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111.
Olivier C Hot D Huot L Ollivier N El-Mahdi O Gouyette C Huynh-Dinh T Gras-Masse H Lemoine Y Melnyk O 《Bioconjugate chemistry》2003,14(2):430-439
We describe in this paper the preparation and characterization of semicarbazide glass slides and their use for the fabrication of microarrays using site-specific alpha-oxo semicarbazone ligation. The functional density and homogeneity of the semicarbazide glass slides were optimized by analyzing the reactivity of the layer toward a synthetic glyoxylyl fluorescent probe. Oligonucleotide microarrays were prepared by site-specific immobilization of glyoxylyl oligodeoxynucleotides. The slides were directly used in the hybridization assays using fluorescence detection and displayed a significant gain in sensibility as compared to the aldehyde glass slide/amino oligodeoxynucleotide chemistry. Semicarbazide slides were also used for the immobilization of a biotinylated peptide alpha-oxo aldehyde. The peptide microarrays allowed model interaction studies with streptavidin or an anti-biotin antibody. 相似文献
112.
Bizat N Hermel JM Humbert S Jacquard C Créminon C Escartin C Saudou F Krajewski S Hantraye P Brouillet E 《The Journal of biological chemistry》2003,278(44):43245-43253
The role of caspases and calpains in neurodegeneration remains unclear. In this study, we focused on these proteases in a rat model of Huntington's disease using the mitochondrial toxin 3-nitropropionic acid (3NP). Results showed that 3NP-induced death of striatal neurons was preceded by cytochrome c redistribution, transient caspase-9 processing, and activation of calpain, whereas levels of the active/processed form of caspase-3 remained low and were even reduced as compared with control animals. We evidenced here that this decrease in active caspase-3 levels could be attributed to calpain activation. Several observations supported this conclusion. 1) Pharmacological blockade of calpain in 3NP-treated rats increased the levels of endogenous processed caspase-9 and caspase-3. 2) Cell-free extracts prepared from the striatum of 3NP-treated rats degraded in vitro the p34 and p20 subunits of active recombinant caspase-9 and caspase-3, respectively. 3) This degradation of p34 and p20 could be mimicked by purified mu-calpain and was prevented by calpain inhibitors. 4) mu-Calpain produced a loss of the DEVDase (Asp-Glu-Val-Asp) activity of active caspase-3. 5) Western blot analysis and experiments with 35S-radiolabeled caspase-3 showed that mu-calpain cleaved the p20 subunit of active caspase-3 near its catalytic site. 6) mu-Calpain activity was selectively inhibited (IC50 of 100 mum) by a 12 amino acid peptide corresponding to the C terminus of p20. Our results showed that calpain can down-regulate the caspase-9/caspase-3 cell death pathway during neurodegeneration due to chronic mitochondrial defects in vivo and that this effect may involve, at least in part, direct cleavage of the caspase-3 p20 subunit. 相似文献
113.
114.
Christophe Le May Michèle Guibert Aurélie Leclerc Didier Andrivon Bernard Tivoli 《Applied and environmental microbiology》2012,78(23):8431-8440
Plant diseases are caused by pathogen populations continuously subjected to evolutionary forces (genetic flow, selection, and recombination). Ascochyta blight, caused by Mycosphaerella pinodes, is one of the most damaging necrotrophic pathogens of field peas worldwide. In France, both winter and spring peas are cultivated. Although these crops overlap by about 4 months (March to June), primary Ascochyta blight infections are not synchronous on the two crops. This suggests that the disease could be due to two different M. pinodes populations, specialized on either winter or spring pea. To test this hypothesis, 144 pathogen isolates were collected in the field during the winter and spring growing seasons in Rennes (western France), and all the isolates were genotyped using amplified fragment length polymorphism (AFLP) markers. Furthermore, the pathogenicities of 33 isolates randomly chosen within the collection were tested on four pea genotypes (2 winter and 2 spring types) grown under three climatic regimes, simulating winter, late winter, and spring conditions. M. pinodes isolates from winter and spring peas were genetically polymorphic but not differentiated according to the type of cultivars. Isolates from winter pea were more pathogenic than isolates from spring pea on hosts raised under winter conditions, while isolates from spring pea were more pathogenic than those from winter pea on plants raised under spring conditions. These results show that disease developed on winter and spring peas was initiated by a single population of M. pinodes whose pathogenicity is a plastic trait modulated by the physiological status of the host plant. 相似文献
115.
