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91.
The iron(II) complex of H2L (H2L=3, 14‐dimethyl‐4, 7, 10, 13‐tetraazahexadeca‐3,13‐diene‐2,15‐dione dioxime, Coord. Chem. Rev., 33, 87 (1980)) is oxidized by periodate very rapidly in the range pH 2.0–7.0, and the kinetics of the reaction has been followed by stopped‐flow spectrophotometry at 30°C and ionic strength I=0.20 mol L−1 (NaClO4). The reaction is found to follow a simple second‐order kinetics as −d/dt [FeII(H2L)2+]=k [FeII(H2L)2+] [I(VII)], giving [FeIII(L)]+ and IO3− as the final products. The reaction has been proposed to occur through a H‐bonded transition state formed probably between the protonated oxime group of the ligand and the oxygen atom on the periodate species, followed by an electron transfer from FeII centre to IVII in a rate‐determining step. The IVI species thus generated reacts in a fast step with another FeII complex. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 23–28, 1999 相似文献
92.
We present simple and accurate analytical expressions for the evaluation of splice loss in single-mode graded index fibres. Our analysis is based on simple series expression for fundamental mode of such fibres which we have developed recently. Since splices are highly tolerant for longitudinal separation, we restrict our analysis to cases of transverse offset and angular tilt only. The concerned calculations require much less computations. With examples of step and parabolic index fibres, we show that our predictions agree excellently with the exact results. A useful collection of integration and differentiation formulae involving Bessel functions is presented in the appendix for ready reference to engineering problems of similar computational context. 相似文献
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94.
95.
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97.
Dey Sukalpa Banerjee Pradyot Gangopadhyay Sumana Vojtíšek Pavel 《Transition Metal Chemistry》2003,28(7):765-771
The synthesis of six mononuclear palladium complexes of general formula [Pd(ox)/(mal)L2] and [Pd(ox)/(mal)L] (ox = oxalate, mal = malonate, both L and L are vitamin-B6 molecules (I), L = pyridoxine, pyridoxal and L = pyridoxamine) has been achieved. The structures of these compounds were established by elemental analysis, i.r. and 13C-n.m.r. [Pd(oxalate)(pyridoxine)2] was analyzed by single crystal X-ray diffraction. It exhibits square planar coordination with bond lengths 2.015 (2) Å for Pd—N and 2.010 (2) Å for Pd—O. The interaction of [Pd(ox)2]2– and [Pd(mal)2]2– with L has been followed kinetically in order to look into the nature of products and the mechanism of formation under the conditions [PdII-chelate] [L] and [L]. 相似文献
98.
The cross section for charge transfer in He+He(23S) collisions is calculated using the asymptotic theory of ion-atom interactions, including the effects of polarization and momentum transfer. The results agree well with recent measurements by the merged beam technique. 相似文献
99.
Ali Mahammad Shames Alexander I. Gangopadhyay Sumana Saha Basudeb Meyerstein Dan 《Transition Metal Chemistry》2004,29(5):463-470
The e.p.r. studies of AgII complexes of three tetraazamacrocycles, 1,4,8,11-tetraazacyclo-tetradecane (cyclam)(I), 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclo-teradecane-4,11-diene (Me6CD)(II) and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclo-teradecane (Me6Cy)(III) and the electron transfer between [AgII(cyclam)]2+ and thiosulfate ion are described. The e.p.r. studies reveal that the spectra are almost the same as those reported earlier, particularly, for polycrystalline material and are typical of a d
9 planar AgII complexes. Previous e.p.r. studies on these square planar polycrystalline complexes showed no ligand hyperfine splitting. Reinvestigation of the e.p.r. spectra of these complexes in both the solid state and in solution at room (T 297 K) and at low (T= 120 K) temperature reveals resolved hyperfine structures in solution for [Ag(Me6CD)]2+ and [Ag(Me6Cy)]2+ complexes. Surprisingly, such a structure was not observed in solutions of [Ag(cyclam)]2+. Computer simulations of the hyperfine structure observed in solutions are in good agreement with structural formulae proposed. The oxidation of thiosulfate ion by [Ag(cyclam)]2+ follows the rate law:–d/dt[AgII(cyclam)2+]=(k
1
Q
1[H+]+k
2
Q
2
K
a2)/([H+]+K
a2)[AgII(cyclam)2+][S2O3
2–] and an inner-sphere mechanism is proposed, based on the spectral and kinetic evidence. 相似文献
100.
Summary Kinetics of the dissociation ofm-phenylene-dibiguanidecopper(II) ion,N-salicylideneglycyl-glycinatocuprate(II) ion andN-salicylideneglycinato-aquocopper(II) in acid media, forming aquo-copper(II) ion, have been studied by the stopped-flow spectrophotometric technique. Dissociation of the complexes occurs in two consecutive steps, the first being faster than the second. For them-phenylenedibiguanide complex each step exhibits second order acid dependance,k
x=k
x
[H+]2 wherek
x is the observed pseudo-first order rate constant. However, the Schiff base complexes show first order acid dependance,k
x=k
x
[H+], for both steps. The results, with relatively low H
and highly negative S
values, are consistent with a solvent-assisted dissociative process. 相似文献