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   3617098篇
  免费   256095篇
  国内免费   9474篇
耳鼻咽喉   48815篇
儿科学   119956篇
妇产科学   99377篇
基础医学   508264篇
口腔科学   102115篇
临床医学   331244篇
内科学   705192篇
皮肤病学   85351篇
神经病学   292699篇
特种医学   137185篇
外国民族医学   941篇
外科学   540209篇
综合类   77795篇
现状与发展   8篇
一般理论   1392篇
预防医学   276959篇
眼科学   83849篇
药学   264024篇
  12篇
中国医学   7987篇
肿瘤学   199293篇
  2019年   28661篇
  2018年   40856篇
  2017年   31136篇
  2016年   35431篇
  2015年   40139篇
  2014年   55553篇
  2013年   83019篇
  2012年   111903篇
  2011年   118451篇
  2010年   70930篇
  2009年   67335篇
  2008年   110300篇
  2007年   117415篇
  2006年   119035篇
  2005年   114184篇
  2004年   109873篇
  2003年   105669篇
  2002年   102066篇
  2001年   175746篇
  2000年   179885篇
  1999年   151285篇
  1998年   42992篇
  1997年   37867篇
  1996年   37994篇
  1995年   36843篇
  1994年   33680篇
  1993年   31561篇
  1992年   117091篇
  1991年   112934篇
  1990年   109312篇
  1989年   105606篇
  1988年   96567篇
  1987年   94588篇
  1986年   88804篇
  1985年   84782篇
  1984年   63208篇
  1983年   53638篇
  1982年   31460篇
  1981年   28041篇
  1979年   55913篇
  1978年   39253篇
  1977年   33404篇
  1976年   31146篇
  1975年   32962篇
  1974年   39316篇
  1973年   37583篇
  1972年   35097篇
  1971年   32576篇
  1970年   30101篇
  1969年   28768篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: Gastric cancer (GC) is the leading cause of cancer deaths in China. Our study prospectively evaluated the impact of repeated endoscopic screens on GC mortality in a high-risk population in China. METHODS: Between 1989 and 1999, a population-based gastroscopic screening was conducted in 4,394 residents of Linqu County, China, a region with the highest rates of GC worldwide. Residents ages 35 to 64 years received initial gastroscopies with biopsies in 1989. Repeated endoscopies were performed in 1994 and 1999. Cancer occurrences and deaths were actively monitored throughout the entire period until July 2000. Mortality from GC was compared with expected values based on mortality rates obtained for Linqu in the 1990-1992 Chinese Cancer Mortality Survey. RESULTS: Between March 1989 and July 2000, 39,303 person-years were accumulated; 85 new GCs occurred, 29 (34.5%) were in early stage. Fifty-eight cases (68%) were identified at one of the screens. The number of observed deaths from GC (37) was close to the expected (36.8). The standardized mortality ratio was 1.01 (95% CI 0.72-1.37) for the entire cohort, 1.13 (95% CI 0.77-1.57) for males, and 0.65 (95% CI 0.26-1.32) for females. CONCLUSIONS: Despite high population coverage with repeated screens, no reduction in GC mortality was observed in this high-risk population in China.  相似文献   
992.
Molecular chaperones assist in the biosynthesis and processing of proteins. Most chaperones are induced by physiological stresses. We have shown that dietary energy restriction decreases the mRNA and protein levels of many endoplasmic reticulum chaperones in the livers of mice. Here, we have investigated the response of chaperone mRNA to feeding. Control and 50% energy-restricted C3B10RF1 mice were deprived of food for 24 h, fed, and killed 0, 1.5, 5 or 12 h after feeding. Chaperone mRNAs were strongly induced as early as 1.5 h after feeding in control and energy-restricted mice. The integrated levels of these mRNA over 24 h were significantly lower in energy-restricted mice. The mRNA response to energy intake was mirrored over the course of days in the level of chaperone protein. A similar but smaller response to feeding was found in kidney and muscle. Puromycin and cycloheximide failed to inhibit the feeding response, suggesting that feeding releases chaperone expression from an unstable inhibitor. Studies with dibutyryl-cAMP- and glucagon-supplemented, normal and streptozotocin-diabetic mice suggest that glucagon and insulin may be mediators of the feeding response. Adrenalectomy enhanced the feeding induction, but dexamethasone administration had no effect. Thus, postprandial changes in insulin and glucagon may link chaperone gene expression to feeding, possibly in several tissues including liver.  相似文献   
993.
In this article, the authors review the cellular mechanisms of epileptogenicity in malformations caused by abnormalities of cortical development as related to neuronal excitation, reduced inhibition, disorganized synaptic connections, and glial function (or dysfunction).  相似文献   
994.
995.
996.
Zusammenfassung Anhand von 678 bis Ende 1979 operierten Patienten mit Lungenerkrankungen wird die technische Anwendung automatischer Nahtgeräte demonstriert. Sie eignen sich zum Bronehusverschluß, für Keilexcisionen sowie zum Verschluß von Lungenvenen. Technische Modalitäten sind zu beachten. Der Vorteil liegt bei sachgemäßem Vorgehen in der Sicherheit der Anwendung, der Effektivität und in der kürzeren Operationszeit. Die Insuffizienzquote beträgt einschl. der Anfangszeit 4,4% in der Spätphase 3,2%. Komplikationen bei Keilexcisionen treten ebensowenig auf wie beim Verschluß der Lungenvenen.  相似文献   
997.
Three cases of enteritis necroticans seen at Port Moresby General Hospital are described. All three cases proved diagnostic problems and in all three the diagnosis was made only at laparotomy. While the condition is uncommon in Port Moresby, these cases indicate that it must now be considered earlier rather than later.  相似文献   
998.
999.
1000.
A rare case of an advanced primary broad ligament carcinoma is discussed, with a review of the literature regarding its incidence, presentation and management. This patient showed a complete response to adjuvant cisplatin-based chemotherapy following panhysterectomy and is presently without any evidence of disease, 15 months after completion of her treatment.  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