全文获取类型
收费全文 | 336篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 245篇 |
晶体学 | 6篇 |
力学 | 15篇 |
数学 | 10篇 |
物理学 | 67篇 |
出版年
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 30篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 27篇 |
2007年 | 28篇 |
2006年 | 16篇 |
2005年 | 17篇 |
2004年 | 24篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有343条查询结果,搜索用时 15 毫秒
331.
Triplet superconductors such as Sr2RuO4 and NaxCoO2·yH2O are now found to be p-wave (px±ipy) or f-wave ((px±ipy)coscpz) superconductors. In conventional singlet superconductors, vortices are quantized because phase of order parameter must rotate by 2π around a vortex. But triplet superconductors have a degree of freedom of spin, which is described by d-vector. The d-vector and phase can rotate by π around a vortex, separately. Therefore appearance of HQVs is predicted. Theoretically, it is found that a pair of HQVs is more stable than a singly quantized vortex, for several parameter regions.In this study, in order to investigate quasi-particle bound states around two vortices in s-wave superconductors, we have developed a new numerical method to solve the BdG equation for two vortices state, using Mathieu functions. We confirmed the validity of this method for two vortices state and applied it in case of a pair of vortices. And we solved it. 相似文献
332.
Abstract Okinaga et al.1 have recently reported a novel trisaccharide obtained from the acrosome reaction-inducing substance (ARIS) of the starfish Asterias amurensis. The ARIS is essential for triggering the acrosome reaction in homologous spermatozoa, and the biological activity is due to the sugar moiety. The trisaccharide, composed of xylose (Xyl), galactose (Gal), and fucose (Fuc), and proposed to have a sequence of Xyll→3Gall→3 or 4[4 or 3-(So3 ?)]Fuc, was deduced to be one of the major structural units constructing the side chain of the high molecular carbohydrate portion of the ARIS. The sequence differs from similar oligosaccharides, found in hemicellulose2 and composed of d-xylose, d-galactose, and l-fucose. The ARIS contains a unique saccharide chain having sulfated l-fucose as an internal residue. This unique structure prompted us to synthesize the trisaccharide as well as to reveal the anomeric configuration of Xyl and Gal moieties and the sulfated position of Fuc residue. 相似文献
333.
Nobuko Mibu Hatsumi Aki Hirohito Ikeda Ai Saito Wataru Uchida Kazumi Yokomizo Jianrong Zhou Takeshi Miyata Kunihiro Sumoto 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1015-1018
Carbohydrate recognition of some bioactive symmetrical tripodal receptor type tris(2-aminoethyl)amine (TAEA) derivatives was investigated. In calorimetric experiments, the highest binding constant (Ka) of compound C (C35H49N5O4S) with methyl α-d-mannopyranoside was Ka = 858 M?1 with 1:1 stoichiometry. Formation of hydrogen bonds in binding between symmetrical tripodal receptor type compound C and sugars was suggested by the large negative values of ?H° (=?34 to ?511 kJ mol?1). In a comparison of each set of α- and β-anomers of some monosaccharides (methyl α/β-d-galactopyranoside, methyl α/β-d-glucopyranoside, and methyl α/β-l-fucopyranoside), compound C showed that the binding constant of β-anomer was larger than that of the corresponding α-anomer, indicating higher β-anomer selectivity. The calculated energy-minimized structure of the complex of compound C with guest methyl α-d-mannopyranoside is also presented. The experimental results obtained from this work indicated that symmetrical tripodal receptor type TAEA derivative C has a lectin-like carbohydrate recognition property. 相似文献
334.
For investigating the effects of chemical stimulation to cultured cells, we have developed a quartz crystal sensor system with a micro charge-coupled device (CCD) camera that enables microphotograph imaging simultaneously with quartz crystal measurement. Human hepatoma cell line (HepG2) cells were cultured on the quartz crystal through a collagen film. The electrode of the quartz crystal was made of indium tin oxide (ITO) transparent electrodes that enable to obtain a transparent mode photograph. Glutaraldehyde and trypsin were injected to the chamber of the cells, respectively. The response of the quartz crystal was monitored and microphotographs were recorded, and the resonance frequency and resonance resistance were analyzed with an F-R diagram that plotted the resonance frequency and resonance resistance. In the case of the glutaraldehyde injection, the cells responded in two steps that included the fast response of the cross-linking reaction and the successive internal change in the cells. In the case of the trypsin injection, the responses included two processes. In the first step, cell adhesion factors were cleaved and the cell structure became round, and in the next step, the cells were deposited on the quartz crystal surface and the surface of the cells was directly in contact with the quartz crystal surface. 相似文献
335.
