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   1334183篇
  免费   95953篇
  国内免费   2904篇
耳鼻咽喉   19713篇
儿科学   40226篇
妇产科学   38660篇
基础医学   187205篇
口腔科学   39816篇
临床医学   112622篇
内科学   262380篇
皮肤病学   30205篇
神经病学   106365篇
特种医学   53665篇
外国民族医学   435篇
外科学   208220篇
综合类   31043篇
现状与发展   6篇
一般理论   436篇
预防医学   92032篇
眼科学   31358篇
药学   100049篇
  4篇
中国医学   2987篇
肿瘤学   75613篇
  2018年   11739篇
  2015年   11871篇
  2014年   16686篇
  2013年   25239篇
  2012年   32998篇
  2011年   34859篇
  2010年   20728篇
  2009年   20226篇
  2008年   33569篇
  2007年   36675篇
  2006年   37251篇
  2005年   36003篇
  2004年   35088篇
  2003年   34059篇
  2002年   33586篇
  2001年   63613篇
  2000年   65322篇
  1999年   55387篇
  1998年   14650篇
  1997年   13458篇
  1996年   12937篇
  1995年   12221篇
  1994年   11467篇
  1992年   42761篇
  1991年   41280篇
  1990年   40553篇
  1989年   39550篇
  1988年   36963篇
  1987年   36408篇
  1986年   34899篇
  1985年   33101篇
  1984年   24822篇
  1983年   21052篇
  1982年   12664篇
  1981年   11568篇
  1980年   10772篇
  1979年   23923篇
  1978年   17068篇
  1977年   14835篇
  1976年   13386篇
  1975年   15267篇
  1974年   18080篇
  1973年   17560篇
  1972年   16810篇
  1971年   15717篇
  1970年   14914篇
  1969年   14346篇
  1968年   13460篇
  1967年   12015篇
  1966年   11258篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
221.
OBJECTIVE: The authors examined 1) rates of trauma and posttraumatic stress (PTS) in older adults in primary care; 2) factors related to more posttraumatic stress symptoms; and 3) the influence of posttraumatic stress and depression on health perceptions and negative health behaviors (i.e., suicidal ideation, smoking, and at-risk drinking). METHODS: As part of participation in a study at the Philadelphia VAMC and the University of Pennsylvania, a random subset (N = 2,718) of older adults (age > or = 65 years) with scheduled primary care visits were screened concerning demographics, the General Health Questionnaire-12, suicidal thoughts, alcohol consumption, cigarette smoking, perceived health status, PTS, and cognitive impairment. RESULTS: The rate of trauma in older adult primary care patients was high in both the VA (37%) and university-based clinics (24%). Many older adults reported interference from at least one of the three posttraumatic stress items assessed (VA, 18%; university-based primary care, 8%). In a model including demographic factors, higher PTS and depression were uniquely related to more negative health perceptions. In a model including demographic factors, both higher PTS and depression were uniquely related to higher likelihood of suicidal ideation. In contrast, PTS no longer contributed to a model of smoking once depression was included. Neither PTS nor depression significantly contributed to a model of at-risk drinking. CONCLUSIONS: Trauma and posttraumatic stress are frequent and significant problems for older adults in primary care. Both posttraumatic stress and depression are related to more negative health perceptions and higher likelihood of suicidal ideation.  相似文献   
222.
223.
To determine if impaired energy metabolism might contribute to some aspects of Alzheimer disease (AD), including the vulnerability of the CA1 region of the hippocampal formation and the altered cytoskeleton evident in neurofibrillary tangles, we examined the effects of metabolic poisons on neuronal damage and cytoskeletal disruption in the hippocampal formation. Intrahippocampal injection of 3-nitropropionic acid (3-NP) and malonic acid resulted in neuronal death, particularly in CA1. Cytoskeletal disruption included loss of dendritic MAP2, but sparing of axonal τ. MK-801 (a noncompetitive NMDA receptor antagonist) did not atenuate the lesions produced by intrahippocampal injection of malonate. MK-801, however, was effective against intrastriatal malonate. Acute systemic 3-NP resulted in neuronal damage and cytoskeletal disruption in the CA1 region of the hippocampal formation, including an extensive loss of MAP2 immuno-reactivity, but sparing of τ. The neuronal loss in CA1 was delayed as compared to striatum. Chronic intraventricular infusion of 3-NP produced a different pattern of neuronal damage. Loss of τ-1 immuno-reactivity was observed in CA3 and CA1 s. oriens, whereas MAP2 immunostaining was preserved. These results demonstrate that chronic and acute administration of metabolic inhibitors produce distinct patterns of neuronal damage and cytoskeletal disruption. The results further suggest a differential involvement of the NMDA receptor in malonate-induced neuronal damage in striatum as compared to the hippocampus. The pattern of neuronal damage and cytoskeletal disruption observed following acute metabolic impairment resembled some aspects of neurofibrillary pathology in AD, but did not result in τ hyperphosphorylation.  相似文献   
224.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
225.
目的:过去15年在慢性胰腺炎(CP)的内镜治疗中取得了巨大进展。然而,经内镜行胰腺内放置支架的价值还有争议。材料与方法:对98例(84例男性,14例女性,年龄49±12岁,极差23~83)有症状的CP患进行包括胰管内临时支架的内镜下介入治疗。将最后支架取出时作为内镜治疗的主要研究终点,96例患共随访了35±28个月(极差8d~111个月),对所有数据进行回顾性分析。结果:与其他的内镜下操作一样,共有358个支架放置在胰管内且留置了3±1个月(极差1d~11个月)。总的支架治疗时间是10±10个月(极差6d~49个月)。在有限的内镜治疗后的46±27个月(极差4~111个月)中,57例患不需要再次介入治疗,甚至2/3患没有更多的疼痛感。在22例需要外科治疗和17例需要再次内镜治疗的患中明显与继续摄入乙醇有关。结论:临时支架植入作为CP患内镜介入治疗的一部分有较高的技术含量和长期临床成功率,而且在相当多患中不需要二次治疗。禁止乙醇摄入明显有助于治疗效果的维持。  相似文献   
226.
Purpose We report a case of periocular subcutaneous macrofilariasis as an initial sign of a systemic Loa loa infection.Methods Thorough history, eye examination and surgical intervention. Parasitological and serological analysis.Results A periocular adult Loa loa worm was extracted from the left upper eyelid in an African student living in Germany after presenting to our department with intermittent attacks of painful lid swelling. Four weeks later he presented with Calabar swellings in his arms without serological evidence of microfilaria and was treated with diethylcarbamazine.Conclusion Due to increasing migration of populations to Europe rare manifestations of ocular loiasis are becoming more common. Intermittent painful eyelid swelling in patients who visited or have lived in Africa should always raise the suspicion of systemic loiasis.  相似文献   
227.
228.
Setting goals to maintain hope.   总被引:3,自引:0,他引:3  
  相似文献   
229.
230.
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