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   84205篇
  免费   8348篇
  国内免费   188篇
耳鼻咽喉   1203篇
儿科学   2529篇
妇产科学   1801篇
基础医学   11902篇
口腔科学   2054篇
临床医学   10431篇
内科学   14712篇
皮肤病学   1323篇
神经病学   6787篇
特种医学   2821篇
外国民族医学   10篇
外科学   11560篇
综合类   1955篇
一般理论   67篇
预防医学   9639篇
眼科学   1867篇
药学   6972篇
  1篇
中国医学   105篇
肿瘤学   5002篇
  2021年   1117篇
  2020年   742篇
  2019年   1125篇
  2018年   1393篇
  2017年   1018篇
  2016年   1096篇
  2015年   1400篇
  2014年   1826篇
  2013年   2703篇
  2012年   3583篇
  2011年   3956篇
  2010年   2064篇
  2009年   2044篇
  2008年   3300篇
  2007年   3697篇
  2006年   3511篇
  2005年   3518篇
  2004年   3283篇
  2003年   3042篇
  2002年   2967篇
  2001年   2731篇
  2000年   2830篇
  1999年   2510篇
  1998年   1075篇
  1997年   895篇
  1996年   882篇
  1995年   795篇
  1994年   821篇
  1993年   752篇
  1992年   2105篇
  1991年   2034篇
  1990年   1903篇
  1989年   1866篇
  1988年   1776篇
  1987年   1788篇
  1986年   1692篇
  1985年   1664篇
  1984年   1388篇
  1983年   1256篇
  1982年   845篇
  1981年   722篇
  1979年   1217篇
  1978年   871篇
  1977年   761篇
  1976年   715篇
  1975年   715篇
  1974年   859篇
  1973年   753篇
  1972年   734篇
  1971年   641篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
Hollingworth described chewing gum as ‘a technique of relaxation’. Recent research has examined this issue and there is evidence that chewing gum can prevent the adverse effects of acute stress. There are also plausible biological mechanisms that could explain such effects. It is now important to examine chewing gum and chronic stress and the present study involved a survey of this topic. The survey covered the ‘stress process’, collecting data on exposure to stressful events, levels of perceived stress and health outcomes. Frequency of chewing gum was also recorded. Potential confounding factors (demographics, personality and health-related behaviours) were also recorded. The web-based survey was completed by a community sample of 2,248 full-time workers (68% female. Mean age: 35 years, range 18–74 years). Sixty-one per cent of the sample were gum chewers. The results showed that chewing gum was associated with lower levels of perceived stress (both at work and life in general). Gum chewers were also less likely to be depressed and to have seen their doctor for high blood pressure or high cholesterol. Chewing gum was associated with lower levels of alcohol consumption and with cigarette smoking. Gum chewers were also more likely to be neurotic extraverts. Those who chewed gum were also more likely to be exposed to negative factors at work. Logistic regression analyses showed that the effects of chewing gum on stress and health remained significant when these confounding factors were controlled for. These results suggest that chewing gum may be a simple way of preventing stress and the negative health outcomes that are often associated with it. Intervention studies are now required and the mechanisms underlying the effects reported here need further investigation. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
84.
Cholangiocarcinomas (CC) frequently demonstrate lymphatic spread. We investigated lymph node (LN) counts after resection of extrahepatic CC and survival based on the SEER 1973–2004 database. Out of 20,068 CC patients, 1,518 individuals were selected based on M0 stage and at least one LN examined. Primary cancer sites included gallbladder (29%), extrahepatic bile ducts (26%), and intrapancreatic/ampullary bile ducts (45%); 42% of patients were LN-positive. The median number of LNs examined was four (range 1–39). Median survival was 37 months for LN-negative and 16 months for LN-positive cancers. Multivariate prognostic variables were the number of positive LNs, primary site, age (all at p < 0.0001), gender (p = 0.002), size (p = 0.005), T category (p = 0.009), and total LN count (or number of negative LNs obtained, p = 0.01). The impact of total LN counts was seen in LN-negative (median survival, 1 vs 10 or more LNs examined: 27 vs 51 months, p = 0.002) and LN-positive disease (10 vs 22 months, p < 0.0001). Survival prediction of extrahepatic CCs is strongly influenced by total LN counts and numbers of negative LNs obtained. Although the resulting incremental benefit is small, dissection and examination of 10 or more LNs should be considered for curative intent resections.  相似文献   
85.
86.
87.
88.
Objective Approximately 10% of patients with neurofibromatosis I (NFI) patients will have central nervous system (CNS) tumors. The most common of these are hypothalamic–optic gliomas, followed by brainstem and cerebellar pilocytic astrocytomas. While isolated pilocytic astrocytomas in NFI are well described, the appearance of multiple pilocytic astrocytomas in an individual patient is less common. The most frequent combination in NFI patients with more than one pilocytic astrocytoma is optic tract/hypothalamic and brainstem. Other combinations are exceedingly rare; multiple pilocytic astrocytomas have only been reported once in the cerebral hemispheres in a patient with NFI. This report presents the first documented case, to our knowledge, of multiple pilocytic astrocytomas in the cerebellum of a patient with NF1. Methods Case report. Conclusion The finding of multiple cerebellar pilocytic astrocytomas in a patient with NF1 is important because it expands the spectrum of presentations for patients with NF1 and also highlights specific diagnostic and therapeutic challenges faced by the treating physicians. The genetic and molecular basis of NF1 is reviewed. Strategies of diagnosis and treatment outlined here are relevant to both patients with NF1 and all patients with multiple posterior fossa tumors.  相似文献   
89.
90.
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