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931.
The structural evolution of a maize flour was followed by means of oscillatory shear measurements during heating at a rate of 10 °C/min in presence of water. These measurements were performed in a special plate and plate vessel designed to prevent moisture loss. The phenomena of gelatinization and gelation were clearly identified and their connection with the moisture content also demonstrated. Moreover, the complex mechanisms involved in gelatinization and gelation in native starch were separated. Softening of the amylose zones, exchange of water and amylose within the starch granules followed by amylopectin melting leads to the gelation of starch.  相似文献   
932.
Csáki et al.(5) have given strong approximations of continuous additive functional of Brownian motion. We establish here an extension of these results for a large class of Markov processes.  相似文献   
933.
This Note proposes a new methodology for function classification with Support Vector Machine (SVM). Rather than relying on projection on a truncated Hilbert basis as in our previous work, we use an implicit spline interpolation that allows us to compute SVM on the derivatives of the studied functions. To that end, we propose a kernel defined directly on the discretizations of the observed functions. We show that this method is universally consistent. To cite this article: N. Villa, F. Rossi, C. R. Acad. Sci. Paris, Ser. I 343 (2006).  相似文献   
934.
A rapid convergent synthesis of first- and second-generation halogenated linear poly(arylpropargyl ether) branches 7 and 10 is described. The key step of the sequence studied involves a selective Sonogashira–Linstrumelle (S–L) cross-coupling reaction of aryl iodides with alkynes bearing an sp2-carbon–iodine bond. Application to the synthesis of functionalized first-generation poly(arylpropargylether) stars having a benzene-1,3,5-tricarboxylic acid core has been realized.  相似文献   
935.
The effect of the interactions generated by the spacer group between the TTF core and the four triethoxysilane groups on the auto-organization of the organic bridging moieties in hybrid materials obtained by sol-gel chemistry has been investigated. The silica-based hybrid solids are highly polycondensed. They present different scales of organization (nanometric and micrometric) that are independent one from each other and are governed by the different parameters which control the kinetics of polycondensation. Their anisotropic organization is function of the interaction forces induced by the spacer, van der Waals, hydrogen bonding or both, during the hydrolytic condensation process.  相似文献   
936.
937.
Three boron diketonate chromophores with extended π‐conjugated backbone were prepared and their spectroscopic features were investigated through a combined theoretical/experimental study. It was shown that these complexes, which undergo very large electronic reorganization upon photoexcitation, combine large two‐photon absorption cross section with an emission energy and quantum efficiency in solution that is strongly dependent on solvent polarity. The strong positive influence of boron complexation on the magnitude of the two‐photon absorption was clearly established, and it was shown that the two‐photon absorption properties were dominated by the quadrupolar term. For one of the synthesized compounds, intense one‐ and two‐photon‐induced solid‐state emission (fluorescence quantum yield of 0.65 with maximum wavelength of 610 nm) was obtained as a result of antiparallel J‐aggregate crystal packing.  相似文献   
938.
A new stable heterocyclic germylene, in which the divalent germanium atom lies between a nitrogen atom and a phosphanylidene phosphorane group, was synthesized. Experimental and theoretical studies revealed the peculiar effect of phosphanylidene phosphorane substituent, which is a stronger π‐donor towards germanium than an amino group is. Because of the weak phosphorus–germanium π‐bond, this new germylene compound shows an enhanced reactivity compared to classical N‐heterocyclic germylenes.  相似文献   
939.
A ring carbo‐mer of naphthalene, C32Ar8 (Ar=pn‐pentylphenyl), has been obtained as a stable blue chromophore, after a 19‐step synthetic route involving methods inspired from those used in the synthesis of carbo‐benzenes, or specifically devised for the present target, like a double Sonogashira‐type coupling reaction. The last step is a SnCl2/HCl‐mediated reduction of a decaoxy‐carbo‐decalin, which is prepared through successive [8+10] macrocyclization steps. Two carbo‐benzene references are also described, C18Ar6 and o‐C18Ar4(C≡C‐SiiPr3)2. The carbo‐naphthalene bicycle is locally aromatic according to structural and magnetic criteria, as revealed by strong diatropic ring current effects on the deshielding of 1H nuclei of the Ar groups and on the negative value of the DFT‐calculated NICS at the center of the C18 rings (?12.8 ppm). The stability and aromaticity of this smallest fused molecular fragment of α‐graphyne allows prediction of the same properties for the carbon allotrope itself.  相似文献   
940.
A donor‐stabilized 1,3‐disila‐2,4‐diazacyclobutadiene presents an exceptionally short nonbonded Si???Si distance (2.23 Å), which is as short as that of Si=Si bonds (2.15–2.23 Å). Theoretical investigations indicate that there is no bond between the two silicon atoms, and that the unusual geometry can be related to a significant coulomb repulsion between the two ring nitrogen atoms. This chemical pressure phenomenon could provide an alternative and superior way of squeezing out van der Waals space in highly strained structures, as compared to the classical physical methods.  相似文献   
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