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   2344684篇
  免费   171774篇
  国内免费   5790篇
耳鼻咽喉   32175篇
儿科学   77575篇
妇产科学   66867篇
基础医学   343638篇
口腔科学   65375篇
临床医学   215744篇
内科学   451991篇
皮肤病学   47881篇
神经病学   189533篇
特种医学   87809篇
外国民族医学   696篇
外科学   342170篇
综合类   51073篇
现状与发展   2篇
一般理论   730篇
预防医学   188512篇
眼科学   53211篇
药学   176004篇
  7篇
中国医学   5045篇
肿瘤学   126210篇
  2018年   25212篇
  2017年   18973篇
  2016年   20984篇
  2015年   24040篇
  2014年   33184篇
  2013年   51225篇
  2012年   70253篇
  2011年   74958篇
  2010年   43949篇
  2009年   40846篇
  2008年   70254篇
  2007年   75004篇
  2006年   75797篇
  2005年   73769篇
  2004年   70579篇
  2003年   67727篇
  2002年   66189篇
  2001年   103820篇
  2000年   106508篇
  1999年   90077篇
  1998年   25961篇
  1997年   23430篇
  1996年   23364篇
  1995年   22109篇
  1994年   20843篇
  1993年   19438篇
  1992年   72427篇
  1991年   71349篇
  1990年   69692篇
  1989年   67044篇
  1988年   62267篇
  1987年   60817篇
  1986年   58137篇
  1985年   55619篇
  1984年   41779篇
  1983年   35932篇
  1982年   21685篇
  1981年   19230篇
  1979年   39019篇
  1978年   27647篇
  1977年   23316篇
  1976年   22468篇
  1975年   23856篇
  1974年   28557篇
  1973年   27843篇
  1972年   26144篇
  1971年   24262篇
  1970年   22596篇
  1969年   21276篇
  1968年   20101篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
ABSTRACT: Background: Although increases in perinatal mortality risk associated with fetal macrosomia are well documented, the optimal route of delivery for fetuses with suspected macrosomia remains controversial. The objective of this investigation was to assess the risk of neonatal death among macrosomic infants delivered vaginally compared with those delivered by cesarean section. Methods: Data were derived from the U.S. 1995–1999 Linked Live Birth‐Infant Death Cohort files and term (37–44 wk), single live births to United States resident mothers selected. A proportional hazards model was used to analyze the risk of neonatal death associated with cesarean delivery among 3 categories of macrosomic infants (infants weighing 4,000–4,499 g; 4,500–4,999 g; and 5,000+ g). Results: After controlling for maternal characteristics and complications, the adjusted hazard ratio for neonatal death associated with cesarean delivery among the 3 categories of macrosomic infants was 1.40, 1.30, and 0.85. Conclusions: Although cesarean delivery may reduce the risk of death for the heaviest infants (5,000+ g), the relative benefit of this intervention for macrosomic infants weighing 4,000–4,999 g remains debatable. Thus, policies in support of prophylactic cesarean delivery for suspected fetal macrosomia may need to be reevaluated. (BIRTH 33:4 December 2006)  相似文献   
52.
53.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  相似文献   
54.
OBJECTIVE: To explore the impact of timing and type of ultrasound, particularly three-dimensional (3D), exposure on maternal-fetal attachment and maternal health behavior during pregnancy. METHODS: Subjects were 68 women aged 18 years or older expecting their first child who presented for a routine ultrasound scan at around either 12 or 18 weeks' gestation in Nepean Hospital, Western Sydney. Women completed questionnaires assessing maternal-fetal attachment and health behavior, and were then allocated arbitrarily to either two-dimensional (2D) or 3D ultrasound examination. Repeat questionnaires were completed 1 week later. RESULTS: Maternal-fetal attachment increased after both 2D and 3D ultrasound exposure, and the effect was moderated by the timing of exposure, with women receiving their first ultrasound examination at around 12 weeks showing the greatest change. Alcohol consumption was the only behavior to show significant change following ultrasound exposure, with a reduction in the reported average number of drinks per week. There was no significant difference in the pattern of change for 2D compared with 3D ultrasound exposure, and no effect of ultrasound exposure on maternal perception of the fetus. CONCLUSIONS: Ultrasound has a positive impact on maternal-fetal attachment, particularly in the first trimester. 3D ultrasound did not offer enhanced benefits. Associations between ultrasound exposure and alcohol consumption warrant further investigation. Larger samples are needed to clarify the moderating effects of gestational age and type of ultrasound exposure.  相似文献   
55.
56.
57.
58.
59.
Neu-Laxova syndrome (NLS) is a rare autosomal recessive syndrome, characterized by severe intrauterine growth retardation (IUGR), microcephaly, abnormal brain development, oedema and ichthyosis. It was first reported in 1971 by Neu et al. (Pediatrics 47: 610-612) and since then no more than 60 cases have been reported. A newborn girl delivered from a 29-year-old healthy mother was admitted to hospital with a thick membrane covering her body and dismorphic appearance. The diagnosis of NLS was made according to characteristic features. The syndrome is known to have a poor prognosis and the baby lived for 9 weeks. This case is one of the longest living cases of NLS and the fourth case reported from Turkey.  相似文献   
60.
Leocani  L.  Comi  G. 《Neurological sciences》2006,27(1):s27-s29
Neurological Sciences - Brain plasticity, intended as the pattern of functional and structural changes in responses to environmental physiological or pathological events, is underlined by several...  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