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   2032618篇
  免费   164261篇
  国内免费   6570篇
耳鼻咽喉   28326篇
儿科学   65657篇
妇产科学   52125篇
基础医学   272052篇
口腔科学   54139篇
临床医学   195943篇
内科学   415666篇
皮肤病学   48170篇
神经病学   163835篇
特种医学   76370篇
外国民族医学   253篇
外科学   323121篇
综合类   42178篇
现状与发展   75篇
一般理论   826篇
预防医学   148854篇
眼科学   48606篇
药学   138863篇
  13篇
中国医学   4776篇
肿瘤学   123601篇
  2021年   19626篇
  2020年   15582篇
  2019年   19466篇
  2018年   30917篇
  2017年   24935篇
  2016年   27553篇
  2015年   30618篇
  2014年   46137篇
  2013年   60826篇
  2012年   72073篇
  2011年   75650篇
  2010年   50294篇
  2009年   50525篇
  2008年   70228篇
  2007年   72798篇
  2006年   75280篇
  2005年   70036篇
  2004年   66910篇
  2003年   62531篇
  2002年   60072篇
  2001年   96767篇
  2000年   97505篇
  1999年   81619篇
  1998年   25433篇
  1997年   22334篇
  1996年   21999篇
  1995年   21146篇
  1994年   18386篇
  1993年   16734篇
  1992年   59656篇
  1991年   57443篇
  1990年   54746篇
  1989年   52625篇
  1988年   47835篇
  1987年   46490篇
  1986年   43818篇
  1985年   41450篇
  1984年   30909篇
  1983年   26325篇
  1982年   15520篇
  1979年   26416篇
  1978年   18503篇
  1977年   15793篇
  1976年   14599篇
  1975年   15231篇
  1974年   18244篇
  1973年   17523篇
  1972年   16271篇
  1971年   14890篇
  1970年   13871篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Despite extensive investigation, the pathogenesis of the adult respiratory distress syndrome (ARDS) remains uncertain. As yet, there is no clear explanation of why some patients at risk for ARDS develop the syndrome, whereas others do not. Neutrophils and complement fragments have been implicated in the acute lung injury, but it is clear from published data that evidence of complement activation alone predicts neither the development nor the severity of ARDS. We investigated whether the combination of endotoxin, a leukocyte-priming agent, and complement fragments, leukocyte-stimulating agents, was associated with the development of ARDS. Ninety-eight patients were identified as being either at risk for the development of ARDS or having ARDS, and serial blood samples were obtained. There was no correlation between C5 fragments and the development of ARDS. C3 fragment levels were increased in 89% of the patients with ARDS, but they were also increased in 62% of patients at risk. Endotoxin was detected in 74% of the plasma samples obtained from patients at risk who subsequent developed ARDS and in 64% of the plasma samples obtained from the patients with ARDS. In contrast, only 22% of the plasma samples obtained from the patients at risk who did not develop ARDS had measurable endotoxin. We suggest that the combination of endotoxin and complement fragments may be one mechanism involved in the development of ARDS.  相似文献   
995.
996.
In a study of rock music preferences, listening/watching behavior, and views on destructive rock lyrics, 894 adolescents in grades 9 through 12 in rural, urban, suburban public, and metropolitan parochial schools were administered a questionnaire. Demographic information on parents was also collected. It was found that 17.5% of the students were fans of rock music with lyrics that promote homicide, suicide, or satanic practices (HSSR). Loglinear and multiple regression analyses were used to analyze the data. Parents' marital status, student sex, race, and school environment (urban, rural, suburban, etc.) were found to be significant predictors of HSSR status. As compared with non-HSSR fans, the HSSR fans were more likely to have parents who were “Never married” or “Remarried” and less likely to have parents in the “married” category. The HSSR fans were more likely to be male, white, and enrolled in urban schools but not parochial schools than expected; HSSR status also significantly predicted other music-related attitudes and behaviors. The HSSR fans reported liking both the sound and the lyrics of rock music more often than did non-HSSR fans, as did females and urban students. The HSSR fans more often felt that children under 10 years of age should be allowed to listen to HSSR lyrics, and they more frequently expressed the conviction that HSSR music does not affect adolescents' homicidal or self-destructive behavior. The HSSR fans and females reported more nearly complete knowledge of lyrics than did non-HSSR fans and males. The HSSR fans reported that they watch more MTV than did any other group except rural students.  相似文献   
997.
While the family's primacy in the patient's adaptation to chronic illness increasingly is being recognized by health professionals and social scientists, the reverse side of the coin, that is, the impact of chronicity on the family, has received little attention. A life-span development perspective is used to enrich the more traditional frameworks employed to study family development and also as a unifying framework from which to view the impact of illness on individual family members and the family as a unit. A review of selected literature reveals a profile of families most at risk for serious disruption in situations involving chronic illness. Propositions suggesting interventions directed at patients and families experiencing chronicity are derived.  相似文献   
998.
Head trauma     
Computed tomography is currently the modality of choice in imaging acutely traumatized patients. This is based upon CT's documented ability to detect surgically significant lesions. Furthermore, the use of MRI is limited by a lack of bone detail, the degradation of MR images in frequently uncooperative patients, and a limited supply of nonferromagnetic monitoring equipments. CT and MRI are largely equivalent in their ability to diagnose epidural hematoma, but CT is readily available and quick. MRI provides information in addition to that obtained by CT in many instances, such as subacute and chronic subdural hematomas, contusions, and intracerebral hematomas.  相似文献   
999.
STUDY OBJECTIVE: To evaluate the hemodynamic effects of the antiarrhythmic drug, encainide, in patients with severe chronic heart failure. DESIGN: Unblinded, before-after study. SETTING: Referral center for patients with heart failure. PATIENTS: Thirty patients with severe chronic heart failure and a left ventricular ejection fraction less than 40%. INTERVENTIONS: Invasive hemodynamic measurements were done (using a balloon-tipped thermodilution catheter) before and for 3 hours after a single oral dose of 50 mg of encainide. MEASUREMENTS AND MAIN RESULTS: Ninety to one hundred and twenty minutes after its administration, encainide produced a significant deterioration in cardiac performance, as reflected by a fall in cardiac index from 2.3 to 1.8 L/min.m2 body surface (mean change 0.5 +/- 0.1; P less than 0.001), a fall in stroke work index from 26 to 18 g.m/m2 (mean change 8 +/- 2; P less than 0.001), and an increase in left ventricular filling pressure from 19 to 22 mm Hg (mean change 3 +/- 2; P less than 0.05). These deleterious hemodynamic effects were accompanied by worsening symptoms of heart failure in 8 of the 30 patients. Serum levels of encainide and its metabolites, O-desmethylencainide and 3-methoxy-O-desmethylencainide, were within the therapeutic range in most patients. CONCLUSIONS: Encainide can cause adverse hemodynamic and clinical effects in patients with severe chronic heart failure.  相似文献   
1000.
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