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   12598篇
  免费   1322篇
  国内免费   55篇
耳鼻咽喉   260篇
儿科学   360篇
妇产科学   290篇
基础医学   1634篇
口腔科学   342篇
临床医学   1510篇
内科学   2706篇
皮肤病学   197篇
神经病学   941篇
特种医学   477篇
外科学   1761篇
综合类   431篇
一般理论   7篇
预防医学   1307篇
眼科学   207篇
药学   917篇
中国医学   6篇
肿瘤学   622篇
  2022年   104篇
  2021年   176篇
  2020年   133篇
  2019年   185篇
  2018年   188篇
  2017年   177篇
  2016年   153篇
  2015年   224篇
  2014年   255篇
  2013年   394篇
  2012年   539篇
  2011年   539篇
  2010年   288篇
  2009年   272篇
  2008年   477篇
  2007年   548篇
  2006年   508篇
  2005年   504篇
  2004年   479篇
  2003年   506篇
  2002年   455篇
  2001年   392篇
  2000年   470篇
  1999年   355篇
  1998年   179篇
  1997年   143篇
  1996年   147篇
  1995年   133篇
  1994年   120篇
  1993年   107篇
  1992年   295篇
  1991年   296篇
  1990年   267篇
  1989年   285篇
  1988年   234篇
  1987年   228篇
  1986年   262篇
  1985年   227篇
  1984年   190篇
  1983年   150篇
  1982年   128篇
  1979年   184篇
  1978年   120篇
  1977年   119篇
  1975年   125篇
  1974年   145篇
  1973年   135篇
  1972年   141篇
  1971年   121篇
  1970年   110篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
PURPOSE: To profile adolescent Internet chat room users in terms of demographic characteristics, psychological and environmental factors, and behavioral risk factors. METHODS: The study sample was drawn from respondents to an anonymous statewide survey of 50,168 9th-grade public school students and included 40,376 students who reported Internet access at home and 19,511 who accessed chat rooms. Data were collected by the Minnesota Student Survey (MSS), a survey that has been administered triennially by the state's education department to public school students in grades 6, 9, and 12 since 1989. The MSS includes more than 117 questions (300 variables) addressing attitudinal, behavioral, and environmental issues. Data analysis consisted of comparing the odds of a particular characteristic or behavior for chat room users with that of nonusers. Analyses were run separately for boys and girls. The homogeneity of odd ratios was tested with the Breslow-Day statistic using SPSS for Windows. RESULTS: For boys and girls, use of Internet chat rooms was associated with psychological distress, a difficult living environment, and a higher likelihood of risky behaviors. Although most chat room users did not report serious problems, this group included a disproportionate number of troubled individuals. CONCLUSIONS: Because chat room use serves as an indicator of heightened vulnerability and risk-taking, parents and others need to be aware of potential dangers posed by online contact between strangers and youth.  相似文献   
62.
A glutathione conjugate of amodiaquine has been isolated and characterized from rat bile after administration of [14C]amodiaquine (50 mumol/kg, 5.0 muCi/rat) to anaesthetized male Wistar rats. Thioether conjugates of amodiaquine in rat bile accounted for a total of 12% of the dose, 5 hr after administration of the drug. In addition, 1% of the dose remained in the liver covalently bound to tissue proteins after 5 hr. These findings provide direct evidence that a chemically reactive metabolite, amodiaquine quinoneimine, has been formed from the drug in vivo. A second major metabolite, desethylamodiaquine, accounting for 14% of the given dose, was present in the liver after 5 hr. Enzyme inhibition studies with ketoconazole-pretreated rats showed that both amodiaquine quinoneimine and desethylamodiaquine formation can be catalysed by cytochrome P450. The demonstration that amodiaquine readily and extensively forms a metabolite in vivo, with strong reactivity towards protein and non-protein thiol groups, may help to explain the idiosyncratic toxicity observed in man.  相似文献   
63.
An accident at an oil refinery in Texas City, Texas, released around 40,000 lb of hydrogen fluoride, exposing the community to the highly toxic and corrosive substance. A population-based epidemiologic study was conducted to evaluate the impact of the accident on the health of the community. Exposure assessment was done using a multipronged approach through a door-to-door survey of 10,811 individuals. A symptom survey resulting in 1994 completed interviews was conducted with a stratified random sample selected from the exposure study database. The sampling was balanced with respect to age, gender, and predisposition across the three ordinal exposure categories. The results show a strong dose relationship (P < 10(-4)) between the exposure and symptoms reported following the accident and 2 years later, most notably breathing and eye symptoms. However, substantial improvement in health was reported over the 2-year period regardless of the level of exposure. Problems of recall bias and behavioral sensitization are considered and it is recognized that the study may have overestimated the effect. It is also recognized that the study may not have completely unraveled the relative importance of exposure and host response in health outcome, since the two were probably conflated in the exposure measure. Nevertheless, the independence of predisposition and reported level of exposure, the magnitude of effect and its consistency, the unmistakable dose response, the large sample size, and the mutual corroboration of various findings make it difficult to dismiss the interpretation that the hydrofluoric acid exposure indeed caused health problems in the community that continued for at least 2 years after the accident.  相似文献   
64.
65.
66.
67.
Early hepatic artery thrombosis after orthotopic liver transplantation results in massive injury to hepatocytes and the bile duct epithelium. In the fulminate form, impaired liver synthetic function is expressed by encephalopathy and coagulopathy. Ischemic bile duct injury is associated with the disruption of the biliary anastomosis, bile duct strictures, and intrahepatic bilomas. The inability of the liver macrophages to clear translocated portal blood intestinal pathogens results in persistent bacteremia and sepsis. The major radiologic finding is the radiographic evidence of gas gangrene of the liver graft. Early recognition and correct interpretation of the radiologic findings, immediate removal of the liver graft, and placement of the patient on venous-venous bypass or total hepatic devascularization while a new liver is being procured and retransplantation are the only hope for survival.  相似文献   
68.
This critical feminist grounded theory study examined how employed mothers coped with the stress of managing multiple responsibilities in family, health, and paid work. Over a 2-year period, 20 mothers employed as support staff in a large, publicly funded institution participated in repeated individual in-person and telephone interviews and in a focus group. Interviews were transcribed and analyzed using constant comparative methods. The women experienced stress from continuous demands in paid and family health work compounded by time constraints, inflexible expectations, conflicting demands, compromised personal resources, and inadequate support. Most of their coping strategies were individual, such as focusing on priorities, but some women used shared family decision-making. Findings support both individual and family stress and coping theory, yet underscore the need to explicate social-ecological influences such as relational power. Strategies that can enhance coping and reduce stress are described for nurses who work with women and families.  相似文献   
69.
70.
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