全文获取类型
收费全文 | 2993篇 |
免费 | 548篇 |
国内免费 | 324篇 |
专业分类
化学 | 2200篇 |
晶体学 | 37篇 |
力学 | 188篇 |
综合类 | 21篇 |
数学 | 299篇 |
物理学 | 1120篇 |
出版年
2024年 | 8篇 |
2023年 | 91篇 |
2022年 | 90篇 |
2021年 | 131篇 |
2020年 | 165篇 |
2019年 | 145篇 |
2018年 | 138篇 |
2017年 | 87篇 |
2016年 | 180篇 |
2015年 | 141篇 |
2014年 | 188篇 |
2013年 | 197篇 |
2012年 | 285篇 |
2011年 | 318篇 |
2010年 | 186篇 |
2009年 | 218篇 |
2008年 | 206篇 |
2007年 | 160篇 |
2006年 | 144篇 |
2005年 | 116篇 |
2004年 | 93篇 |
2003年 | 74篇 |
2002年 | 70篇 |
2001年 | 56篇 |
2000年 | 54篇 |
1999年 | 54篇 |
1998年 | 43篇 |
1997年 | 32篇 |
1996年 | 50篇 |
1995年 | 24篇 |
1994年 | 30篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 15篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1974年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有3865条查询结果,搜索用时 109 毫秒
91.
92.
Science China Physics, Mechanics & Astronomy - To pre-compress the disk-shaped LY12 samples along the radial direction can be done with the aid of overstress assembly by heating or by... 相似文献
93.
94.
Applied Mathematics and Mechanics - The recently developed hard-magnetic soft (HMS) materials can play a significant role in the actuation and control of medical devices, soft robots, flexible... 相似文献
95.
96.
Rong Chen Zhijun Qiao Shouming Zhou 《Mathematical Methods in the Applied Sciences》2019,42(18):6999-7010
Considered herein is a two‐component Novikov equations (called Geng‐Xue system for short) with cubic nonlinearities. The persistence properties and some unique continuation properties of the solutions to the system in weighted Lp spaces are established. Moreover, a wave‐breaking criterion for strong solutions is determined in the lowest Sobolev space by using the localization analysis in the transport equation theory, and we also give a lower bound for the maximal existence time. 相似文献
97.
98.
Chenyang Fan Chonglin Song Gang Lv Jiangjun Wei Xuyang Zhang Yuehan Qiao Ye Liu 《Proceedings of the Combustion Institute》2019,37(4):4821-4829
Post injection has significant benefit in the reduction of diesel soot emissions. Therefore, there is a need to understand the effect of post-injection strategy on soot physicochemical properties and reactivity because they play an important role in soot oxidation process that governs the final soot emissions. This work focuses on the impact of post injection on the physicochemical properties and reactivity of diesel in-cylinder soot using a main plus post injection (M*P) and a single injection (M) strategy. The soot was sampled by a developed total cylinder sampling system, and the dividing points of soot formation-dominant and oxidation-dominant phases were used for studying the impacts of post injection on the characteristics of in-cylinder soot. The physicochemical properties of the soot samples, including primary particle size, nanostructure, carbon chemical state and surface functional groups, were characterized. The soot reactivity was evaluated in terms of peak temperature, burnout temperature and apparent activation energy. In the oxidation-dominant phase, the M*P soot initially possesses smaller primary particle size, shorter fringe length, larger tortuosity, lower sp2/sp3 hybridization ratio of carbon atoms and higher content of aliphatic CH groups than the M soot. The beneficial influence of physicochemical properties on soot reactivity when using post injection is validated by the thermogravimetric data, which shows that the M*P soot is more reactive than the M soot at the onset of the oxidation-dominant phase. In the M*P case, the soot generated from the main-injection combustion has lower reactivity than the soot from the post-injection combustion after they experience the soot formation-dominant phase. The results indicate that the use of post injection leads to in-cylinder soot with physicochemical properties that favor reactivity. The enhancement of reactivity means that the soot will be more readily oxidized in the subsequent combustion process, and consequently contributes to a reduction in final soot emissions. 相似文献
99.