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   367篇
  免费   13篇
  国内免费   3篇
儿科学   18篇
妇产科学   44篇
基础医学   40篇
口腔科学   1篇
临床医学   49篇
内科学   79篇
皮肤病学   3篇
神经病学   26篇
特种医学   49篇
外科学   25篇
预防医学   15篇
眼科学   3篇
药学   14篇
肿瘤学   17篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   3篇
  2019年   6篇
  2018年   7篇
  2016年   7篇
  2015年   15篇
  2014年   11篇
  2013年   18篇
  2012年   13篇
  2011年   16篇
  2010年   7篇
  2009年   9篇
  2008年   13篇
  2007年   17篇
  2006年   17篇
  2005年   14篇
  2004年   16篇
  2003年   13篇
  2002年   15篇
  2001年   6篇
  2000年   8篇
  1999年   11篇
  1998年   9篇
  1997年   12篇
  1996年   12篇
  1995年   8篇
  1994年   6篇
  1993年   7篇
  1992年   7篇
  1991年   6篇
  1990年   3篇
  1989年   5篇
  1988年   8篇
  1987年   11篇
  1986年   10篇
  1985年   2篇
  1983年   3篇
  1982年   1篇
  1981年   2篇
  1980年   4篇
  1979年   1篇
  1978年   4篇
  1977年   1篇
  1976年   3篇
  1974年   1篇
  1970年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有383条查询结果,搜索用时 15 毫秒
101.
The epidemiological scenarios of hepatitis E virus (HEV) and hepatitis A virus (HAV) infections have changed in the last few decades, but precise epidemiological data on the prevalence of anti-HEV and anti-HAV, alone or in combination, in the general population are scanty. We investigated HEV and HAV seroprevalence comparing two population samples living in Northern (Abbiategrasso, Milan) and Southern Italy (Cittanova, Reggio Calabria), the latter being characterized by a poorer socio-economic level and hygienic/sanitary conditions. Based on census records, we randomly enrolled and tested 3,365 subjects (Abbiategrasso, n?=?2,489; Cittanova, n?=?876) aged 18–75 years for anti-HAV and anti-HEV. Anti-HAV (71.3 % vs 52.5 %) and anti-HEV (17.8 % vs 9.0 %) prevalence rates were higher in Southern Italy (both p?<?0.001). Most anti-HEV-positive subjects also had anti-HAV. Subjects testing positive for anti-HAV, alone or with anti-HEV, were older (p?<?0.001 in both populations) and showed a trend toward declining prevalence in the youngest birth cohorts. The prevalence of subjects with a positive result for anti-HEV alone did not change in birth cohorts in the two towns. Detection of anti-HEV was independently associated with anti-HAV, town, birth cohort, and education level in multivariate analysis. Low socio-economic level and hygienic/sanitary conditions are associated with high HAV and HEV seroprevalence rates in Italy. Recent improvements, especially in the South, have led to a declining prevalence of anti-HAV, alone or with anti-HEV. Seroprevalence of HEV alone is uniformly low and does not change in birth cohorts born between 1938 and 1993.  相似文献   
102.
103.

Aim

Intrahepatic cholestasis of pregnancy (ICP) is characterized by pruritus and elevated bile acid concentrations in maternal serum. This is accompanied by an enhanced risk of intra-uterine and perinatal complications. High concentrations of sulphated progesterone metabolites (PMS) have been suggested to be involved in the multifactorial aetiopathogenesis of ICP. The aim of this study was to investigate further the mechanism accounting for the beneficial effect of oral administration of ursodeoxycholic acid (UDCA), which is the standard treatment, regarding bile acid and PMS homeostasis in the mother-placenta-foetus trio.

Method

Using HPLC-MS/MS bile acids and PMS were determined in maternal and foetal serum and placenta. The expression of ABC proteins in placenta was determined by real time quantitative PCR (RT-QPCR) and immunofluorescence.

Results

In ICP, markedly increased concentrations of bile acids (tauroconjugates > glycoconjugates >> unconjugated), progesterone and PMS in placenta and maternal serum were accompanied by enhanced concentrations in foetal serum of bile acids, but not of PMS. UDCA treatment reduced bile acid accumulation in the mother-placenta-foetus trio, but had no significant effect on progesterone and PMS concentrations. ABCG2 mRNA abundance was increased in placentas from ICP patients vs. controls and remained stable following UDCA treatment, despite an apparent further increase in ABCG2.

