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61.
Z. Shen J. Liu D. C. Marcus N. Shiga P. Wangemann 《The Journal of membrane biology》1995,146(3):283-291
Vestibular dark cell epithelium secretes K+ via I
sKchannels in the apical membrane. The previous observation that disulfonic stilbenes increased the equivalent short circuit current (I
sc) suggested that these agents might be useful investigative tools in this tissue. The present experiments were conducted to determine if the increase in I
scwas associated with an increase in K+ flux and if the effect was directly on the I
sKchannel or indirectly via a cytosolic intermediary. Measurements of transepithelial K+ flux with the K+-selective vibrating probe and of changes in net cellular solute flux by measurements of epithelial cell height showed that 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) increased K+ flux by a factor of 1.96±0.71 and caused net solute efflux. The apical membrane was partitioned with a macropatch pipette and DIDS was applied either to the membrane outside the pipette, inside the pipette or to the entire apical membrane. DIDS inside the pipette increased the current across the patch, the membrane conductance, the slowly-inactivating (I
sK) component of the membrane current and shifted the reversal voltage toward the equilibrium potential for K+. DIDS outside the patch decreased the patch current and conductance, consistent with shunting of current away from the membrane patch. These findings strongly support the notion that DIDS increases K+ secretion through I
sKchannels in the apical membrane of vestibular dark cell epithelium by acting directly on the channels or on a tightly colocalized membrane component.We thank Dr. Peter J.S. Smith and Alan Shipley of the National Vibrating Probe Facility at the Marine Biological Laboratory at Woods Hole, MA for their support and assistance in the measurements of K+ flux. This work was supported by National Institutes of Health grants R01-DC00212, R29-DC1098 and P41-RR01395. 相似文献
62.
Nagira K Hayashida M Shiga M Sasamoto K Kina K Osada K Sugahara T Murakami H 《Cytotechnology》1995,17(2):117-125
Human-human hybridoma cells secreting a human monoclonal antibody were cultured in a serum-free medium containing various organic pH buffers in order to clarify their effects on cell growth and antibody production. Organic pH buffers having either one sulfonic acid and several acyclic amine moieties, or several cyclic amine moieties containing two amino nitrogen did not inhibit cell growth; while other organic buffers sulfonic acid moiety plus several cyclic amine moieties containing one amino nitrogen slightly decreased cell growth, but enhanced antibody production. Using Fujita's organic conceptual diagram, a relationship between the organicity and inorganicity of a pH buffer to cell growth and antibody production was found. pH buffers with large inorganicity and small organicity values were favorable for cell growth, and buffers with small inorganicity and large organicity values were preferred to enhance antibody production. Although the pH buffering range affects cell growth, its effect on antibody production is not clear. In conclusion, 2-morpholinoethanesulfonic acid (MES), 3-morpholino-propanesulfonic acid (MOPS) and 1, 2-N, N-bis[N, N-di(2-sulfonoethyl)piperazinyl]ethane (Bis-PIPES) are shown to be the most optimal of the buffers tested, because they enhanced antibody production without decreasing the cell growth among the pH buffers tested here. 相似文献
63.
The intermediate free radicals generated from phenols, naphthols and benzoate, in the peroxidase- and oxidase-reactions of horse radish peroxidase and in the peroxidase-reaction of methemoglobin, were studied by electron spin resonance spectroscopy.The difference between the peroxidase- and oxidase-reactions of HRP are demonstrated, i.e., the ferro horse radish peroxidase-O2 system attacks both phenols and benzoate yielding unidentified radicals, which may be hydroxy-cyclohexadienyl radicals, while the horse radish peroxidase-H2O2 system reacts only with phenols and naphthols producing the phenoxy-and naphthoxy-radicals.Phenoxy-radical formation from phenols, in the reactions horse radish peroxidase-H2O2 and methemoglobin-H2O2, occurs independently of the molecular sizes of phenols but dependently on their redox-potentials.On the basis of kinetic studies on methemoglobin-H2O2 system, the existence of a reactive intermediate complex between methemoglobin and H2O2 is proposed, which may be similar to compound-I or -II of horse radish peroxidase and which further degenerates to MetHb radical. The oxidation of phenols and naphthols takes place outside of the hemepocket of methemoglobin. 相似文献
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68.
