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   726篇
  免费   21篇
  国内免费   6篇
儿科学   33篇
妇产科学   9篇
基础医学   109篇
口腔科学   46篇
临床医学   29篇
内科学   174篇
神经病学   57篇
特种医学   9篇
外科学   179篇
综合类   1篇
预防医学   7篇
眼科学   4篇
药学   37篇
肿瘤学   59篇
  2023年   6篇
  2022年   7篇
  2021年   12篇
  2020年   11篇
  2019年   11篇
  2018年   12篇
  2017年   9篇
  2016年   9篇
  2015年   9篇
  2014年   20篇
  2013年   23篇
  2012年   35篇
  2011年   26篇
  2010年   23篇
  2009年   19篇
  2008年   32篇
  2007年   36篇
  2006年   44篇
  2005年   33篇
  2004年   32篇
  2003年   31篇
  2002年   41篇
  2001年   13篇
  2000年   8篇
  1999年   22篇
  1998年   8篇
  1997年   4篇
  1996年   7篇
  1994年   5篇
  1993年   10篇
  1992年   13篇
  1991年   10篇
  1990年   17篇
  1989年   19篇
  1988年   9篇
  1987年   10篇
  1986年   10篇
  1985年   12篇
  1984年   12篇
  1983年   8篇
  1982年   4篇
  1979年   7篇
  1978年   9篇
  1977年   7篇
  1976年   4篇
  1973年   6篇
  1971年   7篇
  1969年   3篇
  1968年   4篇
  1967年   6篇
排序方式: 共有753条查询结果,搜索用时 15 毫秒
61.

