全文获取类型
收费全文 | 41239篇 |
免费 | 861篇 |
国内免费 | 202篇 |
专业分类
化学 | 23775篇 |
晶体学 | 267篇 |
力学 | 1287篇 |
综合类 | 9篇 |
数学 | 5759篇 |
物理学 | 11205篇 |
出版年
2022年 | 422篇 |
2021年 | 518篇 |
2020年 | 539篇 |
2019年 | 459篇 |
2018年 | 540篇 |
2017年 | 453篇 |
2016年 | 844篇 |
2015年 | 747篇 |
2014年 | 921篇 |
2013年 | 1596篇 |
2012年 | 1942篇 |
2011年 | 2263篇 |
2010年 | 1266篇 |
2009年 | 1172篇 |
2008年 | 1894篇 |
2007年 | 1950篇 |
2006年 | 1861篇 |
2005年 | 2263篇 |
2004年 | 2159篇 |
2003年 | 1610篇 |
2002年 | 1227篇 |
2001年 | 1025篇 |
2000年 | 960篇 |
1999年 | 572篇 |
1998年 | 493篇 |
1997年 | 498篇 |
1996年 | 630篇 |
1995年 | 544篇 |
1994年 | 524篇 |
1993年 | 591篇 |
1992年 | 552篇 |
1991年 | 477篇 |
1990年 | 394篇 |
1989年 | 386篇 |
1988年 | 371篇 |
1987年 | 366篇 |
1986年 | 325篇 |
1985年 | 452篇 |
1984年 | 422篇 |
1983年 | 347篇 |
1982年 | 384篇 |
1981年 | 359篇 |
1980年 | 349篇 |
1979年 | 348篇 |
1978年 | 358篇 |
1977年 | 274篇 |
1976年 | 295篇 |
1975年 | 228篇 |
1974年 | 259篇 |
1973年 | 238篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Robert de Levie 《The Chemical Educator》2002,7(3):132-135
Using contemporary accounts, we describe the scope of the Henderson approximation, and its relationship to the mass action law of Guldberg & Waage. The Henderson approximation, apparently written in logarithmic form by Hasselbalch, has the same form as the mass action law, but has a completely different meaning and a much more restricted range of applicability. The Guldberg-Waage law is the fundamental mass action relationship valid for all chemical equilibria, whereas the Henderson approximation is useful only within a limited range of a sufficiently concentrated two-component buffer mixture. 相似文献
62.
A Hodge structure V of weight k on which a CM field acts defines, under certain conditions, a Hodge structure of weight , its half twist. In this paper we consider hypersurfaces in projective space with a cyclic automorphism which defines an
action of a cyclotomic field on a Hodge substructure in the cohomology. We determine when the half twist exists and relate
it to the geometry and moduli of the hypersurfaces. We use our results to prove the existence of a Kuga-Satake correspondence
for certain cubic 4-folds.
Received: 25 August 2000; in final form: 8 January 2001 / Published online: 18 January 2002 相似文献
63.
A.F. Mesquita A.O. Porto G.M. de Lima J.M. Delgado F.S. Lameiras 《Solid State Communications》2005,136(3):133-137
Hexagonal and cubic cadmium selenide were prepared from a chemical route by using cadmium chloride and potassium selenium hydride obtained from reaction of selenium powder and potassium boron hydride. The product obtained was thermally treated under argon flux at 300, 500 and 600 °C for 2 h and characterized by X-ray photoelectron spectroscopy and X-ray diffraction. The X-ray diffraction data were refined by Rietveld method and the structural parameters were determined for the phases of each annealed samples. At 300 °C five phases were identified: Cubic and hexagonal cadmium selenides and the contaminants: Potassium chloride, boron oxide and cadmium boron oxide. At 500 and 600 °C only the hexagonal cadmium selenide phase was identified besides the other above mentioned contaminant. 相似文献
64.
65.
J. D. van der Plaats 《Fresenius' Journal of Analytical Chemistry》1887,26(1):275-276
Ohne Zusammenfassung 相似文献
66.
J.-C. Thomas L. Achouri J. Äystö R. Béraud B. Blank G. Canchel S. Czajkowski P. Dendooven A. Ensallem J. Giovinazzo N. Guillet J. Honkanen A. Jokinen A. Laird M. Lewitowicz C. Longour F. de Oliveira Santos K. Peräjärvi M. Stanoiu 《The European Physical Journal A - Hadrons and Nuclei》2004,21(3):419-435
67.
Quiver Hopf algebras 总被引:1,自引:0,他引:1
In this paper we study subHopfalgebras of graded Hopf algebra structures on a path coalgebra kQc. We prove that a Hopf structure on some subHopfquivers can be lifted to a Hopf structure on the whole Hopf quiver. If Q is a Schurian Hopf quiver, then we classified all simple-pointed subHopfalgebras of a graded Hopf structure on kQc. We also prove a dual Gabriel theorem for pointed Hopf algebras. 相似文献
68.
69.
YBa2Cu3O7-x (YBCO) bulk is one of the most important high temperature superconducting materials for magnetic levitation applications, because it has a high magnetic irreversibility field Hirr at liquid nitrogen temperature, and can grow into large grains. The levitation force of YBCO bulk is proportional to the critical current density (Jc) and grain radius (r)[1], so higher Jc and r are appreciated for YBCO bulks to achieve higher levitation force. Now single-domain YBCO bulks up to s… 相似文献
70.
Affine Arithmetic: Concepts and Applications 总被引:2,自引:0,他引:2
Affine arithmetic is a model for self-validated numerical computation that keeps track of first-order correlations between computed and input quantities. We explain the main concepts in affine arithmetic and how it handles the dependency problem in standard interval arithmetic. We also describe some of its applications. 相似文献