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   2600828篇
  免费   189987篇
  国内免费   7675篇
耳鼻咽喉   34463篇
儿科学   85463篇
妇产科学   71814篇
基础医学   365969篇
口腔科学   70173篇
临床医学   235701篇
内科学   519977篇
皮肤病学   62748篇
神经病学   214464篇
特种医学   100438篇
外国民族医学   736篇
外科学   389315篇
综合类   50470篇
现状与发展   5篇
一般理论   969篇
预防医学   196715篇
眼科学   57112篇
药学   189097篇
  8篇
中国医学   5386篇
肿瘤学   147467篇
  2021年   20354篇
  2019年   20899篇
  2018年   29657篇
  2017年   22887篇
  2016年   26591篇
  2015年   29860篇
  2014年   40901篇
  2013年   60968篇
  2012年   81116篇
  2011年   85494篇
  2010年   51547篇
  2009年   49585篇
  2008年   79843篇
  2007年   84774篇
  2006年   86471篇
  2005年   82673篇
  2004年   79615篇
  2003年   76972篇
  2002年   74155篇
  2001年   128792篇
  2000年   131704篇
  1999年   110868篇
  1998年   31462篇
  1997年   28099篇
  1996年   28407篇
  1995年   27536篇
  1994年   25196篇
  1993年   23530篇
  1992年   85503篇
  1991年   81870篇
  1990年   79046篇
  1989年   76356篇
  1988年   69750篇
  1987年   68240篇
  1986年   63789篇
  1985年   60724篇
  1984年   45099篇
  1983年   38061篇
  1982年   22542篇
  1981年   20053篇
  1979年   39076篇
  1978年   27544篇
  1977年   23325篇
  1976年   21547篇
  1975年   22861篇
  1974年   26851篇
  1973年   25424篇
  1972年   23807篇
  1971年   22034篇
  1970年   20248篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
The present study explored the role of murine monocyte chemotactic protein (MCP) in the T cell-mediated hypersensitive granulomatous response to Schistosoma mansoni eggs. The study examined the time course of local production, contribution to cellular infiltration, and the role of T cells in endogenous regulation. Synchronized pulmonary granulomas were induced under conditions of primary and secondary states of immunity. Primer-directed polymerase chain reaction analysis showed increased MCP mRNA expression in granulomatous lungs, mainly in the secondary response. Levels of MCP were measured by enzyme-linked immunosorbent assay in cultures of intact granulomas. Spontaneous MCP production was modest in primary granuloma cultures, reaching a maximum of 5.7 +/- 0.9 ng/ml by 16 days. In contrast, the secondary response showed augmented and accelerated production, achieving 13 +/- 2.0 ng/ml by 2 days. Immunohistochemical staining revealed the strongest MCP expression within microvascular adventitial cells or pericytes as well as in scattered mononuclear cells associated with granulomas. Staining was not detected in normal lungs. Passive immunization with anti-MCP-1 antibodies caused a 40% reduction in the secondary granuloma area but did not significantly affect the primary response. With adoptive cell transfer and T cell subset depletion, it was shown that Thy-1+ and CD5+ cells augmented, whereas CD8+ cells appeared to impair, MCP production. This provides direct evidence that MCP is involved in secondary Th2-mediated response to schistosome eggs and is subject to regulation by T cells.  相似文献   
942.
943.
944.
Mycobacteriosis due to Mycobacterium genavense in six pet birds.   总被引:11,自引:7,他引:4       下载免费PDF全文
Six cases of mycobacteriosis due to Mycobacterium genavense in three budgerigars (Melopsittacus undulatus), one orange-winged amazon (Amazona amazonica), one flycatcher (Cyanoptila cyanomelana), and one zebra finch (Taeniopygia guttata) are discussed. Gross lesions associated with the infection included a high degree of muscular wasting (five cases), hepatomegaly (four cases), and thickening of the wall of the small intestine (four cases). Granulomas were found in the lung (one case) and the subcutis (one case). Acid-fast bacilli were detected in the liver of all six birds. Only the use of acidic BACTEC mediums consistently led to growth, whereas the egg-based medium failed. These findings point to a possible role of the environment as a reservoir for M. genavense.  相似文献   
945.
The decoction of Sclerocarya birroea Hochst. shows hypoglycaemic effects, an increase in plasma IRI in normal rats and an incremented oral-glucose tolerance. The decoction is also active against diet-induced hypercholesterolaemia.  相似文献   
946.
Owing to large differences in the incidence of AIDS (acquired immunodeficiency syndrome) and in public health resources and priorities, the impact of AIDS on state and local health departments has been variable. Nonetheless, health departments everywhere are being held responsible for surveillance and control of the HIV (human immunodeficiency virus) epidemic which we believe requires, at minimum, convenient, free HIV testing and counseling; expanded HIV services in sexually transmitted diseases clinics and substance treatment centers; locally oriented AIDS information/education; notification of persons unknowingly exposed to HIV; restrictive measures for HIV-infected persons who, after counseling, persist in exposing others; regulation or closure of public establishments in which HIV transmission is likely to result; and confidential reporting of all HIV test results to public health departments. In Colorado new legislation was passed to require reporting of HIV test results, to provide the reports with near absolute protections against unauthorized disclosure, and to modify quarantine statues to incorporate rights to due process, appeals, and confidentially. States in which there is a legal basis for discrimination against gay men will need to rectify this problem first. There is no evidence that reporting of HIV infections in Colorado has adversely affected the rate at which persons with HIV risk behaviors volunteer to be tested. For Denver and Colorado Departments of Health, more than 70 per cent of the estimated $2,796,000 expended in AIDS activities during 1987 was federal.  相似文献   
947.
948.
949.
950.
An analysis of mortality data for the years 1982-5 was carried out for the Micronesian population (aged 15 years and over) of the central Pacific Island, Nauru. Among males, the most common causes of death were circulatory system disorders (33.3%), accidents (25.2%), and diabetes mellitus (12.1%). The majority of accidents occurred in the 15-34 year age group and involved motor vehicles. Among females, neoplasms (almost all lung and cervix) (22.4%), circulatory system disorders (20.7%), and diabetes mellitus (17.2%) were the most common causes of death. When accidents are excluded, 59.4% of deaths were in persons with diabetes. Compared with Australia, mortality rates in almost all age groups were at least five times higher for males and females for a comparable period. Nauruan life expectancy (39.5 years for men and 48.5 years for women) is one of the lowest in the world. These data confirm the high mortality associated with diabetes mellitus in Nauruans as evidenced in earlier studies. Modernization of this society through the affluence acquired by the mining of phosphate has led to serious public health problems relating to non-communicable diseases so that the mortality trends now mirror those of developed societies.  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