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641.
Larry W. Eudy Michael D. Walla Joseph R. Hudson Stephen L. Morgan Alvin Fox 《Journal of Analytical and Applied Pyrolysis》1985,7(3):231-247
Fused-silica capillary gas chromatography—mass spectrometry was employed to investigate the production of several bacterial pyrolysis products, including acetamide, propionamide, and furfuryl alcohol. A variety of model compounds, selected for their similarity with bacterial structures, were pyrolyzed and amounts of these pyrolysis products were quantitatively determined. Model compounds included several analogues of muramyl dipeptide differing in chain length at the lactyl—peptide bridge as well as several neutral and amino sugars, amino acids, and nucleic acids. Bacterial cell walls and whole microbial cells were also analyzed. Measurement of the amounts of a few chemically identified pyrolysis products provides some chemotaxonomic differentiation of microorganisms, as demonstrated by the pyrolysis of a group of Gram-positive and Gram-negative bacteria (including samples of Legionella pneumophila), and fungi. 相似文献
642.
Stuart C. Clough John T. Gupton David R. Driscoll Katherine A. Griffin Alisa M. Hewitt Matthew S. Hudson S. Adepeju Ligali Seann P. Mulcahy Matthew N. Roberts Robert B. Miller Tsegahiwot T. Belachew Ivanka D. Kamenova René P.F. Kanters Bradley K. Norwood 《Tetrahedron》2004,60(45):10165-10169
Convenient routes from (Z)-3-aryl-3-chloroenals to (2E,4Z)-5-aryl-5-chloro-2,4-pentadienoates and (2E)-5-aryl-2-penten-4-ynoates are described. The stereochemical assignments are based on NMR spectral data. 相似文献
643.
J. B. Hudson E. A. Graham N. Micki L. Hudson G. H. N. Towers 《Photochemistry and photobiology》1986,44(4):477-482
The naturally occurring thiophene, α-terthienyl, was investigated for phototoxicity against several viruses and a line of mouse cells. The compound was extremely phototoxic to the two-membrane-containing animal viruses, murine cytomegalovirus (MCMV) and Sindbis virus (SV). Antiviral activity was detected at 105 μg/m in the presence of UVA. However, no effect was seen in the absence of UV-A, even at 0.1 μg/m of αT. Mouse cells were much more resistant to αT, as was the bacterial virus T4, which does not contain a membrane. Murine CMV, which had been inactivated by αT and UVA, penetrated mouse cells efficiently; but the viral DNA could not replicate, and late viral proteins were not made. Thus viral gene expression was inhibited in the photoinactivated virus. In order to account for all these data we suggest that αT may interact with viral proteins in addition to membrane lipids. 相似文献
644.
David J. McAdoo Charles E. Hudson Dennis N. Witiak 《Journal of mass spectrometry : JMS》1979,14(7):350-359
The losses of methyl and ethyl through the intermediacy of the [2-butanone]+˙ ion are shown to be the dominant metastable decomposition of 14 of 19 [C4H8O]+˙ ions examined. The ions that decompose via the [2-butanone]+˙ structure include ionized aldehydes, unsaturated and cyclic alcohols and enolic ions. [Cyclic ether]+˙ [cyclopropylmethanol]+˙ and [2-methyl-1-propen-1-ol]+˙ ions do not decompose through ionized 2-butanone. The rearrangements of various [C4H8O]+˙ ions the the 2-butanone ion were investigated by means of deuterium labeling. Those pathways involve up to eight steps. Ions with the oxygen on the end carbon rearrange to a common structure or mixture of structures. Those ions which ultimately rearrange to the [2-butanone]+˙ ion then undergo oxygen shifts from the terminal to the second and third carbons at about equal rates. However, this oxygen shift does not precede the losses of water and ethylene. Losses of water and ethylene were unimportant for ions with the oxygen initially on the second carbon. Ionized n-butanal and cyclobutanol, but not other [C4H8O]+˙ ions, undergo reversible hydrogen exchange between the oxygen and the terminal carbon. Rearrangement of ionized n-butanal to the [cyclobutanol]+˙ ion is postulated. 相似文献
645.
