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31.
Cavity cluster approach for quantification of cavitational intensity in sonochemical reactors 总被引:2,自引:0,他引:2
The mechanism involved in the spectacular effects from cavitation phenomenon is very complex and there have been several proposed theories to explain the observed results. The experimental as well as the visual observations indicate that a single collapsing cavity is also influenced by the dynamics of the surrounding cavities, which are very near to the collapsing cavity. The observed effects and erosion patterns cannot be explained properly on the basis of a single cavity collapse and hence in this study a cavity cluster (group of cavities) has been considered to understand the mechanism of cavitational effects. The effect of intensity, frequency of ultrasound, initial size of the cluster and the fraction of energy transferred from the collapsing cavities to the surrounding cavities on the cavitational intensity quantified in terms of the pressure pulse generated at the collapse of cavities as well as the active zone of cavitation has been investigated using bubble/cavity dynamics equations, numerically. On the basis of the trends obtained, empirical correlations estimating the collapse pressure and active volume of cavitation, have been developed. 相似文献
32.
33.
Trinh An Huy Rameshwar Adhikari Thomas Lüpke Sven Henning Goerg H. Michler 《Journal of Polymer Science.Polymer Physics》2004,42(24):4478-4488
The orientation behavior of isotactic polypropylene (iPP) in α‐ and β‐crystal form was investigated by rheo‐optical Fourier transformed infrared (FTIR) spectroscopy. This method enabled quantification of the degree of orientation as a feature of structural changes during uniaxial elongation in not only the crystalline phase but also the amorphous one. Molecular orientation mechanisms can be successfully derived from experimental results. Generally, three mechanisms were detected for iPP: (1) interlamellar separation in the amorphous phase, (2) interlamellar slip and lamellar twisting at small elongations, and (3) intralamellar slip at high elongations. The third mechanism was favored by α‐PP, whereas β‐PP favored the second mechanism, which, in fact, was responsible for the different mechanical properties of both materials at the macroscopic level. On the other hand, crystallization conditions may have significantly affected the amorphous orientation. Nevertheless, for both iPP types the chains in the amorphous phase always oriented less than did those in the crystalline phase. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4478–4488, 2004 相似文献
34.
Anwar Usman Ibrahim Abdul Razak Suchada Chantrapromma Hoong-Kun Fun Jayanta Kumar Ray Sujit Das Adhikari Bishnu Pada Datta 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1441-1442
In the title compound, C20H20FNO5S, the pyrrolidine ring adopts an envelope conformation. The fluorophenyl and thiophene rings are individually planar. The molecular and crystal structures are stabilized by intra- and intermolecular C—H⋯O interactions. 相似文献
35.
36.
Medha Rele B. S. Patro S. Adhikari G. P. Kalena S. Chattopadhyay T. Mukherjee 《Journal of Chemical Sciences》2002,114(6):739-747
The free radical scavenging properties and possible antioxidant activity of 1,3-diphenylpropane-1,3-dione (1) are reported.
Pulse radiolysis technique was employed to study the one-electron oxidation of 1 with various radicals viz. CCl3O2
•, N3
• and•OH in homogeneous aqueous solution. All these radicals reacted with 1 under ambient conditions at almost diffusion controlled
rates producing transient species with an absorption maximum around 420 nm that decayed at first order rates. The transient
absorption peak was shifted in the case of CCl3OO• radical reaction with 1 due to change in the polarity of the medium. Formation of a stable product with a broad absorption
band starting from 400 nm and cut off at 230 nm was observed in the oxidation of 1 with•OH and•N3 radicals. In a biological system also, 1 showed significant inhibitory activity against Fe2+-mediatedlipidperoxidation. Based on these observations, a suitable mechanism for the oxidation of 1 has been proposed. 相似文献
37.
38.
Aniruddha Das 《合成通讯》2017,47(23):2254-2267
Investigation into Sonogashira reaction on 5-iodo-1-(phenyl/p-halophenyl)imidazole-4-carbonitrile compounds had been developed by introducing an iodo atom at the C-5 position of the imidazole ring of 5-amino-1-(phenyl/p-halophenyl)imidazole-4-carbonitrile compounds. Specifically, 5-iodo-1-(4-iodophenyl)imidazole-4-carbonitrile compound had shown double Sonogashira coupling reactions with two differently substituted iodine along with the formation of two other compounds where an unusual coupling product with self-aggregation property was obtained. In other cases, monocoupling had been observed together with another compound where iodine atom present at C5 position of imidazole was replaced by hydrogen atom. 相似文献
39.
A calix[5]arene-based solvent extraction reagent displaying very high selectivity for lead has been prepared, one molecule of which extracts two lead ions in a stepwise manner. The first Pb2+ ion is bound to five phenoxy oxygen atoms inside the calixarene cavity due to which the ligand undergoes conformational freezing in stable cone conformer. This causes positive allosteric effect for co-extraction of the second lead ion due to the aggregation of functional groups. 相似文献
40.
A. Das D. Mukhopadhyay S. Adhikari M. Baer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,65(3):373-381
In this article are presented the first ever derived single-valued
diabatic potentials for the reactive H2 + F system based on a
rigorous study of the conical intersection (ci) and
Born-Oppenheimer non-adiabatic coupling terms (BO NACTs). This study revealed the
existence of a Jahn-Teller (1, 2) ci located at a point on the collinear
axis and a Renner-Teller (2, 3) ci along this axis. The diabatic
potentials were calculated employing the rigorous adiabatic-to-diabatic transformation
(ADT) angles (also known as mixing angles) which possess integer Berry
phases along any closed contour at the region of interest in configuration space. The ADT
angles were calculated employing BO NACTs and line integrals. 相似文献