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   8147篇
  免费   702篇
  国内免费   29篇
耳鼻咽喉   53篇
儿科学   196篇
妇产科学   212篇
基础医学   1204篇
口腔科学   115篇
临床医学   1037篇
内科学   1667篇
皮肤病学   95篇
神经病学   625篇
特种医学   478篇
外科学   1040篇
综合类   237篇
一般理论   2篇
预防医学   890篇
眼科学   51篇
药学   584篇
中国医学   7篇
肿瘤学   385篇
  2021年   103篇
  2020年   81篇
  2019年   109篇
  2018年   129篇
  2017年   118篇
  2016年   106篇
  2015年   159篇
  2014年   178篇
  2013年   265篇
  2012年   385篇
  2011年   427篇
  2010年   230篇
  2009年   199篇
  2008年   366篇
  2007年   311篇
  2006年   320篇
  2005年   305篇
  2004年   335篇
  2003年   319篇
  2002年   283篇
  2001年   305篇
  2000年   281篇
  1999年   263篇
  1998年   114篇
  1997年   127篇
  1996年   117篇
  1995年   112篇
  1994年   97篇
  1993年   84篇
  1992年   209篇
  1991年   204篇
  1990年   217篇
  1989年   181篇
  1988年   160篇
  1987年   145篇
  1986年   153篇
  1985年   138篇
  1984年   121篇
  1983年   93篇
  1982年   70篇
  1981年   56篇
  1979年   81篇
  1978年   62篇
  1977年   52篇
  1976年   48篇
  1974年   68篇
  1973年   47篇
  1972年   47篇
  1971年   45篇
  1970年   53篇
排序方式: 共有8878条查询结果,搜索用时 15 毫秒
91.
92.
The "Quit. For Life" campaign was a media-based programme that was aimed at reducing the prevalence of smoking in Sydney. The programme committee set four intermediate goals which it felt had to be met for such a change in prevalence to occur. From households selected at random in Sydney and Melbourne, 5713 people were interviewed to assess whether the campaign attained these goals. The television commercials that were designed for the campaign, their frequency and the timing of their screening produced a higher recall of the commercial's message and the use of campaign back-up services than were specified originally in the goals. During the campaign there was a progressive increase in the number of smokers in Sydney who reported that they were likely to quit; this was significantly different from Melbourne data by the end of the campaign and thus fulfilled another campaign goal. However, shortly after the campaign ended, the proportion of smokers who intended to quit smoking was the same in the two cities. A cohort study of 949 people from the baseline study showed that, during the 12-month period of follow-up, 66% of Sydney smokers tried to stop or to reduce their smoking. In the control city, Melbourne, 60% of smokers reported making such attempts. Of the original smokers, 23% in Sydney and 9% in Melbourne quit during the follow-up period--a statistically significant difference. As well, 10% of the original ex-smokers in Sydney and 11% in Melbourne relapsed, while 4% of nonsmokers in both cities began smoking by the end of the second survey.  相似文献   
93.
To test the hypothesis that physician education is an effective strategy to reduce total hospital costs, we evaluated three educational interventions at a large university hospital. This prospective controlled study spanned two academic years and involved 1,663 patients and 226 house staff. In the first year, weekly lectures on cost containment (medicine and surgery) and audit with feedback (medicine only) both failed to produce a significant change in total hospital charges. The "dose" of the intervention was increased on medicine in the second year by combining the lecture and audit strategies. Again, total charges did not change significantly. While decreased use occurred for certain selected services, the impact was not great enough to affect total hospital charges significantly. We conclude that, in the absence of other cost containing incentives, physician education alone is not an effective hospital cost containment strategy.  相似文献   
94.
A number of substituted phthalimide, 1, 8-naphthalimide, succinimide and glutarimide derivatives demonstrated significant hypolipidemic activity at 20 mg/kg/ day, I.P. after 16 days dosing. The N-(n-pentyl) succinimide proved to be the most potent analogue of the new compounds, lowering serum triglyceride levels 51 % and serum cholesterol 47 % after 16 days dosing in mice. For the N-substituted derivatives, i. e., n-butyl, butanone, and propionic acid, of these four cyclic imides, there appeared to be no obvious trend in ability to reduce serum lipid levels. In general, the 1,8-naphthalimide and glutarimide derivatives appeared to be less active than phthalimide and succinimide. However, the -phenylsuccinimide afforded less activity than the -phenylglutarimide. Most of the derivatives at 20mg/kg/day demonstrated improved activity over clofibrate at 150mg/kg/day.  相似文献   
95.