David J. McAdoo Charles E. Hudson John C. Traeger 《Journal of mass spectrometry : JMS》1988,23(11):760-764
The distonic ions HO+?CHCH2C˙H2 (1) and CH3C(?O+H)CH2C˙H2 (2) were directly generated, their decompositions characterized and their appearance energies determined by photoionization. Heats of formation derived from the appearance energies were 757 kJ mol?1 for 1 and 692 kJ mol?1 for 2. Deuterium labeling demonstrates that both ions decompose at low energies in the same ways as their isomers with the same skeletal structures, consistent with proposals that 1 and 2 are intermediates in the decompositions of those systems. Surprisingly, the values of the translational energy releases accompanying the formation of CH3CO+ and C2H5CO+ from 2 appear to be inversely proportional to the available excess energy. The 1,2-H-shift RC(?O+H)CH2C˙H2 → RC(?O+H)C˙HCH3 is compared to the corresponding, non-occurring 1,2-H-shift in alkyl free radicals. 相似文献
646.
J. B. Hudson H. Saboune Z. Abramowski G. H. N. Towers K. L. Rinehart Jr. 《Photochemistry and photobiology》1988,47(3):377-381
Abstract— Five eudistomins, β-carboline derivatives isolated from a Caribbean tunicate, were tested for phototoxicity against several viruses, bacteria, yeast, and mammalian cells. The five compounds showed varying degrees of UVA dependant phototoxicity (i.e. long wavelength UV dependant) against murine cytomegalovirus (MCMV), Sindbis virus (SV) and mouse 3T3 cells, although the relative order of potency was the same for these three organisms. Eudistomin N was the most active (approximately the same as the β-carboline, harmine), while eudistomins M and O were moderately phototoxic, and H and I had little activity. To some degree the relative phototoxicity was correlated with fewer side chain substituents. A similar relative order of phototoxic potency was seen against phage T4, but in this case the magnitude of the effect was considerably reduced, in contrast to harmine. The antibacterial and antifungal activities were not correlated with antiviral effects, and some UVA-independent activities were seen. Thus the eudistomins may possess different mechanisms of action against different organisms, depending upon the presence or absence of UVA. 相似文献
647.
The mechanisms of formation of m/z 73 ions in the mass spectrum of the ionized title compound were investigated by deuterium substitution and by examining the decompositions of metastable ions. Two routes to the [C4H9O]+ ions were found in the normal spectrum. The ethyl lost by the major pathway contains the α- and β-hydrogens and a γ-hydrogen from the butyl group. The minor route involves the loss of ethylene from the [M? H]+ ion. There were metastable peaks for losses of ethyl, ethanol and methyl from the molecular ion. The ethyl contains the α- and β-methylenes and a γ-hydrogen, while the methyl is the δ-methyl of the butyl group. The labeling data rule out a previous mechanistic proposal for the loss of ethyl and support a mechanism involving stepwise isomerization to the sec-butyl ethyl ether molecular ion. However, the metastable ion chemistries of the molecular ions from the n- and sec-butyl ethyl ethers are highly dissimilar, perhaps due to decompositions from different electronic states. The n-pentyl methyl ether ions loses both ethyl and propyl, apparently following rearrangements to the 3-pentyl and 2-pentyl ether ions. Di n-butyl and n-butyl methyl ethers also give metastable peaks for loss of methyl, ethyl and the shorter chain alcohol. 相似文献
648.
The products of the metastable decompositions of ionized ethyl formate (a) are characterized. The loss of water from a produces ·CH2CH2CO+, a rarely reported product. Loss of H appears to produce CH2=CHC(OH). The third decomposition is an unusual formation of C2H. This work demonstrates that a previous supposition that isomerization to different intermediates is involved in the losses of ethene and of water from a is correct. 相似文献
649.
650.