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   321213篇
  免费   18580篇
  国内免费   469篇
耳鼻咽喉   4601篇
儿科学   11327篇
妇产科学   11086篇
基础医学   49018篇
口腔科学   8065篇
临床医学   26214篇
内科学   60804篇
皮肤病学   6818篇
神经病学   23452篇
特种医学   12634篇
外国民族医学   57篇
外科学   50214篇
综合类   7880篇
现状与发展   1篇
一般理论   163篇
预防医学   21222篇
眼科学   7429篇
药学   22195篇
中国医学   806篇
肿瘤学   16276篇
  2021年   2562篇
  2019年   2562篇
  2018年   4011篇
  2017年   2990篇
  2016年   3542篇
  2015年   3937篇
  2014年   5186篇
  2013年   7991篇
  2012年   10197篇
  2011年   10649篇
  2010年   6727篇
  2009年   6195篇
  2008年   9777篇
  2007年   10703篇
  2006年   10464篇
  2005年   10087篇
  2004年   9606篇
  2003年   9114篇
  2002年   8636篇
  2001年   14176篇
  2000年   14506篇
  1999年   12152篇
  1998年   3358篇
  1997年   3045篇
  1996年   2847篇
  1995年   2739篇
  1994年   2517篇
  1992年   8761篇
  1991年   8911篇
  1990年   8719篇
  1989年   8455篇
  1988年   7666篇
  1987年   7452篇
  1986年   7078篇
  1985年   6876篇
  1984年   5018篇
  1983年   4317篇
  1982年   2609篇
  1979年   4670篇
  1978年   3408篇
  1977年   2881篇
  1976年   2649篇
  1975年   2994篇
  1974年   3533篇
  1973年   3523篇
  1972年   3269篇
  1971年   3073篇
  1970年   2961篇
  1969年   2688篇
  1968年   2633篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
The acting or interim leadership position has been neglected in terms of selection, role identification, and status. Individuals, programs, and organizations are paying a price for this inattention.  相似文献   
63.
64.
Recently, we demonstrated that spaghetti caused significantly lower glycaemic response than rice and potato in insulin-dependent diabetic (IDDM) subjects and that this difference was also present when spaghetti and potato were taken as part of a mixed meal. We have now compared the blood glucose and insulin responses to 50 g of carbohydrate in the form of white bread, potato and white spaghetti in 6 non-insulin-dependent diabetic (NIDDM) patients. The blood glucose response after white spaghetti observed over a 3-h period was only 60 +/- 10 per cent (P less than 0.02) of that seen in response to potato (395 +/- 116 mmol/l x 180 min vs 641 +/- 108 mmol/l x 180 min) and 47 +/- 9 per cent (P less than 0.01) of that seen in response to white bread (395 +/- 116 mmol/l x 180 min vs 805 +/- 93 mmol/l x 180 min). Insulin responses showed an identical pattern reflecting the glycaemic responses. To see if the difference in the glucose responses in NIDDM patients is preserved if these carbohydrate-rich foods are taken as part of a mixed meal we looked at the blood glucose and insulin responses to 50 g of carbohydrate in the form of potato and white spaghetti when ingested together with bolognese sauce (167 g) in 7 NIDDM patients.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
65.
The in vitro activities of povidone iodine, potassium peroxymonosulfate, and dimethyldidecylammonium chloride were investigated against 379 nosocomial isolates of Staphylococcus aureus and Pseudomonas aeruginosa responsible for surgical wound infections in patients operated on between July 1995 and June 2001. Overall, the isolates were inhibited by the antiseptics at concentrations below those used routinely. In spite of increasing resistance to the various antibiotics used to treat surgical wound infections, no significant variation in the susceptibility to antiseptics was demonstrated during this 6-year study. Electronic Publication  相似文献   
66.
OBJECTIVE AND DESIGN: Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells. METHODS: We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production. RESULTS: We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced IL-8 production, which was abolished in the presence of the ERK activation inhibitor U0126. CONCLUSIONS: We conclude that PE activates the ERK1/2 arm of the MAPK pathway and that activation of this pathway results in enhanced IL-8 production. The results demonstrate that PE may augment pulmonary inflammation via cellular signaling that regulates expression of IL-8.  相似文献   
67.
68.
Formulae for the calculation of the count of microorganisms isolated from natural bacterial biocenoses of a child's body have been derived. The authors suggest a variant of simplified drip method for the computation of microorganism colonies in solid media. The described method helps cut down the nutrient media consumption at least 3-fold and is time-saving.  相似文献   
69.
The aqueous, organic, and volatile oil extracts of leaves of Eugenia uniflora Linn. Family Myrtaceae were investigated for antibacterial properties using agar dilution techniques. The aqueous extract was the most active against the organisms compared to the organic and volatile oil extracts. The extracts were found to inhibit Gram positive Staphylococcus aureus and Bacillus subtilis and Gram negative Escherichia coli and Shigella dysentcriae. Pseudomonas aeruginosa, Klebsiella pneumoniac, and Salmonella typhi were not inhibited.  相似文献   
70.
The effects of hemorrhagic shock (HE) on duodenal pH, acid-neutralizing capacity and mucosal tolerance to acid were investigated in anesthetized rats, and they were compared with those of indomethacin. HE was performed by bleeding from the carotid artery to reduce arterial blood pressure to about 55 mmHg (3 ml of bleeding per 200 g of body weight), and indomethacin was given s.c. in a dose of 5 mg/kg. Duodenal pH was determined in the outflow from the proximal duodenum (1.7 cm) which was perfused with 10(-4) M HCl, and acid-neutralizing capacity was measured by back-titration of the perfusate to pH 4.0 with 10 mM HCl. Under these conditions, duodenal pH was kept at around 6.0 as the result of neutralization in the loop (approximately 8 microEq/hr). Both HE and indomethacin significantly decreased the pH and acid-neutralizing capacity. Administration of 16,16-dimethyl prostaglandin E2 (16-dmPGE2: 30 micrograms/kg, s.c.) significantly increased both pH and acid-neutralizing capacity in normal and indomethacin-treated rats, but failed to affect these parameters in rats under HE conditions. When the duodenal loop was perfused with 50 mM HCl for 1.5 hr, both HE and indomethacin induced extensive damage in the mucosa. Pretreatment with 16-dmPGE2 significantly reduced the formation of duodenal lesions induced by indomethacin but not by HE. These results suggest that HE as well as indomethacin impaired duodenal acid-neutralizing capacity to reduce the tolerance to acid of the mucosa. The deleterious effects of HE on the mucosa may be mainly due to a decreased mucosal blood flow, but not due to a deficiency of endogenous prostaglandins.  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