全文获取类型
收费全文 | 11986篇 |
免费 | 1355篇 |
国内免费 | 2010篇 |
专业分类
化学 | 7914篇 |
晶体学 | 540篇 |
力学 | 89篇 |
综合类 | 59篇 |
数学 | 4139篇 |
物理学 | 2610篇 |
出版年
2024年 | 11篇 |
2023年 | 167篇 |
2022年 | 194篇 |
2021年 | 248篇 |
2020年 | 354篇 |
2019年 | 437篇 |
2018年 | 363篇 |
2017年 | 443篇 |
2016年 | 429篇 |
2015年 | 400篇 |
2014年 | 513篇 |
2013年 | 948篇 |
2012年 | 597篇 |
2011年 | 876篇 |
2010年 | 679篇 |
2009年 | 854篇 |
2008年 | 865篇 |
2007年 | 858篇 |
2006年 | 710篇 |
2005年 | 579篇 |
2004年 | 586篇 |
2003年 | 499篇 |
2002年 | 575篇 |
2001年 | 392篇 |
2000年 | 381篇 |
1999年 | 390篇 |
1998年 | 300篇 |
1997年 | 229篇 |
1996年 | 196篇 |
1995年 | 205篇 |
1994年 | 165篇 |
1993年 | 120篇 |
1992年 | 141篇 |
1991年 | 84篇 |
1990年 | 70篇 |
1989年 | 46篇 |
1988年 | 43篇 |
1987年 | 34篇 |
1986年 | 41篇 |
1985年 | 31篇 |
1984年 | 31篇 |
1983年 | 23篇 |
1982年 | 33篇 |
1981年 | 33篇 |
1980年 | 25篇 |
1979年 | 33篇 |
1978年 | 35篇 |
1977年 | 27篇 |
1976年 | 23篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
Mihai Tib?r 《Topology》2003,42(3):629-639
We show that the complex link of a large class of space germs (X,x0) is characterized by its “simplicity”, among the Milnor fibres of functions with isolated singularity on X. This amounts to the minimality of the Milnor number, whenever this number is defined. Such a phenomenon has been first pointed out in case (X,x0) is an isolated hypersurface singularity, by Teissier (Cycles évanescents, sections planes et conditions de Whitney, in: Singularités à Cargèse 1972, Asterisque, Nos. 7 et 8, Soc. Math. France, Paris, 1973, pp. 285-362). 相似文献
132.
Aleksey Zinger 《Topology》2004,43(4):793-829
We give a formula computing the number of one-nodal rational curves that pass through an appropriate collection of constraints in a complex projective space. The formula involves intersections of tautological classes on moduli spaces of stable rational maps. We combine the methods and results from three different papers. 相似文献
133.
Dimitri Leemans 《Journal of Geometry》2004,79(1-2):146-155
We construct nine rank five incidence geometries that are firm and residually connected
and on which the Mathieu group M22 acts flag-transitively. The constructions use
mainly objects arising from the Steiner systemS(3, 6, 22).
One of these geometries was constructed by Meixner and Pasini in [10]. Three of them
are obtained from the geometry of Meixner and Pasini using doubling (see [8] or [12]) or similar
constructions. The remaining five are new and four of them have a star diagram. These
latter four geometries are constructed using special partitions of the 22 points of
the Steiner system S(3, 6, 22). 相似文献
134.
Igor V. Dolgachev 《Milan Journal of Mathematics》2004,72(1):163-187
We review the classical definition of the dual homogeneous form of arbitrary even degree which generalizes the well-known notion of the dual quadratic form. Following the ideas of S. Mukai we apply this construction to the study of the varieties parametrizing representations of a homogeneous polynomial as a sum of powers of linear forms.Research supported in part by NSF Grant DMS 0245203.Lecture held in the Seminario Matematico e Fisico on October 15, 2003Received: April, 2004 相似文献
135.
136.
Hydrogenation of naphthalene on noble-metal-containing mesoporous MCM-41 aluminosilicates 总被引:2,自引:0,他引:2
S. Albertazzi R. Ganzerla C. Gobbi M. Lenarda M. Mandreoli E. Salatelli P. Savini L. Storaro A. Vaccari 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):261-270
Aromatic saturation of oil fractions is a key process in the refining industry due to increasing demand for cleanest distillates with superior performances. In this study, the behavior of different catalysts containing 1 wt.% of noble-metal inside a mesoporous MCM-41 (Si:Al=20) framework was investigated in the hydrogenation of naphthalene, as preliminary step to investigate bimetallic catalysts. While at atmospheric pressure only Rh and Pd showed a low hydrogenation activity, in the tests performed at 6.0 MPa the catalytic activity grew, exhibiting the following order: Pt>RhPd>>>Ru≈Ir. However, all the catalysts required a large H2 excess, to avoid a decrease in hydrogenation and ring-opening activity, and gave rise to the best performance for a contact time of 6.8 s, favouring at lower values the partial hydrogenation to tetralin and at higher values cracking reactions. Finally, all the catalysts showed low thio-tolerance, with significant deactivation already feeding 100 ppm wt. of dibenzothiophene (DBT), with a partial reversibility only for the Pt-containing catalyst (CAT 3). 相似文献
137.
138.
In this paper cubature formulas based on bivariate C
1 local polynomial splines with a four directional mesh [4] are generated and studied. Some numerical results with comparison
with other methods are given. Moreover the method proposed is applied to the numerical evaluation of 2‐D singular integrals
defined in the Hadamard finite part sense. Computational features, convergence properties and error bounds are proved.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
139.
Mohamed Krir 《manuscripta mathematica》1998,96(1):9-16
Let R be a complete discrete valuation ring with mixed characteristic. Denote by K its field of fractions and by k its residue field. Let 0 →A
K
→B
K
→C
K
→ 0 be an exact sequence of abelian varieties over K and consider the corresponding complex of Nérons models 0 →A→B→C→ 0, over R. We assume that the identity component B
k
0 of the special fibre B
k
of B is a torus and we study the defect of exactmess at B in this last sequence.
Re?u: 4 décembre 1997/ Version revisée: 15 décembre 1997 相似文献
140.
This paper studies the pullback asymptotic behavior of solutions for a non-autonomous incompressible non-Newtonian fluid in two-dimensional (2D) bounded domains. We first prove the existence of pullback attractors AV in space V (has H2-regularity, see notation in Section 2) and AH in space H (has L2-regularity) for the cocycle corresponding to the solutions of the fluid. Then we verify the regularity of the pullback attractors by showing AV=AH, which implies the pullback asymptotic smoothing effect of the fluid in the sense that the solutions become eventually more regular than the initial data. 相似文献