K K Andersson C Dalet C Bonfils P Maurel 《Biochemical and biophysical research communications》1981,98(1):311-316
Elastase-type activities were found associated with lipoprotein fractions in human serum. A metallo-protease hydrolysing Suc(Ala)3 PNA and soluble elastin peptides was isolated from apoHDL by Sepharose-elastin chromatography. Polyacrylamide gel electrophoresis and immunoelectrophoresis indicated that this elastase-type activity was associated with apoA1. 相似文献
116.
M Deschodt-Lanckman P Robberecht J Christophe 《Archives of biochemistry and biophysics》1981,208(1):1-10
Heparin inhibited the adenylate cyclase activity of semipurified rat pancreatic plasma membranes stimulated by hormones and by Gpp(NH)p but not by fluoride or when in the persistently active state. When observed, the inhibition was rapid and sustained. It was of a noncompetitive type and never exceeded 20% for secretin. The inhibition of Gpp(NH)p-stimulated activity was more pronounced (48% inhibition at a heparin concentration of 50 μg/ml). For the C-terminal octapeptide of pancreozymin (CCK-8)-stimulated adenylate cyclase, the inhibition amounted to 93% at 50 μg/ml. This inhibition was competitive at low heparin concentration and of a mixed type above 10 μg/ml. Besides, heparin inhibited (I50 = 6 μg/ml) the binding of peptides of the CCK family to their specific receptors without affecting the apparent Kd value of binding. Taken together, these relatively specific effects of heparin gave evidence in favor of the existence of CCK spare receptors. Dextran sulfate was more potent than heparin as an inhibitor of adenylate cyclase activation while chondroitin-4-sulfate and chondroitin-6-sulfate were ineffective. Dansylated pancreatic plasma membranes exhibited characteristics of adenylate cyclase activation by CCK-8 which were similar to those found for untreated membranes exposed to heparin. 相似文献
117.
Entrapment of pollutants in Mediterranean sediments and biogeochemical indicators of their impact 总被引:1,自引:0,他引:1
The transit and fate of certain pollutants (Cd, Pb, Zn and P) transported to the western Mediterranean sea-floor and a method to assess their impact are described. The spatial distribution of pollutant concentrations in the Rhône prodelta shows that their decline with distance from their source is due both to mixing with unpolluted sediments, release from contaminated particles during transit and release from sediments after deposition. Beyond the continental shelf, metals of anthropogenic origin, mainly incorporated in faecal pellets, sink and become entrapped in deep sea sediments. Because subsaturating concentrations of trace metals are often found in surface pore waters and storage, therefore, still occurs, co-precipitation with other metal ions existing in slightly supersaturated states has also to be considered. Although phosphate tends to precipitate as apatite after entering sea water, its `definitive' storage in sediments is hindered by certain forms of pollution. Low pH and reducing conditions in sediments enhance phosphate release to the overlying water . Eutrophication may then occur in localised areas. The effects of urban waste water contamination on biogeochemical processes in sediments are examined, in particular processes responsible for the transformation of organic nitrogen. Sediment quality appears to be better defined by the effectiveness of diagenetic processes than by pollutant concentration per se. In general, polluted sediments possess weak capacities to transform organic nitrogen relative to the quantities of organic matter that are available. Such sediment characteristics are indicated by the preferential growth of Caulerpa taxifolia over that of Posidonia oceanica. 相似文献
118.
