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   196303篇
  免费   33990篇
  国内免费   2543篇
耳鼻咽喉   5639篇
儿科学   6530篇
妇产科学   3205篇
基础医学   9246篇
口腔科学   2702篇
临床医学   30982篇
内科学   56172篇
皮肤病学   8102篇
神经病学   19228篇
特种医学   8737篇
外国民族医学   6篇
外科学   47472篇
综合类   818篇
现状与发展   72篇
一般理论   40篇
预防医学   10868篇
眼科学   4484篇
药学   3758篇
中国医学   75篇
肿瘤学   14700篇
  2024年   702篇
  2023年   4946篇
  2022年   1494篇
  2021年   3811篇
  2020年   6549篇
  2019年   2897篇
  2018年   8206篇
  2017年   7998篇
  2016年   9186篇
  2015年   9319篇
  2014年   16743篇
  2013年   17411篇
  2012年   8369篇
  2011年   8536篇
  2010年   12033篇
  2009年   15724篇
  2008年   8638篇
  2007年   6976篇
  2006年   9406篇
  2005年   6626篇
  2004年   5726篇
  2003年   4636篇
  2002年   4625篇
  2001年   4349篇
  2000年   3519篇
  1999年   3793篇
  1998年   4191篇
  1997年   3873篇
  1996年   3728篇
  1995年   3565篇
  1994年   2227篇
  1993年   1828篇
  1992年   1718篇
  1991年   1724篇
  1990年   1344篇
  1989年   1474篇
  1988年   1292篇
  1987年   1144篇
  1986年   1146篇
  1985年   998篇
  1984年   844篇
  1983年   805篇
  1982年   827篇
  1981年   693篇
  1980年   616篇
  1979年   526篇
  1978年   555篇
  1977年   581篇
  1975年   446篇
  1972年   449篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
PURPOSE: The beneficial role of elective neck dissection (END) in the management of high-risk cutaneous squamous cell carcinoma (CSCC) of the head and neck remains unproven. Some surgical specialists suggest that END may be beneficial for patients with clinically node-negative (N0) high-risk CSCC, but there are few data to support this claim. We reviewed the available literature regarding the use of END in the management of both CSCC and head and neck SCC (HNSCC). METHODOLOGY: The available medical literature pertaining to END in both CSCC and HNSCC was reviewed using PubMed and Ovid Medline searches. RESULTS: Many surgical specialists recommend that END be routinely performed in patients with N0 HNSCC when the risk of occult metastases is estimated to exceed 20%; however, patients who undergo END have no proven survival benefit over those who are initially staged as N0 and undergo therapeutic neck dissection (TND) after the development of apparent regional disease. There is a lack of data regarding the proper management of regional nodal basins in patients with N0 CSCC. In the absence of evidence-based data, the cutaneous surgeon must rely on clinical judgment to guide the management of patients with N0 high-risk CSCC of the head and neck. CONCLUSIONS: Appropriate work-up for occult nodal disease may occasionally be warranted in patients with high-risk CSCC. END may play a role in only a very limited number of patients with high-risk CSCC.  相似文献   
42.
43.
44.
45.
A case of Goldenhar’s Syndrome in a 10 year old girl is reported. The unusual features are the absence of epibulbar dermoid which is one of the major hallmarks of the Syndrome and the presence of an associated Cyanotic Heart disease.  相似文献   
46.
Reactive oxygen species: a breath of life or death?   总被引:7,自引:0,他引:7  
New insights into cancer cell-specific biological pathways are urgently needed to promote development of rationally targeted therapeutics. Reactive oxygen species (ROS) and their role in cancer cell response to growth factor signaling and hypoxia are emerging as verdant areas of exploration on the road to discovering cancer's Achilles heel. One of the distinguishing and near-universal hallmarks of cancer growth is hypoxia. Unregulated cellular proliferation leads to formation of cellular masses that extend beyond the resting vasculature, resulting in oxygen and nutrient deprivation. The resulting hypoxia triggers a number of critical adaptations that enable cancer cell survival, including apoptosis suppression, altered glucose metabolism, and an angiogenic phenotype. Ironically, recent investigations suggest that oxygen depletion stimulates mitochondria to elaborate increased ROS, with subsequent activation of signaling pathways, such as hypoxia inducible factor 1alpha, that promote cancer cell survival and tumor growth. Because mitochondria are key organelles involved in chemotherapy-induced apoptosis induction, the relationship between mitochondria, ROS signaling, and activation of survival pathways under hypoxic conditions has been the subject of increased study. Insights into mechanisms involved in ROS signaling may offer novel avenues to facilitate discovery of cancer-specific therapies. Preclinical and clinical evaluation of agents that modify ROS signaling in cancer offers a novel avenue for intervention. This review will cover recent work in ROS-mediated signaling in cancer cells and its potential as a target for developmental therapeutics.  相似文献   
47.
