全文获取类型
收费全文 | 128639篇 |
免费 | 170篇 |
国内免费 | 111篇 |
专业分类
化学 | 47471篇 |
晶体学 | 2002篇 |
力学 | 8117篇 |
综合类 | 7篇 |
数学 | 27400篇 |
物理学 | 43923篇 |
出版年
2018年 | 9833篇 |
2017年 | 10801篇 |
2016年 | 4696篇 |
2015年 | 1131篇 |
2014年 | 401篇 |
2013年 | 976篇 |
2012年 | 5321篇 |
2011年 | 14353篇 |
2010年 | 8318篇 |
2009年 | 8447篇 |
2008年 | 12301篇 |
2007年 | 16233篇 |
2006年 | 853篇 |
2005年 | 8132篇 |
2004年 | 4314篇 |
2003年 | 4238篇 |
2002年 | 2031篇 |
2001年 | 869篇 |
2000年 | 853篇 |
1999年 | 477篇 |
1998年 | 401篇 |
1997年 | 352篇 |
1996年 | 498篇 |
1995年 | 491篇 |
1994年 | 445篇 |
1993年 | 406篇 |
1992年 | 422篇 |
1991年 | 470篇 |
1990年 | 442篇 |
1989年 | 455篇 |
1988年 | 434篇 |
1987年 | 429篇 |
1986年 | 412篇 |
1985年 | 506篇 |
1984年 | 538篇 |
1983年 | 419篇 |
1982年 | 423篇 |
1981年 | 449篇 |
1980年 | 423篇 |
1979年 | 452篇 |
1978年 | 458篇 |
1977年 | 348篇 |
1976年 | 403篇 |
1975年 | 347篇 |
1974年 | 336篇 |
1973年 | 396篇 |
1969年 | 237篇 |
1968年 | 293篇 |
1967年 | 376篇 |
1966年 | 336篇 |
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
991.
H. P. Gunnlaugsson K. Bharuth-Ram M. Dietrich M. Fanciulli H. O. U. Fynbo G. Weyer 《Hyperfine Interactions》2006,169(1-3):1315-1318
We report on the detection of Fe i –B pairs in heavily B doped silicon using 57Fe emission Mössbauer spectroscopy following implantation of radioactive 57Mn+ parent ions (T 1/2?=?1.5 min) at elevated temperatures >?850 K. The Fe i –B pairs are formed upon the dissociation of Fe i –V pairs during the lifetime of the Mössbauer state (T 1/2?=?100 ns). The resulting free interstitial Fei diffuses over sufficiently large distances during the lifetime of the Mössbauer state to encounter a substitutional B impurity atom, forming Fe i –B pairs, which are stable up to ~1,050 K on that time scale. 相似文献
992.
Yu. A. Dobrovolsky P. Jannasch B. Lafitte N. M. Belomoina A. L. Rusanov D. Yu. Likhachev 《Russian Journal of Electrochemistry》2007,43(5):489-501
The 2000–2006 achievements in the field of synthesis, property examination, and application of proton-exchange membranes are reviewed on the basis of more than 120 papers. 相似文献
993.
Denis V. Osin 《Archiv der Mathematik》2007,88(5):403-412
The aim of this paper is to show that free Burnside groups of sufficiently large odd exponent are non-amenable in a certain
strong sense. More precisely their left regular representations are isolated from the trivial representation uniformly on
finite generating sets. It follows that free Burnside groups are of uniform exponential growth. This answers a question of
de la Harpe.
This work has been partially supported by the NSF grant DMS-0605093 and by the RFBR Grant # 05-01-00892.
Received: 25 April 2006 相似文献
994.
C. Uranga C. Connell G.M. Borstad L.R. Zink M. Jackson 《Applied physics. B, Lasers and optics》2007,88(4):503-505
A three-laser heterodyne system was used to measure the frequencies of twelve previously observed far-infrared laser emissions
from the partially deuterated methanol isotopologues 13CD3OH and CHD2OH. Two laser emissions, a 53.773 μm line from 13CD3OH and a 74.939 μm line from CHD2OH, have also been discovered and frequency measured. The CO2 pump laser offset frequency was measured with respect to its center frequency for twenty-four FIR laser emissions from CH3OH, 13CD3OH and CHD2OH.
PACS 07.57.Hm; 42.55.Lt; 42.62.Eh 相似文献
995.
Michael J. Puls 《Archiv der Mathematik》2007,88(6):500-506
Let p be a real number greater than one. In this paper we study the vanishing and nonvanishing of the first L
p
-cohomology space of some groups that have one end. We also make a connection between the first L
p
-cohomolgy space and the Floyd boundary of the Cayley graph of a group. We apply the result about Floyd boundaries to show
that there exists a real number p such that the first L
p
-cohomology space of a nonelementary hyperbolic group does not vanish.
Received: 4 August 2006 Revised: 2 November 2006 相似文献
996.
997.
We give some sufficient conditions for proper lower semicontinuous functions on metric spaces to have error bounds (with exponents).
For a proper convex function f on a normed space X the existence of a local error bound implies that of a global error bound. If in addition X is a Banach space, then error bounds can be characterized by the subdifferential of f. In a reflexive Banach space X, we further obtain several sufficient and necessary conditions for the existence of error bounds in terms of the lower Dini
derivative of f.
Received: April 27, 2001 / Accepted: November 6, 2001?Published online April 12, 2002 相似文献
998.
O. S. Kushnir A. A. Bevz O. G. Vlokh L. F. Lutsiv-Shumskii 《Optics and Spectroscopy》2002,93(6):930-933
On the basis of a complex null-polarimetric method, the natural birefringence and the rotation of the optical indicatrix in crystals of deuterated triglycinesulfate are measured in the temperature range of 300–340 K. The temperature-dependent behavior of the optical parameters is shown to be close to that observed previously in triglycinesulfate crystals. Changes in them upon the ferroelectric phase transition can be accounted for by the spontaneous quadratic electro-optic effect, with the values of the electro-optic coefficients being larger by a factor of 1.4 than in triglycinesulfate crystals. 相似文献
999.
1000.
In a recent paper [17] we proposed a stochastic algorithm which generates optimal probabilities for the decompression of
an image represented by the fixed point of an IFS system (SAOP). We show here that such an algorithm is in fact a non trivial
example of Generalized Random System with Complete Connections. We also exhibit a generalization which could represent the
solution to the inverse problem for an image with grey levels, if a fixed set of contraction maps is available.
Received: 1 July 2002 相似文献