全文获取类型
收费全文 | 390494篇 |
免费 | 8034篇 |
国内免费 | 5741篇 |
专业分类
化学 | 188303篇 |
晶体学 | 5793篇 |
力学 | 22122篇 |
综合类 | 323篇 |
数学 | 67347篇 |
物理学 | 120381篇 |
出版年
2021年 | 3375篇 |
2020年 | 3889篇 |
2019年 | 4296篇 |
2018年 | 15075篇 |
2017年 | 14733篇 |
2016年 | 12700篇 |
2015年 | 5345篇 |
2014年 | 7340篇 |
2013年 | 14720篇 |
2012年 | 15599篇 |
2011年 | 24034篇 |
2010年 | 15808篇 |
2009年 | 16099篇 |
2008年 | 18845篇 |
2007年 | 20683篇 |
2006年 | 11763篇 |
2005年 | 11611篇 |
2004年 | 10919篇 |
2003年 | 10324篇 |
2002年 | 9483篇 |
2001年 | 9521篇 |
2000年 | 7371篇 |
1999年 | 5783篇 |
1998年 | 5080篇 |
1997年 | 4749篇 |
1996年 | 4606篇 |
1995年 | 4085篇 |
1994年 | 4043篇 |
1993年 | 4077篇 |
1992年 | 4135篇 |
1991年 | 4346篇 |
1990年 | 4070篇 |
1989年 | 3961篇 |
1988年 | 3849篇 |
1987年 | 3773篇 |
1986年 | 3579篇 |
1985年 | 4611篇 |
1984年 | 4788篇 |
1983年 | 3885篇 |
1982年 | 4104篇 |
1981年 | 3942篇 |
1980年 | 3817篇 |
1979年 | 4023篇 |
1978年 | 4118篇 |
1977年 | 4007篇 |
1976年 | 4197篇 |
1975年 | 3800篇 |
1974年 | 3821篇 |
1973年 | 3894篇 |
1972年 | 2867篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
61.
Sarah Peluse 《Israel Journal of Mathematics》2018,227(1):379-396
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser. 相似文献
62.
Nishio Yu Komori Kohei Izawa Seiichiro Fukunishi Yu 《Theoretical and Computational Fluid Dynamics》2020,34(1):105-117
Theoretical and Computational Fluid Dynamics - The present study aims to simulate a collision of two droplets containing immiscible liquids by employing a three- dimensional incompressible smoothed... 相似文献
63.
Pd0‐Catalyzed Intramolecular α‐Arylation of Sulfones: Domino Reactions in the Synthesis of Functionalized Tetrahydroisoquinolines
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Prof.Dr. Daniel Solé Ferran Pérez‐Janer Dr. Raffaella Mancuso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(12):4580-4584
A new strategy for the synthesis of tetrahydroisoquinolines based on the Pd0‐catalyzed intramolecular α‐arylation of sulfones is reported. The combination of this Pd‐catalyzed reaction with intermolecular Michael and aza‐Michael reactions allows the development of two‐ and three‐step domino processes to synthesize diversely functionalized scaffolds from readily available starting materials. 相似文献
64.
65.
K.V. Stepurska О.О. Soldatkin I.S. Kucherenko V.M. Arkhypova S.V. Dzyadevych A.P. Soldatkin 《Analytica chimica acta》2015
This study was aimed at the development of a conductometric biosensor based on acetylcholinesterase considering the feasibility of its application for the inhibitory analysis of various toxicants. In this paper, the optimum conditions for enzyme immobilization on the transducer surface are selected as well as the optimum concentration of substrate for inhibitory analysis. Sensitivity of the developed biosensor to different classes of toxic compounds (organophosphorus pesticides, heavy metal ions, surfactants, aflatoxin, glycoalkaloids) was tested. It is shown that the developed biosensor can be successfully used for the analysis of pesticides and mycotoxins, as well as for determination of total toxicity of the samples. A new method of biosensor analysis of toxic substances of different classes in complex multicomponent aqueous samples is proposed. 相似文献
66.
67.
68.
Jie Lu Ju-Kang Wu Yao Jiang Dr. Peng Tan Lin Zhang Yu Lei Prof. Xiao-Qin Liu Prof. Lin-Bing Sun 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(16):6490-6496
Hierarchically porous metal–organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites. 相似文献
69.
Gurenkova Yu. S. Kornyakov I. V. Ostrovsky V. A. Skrylnikova M. A. Khramchikhin A. V. 《Russian Journal of General Chemistry》2020,90(7):1202-1206
Russian Journal of General Chemistry - 8-Phenyltetrazolo[5,1-b][1,3,4]thiadiazepine was obtained as a result of intermolecular cyclization of 1-amino-1H-tetrazole-5-thiol and 3-phenyl-2-propynal.... 相似文献
70.
V. A. Bespalov V. M. Glazov E. A. Il’ichev Yu. A. Klimov S. V. Kuklev A. E. Kuleshov R. M. Nabiev G. N. Petrukhin B. G. Potapov G. S. Rychkov D. S. Sokolov V. V. Fandeev E. A. Fetisov S. S. Yakushov 《Technical Physics》2015,60(4):553-560
The results of investigation of optical image detectors designed for the largest problem, near-VUV, range of the spectrum are presented. The possibility of using a dual-stage image detection system to appreciably lower the sensitivity threshold and make computer data processing feasible is considered. The integration of a UV module into a wideband image detector is studied. 相似文献