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Six very premature babies (born at 26–28 weeks gestational age) have been studied in hospital for 11–17 weeks, while in intensive care and in an incubator. Apart from suffering occasionally from the neonatal disorders of haemolytic jaundice and ‘respiratory distress of the newborn’, the babies were healthy and developed normally. Initially, the babies were continuously fed intravenously, and the lighting in the ward was on continuously. Routine care was given round the clock. When their medical condition permitted it, the babies were moved in their incubator to an adjacent ward, where they took frequent (2–4 hourly) small meals by mouth, the lighting was dimmed at night, and routine care tended to be given more in the daytime. Hourly recordings of insulated skin temperature were taken throughout the study, and it is the detection of rhythmicity in these measurements that has been the subject of the present study. The methods used were Phase-weighted Stacks, Phasor Walkout and Power Spectral Analysis. These methods have previously been used mainly in geophysical studies, and their value is that they can detect weak signals in noisy data and do not assume a particular waveform of any signal. Circadian rhythmicity was found in all babies for much of the time that were in the constant environment provided by the incubator. Ultradian rhythms were sometimes present also, but they were shorter-lived, and showed a wide range of changing periods, generally in excess of 8 h. When the babies were being treated for jaundice or respiratory distress, there was a tendency for the circadian rhythms to become weaker and for a broader spectrum of ultradian periods to appear. Placing babies in the 12 h : 12 h light : dark environment provided by the ward, and instituting feeding by mouth, had, in most cases, only modest effects upon either circadian or ultradian rhythms. Thus, circadian rhythms continued (but generally with a period not exactly equal to 24 h), and ultradian rhythms, when present, often did not show periods that could be related easily to feeding or care-giving. These results are discussed in terms of evidence for endogenous and exogenous origins of the observed rhythms, and of theories that have postulated the relationship between circadian and ultradian rhythms. It is concluded that the results from the present analyses are difficult to reconcile with the view that circadian rhythms develop from interactions between ultradian oscillators. We suggest that they indicate a matu-ration of the circadian system as a consequence of increasing associations between the circadian elements that are present in the suprachiasmatic nuclei and in other oscillators of the circadian system. The new analytical methods used here also indicate that the results obtained from time-frequency analysis depend to some extent upon the method used.  相似文献   
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Introduction  

Sj?gren's syndrome (SS) is a systemic autoimmune disease that mainly targets the exocrine glands. The aim of this study was to investigate the involvement of 87 proteins measured in serum and 75 proteins analyzed in saliva in spontaneous experimental SS. In addition, we intended to compute a model of the immunological situation representing the overt disease stage of SS.  相似文献   
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Several new HLA-B (B8, B51, Bw62)- and HLA-C (Cw6, Cw7)-specific genes were isolated either as genomic cosmid or cDNA clones to study the diversity of HLA antigens. The allele specificities were identified by sequence analysis in comparison with published HLA-B and -C sequences, by transfection experiments, and Southern and northern blot analysis using oligonucleotide probes. Comparison of the classical HLA-A, -B, and -C sequences reveals that allele-specific substitutions seem to be rare events. HLA-B51 codes only for one allelespecific residue: arginine at position 81 located on the 1 helix, pointing toward the antigen binding site. HLA-B8 contains an acidic substitution in amino acid position 9 on the first central sheet which might affect antigen binding capacity, perhaps in combination with the rare replacement at position 67 (F) on the ul helix. HLA-B8 shows greatest homology to HLA-Bw42, -Bw41, -B7, and-Bw60 antigens, all of which lack the conserved restriction sites Pst I at position 180 and Sac I at position 131. Both sites associated with amino acid replacements seem to be genetic markers of an evolutionary split of the HLA-B alleles, which is also observed in the leader sequences. HLA-Cw7 shows 98% sequence identity to the JY328 gene. In general, the HLA-C alleles display lower levels of variability in the highly polymorphic regions of the 1 and 2 domains, and have more distinct patterns of locus-specific residues in the transmembrane and cytoplasmic domains. Thus we propose a more recent origin for the HLA-C locus.  相似文献   