A coprecipitation method using calcium tungstate was developed to remove 87Sr isobaric interference with 87Rb prior to measurement of Rb by ID-ICP-MS. Precipitation of calcium tungstate was obtained by adding Ca(NO3)2 solution and (NH4)2WO4 solution to the sample, where (NH4)2WO4 was added more than the stoichiometric proportion to precipitate Ca(NO3)2 completely and remove Sr effectively. Furthermore, in order to reduce matrix burden to the ICP-MS instrument, the residual (NH4)2WO4 was removed by adding conc. HNO3. Prior to the application, thorough purification of coprecipitant reagent was carried out to reduce the blank. The effectiveness of the present method was verified by analyzing two brown rice flour certified reference materials (CRMs), NIES CRM 10a and NIES CRM 10b. Finally, the present method was applied to the measurement of Rb in a white rice flour RM sample being developed by National Institute of Metrology of Japan. 相似文献
336.
Fukunaga H Fedorov DG Chiba M Nii K Kitaura K 《The journal of physical chemistry. A》2008,112(43):10887-10894
Quinacridones (QAs) are organic hydrogen-bonded pigments, which are yellow in solution and become reddish to violet in solid phase depending on the crystal structure. We have carried out regular and fragment molecular orbital (FMO) based time-dependent density functional theory (TDDFT) calculations of the alpha (I), beta, and gamma crystalline phases of QA to examine the origin of the spectral shift in the solid phase. On the basis of the TDDFT calculations, we have found that the spectral shift from gas to solid phase in QA is dominated by the interplay of the structural deformation, electrostatic potential (crystal field), and intermolecular interactions, and each contribution is of the same order of magnitude. The spectral shift induced by the structural deformation is mainly caused by the stretch of the CO bond. The individual intermolecular interactions contribute to bathochromic and hypsochromic shifts depending on the spatial orientation, and their sums result in the bathochromic shift overall. 相似文献
337.
338.
Two new mycolactones, mycolactones S1 and S2, were isolated from culture agar of Mycobacterium ulcerans subsp. shinshuense. Their structures were established in a three-step procedure: (1) probable structures were speculated from MS analysis; (2) candidates were synthesized; (3) HPLC profiles were established for identification of the natural products. Newly isolated mycolactones correspond to the "oxidized forms" of mycolactone A/B, the causative toxin of Buruli ulcer, isolated from Mycobacterium ulcerans. 相似文献
339.
Le Bris R Tsunobuchi Y Mathonière C Tokoro H Ohkoshi S Ould-Moussa N Molnar G Bousseksou A Létard JF 《Inorganic chemistry》2012,51(5):2852-2859
The study of the metastable states, obtained by thermal quenching or by light irradiation in the [{Co(prm)(2)}(2){Co(H(2)O)(2)}{W(CN)(8)}(2)]·4H(2)O complex, is reported using powder X-ray diffraction, Raman spectroscopy, optical reflectivity, and magnetic measurements. This compound is characterized by a electron-transfer (ET) phase transition occurring between a high-temperature phase (HT phase) formed by paramagnetic Co(II)-W(V) units and a low-temperature phase (LT phase) formed by diamagnetic Co(III)-W(IV) units. Metastable phases can be induced at low temperature either by thermal quenching rapidly cooling phase named RC or by irradiation photo-induced phase named PI similar to the well-known Light-Induced Excited Spin State Trapping effect. The relaxation dynamics of the metastable phases have been studied and revealed some differences between the RC and PI phases. The sigmoidal shape of the relaxation curves in the RC phase is in agreement with the cooperative nature of the process. Thermodynamic parameters that govern the relaxation have been determined and used to reproduce the experimental Thermal-Induced Excited Spin State Trapping curve. 相似文献
340.
Takahiro Hamada Eiji Fujii Dewei Chu Kazumi Kato Yoshitake Masuda 《Journal of Crystal Growth》2011,314(1):180-184
Morphological change from ZnO films to ZnO prisms is achieved by an electrochemical deposition method on a graphite substrate at the low temperature of 70 °C. The ZnO prisms, which are prism-shaped ZnO rods with a wide diameter, have hexagonal well-defined crystallographic facets. The ZnO prism is 1.4 μm in diameter and 1.3 μm in length. Transmission electron microscopy and electron diffraction patterns indicate that the ZnO prisms have a single-crystalline wurtzite structure with c-axis orientation. Additionally, cathodoluminescence shows that the annealed ZnO prisms in nitrogen gas emit a significant level of near-band-edge ultraviolet light. 相似文献