全文获取类型
收费全文 | 1369篇 |
免费 | 31篇 |
国内免费 | 3篇 |
专业分类
化学 | 978篇 |
晶体学 | 13篇 |
力学 | 10篇 |
数学 | 93篇 |
物理学 | 309篇 |
出版年
2023年 | 13篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 15篇 |
2019年 | 22篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 66篇 |
2012年 | 64篇 |
2011年 | 102篇 |
2010年 | 49篇 |
2009年 | 48篇 |
2008年 | 89篇 |
2007年 | 77篇 |
2006年 | 52篇 |
2005年 | 66篇 |
2004年 | 60篇 |
2003年 | 52篇 |
2002年 | 48篇 |
2001年 | 35篇 |
2000年 | 26篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1996年 | 22篇 |
1995年 | 17篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 29篇 |
1984年 | 23篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 12篇 |
1980年 | 13篇 |
1979年 | 24篇 |
1978年 | 11篇 |
1977年 | 22篇 |
1976年 | 14篇 |
1975年 | 10篇 |
1973年 | 8篇 |
1967年 | 4篇 |
排序方式: 共有1403条查询结果,搜索用时 15 毫秒
111.
Yutaka Nagasawa Ayako Watanabe Yoshito Ando Tadashi Okada 《Journal of Molecular Liquids》2001,90(1-3):295-302
We have studied femtosecond ground state recovery dynamics of phenol blue (PB) by pump-probe spectroscopy with a time resolution of 33 fs. Multiexponential decay with time constants extending from 300 fs to 10 ps were observed. Some low frequency intramolecular quantum beats were also observed. Solvent dependence of these decays and beats are discussed. 相似文献
112.
Hiroshi Tsukahara Tsuneya Ando 《Physica E: Low-dimensional Systems and Nanostructures》2005,29(3-4):614
The density of states and the conductivity are calculated in lateral superlattices with disorder in the period within a self-consistent Born approximation. Although the potential loses its periodicity on average due to disorder, it leads to an opening up of a pseudo-band-gap and modifies the conductivity perpendicular to the superlattice even qualitatively, when the energy reaches the zone boundary. 相似文献
113.
Tests were conducted to determine which horizontal reflection angles are most effective in stimulating subjective diffuseness for a listener in a room. Paired comparison tests were carried out where subjects were asked to judge in which of two sound fields they perceived more diffuseness. Results show that the most effective horizontal angle depends on the frequency of the one-third-octave-band noise, as is indicated by the interaural cross correlation. The remarkable finding in this investigation is that the scale value of subjective diffuseness may be formulated in terms of the 3/2 power of the magnitude of interaural cross correlation (IACC) and that the scale value does not vary with the frequency of the bandpass noise source. 相似文献
114.
Kazutoshi Ando 《Discrete Mathematics》2006,306(24):3181-3188
A pair (X,τ) of a finite set X and a closure operator τ:2X→2X is called a closure space. The class of closure spaces includes matroids as well as antimatroids. Associated with a closure space (X,τ), the extreme point operator ex:2X→2X is defined as ex(A)={p|p∈A,p∉τ(A-{p})}. We give characterizations of extreme point operators of closure spaces, matroids and antimatroids, respectively. 相似文献
115.
Harada T Ikeda S Hashimoto F Sakata T Ikeue K Torimoto T Matsumura M 《Langmuir : the ACS journal of surfaces and colloids》2010,26(22):17720-17725
A core-shell composite consisting of a palladium (Pd) nanoparticle and a hollow carbon shell (Pd@hmC) was employed as a catalyst for aerobic oxidation of various alcohols. The core-shell structure was synthesized by consecutive coatings of Pd nanoparticles with siliceous and carbon layers followed by removal of the intermediate siliceous layer. Structural characterizations using TEM and N(2) adsorption-desorption measurements revealed that Pd@hmC thus-obtained was composed of a Pd nanoparticle core of 3-6 nm in diameter and a hollow carbon shell with well-developed mesopore (ca. 2.5 nm in diameter) and micropore (ca. 0.4-0.8 nm in diameter) systems. When compared to some Pd-supported carbons, Pd@hmC showed a high level of catalytic activity for oxidation of benzyl alcohol into benzaldehyde using atmospheric pressure of O(2) as an oxidant. The Pd@hmC composite also exhibited a high level of catalytic activity for aerobic oxidations of other primary benzylic and allylic alcohols into corresponding aldehydes. The presence of a well-developed pore system in the lateral carbon shell enabled efficient diffusion of both substrates and products to reach the central Pd nanoparticles, leading to such high catalytic activities. This core-shell structure also provided high thermal stability of Pd nanoparticles toward coalescence and/or aggregation due to the physical isolation of each Pd nanoparticle from neighboring particles by the carbon shell: this specific property of Pd@hmC resulted in possible regeneration of catalytic activity for these aerobic oxidations by a high-temperature heat treatment of the sample recovered after catalytic reactions. 相似文献
116.
