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   619983篇
  免费   40767篇
  国内免费   2170篇
耳鼻咽喉   8339篇
儿科学   19538篇
妇产科学   17183篇
基础医学   100927篇
口腔科学   17806篇
临床医学   52523篇
内科学   113232篇
皮肤病学   14445篇
神经病学   43522篇
特种医学   22138篇
外国民族医学   67篇
外科学   92204篇
综合类   13581篇
一般理论   154篇
预防医学   46601篇
眼科学   14748篇
药学   49649篇
中国医学   1806篇
肿瘤学   34457篇
  2018年   6472篇
  2016年   5221篇
  2015年   5883篇
  2014年   7871篇
  2013年   11854篇
  2012年   16210篇
  2011年   17765篇
  2010年   10432篇
  2009年   9706篇
  2008年   16814篇
  2007年   18025篇
  2006年   18265篇
  2005年   17248篇
  2004年   16798篇
  2003年   15902篇
  2002年   15633篇
  2001年   30102篇
  2000年   31306篇
  1999年   25677篇
  1998年   7168篇
  1997年   5998篇
  1996年   5897篇
  1995年   5413篇
  1994年   5036篇
  1992年   19072篇
  1991年   19686篇
  1990年   19573篇
  1989年   18910篇
  1988年   17621篇
  1987年   17326篇
  1986年   16332篇
  1985年   15600篇
  1984年   11401篇
  1983年   9811篇
  1982年   5423篇
  1981年   4942篇
  1979年   11027篇
  1978年   7863篇
  1977年   6606篇
  1976年   6347篇
  1975年   7384篇
  1974年   8787篇
  1973年   8337篇
  1972年   8120篇
  1971年   7758篇
  1970年   7133篇
  1969年   6857篇
  1968年   6443篇
  1967年   5761篇
  1966年   5179篇
排序方式: 共有10000条查询结果,搜索用时 263 毫秒
991.
992.
Test meals with 10.9 g dietary fibre from sugar beet and corresponding control meals were given to eight healthy subjects, aged 67 ± 9 years. The postprandial glucose, triglyceride, hormone and glycerol responses were monitored during 3 hours. After the beet fibre meal the insulin and C-peptide areas were reduced by 28 ( P < 0.01) and 22% ( P > 0.025), respectively, and the somatostatin levels increased by approximately 30% ( P > 0.05). Further, the maximum relative postprandial reduction of plasma glycerol levels was less evident after the fibre-rich meal than after the control meal (36 ± 4% v. 46 ± 4%, P < 0.05). There was no apparent difference in the overall glycaemic response between the meals. The triglyceride levels were similar after both test meals.
Suspension of beet fibre bread given to rats by oro-gastric intubation induced lower blood glucose response than a control bread at 15 and 30 min ( P < 0.001), respectively, but a similar insulin response.
The results suggest an effect of beet fibre on the rate of carbohydrate absorption, expressed as a lower insulin response in the healthy volunteers and a reduced glucose response in the rat.
The mechanism behind this effect in healthy subjects could possibly be mediated by an increased somatostatin response.  相似文献   
993.
This report describes a young high-myopic patient who developed rubeosis iridis with peripheral retinal neovascularization one year after a circular buckling operation. Subsequently, vitreous bleeding and exudation led to traction retinal detachment which was treated successfully by anterior vitrectomy and cryopexy. It is suggested that this case represents a mild form of anterior-segment ischemia, combined with peripheral retinal ischemia.  相似文献   
994.
The urinary excretion of the n-hexane metabolite 2,5-hexanedione (HD) was determined in four shoe factory workers during four workingdays that were preceded by four free days and followed by two free days. The correlation between excretion of HD and the n-hexane concentrations in the workroom air was evaluated. The air concentrations of n-hexane and those of acetone, toluene, and other organic solvents were monitored with charcoal tubes. All the urine from each worker was collected at freely chosen intervals during the experimental period and the following two free days. The samples were analysed by gas chromatography. The relative excretion of HD increased as the exposure to n-hexane increased, although it seemed that HD accumulated progressively in the body at the highest n-hexane concentrations and at higher total solvent concentrations.  相似文献   
995.
996.
997.
A morphological examination of synovial tissue from 25 patients with rheumatoid arthritis revealed that binucleated or multinucleated plasma cells were present in all samples and absent in synovia obtained from 16 control patients. Plasma cells containing two, three of four nuclei constitutet a mean 3% of the total plasma cell population. They were aways found amongst plasma cell infiltrates and in close association with small blood vessels. Ultrastructural analysis found no evidence of cellular membranes separating the individual nuclei in binucleated or multinucleated plasma cells, suggesting that the cells did not arise from fusion. Some of these plasma cells had a diameter approaching 100 μm, and many were in intimate contact with macrophages. The demonstration of a few cells with mitotic figures within the infiltrates suggests that the maintenance of plasma cell numbers in rheumatoid synovium may depend, in part, upon their local proliferation. Received: 25 August 1997 / Accepted: 2 October 1997  相似文献   
998.
Cationic Lipid-Based Gene Delivery Systems: Pharmaceutical Perspectives   总被引:4,自引:0,他引:4  
Gene delivery systems are designed to control the location of administered therapeutic genes within a patient's body. Successful in vivo gene transfer may require (i) the condensation of plasmid and its protection from nuclease degradation, (ii) cellular interaction and internalization of condensed plasmid, (iii) escape of plasmid from endosomes (if endocytosis is involved), and (iv) plasmid entry into cell nuclei. Expression plasmids encoding a therapeutic protein can be, for instance, complexed with cationic liposomes or micelles in order to achieve effective in vivo gene transfer. A thorough knowledge of pharmaceutics and drug delivery, bio-engineering, as well as cell and molecular biology is required to design optimal systems for gene therapy. This mini-review provides a critical discussion on cationic lipid-based gene delivery systems and their possible uses as pharmaceuticals.  相似文献   
999.
A high incidence of bladder cancer has been documented in an area of chronic arsenic (As) exposure. This study investigates the characteristics of As-associated (n = 49) and other (n = 64) bladder cancers. A higher histological grading was observed for the As-exposed tumours (P = 0.04), but no other difference in pathobiological features or prognosis was found between the two groups.  相似文献   
1000.
A comparative clinical trial between two newly introduced intralesional treatments for acute leishmaniasis and the established treatment of intralesionally-administered pentavalent antimony compounds was performed. Treatments were allocated randomly to a total of 63 patients who received 2% zinc sulphate, 7% sodium chloride solutions or sodium stibogluconate intralesionally. A number of patients were left without treatment as controls. Patients were followed-up for 45 days, the results showing that the three treatments gave comparable cure rates by the end of the follow-up period. However, zinc sulphate gave a high cure rate (94.8%) usually with a single injection.  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