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91.
Spatial Distribution of Potential in a Flat Cell: Application to the Catfish Horizontal Cell Layers 总被引:3,自引:0,他引:3
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An analytical solution is obtained for the three-dimensional spatial distribution of potential inside a flat cell, such as the layer of horizontal cells, as a function of its geometry and resistivity characteristics. It was found that, within a very large range of parameter values, the potential is given by [Formula: see text] where r = ρ/ρ0, = z/ρ0, ρ = (Ri/Rm)·ρ0, δ = h/ρ0; K is a constant; J is the assumed synaptic current; ρ, z are cylindrical coordinates; ρ0 is the radius of the synaptic area of excitation; h is the cell thickness; and Ri, Rm are the intracellular and membrane resistivities, respectively. Formula A closely fits data for the spatial decay of potential which were obtained from the catfish internal and external horizontal cells. It predicts a decay which is exponential down to about 40% of the maximum potential but is much slower than exponential below that level, a characteristic also exhibited by the data. Such a feature in the decay mode allows signal integration over the large retinal areas which have been observed experimentally both at the horizontal and ganglion cell stages. The behavior of the potential distribution as a function of the flat cell parameters is investigated, and it is found that for the range of the horizontal cell thicknesses (10-50 μ) the decay rate depends solely on the ratio Rm/Ri. Data obtained from both types of horizontal cells by varying the diameter of the stimulating spot and for three widely different intensity levels were closely fitted by equation A. In the case of the external horizontal cell, the fit for different intensities was obtained by varying the ratio Rm/Ri; in the case of the internal horizontal cell it was found necessary, in order to fit the data for different intensities, to vary the assumed synaptic current J. 相似文献
92.
93.
Kazuharu Ienaga Ko Nakamura Fujio Naka Toshio Goto 《Biochimica et Biophysica Acta (BBA)/General Subjects》1988,967(3)
The metabolic pathway of 1-methylhydantoin (2) via 5-hydroxy-1-methylhydantoin (3), methylparabanic acid (4) and N5-methyloxaluric acid (5) proved to be a major and general one in mammals. Hence the formation of (3), which has not been detected in normal tissue, is likely to be indirect in inflamed tissue, probably depending on the arising formation of (2) from creatinine (1). 相似文献
94.
Human S100A11 exhibits differential steady-state RNA levels in various tissues and a distinct subcellular localization. 总被引:3,自引:0,他引:3
H Inada M Naka T Tanaka G E Davey C W Heizmann 《Biochemical and biophysical research communications》1999,263(1):135-138
In order to analyze the steady-state RNA levels of S100A11 in different tissues, a cDNA fragment of human S100A11 was isolated from a cDNA library. The obtained fragment was labeled and hybridized to RNA isolated from various tissues. The Northern blot analysis revealed that S100A11 RNA levels varied from high in placenta, through intermediate in heart, lung, kidney, and most muscle samples, to barely detectable in brain. An efficient purification method for recombinant S100A11 yielding high quantities was developed. Furthermore, to examine the subcellular localization of this protein, the human polypeptide S100A11 antibodies were raised in rabbit. S100A11 was found to have a localization distinct from other S100 proteins examined, and is mostly localized in the nucleus, with slight variations among different glioblastoma cell types. 相似文献
95.
TFE3 regulates muscle metabolic gene expression, increases glycogen stores, and enhances insulin sensitivity in mice 总被引:1,自引:0,他引:1
96.
Ohashi J Naka I Tokunaga K Inaoka T Ataka Y Nakazawa M Matsumura Y Ohtsuka R 《American journal of physical anthropology》2006,130(4):551-556
Archaeological, linguistic, and genetic studies show that Austronesian (AN)-speaking Polynesian ancestors came from Asia/Taiwan to the Bismarck Archipelago in Near Oceania more than 3,600 years ago, and then expanded into Remote Oceania. However, it remains unclear whether they extensively mixed with indigenous Melanesians who had populated the Bismarck Archipelago before their arrival. To examine the extent of admixture between Polynesian ancestors and indigenous Melanesians, mitochondrial DNA (mtDNA) variations in the D-loop region and the cytochrome oxidase and lysine transfer RNA (COII/tRNA(Lys)) intergenic 9-bp deletion were analyzed in the following three Oceanian populations: 1) Balopa Islanders as AN-speaking Melanesians living in the northwestern end of the Bismarck Archipelago, 2) Tongans as AN-speaking Polynesians, and 3) Gidra as non-Austronesian-speaking Melanesians in the southwestern lowlands of Papua New Guinea. Phylogenetic analysis of mtDNA sequences revealed that more than 60% of mtDNA sequences in the Balopa Islanders were very similar to those in Tongans, suggesting an extensive gene flow from Polynesian ancestors to indigenous Melanesians. Furthermore, analysis of pairwise difference distributions for the D-loop sequences with the 9-bp deletion and the Polynesian motif (i.e., T16217C, A16247G, and C16261T) suggested that the expansion of Polynesian ancestors possessing these variations occurred approximately 7,000 years ago. 相似文献
97.
