全文获取类型
收费全文 | 5180篇 |
免费 | 629篇 |
国内免费 | 509篇 |
专业分类
化学 | 399篇 |
晶体学 | 36篇 |
力学 | 594篇 |
综合类 | 67篇 |
数学 | 3557篇 |
物理学 | 1665篇 |
出版年
2024年 | 8篇 |
2023年 | 52篇 |
2022年 | 72篇 |
2021年 | 96篇 |
2020年 | 99篇 |
2019年 | 155篇 |
2018年 | 149篇 |
2017年 | 158篇 |
2016年 | 148篇 |
2015年 | 148篇 |
2014年 | 232篇 |
2013年 | 529篇 |
2012年 | 190篇 |
2011年 | 288篇 |
2010年 | 240篇 |
2009年 | 332篇 |
2008年 | 382篇 |
2007年 | 327篇 |
2006年 | 325篇 |
2005年 | 267篇 |
2004年 | 237篇 |
2003年 | 283篇 |
2002年 | 259篇 |
2001年 | 212篇 |
2000年 | 188篇 |
1999年 | 160篇 |
1998年 | 141篇 |
1997年 | 128篇 |
1996年 | 104篇 |
1995年 | 58篇 |
1994年 | 66篇 |
1993年 | 35篇 |
1992年 | 34篇 |
1991年 | 34篇 |
1990年 | 18篇 |
1989年 | 8篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 5篇 |
排序方式: 共有6318条查询结果,搜索用时 15 毫秒
31.
Aït Hmaïdouch L. Mançour Billah S. El Hadek M. 《Journal of Thermal Analysis and Calorimetry》2002,69(2):659-667
The solid—liquid equilibria of the ternary system H2O—Al(NO3)3—Mg(NO3)2 were studied at –30, –20, –10 and 0°C by using a synthetic method which allows to detemine all the characteristic points of isothermal sections. The stable solid phases which appear are respectively: ice, Al(NO3)3·9H2O, Mg(NO3)2·9H2O and Mg(NO3)2·6H2O. Neither double salts nor mixed crystals are observed in the temperature and composition field studied. Polytherm diagram layout show two invariant transformations correspond with an eutectic point and a peritectic point.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
32.
G. A. Watson 《Advances in Computational Mathematics》1994,2(4):393-405
The orthogonal Procrustes problem involves finding an orthogonal matrix which transforms one given matrix into another in
the least-squares sense, and thus it requires the minimization of the Frobenius matrix norm. We consider, the solution of
this problem for a family of orthogonally invariant norms which includes the Frobenius norm as a special case. 相似文献
33.
S.V. Astashkin F.A. Sukochev 《Journal of Mathematical Analysis and Applications》2007,336(2):1231-1258
We catalogue all Marcinkiewicz function and sequence spaces with the Banach-Saks property and present necessary and sufficient conditions for a wide subclass of spaces to possess the p-Banach-Saks property, 1<p<∞. We apply our results to several open problems. 相似文献
34.
35.
A ring R has right SIP (SSP) if the intersection (sum) of two direct summands of R is also a direct summand. We show that the right SIP (SSP) is the Morita invariant property. We also prove that the trivial extension of R by M has SIP if and only if R has SIP and (1 – e)Me = 0 for every idempotent e in R. Moreover, we give necessary and sufficient conditions for the generalized upper triangular matrix rings to have SIP. 相似文献
36.
37.
设x:M→S^n+1(n≥23)是n+1-维单位球中的无脐点超曲面,Moebius不变量G,Ф,A和B分别表示x的Moebius度量,Moebius形式,Blaschke形式和Moebius第二基本形式.本文证明了如果x的Moebius形式圣平行,并且A+λG+μB=0,其中λ,μ分别是定义在M上的光滑函数,那么Ф=0,由此及李海中、王长平(2003年)文献中的分类定理给出了眇州中具有平行的Moebius形式及满足A+λG+μB=0的超曲面的分类.此结果推广了他们及张廷枋(2003年)文献中的结果. 相似文献
38.
How can the basic compatibility of theory and observations be investigated for nonlinear processes without requiring stochastic characterizations for residual error terms? The present paper proposes a flexible least-cost approach. For each possible estimatex for the sequence of process states, letc D (x) andx M(x) denote the costs incurred for deviations away from the prior dynamic specifications and prior measurement specifications, respectively. Define the cost-efficiency frontier to be the greatest lower bound for the set of all possible cost pairs [c D (x),c M(x)], conditional on the given observations. State sequence estimatesx that attain the cost-efficiency frontier indicate the possible ways that the actual process could have developed over time in a manner minimally incompatible with the prior dynamic and measurement specifications. An algorithm is developed for the exact sequential updating of the cost-efficient state sequence estimates as the duration of the process increases and additional observations are obtained. 相似文献
39.
40.
M. Maamache S. Menouar L. Krache 《International Journal of Theoretical Physics》2006,45(11):2191-2198
By using the Lewis-Riesenfeld theory and algebraic method, we present an alternative approach to obtain the exact solution of time-dependent Hamiltonian systems involving quadratic, inverse quadratic and (1/x)p+p(1/x) terms. This solution is discussed and compared with that obtained by Choi, J. R. (2003). International Journal of Theoretical Physics
42, 853].
PACS: 03.65Ge; 03.65Fd; 03.65Bz 相似文献