全文获取类型
收费全文 | 2307篇 |
免费 | 115篇 |
国内免费 | 1篇 |
专业分类
化学 | 1644篇 |
晶体学 | 18篇 |
力学 | 50篇 |
数学 | 255篇 |
物理学 | 456篇 |
出版年
2024年 | 8篇 |
2023年 | 23篇 |
2022年 | 72篇 |
2021年 | 87篇 |
2020年 | 84篇 |
2019年 | 112篇 |
2018年 | 109篇 |
2017年 | 81篇 |
2016年 | 138篇 |
2015年 | 94篇 |
2014年 | 111篇 |
2013年 | 152篇 |
2012年 | 142篇 |
2011年 | 182篇 |
2010年 | 104篇 |
2009年 | 82篇 |
2008年 | 117篇 |
2007年 | 114篇 |
2006年 | 111篇 |
2005年 | 91篇 |
2004年 | 68篇 |
2003年 | 52篇 |
2002年 | 51篇 |
2001年 | 19篇 |
2000年 | 18篇 |
1999年 | 18篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有2423条查询结果,搜索用时 15 毫秒
81.
82.
Michael A. Pudovik Lyudmila Kibardina Alexey Trifonov Alexey Dobrynin Sergei Katsyuba Alexander Burilov 《Phosphorus, sulfur, and silicon and the related elements》2019,194(1-2):120-126
New O-phosphorylated pyridoxal derivatives have been synthesized through the reaction of azomethines with РV acid chlorides. 2-Chloro-2-thioxo-5,5-dimethyl-1,3,2-dioxaphosphinanes and diethylchlorothiophosphate have been employed as phosphorylating agents. Regardless of the nature of the phosphorylating agent, the reaction is regioselective at phenolic hydroxyl group. The structure of final products is determined by the nature of the substituent at the nitrogen atom. If R is alkyl or cycloalkyl group, the products of the reaction represent phosphorylated pyridoxal imines, whereas phosphorylated furopyridines are formed in the case R is aryl substituent. 相似文献
83.
Georgios Velkos Denis S. Krylov Kyle Kirkpatrick Lukas Spree Vasilii Dubrovin Bernd Büchner Stanislav M. Avdoshenko Valeriy Bezmelnitsyn Sean Davis Paul Faust James Duchamp Harry C. Dorn Alexey A. Popov 《Angewandte Chemie (International ed. in English)》2019,58(18):5891-5896
The azafullerene Tb2@C79N is found to be a single‐molecule magnet with a high 100‐s blocking temperature of magnetization of 24 K and large coercivity. Tb magnetic moments with an easy‐axis single‐ion magnetic anisotropy are strongly coupled by the unpaired spin of the single‐electron Tb?Tb bond. Relaxation of magnetization in Tb2@C79N below 15 K proceeds via quantum tunneling of magnetization with the characteristic time τQTM=16 462±1230 s. At higher temperature, relaxation follows the Orbach mechanism with a barrier of 757±4 K, corresponding to the excited states, in which one of the Tb spins is flipped. 相似文献
84.
85.
Panov Alexey A. Lakatosh Sergey A. Kubbutat Michael H. G. Dezhenkova Lyubov G. Totzke Frank Schechtel Kristof 《Chemistry of Heterocyclic Compounds》2019,55(11):1050-1059
Chemistry of Heterocyclic Compounds - Several previously unknown derivatives of 3,4-bis(indol-1-yl)maleimide, as well as 3-(2,3-dihydroindol-1-yl)-4-(indol-1-yl)maleimide were synthesized as... 相似文献
86.
Bumagin Nikolay A. Petkevich Sergey K. Kletskov Alexey V. Alekseyev Roman S. Potkin Vladimir I. 《Chemistry of Heterocyclic Compounds》2019,55(6):508-516
Chemistry of Heterocyclic Compounds - N-(4,6-Dimethylpyrimidin-2-yl)-5-phenylisoxazole-3-carboxamide was used as a ligand for obtaining bimetallic boron-containing heterogeneous catalysts... 相似文献
87.
Set-Valued and Variational Analysis - For any linear transformation and two convex closed sets, we provide necessary and sufficient conditions for the transformation of the intersection of the sets... 相似文献
88.
Philipp Rietsch Dr. Sebastian Sobottka Dr. Katrin Hoffmann Dr. Alexey A. Popov Pascal Hildebrandt Prof. Dr. Biprajit Sarkar Dr. Ute Resch-Genger Prof. Dr. Siegfried Eigler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17361-17365
Reversibly switching the light absorption of organic molecules by redox processes is of interest for applications in sensors, light harvesting, smart materials, and medical diagnostics. This work presents a symmetrical benzothiadiazole (BTD) derivative with a high fluorescence quantum yield in solution and in the crystalline state and shows by spectroelectrochemical analysis that reversible switching of UV absorption in the neutral state, to broadband Vis/NIR absorption in the 1st oxidized state, to sharp band Vis absorption in the 2nd oxidized state, is possible. For the one-electron oxidized species, formation of a delocalized radical is confirmed by electron paramagnetic resonance spectroelectrochemistry. Furthermore, our results reveal an increasing quinoidal distortion upon the 1st and 2nd oxidation, which can be used as the leitmotif for the development of BTD based redox switches. 相似文献
89.
Dr. Ksenia S. Egorova Alexey S. Galushko Prof. Valentine P. Ananikov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(50):22480-22489
In this Essay, we present a critical analysis of two common practices in modern chemistry—that is, of using speculations about the “greenness” and “nontoxicity” of developed synthesis procedures and of a priori labelling various compounds derived from natural sources as being environmentally safe. We note that every organic molecule that contains functional groups should be biologically active. Thus, analysis of the particular greenness and the potential environmental impact of a given chemical process should account for the biological activity of all its components in a measureable (rather than empirical) way. We highlight the necessity of clarifying discussions on biological activity and toxicity and propose possible ways of introducing tox-Profiles as a reliable overview of the overall toxicity of chemical reactions. 相似文献
90.
Khadichakhan Rafikova Nil Ertekin Binbay Nermin Meriç Aygul Kerimkulova Alexey Zazybin Veysel Binbay Veysi Okumuş Cezmi Kayan Uğur Işik Nevin Arslan Murat Aydemir 《应用有机金属化学》2020,34(7):e5658
Four metal complexes, IL-OPPh2-Ru-p-cymene (3) , IL-OPPh2-Ru-benzene (4) , IL-OPPh2-Ir-Cp* (5) , IL-OPPh2-Rh-COD (6) , have been evaluated for in vitro antioxidant activity such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power activity. Maximum scavenging activity (71.43%) was obtained with IL-OPPh2-Ru-p-cymene, whereas IL-OPPh2-Rh-COD showed the highest reducing power ability. The complexes were also studied for their antimicrobial activity against three Gram-positive and three Gram-negative bacteria. In addition, DNA binding of the complexes was evaluated using calf thymus DNA. Both Ru(II) complexes exhibited good DNA-binding activity while the other complexes did not have any activity. Furthermore, ab initio quantum calculations of four complexes were also carried out using density functional theory to better understand their chemical behaviors. 相似文献