全文获取类型
收费全文 | 87500篇 |
免费 | 25885篇 |
国内免费 | 19061篇 |
专业分类
化学 | 56895篇 |
晶体学 | 1275篇 |
力学 | 5856篇 |
综合类 | 201篇 |
数学 | 11119篇 |
物理学 | 57100篇 |
出版年
2024年 | 481篇 |
2023年 | 1112篇 |
2022年 | 1337篇 |
2021年 | 1359篇 |
2020年 | 1693篇 |
2019年 | 2166篇 |
2018年 | 1981篇 |
2017年 | 2533篇 |
2016年 | 2839篇 |
2015年 | 3183篇 |
2014年 | 3069篇 |
2013年 | 4981篇 |
2012年 | 5515篇 |
2011年 | 6983篇 |
2010年 | 9968篇 |
2009年 | 10262篇 |
2008年 | 4210篇 |
2007年 | 3537篇 |
2006年 | 3125篇 |
2005年 | 3387篇 |
2004年 | 4100篇 |
2003年 | 3286篇 |
2002年 | 3116篇 |
2001年 | 3324篇 |
2000年 | 2522篇 |
1999年 | 2695篇 |
1998年 | 2270篇 |
1997年 | 2044篇 |
1996年 | 2377篇 |
1995年 | 2797篇 |
1994年 | 2845篇 |
1993年 | 2915篇 |
1992年 | 2477篇 |
1991年 | 2116篇 |
1990年 | 1781篇 |
1989年 | 1870篇 |
1988年 | 1853篇 |
1987年 | 1146篇 |
1986年 | 1204篇 |
1985年 | 866篇 |
1984年 | 983篇 |
1982年 | 891篇 |
1981年 | 733篇 |
1980年 | 771篇 |
1979年 | 531篇 |
1978年 | 533篇 |
1977年 | 635篇 |
1976年 | 1044篇 |
1973年 | 439篇 |
1972年 | 532篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been deemed as clean and sustainable strategies to solve the energy crisis and environmental problems. Various catalysts have been developed to promote the process of HER and OER. Among them, two-dimensional covalent organic frameworks (2D COFs) have received great attention due to their diverse and designable structure. In this minireview, we mainly summarize the diverse linkages of 2D COFs and strategies for enhancing the catalytic performance of 2D COFs for HER and OER, such as introducing active building blocks, metal ions and tailored linkages. Furthermore, a brief outlook for the development directions of COFs in the field of HER and OER is provided, expecting to stimulate new opportunities in future research. 相似文献
13.
14.
In the view of substrate availability, atomic efficiency and cost, directly using arenols as coupling partners in cross‐coupling, would be one of the most attractive goals. Up to date, many efforts have been made to activate the C—O bond of phenols with different strategies, for example, through in‐situ formed intermediates, through a catalytic reductive dearomatization‐condensation‐rearomatization sequence or catalytic deoxygenation. In this review, we summarized recent advances in cross‐couplings of arenols as the electrophiles via C—O activation. 相似文献
15.
16.
Hierarchical motion planning at the acceleration level based on task priority matrix for space robot
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to... 相似文献
17.
Nonlinear Dynamics - Conventional tuned liquid column dampers (TLCDs) are deficient in multidirectionality. In contrast, toroidal TLCDs are designed to extend the application to multidirectional... 相似文献
19.
20.
Nonclassical light states are important for both conceptual and practical reasons: they are basic ingredients in testing and exploring quantum foundations, and are crucial resources in quantum technologies. Various useful criteria have been developed to detect nonclassicality in the literature, and several meaningful measures of nonclassicality have been introduced and measured experimentally. In this work, by use of a non-Hermitian generalization of the Wigner-Yanase-Dyson skew information and playing with operator ordering in evaluating average photon number, we develop a novel family of criteria for detecting nonclassicality of light based on Lieb's concavity, which is a deep and powerful result concerning interaction between quantum states and observables. We elucidate the information-theoretic as well as the physical meaning of the criteria, and illustrate their effectiveness in capturing and quantifying nonclassicality of various important light states. 相似文献