全文获取类型
收费全文 | 284篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 192篇 |
晶体学 | 1篇 |
力学 | 12篇 |
数学 | 35篇 |
物理学 | 59篇 |
出版年
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2016年 | 14篇 |
2015年 | 15篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 21篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 15篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 6篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1869年 | 1篇 |
排序方式: 共有299条查询结果,搜索用时 31 毫秒
1.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Minaeva Alexandra P. Goloveshkin Alexander S. Hansford Karl A. Egorov Mikhail P. 《Molecular diversity》2020,24(4):1327-1342
Molecular Diversity - A novel five-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Knoevenagel condensation–Michael addition–Mannich cascade... 相似文献
2.
3.
Fangyuan Zhang Evripidis Michail Fridolin Saal Ana-Maria Krause Dr. Prince Ravat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16241-16245
Herein, we have synthesized an enantiomerically pure propeller-shaped PAH, C90H48, possessing three [7]helicene and three [5]helicene subunits. This compound can be obtained in gram quantities in a straightforward manner. The photophysical and chiroptical properties were investigated using UV/Vis absorption and emission, optical rotation and circular dichroism spectroscopy, supported by DFT calculations. The nonlinear optical properties were investigated by two-photon absorption measurements using linearly and circularly polarized light. The extremely twisted structure and packing of the homochiral compound were investigated by single-crystal X-ray diffraction analysis. 相似文献
4.
Dr. Anton Lishchynskyi Dr. Fedor M. Miloserdov Dr. Eddy Martin Dr. Jordi Benet‐Buchholz Eduardo C. Escudero‐Adán Dr. Andrey I. Konovalov Dr. Vladimir V. Grushin 《Angewandte Chemie (International ed. in English)》2015,54(50):15289-15293
First evidence for the existence of free trifluoromethyl anion CF3? has been obtained. The 3D‐caged potassium cation in [K(crypt‐222)]+ is inaccessible to CF3?, thus rendering it uncoordinated (“naked”). Ionic [K(crypt‐222)]+ CF3? has been characterized by single‐crystal X‐ray diffraction, solution NMR spectroscopy, DFT calculations, and reactivity toward electrophiles. 相似文献
5.
6.
Ekaterina E. Stoikova Michail I. Sorvin Dmitry N. Shurpik Herman C. Budnikov Ivan I. Stoikov Gennady A. Evtugyn 《Electroanalysis》2015,27(2):440-449
A novel potentiometric sensor based on screen‐printed carbon electrode covered with electropolymerized polyaniline (PANI) and unsubstituted pillar[5]arene as ionophore has been developed and tested in potentiometric measurements of pH and metal ions. The introduction of pillar[5]arene improved the reversibility of the pH response in the range from 2.0 to 9.0 with the slope of 45 mV/pH. Among metal cations, the response to Fe3+ and Ag+ ions was referred to PANI redox conversion whereas the signal toward Cu2+ in the range from 1.0×10?6 to 1.0×10?2 M (limit of detection (LOD) 3.0×10?7 M) to specific interaction with the macrocycle. 相似文献
7.
A mathematical model based on a straightforward geometrical background is developed which enables predictions of a transition of one dispersed phase to a cocontinuous one (i.e., the percolation threshold) on addition of another dispersed phase during melt mixing in ternary polymer blends. The present work concerns only ternary blends with two separate dispersions of the inner phases in which no encapsulation takes place. In addition, in order to simplify the model, one of the inner phases was represented by hard, nondeformable microspheres The expression developed describes well an experimental relationship between the percolation threshold, the concentration above which the former dispersed phase transforms to a continuous one, and concentrations of both inner phases. The results agree well with the experimental data obtained in a previous work. 相似文献
8.
9.
Andrey N. Komogortsev Boris V. Lichitsky Alexander D. Tretyakov Artem N. Fakhrutdinov Arkady A. Dudinov Michail M. Krayushkin 《Journal of heterocyclic chemistry》2019,56(11):3081-3087
A convenient approach to the synthesis of the previously unknown 7H‐furo[3,2‐b]pyran‐7‐ones based on the intramolecular cyclization of carbonyl derivatives of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one has been elaborated. Key intermediates in the synthesis of the target 7H‐furo[3,2‐b]pyran‐7‐ones are 3‐hydroxy‐6‐methyl‐2‐(2‐oxo‐2‐arylethyl)‐4H‐pyran‐4‐ones. They are formed as a result of multicomponent condensation of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one with arylglyoxals and 4‐methoxyaniline. 相似文献
10.