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   1085033篇
  免费   81435篇
  国内免费   3004篇
耳鼻咽喉   14679篇
儿科学   37475篇
妇产科学   30394篇
基础医学   156838篇
口腔科学   30617篇
临床医学   96339篇
内科学   214945篇
皮肤病学   26123篇
神经病学   86409篇
特种医学   40309篇
外国民族医学   306篇
外科学   160661篇
综合类   24491篇
一般理论   411篇
预防医学   86438篇
眼科学   24641篇
药学   77938篇
  5篇
中国医学   2648篇
肿瘤学   57805篇
  2021年   9998篇
  2019年   10160篇
  2018年   14144篇
  2017年   10400篇
  2016年   11365篇
  2015年   12648篇
  2014年   17432篇
  2013年   26440篇
  2012年   35509篇
  2011年   37901篇
  2010年   22334篇
  2009年   20404篇
  2008年   34022篇
  2007年   35867篇
  2006年   36020篇
  2005年   34715篇
  2004年   33556篇
  2003年   32177篇
  2002年   30785篇
  2001年   49292篇
  2000年   50828篇
  1999年   42224篇
  1998年   11772篇
  1997年   10586篇
  1996年   10544篇
  1995年   10122篇
  1994年   9372篇
  1993年   8701篇
  1992年   32784篇
  1991年   31883篇
  1990年   31430篇
  1989年   30203篇
  1988年   27502篇
  1987年   27625篇
  1986年   25698篇
  1985年   24855篇
  1984年   18578篇
  1983年   15687篇
  1982年   9416篇
  1979年   17005篇
  1978年   12332篇
  1977年   10374篇
  1976年   9831篇
  1975年   10241篇
  1974年   12419篇
  1973年   11921篇
  1972年   10950篇
  1971年   10201篇
  1970年   9441篇
  1969年   8809篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Maximum anchorage often presents a problem that is difficult to solve during orthodontic tooth movement. Stationary, skeletal anchorage can be achieved in a simple, minimally-invasive manner, and unwanted tooth movements in opposite directions can be prevented by using transmucosally-inserted bone screws.Our initial experience using the FAMI screw as an orthodontic micro-implant proved to be clinically and histologically successful.  相似文献   
992.
993.
994.
To evaluate use of a digital photostimulable phosphor imaging system in the neonatal nursery, 150 newborns were divided into three groups of 50. In the first two groups, screen-film and computed radiographs of the chest were obtained at the same radiation exposure; in the third group, computed radiographs were obtained with a 50% dose reduction (half-exposure computed radiographs). All images were blindly evaluated by three readers who scored the quality of visualization of the mediastinum, lung, bone, soft tissues, and endotracheal and nasogastric tubes, and also image density. No statistical differences in visualization of tubes existed among the three groups. Visualization of the mediastinum, lung, bones, and soft tissues was statistically significantly better on computed radiographs than on half-exposure computed radiographs; visualization of the lungs, bones, and soft tissues was statistically significantly better on screen-film radiographs than half-exposure computed radiographs. Image density was statistically better on computed and half-exposure computed radiographs than on screen-film radiographs.  相似文献   
995.
Although there are well-established clinical human milk banks in the United States, there are no milk banks specifically intended to foster research on human milk. The authors' goal was to establish a milk bank with a core data set to support exploratory and hypothesis-driven studies on human milk. Donations to the Cincinnati Children's Research Human Milk Bank are accepted within the context of ongoing, hypothesis-driven research or on an ad hoc basis. Donors must give informed consent, and scientists wishing to use the samples must have Institutional review board approval for their use. Development of more research human milk banks can potentially provide resources for multidisciplinary collaboration and advance the study of human milk and lactation.  相似文献   
996.
