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171.
Yuko?Ogihara Richard?L.?SmithJr.Email author Hiroshi?Inomata Kunio?Arai 《Cellulose (London, England)》2005,12(6):595-606
Direct observations of the heating of microcrystalline cellulose (230 DP) in water at temperatures up to 410 °C and at pressures
up to 700 MPa were made with a batch-type microreactor. Cellulose particles were found to dissolve with water over temperatures
ranging from 315 to 355 °C at high pressures. Dissolution temperatures depended on water density and decreased from about
350 °C at a water density of 560 kg/m3 to a minimum of around 320 °C at a water density of 850 kg/m3. At densities greater than 850 kg/m3, the dissolution temperatures increased and reached a value of about 347 °C at 980 kg/m3. The cellulose dissolution temperatures were independent of heating rates for values ranging from 10 to 17 °C/s. The low
dependence of dissolution temperatures on the heating rates is strong evidence for simultaneous dissolution and reaction of
the cellulose. Different phenomena occurred depending on water density. At low densities, particles turned transparent and
seemed to dissolve into the aqueous phase from the surface. From 670 to 850 kg/m3, the cellulose particles visibly swelled just before completely collapsing and dissolving into the aqueous phase. The swelling
probably increased water accessibility and particle surface area and thus lead to the lower dissolution temperatures observed.
From 850 to 1000 kg/m3, the particles required longer times to dissolve and many fine brown-like particles were generated as the particles dissolved.
FT-IR spectra of the residues were analyzed. Residues formed from heating cellulose at high densities still retained some
cellulose character whereas those as low densities had little cellulose character, especially in the O–H stretching vibration
region. 相似文献
172.
173.
A globally and superlinearly convergent primal-dual interior point trust region method for large scale constrained optimization 总被引:1,自引:0,他引:1
This paper proposes a primal-dual interior point method for solving large scale nonlinearly constrained optimization problems. To solve large scale problems, we use a trust region method that uses second derivatives of functions for minimizing the barrier-penalty function instead of line search strategies. Global convergence of the proposed method is proved under suitable assumptions. By carefully controlling parameters in the algorithm, superlinear convergence of the iteration is also proved. A nonmonotone strategy is adopted to avoid the Maratos effect as in the nonmonotone SQP method by Yamashita and Yabe. The method is implemented and tested with a variety of problems given by Hock and Schittkowskis book and by CUTE. The results of our numerical experiment show that the given method is efficient for solving large scale nonlinearly constrained optimization problems.Acknowledgement The authors would like to thank anonymous referees for their valuable comments to improve the paper. 相似文献
174.
This paper summarizes some hitherto unpublished findings on factors affecting or resulting from social mobility, based on
data obtained from the Social Stratification and Social Mobility Survey conducted in 1955 by the Research Committee of the
Japan Sociological Society.1) Section I is concerned with factors related to inter-generation occupational mobility, Section II with inter-generation educational
mobility, and Section III with occupational mobility within the individual’s lifetime. In additon, in Section IV relations
between social mobility and respondent’s attitudes will be dealt with. 相似文献
175.
We report on the absorption spectra of amorphous Mn2+ aluminosilicates which may be considered as insulating spin glasses at low temperature. The two bands localized around 4 180 Å and 3 550 Å were assigned respectively to the 6A1 → 4Ea, 4A1 (4G) and 6A1 → 4Eb(4D) electric dipole exchange transitions. The temperature dependence of their intensity and position are related to the static two spin correlation functions of nearest ions. This gives informations on the magnetic ordering in such a spin glass. 相似文献
176.
Yoshimasa Hirata Hisao Nakata Kiyoyuki Yamada Kunio Okuhara Takayuki Naito 《Tetrahedron》1961,14(3-4):252-274
The structure of aureothin, the third nitro compound obtained from nature, has been elucidated as I. Several reactions of aureothin and its derivatives are described. 相似文献
177.
A structure of the sex pheromone produced by the female cigarette beetle (Lasioderma serricorne F.) is established as 4,6-dimethyl-7-hydroxy-nonan-3-one (Ia) by chemical and spectroscopic evidences. 相似文献
178.
Highly dilute mixtures of 1,3-butadiene and 1,3-butadiene-1,1,4,4-d4 were pyrolyzed behind reflected and incident shock waves, respectively. Concentrations of H and D atoms were measured by resonance absorption spectroscopy. In the early stages of the reaction, nearly equal amounts of H and D were formed from CD2CHCHCD2, indicating that loss of H from C2 followed by loss of D from C1 is a more important reaction than breaking of the central C? C bond. Overall, rate constants for atom-forming reactions are much slower than rate constants for disappearance of butadiene in earlier experiments, suggesting that most of the butadiene disappears by processes that do not involve H or D atoms or by radicals that produce them rapidly. 相似文献
179.
180.
A small column packed with immobilized bovine carbonic anhydrase is used for determination of traces of zinc in aqueous solution, based on the measurement of recovered esterase activity of the metal-free apoenzyme after taking up zinc from the sample solution. Conditions for the removal of zinc from the immobilized enzyme and for activity measurement are established. A linear calibration graph is obtained between 1 × 10?8 and 4 × 10?7 g of zinc. Then the method is successfully applied to the determination of zinc in tea, sediment and spring water. 相似文献