全文获取类型
收费全文 | 23503篇 |
免费 | 4318篇 |
国内免费 | 3021篇 |
专业分类
化学 | 16996篇 |
晶体学 | 367篇 |
力学 | 1389篇 |
综合类 | 199篇 |
数学 | 2494篇 |
物理学 | 9397篇 |
出版年
2024年 | 59篇 |
2023年 | 494篇 |
2022年 | 762篇 |
2021年 | 910篇 |
2020年 | 1038篇 |
2019年 | 1044篇 |
2018年 | 893篇 |
2017年 | 874篇 |
2016年 | 1222篇 |
2015年 | 1209篇 |
2014年 | 1431篇 |
2013年 | 1847篇 |
2012年 | 2233篇 |
2011年 | 2115篇 |
2010年 | 1539篇 |
2009年 | 1451篇 |
2008年 | 1544篇 |
2007年 | 1386篇 |
2006年 | 1232篇 |
2005年 | 1111篇 |
2004年 | 816篇 |
2003年 | 656篇 |
2002年 | 636篇 |
2001年 | 498篇 |
2000年 | 423篇 |
1999年 | 495篇 |
1998年 | 373篇 |
1997年 | 378篇 |
1996年 | 363篇 |
1995年 | 321篇 |
1994年 | 245篇 |
1993年 | 221篇 |
1992年 | 167篇 |
1991年 | 148篇 |
1990年 | 167篇 |
1989年 | 120篇 |
1988年 | 78篇 |
1987年 | 56篇 |
1986年 | 62篇 |
1985年 | 66篇 |
1984年 | 32篇 |
1983年 | 35篇 |
1982年 | 32篇 |
1981年 | 19篇 |
1980年 | 14篇 |
1977年 | 3篇 |
1942年 | 2篇 |
1936年 | 2篇 |
1930年 | 2篇 |
1916年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Let X be a metric space, B the σ-algebra of Borel subsets of X, and μ a probability measure on (X,B). In this note, for a measure-preserving map T (respectively a measure-preserving semi-flow φ) on (X,B,μ), we prove that if suppμ=X, and T (respectively φ) is weak-mixing, then T (respectively φ) has sensitive dependence. 相似文献
92.
Bing-sheng He Zhen-hua Yang Xiao-ming Yuan 《Journal of Mathematical Analysis and Applications》2004,300(2):139-374
Proximal point algorithms (PPA) are attractive methods for monotone variational inequalities. The approximate versions of PPA are more applicable in practice. A modified approximate proximal point algorithm (APPA) presented by Solodov and Svaiter [Math. Programming, Ser. B 88 (2000) 371–389] relaxes the inexactness criterion significantly. This paper presents an extended version of Solodov–Svaiter's APPA. Building the direction from current iterate to the new iterate obtained by Solodov–Svaiter's APPA, the proposed method improves the profit at each iteration by choosing the optimal step length along this direction. In addition, the inexactness restriction is relaxed further. Numerical example indicates the improvement of the proposed method. 相似文献
93.
Zhimin He 《Journal of Mathematical Analysis and Applications》2004,296(1):97-109
In this paper, by means of a new twin fixed-point theorem in a cone, the existence of at least two positive solutions of m-point boundary value problem for second order dynamic equations on time scales is considered. 相似文献
94.
95.
96.
Qingfa Wang Li Wang Yaquan Wang Fei He Zhenhua Li Zhentao Mi 《Reaction Kinetics and Catalysis Letters》2004,81(2):297-304
Deactivated palladium catalysts in the hydrogenation of anthraquinione were regenerated with ethanol, nitric acid, hydrogen
peroxide, boiling water and steam, respectively. The deactivated and regenerated catalysts were characterized by XPS, ICP,
TG, FTIR, TPD, XRD, etc., and studied in the hydrogenation of anthraquinone. The results showed that the main cause of catalyst deactivation is the
coverage of the active component by deposits. The treatments by hydrogen peroxide and boiling water can effectively regenerate
the deactivated catalysts.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
97.
Shui Cao ZHENG Huo Nan LIN Di He HU 《数学学报(英文版)》2005,21(5):1137-1148
In this paper, we investigate the Hausdorff measure for level sets of N-parameter Rd-valued stable processes, and develop a means of seeking the exact Hausdorff measure function for level sets of N-parameter Rd-valued stable processes. We show that the exact Hausdorff measure function of level sets of N-parameter Rd-valued symmetric stable processes of index α is Ф(r) = r^N-d/α (log log l/r)d/α when Nα 〉 d. In addition, we obtain a sharp lower bound for the Hausdorff measure of level sets of general (N, d, α) strictly stable processes. 相似文献
98.
99.
利用一维拉格朗日流体动力学程序Med103详细研究了产生类镍Ag,Cd,In,Sn, Sb离子和类氖Fe,Co,Ni,Cu,Zn离子的等离子体状态.通过对电子温度、离子丰度、离子数密度等状态参量的分析比较,得到了这两类等离子体状态之间的对应关系.即类镍银的等离子体状态与类氖铁 的相近,类镍镉的与类氖钴的相近,依次类推.利用这一对应关系可以方便地由类氖机理x射线激光的等离子体状态来对相应元素的类镍x射线激光的等离子体状态进行判断.
关键词:
类氖
类镍
等离子体状态
x射线激光 相似文献
100.