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141.
A dead-time correction system, based on CAMAC-modules is developed for the -ray spectrometry of short-lived radionuclides. The linearity of the method is realized up to about 104 cps. 相似文献
142.
I. Salma L. Almási É. Zemplén-Papp 《Journal of Radioanalytical and Nuclear Chemistry》1990,140(2):263-270
A CAMAC system was installed for pulse height analysis and correction of counting losses due to the dead-time of a multichannel analyzer and the pulse pile-up. A computer program was developed to control the whole system, and to collect and store data in both conventional and cyclic measurement modes. 相似文献
143.
A number of new and interesting 2-amino-4-(N-substituted)imino-4,5-dihydrothiazoles were synthesized by reacting thiourea (or thiourea hydrochloride) with N-alkyl- or N,N-dialkyl-N′-p-toluenesulfonyl-α-chloroacetamidines, where the N,N-alkyl groups were ethyl, cyclohexyl, benzyl, β-phenethyl, (3,5-dimethyl-1-adamantyl)-methyl, as well as N,N-dimethyl- and N,N-pentamethylene. Reactions of N-alkyl-N-p-toluenesulfonyl-2-chloroacetamidines (substituents being N-ethyl, N-benzyl and N,N-dimethyl) with thiourea hydrochloride in hot 2-propanol furnished 2-amino-4-(p-toluenesulfonyl)imino-4,5-dihydrothiazole (in 51, 60 and 65% yields, respectively) and the corresponding amine hydrochloride. In hot acetone or butanone, the reactions of these N-sulfonyl-2-chloroacetamidines with excess thiourea provided 2-amino-4-N-(alkyl or N,N-dialkyl)imminium-4,5-dihydrothiazole chlorides in 25–80% yield. The by-product from these reactions was p-toluenesulfonamide. The structures of the products were established by chemical transformations and spectral methods (nmr and mass spectra). 相似文献
144.
By using the electronic wave functions obtained from an ab initio calculation, including the spin‐orbit coupling, the electronic transition moments have been investigated for two bound states of symmetry Ω = 1/2 and Ω = 3/2 of the molecular ion KRb+. Based on a canonical functions approach for the determination of the vibrational wave functions, the matrix elements have been calculated for the bound states considered for v = 0, 10, 20 with v′‐ v = 0, 1, 2, …, 6; by using the same canonical approach, the eigenvalues and abscissas of the corresponding turning points (rmin and rmax) have been investigated for these states that obtained from a theoretical ab initio calculation up to v = 105. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
145.
Imene Mejri Mohamed Kadri Younes Abdelhamid Ghorbel 《Journal of Sol-Gel Science and Technology》2006,40(1):3-8
Aerogel and xerogel sulphated zirconia with defined atomic ratio S/Zr = 0.5 and molar hydrolysis ratio h = nH2O/nZrO2 = 3 show different textural and structural properties after calcination at high temperatures. The aerogel obtained just after
solvent evacuation develops only the tetragonal phase, whereas the xerogel dried in an oven is amorphous. Heating to a temperature
above 833 K, leads to transition of the tetragonal phase to the monoclinic one for the two solids, due to sulphur loss but
the tetragonal phase remains stable for the aerogel . Raman, Infrared and XPS spectroscopies show that the loss of the sulphur
at high temperatures seems to be easier for the xerogel than for the aerogel. 相似文献
146.
An air pollution study was conducted at two urban residential sites in Budapest from 9 April to 17 May 1996. Size-fractionated aerosol samples were simultaneously collected on a daily basis, and meteorological conditions were recorded at both sampling sites. Stacked filter units (SFUs) with an upper size inlet cutoff were used as sampling devices separating the urban aerosol into coarse [about 2- to 10-μm equivalent aerodynamic diameter (EAD)] and fine (<2 μm EAD) size fractions. In addition, atmospheric concentrations of some criteria pollutants, i.e., NO, NO2, SO2, CO, and total mass of the suspended particulate matter (TSP) were measured every half-hour at one of the sampling sites with commercial equipment. The SFU filters were weighed and analyzed by a light reflectance technique, particle-induced X-ray emission analysis, and instrumental neutron activation analysis. Atmospheric concentrations for 31 aerosol species have been obtained so far. The analytical results were used to characterize the levels and the multielemental composition of the urban aerosol at both sampling sites and for both size fractions, to investigate the atmospheric concentrations and diurnal variation of the criteria pollutants, and to compare the time trends of aerosols and trace gases. The present paper reports on the status of the air pollution study and gives a discussion of the results. 相似文献
147.