BACKGROUND AND PURPOSE: The catastrophic Chi-Chi earthquake of September 21, 1999 in Taiwan provided a unique opportunity to study the disaster's psychiatric impact on survivors. This study assessed the development of psychiatric disorders among residents in a Taiwanese village near the epicenter of the earthquake within 6 months of the disaster. METHODS: A total of 442 of the 602 actual living residents of Tong-Chi village who were over 16 years of age and were present in the community at the time of the earthquake were included in this population survey. Subjects were interviewed by psychiatrists using the Mini-International Neuropsychiatric Interview and questionnaires to collect demographic information and risk factors for psychiatric disorders 4 to 6 months after the earthquake. RESULTS: The prevalence rates were 9.5% for current major depression, 2.8% for past major depressive episode, and 7.9% for post-traumatic stress disorder (PTSD). Females had significantly higher rates of most psychiatric disorders. After controlling for covariates, the significant risk factors for PTSD were female gender and having sought medical service after the earthquake. Significant risk factors for major depressive episode were divorced/widowed status, education level equal to or below primary school, and prominent house damage. CONCLUSION: This population survey of earthquake disaster survivors found an increased prevalence of psychiatric disorders after exposure to a catastrophic earthquake. These results highlight the need for prompt therapeutic attention to residents of earthquake disaster areas after the event.  相似文献   
48.
BACKGROUND: It has been suggested that herpes zoster may be a marker for occult malignancy. AIM: To examine the emergence of a subsequent cancer diagnosis in patients with and without herpes zoster. DESIGN OF STUDY: Retrospective cohort study. SETTING: Results were based on the database of Intego, an ongoing Belgian general practice-based morbidity registry, covering 37 general practitioners and including about 311 000 patient years between the years 1994 and 2000. METHOD: Survival analysis comparing the emergence of malignancy in patients with and without herpes zoster. RESULTS: The number of patients below the age of 65 years with herpes zoster, cancer or both was too low to draw any sensible conclusions. Above the age of 65 years we identified a significant increase of cancer emergence in the whole group and in females (hazard ratio = 2.65, 95% confidence interval = 1.43 to 4.90), but not in males. No difference could be identified in the first year after the herpes zoster infection. CONCLUSION: Our results do not justify extensive testing for cancer in herpes zoster patients. The association we identified, however, leaves open a number of questions with respect to the physiopathology behind it.  相似文献   
49.
Obese Zucker rats are less responsive than their lean littermates to the effects of cholecystokinin-octapeptide on satiety and pancreatic growth and exocrine function. We hypothesized that the hyperphagia observed in obese Zucker rats may be caused by a decreased pyloric contractile response to cholecystokinin, resulting in an increased rate of gastric emptying, decreased postprandial gastric distention, and thus decreased satiety. Pyloric muscle strips from six obese Zucker rats and six lean littermates were mounted in separate tissue baths and isometric contraction was measured in response to acetylcholine and cholecystokinin-octapeptide. The dose-response curves for acetylcholine-and cholecystokinin-octapeptide-stimulated pyloric muscle contraction were similar for both the obese and the lean rats. (For cholecystokinin, D50 obese=4.0±0.6 nM, D50 lean=3.4±0.2 nM;P=0.16). We conclude that the decreased satiety response to cholecystokinin-octapeptide observed in obese Zucker rats is not secondary to a decreased pyloric responsiveness to cholecystokinin.This work was supported by NIH grant AM28303-03.  相似文献   
50.
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