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21.
22.
Dominique Margelin Anny Fourtanier Thierry Thevenin Chantal Medaisko Monique Breton Jacques Picard 《Photochemistry and photobiology》1993,58(2):211-218
Abstract— The effect of UVB exposure on the distribution and synthesis of dermal proteoglycans was measured in the skin of hairless mice. Two groups of mice were included: one was irradiated for 10 weeks; the other was kept as control. After intraperitoneal injection of sodium 35 S-sulfate, punch biopsies were taken for histology and proteoglycans were extracted from the remaining skin with 4 M guanidinium chloride, containing 3–[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (0.5%, weight per volume). Following proteolytic digestion, the glycosaminoglycan constituents were isolated and analyzed by quantitative cellulose acetate electrophoresis and enzymatic digestibility.
Under the influence of UVB radiation, newly synthesized proteoglycans measured by35 SO4 uptake increased as much as 60%. In addition, the irradiated skin had a higher average content of proteoglycan than had control skin (4981 μg vs 4134 μg/g dry weight). This could be ascribed to an increase in heparin (1400 vs 533 μ g/g dry weight) and heparan sulfate (472 vs 367 μg/g dry weight), whereas no change in the concentration of hyaluronic acid (1243 vs 1372 μg/g dry weight) and dermatan sulfate (1866 vs 1863 μg/g dry weight) was observed. The irradiated animals also exhibited a marked increase in the synthesis of heparan sulfate and heparin (62% and 71%, respectively). These results demonstrate that chronic doses of UVB altered proteoglycan metabolism through both quantitative and qualitative changes. 相似文献
Under the influence of UVB radiation, newly synthesized proteoglycans measured by
23.
Mikhael Balabane Thierry Cazenave Luis Vázquez 《Communications in Mathematical Physics》1990,133(1):53-74
We prove the existence of stationary states for nonlinear Dirac equations of the form (E) $$i\sum\limits_{\mu = 0}^3 {\gamma ^\mu \partial _\mu \psi - M\psi + F\left( {\bar \psi \psi } \right)\psi = 0,} $$ whereM>0 andF is a singular self-interaction. In particular, in the model case whereF(s)=?s ?α, for some 0<α<1, and for every ω>M, there exists a solution of (E) of the form ψ(t, x)=e iωt?(x), wherex 0=t andx=(x 1,x 2,x 3), such that ? has compact support. IF 0<α<1/3, then ? is of classC 1. If 1/3<α<1, then ? is continuously differentiable, except on some sphere {|x|=R}, where |??| is infinite. 相似文献
24.
Two different 6-quark resonating group models of the deuteron are investigated to study the off-shell property of theN-N interaction. In the first model the quarks interact by a central one-gluon-exchange potential plus confinement potential. The meson-exchange contribution to then-p potential is simulated by a central GaussianN-N potential. In the second model the quarks interact by one-gluon-and one-pion-exchange potentials (central and noncentral) plus confinement potential. A small additional -exchange potential between neutron and proton binds the deuteron at the correct energy.Several off-shell variants of the two resonating group models are compared with each other by analyzing their elastic electron scattering cross sections. It is found that the standard renormalized version of the resonating group model yields potentials and wave functions that may be considered physical within the limitations of the model. Unitary off-shell transformations, which modify potentials and wave functions in any sizeable way, lead to a disagreement between the charge distribution predicted by the model via analysis of electron scattering and the charge distribution following from the microscopic quark distribution.Both of the 6-quark models support a soft repulsive core of the tripletn-p potential with a core height of around 900 MeV. 相似文献
25.
Thierry Boulanger Daniel P. Vercauteren Guy Evrard François Durant 《Journal of chemical crystallography》1987,17(5):561-573
The crystal structure of 2-(carboxy-3-propyl)-3-amino-6-cyclohexylpyridazinium bromide has been determined by single-crystal X-ray diffraction techniques and refined by full-matrix least squares. The compound crystallized in the tri-clinic space groupP ¯1 witha=10.275(1),b=11.215(1),c=7.082(1) Å,=91.84(1),=102.21(1), =106.77(1)°, andZ=2. FinalR-factor is 0.045. The main structural results are very similar to the ones observed for the 6-phenyl analog. These two compounds are GABA-A antagonists.Ab initio molecular orbital calculations, with STO-3G and 4-31G basis sets, suggest that the exocyclic nitrogen accurately mimics the nitrogen atom of GABA. 相似文献
26.
Henri-Edouard Audier Marcel Fetizon Yannik Henry Thierry Prange 《Journal of mass spectrometry : JMS》1976,11(10):1047-1055
The fragmentation mechanisms of oxazole have been studied in detail on using various experimental techniques (refocusing of metastable ions, deuteration, AP measurements) and by theoretical calculations. 相似文献
27.
7-Benz[c] acridinemethanols as tetracyclic analogs of the 2-phenyl-4-quinolinemethanol antimalarials
Andre Rosowsky Michael Chaykovsky Sandra A. Yeager Richard A. St. Amand May Lin Edward J. Modest 《Journal of heterocyclic chemistry》1971,8(5):809-820
A series of new 7-benz[c]acridinemethanols and 5,6-dihydro-7-benz[c]acridinemethanols was prepared as rigid, tetracyclic analogs of the antimalarial 2-phenyl-4-quinolinemethanols. Condensation of 5,7-dichloroisatin with 6-chloro-, 7-chloro-, and 6,7-dichloro-1-tetralone furnished halogenated 5,6-dihydro-7-benz[c]acridinecarboxylic acids, which were transformed into the corresponding acid chlorides, acyl malonates, α-bromomethyl ketones, and epoxides. Fully aromatic members of the series obtained via dehydrogenation of the 5,6-dihydro acids were likewise converted into epoxides via the acylmalonate route. Although all the epoxides studied proved to be exceptionally resistant to ring-opening by di-n-butylamine, probably on account of steric effects, they could be cleaved readily with piperidine or morpholine. Nmr spectra of the resulting amino alcohols suggest that these compounds exist in a single preferred conformation stabilized by internal O-H····N hydrogen bonding, and that free rotation about the side chain C-C bond does not occur at room temperature. 相似文献
28.
Judith Polonsky Thierry Prangé Claudine Pascard Henri Jacquemin Alain Fournet 《Tetrahedron letters》1984,25(22):2359-2362
Manicoline B, isolated from the root bark of (Olacaceae), was shown by X-ray analysis to be an equimolecular mixture of two diastereoisomers of a new alkaloid and to have structure (3). 相似文献
29.
Under Lewis acid activation, hemiaminals of trifluoroacetaldehyde and related (fluoroalkyl)aldehydes generate iminium species that can react with various nucleophiles to provide fluorinated amines. 相似文献
30.
Two new enantioselective syntheses of the naphthopyranquinone antibiotic frenolicin B ( 1 ), of its enantiomer 2 , and of its diastereoisomers 3 and 4 were accomplished using two different routes from optically active β-Hydroxy esters (R)- and (S)- 11 and 18. β-Hydroxy esters (R)- and (S)- 11 were prepared stereoselectively from optically active sulfenylacetates (S)- and (R)- 10 , respectively (Scheme 2, Method A). Alternatively, compound 18 was obtained in excellent yield by enantioselective hydrogenation of the corresponding β-keto ester 17 , using a chiral ruthenium-complex catalyst (Scheme 3, Method B). Subsequently, compounds (S)- 11 and 18 were transformed into frenolicin B (1). In analogy, Stereoisomers 2–4 were prepared from (S)- and (R)- 11 in good yields. 相似文献