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Cell adhesion molecules participate in the formation, maturation, function and plasticity of synaptic connections. The growing body of evidence indicates that in the regulation of the synaptic plasticity, in which these molecules play pivotal role, also the proteolytic processes are involved. This review focuses on extracellular proteolysis of the cell adhesion molecules by specific subgroup of the matrix metalloproteinases, a disintegrin and metalloproteases and a disintegrin and metalloproteinase with thrombospondin motifs, jointly referred to as metzincins, in driving coordinated synaptic structural and functional modifications underlying synaptic plasticity in the adult brain. 相似文献
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Differential thermal analysis indicated that the frost resistance of winter rape leaves ( Brassica napus L. var. oleifera L. cv. Gòrczanski), collected from plants grown in the cold (5/2°C), relies mainly on their ability to supercool to −9 to −11°C, i.e. consists in freezing avoidance. Initiation of ice formation in the cold-acclimated leaves resulted in the death of more than 50% of the cells as determined with a conductivity method. The development of freezing tolerance appeared to be an attribute of the second stage of plant hardening and was induced by the exposure of plants to a slightly subzero temperature (−5°C) for 18 h. Such a treatment brought about a sudden and persistent water potential decrease in the leaves, despite the fact that they had reabsorbed water from the medium prior to water potential measurements. Water potential changes were associated with a higher growth capability of the leaves as checked by determinations of disk area increments. It is suggested that the increased frost tolerance of the cold-grown winter rape leaves, subjected to subfreezing temperature, is related to the decreased water potential of the tissue caused by changes in turgor and/or in osmotic pressures of the cells. 相似文献
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Heat-inducible expression of FLP gene in maize cells 总被引:5,自引:1,他引:4
Leszek A. Lyznik Lynne Hirayama K.V. Rao re Abad Thomas K. Hodges 《The Plant journal : for cell and molecular biology》1995,8(2):177-186
The soybean heat-shock gene promoter ( Gmhsp 17.5-E ) has been used to direct expression of gusA and FLP genes in maize cells. At inducible temperatures, in transient expression assays, gusA gene expression controlled by the heat-shock promoter is about 10-fold higher than the expression directed by the CaMV 35S promoter. The Gmhsp 17.5-E promoter preserves its regulatory functions in heterologous maize cells after random integration into genomic DNA.
Heat-shock inducible expression of the FLP gene was investigated by co-transformation of the FLP expression vector (pHsFLP) and a recombination test vector (pUFNeo-FmG) into maize protoplasts. Co-transformed protoplasts were incubated at 42°C for 2 h. This treatment induced recombination of 20–25% of the available FRT sites in transient assays. As a result of heat-shock treatment of stably co-transformed maize cells, activation of gusA gene expression and an associated decrease or elimination of NPT-II activity in transgenic maize lines was observed. Molecular evidence was obtained of the expected DNA excision process catalyzed by the FLP protein in maize transgenic cells. Thus, the experiments presented in this paper indicate that the FLP protein can recognize and subsequently recombine the FRT target sites that had integrated into plant genomic DNA, and that regulated expression of the FLP gene is possible in maize cells using the soybean heat-shock promoter. 相似文献
Heat-shock inducible expression of the FLP gene was investigated by co-transformation of the FLP expression vector (pHsFLP) and a recombination test vector (pUFNeo-FmG) into maize protoplasts. Co-transformed protoplasts were incubated at 42°C for 2 h. This treatment induced recombination of 20–25% of the available FRT sites in transient assays. As a result of heat-shock treatment of stably co-transformed maize cells, activation of gusA gene expression and an associated decrease or elimination of NPT-II activity in transgenic maize lines was observed. Molecular evidence was obtained of the expected DNA excision process catalyzed by the FLP protein in maize transgenic cells. Thus, the experiments presented in this paper indicate that the FLP protein can recognize and subsequently recombine the FRT target sites that had integrated into plant genomic DNA, and that regulated expression of the FLP gene is possible in maize cells using the soybean heat-shock promoter. 相似文献
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Changes in the biological value of sperm depending on the time of the first ejaculation are presented. A control group included 194 boys with normal puberty in whom a biologic value of sperm was evaluated in dependence of the first ejaculation. In all time points a biological value of sperm was significantly worse in the delayed puberty than that in the control group. Twenty four months following the first ejaculation sperm was not normal in any case whereas in the control group normospermia prevailed in this period of time. 相似文献
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Effects of starvation on the maximal activities of some glycolytic and citric acid-cycle enzymes and glutaminase in mucosa of the small intestine of the rat 总被引:2,自引:2,他引:0
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Starvation decreases activities of some glycolytic and citric acid-cycle enzymes, and increases those of glucose 6-phosphatase and fructose bisphosphatase, whereas that of glutaminase is unchanged. These findings may be of significance for the control of glucose metabolism in the absorptive cells of the intestine. 相似文献
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Elbieta Jaboska Leszek Kauc Andrzej Piekarowicz 《Molecular & general genetics : MGG》1975,139(2):157-166
Summary A strain of Haemophilus influenzae, called hpm
- inhibits the growth of phage HP1c1 but not S2. This inhibition is overcome by HP1c1ph mutants. Phage HP1c1 adsorbs normally to hpm
- cells but only a small fraction of infected cells produce phage with a normal burst size or become lysogenic. When hpm
- strains lysogenic for HP1c1 are induced, 100% of the cells yield phage. There is no degradation of phage DNA after infection of hpm
- cells and HP1c1 can normally grow when its DNA is introduced into hpm
- by transfection. The most probable explanation is that in hpm
- cells the penetration of phage DNA is blocked. The hpm
- property behaves as as unstable mutation. 相似文献
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