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21.
Kira Rubina Edgars Ābele Juris Popelis Solveiga Grinberga Pavel Arsenyan Edmunds Lukevics 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):521-529
A novel two-step method for the preparation of ( E )-2-chlorovinylthioarenes (or hetarenes) from thiols and 1,1,2-trichloroethane in the phase transfer catalytic systems solid K 2 CO 3 /solid KI/18-crown-6/xylene and solid KOH/18-crown-6/toluene has been developed. ( E )-2-chlorovinylthioarenes were isolated in yields up to 98%. Utilization of ( E )-2-chlorovinylthioarenes in the Heck and Stille reactions has been shown. 相似文献
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Prof. Dr. I. Kira Astakhova Prof. Dr. Jesper Wengel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):1112-1122
Double‐labeled oligonucleotide probes containing fluorophores interacting by energy‐transfer mechanisms are essential for modern bioanalysis, molecular diagnostics, and in vivo imaging techniques. Although bright xanthene and cyanine dyes are gaining increased prominence within these fields, little attention has thus far been paid to probes containing these dyes internally attached, a fact which is mainly due to the quite challenging synthesis of such oligonucleotide probes. Herein, by using 2′‐O‐propargyl uridine phosphoramidite and a series of xanthenes and cyanine azide derivatives, we have for the first time performed solid‐phase copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) click labeling during the automated phosphoramidite oligonucleotide synthesis followed by postsynthetic click reactions in solution. We demonstrate that our novel strategy is rapid and efficient for the preparation of novel oligonucleotide probes containing internally positioned xanthene and cyanine dye pairs and thus represents a significant step forward for the preparation of advanced fluorescent oligonucleotide probes. Furthermore, we demonstrate that the novel xanthene and cyanine labeled probes display unusual and very promising photophysical properties resulting from energy‐transfer interactions between the fluorophores controlled by nucleic acid assembly. Potential benefits of using these novel fluorescent probes within, for example, molecular diagnostics and fluorescence microscopy include: Considerable Stokes shifts (40–110 nm), quenched fluorescence of single‐stranded probes accompanied by up to 7.7‐fold light‐up effect of emission upon target DNA/RNA binding, remarkable sensitivity to single‐nucleotide mismatches, generally high fluorescence brightness values (FB up to 26), and hence low limit of target detection values (LOD down to <5 nM ). 相似文献
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Vinyl-substituted silylenes, 2,5-bis(methylene)-1-silacyclopentane-1,1-diyl ( 1 ) and 2-methylene-1-silacyclopentane-1,1-diyl ( 2 ), generated photochemically from the corresponding trisilanes in 3-methylpentane (3-MP) at 77 K, showed broad bands at 505 and 475 nm, respectively, which were assigned to the n(Si)-3p(Si) transition. The origin of the red shift in the n(Si)-3p(Si) transition is ascribed to the significant lowering of the 3p(Si) orbital level caused by the vinyl substitution on the silylene; the relatively high-lying 3p(Si) orbital can interact more effectively with the antibonding π* orbital than with the bonding π orbital of the vinyl group. The absorption spectra for 1 and 2 in the presence of several bases in 3-MP glass matrix shifted significantly to blue due to the formation of the corresponding base complexes. Analysis of the spectral change of the silylenes upon complexation with bases was very constructive for the understanding of the structural characteristics of substituted silylenes. 相似文献
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R. J. Fries 《Pramana》2010,75(2):235-245
We review some basic concepts of relativistic heavy-ion physics and discuss our understanding of some key results from the
experimental program at the relativistic heavy-ion collider (RHIC). We focus in particular on the early time dynamics of nuclear
collisions, some result from lattice QCD, hard probes and photons. 相似文献
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W. Fries W. Schwarz H.-D. Hausen J. Weidlein 《Journal of organometallic chemistry》1978,159(4):373-384
Dimethylpropynylmetal compounds of Al, Ga and In are formed in 40–60% yield by the reaction of NaCCCH3 with (CH3)2MIIIHal (MIII Al, Ga, In; Hal Cl, Br). The IR, Raman, 1H and 13C NMR spectra of these, in solution dimeric, compounds are discussed. The indium derivative crystallizes in the orthorhombic space group Pnma with 4 formula units per unit cell. The lattice parameters are a 926.9; b 578.7 and c 1216.6 pm. 相似文献
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