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   151篇
  免费   0篇
  国内免费   5篇
  2022年   1篇
  2018年   2篇
  2017年   1篇
  2015年   1篇
  2014年   2篇
  2013年   7篇
  2012年   5篇
  2011年   4篇
  2010年   5篇
  2009年   1篇
  2008年   1篇
  2007年   2篇
  2006年   2篇
  2005年   2篇
  2004年   4篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1997年   3篇
  1996年   2篇
  1995年   4篇
  1994年   7篇
  1993年   1篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1986年   5篇
  1985年   12篇
  1984年   16篇
  1983年   14篇
  1982年   14篇
  1981年   3篇
  1980年   4篇
  1979年   4篇
  1978年   4篇
  1977年   3篇
  1976年   1篇
排序方式: 共有156条查询结果,搜索用时 31 毫秒
141.
Two leptin receptor single nucleotide polymorphisms, Lys109Arg and Gln223Arg, have been shown to associate with several risk factors for cardiovascular disease. In addition, we have previously shown that Arg109 and Arg223 homozygotes displayed lower intima-media thickness in our well-defined OPERA (Oulu Project Elucidating Risk of Atherosclerosis) study. This current research investigated the impact of these LEPR polymorphisms on cardiovascular events and related death as well as to total mortality in the 19-year follow-up of OPERA. Subjects were randomly selected, middle-aged drug-treated hypertensives and their age- and sex-matched control subjects recruited to the OPERA study between 1990 and 1993. Mortality and hospital events of 1045 subjects were followed up until 2009. A total of 151 coronary heart disease (CHD) and 211 cardiovascular disease (CVD) events or deaths including 58 CHD and 69 CVD deaths occurred. Furthermore, during this follow-up, a total of 165 subjects died. Logistic regression analysis was performed to assess the impact of Lys109Arg and Gln223Arg on the events and death. Further modeling was performed with Cox regression for Lys109Arg. The logistic regression analysis revealed a significant protective impact of Arg109Arg genotype on CHD (OR 0.433; CI 95% 0.217–0.863) and CVD (OR 0.540; CI 95% 0.309–0.942) events or death as well as on total mortality (OR 0.390; CI 95% 0.196–0.775) when adjusted with age, sex and study group. Even after further adjustment with BMI, smoking status, systolic blood pressure and low-density lipoprotein cholesterol, the protective effect of Arg109Arg on CHD events or death and total mortality still remained statistically significant (OR 0.463; CI 95% 0.230–0.931 and OR 0.442; CI 95% 0.218–0.896, respectively). Arg109Arg was also shown to confer protection against CHD mortality (HR 0.224; CI95% 0.055–0.919) and overall mortality (HR 0.413; CI95% 0.218–0.783) also in Cox regression analysis. In conclusion, the Arg109Arg genotype of LEPR seems to be protective from cardiovascular events and death and this phenomenon seems to be independent of the traditional risk factors for atherosclerosis.  相似文献   
142.
Immunoreactive cholecystokinin (iCCK), vasoactive intestinal peptide (iVIP) and secretin (iSEC) were determined in the brain and various gut regions in the developing rat between 3 and 28 days after birth and in the adult. From the different patterns observed with these three peptides, it is concluded that in rat neural tissues, peptide concentrations (iCCK in brain, iVIP in brain and gut) increase continuously until about 4 weeks. Concentrations in mucosal tissues (iSEC in gut) are equal to or higher than adult values 3 days after birth. Gut iCCK (found both in neuronal and mucosal tissues) peaks at about 2 weeks, presumably due to concentrations increasing in the former and decreasing in the latter tissues.  相似文献   
143.
In Sinapis alba , a long-day plant (LDP) which can be induced by a single long day (LD), it has been suggested that cytokinins may be part of a multicomponent floral stimulus. In order to determine cytokinin fluxes during floral transition, we developed a technique to collect phloem sap reaching the apical part of the shoot, close to the target bud. Exudates collected from roots, leaves, and the apical part of the shoot were analysed by radioimmunoassay for cytokinins. Such analyses confirm previous observations, obtained using the Amaranthus bioassay. indicating thai cytokinin export from the roots and mature leaves is enhanced 2–5 fold during floral transition. The flux of cytokinins directed to the upper part of the shoot through the phloem is also rapidly increased (ca 1.5–2 fold) by the inductive treatment, between 9 and 25 h after start of the LD. We suggested that the shoot apical merislem of 2-month-old Sinapis plants probably has a low cytokinin level. Induced leaves rapidly produce a signal which is transported to the roots where it alters cytokinin production and/or export. In addition, or as a consequence, leaf-cytokinins are exported via the phloem to the apical meristem where they induce a mitotic peak and some other events normally associated with the floral transition.  相似文献   
144.
