全文获取类型
收费全文 | 329527篇 |
免费 | 5526篇 |
国内免费 | 3472篇 |
专业分类
化学 | 165073篇 |
晶体学 | 4712篇 |
力学 | 16486篇 |
综合类 | 247篇 |
数学 | 49731篇 |
物理学 | 102276篇 |
出版年
2021年 | 1974篇 |
2020年 | 2349篇 |
2019年 | 2499篇 |
2018年 | 11323篇 |
2017年 | 12196篇 |
2016年 | 8281篇 |
2015年 | 3955篇 |
2014年 | 4548篇 |
2013年 | 10219篇 |
2012年 | 13191篇 |
2011年 | 22647篇 |
2010年 | 14414篇 |
2009年 | 14192篇 |
2008年 | 19893篇 |
2007年 | 23113篇 |
2006年 | 9492篇 |
2005年 | 14804篇 |
2004年 | 10814篇 |
2003年 | 9955篇 |
2002年 | 8031篇 |
2001年 | 7313篇 |
2000年 | 5778篇 |
1999年 | 4072篇 |
1998年 | 3364篇 |
1997年 | 3278篇 |
1996年 | 3438篇 |
1995年 | 2949篇 |
1994年 | 2988篇 |
1993年 | 2829篇 |
1992年 | 3049篇 |
1991年 | 3099篇 |
1990年 | 2896篇 |
1989年 | 2790篇 |
1988年 | 2729篇 |
1987年 | 2640篇 |
1986年 | 2656篇 |
1985年 | 3450篇 |
1984年 | 3499篇 |
1983年 | 2928篇 |
1982年 | 3156篇 |
1981年 | 2924篇 |
1980年 | 2707篇 |
1979年 | 2901篇 |
1978年 | 3113篇 |
1977年 | 3063篇 |
1976年 | 3124篇 |
1975年 | 2833篇 |
1974年 | 2939篇 |
1973年 | 3030篇 |
1972年 | 2340篇 |
排序方式: 共有10000条查询结果,搜索用时 500 毫秒
91.
92.
93.
Natalia L. Calvo Sebastian O. SimonettiRubén M. Maggio Teodoro S. Kaufman 《Analytica chimica acta》2015
Exposure of cimetidine (CIM) to dry heat (160–180 °C) afforded, upon cooling, a glassy solid containing new and hitherto unknown products. The kinetics of this process was studied by a second order chemometrics-assisted multi-spectroscopic approach. Proton and carbon-13 nuclear magnetic resonance (NMR), as well as ultraviolet and infrared spectroscopic data were jointly used, whereas multivariate curve resolution with alternating least squares (MCR-ALS) was employed as the chemometrics method to extract process information. It was established that drug degradation follows a first order kinetics. 相似文献
94.
95.
ABSTRACT A new density functional for the study of associating inhomogeneous fluids based on Wertheim's first-order thermodynamic perturbation theory is presented and compared to the most currently used associating density functionals. This functional is developed using the weighted density approximation in the range of association of hard spheres. We implement this functional within the framework of classical density functional theory together with modified fundamental measure theory to account for volume exclusion of hard spheres. This approach is tested against molecular simulations from literature of pure associating hard spheres and mixtures of non-associationg and associating hard spheres with different number of bonding sites close to a hard uniform wall. Furthermore, we compare and review our results with the performance of associating functionals from literature, one based on fundamental measure theory and the inhomogeneous version of Wertheim's perturbation theory. Results obtained with classical DFT and the three functionals show excellent agreement with molecular simulations in systems with one hard wall. For the cases of small pores where only one or two layers of fluid are allowed discrepancies between results with classical DFT and molecular simulations were found. 相似文献
96.
Cuixia Cui Yong Gao Dr. Jun Li Chao Yang Meng Liu Prof. Dr. Huile Jin Prof. Dr. Zhenhai Xia Prof. Dr. Liming Dai Prof. Dr. Yong Lei Prof. Dr. Jichang Wang Prof. Dr. Shun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):8002-8007
Although tremendous efforts have been devoted to understanding the origin of boosted charge storage on heteroatom-doped carbons, none of the present studies has shown a whole landscape. Herein, by both experimental evidence and theoretical simulation, it is demonstrated that heteroatom doping not only results in a broadened operating voltage, but also successfully promotes the specific capacitance in aqueous supercapacitors. In particular, the electrolyte cations adsorbed on heteroatom-doped carbon can effectively inhibit hydrogen evolution reaction, a key step of water decomposition during the charging process, which broadens the voltage window of aqueous electrolytes even beyond the thermodynamic limit of water (1.23 V). Furthermore, the reduced adsorption energy of heteroatom-doped carbon consequently leads to more stored cations on the heteroatom-doped carbon surface, thus yielding a boosted charge storage performance. 相似文献
97.
98.
99.
100.