全文获取类型
收费全文 | 198274篇 |
免费 | 5969篇 |
国内免费 | 3865篇 |
专业分类
化学 | 112082篇 |
晶体学 | 2801篇 |
力学 | 9010篇 |
综合类 | 241篇 |
数学 | 21223篇 |
物理学 | 62751篇 |
出版年
2022年 | 1355篇 |
2021年 | 1778篇 |
2020年 | 2000篇 |
2019年 | 2044篇 |
2018年 | 1936篇 |
2017年 | 1926篇 |
2016年 | 3425篇 |
2015年 | 3040篇 |
2014年 | 3834篇 |
2013年 | 9551篇 |
2012年 | 8477篇 |
2011年 | 10340篇 |
2010年 | 6613篇 |
2009年 | 6726篇 |
2008年 | 9178篇 |
2007年 | 8988篇 |
2006年 | 8521篇 |
2005年 | 7861篇 |
2004年 | 6916篇 |
2003年 | 5920篇 |
2002年 | 5813篇 |
2001年 | 6693篇 |
2000年 | 5139篇 |
1999年 | 4038篇 |
1998年 | 3133篇 |
1997年 | 3061篇 |
1996年 | 3052篇 |
1995年 | 2673篇 |
1994年 | 2521篇 |
1993年 | 2365篇 |
1992年 | 2656篇 |
1991年 | 2577篇 |
1990年 | 2244篇 |
1989年 | 2185篇 |
1988年 | 2191篇 |
1987年 | 2086篇 |
1986年 | 1999篇 |
1985年 | 2917篇 |
1984年 | 2854篇 |
1983年 | 2265篇 |
1982年 | 2448篇 |
1981年 | 2319篇 |
1980年 | 2267篇 |
1979年 | 2220篇 |
1978年 | 2270篇 |
1977年 | 2227篇 |
1976年 | 2160篇 |
1975年 | 2153篇 |
1974年 | 2055篇 |
1973年 | 2138篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
31.
32.
33.
Single Crystal to Single Crystal (SC‐to‐SC) Transformation from a Nonporous to Porous Metal–Organic Framework and Its Application Potential in Gas Adsorption and Suzuki Coupling Reaction through Postmodification
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Rupam Sen Debraj Saha Dr. Subratanath Koner Dr. Paula Brandão Dr. Zhi Lin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5962-5971
A new amino‐functionalized strontium–carboxylate‐based metal–organic framework (MOF) has been synthesized that undergoes single crystal to single crystal (SC‐to‐SC) transformation upon desolvation. Both structures have been characterized by single‐crystal X‐ray analysis. The desolvated structure shows an interesting 3D porous structure with pendent ?NH2 groups inside the pore wall, whereas the solvated compound possesses a nonporous structure with DMF molecules on the metal centers. The amino group was postmodified through Schiff base condensation by pyridine‐2‐carboxaldehyde and palladium was anchored on that site. The modified framework has been utilized for the Suzuki cross‐coupling reaction. The compound shows high activity towards the C?C cross‐coupling reaction with good yields and turnover frequencies. Gas adsorption studies showed that the desolvated compound had permanent porosity and was microporous in nature with a BET surface area of 2052 m2 g?1. The material also possesses good CO2 (8 wt %) and H2 (1.87 wt %) adsorption capabilities. 相似文献
34.
Ahmed Waqar Chowdhury Z. Z. Kazi S. N. Johan MR. Akram Naveed Oon C. S. Abdelrazek Ali H. 《Journal of Thermal Analysis and Calorimetry》2021,144(4):1517-1534
Journal of Thermal Analysis and Calorimetry - In recent decades, the growth of heat transfer using nanomaterials in the conventional base fluid has caught the attention of researchers... 相似文献
35.
36.
37.
38.
39.
Erosion and sediments transport processes have a great impact on industrial structures and on water quality. Despite its limitations, the Saint‐Venant‐Exner system is still (and for sure for some years) widely used in industrial codes to model the bedload sediment transport. In practice, its numerical resolution is mostly handled by a splitting technique that allows a weak coupling between hydraulic and morphodynamic distinct softwares but may suffer from important stability issues. In recent works, many authors proposed alternative methods based on a strong coupling that cure this problem but are not so trivial to implement in an industrial context. In this work, we then pursue 2 objectives. First, we propose a very simple scheme based on an approximate Riemann solver, respecting the strong coupling framework, and we demonstrate its stability and accuracy through a number of numerical test cases. However, second, we reinterpret our scheme as a splitting technique and we extend the purpose to propose what should be the minimal coupling that ensures the stability of the global numerical process in industrial codes, at least, when dealing with collocated finite volume method. The resulting splitting method is, up to our knowledge, the only one for which stability properties are fully demonstrated. 相似文献
40.