全文获取类型
收费全文 | 14464篇 |
免费 | 2622篇 |
国内免费 | 2706篇 |
专业分类
化学 | 11000篇 |
晶体学 | 50篇 |
力学 | 225篇 |
综合类 | 126篇 |
数学 | 4957篇 |
物理学 | 3434篇 |
出版年
2024年 | 53篇 |
2023年 | 211篇 |
2022年 | 406篇 |
2021年 | 495篇 |
2020年 | 628篇 |
2019年 | 644篇 |
2018年 | 484篇 |
2017年 | 568篇 |
2016年 | 904篇 |
2015年 | 877篇 |
2014年 | 992篇 |
2013年 | 1386篇 |
2012年 | 1098篇 |
2011年 | 1095篇 |
2010年 | 927篇 |
2009年 | 1100篇 |
2008年 | 1076篇 |
2007年 | 1136篇 |
2006年 | 1012篇 |
2005年 | 801篇 |
2004年 | 645篇 |
2003年 | 603篇 |
2002年 | 401篇 |
2001年 | 343篇 |
2000年 | 354篇 |
1999年 | 245篇 |
1998年 | 230篇 |
1997年 | 234篇 |
1996年 | 121篇 |
1995年 | 105篇 |
1994年 | 94篇 |
1993年 | 70篇 |
1992年 | 54篇 |
1991年 | 46篇 |
1990年 | 42篇 |
1989年 | 31篇 |
1988年 | 32篇 |
1987年 | 28篇 |
1986年 | 17篇 |
1985年 | 29篇 |
1984年 | 24篇 |
1983年 | 9篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 14篇 |
1978年 | 22篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1974年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 270 毫秒
51.
J. T. Hoeft M. Polcik D. I. Sayago M. Kittel R. Terborg R. L. Toomes J. Robinson D. P. Woodruff M. Pascal G. Nisbet C. L. A. Lamont 《Surface science》2003,540(2-3):441-456
The local adsorption geometry of CO adsorbed in different states on Ni(1 0 0) and on Ni(1 0 0) precovered with atomic hydrogen has been determined by C 1s (and O 1s) scanned-energy mode photoelectron diffraction, using the photoelectron binding energy changes to characterise the different states. The results confirm previous spectroscopic assignments of local atop and bridge sites both with and without coadsorbed hydrogen. The measured Ni–C bondlengths for the Ni(1 0 0)/CO states show an increase of 0.16 ± 0.04 Å in going from atop to bridge sites, while comparison with similar results for Ni(1 1 1)/CO for threefold coordinated adsorption sites show a further lengthening of the bond by 0.05 ± 0.04 Å. These changes in the Ni–CO chemisorption bondlength with bond order (for approximately constant adsorption energy) are consistent with the standard Pauling rules. However, comparison of CO adsorbed in the atop geometry with and without coadsorbed hydrogen shows that the coadsorption increases the Ni–C bondlength by only 0.06 ± 0.04 Å, despite the decrease in adsorption energy of a factor of 2 or more. This result is also reproduced by density functional theory slab calculations. The results of both the experiments and the density functional theory calculations show that CO adsorption onto the Ni(1 0 0)/H surface is accompanied by significant structural modification; the low desorption energy may then be attributed to the energy cost of this restructuring rather than weak local bonding. 相似文献
52.
Gabriele Bonanno 《Journal of Global Optimization》1998,12(1):101-104
In this note we introduce a suitable class of functionals, including the class of integral functionals, and prove that any (strict) local minimum of a functional of this class, defined on a decomposable space, is a (strict) global minimum. So, the recent result obtained by Giner in [1] is specified and extended. 相似文献
53.
本文引入并研究一类新的广义集值强非线性拟变分不等式,讨论这类广义集值强非线性拟变分不等式解的存在性以及由算法所构造的迭代序列的收敛性.我们的结果改进和发展了Noor,Siddiqi和Ansari等人近期的一些主要结果. 相似文献
54.
本文通过使用化多时滞为单时滞的技巧,研究了一类广泛的非线性泛函微分方程解的振动性,所得结果包含和改进了Hunt,Yorke等多人的结果. 相似文献
55.
The purpose of this paper is to give the Reid ``Roundabout Theorem' for quadratic functionals with general boundary conditions.
In particular, we describe the so-called coupled point and regularity condition introduced in [16] in terms of Riccati equation
solutions.
Accepted 27 February 1996 相似文献
56.
HUYUDA MENGZHIQING 《高校应用数学学报(英文版)》1998,13(4):473-477
In this paper, the existence theorem of the cone-weak subdiflerential of set-valued mapping in locally convex topological vector space is proved. 相似文献
57.
Recently, Fishbum and Lavalle (1995) and Lefèvre and Utev (1996) have considered some stochastic order relations specific for arithmetic random variables. The present work is concerned with these orderings, together with two other classes of stochastic order relations closely related. First, attention is paid to characterizations and various properties of all these orderings. Then, sufficient conditions of crossing-type for the two new classes of orderings are derived and extrema among discrete random variables are deduced. This is applied in actuarial sciences to obtain new bounds for the classical single life premiums as well as for the probability of ruin in the compound binomial risk model. 相似文献
58.
本文提出了一类特殊的n人合作对策模型─—弱1—凸对策,研究了弱1—凸对策的解的性质,并证明弱1—凸对策的解满足所有常见的公理化特征. 相似文献
59.
Browder-Petryshyn 型的严格伪压缩映射的粘滞迭代逼近方法 总被引:1,自引:0,他引:1
主要研究Browder-Petryshyn型的严格伪压缩映射的粘滞迭代逼近过程,证明了Browder-Petryshyn型的严格伪压缩映射的不动点集F(T)是闭凸集.在q-一致光滑且一致凸的Banach空间中,对于严格伪压缩映射T,利用徐洪坤在2004年引进的粘滞迭代得到的序列弱收敛于T的某个不动点.同时证明了Hilbert空间中Browder-Petryshyn型的严格伪压缩映射的相应迭代序列强收敛到T的某个不动点,其结果推广与改进了徐洪坤2004年的相应结果. 相似文献
60.