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   998篇
  免费   66篇
  国内免费   7篇
耳鼻咽喉   5篇
儿科学   12篇
妇产科学   30篇
基础医学   86篇
口腔科学   37篇
临床医学   126篇
内科学   155篇
皮肤病学   8篇
神经病学   81篇
特种医学   47篇
外科学   203篇
综合类   17篇
预防医学   77篇
眼科学   4篇
药学   61篇
中国医学   4篇
肿瘤学   118篇
  2023年   4篇
  2022年   8篇
  2021年   35篇
  2020年   13篇
  2019年   26篇
  2018年   39篇
  2017年   24篇
  2016年   44篇
  2015年   24篇
  2014年   36篇
  2013年   46篇
  2012年   79篇
  2011年   68篇
  2010年   33篇
  2009年   40篇
  2008年   58篇
  2007年   55篇
  2006年   48篇
  2005年   37篇
  2004年   36篇
  2003年   52篇
  2002年   41篇
  2001年   22篇
  2000年   21篇
  1999年   13篇
  1998年   8篇
  1997年   11篇
  1996年   9篇
  1995年   6篇
  1994年   4篇
  1992年   10篇
  1991年   13篇
  1990年   15篇
  1989年   6篇
  1988年   7篇
  1987年   15篇
  1985年   8篇
  1984年   5篇
  1983年   3篇
  1980年   4篇
  1979年   2篇
  1977年   2篇
  1976年   3篇
  1975年   4篇
  1974年   6篇
  1973年   4篇
  1972年   2篇
  1967年   3篇
  1966年   4篇
  1960年   2篇
排序方式: 共有1071条查询结果,搜索用时 437 毫秒
1.

Background

Most elderly trauma patients suffer blunt head injury and many utilize antithrombotic (AT) medications. The utility of delayed CT-head (D-CTH) in neurologically intact elderly patients using AT who have an intracranial hemorrhage (ICH) on presentation is unknown. We hypothesized that D-CTH would not alter clinical management and aimed to evaluate the role of D-CTH in this population.

Methods

A retrospective cohort study was performed. Patients ≥65 years sustaining blunt head injuries from January 2010 to July 2017 were identified using our level 1 trauma center database. AT-patients presenting with ICH who underwent D-CTH were included. Patients with worsened ICH were compared to those with stable to improved ICH on D-CTH. AT-patients were compared to a cohort of non-AT patients. Fisher’s Exact and Mann-Whitney U tests were utilized and a power analysis conducted.

Results

137?A?T and 34 non-AT patients were identified. There was no difference in hemorrhage progression or appearance of new ICH. No patient had a change in management from D-CTH in either cohort. AT-patients were slightly older (p?<?0.001), but cohorts were otherwise similar.50 AT-patients with worsened ICH were compared to 87 with stable ICH. There was no difference in cohort demographics. Hemorrhage progression did not vary with type of AT used but did increase if multiple types of synchronous ICH were present (p?<?0.001).

