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   1210591篇
  免费   79614篇
  国内免费   2645篇
耳鼻咽喉   14604篇
儿科学   42186篇
妇产科学   32414篇
基础医学   169139篇
口腔科学   29850篇
临床医学   105311篇
内科学   231319篇
皮肤病学   24230篇
神经病学   98946篇
特种医学   48527篇
外国民族医学   305篇
外科学   185117篇
综合类   26840篇
一般理论   419篇
预防医学   98773篇
眼科学   25943篇
药学   83667篇
  3篇
中国医学   2666篇
肿瘤学   72591篇
  2018年   33693篇
  2017年   26696篇
  2016年   30906篇
  2015年   11970篇
  2014年   15743篇
  2013年   23713篇
  2012年   37050篇
  2011年   53788篇
  2010年   38236篇
  2009年   30166篇
  2008年   51183篇
  2007年   56348篇
  2006年   32864篇
  2005年   33822篇
  2004年   34552篇
  2003年   35059篇
  2002年   31739篇
  2001年   47732篇
  2000年   49108篇
  1999年   40914篇
  1998年   11767篇
  1997年   10696篇
  1996年   10563篇
  1995年   10165篇
  1994年   9512篇
  1993年   8859篇
  1992年   32692篇
  1991年   31953篇
  1990年   31496篇
  1989年   30289篇
  1988年   27515篇
  1987年   27653篇
  1986年   25783篇
  1985年   24921篇
  1984年   18708篇
  1983年   15815篇
  1982年   9637篇
  1981年   8607篇
  1979年   17152篇
  1978年   12425篇
  1977年   10482篇
  1976年   9980篇
  1975年   10322篇
  1974年   12530篇
  1973年   12011篇
  1972年   11032篇
  1971年   10237篇
  1970年   9525篇
  1969年   8848篇
  1968年   8215篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
221.
222.
Osteomyelitis, or the infection of the bone, presents a major complication in orthopedics and may lead to prolonged hospital visits, implant failure, and in more extreme cases, amputation of affected limbs. Typical treatment for this disease involves surgical debridement followed by long-term, systemic antibiotic administration, which contributes to the development of antibiotic-resistant bacteria and has limited ability to eradicate challenging biofilm-forming pathogens including Staphylococcus aureus—the most common cause of osteomyelitis. Local delivery of high doses of antibiotics via traditional bone cement can reduce systemic side effects of an antibiotic. Nonetheless, growing concerns over burst release (then subtherapeutic dose) of antibiotics, along with microbial colonization of the nondegradable cement biomaterial, further exacerbate antibiotic resistance and highlight the need to engineer alternative antimicrobial therapeutics and local delivery vehicles with increased efficacy against, in particular, biofilm-forming, antibiotic-resistant bacteria. Furthermore, limited guidance exists regarding both standardized formulation protocols and validated assays to predict efficacy of a therapeutic against multiple strains of bacteria. Ideally, antimicrobial strategies would be highly specific while exhibiting a broad spectrum of bactericidal activity. With a focus on S. aureus infection, this review addresses the efficacy of novel therapeutics and local delivery vehicles, as alternatives to the traditional antibiotic regimens. The aim of this review is to discuss these components with regards to long bone osteomyelitis and to encourage positive directions for future research efforts.  相似文献   
223.
224.
225.
226.

Purpose

To quantify eating disorder (ED) stability and diagnostic transition among a community-based sample of adolescents and young adult females in the United States.

Methods

Using 11 prospective assessments from 9,031 U.S. females ages 9–15 years at baseline of the Growing Up Today Study, we classified cases of the following EDs involving bingeing and purging: bulimia nervosa (BN), binge ED, purging disorder (PD), and subthreshold variants defined by less frequent (monthly vs. weekly) bingeing and purging behaviors. We measured number of years symptomatic and probability of maintaining symptoms, crossing to another diagnosis, or resolving symptoms across consecutive surveys.

Results

Study lifetime disorder prevalence was 2.1% for BN and roughly 6% each for binge ED and PD. Most cases reported symptoms during only one survey year. Twenty-six percent of cases crossed between diagnoses during follow-up. Among participants meeting full threshold diagnostic criteria, transition from BN was most prevalent, crossing most frequently from BN to PD (12.9% of BN cases). Within each disorder phenotype, 20%–40% of cases moved between subthreshold and full threshold criteria across consecutive surveys.

