全文获取类型
收费全文 | 109950篇 |
免费 | 28984篇 |
国内免费 | 20443篇 |
专业分类
化学 | 71837篇 |
晶体学 | 1349篇 |
力学 | 7403篇 |
综合类 | 217篇 |
数学 | 13372篇 |
物理学 | 65199篇 |
出版年
2024年 | 562篇 |
2023年 | 1457篇 |
2022年 | 2062篇 |
2021年 | 2087篇 |
2020年 | 2430篇 |
2019年 | 2893篇 |
2018年 | 2676篇 |
2017年 | 3174篇 |
2016年 | 3927篇 |
2015年 | 4051篇 |
2014年 | 4349篇 |
2013年 | 6668篇 |
2012年 | 7431篇 |
2011年 | 8949篇 |
2010年 | 11204篇 |
2009年 | 11333篇 |
2008年 | 5519篇 |
2007年 | 4735篇 |
2006年 | 4347篇 |
2005年 | 4264篇 |
2004年 | 4773篇 |
2003年 | 3840篇 |
2002年 | 3615篇 |
2001年 | 3750篇 |
2000年 | 2847篇 |
1999年 | 3199篇 |
1998年 | 2712篇 |
1997年 | 2523篇 |
1996年 | 2832篇 |
1995年 | 3177篇 |
1994年 | 3162篇 |
1993年 | 3155篇 |
1992年 | 2723篇 |
1991年 | 2327篇 |
1990年 | 1983篇 |
1989年 | 2014篇 |
1988年 | 1941篇 |
1987年 | 1226篇 |
1986年 | 1299篇 |
1985年 | 930篇 |
1984年 | 1017篇 |
1982年 | 922篇 |
1981年 | 754篇 |
1980年 | 781篇 |
1979年 | 531篇 |
1978年 | 530篇 |
1977年 | 633篇 |
1976年 | 1042篇 |
1973年 | 436篇 |
1972年 | 532篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Peng-Yan Gui Xiao-Hui Yan Wen-Juan Yuan Yuan-Liang Ma Xiao Ding Shuai Liu 《Natural product research》2019,33(19):2830-2836
A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme. 相似文献
32.
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
33.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
34.
Effect of the dispersion on multipartite continuous-variable entanglement in optical parametric amplifier 下载免费PDF全文
Based on the quantum fluctuations, we adopt the method of generalized V1 criterion to investigate multipartite entanglement characteristics in an optical parametric amplification system with the consideration of dispersion. The nonlinear interaction becomes strong because of the existence of dispersion coefficient σ. Considering the influence of dispersion factor σ, with increasing the pump parameter μ, the value of minimum variance V1 decreases and the squeezing curve nearly equals 1/(1 + μ). The larger particle number N results in a smaller variance and higher entanglement. 相似文献
35.
Liming Fan Feng Wang Dongsheng Zhao Yuxin Peng Yuxin Deng Yinwei Luo Xiutang Zhang 《应用有机金属化学》2020,34(12):e5960
Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)0.5(bimb)]·H2O}n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {86} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium. 相似文献
36.
37.
38.
Dr. Feifan Wang Jie Tian Dr. Mengzhu Li Dr. Weizhen Li Dr. Lifang Chen Xiaozhi Liu Dr. Jian Li Aidaer Muhetaer Prof. Dr. Qi Li Prof. Dr. Yuan Wang Prof. Dr. Lin Gu Prof. Dr. Ding Ma Prof. Dr. Dongsheng Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(21):8280-8286
Fully utilizing solar energy for catalysis requires the integration of conversion mechanisms and therefore delicate design of catalyst structures and active species. Herein, a MOF crystal engineering method was developed to controllably synthesize a copper–ceria catalyst with well-dispersed photoactive Cu-[O]-Ce species. Using the preferential oxidation of CO as a model reaction, the catalyst showed remarkably efficient and stable photoactivated catalysis, which found practical application in feed gas treatment for fuel cell gas supply. The coexistence of photochemistry and thermochemistry effects contributes to the high efficiency. Our results demonstrate a catalyst design approach with atomic or molecular precision and a combinatorial photoactivation strategy for solar energy conversion. 相似文献
39.
40.
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13... 相似文献