4‐Bromo‐1‐phenyl‐3,5‐pyrazolidinedione 2 reacted with different nucleophilic reagents to give the corresponding 4‐substituted derivatives 3–8 . The cyclized compounds 9–11 were achieved on refluxing compounds 3 , 4 or 6a in glacial acetic acid or diphenyl ether. 4,4‐Dibromo‐1‐phenyl‐3,5‐pyrazolidinedione 12 reacted with the proper bidentates to give the corresponding spiro 3,5‐pyrazolidinediones 13–15 , respectively. The 4‐aralkylidine derivatives 16a‐c , were subjected to Mannich reaction to give Mannich bases 17a‐c‐22a‐c , respectively. 4‐(p‐Methylphenylaminomethylidine)‐1‐phenyl‐3,5‐pyrazolidinedione 23 or 4‐(p‐methylphenylazo)‐1‐phenyl‐3,5‐pyrazolidinedione 29 were prepared and reacted with active nitriles, cyclic ketones and N,S‐acetals to give pyrano[2,3‐c]pyrazole, pyrazolo[4′,3′:5,6]pyrano[2,3‐c]pyrazole, spiropyrazole‐4,3′‐pyrazole and spiropyrazole‐4,3′‐[1,2,4]triazolane derivatives 24–34 , respectively. 相似文献
148.
Gaël Poirier Younes Messaddeq Marcel Poulain 《Journal of solid state chemistry》2005,178(5):1533-1538
Transparent glasses were synthesized in the NaPO3-BaF2-WO3 ternary system and several structural characterizations were performed by X-ray absorption spectroscopy (XANES) at the tungsten LI and LIII absorption edges and by Raman spectroscopy. Special attention was paid to the coordination state of tungsten atoms in the vitreous network.XANES investigations showed that tungsten atoms are only six-fold coordinated (octahedra WO6) and that these glasses are free of tungstate tetrahedra (WO4).In addition, Raman spectroscopy allowed to identify a break in the linear phosphate chains as the amount of WO3 increases and the formation of P-O-W bonds in the vitreous network indicating the modifier behavior of WO6 octahedra in the glass network. Based on XANES data, we suggested a new attribution of several Raman absorption bands which allowed to identify the presence of W-O− and WO terminal bonds and a progressive apparition of W-O-W bridging bonds for the most WO3 concentrated samples (?30% molar) due to the formation of WO6 clusters. 相似文献
149.
Knoevenagel reactions involving carbonyl compounds and active methylene derivatives have been studied in the presence of alumina, KSF and K10 montmorillonites. With addition of water the ester group undergoes hydrolysis. A route is disclosed for the synthesis of coumarine compounds catalyzed by solid supports. 相似文献
150.
A novel sequential injection (SI) method was developed for the determination of penicillamine (PA) and ephedrine (EP) based on the reaction of these drugs with tris(bipyridyl)ruthenium(II) (Ru(bpy)32+) and peroxydisulfate (S2O82−) in the presence of light. Derivatization of PA and EP with aldehydes has resulted in a significant enhancement of the chemiluminescence emission signal by at least 25 times for PA and 12 times for EP, leading to better sensitivities and lower detection limits for both drugs. The instrumental setup utilized a syringe pump and a multiposition valve to aspirate the reagents, (Ru(bpy)32+ and S2O82−), and a peristaltic pump to propel the sample. The experimental conditions affecting the derivatization reaction and the chemiluminescence reaction were systematically optimized using the univariate approach. Under the optimum conditions linear calibration curves between 0.2–24 μg mL−1 for PA and 0.2–20 μg mL−1 for EP were obtained. The detection limits were 0.1 μg mL−1 for PA and 0.03 μg mL−1 for EP. The procedure was applied to the analysis of PA and EP in pharmaceutical products and was found to be free from interferences from concomitants usually present in these preparations. 相似文献