首页 | 官方网站   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   2895篇
  免费   251篇
  国内免费   163篇
医药卫生   3309篇
  2024年   6篇
  2023年   42篇
  2022年   97篇
  2021年   131篇
  2020年   93篇
  2019年   82篇
  2018年   81篇
  2017年   85篇
  2016年   73篇
  2015年   112篇
  2014年   151篇
  2013年   138篇
  2012年   194篇
  2011年   195篇
  2010年   147篇
  2009年   140篇
  2008年   144篇
  2007年   159篇
  2006年   145篇
  2005年   127篇
  2004年   112篇
  2003年   76篇
  2002年   80篇
  2001年   57篇
  2000年   56篇
  1999年   54篇
  1998年   65篇
  1997年   71篇
  1996年   50篇
  1995年   50篇
  1994年   31篇
  1993年   33篇
  1992年   24篇
  1991年   15篇
  1990年   18篇
  1989年   22篇
  1988年   24篇
  1987年   21篇
  1986年   12篇
  1985年   13篇
  1984年   6篇
  1983年   7篇
  1982年   12篇
  1981年   5篇
  1980年   9篇
  1978年   8篇
  1977年   6篇
  1976年   8篇
  1975年   6篇
  1974年   3篇
排序方式: 共有3309条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Functional neuroimaging studies have detected abnormal limbic and paralimbic activation to emotional probes in posttraumatic stress disorder (PTSD), but few studies have examined neurochemical mechanisms that underlie functional alterations in regional cerebral blood flow. The mu-opioid neurotransmitter system, implicated in responses to stress and suppression of pain, is distributed in and is thought to regulate the function of brain regions that are implicated in affective processing. METHODS: Here we examined the micro-opioid system with positron emission tomography and the micro-opioid receptor-selective radiotracer [11C] carfentanil in 16 male patients with PTSD and two non-PTSD male control groups, with (n = 14) and without combat exposure (n = 15). Differences in micro-opioid receptor binding potential (BP2) were detected within discrete limbic and paralimbic regions. RESULTS: Relative to healthy controls, both trauma-exposed groups had lower micro-opioid receptor BP2 in extended amygdala, nucleus accumbens, and dorsal frontal and insular cortex but had higher BP2 in the orbitofrontal cortex. PTSD patients exhibited reduced BP2 in anterior cingulate cortex compared with both control groups. Micro-opioid receptor BP2 in combat-exposed subjects without PTSD was lower in the amygdala but higher in the orbitofrontal cortex compared with both PTSD patients and healthy controls. CONCLUSIONS: These findings differentiate the general response of the micro-opioid system to trauma from more specific changes associated with PTSD.  相似文献   
2.
AIM: To determine the incidence of Type 2 diabetes and to examine the effect of different cut-points for impaired fasting glucose (IFG) on diabetes incidence. METHODS: Population-based longitudinal study (1990-2000) with clinical, anthropometric and biochemical measurements, including an oral glucose tolerance test (OGTT), in 1040 non-diabetic adults aged 40-69 years at baseline. Baseline glucose status was defined as normoglycaemia < 5.6, IFG-lower 5.6-6.0 and IFG-original 6.1-6.9 mmol/l. The all-IFG group included fasting glucose values of 5.6-6.9 mmol/l. RESULTS: The 10-year cumulative incidence of diabetes was 7.3 per 1000 person-years. Diabetes incidence was 2.4 [95% confidence interval (CI) 1.2, 4.8], 6.2 (4.0, 9.8) and 17.5 (12.5, 24.5) per 1000 person-years in those with normoglycaemia, IFG-lower and IFG-original, respectively. Compared with normoglycaemia, the age/sex-adjusted risk [hazard ratio (HR) and 95% CI] for incident diabetes was greatest in the IFG-original category (HR 6.9; 3.1, 15.2) and increased to a lesser degree in the IFG-lower (HR 2.5; 1.1, 5.7) and all-IFG categories (HR 4.1; 1.9, 8.7). When adjusted for confounding factors, the magnitude and direction of associations persisted, with HR 1.9, 4.4 and 2.9, for the categories IFG-lower, IFG-original and all-IFG, respectively. CONCLUSIONS: Diabetes incidence is more strongly related to IFG defined as fasting glucose between 6.1 and 6.9 mmol/l than to the lower category of 5.6-6.0 mmol/l, or entire range of 5.6-6.9 mmol/l. Future studies should examine the association of IFG with cardiovascular outcomes, but for diabetes risk our study supports the use of the IFG cut-point at 6.1 mmol/l.  相似文献   
3.
