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931.
Polymerization of methyl methacrylate with cupric laurate-N,N-dimethyl formamide as initiator system
Prabir Kumar Pal Ajit Kumar Chaudhuri 《Journal of polymer science. Part A, Polymer chemistry》1990,28(11):3123-3135
The polymerization of methyl methacrylate with cupric laurate in combination with N,N-dimethyl formamide as initiator was studied in carbon tetrachloride medium at 60°C. The rate of polymerization was found to be proportional to the 3/2th power of the monomer concentrations and to the square root of both cupric laurate and DMF concentrations. Spectroscopic investigations indicated a ternary complex formation involving cupric ion, methyl methacrylate, and DMF. A reaction scheme is suggested on the basis of these results and various kinetic constants have been evaluated. 相似文献
932.
An ultra-sensitive and highly selective nonextractive fluorimetric method is presented for the rapid determination of aluminium at nano-trace levels using chromotropic acid as a fluorimetric reagent [lambda(ex) = 360 nm and lambda(em) = 390 nm] in the pH range of 4.1-4.7. The fluorescence intensity of the metal chelate (2:3 complex) reaches a constant value within 1/2 hr and remains unchanged for over 48 hr. The fluorescence intensity aluminium concentration calibration curve is collinear between 1 and 300 ng/ml of Al. A constant fluorescence intensity is obtained over a wide range (1:50-1:1500) of Al:reagent molar concentrations. Large excesses of over 60 cations, anions and complexing agents (like tartrate, oxalate, phosphate, thio-urea, SCN(-), etc.) do not interfere in the Al determination. The developed method was successfully used in assaying aluminium in several standard reference materials (Al-bronze, brass, stainless steel) as well as in some environmental and biological samples. The method is very precise and accurate (S.D = +/-0.001 on 10 ng/ml; 11 determinations). 相似文献
933.
N. Sievert A. Fischer U. Klingebiel Prof. Dr. A. Pal M. Noltemeyer 《无机化学与普通化学杂志》2007,633(8):1223-1232
2,2‐Difluor‐1,3‐diaza‐2‐sila‐cyclopentene – Synthesis and Reactions N,N′‐Di‐tert‐butyl‐1,4‐diaza‐1,3‐butadiene reacts with elemental lithium under reduction to give a dilithium salt, which forms with fluorosilanes the diazasilacyclopentenes 1 – 4 ; (HCNCMe3)2SiFR, R = F ( 1 ), Me ( 2 ), Me3C ( 3 ), N(CMe3)SiMe3 ( 4 ). As by‐product in the synthesis of 1 , the tert‐butyl‐amino‐methylene‐tert‐butyliminomethine substituted compound 5 was isolated, R = N(CMe3)‐CH2‐CH = NCMe3. 5 is formed in the reaction of 1 with the monolithium salt of the 1,4‐diaza‐1,3‐butadiene in an enamine‐imine‐tautomerism. 1 reacts with lithium amides to give (HCNCMe3)2SiFNHR, 6 – 12 , R = H ( 6 ), Me ( 7 ), Me2CH ( 8 ), Me3C ( 9 ), H5C6 ( 10 ), 2,6‐Me2C6H3 ( 11 ), 2,6‐(Me2CH)2C6H3 ( 12 ). The reaction of 12 with LiNH‐2.6‐(Me2CH)2C6H3 leads to the formation of (HCNCMe3)2Si(NHR)2, ( 13 ). In the presence of n‐BuLi, 12 forms a lithium salt which looses LiF in boiling toluene. Lithiated 12 adds this LiF and generates a spirocyclic tetramer with a central eight‐membered LiF‐ring ( 14 ), [(HCNCMe3)2Si(FLiFLiNR)]4, R = 2,6‐(Me2CH)2C6H3. ClSiMe3 reacts with lithiated 12 to yield the substitution product (HCNCMe3)2SiFN(SiMe3) R, ( 15 ). The crystal structures of 1 , 5 , 6 , 9 , 11 , 13 , 14 are reported. 相似文献
934.
W. U. Malik S. K. Srivastava Raj Pal Singh Satish Kumar 《Journal of Radioanalytical and Nuclear Chemistry》1977,36(2):469-477
The sorption of univalent, bivalent and trivalent ions has been studied on chromium ferrocyanide gel. The studies reveal a
high sorption capacity for Cs+, Tl+, Ag+, Cu2+, Zn2+, Cd2+, Fe3+ and Th4+. The sorption of monovalent cations show purely ion-exchange mechanism while the uptake of bivalent and trivalent cations
is non-equivalent in nature. Single elution of Rb+, Cs+ and Tl+ has been performed from the columns of this exchanger and the recovery is almost complete in all the cases. Cu2+ and Ag+ get completely adsorbed on the gel column and their elution is not possible probably due to the formation of some new solid
phases. Depending on the Kd values of the metal ions, a large number of separations of radiochemical as well as analytical importance can be performed
on the columns of this exchanger material. 相似文献
935.
