全文获取类型
收费全文 | 278596篇 |
免费 | 4230篇 |
国内免费 | 1553篇 |
专业分类
化学 | 157924篇 |
晶体学 | 3488篇 |
力学 | 10197篇 |
综合类 | 62篇 |
数学 | 35043篇 |
物理学 | 77665篇 |
出版年
2020年 | 2485篇 |
2019年 | 2470篇 |
2018年 | 3102篇 |
2017年 | 3156篇 |
2016年 | 5028篇 |
2015年 | 3686篇 |
2014年 | 4928篇 |
2013年 | 11937篇 |
2012年 | 10233篇 |
2011年 | 12537篇 |
2010年 | 8341篇 |
2009年 | 7874篇 |
2008年 | 11630篇 |
2007年 | 11700篇 |
2006年 | 11091篇 |
2005年 | 10085篇 |
2004年 | 8965篇 |
2003年 | 7783篇 |
2002年 | 7675篇 |
2001年 | 7709篇 |
2000年 | 6005篇 |
1999年 | 4414篇 |
1998年 | 3726篇 |
1997年 | 3741篇 |
1996年 | 3807篇 |
1995年 | 3342篇 |
1994年 | 3491篇 |
1993年 | 3378篇 |
1992年 | 3529篇 |
1991年 | 3481篇 |
1990年 | 3274篇 |
1989年 | 3151篇 |
1988年 | 3072篇 |
1987年 | 2974篇 |
1986年 | 2985篇 |
1985年 | 4031篇 |
1984年 | 4091篇 |
1983年 | 3478篇 |
1982年 | 3741篇 |
1981年 | 3471篇 |
1980年 | 3260篇 |
1979年 | 3368篇 |
1978年 | 3625篇 |
1977年 | 3633篇 |
1976年 | 3567篇 |
1975年 | 3250篇 |
1974年 | 3356篇 |
1973年 | 3399篇 |
1972年 | 2543篇 |
1971年 | 2058篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
L. A. Khalfin 《Journal of Mathematical Sciences》1987,36(5):616-626
The article surveys the main results of the statistical approach to the solution of ill-posed problems of mathematical physics, in application to specific ill-posed inverse problems in geophysics.Invited paper presented at the International Seminar on Mathematical Foundations of the Interpretation of Geophysical Fields, Moscow, May–June 1972.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 79, pp. 67–81, 1978. 相似文献
32.
Alcindo A. Dos Santos Renan S. Ferrarini Jefferson L. Princival João V. Comasseto 《Tetrahedron letters》2006,47(50):8933-8935
A masked lithium homoenolate, generated by tellurium/lithium exchange, was reacted with epoxides. The lithium compound was also converted into other organometallics such as Grignard, and cuprates and the reactivity of those organometallics with epoxides was evaluated. The same building block was employed in the synthesis of (+/−)-frontalin. 相似文献
33.
J. Maul I. Strachnov S. Karpuk P. Bernhard A. Oelsner G. Schönhense G. Huber 《Applied Physics A: Materials Science & Processing》2006,82(1):43-47
We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out. PACS 52.38.Mf; 79.20.Ds; 65.40.De 相似文献
34.
Mark L. Agranovsky E. K. Narayanan 《Proceedings of the American Mathematical Society》2006,134(7):2117-2123
A test for a function to be a solution of an elliptic PDE is given in terms of extensions, as solutions, from the boundaries inside the domains belonging to an isotopic family. It generalizes a result of Ehrenpreis for spheres moved along a straight line.
35.
36.
Abstract Under a suitable ellipticity condition, we show that classical SG-pseudodifferential operators of nonnegative order possess
complex powers. We show that the powers are again classical and derive an explicit formula for all homogeneous components.
Keywords: Complex power, Weighted symbols, Noncompact manifolds 相似文献
37.
Peter Dräxler 《Journal of Pure and Applied Algebra》2002,169(1):33-42
We show that the cleaving functors introduced in [Bautista et al., Invent. Math. 81 (1985) 217] as a tool for proving infinite representation type of finite-dimensional algebras can also be used to establish controlled wildness. The main application is that an algebra is controlled wild if there is an indecomposable projective module with a Loewy factor having a homogeneous direct summand which is of length at least 3. As a second application we derive Han's covering criterion. 相似文献
38.
39.
A. L. Apanasenko A. V. Kuznichenko Yu. B. Govyadovskii V. G. Yakunin 《Journal of Applied Spectroscopy》1991,54(3):271-276
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 3, pp. 438–444, March, 1991. 相似文献
40.
Rainer Löwen 《Journal of Geometry》1989,36(1-2):110-116
We prove that a spread S over a locally compact nondlscrete field F defines a topological translation plane if and only if the spread is compact. For F=R, this is implicit in Breuning's thesis [Bre], cf. [B 2]. For the proof, we describe the point set of the projective translation plane as a quotient space of some projective space, with identifications taking place in one hyperplane. This is new even for F=R. 相似文献