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51.
Michiko Shimizu Tsuguyuki Saito Yoshiharu Nishiyama Shinichiro Iwamoto Hiroyuki Yano Akira Isogai Takashi Endo 《Macromolecular rapid communications》2016,37(19):1581-1586
The dimensions of nanocelluloses are important factors in controlling their material properties. The present study reports a fast and robust method for estimating the widths of individual nanocellulose particles based on the turbidities of their water dispersions. Seven types of nanocellulose, including short and rigid cellulose nanocrystals and long and flexible cellulose nanofibers, are prepared via different processes. Their widths are calculated from the respective turbidity plots of their water dispersions, based on the theory of light scattering by thin and long particles. The turbidity‐derived widths of the seven nanocelluloses range from 2 to 10 nm, and show good correlations with the thicknesses of nanocellulose particles spread on flat mica surfaces determined using atomic force microscopy.
52.
Masahisa Wada Yoshiharu Nishiyama Giovanni Bellesia Trevor Forsyth S. Gnanakaran Paul Langan 《Cellulose (London, England)》2011,18(2):191-206
The hydrogen bond arrangement in a complex of cellulose with ammonia has been studied using neutron crystallography in combination
with molecular dynamics simulations. The O6 atom of the hydroxymethyl group is donor in a highly occupied hydrogen bond to
an ammonia molecule. This rotating ammonia molecule is donor in partially occupied and transient hydrogen bonds to the O2,
O3 and O6 atoms of the hydroxyl groups of other chains. The hydrogen atom bound to the O3 atom is disordered but it is almost
always involved in some type of hydrogen bonding. It is donated in a hydrogen bond most of the time to the O5 atom on the
same chain. However, it also rotates away from this O5 atom to be donated to an ammonia molecule part of the time. On the
other hand the hydrogen atom bound to the O2 atom is free from hydrogen bonding most of the time. It is donated in a hydrogen
bond to the O6 atom on a neighboring chain only with a relatively small probability. These results provide new insights into
how hydrogen bonds are rearranged during the conversion of cellulose I to cellulose IIII by ammonia treatment. 相似文献
53.
Saigusa D Shibuya M Jinno D Yamakoshi H Iwabuchi Y Yokosuka A Mimaki Y Naganuma A Ohizumi Y Tomioka Y Yamakuni T 《Analytical and bioanalytical chemistry》2011,400(10):3635-3641
We recently demonstrated that nobiletin, a citrus flavonoid, exhibits anti-dementia action in animals. However, no determination methods for the content of nobiletin with beneficial action in the brain of nobiletin-administered animals have been developed, nor has its pharmacokinetics been revealed completely. Here, we established the high-performance liquid chromatography/photodiode array detection method for nobiletin determination using Bond Elut C18 SPE cartridges for extraction, where the calibration curve was linear over 0.025-10 ng, with coefficient of variation of less than 6.76%. This method enabled us to determine pharmacokinetic parameters of nobiletin given intraperitoneally or per os in the brain of mice. 相似文献
54.
Hayashi M Sasano Y Nagasawa S Shibuya M Iwabuchi Y 《Chemical & pharmaceutical bulletin》2011,59(12):1570-1573
A highly active organocatalyst for alcohol oxidation has been developed. 9-Azanoradamantane N-oxyl (Nor-AZADO 4), constituting an unhindered, stable nitroxyl radical, exhibits superior catalytic activity to 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and AZADOs in the oxidation of alcohols to their corresponding carbonyl compounds. 相似文献
55.
Okada T Yamanaka K Hirose Y Goto Y Tani T Inagaki S 《Physical chemistry chemical physics : PCCP》2011,13(17):7961-7967
The excited state characteristics of phenylene (Ph)-bridged periodic mesoporous organosilica (PMO) powders with crystal-like and amorphous wall structures are investigated. Crystal-like Ph-PMO has a molecular ordering of the bridging organic moieties with intervals of 0.76 and 0.44 nm parallel and perpendicular to the mesochannel direction, respectively, whereas amorphous Ph-PMO has no molecular-level periodicity in the wall. Fluorescence from the exciton and excimer of the Ph moieties and the defect center in the silicate network were detected at room temperature, but fluorescence from the excimer and the defect center were not detected at 77 K for crystal-like Ph-PMO dispersed in a methanol/ethanol mixed solvent. The decay curve of the exciton fluorescence of crystal-like Ph-PMO at room temperature was analyzed successfully using a one-dimensional diffusion model quenched by the defect center and the excimer site. The results were discussed in comparison with those for the crystal-like biphenylene-bridged PMO reported in the preceding paper (Yamanaka et al., Phys. Chem. Chem. Phys., 2010, 12, 11688-11696). The existence of excited states with various conformations including ground state dimers or aggregates of the Ph moieties was suggested for amorphous Ph-PMO. It was clearly apparent that the differences in the excited state dynamics reflected the differences in the molecular-level structure in the wall. 相似文献
56.
57.
Yoshiharu Matsubara Toshikazu Uchida Takashi Ohnishi Koichi Kanehira Yoshiji Fujita Tsuneaki Hirashima Ikuzo Nishiguchi 《Tetrahedron letters》1985,26(37):4513-4516
Anodic oxidation in acetic acid of polycyclic cyclopropanes, namely tricyclene, cyclofenchene, and longicyclene, followed by hydrolysis brought about stereo- and regioselective formation of the corresponding homoallylic alcohols as the main product in good yields. 相似文献
58.
Masayuki Yoshikawa Yoshiharu Ikeda Hiroshi Kayakiri Kohei Takenaka Isao Kitagawa 《Tetrahedron letters》1982,23(45):4717-4720
By use of a decarboxylation reaction with lead tetraacetate and a deacetoxylation reaction with sodium borohydride as key-reactions, paromamine ( and tri-N-benzyloxycarbonylparomamine () were synthesized from D-glucosamine. 相似文献
59.
An experimental study of the damage of Si solar cells due to Q-switched ruby laser radiation has been made. Four kinds of specimen with different surface states were used in order to examine how the damage depends on the surface state: (a) chemically etched to a mirror finish, (b) mechanically polished by a 0.5 m Al2O3 powder, (c) chemically etched, but rough, (d) coated with SiO on the (c) surface. The threshold power densities, at which a change in the photo-current occurs, were for the specimens (a) to (d) respectively 60 MW cm–2, 20 MW cm–2, 30 MW cm–2 and 9 MW cm–2. Attenuations of the photo-current of the specimens, a, c and d were observed over the whole range of wavelength 500 to 1000 nm. For the b cell, however, increase of the photo-current was observed mainly in the short wavelength region. 相似文献
60.
Yoshiharu Sato Kazuaki Sugawa Michiaki Kawaguchi 《Reports on Mathematical Physics》1979,16(1):111-119
The differential geometrical consideration of the parameter space, especially as a Riemannian geometry, was initiated by C.R. Rao in 1945. This approach appears to be important for the problem of estimation and test of hypotheses as well as for applications to physical problems. It has been shown that the parameter spaces of univariate normal distribution, univariate exponential distribution and multinomial distribution are Riemannian spaces of constant curvature. In the present paper the discussion is confined to the parameter space of the two-dimensional normal distribution. It has been shown that in general the parameter space is not necessarily of a constant curvature and that, if the correlation coefficient vanishes, the parameter space becomes an Einstein space. In addition, some invariant quantities, as sectional curvature, mean curvature and scalar curvature, have been calculated. 相似文献