全文获取类型
收费全文 | 146274篇 |
免费 | 29579篇 |
国内免费 | 15524篇 |
专业分类
化学 | 115621篇 |
晶体学 | 1708篇 |
力学 | 8074篇 |
综合类 | 920篇 |
数学 | 15726篇 |
物理学 | 49328篇 |
出版年
2024年 | 275篇 |
2023年 | 2394篇 |
2022年 | 3186篇 |
2021年 | 4194篇 |
2020年 | 5768篇 |
2019年 | 6561篇 |
2018年 | 4841篇 |
2017年 | 4410篇 |
2016年 | 8548篇 |
2015年 | 8565篇 |
2014年 | 9789篇 |
2013年 | 12282篇 |
2012年 | 13255篇 |
2011年 | 12991篇 |
2010年 | 10145篇 |
2009年 | 10046篇 |
2008年 | 10182篇 |
2007年 | 8595篇 |
2006年 | 7859篇 |
2005年 | 6722篇 |
2004年 | 5379篇 |
2003年 | 4470篇 |
2002年 | 5064篇 |
2001年 | 3955篇 |
2000年 | 3528篇 |
1999年 | 2753篇 |
1998年 | 2028篇 |
1997年 | 1958篇 |
1996年 | 1886篇 |
1995年 | 1585篇 |
1994年 | 1420篇 |
1993年 | 1203篇 |
1992年 | 1024篇 |
1991年 | 915篇 |
1990年 | 767篇 |
1989年 | 582篇 |
1988年 | 452篇 |
1987年 | 362篇 |
1986年 | 386篇 |
1985年 | 304篇 |
1984年 | 174篇 |
1983年 | 145篇 |
1982年 | 113篇 |
1981年 | 69篇 |
1980年 | 51篇 |
1979年 | 29篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1957年 | 34篇 |
1925年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
31.
Hu Duo-Duo Gao Qian Dai Jing-Cheng Cui Ru Li Yuan-Bo Li Yuan-Ming Zhou Xiao-Guo Bian Kang-Jie Wu Bing-Bing Zhang Kai-Fan Wang Xi-Sheng Li Yan 《中国科学:化学(英文版)》2022,65(4):753-761
Science China Chemistry - A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported. This methodology exhibited mild conditions,... 相似文献
32.
Wei Yuting Wang Qihua Liu Wei 《Annals of the Institute of Statistical Mathematics》2021,73(3):535-553
Annals of the Institute of Statistical Mathematics - In this paper, a model averaging approach is developed for the linear regression models with response missing at random. It is shown that the... 相似文献
33.
Xu Mengtao Li Changyou Sun Yang Yang Tianzhi Zhang Hongzhuang Liu Zhendong Liu Haiyang Li Zhenyuan Zhang Yimin 《Nonlinear dynamics》2021,105(4):3061-3092
Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are... 相似文献
34.
International Journal of Theoretical Physics - The Majorana representation, which provides an intuitive way to represent the quantum state by stars on the Bloch sphere, has drawn considerable... 相似文献
35.
Donglei Wei Huili Li Chuanqing Yang Jianmin Fu Hou Chen Liangjiu Bai Wenxiang Wang Huawei Yang Lixia Yang Ying Liang 《Journal of polymer science. Part A, Polymer chemistry》2022,60(10):1588-1594
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst. 相似文献
36.
Zhang Tinggui Xi Ya Fei Shao-Ming 《International Journal of Theoretical Physics》2021,60(8):2909-2915
We study the Bell nonlocality of high dimensional quantum systems based on quantum entanglement. A quantitative relationship between the maximal expectation value B of Bell operators and the quantum entanglement concurrence C is obtained for even dimension pure states, with the upper and lower bounds of B governed by C.
相似文献37.
Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device. 相似文献
38.
Nonlinear Dynamics - This paper investigates the guaranteed cost positive consensus for linear multi-agent systems (MASs) with multiple time-varying delays and switching topologies. First,... 相似文献
39.
In this article, we construct and analyze a residual-based a posteriori error estimator for a quadratic finite volume method (FVM) for solving nonlinear elliptic partial differential equations with homogeneous Dirichlet boundary conditions. We shall prove that the a posteriori error estimator yields the global upper and local lower bounds for the norm error of the FVM. So that the a posteriori error estimator is equivalent to the true error in a certain sense. Numerical experiments are performed to illustrate the theoretical results. 相似文献
40.