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Summary Mutants of Candida maltosa were isolated that lacked saccharopine reductase (lys9) and saccharopine dehydrogenase (lys1) and were able to accumulate -aminoadipate--semialdehyde (AASA) in the cell and excrete it into the culture medium. The effects of incubation time, lysine concentration, and carbon and nitrogen sources on AASA production were examined. In the presence of 15 g glucose/1, 1.25 g NH4H2PO4/l and 50 mg l-lysine/l in a minimal salt medium C. maltosa G285 (lys1) produced about 80–90 mg AASA/l during 48 h of growth. A simple and rapid procedure to isolate AASA from the medium using Dowex 50X4 is described.  相似文献   
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Coenzyme A-linked acetaldehyde dehydrogenase (ACDH) of ethanol-grown cells of Acetobacterium woodii was purified to apparent homogeneity; a 28-fold purification was achieved with 13% yield. The enzyme proved to be oxygen-sensitive and was inactive in the absence of dithioerythritol. During the purification procedure addition of 1 mM MgCl2 was necessary to maintain enzyme activity. Alcohol dehydrogenase (ADH) activity was separated from ACDH during anion exchange chromatography using DEAE Sephacel. A part of the ACDH activity coeluted with ADH, but both could be separately eluted from a Cibacron Blue 3GA-Agarose column, revealing the same subunit structure and activity band for ACDH as found before and, thus, indicating an aggregation of the enzyme. The remaining ADH activity could be separated by gel filtration. For the native ACDH a molecular mass of 255 kDa was determined by polyacrylamide gel electrophoresis and of 272 kDa by gel filtration using Superose 12. The enzyme subunit sizes were 28 kDa and 40 kDa, respectively, indicating a 44 structure for the active form. The enzyme catalyzed the oxidation of several straight chain aldehydes although it was most active with acetaldehyde. NADH strongly inhibited oxidation of acetaldehyde whereas NADPH had no effect. The inhibition was noncompetitive.Non-standard abbrevations ACDH acetaldehyde dehydrogenase - ADH alcohol dehydrogenase - CHES 2-(N-cyclohexylamino)-ethanesulfonate - DTE dithioerythritol - KP-buffer 25 mM K-PO4, pH 7.5, containing, 4 mM DTE - MES 2-(N-morpholino)-ethanesulfonate - TAPS N-Tris-(hydroxymethyl)-methyl-3-aminopropa-nesulfonate  相似文献   
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Arabidopsis thaliana lines have been isolated that are insensitive to the fungal toxin fusicoccin (FC). Initial screening was done by selecting for plants that either grew well on high concentrations of FC or did not respond to FC by increases in H+-extrusion. All selected plants were tested, in several additional rounds of screening, for binding to microsomal proteins of a 3H-labeled radioligand of fusicoccin. A novel assay allowing for the direct selection of individual plants exhibiting reduced binding of FC was developed and used as screening procedure. Independent variant lines (43) with stably expressed, reduced binding of FC were isolated and subjected to a detailed characterization of their binding sites. The lines could be subdivided into several distinct classes with respect to these characteristics. In class-I lines, the data indicate a partial conversion of high-affinity binding sites to a low-affinity state. In class-II lines, the affinity of the binding site to FC is strongly reduced while the number of sites, as well as several other biochemical parameters, is completely unchanged, suggesting a specific alteration in the properties of the fusicoccin-binding protein. In class-III lines, the ligand-binding protein complex, while retaining its high affinity, is destabilized at supraoptimal concentrations of FC (such as those used for screening). In wild-type plants, only the high-affinity binding site was detected. Combined, these data prove that the high-affinity sites represent the plant's FC receptor.Abbreviations Ao binding site concentration - FC fusicoccin - FCBP fusicoccin-binding protein - FCol 9-nor-8-hydroxyfusicoccin - KD dissociation constant of the FCBP-radioligand complex We are grateful to Iris Sandorf and Gudrun Henrichs for excellent technical assistance. This work was supported by the Deutsche Forschungsgemeinschaft, Bonn, Germany and by Fonds der Chemischen Industrie (literature provision).  相似文献   
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