Christophe Sola Ingrid Filliol Eric Legrand Igor Mokrousov Nalin Rastogi 《Journal of molecular evolution》2001,53(6):680-689
This paper deals with phylogenetic relationships among a set of 90 clinical strains representative of the worldwide diversity
of the Mycobacterium tuberculosis complex (Kremer et al. 1999) using eight independent genetic markers: IS6110, IS1081, the direct repeat (DR) locus, and five variable number of tandem DNA repeat loci (VNTR). In a preliminary experiment, phylogenetic
trees based on single markers were constructed that led to the detection of some similarities between the VNTR-based and the
spoligotyping-based phylogenetic trees. In the second step, a more global phenetic approach based on pairwise comparison of
strains within each typing system was used, followed by calculations of mean genetic distances based on all the eight loci
and the use of the neighbor-joining algorithm for tree reconstruction. This analysis confirmed our preliminary observations
and suggested the existence of at least two new phylogeographical clades of M. tuberculosis, one defined as the ``East African–Indian family' (EA-I), which may find its origin on the African or Asian continents, and
the other as the ``Latin American and Mediterranean' (LA-M) family. The existence of these two families was also validated
by an independent phylogenetic analysis of spoligotyping on a larger set of shared types (n= 252) and further corroborated by VNTR and katG–gyrA results. The potential origin of these families of bacilli is discussed based on cattle domestication and human migration
history. In conclusion, the information contained in insertion sequence and repetitive DNAs may serve as a model for the phylogenetic
reconstruction of the M. tuberculosis complex. 相似文献
119.
Francesco Loreto Michela Mannozzi Christophe Maris Pamela Nascetti Francesco Ferranti Stefania Pasqualini 《Plant physiology》2001,126(3):993-1000
Isoprene is formed in and emitted by plants and the reason for this apparent carbon waste is still unclear. It has been proposed that isoprene stabilizes cell and particularly chloroplast thylakoid membranes. We tested if membrane stabilization or isoprene reactivity with ozone induces protection against acute ozone exposures. The reduction of visible, physiological, anatomical, and ultrastructural (chloroplast) damage shows that clones of plants sensitive to ozone and unable to emit isoprene become resistant to acute and short exposure to ozone if they are fumigated with exogenous isoprene, and that isoprene-emitting plants that are sensitive to ozone do not suffer damage when exposed to ozone. Isoprene-induced ozone resistance is associated with the maintenance of photochemical efficiency and with a low energy dissipation, as indicated by fluorescence quenching. This suggests that isoprene effectively stabilizes thylakoid membranes. However, when isoprene reacts with ozone within the leaves or in a humid atmosphere, it quenches the ozone concentration to levels that are less or non-toxic for plants. Thus, protection from ozone in plants fumigated with isoprene may be due to a direct ozone quenching rather than to an induced resistance at membrane level. Irrespective of the mechanism, isoprene is one of the most effective antioxidants in plants. 相似文献
120.
Metabolic Engineering of Ammonium Assimilation in Xylose-Fermenting Saccharomyces cerevisiae Improves Ethanol Production 总被引:2,自引:0,他引:2 下载免费PDF全文
Cofactor imbalance impedes xylose assimilation in Saccharomyces cerevisiae that has been metabolically engineered for xylose utilization. To improve cofactor use, we modified ammonia assimilation in recombinant S. cerevisiae by deleting GDH1, which encodes an NADPH-dependent glutamate dehydrogenase, and by overexpressing either GDH2, which encodes an NADH-dependent glutamate dehydrogenase, or GLT1 and GLN1, which encode the GS-GOGAT complex. Overexpression of GDH2 increased ethanol yield from 0.43 to 0.51 mol of carbon (Cmol) Cmol−1, mainly by reducing xylitol excretion by 44%. Overexpression of the GS-GOGAT complex did not improve conversion of xylose to ethanol during batch cultivation, but it increased ethanol yield by 16% in carbon-limited continuous cultivation at a low dilution rate. 相似文献