全文获取类型
收费全文 | 588129篇 |
免费 | 7972篇 |
国内免费 | 2472篇 |
专业分类
化学 | 317259篇 |
晶体学 | 8665篇 |
力学 | 25698篇 |
综合类 | 72篇 |
数学 | 70726篇 |
物理学 | 176153篇 |
出版年
2021年 | 4787篇 |
2020年 | 5362篇 |
2019年 | 5821篇 |
2018年 | 7501篇 |
2017年 | 7422篇 |
2016年 | 11272篇 |
2015年 | 7205篇 |
2014年 | 10983篇 |
2013年 | 26541篇 |
2012年 | 20966篇 |
2011年 | 25586篇 |
2010年 | 18004篇 |
2009年 | 17807篇 |
2008年 | 23684篇 |
2007年 | 23646篇 |
2006年 | 21966篇 |
2005年 | 19726篇 |
2004年 | 18109篇 |
2003年 | 15929篇 |
2002年 | 15714篇 |
2001年 | 17586篇 |
2000年 | 13371篇 |
1999年 | 10276篇 |
1998年 | 8633篇 |
1997年 | 8391篇 |
1996年 | 8195篇 |
1995年 | 7314篇 |
1994年 | 7287篇 |
1993年 | 7060篇 |
1992年 | 7804篇 |
1991年 | 7858篇 |
1990年 | 7509篇 |
1989年 | 7272篇 |
1988年 | 7182篇 |
1987年 | 7053篇 |
1986年 | 6769篇 |
1985年 | 8897篇 |
1984年 | 9035篇 |
1983年 | 7334篇 |
1982年 | 7568篇 |
1981年 | 7365篇 |
1980年 | 6813篇 |
1979年 | 7353篇 |
1978年 | 7676篇 |
1977年 | 7598篇 |
1976年 | 7526篇 |
1975年 | 6990篇 |
1974年 | 7066篇 |
1973年 | 7043篇 |
1972年 | 5162篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Knyazev A. A. Karyakin M. E. Krupin A. S. Galyametdinov Yu. G. 《Russian Journal of General Chemistry》2015,85(12):2806-2812
Russian Journal of General Chemistry - Hybrid liquid crystal systems with different ratios of the components have been prepared on the basis of 5,5′-di(heptadecyl)-2,2′-bipyridine... 相似文献
62.
63.
Nano palladium supported on high‐surface‐area metal–organic framework MIL‐101: an efficient catalyst for Sonogashira coupling of aryl and heteroaryl bromides with alkynes
下载免费PDF全文
![点击此处可从《应用有机金属化学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Manne Annapurna T. Parsharamulu P. Vishnuvardhan Reddy M. Suresh Pravin R. Likhar Mannepalli Lakshmi Kantam 《应用有机金属化学》2015,29(4):234-239
Palladium nanoparticle‐incorporated metal–organic framework MIL‐101 (Pd/MIL‐101) was successfully synthesized and characterized using X‐ray diffraction, nitrogen physisorption, X‐ray photoelectron, UV–visible and infrared spectroscopies, and transmission electron microscopy. The characterization techniques confirmed high porosity and high surface area of MIL‐101 and high stability of nano‐size palladium particles. Pd/MIL‐101 nanocomposite was investigated for the Sonogashira cross‐coupling reaction of aryl and heteroaryl bromides with various alkynes under copper‐free conditions. The reusability of the catalyst was tested for up to four cycles without any significant loss in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
64.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
65.
66.
67.
68.
Dr. Antonio M. Rodríguez Dr. Pilar Prieto Prof. Antonio de la Hoz Prof. Ángel Díaz-Ortiz D. Raúl Martín Prof. José I. García 《ChemistryOpen》2015,4(3):308-317
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. 相似文献
69.
70.