The study presented here was conducted to evaluate the performance of the newly available RIDASCREEN Set (R-Biopharm AG, Darmstadt, Germany) for the detection of immunoglobulin G antibodies against Entamoeba histolytica. The sensitivity and specificity of this new enzyme-linked immunosorbent assay were evaluated using a panel of sera from 239 individuals. The assay was positive for 43 of 44 patients with invasive amebiasis, including all 18 patients with amebic liver abscess, while it was negative for 190 of 195 adult controls who were either healthy individuals or patients with other parasitic diseases. The kit was found to be highly specific (97.4%) and sensitive (97.7%) for detecting antibodies against E. histolytica in humans. Although antibody titers in patients with amebic liver abscess tend to be higher on average than in patients with invasive amebiasis, it is not possible to distinguish the two forms solely based on the results of this commercial test.  相似文献   
997.
OBJECTIVE: The aim of the study was to describe the occurrence of spontaneous version in twins in the third trimester, as well as the correlation between antepartum and birth presentation. METHODS: Twin pregnancies were divided into four gestational age intervals: 20-23; 24-27; 28-31; and 32-36 weeks. Fetal presentation was categorized as cephalic (C) or non-cephalic (NC). Hospital records were reviewed to determine demographic factors, including mode of conception. Chi-square was used to compare distributions of presentations, and Cramer's V measure of association was used to correlate presentations in individual pregnancies between antepartum intervals and birth. RESULTS: A total of 207 pregnancies were included. The distribution of fetal presentations changed significantly through gestational age intervals (p < 0.001), although they were similar between 32-36 weeks and birth (p = 0.75). Correlation between antepartum and birth presentation in individual pregnancies strengthened throughout the four intervals. No correlation was seen between parity, gender, birthweight, or in vitro fertilization and fetal presentation or rate of spontaneous version.CONCLUSION: Many twins undergo spontaneous version in the third trimester, though there is excellent correlation between presentation at 32-36 weeks and birth. A cephalic presenting twin at > or = 28 weeks is highly likely to be in cephalic presentation at delivery.  相似文献   
998.
The ratio of growth hormone response to clonidine and L-dopa challenge was compared in 74 boys: 15 with purported physical abuse, 7 with purported sexual abuse, 13 normal controls, and 39 psychiatric controls. Sexually abused boys demonstrate a statistically significant elevated ratio of growth hormone response to clonidine versus response to L-dopa. Physically abused boys demonstrate lower clonidine/L-dopa growth hormone response ratios compared with controls. These effects widen with increasing physical development.  相似文献   
999.
Crisis debriefing of a jury after a murder trial   总被引:1,自引:0,他引:1  
The importance of crisis debriefing for those involved in major accidents, violent crimes, and natural disasters has been demonstrated. Similar debriefing may be warranted for jurors exposed to disturbing material in criminal cases. The authors describe a debriefing session for jurors after the murder trial of a man whose truck had collided with a school bus, killing 27 people. The graphic evidence of the accident, the high levels of emotion of the survivors and the victims' relatives, and the intense community and national attention to the trial placed the jurors under considerable stress. The debriefing enabled the jurors to express their feelings of anger, guilt, and frustration and to begin to accept their role in the event.  相似文献   
1000.
Two experiments examined the ingestive responses of streptozotocin-diabetic rats fed low-fat or high-fat diets to glucose, fructose, sucrose and maltose solutions in brief (30 min) intake tests. In Experiment 1, one-bottle acceptability tests were used whereas two-bottle preference tests were used in Experiment 2. Three main findings resulted from these studies. Firstly, diabetic rats fed the low-fat diet displayed a reduced acceptance of and preference for all concentrated sugar solutions. Secondly, glucose consumption patterns of diabetic rats fed the low-fat diet were distinctly different from their responses to the other sugars. Thirdly feeding high-fat diets, either high or low in carbohydrate, normalized the responses of diabetic rats to the sugar solutions. The results suggest that feeding high-fat diets to diabetic rats normalizes their responses to sugar solutions because of reductions in hunger and thirst associated with the provision of a utilizable source of calories and an improvement in body fluid balance.  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