Conclusion

UDCA administration partially reduces ICP-induced bile acid accumulation in mothers and foetuses despite the lack of effect on concentrations of progesterone and PMS in maternal serum. Up-regulation of placental ABCG2 may play an important role in protecting the foetus from high concentrations of bile acids and PMS during ICP.  相似文献   
104.
The term retained products of conception (RPOC) refers to intrauterine tissue that develops after conception and persists after medical and surgical pregnancy termination, miscarriage, and vaginal or cesarean delivery. One of the most important factor risk for RPOC is placenta accreta, defined as “the abnormal adherence, either in whole or in part, of the afterbirth to the underlying uterine wall”. We report a case of a 37 years old woman referred to our gynecologic department with irregular vaginal bleeding. On her medical history, she had a cesarean occurred 3 months before. Ultrasonography revealed in the uterine cavity hyperechoic mass, treated with curettage. Two weeks later the curettage, patient complained still vaginal bleeding. On the transvaginal ultrasound, the uterine cavity was occupied again by a hyperechoic mass. She underwent to hysteroscopic resection and histological diagnosis was compatible with placenta accreta residual. In the follow up she had not complications. Early diagnosis, prompt evaluation of bleeding is important for timely treatment and for preventing immediate complications and demolitive approach. A careful follow up is necessary to prevent late consequences. The purpose of this study is to report our experience in timely diagnosis and conservative management.  相似文献   
105.
BACKGROUND & AIMS: Murine autoimmune gastritis, induced by day-3 thymectomy, is characterized by cellular infiltrates and circulating autoantibodies to gastric hydrogen/potassium adenosine triphosphatase. The aim of this study was to analyze the cellular infiltrates and cytokines in autoimmune gastritis. METHODS: Stomachs and blood samples from day-3 thymectomized BALB/c mice were obtained from 2 to 12 weeks after thymectomy for analysis. RESULTS: At 4 weeks, the gastritic infiltrates were composed of macrophages and CD4+ T cells, accompanied by major histocompatibility complex class II expression on gastric epithelial cells. Mucosal B cells, scant at 4 weeks, were abundant at 8 weeks, coincident with the peaking of autoantibodies to gastric hydrogen/potassium adenosine triphosphatase. CD8+ T cells increased marginally during the 12 weeks. Mononuclear cells from diseased stomachs transferred gastritis to nu/nu recipients. At 4 weeks, interleukins 2, 3, 5, 6, and 10; interferon gamma; tumor necrosis factor alpha; and granulocyte-macrophage colony-stimulating factor were detected in gastritic mucosa, but interleukin 4 was not. CONCLUSIONS: The early lesion of autoimmune gastritis is composed of macrophages and CD4+ T cells with major histocompatibility complex class II expression in gastric epithelial cells. Autoantibody production is a late event. Our results are consistent with a lesion mediated by CD4+ T cells producing a mix of Th1- and Th2-type cytokines. (Gastroenterology 1996 Jun;110(6):1791-802)  相似文献   
106.
OBJECTIVE: To assess possible differences in the activity of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and their inhibitors, the tissue inhibitors of MMPs, TIMP-1 and TIMP-2, in follicular fluid (FF) of women undergoing in vitro fertilization (IVF) treatment and of normally ovulating women. DESIGN: Prospective study. METHODS: MMP-2 and MMP-9 activity was analyzed by gelatin zymography and MMP-2, MMP-9, TIMP-2, TIMP-1 and 17beta-estradiol levels were measured in FF by ELISA. RESULTS: We found significantly reduced MMP levels in FF of women undergoing IVF treatment when compared with those of normally ovulating women. In contrast, the TIMP-1 levels were found significantly increased in FF from IVF patients vs normally ovulating women. No significant differences were found for TIMP-2 between the two groups. CONCLUSIONS: These findings underline a marked difference in MMPs and their inhibitors in the IVF women and the control group. Therefore we assume MMPs depend on hormonal steroidogenesis modulation induced by the gonadotropin protocol for IVF treatment.  相似文献   
107.
108.
109.
Gupta IR, Ryan AK. Claudins: unlocking the code to tight junction function during embryogenesis and in disease. Claudins are the structural and molecular building blocks of tight junctions. Individual cells express more than one claudin family member, which suggests that a combinatorial claudin code that imparts flexibility and dynamic regulation of tight junction function could exist. Although we have learned much from manipulating claudin expression and function in cell lines, loss‐of‐function and gain‐of‐function experiments in animal model systems are essential for understanding how claudin‐based boundaries function in the context of a living embryo and/or tissue. These in vivo manipulations have pointed to roles for claudins in maintaining the epithelial integrity of cell layers, establishing micro‐environments and contributing to the overall shape of an embryo or tissue. In addition, loss‐of‐function mutations in combination with the characterization of mutations in human disease have demonstrated the importance of claudins in regulating paracellular transport of solutes and water during normal physiological states. In this review, we will discuss specific examples of in vivo studies that illustrate the function of claudin family members during development and in disease.  相似文献   
110.
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