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11.
Optimized conditions for hydrocarbon group type analysis of base oils by thin-layer chromatography-flame ionisation detection 总被引:1,自引:0,他引:1
The results of research on the optimization of the thin-layer chromatography-flame ionisation detection for the determination of group composition of natural base oils, including separation of the aromatics into subgroups, are presented. Neutral base oils obtained in several steps of refining from vacuum distillation petroleum fractions are the most difficult to analyze by hydrocarbon group type analysis (HGTA) because of the high content of aliphatic fragments in their molecules. Factors affecting the accuracy and precision of the results were identified. The paper presents the analytical procedure, including two different calibration methods, as well as the results of studies on the reproducibility of HGTA of typical base oils of different viscosity classes under the optimized conditions. The same conditions were found suitable for HGTA of other high-boiling petroleum fractions by TLC with flame ionisation detection. The paper also introduces a new procedure for reproducible determination of polar fractions in base oils utilizing solid-phase extraction columns, and presents a corrected procedure for the determination of saturated compounds and aromatics (mono-, bi- and polycyclic) in base oils by column liquid chromatography. 相似文献
12.
M. Mikoŀajczyk J. Michalski A. Halpern R. Sochaxcka 《Monatshefte für Chemie / Chemical Monthly》1969,100(4):1266-1273
Zusammenfassung An den Modellverbindungen Dialkylchlorthiophosphat (RO)2P(S)Cl (R=Me, Et, n-Pr) und Diphenylchlorthiophosphat (PhO)2P(S)Cl wurde der Austausch Chlorid—Radiochlorid am Thiophosphorylzentrum untersucht. Die bimolekularen Geschwindigkeitskonstanten, die Aktivierungsenergien und Aktivierungsentropien wurden berechnet. Der Einfluß von Substituenten auf bimolekulare Substitutionsreaktionen am vierfach koordinierten Phosphoratom wurde diskutiert.
Mit 3 Abbildungen 相似文献
Chlorine isotopic exchange at phosphorus atoms, I.: Chloridothiophosphates
The chloride—radiochloride ion exchange at the thiophosphoryl centre has been studied using dialkylchloridothiophosphates (RO)2P(S)Cl (R=Me, Et, n-Pr) and diphenylphosphorochloridothionate, (PhO)2P(S)Cl, as model compounds. The bimolecular rate constants, energies and entropies of activation have been calculated. Effects of the substituents in the bimolecular displacement reaction on four-coordinated phosphorus atom have been discussed.
Mit 3 Abbildungen 相似文献
13.
The Balancing Domain Decomposition algorithm uses in each iteration solution of local problems on the subdomains coupled with a coarse problem that is used to propagate the error globally and to guarantee that the possibly singular local problems are consistent. The abstract theory introduced recently by the first-named author is used to develop condition number bounds for conforming linear elements in two and three dimensions. The bounds are independent of arbitrary coefficient jumps between subdomains and of the number of subdomains, and grow only as the squared logarithm of the mesh size . Computational experiments for two- and three-dimensional problems confirm the theory.
14.
15.
A new computer controlled equipment for carrier concentration profile determination of silicon structures by a spreading resistance technique is presented. The required data and plots can easily be obtained by means of a new software package, which has been specially developed for this purpose. Measurements have been performed on different structures in order to verify the suitability of both the measuring system and the software package. The reproducibility has been found to be within 5% for the investigated structures. 相似文献
16.
Maj-Urawska M Ziemianek D Mikołajczuk A Mieczkowski J Lewenstam A Hulanicki A Sokalski T 《Analytical and bioanalytical chemistry》2003,376(4):524-526
The properties of the carbonate neutral carrier 4-( n-hexadecyl)-3-nitro-1-trifluoroacetylbenzene were compared with those of a similar carrier, without a nitro group, studied previously. In spite of differences in the Hammett constant of the carbonyl group responsible for interaction with the analyte, the analytical characteristics of both carriers, measured under the same conditions, were comparable. Special care was taken to avoid the presence of an excessive carbon dioxide level in the diffusion layer at the membrane-solution interface. The internal reference solution was prepared without carbonate components; the external solution was protected from contact with atmospheric carbon dioxide. Under such conditions the detection limit of both electrodes was extended to 10(-11 )mol L(-1), and the selectivity towards salicylate, chloride, and acetate was significantly improved. 相似文献
17.
Marian Grobelny 《Journal of fluorine chemistry》1977,9(3):187-207
A study for AlF3 crystallization from water solution was performed in the temperature range 100 to 200°C.Four solid phases were found to be precipitated, AlF3.3H2O (up to ca.120°C, cubic α-AlF3.H2O (decomposition of AlF3.3H2O in suspension), hexagonal β -AlF3.H2O (direct from solution) and the hydroxyfluoride Al(OH,F)3.H2O with an F/Al ratio of ca. 2.5 (hydrolysis of AlF3). The extent of hydrolysis was established as a function of the initial AlF3 concentration.X-ray diffraction and thermogravimetric data for the monohydrates were given and differences between the two indicated. 相似文献
18.
