全文获取类型
收费全文 | 884篇 |
免费 | 29篇 |
国内免费 | 4篇 |
专业分类
化学 | 711篇 |
晶体学 | 7篇 |
力学 | 16篇 |
数学 | 37篇 |
物理学 | 146篇 |
出版年
2022年 | 6篇 |
2021年 | 9篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 20篇 |
2015年 | 16篇 |
2014年 | 18篇 |
2013年 | 41篇 |
2012年 | 31篇 |
2011年 | 53篇 |
2010年 | 33篇 |
2009年 | 26篇 |
2008年 | 63篇 |
2007年 | 80篇 |
2006年 | 60篇 |
2005年 | 85篇 |
2004年 | 58篇 |
2003年 | 54篇 |
2002年 | 48篇 |
2001年 | 10篇 |
2000年 | 18篇 |
1999年 | 14篇 |
1998年 | 5篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 11篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1942年 | 1篇 |
1938年 | 1篇 |
排序方式: 共有917条查询结果,搜索用时 15 毫秒
221.
[structure: see text] We successfully synthesized the axially substituted titanium Pc-C(60) dyad with a convenient method that improves on the traditional asymmetrical phthalocyanine routine to covalently linked phthalocyanines with other functional molecules. The intramolecular photoinduced process between phthalocyanine donor and fullerene acceptor was preliminarily studied. 相似文献
222.
Yokota Y Miyazaki A Fukui K Enoki T Hara M 《The journal of physical chemistry. B》2005,109(50):23779-23782
Electroactive tetrathiafulvalene thiol islands embedded in an n-alkanethiol SAM matrix were studied under potential control using in situ scanning tunneling microscopy. Unlike previously studied stochastic switching, the apparent height of the island could be intentionally controlled in the present system by choosing the appropriate potential and the island size. The dependence of the height change on the potential and the size is explained as structural change of the island induced by the charging effect of the electroactive moiety. 相似文献
223.
Yasuyuki Sanai Yuki Morita Youichi Asano Kenichi Ishizaki Kouzou Kubota 《Journal of polymer science. Part A, Polymer chemistry》2014,52(8):1161-1171
The structural change of the end groups of UV‐cured acrylates with time has been investigated as well as photopolymerization behavior. 2‐Ethylhexyl acrylate, n‐lauryl acrylate, 2‐(2‐ethoxyethoxy)ethyl acrylate, and 2‐ethylhexyl methacrylate were used as a monomer in the current study. In order to mimic industrial conditions, the photopolymerization was conducted with relatively high UV intensity (576 mW/cm2) using a common photoinitiator 1‐hydroxycyclohexyl phenyl ketone. Conversion‐time profile gave a linear first‐order plot suggesting that the steady state was hold throughout the polymerization. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra of the resultant polymers indicated the number of the hydroxycyclohexyl chain‐ends decreased with storage time at room temperature. Instead, a lactonic ring appeared to form at the chain‐end by transesterification of the hydroxycyclohexyl group with the ester side chain of the adjacent acrylate according to the results of mass spectrometry and 13C NMR. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1161–1171 相似文献
224.
Abstract Vermiculite and fluor-tetrasilicic mica were intercalated with alkali metals (Na, K and Rb) by vapor transport. X-ray and Raman scattering experiments were conducted to study the structure and lattice dynamics of the new clay compounds. When Rb and K atoms were intercalated to the host materials, superlattices were formed. In Na intercalated compounds, however, no superlattice x-ray diffraction peaks were found. Raman spectra exhibited drastic changes after alkali-metal intercalation, reflecting the structural changes found by our x-ray diffraction. 相似文献
225.
Ona Adomėnienė Povilas Adomėnas Antanas Gleiznys Aldona Beganskienė Lidija Poloudina Yasuyuki Gotoh 《Molecular Crystals and Liquid Crystals》2013,570(1):739-743
Abstract A synthesis of a number of 5-alkyl-2-pyrimidinol esters was conducted, their mesomorphic properties were examined. Two ring esters of said pyrimidinols are nonmesomorphic, while three ring esters are typical mesogens, forming nematic either nematic-smectic mesophases. 相似文献
226.
Yasuyuki Kagawa Noriyuki Takada Hiro Matsuda Kiyoshi Yase Moniur Halim Ifor W. Samuel 《Molecular Crystals and Liquid Crystals》2013,570(1):499-502
Abstract Photoluminescence of TCNQ-amino adducts was studied to evaluate solid state samples of photoluminescence quantum yields. High PL quantum yields suggests that TCNQ-amino adducts should be an excellent organic light emitter. Electroluminescence of TCNQ-amino adducts was demonstrated for the first time. 相似文献
227.
Kunichika Nakamiya Yasuyuki Shibata Hiroyasu Ito John S. Edmonds Masatoshi Morita 《应用有机金属化学》2005,19(2):282-286
To facilitate, by the provision of internal standards, the liquid chromatographic and mass spectrometric analysis of diphenylarsinic acid in well water and other samples related to an incident of environmental contamination in Kamisu, Ibaraki, Japan, syntheses of the analogous perdeuterated and mono‐meta‐ and di‐meta‐methylated acids were undertaken. The acids were synthesized by cleavage of the triarylarsines by sodium in liquid ammonia. The triarylarsines were made from the reaction of arsenous chloride and sodium with the appropriate aryl‐bromo compound. Properties of the compounds are given. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
228.
Takashi Katsu Tomonori Imamura Keiko Komagoe Kazufumi Masuda Tohru Mizushima 《Analytical sciences》2007,23(5):517-522
The changes induced by biologically active substances in the permeability to K+ and calcein of liposomes composed of egg phosphatidylcholine and cholesterol were measured simultaneously in order to rapidly screen the sizes of pores formed in a membrane, using different sized markers. The substances examined in the present study were classified into three types based on differences in the rates at which K+ and calcein were released. The first type released only K+, and included gramicidin A. The second type predominantly released K+, preceding the release of calcein, and included amphotericin B and nystatin. The third type, including antimicrobial peptides, such as gramicidin S, alamethicin, and melittin, and several membrane-active drugs, like celecoxib (non-steroidal anti-inflammatory drug), 1-dodecylazacycloheptan-2-one (named azone; skin permeation enhancer), and chlorpromazine (tranquilizer), caused the release of K+ and calcein simultaneously. Thus, the sizes of pores formed in a liposomal membrane increased in the following order: types one, two, and three. We determined the size more precisely by conducting an osmotic protection experiment, measuring the release of calcein in the presence of osmotic protectants of different sizes. The radii of pores formed by the second type, amphotericin B and nystatin, were 0.36 - 0.46 nm, while the radii of pores formed by the third type were much larger, 0.63 - 0.67 nm or more. The permeability changes induced by substances of the third type are discussed in connection with a transient pore formed in a lipid packing mismatch taking place during the phase transition of dipalmitoylphosphatidylcholine liposomes. 相似文献
229.
Yoshihiro Kudo Ryo Fujihara Shoichi Katsuta Yasuyuki Takeda 《Analytical sciences》2007,23(8):1003-1006
The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value. 相似文献