全文获取类型
收费全文 | 4446篇 |
免费 | 302篇 |
国内免费 | 2篇 |
出版年
2023年 | 36篇 |
2022年 | 48篇 |
2021年 | 116篇 |
2020年 | 66篇 |
2019年 | 80篇 |
2018年 | 112篇 |
2017年 | 96篇 |
2016年 | 167篇 |
2015年 | 216篇 |
2014年 | 268篇 |
2013年 | 268篇 |
2012年 | 383篇 |
2011年 | 318篇 |
2010年 | 258篇 |
2009年 | 229篇 |
2008年 | 235篇 |
2007年 | 248篇 |
2006年 | 227篇 |
2005年 | 200篇 |
2004年 | 195篇 |
2003年 | 177篇 |
2002年 | 133篇 |
2001年 | 69篇 |
2000年 | 58篇 |
1999年 | 47篇 |
1998年 | 42篇 |
1997年 | 38篇 |
1996年 | 24篇 |
1995年 | 32篇 |
1994年 | 21篇 |
1993年 | 20篇 |
1992年 | 25篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1980年 | 11篇 |
1976年 | 11篇 |
1975年 | 9篇 |
1974年 | 9篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1968年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有4750条查询结果,搜索用时 31 毫秒
11.
M Zeviani M Nakagawa J Herbert M I Lomax L I Grossman A A Sherbany A F Miranda S DiMauro E A Schon 《Gene》1987,55(2-3):205-217
12.
Summary Two different aspects of tritiated thymidine (3H-Tdr) reutilisation in skeletal muscle were examined. Injection of a high dose (7 Ci/g) of 3H-Tdr into mice prior to crush injury of skeletal muscle resulted in heavy labelling (grain counts) of myotube nuclei 9 d later. In contrast, myotube nuclei were essentially unlabelled when a low dose (1 Ci/g) of 3H-Tdr was injected at similar times with respect to injury. It was concluded that labelling seen after the high dose was due to reutilisation of 3H-Tdr. (Such 3H-Tdr reutilisation can account for the results of Sloper et al. (1970) which previously supported the concept of a circulating muscle precursor cell.) When replicating muscle precursors were labelled directly with 3H-Tdr 48 h after injury, the percentages of labelled myotube nuclei and the distribution of nuclear grain counts were similar with either high or low dose.We also investigated whether the light labelling seen in regenerated myotube nuclei after 9 d, when 3H-Tdr had been injected before the onset of myogenesis (as found by McGeachie and Grounds 1987), was due to 3H-Tdr reutilisation or, alternatively, to proliferation of local cells in the wound which subsequently gave rise to muscle precursors. Labelling of myotube nuclei was compared in mice injected with 3H-Tdr either 2 h before, or 2 h after injury. In another experiment, mice were injected 12 h after injury and lesions sampled 1, 12 or 36 h later, to see whether local cells were replicating 12 h after injury, and what labelled cells subsequently entered to wound. No difference was found in myotube labelling between mice injected before or after injury, and no cells replicating locally in the wound at 12 h after injury were observed. The results clearly show that the light labelling was due to 3H-Tdr reutilisation. 相似文献
13.
Autoradiographic studies were carried out on regenerating muscles of adult chickens. Three different muscles of hens were injured, and tritiated thymidine (1 μCi/g) was injected at various times after injury to label replicating muscle precursors. Detailed comparisons of grain counts over premitotic nuclei in samples removed one hour after injection of tritiated thymidine, and of postmitotic myotube nuclei in samples removed 10 days after injury (when labeled precursors had fused to form myotubes), revealed how many times some labeled precursors had divided before fusing into myotubes. DNA synthesis in muscle precursors was initiated 30 h after injury. Grain counts of myotube nuclei indicated that many muscle precursors labeled at the onset of myogenic cell proliferation had divided only once, or twice, before fusing into myotubes. The relationship of these in vivo results to the cell lineage model of myogenesis is discussed. 相似文献
14.
Acid and alkaline phosphatase activities in culture liquid and mycelial extract during autolysis were studied in seven fungi of the general Ascomycotina, Basidiomycotina and Zygomycotina. High activities of extracellular and mycelial extract acid phosphatase and lower activities of alkaline phosphatase were found in Ascomycotina, and acid phosphatase was present in Basidiomycotina. In Zygomycotina only mycelial extract alkaline phosphatase activity was detected. A correlation between degree of autolysis, pH and acid phosphatase activity was demonstrated. 相似文献
15.
E Bonilla C E Samitt A F Miranda A P Hays G Salviati S DiMauro L M Kunkel E P Hoffman L P Rowland 《Cell》1988,54(4):447-452
Dystrophin is the altered gene product in Duchenne muscular dystrophy (DMD). We used polyclonal antibodies against dystrophin to immunohistochemically localize the protein in human muscle. In normal individuals and in patients with myopathies other than DMD, dystrophin was localized to the sarcolemma of the fibers. The protein was absent or markedly deficient in DMD. The sarcolemmal localization of dystrophin is consistent with other evidence that there are structural and functional abnormalities of muscle surface membranes in DMD. 相似文献
16.
