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21.
Jacques Piette Claire-M. Calberg-Bacq Albert van de Vorst 《Photochemistry and photobiology》1977,26(4):377-382
Abstract. Thiols and disulfides protect both φX174 phage and its isolated DNA from the lethal action of proflavine plus light. The protective ability of these compounds appears to be attributed to the -SH or the -S-S- group and the property to interact with the proflavine-phage DNA complex. The phage inactivation efficiency per proflavine bound to DNA is reduced by 50 to 30% upon addition of cysteine or cystamine. Substances that affect the lifetime of singlet oxygen modify the rate of phage photoinactivation in the presence of proflavine; the inactivation rate is decreased by N- 3 and increased by D2 O. Irradiation under N2 atmosphere markedly decreases the phage photosensitization by proflavine. Irradiation with monochromatic light of 440 nm is less efficient than irradiation with light of 440 nm plus 360 nm, and the difference is more pronounced in N2 than in air. These results are discussed in relation to various possible photochemical pathways. 相似文献
22.
The Reaction of Norbornene with Lead Tetraacetate and Thallium Trinitrate. Preliminary communication
Jacques Kagan 《Helvetica chimica acta》1972,55(7):2356-2359
The reaction of norbornene with lead tetraacetate is found to be much more complex than previously reported. In acetic acid and in benzene, the syn-7-norbornenyl, 3-nortricyclyl, and syn and anti-7-acetoxy-exo-2-norbornyl acetates were characterized. In methanol, the isolated products represented most of those expected from the competition of methanol and acetate in the neutralization of the intermediate carbocations. The reaction of norbornene with thallium trinitrate in the above solvents yielded very complex mixtures besides the above mentioned products which were formed in about 50% yield. 相似文献
23.
Analytical solutions of the diffusion equations to obtain the diffusant concentrations in the macro- and micropores which constitute the pore system of a zeolite bed are presented. The parameter which determines the influence of each pore type on the evolution of the adsorbate/adsorbant system towards the equilibrium state is described. Examples are given to illustrate a qualitative and quantitative study based on the curves obtained from these equations. 相似文献
24.
Résumé Tout d'abord, on montre par RPE que le radical CH2=-CN possède à basse température une structure instable pliée et à température plus élevée une structure stable linéaire. Un calcul théorique sur ce radical ainsi que sur le radical butatriényle est en bon accord avec les résultats expérimentaux.
The structure of the Cyano-Vinyl Radical CH2=-CN experimental and theoretical study
First, it is shown by ESR that the radical CH2=-CN at low temperature presents an unstable bent structure and at higher temperature a stable linear structure. A theoretical calculation on this radical and on the butatrienyl one is in good agreement with the experimental results.
Zusammenfassung Aus ESR Messungen wird gefolgert, daß das Radikal CH2=-CN bei tiefer Temperatur in einer instabilen gebogenen Struktur und bei höherer Temperatur in einer stabilen linearen Struktur vorliegt. Theoretische Berechnungen stehen sowohl für dieses als auch für das Butatrienyl-Radikal in guter Übereinstimmung mit experimentellen Daten.相似文献
25.
Jacqueline Ficini Jean dAngelo Arnaud Eman Anne Marie Touzin 《Tetrahedron letters》1976,17(9):683-686
26.
Christians Ferradini Jacques Foos Chantal Houee Jacques Pucheault 《Photochemistry and photobiology》1978,28(4-5):697-700
Abstract— In order to obtain a better understanding of the kinetics of the Haber-Weiss reaction
often proposed as a source of OH radicals, we have measured the decomposition rate of H2 O2 in aqueous solutions by y rays and for different pH values. This decomposition proceeds by a chain reaction involving the preceding one as the propagating step.
The rate constant found is to be
相似文献
often proposed as a source of OH radicals, we have measured the decomposition rate of H
The rate constant found is to be
相似文献
27.
H. B. Maghrawy E. Ayoub S. A. Marie 《Journal of Radioanalytical and Nuclear Chemistry》1988,121(2):429-440
The extraction of Pa(V) from 1M perchloric acid medium with HDEHP in toluene was carried out. The different factors affecting the metal distribution coefficient such as HDEHP concentration in the organic phase, pH of the aqueous phase and the equilibrium temperature were followed. From the data obtained the equilibrium constants of the extraction reaction were calculated. From the temperature variation, the corresponding thermodynamic parameters (G, H and S) were also derived. In the same way, the effect of addition of some N-and 0-containing solvents such as pyridine, 2,2-dipyridyl, n-amyl alcohol, n-decyl alcohol and n-butyl acetate, to the HDEHP organic phase was demonstrated. From the data obtained the suggested mechanisms for the synergistic extraction reactions were discussed together with the corresponding values of the thermodynamic parameters. 相似文献
28.
The symmetric and unsymmetric phenylchlorohydrodigermanes can be isolated or characterized via partial halogenation of the Ge? H bonds of the symmetrical phenylhydrodigermanes Ph2(H)GeGe(H)2Ph, Ph(H)2GeGe(H)2Ph by chloromethyl methyl ether and carbontetrachloride. Some of these phenylchlorohydrodigermanes are formed by insertion of phenylchlorogermylene (PhGeCl) on the Ge? H or Ge? Cl bonds of the phenylchlorohydrogermanes. The hydrolysis of the monochloro phenylhydrodigermanes Ph2(Cl)GeGe(H)2 and Ph(Cl)(H)GeGe(H)2Ph leads to the phenyl phenylhydrogermyl digermoxanes [Ph2(H)GeGePh2]2O and [Ph(H)2GeGe(H)Ph]2O. Treatment of these oxides with the concentrated aqueous solutions of hydracides leads to the monofluorinated, brominated and iodinated phenylhydrodigermanes Ph2(H)GeGe(X)Ph2 and Ph(H)2GeGe(H)(X)Ph (X) = F, Br, I). Phenylchlorohydrodigermanes decompose thermally by α-elimination on one germanium atom with formation of germylene and phenylchlorohydrogermane. The physico-chemical IR. and NMR. study of these phenylhalogenohydrodigermanes indicates that, if the vGe? H frequency variations are mostly linked to the inductive effects of the substituents on the same germanium, the variations of the chemical shifts of the Ge? H protons seem to be due to many factors and especially to the inductive effect of the substituents on the germanium and the magnetic anisotropy of the Ge? X bonds. 相似文献
29.
Ab initio SCF computations on the intrinsic preferences of the H+, CH
3
+
and C2H
5
+
cations towards the two principal sites of protonation or alkylation on cytosine, N3 or O2, show that this preference undergoes a continuous modification with the increase in size and complexity of the cation. N3 is the preferred site of fixation of H+, O2 the preferred site of C2H
5
+
, while CH
3
+
has no marked preference. The exchange repulsion term of the binding energy appears responsible for the preference of C2H
5
+
for O2.This work was supported by the Ligue Francaise contre le Cancer and the National Foundation for Cancer Research (USA) 相似文献
30.
Jacques Dubac Pierre Mazerolles Pierre Fagoaga 《Journal of organometallic chemistry》1977,139(3):271-277
The reaction of organomagnesium organolithium compounds (alkyl, aryl, allyl and benzyl derivatives) with 1,2-dimethyl-1-alkoxy-l-silacyclobutanes proceeds with retention of configuration at the silicon atom. Stereochemical results are discussed in terms of the SN2Si mechanism. The proposed configurations are supported by 1H and 13C NMR data. 相似文献