Peter Segl'a Martina Palicov Dusan Miklos Marian Koman Milan Melník Maria Korabik Jerzy Mrozinski Tadeusz Glowiak Markku R. Sundberg Peter Lnnecke 《无机化学与普通化学杂志》2004,630(3):470-478
Synthesis and characterization of seven new complexes [Cu(2‐MeSnic)2(CH3OH)]2 (where 2‐MeSnic is 2‐methylthionicotinate), [Cu(2‐MeSnic)2L2]2 (where L is pyridine — py, ethylnicotinate — Etnic and butylnicotinate — Bunic), [Cu(2‐MeSnic)2L2(H2O)2] (where L is py and nicotinamide — nia) and [Cu(2‐MeSnic)2(N‐Menia)2(H2O)2]·2H2O (where N‐Menia is N‐methylnicotinamide) are reported. The characterization were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic susceptibility measurements over a temperature range of 1.8 — 300 K or 70 — 300 K. Three complexes of different type were studied by X‐ray analysis. The molecule of [Cu(2‐MeSnic)2(CH3OH)]2 has dimeric paddle‐wheel cage structure with a tetragonal pyramidal arrangement around CuII. The dimer results from the fact that carboxyl groups of four 2‐MeSnic anions function as bridging in a syn‐syn arrangement. On the other hand [Cu(2‐MeSnic)2(py)2]2 forms dimers with hexacoordinated CuII atoms in highly distorted coordination octahedra, each with two oxygen atoms of bridging carboxyl groups in an anti‐anti arrangement of two 2‐MeSnic anions, with two oxygen atoms of one asymmetrically chelating 2‐MeSnic anion and with two nitrogen atoms of two pyridine ligands. The temperature independent EPR spectrum for this complex exhibits an axial signal which corresponds to almost isolated S = 1/2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = —0.65 cm—1. The CuII atom in complex [Cu(2‐MeSnic)2(py)2(H2O)2] is hexacoordinated in an elongated centrosymmetrical tetragonal‐bipyramidal arrangement (4 + 2). Based on the molecular structure the electronic, infrared, electron paramagnetic resonance spectra and magnetic properties are discussed and stereochemistry as well as the mode of ligand coordination in new solid complexes under study have been determined. 相似文献
19.
Both C(2)-P bond breaking and formation in the S-C-P(+) system do not occur according to the antiperiplanar lone pair hypothesis. Experiments using 2-phosphonio derivatives of 5-tert-butyl-1,3-dithiane and cis-4,6-dimethyl-1,3-dithiane are against the participation of higher-energy boat conformers as reactive intermediates. The results obtained support a possibility of conformational adjustment in the course of the reaction. Stereoelectronic control of the C(2)-P bond breaking and formation results from interplay of several factors. The role of the n(S)-sigma(C(2))(-)(P) and sigma(C(4,6))(-)(S)-sigma(C(2))(-)(P) hyperconjugation, as well as of the repulsive interactions between lone electron pairs pi(S) of endocyclic sulfur atoms and pi-electrons of the phenyl ring(s) connected with phosphorus, is discussed. 相似文献
20.
NEW PHTHALOCYANINE PHOTOSENSITIZERS FOR PHOTODYNAMIC THERAPY 总被引:2,自引:1,他引:2
Nancy L. Oleinick Antonio R. Antunez Marian E. Clay Boris D. Rihter Malcolm E. Kenney 《Photochemistry and photobiology》1993,57(2):242-247
Six new aluminum and silicon phthalocyanines have been synthesized and their photocytotoxicity toward V79 cells has been studied. The compounds that have been prepared are: AIPcOSi(CH3)2(CH2),N(CH3)2, I; AIPcOSi(CH3)2(CH2)3N(CH3)3+I?, II; CH3SiPcOSi(CH3)2(CH2)3N(CH3)2, III; HOSiPcOSi(CH3)2(CH2)3N(CH3)2, IV; HOSiPcOSi(CH3)2(CH2)3)3(CH3)3+I?, V; and SiPc[OSi(CH3)2(CH2)3N(CH3)3+I?]2, VI. Relative growth delay values for compounds I-VI and relative cytotoxicity values for compounds I, II, IV, V and VI have been determined. Compounds I and II have been shown to be comparable in photocytotoxicity to what is presumed to be AIPcOH.xH2O, and compound IV has been shown to have greater activity. The classes of compounds to which these six compounds belong appear to have potential for photodynamic therapy. 相似文献