Intercellular junctions in the seminiferous epithelium of the testis of Triatoma infestans were examined by conventional electron microscopy, tannic acid fixation, electron-opaque tracers, and freeze-fracture techniques. Distinctive aspects of the intercellular junctions are described in different regions of the testis follicles. In the basal region, close to the basal lamina, smooth septate junctions intermingled with gap junctions were observed between sustentacular cells. In the parabasal regions of the seminiferous epithelium, plated septate junctions, 'molluscous and arthropod' type (according to the classification of Green, 1981), were observed. Over the above junctions, in the central regions, also located between sustentacular cell membranes, parallel rows of intramembrane particles form successive belts of widely spaced septate junctions in an atypical configuration. Invertebrate gap junctions were also observed between adjacent spermatocyte membranes. 相似文献
17.
Cloning and expression of human nebulin cDNAs and assignment of the gene to chromosome 2q31-q32 总被引:2,自引:0,他引:2
M Zeviani B T Darras R Rizzuto G Salviati R Betto E Bonilla A F Miranda J Du C Samitt G Dickson 《Genomics》1988,2(3):249-256
We have isolated two nonoverlapping cDNAs encoding human nebulin, a muscle-specific protein. Northern hybridization analysis shows that nebulin is encoded by a huge message at least 25 kb in length. By hybridizing two nonoverlapping cDNAs to DNA isolated from rodent X human cell hybrids, we assign this presumably single-copy gene to human chromosome 2; sublocalization studies indicate that the nebulin gene is on the long arm of the chromosome, in the region 2q31-q32. 相似文献
18.
B Pham Huu ChanhLasserre A Pham Huu Chanh A L Palhares de Miranda P Tronche J Couquelet C Rubat 《Prostaglandins, leukotrienes, and essential fatty acids》1988,33(2):143-147
The effects of 2-(2 dimethylaminoethyl) 5-benzylidene 6-methyl (2H,4H)-3-pyridazinone (III) were studied on the biosynthesis of TXA2 and PGI2 in vitro the TXA2 and PGI2 synthetase activity of heart tissue. Biosyntheses of TXA2 and PGI2 were carried out using arachidonic acid as a substrate and horse platelet and aorta microsomes as sources of TXA2 and PGI2 synthetases respectively. TXB2 and 6-keto PGF1 alpha were determined by RIA. III--did not significantly modify either the biosynthesis of PGI2 in vitro or the PGI2 synthetase activity of heart tissue. did not significantly inhibit TXA2 biosynthesis in vitro but markedly reduced the TXA2 synthetase activity of heart tissue: for a microsomal fraction concentration of 100 micrograms protein, the ID50 was 6.37 X 10(-5) M +/- 1.29 X 10(-8) M. Thus III behaves as a specific inhibitor of the TXA2 synthetase activity of heart tissue and could have a beneficial use in therapeutics. 相似文献
19.
Christopher A. Mitchell John K. McGeachie Miranda D. Grounds 《Cell and tissue research》1992,269(1):159-166
Summary Skeletal muscle regeneration in SJL/J and BALB/c mice subjected to identical crush injuries is markedly different: in SJL/J mice myotubes almost completely replace damaged myofibres, whereas BALB/c mice develop fibrotic scar tissue and few myotubes. To determine the cellular changes which contribute to these differential responses to injury, samples of crushed tibialis anterior muscles taken from SJL/J and BALB/c mice between 1 and 10 days after injury were analysed by light and electron microscopy, and by autoradiography. Longitudinal muscle sections revealed about a 2-fold greater total mononuclear cell density in SJL/J than BALB/c mice at 2 to 3 days after injury. Electron micrographs identified a similar proportion of cell types at 3 days after injury. Autoradiographic studies showed that the proportions of replicating mononuclear cells in both strains were similar: therefore greater absolute numbers of cells (including muscle precursors and macrophages) were proliferating in SJL/J muscle. Removal of necrotic muscle debris in SJL/J mice was rapid and extensive, and by 6 to 8 days multinucleated myotubes occupied a large part of the lesion. By contrast, phagocytosis was less effective in BALB/c mice, myotube formation was minimal, and fibrotic tissue conspicuous. These data indicate that the increased mononuclear cell density, more efficient removal of necrotic muscle, together with a greater capacity for myotube formation in SJL/J mice, contribute to the more successful muscle regeneration seen after injury. 相似文献
20.
Physiological and biochemical studies on Fusarium oxysporum f. sp. lycopersici race 2 for its biocontrol by nonpathogenic fungi 总被引:1,自引:0,他引:1
Abstract The self-degradation of the phytopathogenic fungus Fusarium oxysporum f. sp. lycopersici race 2 ( F. oxysporum l. 2), which reached an autolysis degree of 72% after 60 days of incubation in stationary culture, occurred principally during the first 14 days of incubation, when considerable β-(1,3)-glucanase, pectinase, xylanase and chitinase activities were detected in the culture fluids. The levels of β-(1,3)-glucanase, pectinase, cellulase, chitinase and xylanase activities increased in the culture fluids of this fungus, when the culture medium was supplemented with different inducers. The vegetable juice (V8) that contained tomato juice, was the best inducer for most of these activities. Chitosan, glucosamine oligomers and Mucor rouxii mycelium extract were found to have an inhibitory effect on F. oxysporum l. 2 growth. When incubating cell walls from young mycelia of F. oxysporum l. 2 with enzymic precipitates obtained from autolyzed cultures of Mucor rouxii, Aspergillus nidulans, Penicillin oxalicum and Penicillium purpurogenum , degradations of 45%, 22%, 21% and 12%, respectively, were detected. 相似文献