Chromosomal translocation and inverted duplication associated with integrated hepatitis B virus in hepatocellular carcinomas. 总被引:11,自引:5,他引:6
T Tokino S Fukushige T Nakamura T Nagaya T Murotsu K Shiga N Aoki K Matsubara 《Journal of virology》1987,61(12):3848-3854
Integrated hepatitis B virus (HBV) DNA is found in hepatocellular carcinomas which develop in HBV carriers. Presented here are the results of analyses of four integrants that show chromosomal rearrangements associated with the integrated HBV DNA. Two clones (p4 and C15) were found to have large inverted repeating structures, each consisting of HBV genome along with flanking cellular sequences. The structure must have arisen by duplication of the primary integrant, including the flanking cellular DNA, followed by recombination within the viral DNA. One of the two viral arms in each clone joins to the other viral arm at the "cohesive end region." Two clones (DA2-2 and DA2-6) were found to have integrated HBV sequences, each flanked by cellular DNAs from different chromosomes (chromosome X joined to 17 and chromosome 5 joined to 9). They must be the products of cellular DNA translocations using the integrated HBV DNA as the switch point. The viral DNA in each clone is a continuous stretch of a single virus genome with one end in the cohesive end region. These complex structures seem to have been produced by activation of the cohesive end of an integrant viral genome, followed by its recombination with another chromosomal DNA. 相似文献
69.
Hideyuki Hiraishi Akira Terano Shin-ichi Ota Junji Shiga Takemaru Kobayashi Hiromi Harada Masao Ishii Kevin J. Ivey Tsuneaki Sugimoto 《Prostaglandins & other lipid mediators》1986,32(2)
The effect of cAMP on prostaglandin production may depend on cell types. To clarify the relationship between PG and cAMP, we examined arachidonate's effects on PG synthesis and intracellular cAMP accumulation in monolayers of rat gastric mucosal cells. These cells produced PGE2, PGI2 and thromboxaneA2 (TXA2) in amounts of 316±18, 100±7 and 30±5 pg per 105 cells in 10 min, respectively, in response to 10μM arachidonic acid (AA). The production of these PG, however, leveled off subsequently. Cells initially exposed to AA responded poorly to a subsequent stimulation by AA. AA simultaneously stimulated intracellular cAMP accumulation; this stimulatory effect on cAMP production was abolished by the pretreatment with indomethacin. Nevertheless, the pretreatments with dibutyryl cAMP (0.1–5mM) did not alter the amount of subsequent AA-induced PGE2 production. Furthermore, the preincubation with 1mM isobutyl methyl xanthine also failed to affect PGE2 synthesis, while it increased intracellular cAMP accumulation. Our studies suggest (1) AA stimulates intracellular cAMP formation in cultured gastric mucosal cells, linked with conversion of AA to cyclooxygenase metabolites, (2) AA-induced PG production is limited in these cells, and (3) it seems, however, unlikely that intracellular cAMP modulates AA metabolism to PG. 相似文献
70.
Genetic determinant of pyocin R2 in Pseudomonas aeruginosa PAO. I. Localization of the pyocin R2 gene cluster between the trpCD and trpE genes 总被引:9,自引:0,他引:9
Thirty-seven mutants defective in pyocin R2 production in the P. aeruginosa PAO strain were subjected to fine mapping of pyocin R2 genes by transduction with phage F116L. Sixteen complementation groups (designated prtA through prtP) involved in pyocin R2 production were tentatively identified by complementation tests using phage F116L. Their linkages to trpC and trpE markers and fine mapping by three point crosses demonstrated that most of the mutations (prtA through prtN) were located in between trpC and trpE, and that the prtP mutation was localized outside this major prt cluster but in the proximity of the rifA and strA region. 相似文献