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221.
Uncoupling proteins (UCPs) belong to the mitochondrial anion carrier protein family and mediate regulated proton leak across the inner mitochondrial membrane. Free fatty acids, aldehydes such as hydroxynonenal, and retinoids activate UCPs. However, there are some controversies about the effective action of retinoids and aldehydes alone; thus, only free fatty acids are commonly accepted positive effectors of UCPs. Purine nucleotides such as GTP inhibit UCP-mediated mitochondrial proton leak. In turn, membranous coenzyme Q may play a role as a redox state-dependent metabolic sensor that modulates the complete activation/inhibition of UCPs. Such regulation has been observed for UCPs in microorganisms, plant and animal UCP1 homologues, and UCP1 in mammalian brown adipose tissue. The origin of UCPs is still under debate, but UCP homologues have been identified in all systematic groups of eukaryotes. Despite the differing levels of amino acid/DNA sequence similarities, functional studies in unicellular and multicellular organisms, from amoebae to mammals, suggest that the mechanistic regulation of UCP activity is evolutionarily well conserved. This review focuses on the regulatory feedback loops of UCPs involving free fatty acids, aldehydes, retinoids, purine nucleotides, and coenzyme Q (particularly its reduction level), which may derive from the early stages of evolution as UCP first emerged. 相似文献
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Ryuji Murakami Kiyoshi Yamada Shinya Nagafuchi Satoshi Hachimura Takeshi Takahashi Shuichi Kaminogawa Mamoru Totsuka 《Cytotechnology》2002,40(1-3):59-65
Our previous studies showed that dietary nucleotides fed to mice enhanced the secretion of interleukin 7 (IL-7) and transforming
growth factor β (TGF-β) from intestinal epithelial cells (IECs). To explore whether nucleotides influence IECs directly to
enhance the secretion of the cytokines or not, the effects of nucleotides added in vitro on the cytokine secretion from primary-cultured murine IECs were examined. When the mixture of nucleotide 5′-monophosphates
(CMP, GMP, IMP, and UMP) or individual nucleotide 5′-monophosphates were added to the primary culture of IECs derived from
BALB/c mice, the secretion of IL-7, but not that of TGF-β, was increased significantly. Addition of nucleotides to the culture
did not alter the number of the IECs. Secretion of IL-6 and granulocyte-macrophage colony-stimulating factor, which are known
to be secreted from IECs, was not enhanced by the addition of nucleotides. These results demonstrate that nucleotides can
affect IECs directly to enhance the secretion of IL-7, and suggest that the increased secretion of TGF-β from IECs by dietary
nucleotides was due to indirect effects of the nucleotides, which may affect intestinal microflora or cells other than IECs
that in turn influence the cytokine secretion of IECs.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
225.
反义核酸抗肝炎病毒研究进展 总被引:2,自引:0,他引:2
病毒性肝炎的治疗一直是困扰人类的一个难题.目前可利用的药物仍屈指可数.反义核酸技术的发展为病毒性肝炎的治疗带来了新的希望.利用反义DNA,反义RNA和核酶技术来抑制乙型肝炎病毒,丙型肝炎病毒和丁型肝炎病毒,在体外已进行了大量的研究,体内也进行了一些研究,为临床应用反义核酸治疗病毒性肝炎奠定了基础. 相似文献
226.
用寡聚核苷酸片段筛选白色念珠菌MAPK的基因家族 总被引:9,自引:6,他引:3
促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)是一类与哺乳动物p34^CDC2同源性很高的Ser/Thr蛋白激酶,在多个不同的信号转导途径中起作用。现有的实验语气表明,MAPK很可能在白色念珠菌形态发生中起作用。我们根据白色念念菌的已知的两个MAPK基因;CEK1与MKC1第Ⅶ亚结构域的核苷酸序列合成卫段27nt的寡核苷酸,作为探针来筛选白色念穆 相似文献
227.
