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排序方式: 共有896条查询结果,搜索用时 15 毫秒
41.
Huerta JM González S Fernández S Patterson AM Lasheras C 《Free radical research》2004,38(11):1215-1221
Oxidative stress has been suggested as one of the physiopathologic conditions underlying the association of total plasma homocysteine (p-tHcy) with cardiovascular disease (CVD), but this hypothesis has not been validated in human epidemiological studies. We measured plasma and erythrocyte antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), along with serum lipid-soluble antioxidants alpha-tocopherol, beta-carotene, lycopene and retinol, in a sample of 123 healthy elderly subjects (54 men, 69 women). Plasma malondialdehyde (p-MDA) was determined as a marker of lipid peroxidation, and p-tHcy was quantified by HPLC. No significant differences were found for p-MDA, GPx or SOD activities or serum antioxidant concentrations, in subjects with elevated p-tHcy (≥15 μmol/l) as compared to those with lower plasma homocysteine. Hyperhomocysteinemia did not lead to increased risk of having the highest p-MDA values, in either sex. We found no evidence that p-tHcy was associated with lipid peroxidation in this elderly human sample. Our results do not support the view that hyperhomocysteinemia would induce an adaptive response of antioxidant systems, either. More epidemiologic and clinical research is needed to clarify whether homocysteine promotes atherosclerosis by means of an oxidative stress mechanism. 相似文献
42.
Modamio-Høybjør S Moreno-Pelayo MA Mencía A del Castillo I Chardenoux S Armenta D Lathrop M Petit C Moreno F 《Human genetics》2003,112(1):24-28
Hereditary non-syndromic sensorineural hearing loss (NSSHL) is a genetically highly heterogeneous group of disorders. Autosomal dominant forms account for up to 20% of cases. To date, 39 loci have been identified by linkage analysis of affected families that segregate NSSHL forms in the autosomal dominant mode (DFNA). Investigation of a large Spanish pedigree with autosomal dominant inheritance of bilateral and progressive NSSHL of postlingual onset excluded linkage to known DFNA loci and, in a subsequent genome-wide scan, the disorder locus was mapped to 3q28-29. A maximum two-point LOD score of 4.36 at theta=0 was obtained for marker D3S1601. Haplotype analysis placed the novel locus, DFNA44, within a 3-cM genetic interval defined by markers D3S1314 and D3S2418. Heteroduplex analysis and DNA sequencing of coding regions and exon/intron boundaries of two genes (CLDN16 and FGF12) in this interval did not reveal disease-causing mutations. 相似文献
43.
Nitric oxide triggers the toxicity due to glutathione depletion in midbrain cultures through 12-lipoxygenase 总被引:5,自引:0,他引:5
Canals S Casarejos MJ de Bernardo S Rodríguez-Martín E Mena MA 《The Journal of biological chemistry》2003,278(24):21542-21549
Glutathione (GSH) depletion is the earliest biochemical alteration shown to date in brains of Parkinson's disease patients. However, data from animal models show that GSH depletion by itself is not sufficient to induce nigral degeneration. We have previously shown that non-toxic inhibition of GSH synthesis with l-buthionine-(S,R)-sulfoximine in primary midbrain cultures transforms a nitric oxide (NO) neurotrophic effect, selective for dopamine neurons, into a toxic effect with participation of guanylate cyclase (GC) and cGMP-dependent protein kinase (PKG) (Canals, S., Casarejos, M. J., de Bernardo, S., Rodríguez-Martín, E., and Mena, M. A. (2001) J. Neurochem. 79, 1183-1195). Here we demonstrate that arachidonic acid (AA) metabolism through the 12-lipoxygenase (12-LOX) pathway is also central for this GSH-NO interaction. LOX inhibitors (nordihydroguaiaretic acid and baicalein), but not cyclooxygenase (indomethacin) or epoxygenase (clotrimazole) ones, prevent cell death in the culture, even when added 10 h after NO treatment. Furthermore, the addition of AA to GSH-depleted cultures precipitates a cell death process that is indistinguishable from that initiated by NO in its morphology, time course, and 12-LOX, GC, and PKG dependence. The first AA metabolite through the 12-LOX enzyme, 12-hydroperoxyeicosatetraenoic acid, induces cell death in the culture, and its toxicity is greatly enhanced by GSH depletion. In addition we show that if GSH synthesis inhibition persists for up to 4 days without any additional treatment, it will induce a cell death process that also depends on 12-LOX, GC, and PKG activation. In this study, therefore, we show that the signaling pathway AA/12-LOX/12-HPETE/GC/PKG may be important in several pathologies in which GSH decrease has been documented, such as Parkinson's disease. The potentiating effect of NO over such a signaling pathway may be of relevance as part of the cascade of events leading to and sustaining nerve cell death. 相似文献
44.
de la Fuente MT Casanova B Cantero E Hernández del Cerro M Garcia-Marco J Silva A Garcia-Pardo A 《Biochemical and biophysical research communications》2003,311(3):708-712
We recently showed that alpha4beta1 integrin induces B-cell chronic lymphocytic leukemia (B-CLL) cell resistance to fludarabine-induced apoptosis via upregulation of Bcl-xL. We have now studied whether p53 was involved in this response. Cells from five B-CLL patients with wild-type p53 determined by DNA sequencing, or from the EHEB cell line, cultured on the alpha4beta1 ligand H/89 during fludarabine treatment, showed significantly higher viability (P相似文献
45.