Conclusions

Diagnostic crossover is not rare among adolescent and young adult females with an ED. Transition patterns from BN to PD add support for considering these classifications in the same diagnostic category of disorders that involve purging. The prevalence of crossover between monthly and weekly symptom frequency suggests that a continuum or staging approach may increase utility of ED classification for prognostic and therapeutic intervention.  相似文献   
227.
Definitive radiotherapy is an effective single-modality in T1 glottic cancer. Hypofractionated schemes could offer excellent results in a shorter treatment period. We aimed to evaluate the clinical outcomes and toxicity comparing conventional vs. hypofractionated radiotherapy treatment in T1N0M0-glottic cancer. Between Jan-1st, 2005 and August-1st, 2017, in a prospective cohort study, with 10-year follow-up, 138 patients were treated with conventional schedule 2 Gy/day, total dose 70 Gy/7 weeks (N = 71) or hypofractionated schedule 2, 2–2, 25 Gy/day, total dose 63, 8–63 Gy/5, 5 weeks (N = 67). Endpoints were clinical-response rate, local relapse-free survival (LRFS), laryngectomy-free survival (LFS), toxicity rates, relapse-free survival (RFS), metastasis-free survival (MFS), second tumour-free survival (2TFS), and overall survival (OS). All patients showed a complete clinical response. No differences were found for LRFS (p = 0.869), LFS (p = 0.975), RFS (p = 0.767), MFS (p = 0.601), 2TFS (p = 0.293), or OS (p = 0.685). Acute toxicity for skin and mucosae was similar (p = 0.550 and p = 0.698). Acute laryngeal toxicity was higher in the hypofractionation group (p = 0.004), due to an increase in slight moderate grade. No differences in late laryngeal edema were found (p = 0.989). Radiotherapy offers high rate survival, local control, and larynx preservation after 5–10-year follow-up. A hypofractionation could be preferable, since it offers the same results as conventional with fewer treatment sessions.  相似文献   
228.
229.
OBJECTIVE: To investigate whether cardiovascular mortality related to obesity could be modified by physical activity. DESIGN: Mortality follow-up. SETTING: Population study. PARTICIPANTS: Participants in a health survey: 34 868 women and 32 872 men free from known cardiovascular disease or diabetes at baseline. MAIN OUTCOME MEASURES: Total cardiovascular mortality. MAIN RESULTS: During 16 years of follow-up, 3026 women and 3526 men had died from cardiovascular causes. In middle age, obesity [body mass index (BMI) of 30 or higher] was associated with increased risk of cardiovascular death, but the association weakened with age. After 70, there was no association between BMI and cardiovascular death. At all ages, a lower level of physical activity was associated with a higher cardiovascular mortality. In women with high physical activity, indicated by at least 30 min of moderate to vigorous activity more than once a week, cardiovascular mortality was only slightly higher in the obese compared to lean women (adjusted relative risk, 1.27; 95% confidence interval, 0.80-2.00). In men with high physical activity, cardiovascular mortality was, however, significantly higher among the obese (relative risk, 1.62; 95% confidence interval, 1.09-2.40). In both genders cardiovascular mortality was substantially higher in obese people who reported no regular physical activity compared to obese people with a high level of physical activity. CONCLUSION: In obese women, being highly active may, to a large extent, compensate for the risk-increasing effect of being obese, whereas in obese men who engage in a high level of physical activity, the risk of cardiovascular death may be higher than in lean and equally active men.  相似文献   
230.
PURPOSE: Our aim was to evaluate whether healthy dietary habits, physical activity and non-smoking are associated with less severe acute coronary syndromes and better short-term prognosis. SUBJECTS AND METHODS: From October 2003 to September 2004, 2172 patients (1649 males), hospitalized for severe acute coronary syndromes in six major hospitals in Greece were included in the study. The severity of severe acute coronary syndromes was assessed through troponin-I and maximum creatinine kinase MB levels, while 30-day recurrent event rate (death or rehospitalization for cardiovascular disease, angioplasty or coronary artery bypass surgery) was used to evaluate the prognosis of the patients. A 'healthy index' that assessed adherence to the Mediterranean diet, moderate alcohol intake, physical activity and abstinence from smoking was developed (range 0-4). RESULTS: One unit increment in the healthy index was associated with -12.4+/-2.4 ng/ml decrease in troponin I levels (P=0.001) and -9.7+/-2.5 ng/ml decrease in maximum creatinine kinase MB levels (P=0.001). The in-hospital mortality rate was 3.2% in males and 5.7% in females (i.e. overall 82 deaths, P=0.009); during the first 30 days following hospitalization the event rate was 15.7% in males and 16.3% in females (P=0.001). Values of the healthy index above one (i.e. presence of two or more protective factors) seemed to be associated with 44-84% lower risk of having recurrent events (P<0.001), even after various adjustments were made. CONCLUSION: Among patients who had had severe acute coronary syndromes, a healthy lifestyle seemed to be associated with less severe cardiac events and lower risk of death or rehospitalization 30 days after the event.  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