4.
用混合粘合剂碳糊电极测定丁螺环酮   总被引:6,自引:1,他引:5  
用混合粘合剂碳糊电极测定丁螺环酮张正奇,曾鸽鸣,刘传桂,黎艳飞(湖南大学化学化工系,长沙410082)碳糊电极无毒,制作方便,表面更新容易,应用电位范围广,在药物分析中已有应用[1~5]。我们在液体石腊中加入添加剂,组成混合粘合剂,可显著改善电极的检...  相似文献   
5.
6.
Triptolide is potent immunosuppressive has been reported to inhibit autoimmunity, compound isolated from Chinese herbal medicine. Triptolide allograft attributed to the suppression of T cells via NF - kB rejection and GVHD, and its efficacy was previously pathway and apoptosis. In the present study, we detailedly analyzed Triptolide' s function on murine primary T cell. We found that Triptolide could inhibit T cell activation and proliferation by dramatically down - regulating cell division and cell cycle. Triptolide inhibited T cell activation in a dose- dependent manner, and the inhibition was mediated by both NF- kB pathway and AP - 1 pathway.  相似文献   
7.
报告120例羊膜腔穿刺羊水细胞培养结果:在成功的99例中,发现二例染色体异常,核型为47,xy,+18和46,xx/47,xx,+F,在21例失败中出现一例眼球畸形。培养成功率为82.5%;染色体异常检出率为2.02%。无一例因羊膜腔穿刺而导致流产,但出现一例轻度羊水栓塞合并症。并对羊水细胞培养在产前宫内诊断中应用价值及术后并发症进行了讨论。  相似文献   
8.
应用声振仪对1992年2个月~1993年6个月单胎36~43周妊娠孕妇150例进行了声音振动刺激试验(VAS-T)并与无负荷试验(NST)对照。对此结果VAS-T(+)146例,(-)4例,NST反应型96例,无反应型54例。NST无反应型预测价值8%,假阴性率92%。NST无反应型经声音刺激后50例成VAS-T(+)。VAS-T预测价值99.3%。NST有效率66%,VAS-T有效率99%。NST至少需做20min,VAS-T95%在3min内达到标准,最长15min。为避免NST假无反应型,应进行VAS-T。  相似文献   
9.
11例TH胶胃冠状静脉栓塞术临床治疗结果表明:(1)11例中的4例急性上消化道大出血患者均在12h左右出血基本停止,随访近一年未再发生出血现象。(2)10例半年后复查肝功能均有不同程度改善。(3)一年后复查食道钡餐透视X线平片发现8例患者食道静脉曲张有不同程度减轻。(4)11例中1例因术中急性肝功能衰竭死亡。因此我们认为此术式操作简便,手术创伤小、较易推广,是治疗门脉高压症合并食管胃底静脉曲张出血的一种有效方法。  相似文献   
10.
Y Niv  C Turani  E Kahan  GM Fraser 《Gastroenterology》1997,112(6):2104-2107
Polycystic kidney disease is an autosomal dominant disease that may be associated with cystic disease of the liver. In women, the cysts may develop early and be more troublesome than in men. Cystadenocarcinoma of the pancreas is uncommon, comprising 1% of primary pancreatic malignancies. This case report is the first to describe a familial association between polycystic kidney disease and cystadenocarcinoma of the pancreas and liver in the English medical literature. A patient with autosomal dominant polycystic kidney disease (ADPKD) and multiple hepatic cysts developed cystadenocarcinoma of the pancreas with multiple malignant liver cysts. The patient's mother, sister, and niece had ADPKD, and the patient's sister also died of pancreatic cystadenocarcinoma. We believe that the development of these two disease entities in which the primary pathology is cyst formation has a genetic association. (Gastroenterology 1997 Jun;112(6):2104-7)  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-23

京公网安备 11010802026262号