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91.
92.
Ian A. Blair Alan R. Boobis Donald S. Davies Terry M. Cresp 《Tetrahedron letters》1980,21(51):4947-4950
A convenient synthesis of N-acetyl-p-benzoquinoneimine is described, its reaction with glutathione and N-acetyl cysteine proceeds not only by adduct formation but also by a reductive pathway. 相似文献
93.
A laser-induced fluorescence excitation and resolved emission spectrum of the radical cation of 1,3,5-hexatriene has been observed in a Ne matrix. Analysis of these spectra yield vibrational frequencies for both the ground and excited states of the ion. Observations are reported concerning the photoionization process, emission quantum yield, and ion fragmentation. Matrix site effects and production in the gas phase are also discussed. 相似文献
94.
Metastable He2 molecules are produced by a dc discharge in a flowing He stream. Laser excitation downstream of the discharge produces excitation spectra for a number of He2 states. LIF spectra are observed for the series for n = 4–9, excepting 5 and the series for n = 5–15. 相似文献
95.
Peter Danziger Peter Dukes Terry Griggs Eric Mendelsohn 《Graphs and Combinatorics》2006,22(3):311-329
A Steiner triple system of order v, or STS(v), is a pair (V, ) with V a set of v points and a set of 3-subsets of V called blocks or triples, such that every pair of distinct elements of V occurs in exactly one triple. The intersection problem for STS is to determine the possible numbers of blocks common to two Steiner triple systems STS(u), (U, ), and STS(v), (V, ), with U⊆V. The case where U=V was solved by Lindner and Rosa in 1975. Here, we let U⊂V and completely solve this question for v−u=2,4 and for v≥2u−3.
supported by NSERC research grant #OGP0170220.
supported by NSERC postdoctoral fellowship.
supported by NSERC research grant #OGP007621. 相似文献
96.
Mike J. Grannell Terry S. Griggs Anne Penfold Street 《Designs, Codes and Cryptography》2006,40(2):225-236
It is shown that in some cases it is possible to reconstruct a block design
uniquely from incomplete knowledge of a minimal defining set for
. This surprising result has implications for the use of minimal defining sets in secret sharing schemes. 相似文献
97.
Fridgen TD Macaleese L McMahon TB Lemaire J Maitre P 《Physical chemistry chemical physics : PCCP》2006,8(8):955-966
The infrared multiphoton dissociation (IRMPD) spectra of three homogenous proton-bound dimers are presented and the major features are assigned based on comparisons with the neutral alcohol and with density functional theory calculations. As well, the IRMPD spectra of protonated propanol and the propanol/water proton-bound dimer (or singly hydrated protonated propanol) are presented and analysed. Two primary IRMPD photoproducts were observed for each of the alcohol proton bound dimers and were found to vary with the frequency of the radiation impinging upon the ions. For example, when the proton-bound dimer absorbs weakly a larger amount of S(N)2 product, protonated ether and water, are observed. When the proton-bound dimer absorbs more strongly, an increase in the simple dissociation product, protonated alcohol and neutral alcohol, is observed. With the aid of RRKM calculations this frequency dependence of the branching ratio is explained by assuming that photon absorption is faster than dissociation for these species and that only a few photons extra are necessary to make the higher-energy dissociation channel (simple cleavage) competitive with the lower energy (S(N)2) reaction channel. 相似文献
98.
Initial spectral results are reported from a newly constructed cavity ringdown spectrometer. The apparatus incorporates a slit-jet expansion, with or without a discharge, to produce cold sample molecules. High spectral resolution in both the near- and mid-IR is obtained by using stimulated Raman scattering of the pulsed amplified output of a cw Ti:Sa ring laser. Molecular spectra presented include the electronic near-IR transitions a (1)Delta(g)(-)<-- X (3)Sigma(g)(-) of O(2) and B (3)Pi(g)<-- A (3)Sigma(u)(+) of metastable N(2) and vibrational overtones of H(2)O (polyad 2) and the OH radical. Fundamental vibrational transitions of CH(3) (nu(3)) in the mid-IR are also observed. This apparatus has demonstrated the potential for obtaining high-resolution spectra of both reactive and non-reactive species throughout the entire IR region. 相似文献
99.
The technique of pulsed laser photolysis was coupled to laser induced fluorescence detection of iodine oxide (IO) to measure rate coefficients, k for the reactions IO + CH(3)O(2)--> products (R1, 30-318 Torr N(2)), IO + CF(3)O(2)--> products (R2, 70-80 Torr N(2)), and IO + O(3)--> OIO + O(2) (R3a). Values of k(1) = (2 +/- 1) x 10(-12) cm(3) molecule(-1) s(-1), k(2) = (3.6 +/- 0.8) x 10(-11) cm(3) molecule(-1) s(-1), and k(3a) <5 x 10(-16) cm(3) molecule(-1) s(-1) were obtained at T = 298 K. In the course of this work, the product yield of IO from the reaction of CH(3)O(2) with I was determined to be close to zero, whereas CH(3)OOI was formed efficiently at 70 Torr N(2). Similarly, no evidence was found for IO formation in the CF(3)O(2) + I reaction. An estimate of the rate coefficients k(CH(3)O(2) + I) = 2 x 10(-11) cm(3) molecule(-1) s(-1) and k(CH(3)OOI + I) = 1.5 x 10(-10) cm(3) molecule(-1) s(-1) was also obtained. The results on k(1)-k(3) are compared to the limited number of previous investigations and the implications for the chemistry of the marine boundary layer are briefly discussed. 相似文献
100.
Filby MH Humphries TD Turner DR Kataky R Kruusma J Steed JW 《Chemical communications (Cambridge, England)》2006,(2):156-158
Two types of calix[4]arene derived hosts for anions with, respectively, 1,3-alternate and cone conformations have been prepared; the 1,3-alternate system binds dicarboxylate anions in a ditopic manner while the cone compounds are deprotonated by carboxylates. 相似文献