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   2981篇
  免费   275篇
  国内免费   42篇
耳鼻咽喉   13篇
儿科学   96篇
妇产科学   54篇
基础医学   267篇
口腔科学   74篇
临床医学   424篇
内科学   745篇
皮肤病学   47篇
神经病学   242篇
特种医学   219篇
外国民族医学   1篇
外科学   363篇
综合类   102篇
预防医学   228篇
眼科学   78篇
药学   176篇
中国医学   1篇
肿瘤学   168篇
  2021年   38篇
  2020年   19篇
  2019年   34篇
  2018年   46篇
  2017年   28篇
  2016年   25篇
  2015年   50篇
  2014年   69篇
  2013年   111篇
  2012年   102篇
  2011年   120篇
  2010年   81篇
  2009年   109篇
  2008年   128篇
  2007年   140篇
  2006年   118篇
  2005年   123篇
  2004年   92篇
  2003年   70篇
  2002年   97篇
  2001年   91篇
  2000年   90篇
  1999年   72篇
  1998年   62篇
  1997年   74篇
  1996年   65篇
  1995年   62篇
  1994年   61篇
  1993年   46篇
  1992年   68篇
  1991年   78篇
  1990年   82篇
  1989年   87篇
  1988年   72篇
  1987年   60篇
  1986年   61篇
  1985年   54篇
  1984年   34篇
  1983年   48篇
  1982年   28篇
  1981年   26篇
  1980年   24篇
  1979年   33篇
  1978年   35篇
  1977年   21篇
  1976年   22篇
  1974年   28篇
  1973年   26篇
  1972年   19篇
  1969年   19篇
排序方式: 共有3298条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
AIM: Ultraviolet light (UV) is known to cause DNA damage in the epidermis. The damaged DNA is repaired or deleted by apoptosis to prevent the generation of cancer. It has been suggested that a deficient apoptotic mechanism may predispose individuals to skin cancer. Therefore, the response of normal controls and patients with basal cell carcinoma (BCC) to UV irradiation was investigated. METHODS: The buttock skin from normal volunteers and patients with BCC was irradiated using solar simulated radiation (SSR). SSR mimics the effect of natural sunlight. Skin biopsies were excised and examined for p53, p21, and Bax protein expression and for the induction of apoptosis. RESULTS: At 33 hours after UV irradiation, the induction of apoptosis was significantly higher (p = 0.04) in patients with BCC than in normal volunteers (Mann Whitney test). A trend towards higher p21 expression was found at 33 hours in patients with BCC (mean, 18.69 positive cells/field) than in normal volunteers (mean, 9.89), although this difference was not significant (p = 0.05 positive cells/field). CONCLUSION: These results may imply that patients with BCC have enhanced sensitivity to UV irradiation or that there is some defect in the cell arrest or repair pathways, which results in damaged cells been pushed into apoptosis rather than repair.  相似文献   
35.
This study provides the first psychophysiological analysis of narcissism by measuring autonomic responses during active and passive anticipatory coping in 40 undergraduate men who scored high or low on the Narcissistic Personality Inventory (NPI). Compared to the low NPI group, the high NPI group showed greater preejection period (PEP) shortening, cardiac deceleration, and skin conductance response (SCR) habituation during anticipation of an aversive stimulus (p < .02). As expected, SCR and PEP reactivity were greater during active than passive coping. In the case of PEP, this effect emerged only in the low NPI group; the high NPI group showed the greatest PEP reactivity during the first task, regardless of coping demands. These data support hypothesized relationships among narcissism, psychopathy, and psychological predictors of cardiovascular disease, and suggest that a psychobiological dimension may underlie important features of narcissism.  相似文献   
36.
37.
38.
Cognitive Impairment (CI) screening is recommended for those engaged in harmful levels of alcohol use. However, there is a lack of evidence on implementation. This paper explores the barriers and facilitators to CI screening experienced across a service specifically for older drinkers. The findings draw on data gathered as part of an evaluation of a multilevel programme to reduce alcohol-related harm in adults aged 50 and over in five demonstration areas across the United Kingdom. It is based on qualitative interviews and focus groups with 14 service providers and 22 service users. Findings are presented thematically under the section headings: acceptability of screening, interpretation and making sense of screening and treatment options. It is suggested that engagement with CI screening is most likely when its fit with agency culture and its purpose is clear; where service providers have the technical skills to administer and discuss the results of screening with service users; and where those undertaking screening have had the opportunity to reflect on their own experience of being screened. Engagement with CI screening is also most likely where specific intervention pathways and engagement practices can be accessed to respond to assessed need.  相似文献   
39.
SUMMARY  Modafinil is an alerting substance that is considered safer than amphetamine with fewer side effects. Although modafinil has been used successfully to treat narcolepsy, relatively little is known about its ability to ameliorate fatigue and declines in mental performance due to sleep deprivation (SD) in a normal population. Forty-one military subjects received either 300 mg of modafinil, 20 mg of d-amphetamine, or placebo on 3 separate occasions during 64 hours of continuous cognitive work and sleep loss. Three drug treatments were given: at 23.30 hours and 05.30 hours during the first and second SD nights, respectively, and once at 15.30 hours during the third day of continuous work. Subjective estimates of mood, fatigue and sleepiness, as well as objective measures of reaction time, logical reasoning and short-term memory clearly showed better performance with both modafinil and amphetamine relative to placebo. Both modafinil and amphetamine maintained or increased body temperature compared to the natural circadian cycle observed in the placebo group. Also, from subject debriefs at the end of the study, modafinil elicited fewer side-effects than amphetamine, although more than the placebo group. Modafinil appears to be a good alternative to amphetamine for counteracting the debilitating mood and cognitive effects of sleep loss during sustained operations.  相似文献   
40.
To decrease respiratory infections in senior day care, staff were educated on viral transmission and the value of hand washing. Fanny packs with alcohol foam supplemented hand washing and were alternated monthly between centers. Infection rates were unchanged with alcohol foam use. The intervention year's infection rate was significantly lower than the previous 3 years, suggesting a benefit of education.  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