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   4750篇
  免费   370篇
  国内免费   6篇
耳鼻咽喉   31篇
儿科学   279篇
妇产科学   129篇
基础医学   612篇
口腔科学   66篇
临床医学   603篇
内科学   993篇
皮肤病学   52篇
神经病学   407篇
特种医学   91篇
外科学   490篇
综合类   90篇
一般理论   3篇
预防医学   668篇
眼科学   58篇
药学   326篇
中国医学   4篇
肿瘤学   224篇
  2023年   57篇
  2022年   41篇
  2021年   102篇
  2020年   84篇
  2019年   125篇
  2018年   131篇
  2017年   99篇
  2016年   90篇
  2015年   98篇
  2014年   126篇
  2013年   185篇
  2012年   299篇
  2011年   298篇
  2010年   166篇
  2009年   129篇
  2008年   249篇
  2007年   213篇
  2006年   199篇
  2005年   252篇
  2004年   243篇
  2003年   195篇
  2002年   182篇
  2001年   88篇
  2000年   95篇
  1999年   96篇
  1998年   49篇
  1997年   31篇
  1996年   35篇
  1995年   38篇
  1994年   40篇
  1993年   25篇
  1992年   58篇
  1991年   74篇
  1990年   64篇
  1989年   64篇
  1988年   86篇
  1987年   65篇
  1986年   48篇
  1985年   65篇
  1984年   52篇
  1983年   63篇
  1982年   32篇
  1981年   36篇
  1980年   25篇
  1979年   27篇
  1978年   23篇
  1974年   27篇
  1973年   24篇
  1972年   26篇
  1969年   19篇
排序方式: 共有5126条查询结果,搜索用时 15 毫秒
11.
A preliminary study measured the contrast sensitivity function (CSF) in 30 children (aged 3 months-5 years). Preferential looking techniques were used to assess CSF to sine wave gratings displayed on one of two screens. To find a meaningful contrast sensitivity procedure we compared the results with a shorter procedure using an edge stimulus. The following problems were encountered: measuring the contrasts required to detect four or five different spatial frequencies took time, resulting in boredom and loss of attention in our subjects; there was poor correlation between CSF and edge detection; an interesting artefact resulted in a plateau rather than a low frequency fall-off in the CSF of five of the children greater than 30 months old. This artefact may have resulted from peripheral rather than central retinal responses and/or motion artefacts in the stimulus onset. A follow up study with 41 additional children aged 3-36 months limited the contrast testing to that of the spatial frequency corresponding to the peak of the CSF. The shortened procedure, plus a lot of encouragement, resulted in higher contrast sensitivities in all but the oldest age group and successful monocular contrast measurements. In order to avoid artefacts arising from peripheral vision, children were encouraged to look at each screen before responding.  相似文献   
12.
13.
This study used magnetic resonance imaging to examine pituitary gland volume (PGV) in teenage patients with a first presentation of borderline personality disorder (BPD). No difference in PGV was observed between healthy controls (n = 20) and the total BPD cohort (n = 20). However, within the BPD cohort, those exposed to childhood trauma (n = 9) tended to have smaller pituitaries (− 18%) than those with no history of childhood trauma (n = 10). These preliminary findings suggest that exposure to childhood trauma, rather than BPD, per se, might be associated with reduced PGV, possibly reflecting hypothalamic–pituitary–adrenal axis dysfunction.  相似文献   
14.
This article celebrates the continuing differences between men and women that are present in our twilight years. Although men die earlier than women, they spend fewer years with major disability. There is increasing interest in the use of testosterone to improve the quality of life in both older men and women. Sarcopenia, osteopenia, hip fractures, and frailty are all more common in women than in men. Sexuality remains important to both men and women throughout life. Finally, it is known that cytokines play a major role in the pathophysiology of aging, a process now recognized as the cytokine-related aging process.  相似文献   
15.
Are there any successful men from criminogenic backgrounds?   总被引:4,自引:0,他引:4  
In the Cambridge Study in Delinquent Development, a prospective longitudinal survey of 411 London males, a vulnerable group of 63 boys from criminogenic backgrounds was defined on the basis of the best nonbehavioral predictors of delinquency at age 8-10 (low family income, large family size, convicted parents, low intelligence, and poor parental child-rearing behavior). These males were followed up to age 32, and the more successful men were defined according to criteria such as the absence of convictions and of other deviant behavior, good relationships with wives and children, and good accommodation and employment histories. Hence, "success" here refers to satisfactory social adjustment. The more successful men were those who had been neurotic at age 10, those who had few or no friends at age 8, those without convicted parents or behavior problem siblings, those with mothers who had a high opinion of their sons, and those who did not spend their leisure time with their fathers. At age 8-10 they were already better behaved and less daring than those later judged as the unsuccessful men. There was some tendency for shyness to act as a protective factor against delinquency for non-aggressive boys but as an aggravating factor for aggressive boys.  相似文献   
16.