Purpose  

The effects of mild and moderate hypothermic therapy on cerebral injury are still controversial. Our hypothesis is that mild and moderate hypothermia should have some effects on neurons themselves if they really have protective effects. By using a nearly pure neuronal culture, we evaluated the effects and mechanism of hypothermia against hypoxic insult.  相似文献   
62.
Background  The effect of obesity on gastrectomy in patients with gastric cancer is controversial. The degree of abdominal fat increases the technical difficulty of abdominal surgery. This study examined the effect of visceral fat on total gastrectomy and risk factors associated with the formation of pancreatic fistula. Methods  Between February 2001 and April 2007, 191 patients with gastric cancer underwent total gastrectomy. The visceral fat area (VFA) was calculated from computed tomography (CT) scans taken at the level of the umbilicus using FatScan Software. Patients were divided into high- (≥100 cm2, n = 52) and low-VFA groups (<100 cm2, n = 139), and also into high- (≥25 kg/m2, n = 47) and low-BMI groups (<25 kg/m2, n = 144). Results  Blood loss and incidence of pancreatic fistula were significantly higher in the high- than low-VFA group. However, only blood loss was significantly different between the high- and low-BMI groups. VFA, blood loss, and splenectomy were identified as significant risk factors for pancreatic fistula formation on univariate analysis, and multivariate logistic regression analysis of these factors identified VFA (p = 0.0001) and splenectomy (p = 0.0014) as significant predictors of pancreatic fistula. Conclusions  VFA is a better indicator for pancreatic fistula formation after total gastrectomy than is BMI. Lymph node dissection must be performed carefully, especially in patients with visceral fat accumulation during total gastrectomy with splenectomy.  相似文献   
63.
The aim of this study was to compare the initial and long-term outcomes of sirolimus-eluting stents (SES) and bare-metal stents (BMS) in patients with calcified lesions without performing rotational atherectomy. The subjects were 79 consecutive lesions (38 in the SES group and 41 in the BMS group) which were confirmed to have superficially calcified lesions by intravascular ultrasound. In all lesions, the stent was implanted after predilatation with a balloon. The patient characteristics were not different between the 2 groups. All procedures were successfully performed in both groups. Vessel area was significantly smaller in the SES group than in the BMS group (11.01 +/- 3.88 mm(2) versus 13.08 +/- 3.49 mm(2), P < 0.005), as was the lumen area (5.41 +/- 2.31mm(2) versus 6.48 +/- 2.04 mm(2), P < 0.005). Minimum stent area was significantly smaller in the SES group than in the BMS group (5.61 +/- 1.54 mm(2) versus 6.69 +/- 1.74 mm(2), P < 0.01). In cases in whom angiographic follow-ups were performed, the late loss was significantly smaller in the SES group than in the BMS group (0.19 +/- 0.49 mm versus 0.76 +/- 0.48 mm, P < 0.001). The restenosis rate was significantly lower in the SES group than in the BMS group (8.8% versus 33.3%, P < 0.05) and the TLR rate tended to be lower in the SES group (7.9% versus 19.5%). Stent thrombosis was not observed in either group. The results suggest that SES are more effective than BMS and can be used safely when treating calcified lesions if predilatation with a balloon is possible.  相似文献   
64.
65.
Intraductal papillary-mucinous carcinoma (IPMC) is a recently recognized pancreatic tumor and this is the first report to present two patients with IPMC complicating tumor thrombi in the portal vein. Two women, a 74- and a 55-year-old, each revealed a round, cystic and well-demarcated tumor of the pancreas in an abdominal computed tomography (CT). However, the inner lumen of the splenic and portal veins was insufficiently stained during iv-infusion of the contrast medium, suggesting the presence of tumor thrombi. Owing to this information, the presence of tumor thrombus was investigated and correctly identified during laparotomy, and it was completely removable together with the primary pancreatic tumor. The resected tumors showed expansive growth because mucin and tumor tissues rose up when they were cut. Microscopically, the tumor was diagnosed as adenocarcinoma without ovarian-like stroma, and the final diagnosis of branch type of IPMC was made for the two patients. However, within one postoperative year, both patients developed liver metastasis. Although IPMC is known as having a lower potential for metastasis or invasion, the tumor thrombi can form when it reveals an expansive growth suggesting a high inner pressure. In addition, a higher possibility for subsequent liver metastasis should be anticipated after the tumor forms a thrombus in the portal vein.  相似文献   
66.
67.
Insulin and insulin-like growth factor 1 (IGF1) are ubiquitous growth factors that regulate proliferation in most mammalian tissues including pancreatic islets. To explore the specificity of insulin receptors in compensatory beta-cell growth, we examined two models of insulin resistance. In the first model, we used liver-specific insulin receptor knockout (LIRKO) mice, which exhibit hyperinsulinemia without developing diabetes due to a compensatory increase in beta-cell mass. LIRKO mice, also lacking functional insulin receptors in beta-cells (beta IRKO/LIRKO), exhibited severe glucose intolerance but failed to develop compensatory islet hyperplasia, together leading to early death. In the second model, we examined the relative significance of insulin versus IGF1 receptors in islet growth by feeding high-fat diets to beta IRKO and beta-cell-specific IGF1 receptor knockout (beta IGFRKO) mice. Although both groups on the high-fat diet developed insulin resistance, beta IRKO, but not beta IGFRKO, mice exhibited poor islet growth consistent with insulin-stimulated phosphorylation, nuclear exclusion of FoxO1, and reduced expression of Pdx-1. Together these data provide direct genetic evidence that insulin/FoxO1/Pdx-1 signaling is one pathway that is crucial for islet compensatory growth response to insulin resistance.  相似文献   
68.

Purpose

Homozygous mutant Ncx/Hox11L.1-deficient (Ncx−/−) mice develop mega-ileo-ceco-colon with a caliber change in the proximal colon. This study investigated the mechanism of intestinal motility in these mice.

Method

Five-week-old male and female Ncx−/− mice with mega-ileo-ceco-colon (n = 8) were compared with age-matched male BDF1 mice used as controls (n = 8). All mice were sacrificed, and uniform-sized strips of jejunum, ileum, proximal colon, and distal colon were exposed to electrical field stimulation and pretreatment with atropine sulfate, guanethidine, or tetrodotoxin. Contractile responses were recorded and compared.

