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1.
Indrajit Kar B. M. Mandal S. R. Palit 《Journal of polymer science. Part A, Polymer chemistry》1969,7(10):2829-2836
Chain transfer constants of some fluoroalcohols [HCF2(CF2)n?1CH2OH, n = 2, 4, 6] in the catalyzed polymerization of vinyl acetate, styrene, acrylonitrile, and methyl methacrylate at 60°C have been evaluated by a method based on degree of polymerization. Since fluoroalcohols are normally nonsolvents for polymers, a homogeneous reaction phase is maintained by carrying out the polymerization in benzene (except in case of acrylonitrile, where no solvent was used). The transfer constants vary, depending on the reactivity as well as the polarity of the radicals, in the following order: vinyl acetate > styrene > methyl methacrylate > acrylonitrile. Of the three fluoroalcohols studied, the transfer constants increase with the increasing value of n. The results have been interpreted in terms of polar structure contribution in the transition state of the transfer reactions. 相似文献
2.
Shefali Saxena M. Palit Purnanand S. K. Raza 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):247-253
Abstract A series of structurally related unsymmetrically substituted methylphosphonate diesters have been synthesised and subjected to electron impact (El) mass spectral studies. These studies though aimed at total identification of the compounds, resulted in certain interesting observations and hence are being reported. In order to confirm the observations under electron impact and to support the mechanism of fragmentation we have also performed MSNS experiments in both daughter ion and parent ion modes. 相似文献
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4.
B. B. Palit 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1980,31(3):384-399
Zusammenfassung In der vorliegenden Arbeit werden elektrische Maschinen, im Hinblick auf die Dichte und den Fluss elektromagnetischer Energie im Luftspaltraum, einheitlich untersucht. Der Grund für derartige Untersuchungen ist, die elektrischen Maschinen als physikalische Gebilde mit Strombelägen, Durchflutungen, elektrischen und magnetischen Feldern zu, betrachten und dementsprechend zu analysieren. Anschliessend sind die aus solchen Analysen erhaltenen Ergebnisse mit denjenigen, bereits bekannten, Ergebnissen zu vergleichen, die sich bei der Betrachtung der elektrischen Maschinen als Netzwerke aus Widerständen, Induktivitäten, Gegeninduktivitäten und Rotationsinduktivitäten ergeben. Um die Analyse systematisch durchführen zu können, wird zunächst eine allgemeine Theorie entwickelt, die der Gegenstand dieses Aufsatzes ist. Mit dieser Theorie werden in einem zweiten Aufsatz verschiedene elektrische Maschinen einheitlich untersucht.
Dieser Aufsatz ist ein stark gekürzter Auszug aus der gleichnamigen Habilitationsschrift des Autors. 相似文献
Summary In this treatise a unified analysis of electrical machines has been presented with respect to the density and the flow of electromagnetic energy in the air-gap space. The reason for such an analysis is to investigate the physical aspects of electrical machines based on current sheets, magnetomotive forces and electric and magnetic fields. The results of such kind of investigations are to be compared with the results obtained by considering the electrical machines as networks having circuit-elements like resistances, inductances, mutual inductances and rotational inductances. For a systematic investigation it is necessary to develop a general theory first, which is, as a matter of fact, the topic of this paper. A unified analysis of several electrical machines by applying the general theory is the theme of a subsequent paper.
Dieser Aufsatz ist ein stark gekürzter Auszug aus der gleichnamigen Habilitationsschrift des Autors. 相似文献
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Ajit Kumar Chaudhuri Santi R. Palit 《Journal of polymer science. Part A, Polymer chemistry》1968,6(8):2187-2196
The mode of termination in the vinyl acetate–isobutyl methacrylate (VA–IBMA) and methyl methacrylate–methyl acrylate (MMA–MA) copolymerization systems has been investigated at 60°C. by using the dye-interaction technique for functional endgroup estimation. The results show that pairs of poly(vinyl acetate) radicals interact almost exclusively through a disproportionation mechanism. In the homopolymerization of methyl methacrylate and methyl acrylate, about 1.16 and 1.22 carboxyl-containing endgroups per polymer molecule have been estimated, which shows the predominance of disproportionation over combination in these termination reactions. In poly(isobutyl methacrylate) about 1.55 tagged initiator fragments per chain indicate that 29% of the total radicals terminate through the disproportionation mechanism. Cross termination in the (VA–IBMA) copolymerization system occurs almost entirely through combination for monomer feeds richer in isobutyl methacrylate content while for the MMA–MA system, combination is more important at intermediate monomer feed ratios. These results have been discussed in the light of different explanations for the reaction mechanism. 相似文献
7.
