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161.
Stirring primary-secondary diols in ethyl acetate solvent over Woelm alumina leads to the corresponding primary monoacetates simply, conveniently, and in good yields. In this way, primary hydroxyalkylphenols are converted into acetoxyalkylphenols, and primary arylamines are transformed into the corresponding acetamides. 相似文献
162.
163.
F−-induced decomposition of 3-[3-(tert-butyldimethylsiloxy)phenoxy]-3-phenyl-1,2-dioxetane (5c) yielded an intramolecular redox product (7b), whereas 3-phenoxy-3-(3-siloxyphenyl)-1,2-dioxetane (3) gave normal carbonyl fragments with intense light emission. An isomer (5a) gave light with normal decomposition by CIEEL, though the major process was one to yield an acyloin (7a). 相似文献
164.
1,2-Hemoheptafulvene () was synthesized and reacted with 4-phenyl-1,2,4-triazoline-3,5-dione to yield [4π + 2π] and [6π + 2σ + 2π] cycloadducts. 相似文献
165.
The influence of foreign salt, the basicity or the acidity of macroions and the equivalency of the number of ionic groups of macrocations and macroanions upon alternate multiple adsorption on surfaces of colloidal silica (CS91, 110 nm in diameter) and polystyrene spheres (D1A19, 220 nm) have been studied by electrophoretic light scattering measurements. The macrocations used were poly(4-vinyl-N-n-butyl pyridinium bromide (C4PVP, strongly basic), poly(4-vinyl-N-ethyl pyridinium bromide (C2PVP, strongly basic) and poly(allylamine) (PAL, weakly basic). Sodium poly(styrene sulfonate) (NaPSS, strongly acidic) and sodium polyacrylate (NaPAA, weakly acidic) were used as macroanions. The alternate adsorption disappears even in the presence of a small amount of sodium chloride. The alternate multiple adsorption takes place on the addition of C4PVP first and NaPSS next, PAL first and NaPAA next, NaPAA first and C4PVP next, and NaPAA first and PAL next on the CS91 spheres. The influence of the equivalency of the number of ionic groups of C2PVP and NaPAA has been studied for the adsorption on the D1A19 spheres. The synchronous delicate balancing of the electrostatic interactions among the macrocations, the macroanions and the surfaces of the colloidal spheres is important for the alternate multiple adsorption. 相似文献
166.
Ikeguchi M 《Journal of computational chemistry》2004,25(4):529-541
A partial rigid-body method of molecular dynamics simulations for proteins and membranes is presented. In this method, the symplectic integrator for rigid bodies is combined with the equations of motion for the NPT ensemble. The standard NPT ensemble is extended to the membrane-specific ensembles, the NPAT (constant normal pressure and lateral surface area of membranes and constant temperature) and NPgammaT (constant normal pressure and lateral surface tension of membranes and constant temperature) ensembles. By more than 30-ns simulations of aqueous proteins and hydrated lipid bilayers, the results of the partial rigid-body method demonstrated excellent conservation of total energy and consistent behavior with the traditional constraint method in terms of structural distribution and fluctuation of proteins and lipids. The efficient implementation of the partial rigid-body method in parallel computation is presented, which is shown to work well in large-scale molecular dynamics simulations. 相似文献
167.
Susumu Tajima Tadashige Azami Toshikazu Tsuchiya 《Journal of mass spectrometry : JMS》1977,12(1):24-27
The decomposition of the [C6H5CO]+ ions produced from eight alkyl benzoates by electron impact has been studied. By calculating the heat of formation of [C6H5CO]+ ions from the appearance potential value, it is shown that the ions from C6H5COOR when R?H, CH3, C2H5 have some excess energy, and those where R = n-C3H7, iso-C3H7, n-C4H9, iso-C4H9, iso-C5H11 are produced with more excess energy. It is also shown that by taking this excess energy into account, there is a linear relationship between the heat of formation of the activated complex produced in the reaction [C6H5CO]+→[C6H5]+ + CO and the vibrational degree of freedom of the neutral fragment ? OR. 相似文献
168.
Susumu Tajima Tadashige Azami Haruo Shizuka Toshikazu Tsuchiya 《Journal of mass spectrometry : JMS》1979,14(9):499-502
Single and double hydrogen atom transfers in reactions (1) and (2) in the mass spectra of ethyl benzoate, isopropyl benzoate, and isobutyl benzoate have been investigated with reference to the ortho effect: (1) [C6H5CO2R]+? → [C6H5CO2H]+? (m/z 122) + (R-H); (2) [C6H5CO2R]+? → [C6H5CO2H2]+ (m/z 123) + · (R-2H). It is demonstrated that the intermediate ion [C6H5CO2H2]+ has the protonated benzoic acid structure with the hydrogen atom on the carbonyl group. 相似文献
169.
Susumu Tajima Tamae Yanagisawa Tadashige Azami Toshikazu Tsuchiya 《Journal of mass spectrometry : JMS》1980,15(12):609-612
The temperature effect on the single and double hydrogen atom transfer reactions in o-, m- and p-toluic acid n-butyl esters and isobutyl esters has been investigated. For the meta and para isomers, the abundance of the m/z 137 ion [C8H9O2]+ generated by a double hydrogen atom transfer reaction increases relative to the m/z 136 ion [C8H8O2]+˙ generated by a single hydrogen atom transfer reaction upon lowering the temperature of the ionization chamber. On the other hand, the ratio of the peak abundances [137]+/[136]+ for the ortho isomers is nearly constant when the temperature is changed. It is shown that this is due to the difference between the appearance energies of the m/z 136 and m/z 137 ions. 相似文献
170.
Yoshinori Fujimoto Mitsunori Ohhana Takeshi Terasawa Nobuo Ikekawa 《Tetrahedron letters》1985,26(27):3239-3242
Petrosterol (1), a cyclopropane-containing C29 marine sterol, has been synthesized in a stereocontrolled manner which involves [2,3]-Wittig rearrangement of the propargyl ether (3) yielding the acetylene alcohol (4) with the required C-24, 25 stereochemistry. 相似文献