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排序方式: 共有91条查询结果,搜索用时 15 毫秒
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S. B. Halligudi K. N. Bhatt K. Venkatasubramanian 《Reaction Kinetics and Catalysis Letters》1993,51(2):459-464
Investigations on the catalytic activity of a transient Rh(I) triphenylphosphine complex1 anchored on montmorillonite clay have been carried out with respect to hydroformylation of olefins at 70°C and 60 atm of CO+H2 (1:1). The analysis has shown that aldehydes and hydrocarbons of the corresponding olefins result under hydroformylation conditions. In limonene, reaction proceeds with double hydroformylation and hydrogenation to give the respective oxo products. The catalytic activities of1 are compared with Wilkinson's RhI (H) (CO) (PPh3)2 (6) complex in solution under the same hydroformylation conditions. 相似文献
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M Bárány D G Spigos E Mok P N Venkatasubramanian A C Wilbur B G Langer 《Magnetic resonance imaging》1987,5(5):393-398
Water-suppressed and slice-selective proton spectra of live human brain exhibited several resonances that were tentatively assigned to metabolites such as N-acetylaspartate, glutamate, phosphocreatine and creatine, choline derivatives, and taurine. In the liver spectrum of a healthy volunteer, the major resonance was tentatively assigned to a fatty acyl methylene and the minor resonances to protons in carnitine, taurine, glutamate, and glutamine. In the spectrum of a cancerous liver, resonances in addition to those present in the normal liver were seen. Protein degradation in the liver with cancer was indicated by resonances from urea and from the ring protons in tryptophan, tyrosine, and phenylalanine. Furthermore, increased nucleic acid synthesis was indicated by resonances from nucleotide protons. 相似文献
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4-Hydroxybenzocyclobutene was prepared in good yield from the demethylation of 4-methoxybenzocyclobutene with aluminum iodide in acetonitrile. 相似文献
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Loon-seng Tan N. Venkatasubramanian 《Journal of polymer science. Part A, Polymer chemistry》1996,34(17):3539-3549
A series of novel benzocyclobutene (BCB)-pendanted polyamides (inherent viscosities: 0.20–0.69 dL/g) was synthesized from 3,5-diaminophenyl-4-benzocyclobutenyl ketone, and terephthaloyl, isophthaloyl, 4,4′-oxydibenzoyl chlorides, as well as 4,4′-(o-phenylenedioxy)dibenzoyl chloride. The DSC studies demonstrated that the BCB crosslinking exothermic transition occurred at nearly the same temperature (max. ∼︁ 275°C) for all the four polyamides, and they were thermally stable up to 380°C in helium, where the weight loss started to occur. TGA and DSC studies in air indicated that the polymers, in contrast to the model compound, showed evidence of oxidation just prior to or occurring simultaneously with the BCB crosslinking reaction. This could be attributed to the oxidation of the reactive diene generated from the ring-opening of the BCB competing with the process of two BCB pendant units approaching each other for crosslinking reaction. Preliminary examination of the BCB-pendanted polyamide regenerated from a methanesulfonic acid solution indicates that the BCB ring is quite stable (DSC evidence) in the strong acid medium. © 1996 John Wiley & Sons, Inc. 相似文献
7.
The kinetics of reaction between benzyl chloride and phenol (or substituted phenols) in the presence of sodium hydroxide have
been investigated. A differential application of the effect of substituents on the reaction rate to distinguish between a
rate-limiting oxygen or carbon attack has been attempted. Considerable scatter in the Hammett plot for the latter attack points
to an essentially O-alkylation. The rate constants correlate well with pKa values of the different phenols. The influence of salt and solvent on the reaction rate suggests this reaction to be an ion-dipole
one. 相似文献
8.
P.W. Finn L.E. Kavraki J.-C. Latombe R. Motwani C. Shelton S. Venkatasubramanian A. Yao 《Computational Geometry》1998,10(4):263-272
This paper describes a randomized approach for finding invariants in a set of flexible and chemically distinct ligands (drug molecules) that underlies an integrated software system called RAPID currently under development. An invariant is a collection of features embedded in
3 which is present in one or more of the possible low-energy conformations of each ligand. Such invariants are called pharmacophores and contain the parts of the ligand that are primarily responsible for its binding with a receptor. The identification of pharmacophores is crucial in drug design since frequently the structure of targeted receptor is unknown but a number of molecules that interact with it have been discovered by experiments. In these cases the pharmacophore is used as a template for building more effective drugs. It is expected that our techniques and results will prove useful in other applications such as molecular database screening and comparative molecular field analysis. 相似文献
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