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141.
M. V. Encinas A. M. Rufs E. Norambuena C. Giannotti 《Journal of polymer science. Part A, Polymer chemistry》1997,35(15):3095-3100
The polymerization rate of methyl methacrylate photosensitized by p-nitroacetanilide in the presence of triethylamine was measured as a function of the amine and monomer concentrations. The polymerization proceeds readily in high-polarity media (acetonitrile/monomer) but is negligible in nonpolar media. The polymerization rate increases with the amine concentration up to 0.15M. Further increase in amine concentration does not change the polymerization rate. A similar behavior was observed for the photobleaching of the nitro compound. ESR studies show the formation of a nitro and an amine free radical, the latter free radical being the active species that adds to the monomer. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3095–3100, 1997 相似文献
142.
The complex [Cu(HGLYO)2(bipy)] ( I ) and two new copper(II) coordination polymers with the formulas {[Cu(GLYO)1‐x(ox)x(bipy)]·2.5H2O}n [GLYO = glycolato dianion, ox = oxalato dianion, bipy = 2, 2′‐bipyridine, x = 0.56 (in II ) or 0.71 (in III )] were synthesized using copper(II) glycolate as starting material and were characterized by IR, UV‐Vis and EPR spectrometry, by magnetic measurements ( II and III ), and by single‐crystal X‐ray diffractometry. Both II and III crystallized as one‐dimensional polymers composed of Cu2O2‐centred dimers with a Cu‐Cu distance of 3.282(1)Å (mean of II and III ) that are linked by Cu2(OCO)2 rings with a Cu‐Cu distance of 5.237(1)Å (mean of II and III ), both dianions acting as (μ‐1, 1, 2, 3) three‐way bridges connecting the two copper atoms of one dimer with one copper atom of a neighbouring dimer. Each copper atom is coordinated tetragonally in a CuN2O4 chromophore. In the mononuclear complex I the copper atom has a tetragonally distorted octahedral environment. 相似文献
143.
The crystal structure of the title complex, [Cd(tsac)2(py)3], has been determined by single crystal X‐ray diffractometry. It crystallizes in the monoclinic space group C2/c with Z = 8.The Cd 2+ cation is at the center of a square‐ bipyramidal environment, equatorially coordinated to two thiosaccharinate anions through their sulfur atoms and the nitrogen atom of one of them acting as a bidentate ligand. Nitrogen atoms of pyridine molecules occupy the fourth equatorial position and the two axial ones. The infrared and electronic spectra of the complex were briefly discussed. Its thermal stability was investigated by thermogravimetric and differential thermal analysis. 相似文献
144.
Florian Breitsameter Hans-Peter Schrdel Alfred Schmidpeter Heinrich Nth Susana Rojas-Lima 《无机化学与普通化学杂志》1999,625(8):1293-1300
Ylide Adducts of Pentele Trichlorides Ylides Ph3PCR2 form 1 : 1 adducts with PCl3, AsCl3 und SbCl3. The addition of HCl to dichlorophosphanyl- und dichloroarsanyl ylides also leads to such adducts. In solution the PCl3 adducts 2 are dissociated into ions. For the AsCl3 adducts 3 b and 3 e of triphenylphosphonium ethylide and isopropylide X-ray analyses show distinctly different degrees of transition from a zwitterionic ψ-tbp to a cationic ψ-tetrahedral structure. The SbCl3 adduct 4 b of the triphenylphosphonium ethylide on the other hand forms a rather asymmetric dimer and approaches a square-pyramidal geometry at the antimony atom. The 2 : 1 ylide adducts 11 with PCl3 form in solution the dications (Ph3PCR2)2PCl2+. The 2 : 3 adduct 15 of triphenylphosphonium methylide to AsCl3 also has an ionic structure in the crystal. There are cations (Ph3PCH2)2AsCl2+, which pairwise join with two AsCl3 molecules to form doubly charged supracations in the presence of As2Cl82– as counterions. 相似文献
145.
146.