Summary Copper(II) salts were reacted with two diamino-dithioether ligands, i.e. 1,3-di(o-aminophenylthio)propane (abbreviated H2L1) and 1,2-di(o-aminophenylthio)xylene (abbreviated H2L2). Mixtures of copper(I) and copper(II) complexes were obtained with Cl– and ClO
4
–
counterions. The major products were the copper(I) complexes, which were obtained pure after recrystallisation from MeCN-MeOH. The ligands lose two protons from the amine functions to form copper(I) complexes of general formula [CuL]X, where X = ClO
4
–
or Cl–. The complexes were oxidised to [CuL]X2 with H2O2 in DMF. Cu(NO3)2 on the other hand gave [CuH2LNO3]NO3. 相似文献
936.
Summary Ru(III)-thiocyanate has been extracted with hexamethylphosphoramide (HMPA) in methyl isobutyl ketone (MIBK). Thus the extractability, sensitivity and selectivity are improved over the simple binary Ru(III) thiocyanate system in spectrophotometric determination of ruthenium in the organic phase. The maximum colour develops on the steam bath, at the acidity range of 1.5–2.5M with HCl and ammonium thiocyanate concentration range of 0.25–0.5M. The colour is completely extractable in MIBK when 1.5–3.0 ml HMPA is used and show maximum absorbance at 570 nm. The colour system obeys Beer's law for 0.7–13 g Ru/ml and the optimum concentration range is 2–13 g/ml. The molar absorptivity and sensitivity are 69401-mole–1 cm–1 and 0.0145 g/cm2 respectively. The percent relative error is 2.72%. The method is very simple and does not require oxidation and subsequent distillation. The method can be applied in the presence of osmium.
Flüssig-flüssig-Extraktion von Ruthenium(III)thiocyanat mit Hexamethylpbosphoratnid: spektrophotometrische Bestimmung in der organischen Phase
Zusammenfassung Ru(III)thiocyanat wurde mit Hexamethylphosphoramid (HMPA) in Methylisobutylketon (MIBK) extrahiert. Die Extrahierbarkeit, Empfindlichkeit und Selektivität wurden im Vergleich zum binären Ru(III)-thiocyanatsystem durch spektrophotometrische Bestimmung in der organischen Phase verbessert. Das Farbmaximum entwickelt sich auf dem Wasserbad in 1,5 bis 2,5M Salzsäure bei einer Ammoniumthiocyanat-Konzentration von 0,25–0,5 Mol/l. Mit 1,5–3,0 ml HMPA läßt sich die Färbung vollständig in MIBK extrahieren und zeigt ein Absorptionsmaximum bei 570 nm. Die gefärbte Lösung entspricht dem Beerschen Gesetz für 0,7–13 g Ru/ml; das Konzentrationsoptimum liegt zwischen 2 und 13 g/ml Die molare Absorptivität und Empfindlichkeit betragen 69401·mol–1·cm–1 bzw. 0,0145g/cm2. Die Methode ist sehr empfindlich; Oxydation und nachfolgende Destillation sind überflüssig. Bei Anwesenheit von Osmium ist dieses vorher zu entfernen.相似文献
937.
A new, simple and rapid method based on the principle of liquid-liquid phase equilibria has been developed for the analysis of binary mixtures of chemically similar organic compounds. The method does not require elaborate instrumentation and can be used to analyse mixtures of members of homologous series. The application of the method has been illustrated by analysing binary mixtures of n-hexane and n-octane; the maximum uncertainty in this analysis is ~2%. 相似文献
938.
N,N'-Diphenyldithiomalonamide, (C6H6. NH. CS)2CH2, is found to be a very suitable gravimetric reagent for nickel(II) and cobalt(II). The complexes, of composition Ni(C15H13N2S2)2 and Co(C15H13N2S2)3, are stable and can be weighed after drying at 110°. Separation from base metals has been studied, and the structural interpretation is supported by DTA, TG, infrared and NMR data. 相似文献
939.
Dr. Gajai Singh Malik Satya Pal Singh Jagdish P. Tandon 《Monatshefte für Chemie / Chemical Monthly》1977,108(1):163-168
The formation of mixed ligand complexes of the title metal ions with 1,10-phenanthroline (Phen) or 2,2-bipyridyl (Bipy) in presence of histidine (His) has been studied pH-metrically. The stepwise formation of 111 mixed ligand complexes has been inferred from the potentiometric titration curves. Initially, a 11 metal—Phen or—Bipy complex is formed in the lower buffer region and then the addition ofHis takes place resulting in 111 ternary complex formation. The formation constants (K
MAL
) of the resulting mixed ligand complexes have been calculated at 30±1°C (=0.1 KNO3) and the values have been found to be higher than the formation constants of 12 and lower than those of 11 metal—His complexes. The order of stability in terms of metal ions follows the order, Ni(II)>Zn(II)>Cd(II).With 2 Figures 相似文献
940.