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   46227篇
  免费   4912篇
  国内免费   117篇
耳鼻咽喉   447篇
儿科学   1223篇
妇产科学   1100篇
基础医学   6951篇
口腔科学   1071篇
临床医学   5706篇
内科学   8494篇
皮肤病学   561篇
神经病学   4465篇
特种医学   1795篇
外国民族医学   57篇
外科学   5957篇
综合类   1000篇
一般理论   43篇
预防医学   5161篇
眼科学   1134篇
药学   3461篇
中国医学   24篇
肿瘤学   2606篇
  2021年   658篇
  2020年   414篇
  2019年   648篇
  2018年   720篇
  2017年   559篇
  2016年   608篇
  2015年   646篇
  2014年   973篇
  2013年   1540篇
  2012年   2039篇
  2011年   2077篇
  2010年   1249篇
  2009年   1093篇
  2008年   1980篇
  2007年   1972篇
  2006年   2008篇
  2005年   1929篇
  2004年   1951篇
  2003年   1718篇
  2002年   1698篇
  2001年   1488篇
  2000年   1615篇
  1999年   1366篇
  1998年   599篇
  1997年   527篇
  1996年   484篇
  1995年   483篇
  1994年   442篇
  1993年   409篇
  1992年   1073篇
  1991年   1112篇
  1990年   1022篇
  1989年   1011篇
  1988年   1009篇
  1987年   880篇
  1986年   869篇
  1985年   842篇
  1984年   700篇
  1983年   586篇
  1982年   385篇
  1981年   359篇
  1980年   349篇
  1979年   663篇
  1978年   518篇
  1977年   441篇
  1976年   415篇
  1975年   382篇
  1974年   438篇
  1973年   435篇
  1972年   377篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The degree of concordance of growth rates of primary tumors with corresponding recurrences was investigated by using data from 184 patients with breast cancer with measurable recurrences. For conduction of this examination, the detection processes of both the primary tumor and the recurrence were explored. The probability of detection of a recurrence per unit time was found to be nearly proportional to the tumor's diameter. Approximately 60,000 cells initiated the recurrence, and the distribution of doubling times of the recurrences was exponential, with a mean of 2.1 months. The probability of detection of the primary tumor per unit time was approximately proportional to its volume. The distribution of doubling times of primary tumors was nearly exponential; from other evidence, we inferred that the mean doubling time was also close to 2.1 months. Several techniques to measure growth rate agreement between the primary and recurrent tumors within individuals were developed, and all of them yielded the result that the growth rates are nearly unrelated.  相似文献   
102.
Intraocular pressure (IOP) was recorded regularly over a 24-h period in 13 normal subjects. All subjects showed a dramatic rise in IOP after sleep, ranging from 37 to 248%. In a second experiment, IOP decreased when 15 subjects remained upright and awake throughout the night. When sleep was not permitted IOP was lowest at 3:00 a.m. (0300); when six of these subjects were permitted to sleep from 0600 to 0800, they showed a rapid and significant increase in IOP of up to 150%, whereas the remaining nine subjects showed (posturally induced) increases of up to 38%.  相似文献   
103.
104.
Studies using plaster models of teeth and photographs simulating the full range of occlusal conditions have found high agreement between measures of adolescent social acceptability of these conditions and perceived need for orthodontic treatment. This study examined the association between adolescents' acceptability of their own occlusal condition, severity of malocclusion, and likelihood of undergoing orthodontic treatment. The factors predicting the acceptability of occlusal condition of 13-yr-olds, as assessed by the SASOC scale, were measurements of acceptability of general physical appearance, and the severity of occlusal condition. Variability in SASOC scores appeared to be independent of gender, socioeconomic status, and ethnicity. Gender, and severity of occlusal condition were important differences between subjects who had received, planned, or were undergoing orthodontic treatment, and those who had not. Neither SASOC scores nor perceived need for treatment accounted for a significant proportion of the variance between these groups. Although adolescents seeking orthodontic treatment had a greater severity of malocclusion than those not, little difference was observed between these groups in acceptance of occlusal condition.  相似文献   
105.