Response surface methodology (RSM) was employed for the first time to optimize high pressure extraction (HPE) conditions of bioactive compounds from pansies, namely: pressure (X1: 0–500?MPa), time (X2: 5–15?min) and ethanol concentration (X3: 0–100%). Consistent fittings using second-order polynomial models were obtained for flavonoids, tannins, anthocyanins, total reducing capacity (TRC) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. The optimum extraction conditions based on combination responses for TRC, tannins and anthocyanins were: X1?=?384?MPa, X2?=?15?min and X3?=?35% (v/v) ethanol, shortening the extraction time when compared to the classic method of stirring (approx. 24?h). When the optimum extraction conditions were applied, 65.1?mg of TRC, 42.8?mg of tannins and 56.15?mg of anthocyanins/g dried flower were obtained. Thus, HPE has shown to be a promising technique to extract bioactive compounds from pansies, by reducing the extraction time and by using green solvents (ethanol and water), for application in diverse industrial fields. 相似文献
147.
Susana H. Tarulli Oscar V. Quinzani Prof. Dr. Sandra D. Mandolesi Jorge A. Guida Gustavo A. Echeverría Oscar E. Piro Eduardo E. Castellano 《无机化学与普通化学杂志》2009,635(11):1604-1612
A series of palladium(II) thiosaccharinates with triphenylphosphane (PPh3), bis(diphenylphosphanyl)methane (dppm), and bis(diphenylphosphanyl)ethane (dppe) have been prepared and characterized. From mixtures of thiosaccharin, Htsac, and palladium(II) acetylacetonate, Pd(acac)2, the palladium(II) thiosaccharinate, Pd(tsac)2 (tsac: thiosaccharinate anion) ( 1 ) was prepared. The reaction of 1 with PPh3, dppm, and dppe leads to the mononuclear species Pd(tsac)2(PPh3)2 · MeCN ( 2 ), [Pd(tsac)2(dppm)] ( 3 ), Pd(tsac)2(dppm)2 ( 4 ), and [Pd(tsac)2(dppe)] · MeCN ( 5 ). Compounds 2 , 4 , and 5 have been prepared also by the reaction of Pd(acac)2 with the corresponding phosphane and Htsac. All the new complexes have been characterized by chemical analysis, UV/Vis, IR, and Raman spectroscopy. Some of them have been also characterized by NMR spectroscopy. The crystalline structures of complexes 3 , and 5 have been studied by X‐ray diffraction techniques. Complex 3 crystallizes in the monoclinic space group P21/n with a = 16.3537(2), b = 13.3981(3), c = 35.2277(7) Å, β = 91.284(1)°, and Z = 8 molecules per unit cell, and complex 5 in P21/n with a = 10.6445(8), b = 26.412(3), c = 15.781(2) Å, β = 107.996(7)°, and Z = 4. In compounds 3 and 5 , the palladium ions are in a distorted square planar environment. They are closely related, having two sulfur atoms of two thiosaccharinate anions, and two phosphorus atoms of one molecule of dppm or dppe, respectively, bonded to the PdII atom. The molecular structure of complex 3 is the first reported for a mononuclear PdII‐dppm‐thionate system. 相似文献
148.
César Menor‐Salván Dr. Dra. Marta Ruiz‐Bermejo Marcelo I. Guzmán Dr. Susana Osuna‐Esteban Sabino Veintemillas‐Verdaguer Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(17):4411-4418
From urea to nucleobases : Freeze–thaw cycles in urea ( 1 ) solutions under methane/nitrogen atmospheres lead, with application of an energy source, to the synthesis of pyrimidines (mainly cytosine ( 2 ) and uracil ( 3 )), triazines (such as cyanuric acid ( 4 )), and adenine. This synthesis appears to be dependent on the atmosphere and the freezing conditions. At room temperature, hydantoin ( 5 ) is obtained. However, a freezing urea/water system subjected to an energy source under an inert atmosphere generates s‐triazines.
149.
A laser-induced fluorescence (LIF) system was optimized using a solution of Micrococcus luteus in ethanol/water 50% (v/v) to obtain spectra in the gas phase of 46 bioaerosols. Experimental designs such as Plackett-Burman and factorial design were applied. The fluorescence spectra were treated chemometrically by principal component analysis, linear discriminant analysis and hierarchical cluster analysis to classify the microorganisms according to family, morphology and gram. The best results were obtained using LDA. The method was applied to air samples and the LIF results allowed to characterize bioaerosols reliability. The robustness of the technique was demonstrated by the identification of many bacteria. 相似文献
150.