Ramakrishna G Jose DA Kumar DK Das A Palit DK Ghosh HN 《The journal of physical chemistry. B》2006,110(20):10197-10203
Femtosecond transient absorption spectroscopy has been employed to understand the excited state dynamics of [Ru(bpy)(2)Sq](+) (I; bpy is 2,2'-bipyridyl, and Sq is the deprotonated species of the semiquinone form of 1,2-dihydroxy benzene) and its derivatives, a widely studied near-infrared (NIR) active electrochromic dye. Apart from the well-defined dpi(Ru) --> pi(bpy)-based metal-to-ligand charge transfer (MLCT) transition bands at approximately 480 nm, this class of molecules generally shows another dpi(Ru) --> pi(Sq)(SOMO)-based intense MLCT band at around 900 nm, which is known to be redox active and bleaches reversibly upon a change in the oxidation state of the coordinated dioxolene moiety. To have better insight into the photoinduced electron transfer dynamics associated with this MLCT transition, detailed investigations have been carried out on exciting this MLCT band at 800 nm. Immediately after photoexcitation, bleach at 900 nm has been observed, whose recovery is found to follow a triexponential function with major contribution from the ultrafast component. This ultrafast component of approximately 220 fs has been ascribed to the S(1) to S(0) internal conversion process. In addition to the bleach, we have detected two transient species absorbing at 730 and 1000 nm with a formation time approximately 220 fs for both species. The excited state lifetimes for these two transient species have been measured to be 1.5 and 11 ps and have been attributed to excited singlet ((1)MLCT) and triplet ((3)MLCT) states, respectively. Transient measurements carried out on the different but analogous derivatives (II and III) have also shown similar recovery dynamics except that the rate for the internal conversion process has increased with the decrease in the S(1) to S(0) energy gap. The observed results are consistent with the energy gap law for nonradiative decay from S(1) to S(0). 相似文献
8.
Santi R. Palit F.A.Sc. 《Proceedings Mathematical Sciences》1977,85(2):68-70
Dissolved nitrogen is reduced to ammonia at a platinum cathode enclosed in a cellophane membrane and is oxidised to nitric acid at a similarly enclosed anode at very low current density (~1 mA/cm2), the electrolyte being distilled water. This is attributed to highly active reducing and oxidising species formed near the cathode and anode respectively under such low-current low-concentration condition of electrolysis. 相似文献
9.
Polyethylene, normally soluble at an elevated temperature in some single solvents, is found to be soluble in the following binary mixtures of nonsolvents at a much lower temperature, (often in the vicinity of room temperature): xylene–carbon disulfide, cyclohexane–carbon disulfide, cyclohexane–trichloroethylene, and cyclohexane–cyclohexanone. The fractionated polymer samples show a maximum in [η] values at the optimum solvent compositions corresponding to a minimum in cloud temperature Te. The results are discussed with respect to the current theories on solubility. The optimum solvent composition agrees with the prediction of a newly developed theoretical equation in two of the above four mixtures. 相似文献
10.
Mandira Sinha H. Majumdar P. Basu Subinit Roy R. Bhattacharya M. Biswas M. K. Pradhan R. Palit I. Mazumdar S. Kailas 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):403-410
Fusion excitation functions are measured for the system 6Li + 28Si using the characteristic $ \gamma$ -ray method, encompassing both the sub-barrier and above-barrier regions, viz, E lab = 7-24 MeV. Two separate experiments were performed, one for the above-barrier region ( E lab = 11-24 MeV) and another for the below-barrier region ( E lab = 7-10 MeV). The results were compared with our previously measured fusion cross-section for the 7Li + 28Si system. We observed the enhancement of the fusion cross-section at sub-barrier regions for both 6Li and 7Li , but the yield was substantially larger for 6Li . However, for well-above-barrier regions, a similar type of suppression was identified for both the systems. 相似文献