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51.
Bartoli G Bosco M Carlone A Locatelli M Massaccesi M Melchiorre P Sambri L 《Organic letters》2004,6(13):2173-2176
[reaction: see text] The first asymmetric aminolysis of trans-aromatic epoxides with anilines is described. The process affords enantioenriched anti-beta-amino alcohols in up to 99% ee. The complete regio- and diastereoselectivity observed uses commercially available [Cr(Salen)Cl] as a Lewis acid catalyst and in combination with a very simple experimental procedure renders the present reaction a facile and practical tool for the synthesis of chiral nonracemic anti-beta-amino alcohols. 相似文献
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We provide some new families of permutation polynomials of \({\mathbb {F}}_{q^{2n}}\) of the type \(x^rg(x^{s})\), where the integers r, s and the polynomial \(g \in {\mathbb {F}}_q[x]\) satisfy particular restrictions. Some generalizations of known permutation binomials and trinomials that involve a sort of symmetric polynomials are given. Other constructions are based on the study of algebraic curves associated to certain polynomials. In particular we generalize families of permutation polynomials constructed by Gupta–Sharma, Li–Helleseth, Li–Qu–Li–Fu. 相似文献
56.
We describe an interferometer that makes use of an optical pickup. This widespread consumer electronics component has a high degree of technological content. A typical head contains a remarkable, highly integrated sample of optoelectronic laboratory equipment. The application that we report is a significant and novel example of the potential exploitation of the unique features of such a device for scientific aims. Many interferometric configurations can be envisaged, depending on the specific pickup design. We present a Fizeau multiphase homodyne interferometer that makes use of an astigmatic-focus-detection pickup. Its quadrant detector provides four photocurrent signals whose phase delays can be easily controlled. This allows us to apply phase-shifting interferometry algorithms for data reduction. 相似文献
57.
H Fillion M Porte M H Bartoli Z Bouaziz M Berlion J Villard 《Chemical & pharmaceutical bulletin》1991,39(2):493-495
Mannich bases of 5-hydroxynaphthalene-1,8-carbolactone 1 were prepared from various secondary amines or bulky primary amines and formaldehyde. They were isolated in almost all cases as hydrochlorides. These derivatives were submitted to in vitro antifungal and cytotoxic assays. The antifungal assays were performed against three strains of yeasts and five strains of human pathogenic fungi. Two of the tested compounds, 2i and 2j, exhibited interesting antifungal activities against Candida albicans and Candida tropicalis. The cytotoxic activity was evaluated towards L 1210 leukemia cells. Almost all of the Mannich bases had shown significant activity against this tumor cell line as values of IC50 less than or equal to 4 micrograms/ml are considered interesting. Only one derivative 2 developed better cytotoxicity than the parent compound 1. 相似文献
58.
Bartoli G Bosco M Giuliani A Marcantoni E Palmieri A Petrini M Sambri L 《The Journal of organic chemistry》2004,69(4):1290-1297
The Lewis acid promoted allylation of aldehydes has become an important carbon-carbon bond forming reaction in organic chemistry. In this context, we have developed an alternative over existing catalytic processes, wherein aldehydes are subject in acetonitrile to reaction of allylation with allyltributylstannane in the presence of 1.0 equiv of cerium(III) chloride heptahydrate (CeCl(3).7H(2)O), an inexpensive and mild Lewis acid. The allylation has been accelerated by using an inorganic iodide as a cocatalyst, and various iodide salts were examined. The procedure must use allylstannane reagent instead of allylsilane reagent, desirable for environmental reasons, but high chemoselectivity was observed, and this is opposite the results obtained with other classical Lewis acids such as TiCl(4) and Et(2)O.BF(3). 相似文献
59.
Fernández-Ibáñez P de las Nieves FJ Malato S 《Journal of colloid and interface science》2000,227(2):510-516
Electron transfer between a titanium dioxide/electrolyte solution interface has been studied. As found by other researchers of similar interfaces (TiO(2)- and ZnO-electrolyte solution), a slow consumption of OH(-) ions takes place in this type of interface. A theoretical model has been developed for calculating the change in the Fermi energy of both electrolyte solution and semiconductor, showing that ion consumption from the solution is favoured by the decrease of the difference between their Fermi energies. A kinetic constant (upsilon) is found to characterise the consumption process, its value increasing with electrolyte and semiconductor mass concentrations. Furthermore, this process may be used to estimate the point of zero charge of a titanium dioxide colloidal dispersion. Copyright 2000 Academic Press. 相似文献
60.
Bartoli G Bellucci MC Bosco M Dalpozzo R Marcantoni E Sambri L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(14):2590-2598
Accurate investigations on the role played by an alpha-stereogenic center in controlling the reduction of various classes of beta-hydroxy ketones allowed us to set up a general and highly diastereoselective protocol for the synthesis of 2-alkyl-1,3-diols with 1,2-syn relationship. This methodology is based on the conversion of a beta-hydroxy ketone into the corresponding titanium alcoholate that permits us to organize the substrate in a stable and rigid structure, which stereofacially favors attacking hydride ions. The use of THF as solvent makes available a variety of hydride donors that cover a large spectrum of steric demand: the choice of the more appropriate one depends on the conformational stability of the cyclic intermediate. Excellent results are obtained also in the presence of an additional stereogenic center in the beta-position, even if it exerts a concordant or an opposite steric effect with respect to the alpha-substituent. 相似文献