全文获取类型
收费全文 | 8982篇 |
免费 | 1315篇 |
国内免费 | 1328篇 |
专业分类
化学 | 6510篇 |
晶体学 | 105篇 |
力学 | 749篇 |
综合类 | 101篇 |
数学 | 1181篇 |
物理学 | 2979篇 |
出版年
2024年 | 27篇 |
2023年 | 175篇 |
2022年 | 237篇 |
2021年 | 311篇 |
2020年 | 339篇 |
2019年 | 320篇 |
2018年 | 246篇 |
2017年 | 263篇 |
2016年 | 450篇 |
2015年 | 373篇 |
2014年 | 487篇 |
2013年 | 622篇 |
2012年 | 761篇 |
2011年 | 718篇 |
2010年 | 586篇 |
2009年 | 496篇 |
2008年 | 551篇 |
2007年 | 468篇 |
2006年 | 451篇 |
2005年 | 447篇 |
2004年 | 373篇 |
2003年 | 341篇 |
2002年 | 402篇 |
2001年 | 363篇 |
2000年 | 248篇 |
1999年 | 266篇 |
1998年 | 197篇 |
1997年 | 175篇 |
1996年 | 186篇 |
1995年 | 145篇 |
1994年 | 132篇 |
1993年 | 96篇 |
1992年 | 74篇 |
1991年 | 72篇 |
1990年 | 45篇 |
1989年 | 27篇 |
1988年 | 35篇 |
1987年 | 19篇 |
1986年 | 29篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1957年 | 3篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Yuekun Lai Yicong Chen Yuxin Tang Dangguo Gong Zhong Chen Changjian Lin 《Electrochemistry communications》2009,11(12):2268-2271
A facile electrophoretic deposition (EPD) process has been developed to prepare thin films consisting of titanate nanotubes (TNTs) that were synthesized by a hydrothermal approach. Such an EPD process offers easy control in the film thickness and the adhesion to the substrate was found to be strong. The chemical composition and structure of the products have been characterized by XRD, HRTEM, and FESEM. It was found that the functionalization of TNTs plays a key role on the electrolyte stability and the formation of a uniform TNT film with good adhesion. The as-prepared TNT films show exceptional superhydrophilic behavior with ultra-fast spreading, while it converts to superhydrophobicity yet with strong adhesion after 1H,1H,2H,2H-perfluorooctyl-triethoxysilane modification. This study provides an interesting method to prepare films with extremely high wettability contrast that are useful for producing different types of functional materials. 相似文献
992.
993.
In this article, based on Lyapunov–Krasovskii functional method and stochastic analysis theory, we obtain some new criteria ensuring mean square stability of trivial solution of a class of impulsive stochastic differential equations with delays. As an application, a class of stochastic impulsive neural network with delays has been discussed. One illustrative example has been provided to show the effectiveness of our results. 相似文献
994.
This article generalizes the formulas of Gauss-Ostrogradskii type for semibasic vector fields from Riemannian manifolds to real Finsler manifolds and obtains some formulas of Gauss-Ostrogradskii type for Finsler vector fields which are expressed in terms of the vertical and horizontal derivatives of the Cartan connection in real Finsler manifolds. 相似文献
995.
In this work,a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water.Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time.Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfact... 相似文献
996.
997.
Shujun Tan Zhigang Wu Wanxie Zhong 《力学学报》2009,41(6):961
讨论了基于Pad\'{e}逼近的矩阵指数精细积分方法中加权系数N
和展开项数q的自适应选择问题. 参数(N,q)的选择直接影响到矩阵指数计算的精度和效
率. 采用矩阵函数逼近理论,研究了参数N和q的增加对精度的影响程度,据此,提出了
参数(N,q)优化组合的递推自适应选择方法. 该方法可以根据矩阵本身的性态选择合适的参
数(N,q),而参数选择的计算量与矩阵指数的计算量相比几乎可以忽略,这对于增强矩阵指
数精细积分方法的适应性和提高计算效率是很有益处的. 算例验证了该方法的正确性和有效性. 相似文献
998.
S. Shanmuga Sundara Raj Hoong‐Kun Fun Zhong‐Lin Lu Wen Xiao Xiao‐Yang Gong Chang‐Ming Gen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1013-1014
The crystal structure of the title compound, C15H14N2O2·H2O, is in the keto tautomeric form and the configuration at the azomethine C=N double bond is E. The molecule is non‐planar, with a dihedral angle of 27.3 (1)° between the aromatic rings. The crystal structure is stabilized by extensive hydrogen bonding involving the water molecule and hydrazone moiety. 相似文献
999.
Zhi NA Bei JIANG Hui YANG Zhong Wen LIN Han Dong SUN* Laboratory of Phytochemistry Kunming Institute of Botany Chinese Academy of Sciences Kunming Chemistry Deparment of the College of Life Science Chemistry Yunnan University K 《中国化学快报》2001,(8)
Isodon enanderianus (Hand. -Mazz.) H. W. Li, has been used in folk medicine as anti-inflammatory and detoxified agent1. The Isodon genus is known to be rich in ent-kaurane diterpenoids, a series of new ent-kaurane diterpenoids have been isolated from the dried leaves of I. enanderianus2-4. In order to find more biologically active substances, we have carefully investigated the chemical constituents of I. enanderianus collected in Shiping county of Yunnan province, and as a result, enanderi… 相似文献
1000.