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   1059篇
  免费   66篇
  国内免费   16篇
耳鼻咽喉   7篇
儿科学   25篇
妇产科学   11篇
基础医学   182篇
口腔科学   5篇
临床医学   86篇
内科学   222篇
皮肤病学   30篇
神经病学   90篇
特种医学   14篇
外科学   121篇
综合类   24篇
一般理论   1篇
预防医学   161篇
眼科学   8篇
药学   81篇
中国医学   3篇
肿瘤学   70篇
  2024年   1篇
  2023年   15篇
  2022年   28篇
  2021年   39篇
  2020年   21篇
  2019年   43篇
  2018年   37篇
  2017年   24篇
  2016年   35篇
  2015年   44篇
  2014年   44篇
  2013年   58篇
  2012年   82篇
  2011年   101篇
  2010年   50篇
  2009年   47篇
  2008年   57篇
  2007年   64篇
  2006年   67篇
  2005年   68篇
  2004年   49篇
  2003年   53篇
  2002年   47篇
  2001年   8篇
  2000年   4篇
  1999年   1篇
  1998年   5篇
  1997年   5篇
  1996年   8篇
  1995年   2篇
  1994年   2篇
  1993年   5篇
  1992年   2篇
  1991年   1篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   4篇
  1985年   5篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1968年   1篇
排序方式: 共有1141条查询结果,搜索用时 234 毫秒
101.
OBJECTIVES: To assess the relationships between current smoking status and psychosocial working conditions. METHODS: A cross-sectional population-based telephone survey was conducted (66% response rate, N = 1,101). Job stress was measured using the demand/control, effort/reward imbalance (ERI), and job pressure models. Multiple regression modelling was conducted for smoking status (current versus non-smokers, and a more restricted analysis of current versus former-smokers) and daily smoking intensity outcomes in relation to job stress measures, working hours, shift work, and other independent variables. RESULTS: After adjustment for age, education, martial status, and hostility, high job strain was positively associated with current smoking in men only. Employment in active jobs was associated with decreased odds of smoking among women only. High strain jobs were associated with decreased odds of current smoking compared to former smoking in women. In men, extreme and moderate job pressure were related to current smoking compared to current non-smoking, and moderate job pressure was associated with current smoking compared with former smokers. Other working conditions associated with smoking were excessive working hours in men and physical demand in women. Daily smoking intensity in current smokers was associated with high psychological demand and with ERI in women. CONCLUSIONS: These results suggest that job stress is related to smoking status at the population level, with different patterns in men and women.  相似文献   
102.
103.

Aims

Multiple genetic alterations, including alternative lengthening of telomeres (ALT) and NOTCH mutations, have been described in angiosarcoma. Loss of α‐thalassaemia/mental retardation syndrome X‐linked (ATRX) and death domain‐associated protein 6 (DAXX) expression is frequently associated with the ALT phenotype. Additionally, inhibition of NOTCH signalling induces the development of malignant vascular tumours in mice, indicating a tumour suppressive role of the NOTCH pathway in the pathogenesis of angiosarcoma. The aim of this study was to evaluate the immunohistochemical expression of ATRX, DAXX and NOTCH receptors (NOTCH1 and NOTCH2) in a large cohort of angiosarcomas, and study their clinicopathological and prognostic significance.

Methods and results

One hundred and forty cases of angiosarcoma were stained for ATRX, DAXX, NOTCH1 and NOTCH2. ATRX loss (<10% labelling) was seen in seven of 118 (6%) cases, and was more frequent in deep soft tissue tumours than in other body sites (P = 0.004). Angiosarcomas with ATRX loss were associated with worse event‐free survival than angiosarcomas with retained ATRX expression (P = 0.003). DAXX was retained in all specimens examined. Decreased NOTCH1 expression (≤1+ intensity) was seen in 29 of 123 (24%) cases, and was associated with a cutaneous site of origin (P = 0.013) and advanced disease (P = 0.026). NOTCH2 expression was decreased in 16 of 103 (16%) cases, was associated with visceral tumours (P = 0.001), and correlated with worse disease‐specific survival (P = 0.033).