Results

Longitudinal muscle from strips of jejunum and ileum from all mice (BDF1 and Ncx−/−) did not respond to electrical field stimulation, whereas ileal circular muscle contracted in BDF1 mice and contracted and relaxed in Ncx−/− mice. Pretreatment with atropine sulfate and guanethidine inhibited the responses of circular muscle of distal colon and ileum in BDF1 mice significantly (P < .05), but no effect was observed in Ncx−/− mice.

Conclusion

In ileum, BDF1 mice have cholinergic and adrenergic dominant contraction patterns, whereas Ncx−/− mice have relaxation-dominant patterns because of nonadrenergic, noncholinergic nerves. Based on this, there would appear to be some kind of variation in the gastrointestinal nerve supply in Ncx−/− mice.  相似文献   
69.
Olfactory information is initially processed through intricate synaptic interactions between glutamatergic projection neurons and GABAergic interneurons in the olfactory bulb. Although bulbar neurons and networks have been reported to develop even postnatally, much is yet unknown about the glutamatergic neuron development. To address this issue, we studied the postnatal ontogeny of vesicular glutamate transporters (VGLUT1 and VGLUT2) in the main olfactory bulb of rats, using in situ hybridization, immunohistochemistry, and their combination. In situ hybridization data showed that VGLUT1 mRNA is intensely expressed in differentiating mitral cells and smaller cells of the mitral cell layer (MCL) on postnatal day 1 (P1), and also at lower levels in small- and medium-sized cells, presumably tufted cell populations, of the external plexiform layer (EPL) from P5 onward. VGLUT2 mRNA was expressed in many MCL cell populations on P1, also in small- and medium-sized cells of the EPL at almost the same level as MCL cells between P5 and P7, and became apparently less intense in the MCL than in the EPL from P10 onward. The expression, unlike VGLUT1 mRNA, was also found in small-sized cells of the interglomerular region. In partial agreement with these data, immunohistochemical analyses demonstrated that subsets of mitral and EPL cells are stained for VGLUT1 or VGLUT2, with the former cells coexpressing both subtypes until P5. Moreover, a combined fluorescence in situ hybridization–immunohistochemical dual labeling of the P10 bulb revealed that neither VGLUT1 nor VGLUT2 mRNA is expressed in GABAergic or dopaminergic periglomerular cells, implying their expression in other periglomerular cell subclasses, external tufted cells and/or short-axon cells. Thus, the present study suggests that early in the postnatal development distinct glutamatergic bulbar neurons of rats express spatiotemporally either or both of the two VGLUT subtypes as a specific vesicular transport system, specifically contributing to glutamate-mediated neurobiological events.  相似文献   
70.
To determine the optimal timing for influenza vaccination in pregnant women, we measured alterations in the types 1 and 2 T helper cell (Th1/Th2) balance during pregnancy, monitored specific immunity to inoculated antigens after vaccination with inactivated influenza vaccine, evaluated the relevance of the Th1/Th2 ratio and immune responses to the vaccination, monitored the maintenance of high antibody titers until delivery and measured the transplacental antibody transfer rate. No significant alterations of the Th1/Th2 balance were noted in the 65% of pregnant women among whom the Th1/Th2 ratio was lower than 9.9% in the first trimester. In those groups with a ratio higher than 10% in the first trimester, there was a tendency for the ratio to decrease as gestation advanced. The efficiency of immunization was not influenced by the Th1/Th2 status or by the stage of gestation. The antibody titer decreased steadily with time from 1 month after vaccination to the time of delivery. Conversely, the transfer rate of antibodies from maternal to fetal blood at the time of delivery increased with the duration of gestation after vaccination. Nevertheless, the antibody titers in both maternal and fetal blood were sufficient to afford protection against infection. Thus, efficient influenza vaccination can be undertaken at any stage of pregnancy. J. Med. Virol. 81:1923–1928, 2009. © 2009 Wiley‐Liss, Inc.  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