46.
Role of 17beta-estradiol administration on insulin sensitivity in the rat: implications for the insulin receptor 总被引:6,自引:0,他引:6
González C Alonso A Grueso NA Díaz F Esteban MM Fernández S Patterson AM 《Steroids》2002,67(13-14):993-1005
The role of 17beta-estradiol in the early steps of insulin action is only partially known, although its effect on glucose homeostasis has been reported. In this paper, we attempt to prove the influence of 17beta-estradiol on the insulin receptor of ovariectomized rats treated with different hormonal doses. Our results show that high doses of estradiol impair insulin sensitivity while low doses improve it. We think that these results are the consequence of changes at a molecular level, because high doses of estradiol produced lower expression of the insulin receptor gene, lower content of this receptor in target tissues, and lower phosphorylation of insulin receptor in these tissues. However, low doses of estradiol seem to produce just the opposite. The possible existence of consensus response elements in the insulin receptor gene promoter to estradiol could be controlling the expression of this gene, this control being dose and timing dependent. Moreover, we cannot discard a possible effect of estradiol on the activity of protein tyrosine phosphatases, and therefore, on the activity of the insulin receptor. These new findings improve knowledge about the possible risk for insulin resistance in women taking oral contraceptives or receiving hormonal replacement therapy around the menopause, but could also open the door towards the possible utilization of 17beta-estradiol in some diabetes cases. 相似文献
47.
Cutting edge: dynamic redistribution of tetraspanin CD81 at the central zone of the immune synapse in both T lymphocytes and APC 总被引:6,自引:0,他引:6
Mittelbrunn M Yáñez-Mó M Sancho D Ursa A Sánchez-Madrid F 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(12):6691-6695
The tetraspanin CD81 has been involved in T-dependent B cell-mediated immune responses. However, the behavior of CD81 during immune synapse (IS) formation has not been elucidated. We determined herein that CD81 redistributed to the contact area of T cell-B cell and T cell-dendritic cell conjugates in an Ag-dependent manner. Confocal microscopy showed that CD81 colocalized with CD3 at the central supramolecular activation complex. Videomicroscopy studies with APC or T cells transiently expressing CD81-green fluorescent protein (GFP) revealed that in both cells CD81 redistributed toward the central supramolecular activation complex. In T lymphocytes, CD81-GFP rapidly redistributed to the IS, whereas, in the APC, CD81-GFP formed a large accumulation in the contact area that later concentrated in a discrete cluster and waves of CD81 accumulated at the IS periphery. These results suggest a relevant role for CD81 in the topography of the IS that would explain its functional implication in T cell-B cell collaboration. 相似文献
48.
The tautomerase active site of macrophage migration inhibitory factor is a potential target for discovery of novel anti-inflammatory agents 总被引:8,自引:0,他引:8
Lubetsky JB Dios A Han J Aljabari B Ruzsicska B Mitchell R Lolis E Al-Abed Y 《The Journal of biological chemistry》2002,277(28):24976-24982
Macrophage migration inhibitory factor (MIF) is an immunoregulatory protein that is a potential therapeutic target for a number of inflammatory diseases. Evidence exists that an unexpected catalytic active site of MIF may have a biological function. To gain further insight into the role of the catalytic active site, a series of mutational, structural, and biological activity studies were performed. The insertion of an alanine between Pro-1 and Met-2 (PAM) abolishes a non-physiological catalytic activity, and this mutant is defective in the in vitro glucocorticoid counter-regulatory activity of MIF. The crystal structure of MIF complexed to (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1), an inhibitor of MIF d-dopachrome tautomerase activity, reveals that ISO-1 binds to the same position of the active site as p-hydroxyphenylpyruvic acid, a substrate of MIF. ISO-1 inhibits several MIF biological activities, further establishing a role for the catalytic active site of MIF. 相似文献
49.
50.
The role of astroglia on the survival of dopamine neurons 总被引:5,自引:0,他引:5
Mena MA de Bernardo S Casarejos MJ Canals S Rodríguez-Martín E 《Molecular neurobiology》2002,25(3):245-263
Glial cells play a key role in the function of dopamine (DA) neurons and regulate their differentiation, morphology, physiological
and pharmacological properties, survival, and resistance to different models of DA lesion. Several studies suggest that glial
cells may be important in the pathogenesis of Parkinson’s disease (PD), a common neurodegenerative disorder characterized
by degeneration of the nigrostriatal DA system. In this disease the role of glia could be due to the excessive production
of toxic products such as nitric oxide (NO) or cytokines characteristic of inflammatory process, or related to a defective
release of neuroprotective agents, such as small antioxidants with free radical scavenging properties or peptidic neurotrophic
factors. 相似文献