Conclusions

ATRX, NOTCH1 and NOTCH2 expression varies in angiosarcomas and shows significant correlations with site of origin and poor clinical outcome, thus highlighting the biological heterogeneity within this tumour type.  相似文献   
104.
Experimental autoimmune encephalomyelitis (EAE) is mediated by autoantigen-specific T cells dependent on critical costimulatory signals for their full activation and regulation. We report that the programmed death-1 (PD-1) costimulatory pathway plays a critical role in regulating peripheral tolerance in murine EAE and appears to be a major contributor to the resistance of disease induction in CD28-deficient mice. After immunization with myelin oligodendrocyte glycoprotein (MOG) there was a progressive increase in expression of PD-1 and its ligand PD-L1 but not PD-L2 within the central nervous system (CNS) of mice with EAE, peaking after 3 wk. In both wild-type (WT) and CD28-deficient mice, PD-1 blockade resulted in accelerated and more severe disease with increased CNS lymphocyte infiltration. Worsening of disease after PD-1 blockade was associated with a heightened autoimmune response to MOG, manifested by increased frequency of interferon gamma-producing T cells, increased delayed-type hypersensitivity responses, and higher serum levels of anti-MOG antibody. In vivo blockade of PD-1 resulted in increased antigen-specific T cell expansion, activation, and cytokine production. Interestingly, PD-L2 but not PD-L1 blockade in WT animals also resulted in disease augmentation. Our data are the first demonstration that the PD-1 pathway plays a critical role in regulating EAE.  相似文献   
105.

OBJECTIVE:

Smoking prevalence is frequently estimated on the basis of self-reported smoking status. That can lead to an underestimation of smoking rates. The aim of this study was to evaluate the difference between self-reported smoking status and that determined through the use of objective measures of smoking at a pulmonary outpatient clinic.

METHODS:

This was a cross-sectional study involving 144 individuals: 51 asthma patients, 53 COPD patients, 20 current smokers, and 20 never-smokers. Smoking status was determined on the basis of self-reports obtained in interviews, as well as through tests of exhaled carbon monoxide (eCO) and urinary cotinine.

RESULTS:

All of the asthma patients and COPD patients declared they were not current smokers. In the COPD and asthma patients, the median urinary cotinine concentration was 167 ng/mL (range, 2-5,348 ng/mL) and 47 ng/mL (range, 5-2,735 ng/mL), respectively (p < 0.0001), whereas the median eCO level was 8 ppm (range, 0-31 ppm) and 5 ppm (range, 2-45 ppm), respectively (p < 0.05). In 40 (38%) of the patients with asthma or COPD (n = 104), there was disagreement between the self-reported smoking status and that determined on the basis of the urinary cotinine concentration, a concentration > 200 ng/mL being considered indicative of current smoking. In 48 (46%) of those 104 patients, the self-reported non-smoking status was refuted by an eCO level > 6 ppm, which is also considered indicative of current smoking. In 30 (29%) of the patients with asthma or COPD, the urinary cotinine concentration and the eCO level both belied the patient claims of not being current smokers.

CONCLUSIONS:

Our findings suggest that high proportions of smoking pulmonary patients with lung disease falsely declare themselves to be nonsmokers. The accurate classification of smoking status is pivotal to the treatment of lung diseases. Objective measures of smoking could be helpful in improving clinical management and counseling.  相似文献   
106.
107.
We report the case of a 56-year-old woman with a history of rheumatic heart disease. The clinical, electrocardiographic, and radiologic findings suggested mitral stenosis. Left atrial obstructive myxoma simulating a thrombus was found by transthoracic echocardiography (TTE). The diagnosis was established by use of transesophageal echocardiography (TEE), confirmed after surgery and by anatomical investigation. Cardiac myxoma associated with mitral stenosis may be difficult to diagnose accurately using TTE. The advantage of TEE in this case and in patients with mitral stenosis is emphasized.  相似文献   
108.

Background

Acute appendicitis is the most common indication for acute surgical abdominal intervention. In this study, we analyzed the gender correlation with demographic, epidemiologic, diurnal, and seasonal trends in relation to the incidence and management of patients with acute appendicitis in our medical center.

Methods

Data of patients, 18?years of age or older who underwent emergency appendectomies at the Rabin Medical Center during the last 13?years, were collected. The data collected included demographic parameters, hospitalization, procedures, and use of preoperative imaging.

Results

Data were available for 3,736 patients. Males had more appendicitis attacks than females (p?<?0.0001), whereas females had more normal appendixes than males (p?<?0.0001). The overall rate of normal appendixes was 19.6?%, with a decline in the past 10?years from a yearly average of 23.5?% between 1998 and 2002 to 15?% between 2003 and 2007 (p?<?0.0001) with a reverse correlation with the preoperative use of abdominal CT. A distinct seasonal pattern was observed; more appendectomies for acute appendicitis occurred during the summer months (p?<?0.0001). Ten percent of patients had a complicated course with a mortality rate of 0.33?%; most of them were elderly, male/female ratio 0.4.

Conclusions

We found distinct gender, epidemiological, seasonal, and diurnal trends influencing the incidence of acute appendicitis. The incidence rate of false-positive surgery has been gradually declining, probably due to the increased use of preoperative abdominal CT and ultrasound. Acute appendicitis was more common in males and during the summer months.  相似文献   
109.
110.
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