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41.
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43.
Krishnamoorthy G Webb SP Nguyen T Chowdhury PK Halder M Wills NJ Carpenter S Kraus GA Gordon MS Petrich JW 《Photochemistry and photobiology》2005,81(4):924-933
Hydroxy and methoxy perylene quinones are synthesized in an attempt to isolate the essential spectroscopic and biological features of light-induced antiviral agents such as hypericin and hypocrellin. Unlike their naturally occurring counterparts, these synthetic quinones bear the carbonyl, hydroxyl, and methoxy groups in the "bay region." The hydroxy and methoxy compounds have rich absorption spectra with broad features in the visible (approximately 450-800 nm) and relatively more intense and narrow features at wavelengths < or = 350 nm. High-level ab initio quantum mechanical calculations assign the features in the absorption spectra to electronic transitions from S0 to S2 and to higher-lying electronic states. The calculations indicate that in the ground state the trans dihydroxy isomer is 12.5 kcal/mol lower in energy than the cis dihydroxy isomer and is thus the only species present. The lowest-energy trans methoxy ground state isomer and the lowest-energy cis methoxy ground state isomer are found to be degenerate. An additional cis methoxy isomer 6.3 kcal/mol higher in energy than the global minimum is assumed to contribute to the spectrum and is also considered. Finally, the synthetic compounds exhibit similar light-induced antiviral activity to each other, but significantly less than that of hypericin. 相似文献
44.
Bharathi Alagar Muthumani Narayanan Anbalagan Krishnamoorthy 《Transition Metal Chemistry》1997,22(6):586-588
The ground- and excited-state reactivities of the [Cr- (en)3]3+ (en=1,2-diaminoethane) and [Cr(NCS)6]3− ions in a polyacrylamide
(PAA) environment are reported. The aquation kinetics of these complexes has been studied to identify the effect of added
PAA with varying molecular weight. Aquation of the complexes in aqueous acid containing PAA yielded the respective substituted
products. The macromolecule in solution was found to decrease significantly the rate of ligand replacement. Similarly, photolysis
of the cationic and anionic complexes in water–PAA mixtures revealed a decrease in aquation quantum yield. Possible explanations
for the decrease in reaction rates and quantum yields are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
45.
A rapid and highly sensitive silver staining method, originally developed for the detection of proteins, was slightly modified to detect nucleic acids in polyacrylamide gels. The second exons of the histocompatibility antigen HLA-DQA 1 and DQB 1 genes were selectively amplified from genomic DNA by the polymerase chain reaction (PCR). Digestion of the PCR products by endonucleases, followed by their size-separation on polyacrylamide gels and visualization by silver staining, allowed us to define the HLA-DQ alleles of the genomic DNA. The intensity of staining of digested PCR-amplified DNA is linear from at least 8 to 18 ng for fragments of lengths ranging from approximately 40 to 200 bp. Thus, silver staining in combination with PCR and allele-specific restriction fragment length polymorphism provides a simple, safe, and rapid method for accurate definition of HLA-DQ alleles at the nucleotide level in the clinical typing laboratory. 相似文献
46.
A complete solution is established to the problem of characterizing all situations in which a linear combination C = c
1
A+c
2
B of an idempotent matrix A and a tripotent matrix B is k-idempotent. As a special case of this, a set of necessary and sufficient conditions for a linear combination C = c
1
A+c
2
B to be k-idempotent when A and B are idempotent matrices, is also studied in this paper. 相似文献
47.
Anoop M Saxena G Krishnamoorthy Jayant B Udgaonkar N Periasamy 《Journal of Chemical Sciences》2007,119(2):61-69
In protein-folding studies it is often required to differentiate a system with only two-states, namely the native (N) and
unfolded (U) forms of the protein present at any condition of the solvent, from a situation wherein intermediate state(s)
could also be present. This differentiation of a two-state from a multi-state structural transition is non-trivial when studied
by the several steady-state spectroscopic methods that are popular in protein-folding studies. In contrast to the steady-state
methods, time-resolved fluorescence has the capability to reveal the presence of heterogeneity of structural forms due to
the ‘fingerprint’ nature of fluorescence lifetimes of various forms. In this work, we establish this method by quantitative
analysis of amplitudes associated with fluorescence lifetimes in multiexponential decays. First, we show that we can estimate,
accurately, the relative population of species from two-component mixtures of non-interacting molecules such as fluorescent
dyes, peptides and proteins. Subsequently, we demonstrate, by analysing the amplitudes of fluorescence lifetimes which are
controlled by fluorescence resonance energy transfer (FRET), that the equilibrium folding-unfolding transition of the small
single-domain protein barstar is not a two-step process. 相似文献
48.
A green synthesis of 1,2,3-triazolyl-pyridine hybrids and evaluation of their antibacterial activity
49.
50.
Carrillo LD Krishnamoorthy L Mahal LK 《Journal of the American Chemical Society》2006,128(46):14768-14769
beta-O-N-Acetyl-d-glucosamine (O-GlcNAc) is a dynamic carbohydrate modification that is involved in cell signaling and has been implicated in a variety of disease states, including Alzheimer's and type-II diabetes. Despite the importance of this modification, little is known about the spatial and temporal localization of O-GlcNAc during signaling. This is due to the lack of methods for the study of O-GlcNAc in living cell systems. Herein we report the first genetically encoded FRET-based sensor for the detection of O-GlcNAc dynamics in live mammalian cells. 相似文献