首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   105篇
  免费   6篇
  111篇
  2023年   1篇
  2020年   1篇
  2019年   1篇
  2015年   6篇
  2014年   5篇
  2013年   3篇
  2012年   3篇
  2011年   4篇
  2010年   3篇
  2009年   1篇
  2008年   4篇
  2007年   5篇
  2006年   9篇
  2005年   3篇
  2004年   2篇
  2003年   7篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   5篇
  1991年   2篇
  1990年   2篇
  1989年   5篇
  1988年   5篇
  1985年   1篇
  1982年   1篇
  1981年   1篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1972年   2篇
排序方式: 共有111条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Endothelial mitochondria, the major site of ATP generation, modulate the intracellular dynamics of reactive oxygen species (ROS), which, in turn, control endothelial function. Adequate oxygen (O(2)) supply is required by endothelial cells (EC). Both hypoxia and hyperoxia may favor the overproduction of ROS leading to oxidative stress, mitochondrial damage and endothelial dysfunction. We investigated the capability and mechanisms of Cellfood? (CF), an antioxidant compound, to modulate O(2) availability and mitochondrial respiratory metabolism and to regulate ROS generated by hypoxia in EC in vitro. Human umbilical vein endothelial cells (HUVEC) and ECV-304 were evaluated for the O(2) consumption using a Clark's electrode. The O(2) consumption rate rose, during the first minutes after CF addition and was associated with increase in mitochondrial oxidative capacity and good cell viability. Similar behaviours were observed when EC were exposed to CF for up to 8 days. The O(2) consumption increased and was accompanied by both intracellular rise of ATP and maintainment of LDH concentration. Hypoxia-induced ROS generation was significantly inhibited by CF, through the up-regulated expression of MnSOD, an anti-oxidant responsible for mitochondrial function preservation. The EC hypoxic response is mediated by the hypoxia master regulator HIF-1alpha whose activation was attenuated by CF, in concomitance with MnSOD up-regulation. Our results suggest a role for CF in improoving respiratory metabolism and in activating anti-oxidant mechanisms in EC, thus preserving endothelial function.  相似文献   
55.
This study, which is part of a research program for the determination of trace element reference levels in various human tissues for the Italian population, presents the concentrations of Se, Hg, Cr, Cs, Sc, Rb, Zn, Fe, Co, and Sb in lung, liver, spleen, and kidney autopsy samples taken from 14 adult subjects of the Italian population who died from accidental causes. Concentrations of the same trace elements are given also for blood and hair samples taken from subjects of the general Italian population and of a population group living in a small coastal town that has an average annual fish consumption well above the national average. The analytical method used was Instrumental Neutron Activation Analysis. The levels and distribution of the trace elements in the various human organs examined are analyzed and discussed.  相似文献   
56.
57.
We studied by immunocytochemistry the expression of adrenomedullin (AM) in the human medulla oblongata, sampled from 13 adult subjects (mean age: 38 years), whose medical history was negative for neurological and neurovascular pathologies. Immunoreactive neurons were found in the medulla oblongata with statistically significant differences among the various nuclei (one-way ANOVA, P < 0.001). The hypoglossal nucleus showed higher AM expression than that of the spinal tract of the trigeminal nerve (P < 0.05), solitary tract nucleus (P < 0.05), nucleus intercalatus (P < 0.05), and area postrema (P < 0.05). The arcuate nucleus and inferior olivary nuclear complex showed lower AM expression than the hypoglossal nucleus (P < 0.001), vestibular nuclei (P < 0.01), cuneate and gracile nuclei (P < 0.05), lateral column of the reticular formation (P < 0.05), and nucleus ambiguous (P < 0.05). Furthermore the nuclei were grouped with reference to their function, into somatic sensitive nuclei, somatic motor nuclei, visceral nuclei, reticular formation, and nuclei involved in cerebellar functions. The ANOVA revealed statistically significant differences (P < 0.001) in mean AM scores among the different groups. Nuclei involved in cerebellar function showed the lowest mean AM score (P < 0.05). The difference in AM score between somatic motor nuclei and visceral nuclei was also statistically significant (P < 0.05). Widespread AM immunoreactivity in the nuclei of the medulla oblongata may account for the role of the peptide in neuronal function and regulation of regional blood flow. Differences in the expression of AM in the nuclei studied indicate the different involvement of AM in neurotransmission and neuromodulation.  相似文献   
58.
Regenerated adrenocortical nodules were obtained by implanting in the musculus gracilis of rats fragments of the capsular tissue of their excised adrenal glands. Five months after operation, transplanted rats showed a slightly elevated blood concentration of adrenocorticotropin (ACTH), a moderately reduced plasma level of corticosterone (PBC) and a very low concentration of circulating aldosterone (PAC). Regenerated nodules were well encapsulated, and from the connective capsule some septa dipped into the parenchyma. Subcapsular-outer (OZ) and inner (IZ) cells were similar to those of the zona fasciculata/zona reticularis (ZF/ZR) of the normal gland; juxta-septal (JZ) cells resembled those of the zona glomerulosa (ZG). Prolonged (14 days) ACTH infusion normalized PBC and caused a conspicuous hypertrophy of transplanted tissue, which was coupled with a marked hypertrophy of ZF/ZR-like OZ and IZ cells and a notable rise in the basal in vitro production of corticosterone. Conversely, ACTH infusion strikingly lowered PAC, reduced the number of ZG-like JZ cells, and decreased both basal and stimulated secretion of 18-hydroxylated steroids by transplants in vitro.  相似文献   
59.
Epidemiological study of bacterial meningitis, particularly those forms susceptible to vaccination, is an indispensable tool in choosing vaccination strategies. Lombardy Region, where approximately 20% of the Italian population resides, has conducted an in-depth study on invasive meningococcal diseases and pneumococcal meningitis using available health statistics and performing a control of single cases to achieve complete knowledge of the phenomenon. The results, relating to the period 2000-2006, indicate limited incidence rates both for the general population and childhood age groups that do not justify hypotheses of a universal offering of the specific vaccines. However, the healthcare system must equip itself with additional tools for the identification of the serogroups and serotypes responsible for disease as a further support for possible choices modifying the current vaccination policies.  相似文献   
60.
Heterochromatin has been traditionally regarded as a genomic wasteland, but in the last three decades extensive genetic and molecular studies have shown that this ubiquitous component of eukaryotic chromosomes may perform important biological functions. In D. melanogaster, about 30 genes that are essential for viability and/or fertility have been mapped to the heterochromatin of the major autosomes. Thus far, the known essential genes exhibit a peculiar molecular organization. They consist of single-copy exons, while their introns are comprised mainly of degenerate transposons. Moreover, about one hundred predicted genes that escaped previous genetic analyses have been associated with the proximal regions of chromosome arms but it remains to be determined how many of these genes are actually located within the heterochromatin. In this overview, we present available data on the mapping, molecular organization and function of known vital genes embedded in the heterochromatin of chromosomes 2 and 3. Repetitive loci, such as Responder and the ABO elements, which are also located in the heterochromatin of chromosome 2, are not discussed here because they have been reviewed in detail elsewhere.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号