Ando K 《The Journal of chemical physics》2010,133(17):175101
Structural and energetic reorganizations in redox reaction of type 1 copper proteins are studied by density functional and ab initio molecular orbital calculations. Model complexes of the active site with varying number of ligands, from Cu(SCH(3))(0/+) to Cu(SCH(3))(Im)(2)(S(CH(3))(2))(0/+), where Im denotes imidazole, are investigated. Following the findings of structural instability in Cu(I)(SCH(3))(Im)(2) and its stabilization by the addition of the axial methionine (Met) ligand model, the structure and energetics are examined as functions of the Cu-S(Met) distance in the range of 2.1-3.3 A?. The reorganization energies in both redox states exhibit a minimum at the Cu-S(Met) distance of ~2.4?A?, whereas the ionization potential increases monotonically. The changes of reorganization energies correlate well with one of the Cu-N(His) distances rather than the Cu-S(Cys) distance. The estimated Arrhenius factor for oxidation of plastocyanin by P700(+) (in photosystem I) changes by an order of magnitude when the Cu-S(Met) distance fluctuates between 2.4 and 3.0 A?, whereas the factor for reduction of plastocyanin by cytochrome f is nearly constant. Together with the data from our previous classical molecular dynamics simulation of solvated protein, we argue that the electron transfer rate is affected, and thus may be controlled, by the fluctuation of a weakly bound axial Met ligand. We also present the assessment of various exchange-correlation functionals, including those with the long-range correction, against the CCSD(T) reference and on the basis of a perturbative adiabatic connection model. For Cu(SCH(3)) and Cu(SCH(3))(Im), simple correlations have been found between the reorganization energies and the amount of Hartree-Fock exchange. 相似文献
117.
Eiji Hashimoto Yuichi Seshimo Keita Sasanuma Yuichiro Aoki Hitoshi Kanazawa Yuji Ike Seiji Kojima 《Journal of Thermal Analysis and Calorimetry》2010,99(1):45-50
The fragility of ethylene glycol and glucose aqueous solution systems has been investigated by temperature-modulated differential
scanning calorimetry (TMDSC). The frequency and temperature dependences of complex specific heat have been observed in the
vicinity of a glass-transition temperature T
g
. It is shown that the value of the fragility index m can be determined from the temperature dependence of the α-relaxation times observed by TMDSC. We have also studied the elastic
properties of these aqueous solutions by micro-Brillouin scattering, and determined these relaxation times of elastic properties
in the gigahertz range. 相似文献
118.
Masaki Ando Sakiyo ImadzuShinya Kitagawa Hajime Ohtani 《Journal of chromatography. A》2010,1217(32):5298-5301
A particulate formation-laser scattering detector (PFLSD) was developed and used for evaluating the crystallization efficiency of inorganic polyphosphates (PPs) that reacted with either magnesium or calcium cations. As the solutions for reactive crystallization, 0.5 M ammonium buffer (pH 9.6) containing either 0.15 M MgCl2 or 0.15 M CaCl2 (MAP: magnesium ammonium phosphate and HAP: hydroxyapatite solution) were used. In the case of mono- and diphosphate (P1 and P2), the significant dependences of the particulate formation efficiency on various types of both P1/P2 and MAP/HAP reaction solutions were observed with the direct sample injection mode. The PFLSD was hyphenated with the anion-exchange chromatography and the dependence of the particulate formation efficiency on the polymerization degree (np) of PP oligomers, separated chromatographically, was evaluated sequentially. The significant suppression of the particulate formation for PP oligomers was clearly confirmed, i.e., the MAP and HAP reaction solutions did not produce the particulates of the PP oligomers having an np value of more than 3 and 5, respectively. As the overall tendency, the particulate formation efficiency in the case of the HAP solution was superior to that in the case of the MAP solution. 相似文献
119.
K. Mizuno T. Matsubara K. Sugahara M. Ichida H. Ando T. Itoh 《Journal of luminescence》2011,131(3):506-509
A persistent hole-burning is observed in β-perylene microcrystallites, which were embedded in poly-vinyl alcohol. By laser light excitation at 22,535 cm−1 and at 10 K, the hole is found at the excitation photon energy. The mechanism of the persistent hole-burning is interpreted in terms of the resolution of microcrystallites into smaller microcrystallites. This is a novel observation of the persistent hole-burning in aromatic microcrystallites. When the specimen, which includes a hole, is annealed at high temperatures, the resolved microcrystallites restore back to the old position as had been. The β-perylene microcrystallite specimen that we have grown was as small as 1.5 nm in average diameter. They are one order smaller in number of molecules included, compared to those that have been reported on aromatic microcrystallites, anthracene for example. Due to this, we were able to observe the 0-0 transition energy, which varied according as the number of molecules involved in the microcrystallites. We also observed the 0-0 absorption (excitation) spectrum, which depends on the molecular arrays in the microcrystallites. The 0-0 transition of a single molecule in poly-vinyl alcohol matrix is anticipated to be located at 22,885 cm−1. 相似文献
120.
Mizukami S Wu F Sakuma A Walowski J Watanabe D Kubota T Zhang X Naganuma H Oogane M Ando Y Miyazaki T 《Physical review letters》2011,106(11):117201
Spin precession with frequencies up to 280 GHz is observed in Mn(3-δ)Ga alloy films with a perpendicular magnetic anisotropy constant K(u)~15 M?erg/cm(3). The damping constant α, characterizing macroscopic spin relaxation and being a key factor in spin-transfer-torque systems, is not larger than 0.008 (0.015) for the δ=1.46 (0.88) film. Those are about one-tenth of α values for known materials with large K(u). First-principles calculations well describe both low α and large K(u) for these alloys. 相似文献