Conclusions

Our data supports abstaining from routine D-CTH of elderly ICH patients with an intact neurologic examination who are utilizing aspirin, clopidogrel or warfarin. Conclusions cannot be drawn regarding new oral anticoagulants (NOACs) given low enrollment. Further multicenter study is required to provide adequate power and detect small levels of management change.  相似文献   
2.
3.
STUDY OBJECTIVE--To assess the impact of a breast clinic on a specific target population and evaluate early diagnosis performance indicators for breast cancer in the presence of a self referral policy. DESIGN--Women living in Florence between 1980 and 1989 who had undergone mammography at a self referral breast clinic were studied. Main outcome measures were the use of mammography in relation to age, symptoms, and the interval between two subsequent tests, and early diagnosis performance indicators were the detection rate (DR), the prevalence/incidence ratio, and the proportion of early detected cancers. Performance indicators were compared with those from formal screening programmes. SETTING--Florence, Italy. PATIENTS--All mammograms performed at the clinic from 1980-89 in 40-69 year old women living in Florence were examined (n = 42,226). Records included the date of birth and of the examination, the reason for testing (asymptomatic/presence of pain/presence of symptoms other than pain), and the TNM classification for breast cancer cases. MAIN RESULTS--The total number of mammograms performed per annum increased by 70% over the decade, but much of this was routine repeat mammography (54.1% in 1989). Rates of first examinations in asymptomatic women increased in the second half of the decade from 17 per 1000 in 1985 to 31 per 1000 in 1989. Mammographic coverage decreased with increasing age from 12.6% in 40-49 year olds to 6.0% in 60-69 years old. Performance indicators of the activity in asymptomatic women were comparable with those expected in service screening. The proportion of not advanced cancers detected in asymptomatic women was 62.3% with a DR of 5.3 per 1000, and the average prevalence/incidence ratio was 2.9. CONCLUSIONS--High quality mammography performed in a breast clinic in self referred asymptomatic women can achieve as good results as a formal invitation screening service. Only a few of these women will benefit, but those who do are likely to be younger (40-49 year old women).  相似文献   
4.
A case of sclerosing epithelioid fibrosarcoma and its appearance on MRI is presented. The tumor showed a zonal architecture on MRI with a large central core of very low signal intensity and a peripheral rim of intermediate to high signal intensity on T1- and T2-weighted spin echo pulse sequences. The core showed decreased cellularity with dense collagen deposition on histologic examination, and the peripheral zone increased cellularity with increased nuclear atypia. The presence of a prominent region of very low signal intensity on T1- and T2-weighted images can be seen with neural tumors, giant cell tumor of the tendon sheath, aggressive fibromatosis, and, in rare instances, with soft tissue sarcomas rich in collagen.  相似文献   
5.
PURPOSE: Studies have shown that medical students become more cynical and less altruistic as they advance in training. However, these studies were conducted in traditional medical schools, and many used unvalidated tools. This study examined students' attitudes in a problem-based learning (PBL) curriculum using reliable and valid measures. METHOD: Medical students and PGY-1 residents at Mercer University School of Medicine in Macon, Georgia, completed Wrightsman's Philosophies of Human Natures Scale (PHNS) in 1999 and 2000. Chronbach's alpha assessed internal reliability among subscales, and test-retest reliability coefficients confirmed acceptable reliability. For 114 students who completed both surveys, changes in PHNS scores were analyzed, with particular attention to the subscales of trustworthiness, altruism, and cynicism. RESULTS: Students assessed at the beginning of their second year increased the extent to which they believed people are trustworthy and increased their beliefs in how altruistic people are. They also showed a significant decrease in cynicism. There was not a significant change in trustworthiness, altruism, or cynicism among the participants beyond first year. In general, female students held less cynical views about others and believed people to be more trustworthy. CONCLUSIONS: Contrary to prior reports, this study found that more advanced trainees were not more cynical or less altruistic than their more junior counterparts. Indeed, a significant and positive change of attitudes among the participants during their first year of medical school refuted earlier reports. Thus, results of earlier studies and the effect of a PBL curriculum on attitudes of medical students need to be re-examined.  相似文献   
6.
7.
8.
In Italy, where no national screening program for cervical cancer exists, organized programs have developed on a local basis. We performed the first survey of existing organized programs by mailing a standard questionnaire to a large network of possibly involved services. For the present survey, a program was defined as organized if personal invitations were sent. We identified 29 already active organized programs and 4 others in a starting phase. The target population of active programs included 2,074,820 women in the age range 25-64 years, corresponding to 13.5% of the Italian female population of the same age. The situation is rapidly evolving since many regional programs are being implemented. Most programs followed Italian and European recommendations as regards the age limits, interval between screening rounds, presence of a fail-safe system for women referred for colposcopy, presence of protocols for diagnostic workup and treatment, and presence of referral centers for such phases. However, many programs did not meet national guidelines as regards the size of laboratories interpreting smears, which were frequently small. Second-level referral centers also frequently had a very small activity. The average (weighted for size of the invited population) compliance to invitation and coverage (proportion of women with at least one test in the last 3 years) was 32.6% and 66.0%, respectively, therefore needing to be improved. Compliance to colposcopy (weighted for number of referred women) was 81.4%. We found a very high variability in the proportion of women referred for colposcopy that could only be partly explained by different referral protocols and could depend on different criteria of smear interpretation: the average (weighted for number of tested women) was 2.01%. A need for improvement in the process of evaluation and for homogenization of criteria of cytology interpretation was identified: work in this regard is on-going.  相似文献   
9.
Screening with faecal occult blood test (FOBT) has been shown to be effective in reducing mortality from colorectal cancer. Tuscany was the first region in Italy in which a screening programme for colorectal cancer by FOBT was initiated region-wide. The aim of the paper was to describe organizational aspects, a quality control model and the results of this experience. From June 2000 to December 2001, 192583 subjects aged 50-70 were invited to undergo a 1-day immunochemical test without any dietary restriction. A total of 78505 subjects (41%) performed the screening test, of whom 4537 responders had a positive test result (5.8%). Among them, 1122 refused any form of assessment or underwent a colonoscopy outside the screening referral centres, with an overall assessment compliance of 75.3%. Malignancies were found in 193 patients and at least a high-risk adenomatous polyp in 692 patients. In about a quarter of the positive subjects who underwent assessment, cancer or high-risk adenoma was detected. In conclusion, data from this experience supported the feasibility of biennial colorectal screening programme by FOBT, particularly regarding invitation compliance and positivity rate. Further efforts are necessary to implement screening extension and to improve data collection.  相似文献   
10.
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