Abstract: GTP and GDP decreased the saturable binding of [3 H]baclofen or [3 H]γ-aminobutyric acid ([3 H]GABA) to GABAB but not GABAA receptors whereas GMP displayed negligible activity. This effect was specific to guanyl nucleotides and was not mimicked by high concentrations of ATP. The inhibition of ligand binding was the result of a diminished receptor affinity with no change in receptor number. The use of a complete physiological saline solution rather than Tris buffer plus Ca2+ or Mg2+ increased the potency of GTP at the GABAB receptor. The results are discussed in relation to the effects of GABA and GTP on adenylate cyclase activity in the brain. 相似文献
228.
Both NaCl and NaF promoted PGE2 binding to epididymal adipocyte membranes by apparent increase in the binding affinity. In order to distinguish between the effect of fluoride and the ‘salt effect’ of sodium on PGE2 binding, the effects of Mg2+ and guanyl nucleotides on PGE2 binding in the presence of NaCl or NaF were compared. Mg2+ decreased PGE2 binding; high NaF concentration abolished this inhibition, while increased NaCl concentratipns did not affect the Mg2+ inhibition. In the presence of Mg2+ the effects of NaCl and NaF were additive. The enhancement of PGE2 binding by fluoride, unlike sodium, was dependent on the presence of Mg2+. Induction of the membranes with GDPβS, Gpp(NH)p, GTP or GTPγS increased PGE, binding. Gradual increase in NaF concentrations in the presence of guanyl nucleotides resulted in stimulation of PGE2 binding at low NaF concentrations and inhibition of PGE2 binding at higjh NaF concentrations. No changes in the stimulatory action of NaCl on PGE2 binding were observed in the simulatenous presence of NaCl and guanyl nucleotides. A biphasic effect on PGE2 binding was observed with a wide concentration range of guanyl nucleotides. Treatment of the isolated membranes with cholera or pertussis toxins stimulated the adenylyl cyclase activity of the membranes, but failed to influence PGE2 binding. The implications of these findings are discussed. 相似文献
229.
Takeshi Hanami Rieko Oyama Masayoshi Itoh Ayako Yasunishi-Koyama Yoshihide Hayashizaki 《Nucleosides, nucleotides & nucleic acids》2013,32(8):608-615
The incorporation of deoxynucleoside triphosphates (dNTPs) catalyzed by polymerases is conventionally examined using gel electrophoresis autoradiography. Here, we studied an alternative method, pyrosequencing, to verify the incorporation of dNTPs containing unnatural nucleotides by polymerases. We found that the pyrosequencing method more rapidly and easily confirmed the incorporation of dNTPs than the conventional method, especially in the presence of low-efficiency dNTP polymerases. Furthermore, the method can detect the pyrophosphorolysis reaction just before the position of the unnatural nucleic acid, and the efficiency of incorporation just after it. 相似文献
230.
Christelle Thibault Jacky Falcón Shelley S. Greenhouse Christopher A. Lowery † William A. Gern Jean-Pierre Collin 《Journal of neurochemistry》1993,61(1):332-339
Abstract: The light/dark cycle influences the rhythmic production of melatonin by the trout pineal organ through a modulation of the serotonin N -acetyltransferase (NAT) activity. In static organ culture, cyclic AMP (cAMP) levels (in darkness) and NAT activity (in darkness or light) were stimulated in the presence of forskolin, isobutylmethylxanthine, or theophylline. Analogues of cAMP, but not of cyclic GMP, induced an increase in NAT activity. Light, applied after dark adaptation, inhibited NAT activity. This inhibitory effect was partially prevented in the presence of drugs stimulating cAMP accumulation. In addition, cAMP accumulation and NAT activity increase, induced by forskolin, were temperature dependent. Finally, melatonin release, determined in superfused organs under normal conditions of illumination, was stimulated during the light period of a light/dark cycle by adding an analogue of cAMP or a phosphodiesterase inhibitor. However, no further increase in melatonin release was observed during the dark phase of this cycle in the presence of the drugs. This report shows for the first time that cAMP is a candidate as intracellular second messenger participating in the control of NAT activity and melatonin production by light and temperature. 相似文献