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   27038篇
  免费   1997篇
  国内免费   66篇
耳鼻咽喉   246篇
儿科学   798篇
妇产科学   553篇
基础医学   3312篇
口腔科学   404篇
临床医学   2678篇
内科学   5342篇
皮肤病学   722篇
神经病学   2379篇
特种医学   1046篇
外国民族医学   1篇
外科学   4121篇
综合类   420篇
一般理论   60篇
预防医学   2314篇
眼科学   860篇
药学   1819篇
中国医学   31篇
肿瘤学   1995篇
  2022年   212篇
  2021年   403篇
  2020年   260篇
  2019年   391篇
  2018年   477篇
  2017年   411篇
  2016年   435篇
  2015年   491篇
  2014年   768篇
  2013年   1088篇
  2012年   1623篇
  2011年   1672篇
  2010年   954篇
  2009年   848篇
  2008年   1584篇
  2007年   1621篇
  2006年   1599篇
  2005年   1652篇
  2004年   1609篇
  2003年   1505篇
  2002年   1481篇
  2001年   409篇
  2000年   318篇
  1999年   352篇
  1998年   345篇
  1997年   317篇
  1996年   290篇
  1995年   272篇
  1994年   238篇
  1993年   236篇
  1992年   281篇
  1991年   251篇
  1990年   229篇
  1989年   230篇
  1988年   204篇
  1987年   193篇
  1986年   188篇
  1985年   224篇
  1984年   215篇
  1983年   217篇
  1982年   248篇
  1981年   256篇
  1980年   212篇
  1979年   168篇
  1978年   178篇
  1977年   169篇
  1976年   115篇
  1975年   132篇
  1974年   143篇
  1973年   110篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
BACKGROUND: Brain serotonin neurotransmission and hypothalamic-pituitary-adrenal axis function are implicated in the pathophysiology of depression, and these systems interact in a reciprocal modulatory fashion. This study examined the effect of tryptophan depletion, which acutely reduces brain serotonin concentrations, on serial cerebrospinal fluid concentrations of corticotropin-releasing factor in healthy humans. METHODS: Five subjects completed a standard tryptophan depletion protocol, and four subjects participated in a comparison condition. Subjects underwent continuous sampling of cerebrospinal fluid via lumbar peristaltic pump. Concentrations of cerebrospinal fluid corticotropin-releasing factor were measured by radioimmunoassay. RESULTS: No mood changes were observed in either group. Tryptophan-depleted subjects exhibited significantly greater increases in corticotropin-releasing factor concentrations over time than subjects in the comparison condition. CONCLUSIONS: These findings highlight the potential importance of corticotropin-releasing factor and serotonin interactions and suggest that activation of corticotropin-releasing-factor-containing neurons could play a role in the emergence of mood symptoms following tryptophan depletion in vulnerable individuals.  相似文献   
992.
ABSTRACT: BACKGROUND: The purpose of the study is to describe the impact of oral health-related quality of life (OHRQoL) on the lives of pre-seniors and seniors living in Nova Scotia, Canada. METHODS: This cross-sectional study involved 1461 participants, grouped by age (pre-seniors [45-64] and seniors [65+]) and residential status (long-term care facility [LTC] or community). OHRQoL was measured using the 14-item Oral Health Impact Profile questionnaire (OHIP-14) in a random digit dialing telephone survey (for community residents) or a face-to-face interview (for LTC residents). Intra-oral examinations were performed by one of six dentists calibrated to W.H.O. standards. RESULTS: Approximately one in four pre-seniors and seniors reported at least one OHRQoL impact 'fairly/very often'. The most commonly reported impacts were within the dimensions 'physical pain' and 'psychological discomfort'. It was found that 12.2% of LTC residents found it uncomfortable to eat any foods 'fairly/very' often compared to 7.7% in the community, and 11.6% of LTC residents reported being self-conscious 'fairly/very often' compared to 8.2% in the community. Of those residing in the community, pre-seniors (28.8%) reported significantly more impacts than seniors (22.0%); but there were no significant differences in OHRQoL between pre-seniors (21.2%) and seniors (25.3%) in LTC. Pre-seniors living in the community scored significantly higher than community dwelling seniors on prevalence, extent and severity of OHIP-14 scores. Logistic regression revealed that for the community dwelling sample, individuals living in rural areas in addition to those being born outside of Canada were approximately 2.0 times more likely to report an impact 'fairly/very often', whereas among the LTC sample, those having a high school education or less were 2.3 times more likely to report an impact. CONCLUSIONS: Findings indicate that the oral health and OHRQoL of both pre-seniors and seniors in LTC residents is poor. Community dwelling pre-seniors have the highest prevalence rate of oral impacts.  相似文献   
993.
994.

Background  

Colonic stents are used chiefly for malignant large-bowel obstruction as a palliative measure or bridge to surgery that facilitates one-step resections. Literature on colorectal stenting demonstrates good safety and efficacy; however, a recent trial has raised concerns regarding the safety of a new large-diameter stent, especially in the setting of concurrent chemotherapy. This study evaluated our experience with colorectal stenting using mainly this stent.  相似文献   
995.
The trans-oral approach allows direct access to pathologies of the anterior craniocervical junction. However, the classic midline incision of the posterior pharyngeal wall can be surgically burdensome and limits lateral exposure. We reviewed the medical records of nine patients undergoing the trans-oral approach. The sites of the pathology ranged from the clivus to C2, and surgical exposure ranged from the clivus to C3. Each operation utilized an inferiorly based flap. None of the patients experienced vascular or neurologic complications, and no patient had a cerebrospinal fluid fistula, pseudomeningocele, or meningitis postoperatively. The trans-oral approach with an inferiorly based flap can therefore be safely and effectively performed with minimal oropharyngeal and neurologic morbidity. Not only does a U-shaped flap allow adequate exposure from the lower half of the clivus to C3, a flap improves lateral exposure, provides a clear operating field, and allows superficial mucosal closure not directly overlying the operative field.  相似文献   
996.
997.
998.
999.
1000.
Historically, poliovirus infection has been an important cause of acute flaccid paralysis (AFP) worldwide; however, successful elimination of wild-type poliovirus in much of the world has highlighted the importance of other causes of AFP. Despite the evolving etiology, AFP surveillance in most developing countries still focuses on poliovirus detection and fails to detect many AFP cases, particularly among adults. We assessed 41 subjects self-reporting symptoms suggestive of AFP during a population-based health survey in the Department of Santa Rosa, Guatemala. Thirty-five (85%) of the suspected cases were not hospitalized. Most subjects (37) did not have features consistent with AFP or had other diagnoses explaining weakness. We identified two adults who had not received medical attention for a clinical illness consistent with Guillain-Barré syndrome, the most important cause of non-poliovirus AFP. Usual surveillance methods for AFP, particularly in developing countries, may underestimate the true burden of non-poliovirus AFP.  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