Seven peptides derived from pro-somatostatin in rat brain   总被引:7,自引:0,他引:7  
Acid extracts of murine hypothalamic and extra-hypothalamic rat brains were analyzed by specific radioimmunoassays for the presence of somatostatin-14, somatostatin-28 and somatostatin-28(1–12)-like immunoreactivity. Seven molecular forms were observed after gel permeation chromatography. In addition to somatostatin-14, somatostatin-28 and somatostatin-28(1–12), there were two peptides of 4,400 and 7,500 mol. wt. which contained the somatostatin-28(1–12) sequence with an extension towards the NH2-terminus of pro-somatostatin. Moreover, two other peptides of 6,000 and 9,500 mol. wt. were detected containing the whole somatostatin-28 structure. These results imply that the processing of brain pro-somatostatin involves a minimum of four cleavage sites and yields at least seven peptides.  相似文献   
145.
146.
This study was undertaken to assess the nature of somatomedin-C (SM-C) in baboon (Papio cynocephalus) blood and to compare various methods for estimating SM-C concentrations. Parallel dose-response curves were obtained with normal baboon serum, normal human serum, and purified SM-C. Recovery of purified SM-C added to baboon serum over a wide dosage range (n = 17) was 111 ± 12%, with slightly better recovery at higher potencies. Chromatography of normal baboon serum on Sephadex G-200 at neutral pH produced a profile similar to that observed in the human, as did samples chromatographed on Sephadex G-50 in acid. Although the SM-C content in acid chromatographed plasma was approximately 2.5 times higher than in native unprocessed plasma, there was excellent correlation between the values (r = 0.9143, p < 0.0001). The SM-C in baboon plasma which had been preincubated with glycine HCl was approximately twice that of unprocessed plasma, but the correlation between the two methods was excellent (r = 0.9593, p < 0.0001). The correlation between values obtained after simple acid-ethanol extraction and those observed in unextracted plasma were also significant (r = 0.7689, p < 0.0001). Following a series of four injections of human growth hormone (hGH) to a normal baboon, plasma SM-C rose approximately sevenfold above the initial concentration and returned to basal levels five days after the final injection. These studies show that although the radioimmunoassay (RIA) for SM-C in unprocessed baboon plasma does not measure all of the SM-C present, it provides a reliable index of the total SM-C concentration and reflects GH status in the baboon.  相似文献   
147.
Culture medium which was conditioned by tissue of a CE mouse breast tumor in vitro containes dose-dependent osteolytic activity. The osteolytic activity was not soluble in dichloromethane and ethylacetate, indicating that it was not attributable to vitamine D metabolites or prostaglandins. HOwever, breast tumor-conditioned medium stimulated production and release of prostaglandin E2 from mouse calvaria in vitro, and the stimulation of bone resorption in vitro by breast tumor-conditioned medium was blocked by a dose of indomethacin that prevented stimulation of mouse calvarial prostaglandin E2 production and release. The resorptive activity of parathyroid hormone(PTH) was not affected by the same dose of indomethacin, suggesting that the osteolytic factor was not PTH. This was further supported by observation that mouse kidney cell cAMP production was stimulated by PTH, but not only by the aqueous phase of ethylacetate-extracted breast tumor-conditioned medium. In addition to osteolytic activity, breast tumor-conditioned medium contained a dose-dependent bone cell mitogenic activity, demonstrated by the stimulation of [3H]thymidine incorporation into trichloroacetic acid-insoluble macromolecules and a corresponding increase in bone cell number in monolayer cultures of bone cells. Breast tumor-conditioned medium also contained a dose-dependent transforming growth factor-(TGF)-like activity as defined by its ability to transform anchorage-dependent growth of nontransformed cells to anchorage-independent growth. The TGF in breast tumor-conditioned medium did not compete with epidermal growth factor (EGF) for EGF receptor binding, but its transforming activity was greatly enhanced by EGF, indicating that it was a β-type TGF. Both the osteolytic and mitogenic activities were nondialyzable, sensitive to reducing agent, and not removable by dichloromethane and ethylacetate extractions. Furthermore, the TGF activity was not removed by the ethylacetate extraction. Thus, the possibility that these activities in breast tumor-conditioned medium might be mediated by the same molecule must be considered. In summary, our data suggest that the CE mouse mammary carcinoma cells produce and secret into the culture medium an osteolytic factor which is neither PTH nor prostaglandin and which stimulates local synthesis in bone of prostaglandin E2 which in turn increased bone resorption in vitro.  相似文献   
148.
149.
150.
Mallory bodies were isolated from the livers of alcoholic patients obtained at autopsy. The liver tissue was homogenized by a pressure homoge-nizer using nitrogen gas in excess of 2, 000 p. s. i. Solutions of 65% and 70% sucrose were used for discontinuous gradient ultracentrifugation. A distinct band between the two sucrose layers was collected, which was rich in Mallory bodies. Purity of the Mallory body fraction was examined by light and electron microscopy. Mallory body fractions were analyzed for amino acid composition.  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