Protein supplements are increasingly used by older people to maintain nutrition and prevent or treat loss of muscle function. Daily protein requirements in older people are in the range of 1.2 gm/kg/day or higher. Many older adults do not consume this much protein and are likely to benefit from higher consumption. Protein supplements are probably best taken twice daily, if possible soon after exercise, in doses that achieve protein intakes of 30 gm or more per episode. It is probably not important to give these supplements between meals, as we have shown no suppressive effects of 30 gm whey drinks, and little if any suppression of 70 gm given to older subjects at varying time intervals from meals. Many gastrointestinal mechanisms controlling food intake change with age, but their contributions to changes in responses to protein are not yet well understood. There may be benefits in giving the supplement with rather than between meals, to achieve protein intakes above the effective anabolic threshold with lower supplement doses, and have favourable effects on food-induced blood glucose increases in older people with, or at risk of developing, type 2 diabetes mellitus; combined protein and glucose drinks lower blood glucose compared with glucose alone in older people.  相似文献   
96.
97.
98.
Comparable degrees of skin reactivity were observed towards spore and mycelium extracts from two isolates of Epicoccum and to one preparation of Alternaria in 35 rural and 120 university patients. The best experimental extracts detected Epicoccum sensitivity in 70% of the group tested while the commercial extract detected sensitivity in only 6%. Skin reaction correlations were greatest within isolates (eg, spore-A/mycelium-A), then for specific fungus parts (eg, spore-A/spore-B), then between isolates and parts (spore-A/mycelium-B). High correlations were found between individual IgG and IgE ELISA values for all antigens using serum from Epicoccum skin-reactive patients. ELISA inhibition results suggested that significant cross-reactivity exists between Epicoccum and Alternaria antigens recognized by IgG but not by IgE. ELISA inhibition cross-reaction patterns among Epicoccum antigens were comparable to skin reactions while IgG patterns showed little variability. Further characterization of spore/mycelium and interstrain recognition patterns among different immunoglobulin isotypes will be necessary before complete standardization of extracts from different parts of fungi will be possible. The use of spore material for skin testing and treatment of Epicoccum sensitivity appears to be both premature and unnecessary at this time.  相似文献   
99.
We have previously shown that sera from patients with Alzheimer’s disease (AD) contain antibodies to the cell bodies (perikarya; PK) of purely cholinergicTorpedo neurons, and that repeated immunization of rats with this neuronal preparation for over a year induces learning and memory impairments. In the present study, we examined the brain morphology of cholinergic PK immunized rats relative to controls. Immunohistochemical studies of the brains of these rats revealed the accumulation of IgG in specific areas, such as, the hippocampus. Parallel histochemical studies demonstrated significant changes in the hippocampus, and in white matter areas. They included large vacuoles and necrotic nuclei in the granular layer of the dentate gyrus, tangle-like appearance in some pyramidal neurons of the hippocampus, and vacuolar degeneration accompanied by oligodendroglia hypertrophy in white matter tracts, such as, the corpus callosum and fimbria. In contrast, immunization withTorpedo cholinergic nerve terminals, that has no cognitive effects on the rat, also did not induce brain morphological changes. These findings suggest that the learning and memory deficits induced by immunizing rats with cholinergic PK are related to the observed brain morphological changes, and support the hypothesis that the antibodies to cholinergic neurons found in the sera of AD patients may play a role in neuronal degeneration in this disease.  相似文献   
100.
Health care leadership has never been more difficult than in the past decade--and the next ten years promise to be even more demanding. As a new era for health care emerges, organizational leaders will be required to manage increased levels of risk, uncertainty, and rapid change. Successful chief executives will be those who recognize and nurture intangible leadership qualities including knowledge of self, commitment to service, and depth and breadth of vision. With the continued shift away from hospital inpatient care, health care leaders will be called on to develop multipurpose delivery systems that move from a market-based to a community-based focus and deliver high quality services in a cost-effective manner. Several leadership themes will unfold in the midst of health care reform, including: exploiting change for the good of the organization and community; serving as educator, communicator, and comforter to divergent constituencies; and reestablishing a balance between short-term goals and long-term vision.  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