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111.
Gregg BT Golden KC Quinn JF Tymoshenko DO Earley WG Maynard DA Razzano DA Rennells WM Butcher J 《Journal of combinatorial chemistry》2007,9(6):1036-1040
An efficient and rapid solution phase combinatorial synthesis of a 3-substituted 5-arylidene-1-methyl-2-thiohydantoin library was developed. The salient feature for this library production procedure is the addition of the Lewis acid catalyst, indium(III) trifluoromethanesulfonate, which serves to facilitate the direct condensation of aldehydes with 3-substituted 1-methyl-2-thiohydantoins. Use of this Lewis acid catalyst has resulted in faster reaction times, higher conversions and better purity profiles for these condensation reactions as compared to traditional uncatalyzed reactions. The resulting 315 member library of 3-substituted 5-arylidene-1-methyl-2-thiohydantoin is described. 相似文献
112.
Bailey-Shaw YA Golden KD Pearson AG Porter RB 《Journal of chromatographic science》2012,50(8):666-672
This paper describes the determination of fatty acid composition of coffee, citrus and rum distillery wastes using reversed-phase high-performance liquid chromatography (RP-HPLC). Lipid extracts of the waste samples are derivatized with phenacyl bromide and their phenacyl esters are separated on a C8 reversed-phase column by using continuous gradient elution with water and acetonitrile. The presence of saturated and unsaturated fatty acids in quantifiable amounts in the examined wastes, as well as the high percentage recoveries, are clear indications that these wastes have potential value as inexpensive sources of lipids. The HPLC procedures described here could be adopted for further analysis of materials of this nature. 相似文献
113.
This work presents the first direct experimental study of the rate constant for the reaction of OH with iso-butanol (2-methyl-1-propanol) at temperatures from 907 to 1147 K at near-atmospheric pressures. OH time-histories were measured behind reflected shock waves using a narrow-linewidth laser absorption method during reactions of dilute mixtures of tert-butylhydroperoxide (as a fast source of OH) with iso-butanol in excess. The title reaction's overall rate constant (OH + iso-butanol →(k(overall)) all products) minus the rate constant for the β-radical-producing channel (OH + iso-butanol →(k(β)) 1-hydroxy-2-methyl-prop-2-yl radical + H(2)O) was determined from the pseudo-first-order rate of OH decay. A two-parameter Arrhenius fit of the experimentally determined rate constant in the current temperature range yields the expression (k(overall) - k(β)) = 1.84 × 10(-10) exp(-2350/T[K]) cm(3) molecule(-1) s(-1). A recommendation for the overall rate constant, including k(β), is made, and comparisons of the results to rate constant recommendations from the literature are discussed. 相似文献
114.
Brian T. Gregg Kathryn C. Golden John F. Quinn Hong-Jun Wang Wei Zhang Ruifang Wang Francis Wekesa Dmytro O. Tymoshenko 《Tetrahedron letters》2009,50(27):3978-4013
A series of α,α-disubstituted amines have been prepared in a simple and efficient one-pot procedure by the addition of Grignard reagents to a series of aliphatic, aromatic, and heteroaromatic nitriles. Key to this reported procedure is the unprecedented addition of the Grignard reagent to the nitrile under heating by microwave irradiation which both significantly improves reaction yields and reduces reaction times. In general, the Grignard addition reaction is complete within 5-10 min at 100 °C followed by rapid reduction with sodium borohydride to give the target amines. 相似文献
115.
Mans A Santoso I Huang Y Siu WK Tavaddod S Arpiainen V Lindroos M Berger H Strocov VN Shi M Patthey L Golden MS 《Physical review letters》2006,96(10):107007
By combining surprising new results from a full polarization analysis of nodal angle-resolved photoemission data from pristine and modulation-free Bi(2)Sr(2)CaCu(2)O(8+delta) with structural information from LEED and ab initio one-step photoemission simulations, we prove that the shadow Fermi surface in these systems is of structural origin, being due to orthorhombic distortions from tetragonal symmetry present both in surface and bulk. Consequently, one of the longest standing open issues in the investigation of the Fermi surface of these widely studied systems finally meets its resolution. 相似文献
116.
Kenneth I. Golden 《理论物理通讯》1982,1(6):793-796
The author analyzes the effective potential of a strongly coupled one-component plasma and shows that beyond a critical value yc~10 of the plasma parameter, the liquid state is characterized by the predominance of attraction between like charges as mediated by the medium. A new exact long wavelength expression is derived for the three-point structure function. 相似文献
117.
Absolute rate constants at room temperature for the metathesis reaction have been measured under VLPP conditions: k1 = (2.0 ± 0.5) × 108M?1·s?1, k2 = (3.0 ± 0.7) × 108M?1·s?1. The radicals were generated through collisionless infrared-multiphoton decomposition of the corresponding iodides by irradiation from a high-power CO2-TEA laser. The reaction of ?2F5 and ?3F7 with \documentclass{article}\pagestyle{empty}\begin{document}$$\mathop {\rm N}\limits^{\rm .} {\rm O}_{\rm 2} $$\end{document} are briefly discussed in relation to the reaction of ?3 with \documentclass{article}\pagestyle{empty}\begin{document}$$\mathop {\rm N}\limits^{\rm .} {\rm O}_{\rm 2} $$\end{document}, which had been measured previously. 相似文献
118.
Abstract— The irreversible photochemical fading of fluorescence of acridine orange-heparin complexes indicates that fading involves the reaction of a "reactive" excited bound dye dimer with one in the ground state. A kinetic parameter, r ", is derived, which has a constant value over a considerable range of conditions, and which is directly related to rate constants for photophysical and photochemical processes. This parameter appears to be characteristic for heparin and may serve to identify it in the presence of other glycosaminoglycans. 相似文献
119.
The kinetics of the gas-phase dehydrogenation of cyclopentane to cyclopentene is found to be consistent with a slow attack by an I atom (step 4, text) on cyclopentane in the range 282–382°C. The measured rate constants fit the Arrhenius equation, log k4 = 11.95 ± 0.08 – (24.9 ± 0.23)/θ 1 mole?1 sec?1, where θ = 2.303 R T in kcal/mole. This leads to a value of ΔH = 24.3 ± 1 kcal/mole and a bond dissociation energy DH = 94.9 ± 1 kcal/mole. The latter value is identical with DH0(i-Pr-H) = 95 ± 1 kcal/mole and signifies that cyclopentane and the cyclopentyl radical have the same strain energy. Arrhenius parameters are deduced for all six steps in the reaction mechanism. Surface reactions are shown to be unimportant. Cyclopentyl iodide is an unstable intermediate in the reaction and the rate constant for its bimolecular formation from HI + cyclopentene is found to be log k6 = 8.40 ± 0.29 - (26.9 ± 0.8)/θ 1 mole?1 sec?1. Together with the equilibrium constant, this yields for the unimolecular elimination of HI from cyclopentyl iodide, the rate constant, log k5 = 13.3 ± 0.3 – (42.8 ± 1.2)/θ sec?1. 相似文献
120.