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11.
VOF3 is soluble in acetonitrile but is slowly reduced to give a vanadyl (IV) species as one product. It reacts rapidly with Me3SiNet2 in MeCN below ambient temperature; fluorine is replaced by -NEt2 ligands but the spectroscopic and magnetic properties of the products indicate that, in addition, reduction to VIV occurs not some extent. The products are formulated as VOF3-n(NEt2)n containing small quantities of VOF2-m(NEt2)m(NEt2H) (n = 1-3, m = 0-2). A similar reaction occurs between VOF3 and Me3SiOMe but with Me3SiOSiMe3 only VO2F is formed. 相似文献
12.
Carl M. Bender Fred Cooper Gerald Guralnik Harvey A. Rose David H. Sharp 《Journal of statistical physics》1980,22(6):647-660
We discuss the simple, randomly driven systemdx/dt = –x –x3 +f(t), wheref(t) is a Gaussian random function or stirring force with f(t)f(t) = (t – t). We show how to obtain approximately the coefficients of the expansion of the equal-time Green's functions as power series in (1/R)n, whereR is the internal Reynolds number ()1/2/, by using a new expansion for the path integral representation of the generating functional for the correlation functions. Exploiting the fact that the action for the randomly driven system is related to that of a quantum mechanical anharmonic oscillator with Hamiltonianp
2/2 +m
2
x
2/2 +vx
4 +x
6/2, we evaluate the path integral on a lattice by assuming that thex
6 term dominates the action. This gives an expansion of the lattice theory Green's functions as power series in 1/(a)1/3, wherea is the lattice spacing. Using Padé approximants to extrapolate toa = 0, we obtain the desired large-Reynolds-number expansion of the two-point function.Supported financially by the National Science Foundation and the U.S. Department of Energy. 相似文献
13.
Kim Sharp 《Journal of computational chemistry》1991,12(4):454-468
The finite difference method for solving the Poisson–Boltzmann equation is used to calculate the reaction field acting on a macromolecular solute due to the surrounding water and ions. Comparisons with analytical test cases indicate that the solvation forces can be calculated rapidly and accurately with this method. These forces act to move charged solute atoms towards the solvent where they are better solvated, and to screen interactions between charges. A way of combining such calculations with conventional molecular dynamics force fields is proposed which requires little modification of existing molecular dynamics programs. Simulations on the alanine dipeptide show that solvent forces affect the conformational dynamics by reducing the preference for internal H-bonding forms, increasing the R-alpha helix preference and reducing transition barriers. These solvent effects are similar to previous explicit solvent simulations, but require little more computation than vacuum simulations. The method should scale up with little increase in computational cost to larger molecules such as proteins and nucleic acids. 相似文献
14.
Bis(methyl)disulphide and the organometallic compound {(Cp)Mo(CO)3}2 in low oxidation state under photolysis give especially with the hexa-fluorobut-2 yne a 18-electron olefin complexe {(Cp)Mo(CO)3(CF3C2CF3SCH3)}. The new compounds are reported and the reaction discussed. 相似文献
15.
Rhenium and uranium hexafluorides oxidise iodine in iodine pentafluoride at ambient temperature to give the I2+ cation. With UF6 additional reaction occurs to give β-uranium pentafluoride as one product (J.A. Berry, A. Prescott, D.W.A. Sharp, and J.M. Winfield, ., 1977, , 247). Further work on the latter reaction together with an electronic spectroscopic study of the oxidation of I2 by phosphorus pentafluoride in IF5, suggests that the fate of the I2+ cation depends on the nature and quantity of the oxidising agent. Oxidation of I2 by PF5 can be conveniently followed by monitoring its visible spectrum. The reaction occurs over several hours and eventually an apparent equilibrium between I2 and I2+ results. Formation of I2+UF6?is rapid and, with the mole ratio UF6:I2 > 10:1, UF5 is precipitated rapidly from solution, I2+ being oxidised further, apparently to IF5. With a smaller UF6:I2 mole ratio UF5 is contaminated by I2, the latter is presumed to result from the disproportion-ation of an II or IIII fluoride.β-UF5 is very soluble in acetonitrile and reacts with thallium(I) fluoride in this solvent to give TlIUF6. It reacts with trimethyl(methoxo)silane to give (CH3)3SiF, U(OCH3)5, and an insoluble solid, believed to be a mixture of UV methoxide, fluorides. Both reactions are conveniently followed by near i.r. spectroscopy. 相似文献
16.
N. A. Sharp 《General Relativity and Gravitation》1979,10(8):659-670
We give the equations governing trajectories in black hole space-times, and present a guide to the literature-a who did what annotated reference list. 相似文献
17.
18.
A. G. Pittman D. L. Sharp R. E. Lundin 《Journal of polymer science. Part A, Polymer chemistry》1966,4(10):2637-2647
The preparation and physical properties of some perhaloalkyl acrylate and methacrylate esters are discussed. In the synthetic route to the perhaloalkyl esters, acryloyl or methacryloyl chloride is made to react with a metal fluoride—perhaloketone adduct. A side reaction which accompanies esterification is the formation of acryloyl or methacryloyl fluoride. Possible mechanisms for the formation of acyl fluoride and ester are considered. Evidence is presented which suggests that acyl fluoride formation may occur by a breakdown of the fluoroalkyl esters through an intramolecular fluorine shift. 相似文献
19.
20.
The pK(a) values in DMSO of the monoprotic complexes [(L(2)Pt)(2)(mu-OH)(mu-NMePh)](2+) (4) (L(2) = Ph(2)PCH(2)CH(2)PPh(2) (dppe), Ph(2)PCMe(2)PPh(2) (dppip)) are 11.9 +/- 0.1 (L(2) = dppe) and 13.5 +/- 0.2 (L(2) = dppip) as determined by (31)P NMR equilibrium titration with bases of known pK(a). Complexes 4 were prepared by treatment of [L(2)Pt(mu-OH)](2)(2+) (1) with N-methylaniline. The oxo complexes [(L(2)Pt)(2)(mu-O)(mu-NMePh)](+), formed in the equilibrium titration reactions, were independently synthesized in THF by deprotonation of [(L(2)Pt)(2)(mu-OH)(mu-NMePh)](2+) with NaN(SiMe(3))(2) and characterized as NaBF(4) adducts. Similar experiments with diprotic [L(2)Pt(mu-OH)](2)(2+) (L(2) = dppe, Ph(2)PCH(2)CH(2)CH(2)PPh(2) (dppp)) were complicated by exchange processes and were less conclusive, giving pK(a1) < 18 and pK(a2) > 18 in DMSO. 相似文献