全文获取类型
收费全文 | 2117篇 |
免费 | 39篇 |
国内免费 | 7篇 |
专业分类
化学 | 1318篇 |
晶体学 | 18篇 |
力学 | 53篇 |
数学 | 259篇 |
物理学 | 515篇 |
出版年
2023年 | 9篇 |
2022年 | 28篇 |
2021年 | 29篇 |
2020年 | 34篇 |
2019年 | 23篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 54篇 |
2015年 | 55篇 |
2014年 | 50篇 |
2013年 | 111篇 |
2012年 | 103篇 |
2011年 | 114篇 |
2010年 | 79篇 |
2009年 | 81篇 |
2008年 | 119篇 |
2007年 | 99篇 |
2006年 | 111篇 |
2005年 | 109篇 |
2004年 | 92篇 |
2003年 | 77篇 |
2002年 | 64篇 |
2001年 | 49篇 |
2000年 | 46篇 |
1999年 | 32篇 |
1998年 | 30篇 |
1997年 | 31篇 |
1996年 | 31篇 |
1995年 | 24篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1990年 | 20篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 29篇 |
1984年 | 36篇 |
1983年 | 16篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 19篇 |
1979年 | 18篇 |
1978年 | 14篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 15篇 |
1972年 | 9篇 |
排序方式: 共有2163条查询结果,搜索用时 15 毫秒
1.
2.
We study a class of nonlinear regression models for scalar or vectorial response when the explanatory variable is a function. We introduce a consistent estimator of the parameters of models in this class when functions are evaluated at randomly chosen observation points. To cite this article: F. Rossi, B. Conan-Guez, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
3.
Ornella Azzolina Simona Collina Daniela Rossi Enrica Lanza 《Tetrahedron letters》2004,45(7):1355-1357
The diastereoselective synthesis of naphthyl amino alcohols via nucleophilic addition to racemic 1-dimethylamino-2-methylpentan-3-one was studied. The use of the appropriate experimental conditions allowed the synthesis of both diastereoisomers. The relative configurations were established via NOESY experiments. 相似文献
4.
For ϕ a δ-subharmonic function, sharp results are obtained that connectA(r, ϕ), B(r, ϕ) andT(r, ϕ), whereA(r, ϕ)=inf|z|=r
ϕ(z),B(r, ϕ)=sup|z|=r
ϕ(z), andT(r, ϕ) is the Nevanlinna characteristics. 相似文献
5.
Hans‐Peter Brack Denise Ruegg Heinrich Bührer Michal Slaski Selmiye Alkan Günther G. Scherer 《Journal of Polymer Science.Polymer Physics》2004,42(13):2612-2624
The influence of irradiation and grafting on the crystallinity of three base polymers has been investigated with differential scanning calorimetry. Grafting has the largest effect on the base polymer crystallinity and results in a reduction of the crystallinity. The thermal degradation of the base polymers and grafted films has been investigated with thermogravimetric analysis. The extent of the fluorination of the base polymer, the irradiation method, and the graft level all influence the thermal degradation and its activation energy. It is proposed that the variation of the chain lengths of the grafted polystyrene chains is actually a primary underlying factor responsible for the influence of these various parameters on the degradation process. The first results of a comparative thermal analysis of some fuel‐cell membranes are also presented, and the promise and shortcomings of this method are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2612–2624, 2004 相似文献
6.
Jun Fujii Giancarlo Panaccione Giorgio Rossi Giancarlo Trimarchi 《Surface science》2006,600(18):3884-3887
Bulk carbon impurities segregate at the Fe(1 0 0) surface and, upon thermal annealing, can form metastable surface phases with local and long range order and peculiar electronic properties. We present a surface science study of C-segregated Fe(1 0 0) with scanning tunneling microscopy, angle resolved photoemission, and ab initio calculations of the surface structure and electron states. In particular the c(3√2 × √2) structure, observed for 0.67 atomic layers of C segregated at the iron surface, is found to be due to self-organized carbon stripes made of zig-zag chains. The strong hybridization between C and Fe was observed in ARPES spectra. 相似文献
7.
The N-carboethoxy precursor to (±)-tecomanine has been prepared in 11 steps from 2-methyl-1-buten-3-yne. The key step, Pauson-Khand cyclization of a methylated 5-aza-6-nonen-1-yne succeeds, but only in low yield, a consequence of the dialkyl substitution about the azaenyne framework. Nevertheless, the overall sequence to that point is one of the more efficient to be described. 相似文献
8.
Particle filters are presently among the most powerful tools for filtering discrete time non linear systems. However the presence of unknown parameters in the system equations makes their use more complex and can even impair their convergence properties. This Note shows how an on-line consistent estimation of these parameters can be obtained simultaneously to that of the state variables to be filtered. This approach relies upon a kernel-based non parametric estimation of conditional probability densities from successive Monte Carlo generations of system particles. To cite this article: V. Rossi, J.-P. Vila, C. R. Acad. Sci. Paris, Ser. I 340 (2005). 相似文献
9.
Giorgio AbbiatiAntonio Arcadi Egle BeccalliElisabetta Rossi 《Tetrahedron letters》2003,44(28):5331-5334
Intramolecular cyclization of 2-acyl-1-propargyl-1H-indoles in the presence of ammonia provides an easy entry to pyrazino[1,2-a]indole nucleus. 相似文献
10.
G. Baldsiefen H. Hübel W. Korten U. J. van Severen J. A. Cizewski N. H. Medina D. R. Napoli C. Rossi Alvarez G. Lo Bianco S. Signorelli 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):337-338
High-spin states in196Pb have been populated using the reaction170Er(30Si,4n). The previously observed shears bands in this nucleus have been extended and some of their transitions have been reordered. They now form regular bands with band crossings. One of the bands splits into two pathways at high spin. 相似文献