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71.
Birendra K. Agrawal Madhup Chandra Badri V. Agarwala Arun K. Dey 《Transition Metal Chemistry》1978,3(1):243-246
Summary Mixed ligand complexes of copper(II), zinc(II), nickel(II) and cobalt(II) ions involving 1,10-phenanthroline (phen) as primary and 3,5-dinitrosalicylic acid (dnsa), 5-nitrosalicylic acid (nsa), 5-chlorosalicylic acid (csa) and 3,5-dibromosalicylic acid (dbsa) as secondary ligands in solution have been investigated potentiometrically [25°, µ = 0.1 M [NaClO4], medium 50% v: v aqueous ethanol]. The stability order of mixed ligand complexes with respect to the metal ions obeys the natural order: cobalt(II) < nickel(II) < copper(II) > zinc(II). The stabilities of the heterometal chelates have been compared with the corresponding homometal chelates of the secondary ligands and have been interpreted in terms of metal-ligand effects and coulombic interactions between various ligand anion species present. 相似文献
72.
Summary The formation of ternary complexes of the MAL3– type [where M = CuII, NiII and ZnII ; A = nitrilotriacetic acid (NTA); L = 1-hydroxy-2-naphthoic acid (1,2 HNA) and 2-hydroxy-1-naphthoic acid (2,1 HNA)] have been studied potentiometrically in 50% v/v aqueous — ethanol (25° and µ = 0.1). Under identical conditions the binary complexes of the 1,2- and 2,1-HNA ligands have also been examined. The values of mixed ligand formation constants KMAL have been found to be lower than KML (first step formation constant of binary complexes) and even less than
(second step formation constant of binary complexes). 相似文献
73.
74.
Summary Xylenol orange reacts very sensitively with gallium(III), indium (III) and thallium(III) to form reddish violet colored chelates having max 560 nm in case of Ga and In and max 590 nm in case of Ti at PH 4.0. The molar ratio for all the chelates is 1 1 (metal reagent). Optimum conditions including the range for adherence to Beer's law, effect of PH on the color intensity, effect of excess reagent, and sensitivity are reported for the photometric determination of these metal ions using Xylenol orange.
Zusammenfassung Xylenolorange reagiert sehr empfindlich mit Gallium(III), Indium(III) und Thallium(III) unter Bildung rötlich-violetter Chelate mit einem Absorptionsmaximum bei 560 nm im Falle von Ga und In bzw. 590 nm für Tl bei pH 4,0. Das Molverhältnis ist in jedem Fall 11. Die besten Arbeitsbedingungen, der Gültigkeitsbereich des Beerschen Gesetzes, der Einfluß des PH auf die Farbintensität und des Reagensüberschusses sowie die Empfindlichkeit werden für die photometrische Bestimmung der genannten Ionen angegeben.相似文献
75.
Effects of hydrogen-bond environment on single particle and pair dynamics in liquid water 总被引:2,自引:0,他引:2
We have performed molecular dynamics simulations of liquid water at 298 and 258 K to investigate the effects of hydrogen-bond
environment on various single-particle and pair dynamical properties of water molecules at ambient and supercooled conditions.
The water molecules are modelled by the extended simple point charge (SPC/E) model. We first calculate the distribution of
hydrogen-bond environment in liquid water at both temperatures and then investigate how the self-diffusion and orientational
relaxation of a single water molecule and also the relative diffusion and relaxation of the hydrogen-bond of a water pair
depend on the nature of the hydrogen-bond environment of the tagged molecules. We find that the various dynamical quantities
depend significantly on the hydrogen-bond environment, especially at the supercooled temperature. The present study provides
a molecular-level insight into the dynamics of liquid water under ambient and supercooled conditions. 相似文献
76.
G. Venkat Reddy A. Chandra Shekhar A. Ravi Kumar G. Sathaiah B. Narsaiah P. Shanthan Rao 《Journal of heterocyclic chemistry》2012,49(3):687-690
Studies on synthetic design of 7,8‐imidazole fused fluoroquinolones from 8‐amino‐6‐fluoro‐4‐hydroxy‐N‐methyl‐7‐(methyl amino)quinoline‐3‐carboxamide and ketones/carboxylic acids and their antibacterial activity. 相似文献
77.
Asit K. Chandra Shingo Urata Tadafumi Uchimaru Masaaki Sugie Akira Sekiya 《国际化学动力学杂志》2002,34(8):500-507
Kinetics and mechanism of the hydrogen abstraction reaction between trifluoromethyl formate, CF3OCHO, and OH radical have been investigated by using ab initio molecular orbital theory up to G2(MP2) level. The hydrogen abstraction rate constant has been calculated for the first time over a temperature range of 250–450 K by using standard transition state theory including the tunneling correction. Arrhenius parameters of the reaction have been estimated from the temperature dependence of the calculated rate constant. The calculated value for the rate constant (2.0 × 10?14 cm3 molecule?1 s?1) at 298 K is found to be in very good agreement with the recent experimental results. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 500–507, 2002 相似文献
78.
79.
Umesh Chandra J. N. Tayal Purna Nand 《Fresenius' Journal of Analytical Chemistry》1968,238(6):457-459
Summary A volumetric method for the estimation of streptomycin sulphate in pharmaceuticals is based on the quantitative discharge of the violet colour of the maltol-iron complex, produced when streptomycin is hydrolysed in alkaline medium and treated with ferric chloride, by potassium permanganate. It is simple, accurate and other antibiotics such as dihydrostreptomycin, sodium salt of benzyl penicillin, chloramphenicol do not interfere. Procain penicillin has to be separated by extractio with chloroform.
Zusammenfassung Die beschriebene volumetrische Streptomycinbestimmung in Arzneimitteln beruht auf dem Abbau des Streptomycins in alkalischer Lösung zu Maltol, Bildung des Maltol-Eisen(III)-Komplexes und Titration mit Permanganat bis zur Entfärbung. Das Verfahren ist einfach auszuführen und gibt Werte von befriedigender Genauigkeit. Dihydrostreptomycin, Chloramphenicol sowie das Natriumsalz des Benzylpenicillins stören nicht. Procain-Penicillin muß vorher durch Extraktion mit Chloroform abgetrennt werden.相似文献
80.