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51.
Bayesian latent variable regression (BLVR) aims to utilize all available information for empirical modeling via a Bayesian framework. Such information includes prior knowledge about the underlying variables, model parameters and measurement error distributions. This paper improves upon the existing optimization‐based BLVR (BLVR‐OPT) method [1] by developing a sampling‐based Bayesian latent variable regression (BLVR‐S) method that relies on Gibbs sampling. Use of the sampling‐based framework not only provides point estimates, but its ability to generate samples that represent the posterior distribution of the unknown variables, also readily provides error bounds. Features and advantages of this method are demonstrated via examples based on simulated data and real Near‐Infrared (NIR) spectroscopy data. Practical aspects of Bayesian modeling such as determining when the extra computation may be worth the effort are addressed by an empirical study of the effects of the amount of training data and signal to noise ratio (SNR). The benefits of BLVR seem to be most significant when the number of measurements is limited and when noise in output variables is relatively large. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
52.
Pritam Dolui Vikas Tiwari Parul Saini Dr. Tarak Karmakar Koushik Makhal Harshita Goel Dr. Anil J. Elias 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(43):e202200829
An efficient, metal-free, catalyst-free and solvent-free methodology for the reductive amination of levulinic acid with different anilines has been developed using HBpin as the reducing reagent. This protocol offers an excellent method to avoid solvents and added catalysts on the synthesis of different kinds of N-substituted pyrrolidones under metal free conditions. It is also the first report for the synthesis of different pyrrolidones by solvent-free as well as catalyst-free methods. The proposed mechanism for the formation of pyrrolidone has been supported by DFT calculations and control experiments. 相似文献
53.
54.
SbOSb bonds in (Ph3ClSb)2O and PH3SbO are cleaved readily by methanol and acetylacetone. The reactions provide convenient synthetic routes for Ph3Sb(OMe)Cl, Ph3Sb(OMe)2, Ph3Sb(acac)Cl, and Ph3Sb(acac)OH. Characterization of these compounds by infrared, Raman, and 1H NMR spectral measurements is reported. 相似文献
55.
Triphenylbismuth diazide and the dicyanide have been prepared and characterized. Previously reported triphenylbismuth hydroxide cyanide has been shown to be triphenylbismuth dicyanide. A trigonal bipyramidal structure is indicated for both the compounds on the basis of their infrared and laser Raman spectra. The molecular weight and conductance data for the diazide in acetone are also in accord with a molecular structure. The dicyanide is, however, decomposed in solution into diphenylbismuth cyanide and benzonitrile. Thermal decomposition of the solid dicyanide and the diazide has also been studied. The possibility of the conversion of the diazide and the dicyanide into the corresponding dicyanate has been explored. Unlike transition metal azides, the triphenylbismuth diazide does not react with CO. Triphenylbismuth dicyanide could also not be converted into the corresponding dicyanate by reaction with either HgO or MnO2. Reaction with HgO afforded triphenylbismuth oxide and the reaction with MnO2 gave uncharacterized products. 相似文献
56.
I. K. Varma R. N. Goel D. S. Varma 《Journal of polymer science. Part A, Polymer chemistry》1979,17(3):703-713
Polyimides with different proportions of m-phenylene and p-phenylene (or p,p′-biphenylene) were prepared by polymerizing different molar ratios of m-phenylene diamine and p-phenylene diamine (or p,p′-diaminobiphenyl) with pyromellitic dianhydride in dimethylformamide at 0°C. Chemical cyclodehydration of polyamic acids resulted in the corresponding polyimides. Polymers were characterized by infrared (IR), viscosity, and density measurements. Viscosity and density of polymers decreased with an increase on m-phenylene groups in the backbone. The thermal and thermooxidative stabilities were investigated by dynamic thermogravimetry. Stability decreased when m-phenylene groups were introduced in the backbone. 相似文献
57.
Using the well known properties of thes-stage implicit Runge-Kutta methods for first order differential equations, single step methods of arbitrary order can be obtained for the direct integration of the general second order initial value problemsy=f(x, y, y),y(x
o)=y
o,y(x
o)=y
o. These methods when applied to the test equationy+2y+
2
y=0, ,0, +>0, are superstable with the exception of a finite number of isolated values ofh. These methods can be successfully used for solving singular perturbation problems for which f/y and/or f/y are negative and large. Numerical results demonstrate the efficiency of these methods. 相似文献
58.
S. P. Goel G. R. Verma Sanjive Kumar M. P. Sharma 《Journal of Thermal Analysis and Calorimetry》1991,37(2):427-432
A new molybdenum(VI) complex Cs2(NH4)2[Mo3O8(C2O4)3] (CAMO) has been prepared and characterized by chemical analysis and IR spectral studies. Thermal decomposition studies have been made using TG, DTA and DTG techniques. The compound is anhydrous and stable up to 160°C. Thereafter it decomposes in three stages. The first and the second stages occur in the temperature ranges 160–220°C and 220–280°C to give the intermediate compounds having the tentative compositions Cs4(NH4)2[Mo6O16(C2O4)3(CO3)2] and Cs4[Mo6O16(C2O4)2(CO3)2] respectively, the later then decomposing to give the end product Cs2Mo3O10 at 370°C. The end product was characterized by chemical analysis, IR spectral and X-ray studies. 相似文献
59.
The determination of lithium and nitrogen in a variety of materials by thermal neutron activation is described. The nuclear reactions used are 14N(n,p)14C and 6 Li(n,α)3H. Radionuclides. 14C and 3H for counting are isolated by fusion of the irradiated sample in a vacuum system. Data are presented on lithium and nitrogen concentrations in several terrestrial standards. The new method allows reliable measurements on 10–50-mg samples. 相似文献
60.
Atul Goel Dr. Fateh Veer Singh Manish Dixit Deepti Verma Resmi Raghunandan Prakas R. Maulik Dr. 《化学:亚洲杂志》2007,2(2):239-247
A general, two‐step, highly efficient synthesis of 1,2‐diaryl‐, 1,2,3‐triaryl‐, and 1,2,3,4‐tetraarylbenzenes from simple stitching of α‐oxo‐ketene‐S,S‐acetals and active methylene compounds via a lactone intermediate is described. This procedure offers easy access to highly functionalized arylated benzenes that contain sterically demanding groups in good to excellent yields. The novelty of the procedure lies in the construction of aromatic compounds with the desired conformational flexibility along the molecular axis in a transition‐metal‐free environment through easily accessible precursors. Crystal analysis of these arylated benzene scaffolds showed that the peripheral aryl rings are arranged in a propeller‐like fashion with respect to the central benzene ring. Examination of the crystal packing in the structure of a 1,2,3,4‐tetraarylbenzene revealed an N???π interaction between molecules related by a two‐fold screw axis running in the direction of the a axis. Interestingly, the repeating array of N???π interactions around the axis of this 1,2,3,4‐tetraarylbenzene forces the molecules into a helical pattern. 相似文献