It has been shown that spreading depression of the hippocampus can elicit feeding, and that several opioid peptides elicit spreading depression when injected into the hippocampus. To determine whether such depression is the primary mechanism by which opiates induce feeding, we tested the feeding effects of naloxone, an opiate antagonist, and butorphanol tartrate, a kappa-sigma agonist, on feeding in rats with and without hippocampal lesions. Naloxone tended to reduce intake approximately equally in the two groups. Similarly, the doses of butorphanol that increased intake in sham rats were equally effective in lesioned rats. It was concluded that the hippocampus is not the major structure mediating opiate-induced feeding.  相似文献   
17.
BACKGROUND: Depression is the most common mental health disorder in people aged over 65 years. Late-life depression is associated with chronic illness and disability. AIM: To investigate the feasibility of a collaborative care model for depression in older people in a primary care setting. DESIGN OF STUDY: Randomised controlled trial with 16-weeks follow up. SETTING: A primary care trust in Manchester. METHOD: Participants were 105 people aged 60 years or older who scored 5 or more on the Geriatric Depression Scale; 53 were randomly allocated to an intervention group and 52 to a usual care group. The intervention group received care managed by a community psychiatric nurse who delivered an intervention comprising a facilitated self-help programme with close liaison with primary care professionals and old-age psychiatry according to a defined protocol. The usual care group received usual GP care. A nested qualitative study explored the views of the health professionals and patients regarding the acceptability and effectiveness of the intervention. RESULTS: The main outcome measure was recovery from depression. Patients in the intervention group were less likely to suffer from major depressive disorder at follow up compared with usual care (0.32, 95% confidence = interval = 0.11 to 0.93, P = 0.036). The qualitative component of the study demonstrated the acceptability of the intervention to patients. CONCLUSION: A model of collaborative care for older people with depression, used in a primary care setting with a facilitated self-help intervention is more effective than usual GP care. This study demonstrates that the implementation of a collaborative care model is feasible in UK primary care and that the intervention is effective and acceptable to patients.  相似文献   
18.
Guinea-pigs were immunized with an emulsion of human thyroglobulin (Tg) and BCG vaccine in Freund's incomplete adjuvant. Peripheral blood lymphocytes binding Tg and purified protein derivative of mammalian tuberculin (PPD) labelled with 125I were demonstrated with an autoradiographic technique. The percentage of these cells was compared with the size of the delayed hypersensitivity (DH) skin reactions to Tg and PPD, and Tg antibody titres at intervals up to 35 days after immunization. The individual responses to Tg showed the time course of primary immune reactions although they did not parallel each other closely. By contrast, a depression of cutaneous DH to PPD was observed in spite of the presence of substantial numbers of 125I-PPD-binding peripheral blood lymphocytes. In non-immune guinea-pigs, approximately 2·8% of peripheral blood lymphocytes bound 125I-PPD whereas <0·1% bound 125I-Tg.

The significance of antigen-binding lymphocytes in the immune response is discussed, and it is suggested that the presence of a substantial pool of antigen-binding lymphocytes in unprimed may be of importance in the induction of DH.

  相似文献   
19.
20.
Screening for cognitive impairment in older African-Caribbeans   总被引:1,自引:0,他引:1  
BACKGROUND: There are increasing numbers of older African-Caribbeans in the United Kingdom. Screening instruments are commonly used in the detection of cognitive impairment, but have not been assessed within this population. This study aimed to develop culturally modified versions of screening instruments for cognitive impairment (Mini-Mental State Examination (MMSE) and Abbreviated Mental Test (AMT)) and to determine their sensitivity and specificity in the diagnosis of dementia. METHODS: The instruments were modified using a process involving a community group of African-Caribbeans and an academic group of health professionals. They were used in a two-stage study involving community resident African-Caribbeans aged 60 years or over in inner-city Manchester, comparing the screening instruments against a computerized diagnostic interview. RESULTS: One hundred and thirty people completed the study. The results for the largest subgroup, the Jamaicans (N = 96) were analysed. Effects of gender, age and education on the MMSE and AMT scores were evaluated. The correlations between the screening instruments and diagnostic interview were highly significant (P < 0.001). At appropriate cut-offs both screening instruments demonstrated high sensitivity and acceptable specificity levels. CONCLUSIONS: A defined process with lay input has assisted in producing culturally modified versions of the MMSE and AMT that perform well compared with a diagnostic interview, if an appropriate cut-off is used. They are easy to administer and acceptable to older African-Caribbean people. The results need to be viewed within the limitations of the current study.  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