Fujise T Iwakiri R Wu B Amemori S Kakimoto T Yokoyama F Sakata Y Tsunada S Fujimoto K 《American journal of physiology. Gastrointestinal and liver physiology》2006,291(1):G110-G116
We have previously demonstrated that fasting and ischemia-reperfusion (I/R) induced apoptosis in rat intestinal mucosa. It is widely accepted that apoptosis is induced through two main pathways. This study aimed to compare apoptotic pathways following fasting and I/R. Rats were divided into two groups: the I/R group involved occlusion of the superior mesenteric artery for 60 min, followed by 60-min reperfusion, whereas the fasting group involved fasting for 24 or 48 h. Intestinal apoptosis was assessed as percentage of fragmented DNA, by electrophoresis and by a terminal deoxynucleotidyl transferase mediated dUDP-biotin nick- end labeling (TUNEL) assay. Apoptotic proteins including death ligands/receptors and caspases were evaluated by Western blot analysis. Small intestinal mucosal height and mitochondrial dehydrogenase function were assessed. Fasting and I/R significantly induced intestinal apoptosis. Mucosal height was significantly decreased in fasting rats, and mitochondrial dysfunction was induced only by I/R. Expressions of Fas, Fas ligand, and TNF-alpha type 1 receptor were enhanced in fasting and I/R rats. After I/R, expressions of cytochrome c and cleaved caspase-9 were significantly increased. In contrast, expressions of cleaved caspase-8 and cleaved caspase-3 increased in fasting rats. Fasting promoted mucosal apoptosis via a receptor-mediated type I apoptotic pathway in the rat small intestine, and I/R induced apoptosis via a mitochondria-mediated type II pathway. 相似文献
98.
Arimitsu J Hirano T Higa S Kawai M Naka T Ogata A Shima Y Fujimoto M Yamadori T Hagiwara K Ohgawara T Kuwabara Y Kawase I Tanaka T 《Biochemical and biophysical research communications》2006,342(4):1413-1416
We previously demonstrated a significant association between IL-18 gene polymorphism 105A/C and asthma. In this study, we investigated the relationship of IL-18 gene polymorphism to IL-18 production capability by monocytes. The frequency of gene polymorphisms including IL-18-105A/C and IL-18--137G/C was determined by PCR analyses. The IL-18 production by monocytes stimulated without or with LPS or A23187+PMA for 1day was measured by ELISA. The produced IL-18 spontaneously or in response to A23187+PMA by monocytes was significantly higher for volunteers with 105A/A genotype than with 105A/C genotype. Similarly, the production capability of IL-18 by monocytes from volunteers with -137G/G genotype was significantly higher than that with -137G/C genotype and significant linkage disequilibrium was observed between 105A/C and -137G/C polymorphism. Thus, the genetic capacity to produce more IL-18 in response to stimuli may affect the onset of asthma. 相似文献
99.
Naka H Teruya K Bang JK Aimoto S Tatsumi T Konno H Nosaka K Akaji K 《Bioorganic & medicinal chemistry letters》2006,16(14):3761-3764
Core sequences necessary for substrate recognition and its inhibition at the PR/p3 site of HTLV-1 protease were clarified for the first time. From the cleavage rates of peptides containing a part of the PR/p3 site, a heptapeptide was found to be the minimal sequence required for substrate recognition. The use of synthetic inhibitors containing hydroxyethylamine dipeptide isostere indicated that a tetrapeptide sequence was necessary to achieve potent inhibition. 相似文献
100.
Extracellular adenosine 5′-triphosphate (ATP) activates specific G protein-coupled purinoceptors (P2Y), and ATP-P2Y signaling
pathways induces intracellular Ca2+ mobilization resulting in changes in the gene expression of a variety of proteins in astrocytes. This study investigated
whether the exposure of cultured astrocytes to sublethal ischemia produced resistance to subsequent lethal ischemic stress,
and if so, whether the extracellular ATP-P2Y signaling pathways were responsible for the tolerance. Ischemia-like insults,
sublethal oxygen-glucose deprivation (sOGD), produced tolerance to subsequent lethal OGD stress in cultured astrocytes. Early
during reperfusion after sOGD, the amount of extracellular ATP and the expression of both P2Y1 and P2Y2 receptors were increased, leading to enhanced activation of the extracellular ATP-P2Y signaling pathways. The occurrence
of intracellular spontaneous Ca2+ oscillations was also increased. In addition, sOGD treatment enhanced the expression of the phosphorylated form of extracellular
signal-regulated protein kinases 1 and 2 (p-ERK 1/2), and treatment with an inhibitor of ERK significantly attenuated the sOGD-induced ischemic tolerance of astrocytes. 相似文献