全文获取类型
收费全文 | 385篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 222篇 |
晶体学 | 14篇 |
力学 | 9篇 |
数学 | 25篇 |
物理学 | 81篇 |
无线电 | 49篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 28篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 12篇 |
2013年 | 44篇 |
2012年 | 24篇 |
2011年 | 30篇 |
2010年 | 12篇 |
2009年 | 9篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 62 毫秒
101.
Structural Chemistry - G-protein–coupled receptors are integral membrane proteins involved in signal transduction pathways, making them an appealing drug targets for a wide spectrum of... 相似文献
102.
Tanwistha Ghosh Shinji Nagasawa Neethi Raveendran Vibhu Darshan Akinori Saeki Vijayakumar C. Nair 《化学:亚洲杂志》2019,14(7):963-967
Precise control over the supramolecular organization of organic semiconducting materials guiding to exclusive face‐on or edge‐on orientation is a challenging task. In the present work, we study the preferential packing of thiophene oligomers induced through rational molecular designing and self‐assembly. The acceptor–donor–acceptor‐type oligomers having 2‐(1,1‐dicyano‐methylene)rhodanine as acceptor ( OT1 ) favored a face‐on packing, whereas that of functionalized with N‐octyl rhodanine ( OT2 ) preferred an edge‐on packing as evident from 2D‐grazing incidence angle X‐ray diffraction, tapping‐mode atomic force microscopy (AFM) and Raman spectroscopy analyses. The oligomers exhibited anisotropic conductivity in the self‐assembled state as an outcome of the preferred orientation, revealed by the conducting AFM experiment. 相似文献
103.
Vijayakumar V. Priyan M. K. Ushadevi G Varatharajan R. Manogaran Gunasekaran Tarare Prathamesh Vijay 《Mobile Networks and Applications》2019,24(3):1034-1045
Mobile Networks and Applications - In the present era of Information Technology, almost all big and small scale companies are moving towards cloud to store and manage the data. Cloud computing is a... 相似文献
104.
Md Abdul Quadir Varadarajan Vijayakumar Mandal Karan 《Mobile Networks and Applications》2019,24(4):1181-1197
Mobile Networks and Applications - Efficient resource identification and discovery is the primary requirements for cloud computing services, as it assists in scheduling and managing of cloud... 相似文献
105.
Robert Andreu Marina Galià Virginia Cádiz Gerard Lligadas Jose A. Reina Juan C. Ronda 《Journal of polymer science. Part A, Polymer chemistry》2013,51(23):5075-5084
3‐Phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine ( m 1 ) underwent cationic ring opening polymerization using BF3·OEt2 in alcoholic solution under mild conditions. The polymerization of m 1 proceeds through an intermediate hemiaminal ether leading mainly to the formation of polybenzoxazines with diphenylmethane bridges, and not only the classical Mannich‐type ones. During the first stages of the reaction, low‐molecular weight soluble oligomers containing benzoxazine rings are formed. At longer polymerization times, the propagation proceeds conventionally through the phenolic active sites. This polymerization mechanism is extensible to other substituted 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazines but fails in the case of 3‐alkyl‐3,4‐dihydro‐2H‐1,3‐benzoxazines or when the phenyl group in Position 3 have a substituent in the p‐position. Spectroscopic studies and kinetic experiments using model reactions and deuterium labeled benzoxazines, allow proposing a plausible different polymerization mechanism. These soluble benzoxazine‐containing polymers can be conveniently processed and impregnated on appropriate substrates before underwent crosslinking producing materials with comparable properties to those of conventional bis‐benzoxazines. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5075–5084 相似文献
106.
107.
108.
109.
Praveen VK George SJ Varghese R Vijayakumar C Ajayaghosh A 《Journal of the American Chemical Society》2006,128(23):7542-7550
Self-assembled nanotapes of a few tailor-made oligo(p-phenylenevinylene)s (OPVs) have been prepared and used as supramolecular donor scaffold to study the fluorescence resonance energy transfer (FRET) to a suitable acceptor. In nonpolar solvents, FRET occurs with nearly 63-81% efficiency, exclusively from the self-assembled OPVs to entrapped Rhodamine B, resulting in the quenching of the donor emission with concomitant formation of the acceptor emission at 625 nm. The efficiency of FRET is considerably influenced by the ability of the OPVs to form the self-assembled aggregates and hence could be controlled by structural variation of the molecules, and polarity of the solvent. Most importantly, FRET could be controlled by temperature as a result of the thermally reversible self-assembly process. The FRET efficiency was significantly enhanced (ca. 90%) in a xerogel film of the OPV1 which is dispersed with relatively less amount of the acceptor (33 mol %), when compared to that of the aggregates in dodecane gel. FRET is not efficient in polar solvents due to weak self-organization of the chromophores. These results indicate that energy transfer occurs exclusively from the self-assembled donor and not directly from the individual donor molecules. The present study illustrates that the self-assembly of chromophores facilitates temperature and solvent controlled FRET within pi-conjugated nanostructures. 相似文献
110.
M. Spontón J. C. Ronda M. Galià V. Cádiz 《Journal of polymer science. Part A, Polymer chemistry》2007,45(11):2142-2151
Phosphine oxide-containing epoxy resins were prepared from diglycidyl ether of (2,5-dihydroxyphenyl)diphenyl phosphine oxide and diglycidyl ether of bisphenol A by crosslinking with 4,4′-diaminodiphenylmethane. Several (2,5-dihydroxyphenyl)diphenyl phosphine oxide/diglycidyl ether of bisphenol A molar ratios were used to obtain materials with different phosphorus content. The properties of the thermosetting materials were evaluated by differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, and limiting oxygen index and related to the phosphorus content. Thermal and thermooxidative degradation was studied by GC/MS, 31P MAS NMR spectroscopy, and scanning electron microscopy. Limiting oxygen index values indicate good flame retardant properties that are related to the formation of a protective phosphorus-rich layer that slowed down the degradation and prevented it from being total. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2142–2151, 2007 相似文献