全文获取类型
收费全文 | 38422篇 |
免费 | 2001篇 |
国内免费 | 1811篇 |
专业分类
化学 | 18026篇 |
晶体学 | 398篇 |
力学 | 2004篇 |
综合类 | 106篇 |
数学 | 10218篇 |
物理学 | 11482篇 |
出版年
2023年 | 168篇 |
2022年 | 318篇 |
2021年 | 364篇 |
2020年 | 390篇 |
2019年 | 450篇 |
2018年 | 1533篇 |
2017年 | 1744篇 |
2016年 | 1215篇 |
2015年 | 1144篇 |
2014年 | 1078篇 |
2013年 | 1394篇 |
2012年 | 3979篇 |
2011年 | 3155篇 |
2010年 | 2490篇 |
2009年 | 2193篇 |
2008年 | 1234篇 |
2007年 | 1148篇 |
2006年 | 1083篇 |
2005年 | 4876篇 |
2004年 | 4316篇 |
2003年 | 2667篇 |
2002年 | 972篇 |
2001年 | 702篇 |
2000年 | 352篇 |
1999年 | 389篇 |
1998年 | 294篇 |
1997年 | 197篇 |
1996年 | 159篇 |
1995年 | 146篇 |
1994年 | 125篇 |
1993年 | 87篇 |
1992年 | 223篇 |
1991年 | 210篇 |
1990年 | 170篇 |
1989年 | 133篇 |
1988年 | 119篇 |
1987年 | 72篇 |
1986年 | 51篇 |
1985年 | 44篇 |
1984年 | 42篇 |
1983年 | 37篇 |
1979年 | 36篇 |
1976年 | 82篇 |
1975年 | 39篇 |
1974年 | 45篇 |
1973年 | 50篇 |
1972年 | 40篇 |
1969年 | 37篇 |
1968年 | 36篇 |
1966年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
D. Naidoo K. A?t-Ameur M. Brunel A. Forbes 《Applied physics. B, Lasers and optics》2012,106(3):683-690
In this paper we demonstrate experimentally the intra-cavity generation of a coherent superposition of Laguerre–Gaussian modes
of zero radial order but opposite azimuthal order. The superposition is created with a simple intra-cavity stop that creates
equal losses for the two azimuthal modes, and we show that by adjustment of the stop we can produce modes up to azimuthal
order 8. The fact that we have a coherent superposition rather than an incoherent superposition is verified by intensity measurements,
propagation measurements and a decomposition of the field by an inner product executed on a phase-only spatial light modulator.
Such fields have relevance in quantum information and optical trapping. 相似文献
994.
995.
Synthesis of multi‐functionalized carbonyl compounds by palladium–catalysed γ‐substitution of MBH adducts with activated amides
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)
Gao Pei‐Sen Zhang Jin‐Lei Li Ning Zheng Zhan Jiang Yuan Yang Gao Zi‐Wei Zhang Weiqiang Xu Li‐Wen 《应用有机金属化学》2018,32(3)
Catalytic allylic γ‐substitution with Morita‐Baylis‐Hillman (MBH) adducts for creating a new family of unsymmetrical dicarbonyl compounds was presented in this work, in which a variety of allylated amide products were achieved in good yields and high regioselectivity with excellent linear‐to‐branched ratios. Especially, it was found that the Pd/HZNU‐Phos complex exhibited remarkably high activity (with a TON up to 16800) in this transformation between dicarbonyl amides and MBH adducts. In addition, the possibly multisite interaction between multifunctional Pd/HZNU‐Phos catalyst system and substrates might responsible for its exceptionally high efficiency in this reaction. 相似文献
996.
997.
Lionel Mathelin Olivier P. Le Ma?tre 《Theoretical and Computational Fluid Dynamics》2012,26(5):415-434
This paper describes a rigorous a posteriori error analysis for the stochastic solution of non-linear uncertain chemical models. The dual-based a posteriori stochastic error analysis extends the methodology developed in the deterministic finite elements context to stochastic discretization frameworks. It requires the resolution of two additional (dual) problems to yield the local error estimate. The stochastic error estimate can then be used to adapt the stochastic discretization. Different anisotropic refinement strategies are proposed, leading to a cost-efficient tool suitable for multi-dimensional problems of moderate stochastic dimension. The adaptive strategies allow both for refinement and coarsening of the stochastic discretization, as needed to satisfy a prescribed error tolerance. The adaptive strategies were successfully tested on a model for the hydrogen oxidation in supercritical conditions having 8 random parameters. The proposed methodologies are however general enough to be also applicable for a wide class of models such as uncertain fluid flows. 相似文献
998.
999.
1000.
Wang Zhongtang Wen Wei Quan Wei Du Liang Wang Ping Lin Jinxian Xie Yun Tan Zhaoyi 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):411-417
Journal of Radioanalytical and Nuclear Chemistry - Plutonium is one of the key radionuclides in nuclear decommission. In this study, a rapid method was developed to analyze Pu for concrete samples... 相似文献