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51.
Proteolytic activity of proteasome on myofibrillar structures 总被引:5,自引:0,他引:5
Richard G. Taylor Caroline Tassy Mariele Briand Nathalie Robert Yves Briand Ahmed Ouali 《Molecular biology reports》1995,21(1):71-73
The physiologic function of proteasome remains unclear. Evidence suggests a role in degradation of ubiquitin-protein conjugates, MHC antigen presentation, and some specificity of substrate within certain cell types. To explore further the properties of proteasome we have examined its effect on a well defined structure, the myofibril. We find that despite its large size (20S) proteasome is able to degrade myofibrils and intact, permeabilized muscle fibrils. The proteins degraded showed some specificity because actin, myosin and desmin were degraded faster than -actinin, troponin T and tropomyosin. Changes in ultrastructure were slow and included a general loss of structure with Z and I bands effected before the M band and costameres. 相似文献
52.
Christophe Tournamille Caroline Le Van Kim Pierre Gane Jean-Pierre Cartron Yves Colin 《Human genetics》1995,95(4):407-410
Spondyloepiphyseal dysplasia tarda (SEDL) is an X-linked recessive disorder characterized in affected males by short stature resulting from a growth defect of the vertebral bodies. We have extended our earlier studies by analyzing 15 families with newly identified microsatellite DNA markers; analysis of recombination events with these markers indicates that the gene responsible for SEDL is located in Xp22 between DXS 16 and DXS 987 on an interval spanning approximately 2 Mb. 相似文献
53.
Mating type allele distribution and phenotypic variability were investigated in field populations of Laccaria bicolor. Sporophores associated with Norway spruce (Picea abies), colonized by natural sources of inoculum and growing in a seed orchard, were sampled to obtain dikaryotic strains and assay their phenotypic variability for traits important to the symbiosis. Basid-iospores were also collected for mating type analysis of different mycelia. Four sporophore mating types were identified containing seven A and five B factors. Out-breeding efficiency was estimated at 73.8% and the population was slightly inbred. Crosses with previously characterized L. bicolor strains from two nearby populations identified in total six sporophore mating types and ten A and nine B factors, for an estimated outbreeding efficiency (85.7%) similar to previous studies of more spatially disparate Laccaria spp. populations. Dikaryotic strains were tested for mycelial growth rate, as a measure of their competitive ability, on agar media containing a soluble (NaH2PO4), or an insoluble (CaHPO4) phosphate source. Their ability to solubilize the latter was also tested to assess their relative capacity to access insoluble, inorganic phosphate. In most cases, significant variation was detected among strains from the same site for all variables. On three sites (VC4, VC5 and VC7), each determined previously to possess a uniform mycelial genotype, phenotypic variability was likely due to epigenetic variation among different strains of the same genotype. Possible evidence for dikaryon-monokaryon crosses was observed in vivo on one sample site (VC2) where adjacent mycelia shared two mating factors. The phenotypic variability of different mycelial genotypes reflected their genetic variability observed as mating type allele diversity and underlined the importance of basidiospore dispersal in introducing new genotypes into the population. The reproductive strategies of L. bicolor are discussed and compared to those of other basidiomycete species. 相似文献
54.
Yves Hurtubise Franois Shareck Dieter Kluepfel Rolf Morosoli 《Molecular microbiology》1995,17(2):367-377
Centre de Recherche en Microbiologie Appliquée, Institut Armand-Frappier, Université du Québec, Ville de Laval, Québec H7N 4Z3, Canada. 相似文献
55.
56.
Dinoflagellate chromosomes observed in thin section show regular patterns which have been shown to correspond to a liquid crystalline helicoidal arrangement of DNA. Peripheral DNA filaments form a system of loops in the surrounding nucleoplasm. When such chromosomes (studied in Prorocentrum micans) are in presence of water, they extend considerably and form a double helical bundle. At the periphery of these bundles, one observes numerous filaments, which are smooth and devoid of nucleosomes; their diameter is constant.This study, in phase contrast and in electron microscopy, allows statistical measurements. A geometrical model is proposed and shows the simplest way to pass from the intact to the extended form. The liquid crystalline character of the chromosome is probably involved in the extension mechanisms. 相似文献
57.
Anne-Marie Bourdeaux Yves Giudicelli Marie-Christine Rebourcet Joseph Nordmann Roger Nordmann 《Biochemical and biophysical research communications》1980,95(1):212-219
At concentrations corresponding to the levels usually reported in the blood of different species in the fed state, gastrin and pancreozymin but not secretin and vasoactive intestinal peptide, stimulate the lipoprotein lipase activity of adipose tissue from fasted rats. The enzyme response to gastrin is, like that to insulin, dependent on the presence of glucose and is not additive with the enzyme response to insulin. On the contrary, the effect of pancreozymin on lipoprotein lipase is glucoseindependent and is additive with the enzyme response to insulin. Both the effects of gastrin and pancreozymin depend on protein synthesis as shown by their suppression by cycloheximide. With isolated fat cells, gastrin increases both the releasable and non-releasable lipase activities whereas pancreozymin increases almost exclusively the non-releasable activity. The mechanisms and the possible physiological significance of these findings are discussed in relationship with the influence of insulin and the nutritional state on adipose tissue lipoprotein lipase. 相似文献
58.
The cellular growth ofChlamydomonas reinhardii is modified by the addition of a total exogenous histone fraction. These modifications may be related to chloroplast DNA replication; they are different according to the different classes of histones. The H1 subfraction seems to be responsible for the effect of the total histone fraction. 相似文献
59.
Yves Crouau 《Zoomorphology》1981,98(2):121-134
Summary The various antennal setae can be differentiated from each other by the number and the type of their dendrites and by the cuticular structure of their external parts; these features correspond to functional differences. Moreover, the work revealed differences in relation to the corresponding setae of a marine Mysidacea previously studied by Guse (1978). Various hypotheses linking the ultrastructural differences to those that characterize the environments in which these two species live can be put forward.Abbreviations A1, A3
simple setae A1, A3
- An
antenna
- B1, B2
setulate setae B1, B2
- Bi
bifid seta
- bp
bending plane
- c1, c2, c3
type 1, 2, or 3 cilia (outer dendritic segments)
- cu
cuticle
- d1, d2, d3
type 1, 2, or 3 dendrites (inner dendritic segments)
- ec
enveloping cell
- g
Golgi apparatus
- h
helically arranged cuticle
- md
microtubule doublet
- n
nucleus
- p
apical pore
- r
ciliary root
- s
setules
- sc
scolopale
- scc
scolopale cell
- Si
sickle-shaped seta
- sm
small seta
- st
stopper
- t
extracellular matter tube 相似文献
60.
Crystalline polysaccharides with 1 → 3−β and 1 → 4−β glycosidic linkages are the most prevalent ones in nature. An interpretation of recent X-ray data on 1 → 3−α glucan shows that it has a ribbon-like crystalline conformation similar to cellulose. Comparison of the crystalline conformation of the four principal homoglucans shows that they fall either in the ‘ribbon-like’ or ‘large amplitude’ helix class. Heteroglucans with a regular sequence of glucosidic linkages show characteristics of the ‘extended conformation’ rather than the ‘coiled conformation’ even when there is 50% of a linkage which in a homoglucan leads to a large amplitude helix. It is concluded that X-ray diffraction analysis fully establishes the hypothesis that the glycosidic linkage type is the determinant of polysaccharide conformation. In this respect, polysaccharides are more like synthetic polymers than proteins or nucleotides; in the latter, it is variation in the substituents which are responsible for the conformational diversity. 相似文献