |
2000年 | 48篇 |
1999年 | 48篇 |
1998年 | 33篇 |
1997年 | 34篇 |
1996年 | 56篇 |
1995年 | 46篇 |
1994年 | 40篇 |
1993年 | 35篇 |
1992年 | 31篇 |
1991年 | 29篇 |
1990年 | 30篇 |
1989年 | 31篇 |
1988年 | 29篇 |
1987年 | 40篇 |
1986年 | 23篇 |
1985年 | 44篇 |
1984年 | 42篇 |
1983年 | 22篇 |
1982年 | 24篇 |
1981年 | 29篇 |
1980年 | 32篇 |
1979年 | 20篇 |
1978年 | 21篇 |
1977年 | 35篇 |
1975年 | 14篇 |
1974年 | 13篇 |
1858年 | 11篇 |
排序方式: 共有4794条查询结果,搜索用时 31 毫秒
11.
A new microwave dielectric method for studying photoinitiated chain radical polymerization processes
Carlo Carlini Francesco Ciardelli Pier Angelo Rolla Elpidio Tombari 《Journal of Polymer Science.Polymer Physics》1987,25(6):1253-1261
Measurements of both real and imaginary parts of the dielectric constant at a fixed microwave frequency have been performed on n-butyl acrylate/poly(n-butyl acrylate) mixtures. The dielectric constant of the mixtures has been compared with that of neat n-butyl acrylate during UV photoinitiated polymerization. The values of the imaginary part of the dielectric constant thus obtained have allowed determination of the instantaneous monomer concentration and verified the kinetic equation for the photoinitiated polymerization process. The limits of validity of the method as well as its capability of providing detailed kinetic information are also discussed. 相似文献
12.
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
13.
14.
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
15.
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
16.
17.
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
18.
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
19.
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
20.
Giancarlo Marconi Sandra Monti Francesco Manoli Stefano Ottani 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):279-282
The Induced Circular Dichroism of the complex formed by inclusion of Licochalcone-A (a powerful antimalarian of natural origin)
and β-cyclodextrin was measured and calculated. The association constant was determined by titration experiments of ICD and
fluorescence. The lowest energy conformations of the complex were obtained through docking procedures and their Circular Dichroism
was evaluated within the Tinoco framework. The geometry of the complex was found to be consistent with the main experimental
features. 相似文献