106.
The impact of clinical risk factor-based absolute risk methods on the prevalence of high risk for osteoporotic fracture is unknown. We applied absolute risk methods to 6646 subjects and found that the prevalence of elderly women deemed to be at high risk increased substantially, whereas the overall prevalence was highly dependent on the threshold used to designate high risk. INTRODUCTION: Many groups have advocated using absolute risk methods that incorporate clinical risk factors to target patients for osteoporosis therapy. We examined how the application of such absolute risk classification systems influences the prevalence of those considered to be at high risk for osteoporotic fracture and compared these systems to one based solely on BMD. MATERIALS AND METHODS: Using 6646 subjects from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective, randomly selected, population-based cohort, we assessed three different systems for determining prevalence of high risk for osteoporotic fracture: a BMD-based system; a simplified risk factor system incorporating age, sex, BMD, and two clinical risk factors; and a comprehensive system, incorporating age, sex, BMD, and seven clinical risk factors. The 10-year absolute risks of incident fragility fracture were compared across systems using three different high-risk thresholds. RESULTS: The prevalence of a T score < or = -2.5 was 18.8% (95% CI: 17.7-19.9%) in women and 3.9% (95% CI: 3.0-4.7%) in men. Using a 15% 10-year risk of fracture threshold, the prevalence of women at high risk increased to 46.9% (95% CI: 45.4-48.4) and 42.5% (95% CI: 41.1-43.9) when the comprehensive and simplified risk factor classification systems were used, respectively. Using a 25% 10-year absolute risk threshold, the prevalence of high risk was similar to that of the BMD-based system, whereas the 20% threshold gave intermediate rates. All thresholds analyzed resulted in an increased prevalence of older women at high risk for fracture, whereas only the 15% 10-year risk of fracture threshold resulted in an increase in the prevalence of men at high risk. CONCLUSIONS: The application of risk factor-based systems results in an increased prevalence of older women at high risk. The prevalence of individuals at high risk may increase with changes to the methods used to determine those who are eligible for therapy. These data have important implications for the pattern of care and costs of treating osteoporotic fractures.  相似文献   
107.
ABSTRACT:Background: In 1996 a new model of maternity care characterized by continuity of midwifery care from early pregnancy through the postpartum period was implemented for women attending Monash Medical Centre, a tertiary level obstetric service, in Melbourne, Australia. This study's purpose was to assess the impact of this model on women's views and experiences of care during the antenatal, intrapartum, and postpartum periods compared with views of women receiving standard maternity care. Methods: One thousand low‐ and high‐risk women who booked at the antenatal clinic and met the eligibility criteria were randomly allocated to continuity of midwifery care from a group of seven midwives in collaboration with medical staff, or to standard care from a variety of midwives and medical staff. Women's views of care were measured by means of a postal questionnaire at four months after the birth. Results: Team midwifery care was associated with increased satisfaction with antenatal, intrapartum, and some aspects of postpartum care. The differences were most obvious for antenatal care. Conclusions: Continuity of midwifery care is realistically achievable in a tertiary obstetric referral service and is associated with increased satisfaction. (BIRTH 30:1 March 2003)  相似文献   
108.
109.
110.
Academic medical centers (AMCs) devote countless hours to studying the diagnosis and treatment of disease, yet little or no time to determining the factors that enhance or detract from physicians' professional fulfillment. This is unfortunate because physicians' degree of professional engagement, the quality of care they provide, and their tendency to burn out all depend on the fulfillment they find in work.Indeed, if AMCs are to thrive, it is vital to understand and promote the professional fulfillment of physicians. This article reviews the sources of professional fulfillment among physicians and outlines ways to enhance it within physicians' organizations.  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