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   18836篇
  免费   2191篇
  国内免费   357篇
耳鼻咽喉   392篇
儿科学   939篇
妇产科学   1093篇
基础医学   1793篇
口腔科学   185篇
临床医学   1966篇
内科学   2678篇
皮肤病学   161篇
神经病学   868篇
特种医学   473篇
外国民族医学   3篇
外科学   1234篇
综合类   1309篇
现状与发展   2篇
预防医学   2782篇
眼科学   501篇
药学   1914篇
  13篇
中国医学   369篇
肿瘤学   2709篇
  2024年   72篇
  2023年   444篇
  2022年   727篇
  2021年   960篇
  2020年   941篇
  2019年   945篇
  2018年   853篇
  2017年   860篇
  2016年   916篇
  2015年   867篇
  2014年   1324篇
  2013年   1849篇
  2012年   1057篇
  2011年   1115篇
  2010年   900篇
  2009年   856篇
  2008年   873篇
  2007年   815篇
  2006年   699篇
  2005年   595篇
  2004年   498篇
  2003年   491篇
  2002年   343篇
  2001年   314篇
  2000年   231篇
  1999年   236篇
  1998年   204篇
  1997年   187篇
  1996年   140篇
  1995年   134篇
  1994年   121篇
  1993年   100篇
  1992年   108篇
  1991年   76篇
  1990年   81篇
  1989年   53篇
  1988年   57篇
  1987年   50篇
  1986年   41篇
  1985年   55篇
  1984年   36篇
  1983年   30篇
  1982年   29篇
  1981年   27篇
  1980年   16篇
  1979年   11篇
  1978年   11篇
  1977年   8篇
  1976年   9篇
  1973年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A cross-sectional study was carried out in two geographic regions of Mexico - Oaxaca (rural area) and Mexico City (urban area) - to determine the main factors for predicting participation in Cervical Cytology Screening Programs (CCSP), in populations with high mortality due to cervical cancer. We included 4,208 women aged between 15 and 49 years, randomly selected through a national household-sample frame. Knowledge of what the Pap test is used for strongly predisposes use of CCSP in Mexico City (odds ratio [OR] = 46.1, 95 percent confidence interval [CI] = 33.1-64.1) and Oaxaca state (OR = 61.5, CI = 42.0-89.9), as well as high socioeconomic level (Mexico: OR = 2.0, CI = 1.1-7.6; Oaxaca: OR = 4.1, CI = 3.1-5.3), high education level (Mexico: OR = 3.6, CI = 1.5-8.8; Oaxaca: OR = 5.3, CI = 2.8-10.0), and access to social security (Mexico: OR = 1.7, CI = 1.4-2.2; Oaxaca: OR = 2.2, CI = 1.8-2.7). Low coverage of the CCSP is confirmed as an important problem in Mexico.  相似文献   
72.
Amadori A, Gentilini P, Bucchi L, Innocenti MP, Falcini F, Martini F, Fabbri M, Liverani M, Danesi S, Piantini B, Milandri C, Saragoni L, Amadori D. A registry-based study of follow-up failures in the screening experience of cervical cancer patients. Int J Gynecol Cancer 1998; 8 : 251–256.
Although all components of cervical screening are at risk of error, most studies of the previous screening experience of cervical cancer patients addressed only the false negative cytology results. Other reports showed the importance of screening failures not attributable to the Pap smear. We studied the relative frequency of all types of error observed in the screening history of 115 cervical cancer cases (median age, 60; range, 23–89) registered with the population-based Romagna Cancer Registry in Forlì (northern Italy) between 1986 and 1993. For each case, a search was made for all cytology, colposcopy, biopsy, and treatment reports issued prior to diagnosis. Eighty-one (70.4%) patients had never had a Pap smear. Eight (7.0%) were diagnosed at their first test. Twenty-six patients (22.6%) had had at least one previous smear. Among these, 10 were screened during the five years prior to diagnosis: three patients had false negative cytology results, one patient did not comply with the recommendation for an early repeat smear, two patients with positive cytology results underwent colposcopy with considerable delay (7 and 9 months), one patient had a negative colposcopy (without biopsy), and three patients had biopsies histologically reported as negative. An overview of the registry-based studies of screening histories reported so far from Italy (total number of cases 262) demonstrated that patients with serious shortcomings in follow-up after smear test, colposcopy, biopsy, clinical assessment, and treatment accounted for a substantial proportion of screening failures.  相似文献   
73.
Objective: To assess the risk of neoplastic development among persons exposed to scalp irradiation. Study Design: Historical cohort study initially; prospective follow-up subsequently. Method: Two control groups—population and siblings—matched for age, sex, ethnic origin, and year of immigration. Follow-up from time of irradiation (1950s) until the end of 1991. Linkage with nationwide cancer registry. Results: A 4.5–fold incidence of cancer (P < .01) and a 2.6–fold increase of benign tumors were noted. The mean length of latency period until tumor development was 11 years for malignant tumors and 21.5 years for benign. A clear dose response effect for both cancer and benign tumors was demonstrated. Conclusions: The study confirms the role of radiation in salivary gland carcinogenesis. It indicates a need for better awareness, a comprehensive examination, and long-term follow-up of patients who have been subjected to head and neck radiation.  相似文献   
74.
Computed tomography scans, including thin-section high-resolution computed tomography (HRCT), occasionally fail to differentiate between small non-cancerous nodules from lung cancers. We describe nine such lesions ( < 20 mm in diameter) initially identified through our screening program for lung cancer using CT scanning. Pathological diagnoses included nodular fibrosis (n = 4), granuloma (n = 1), cryptococcoma (n = 1), localised organising pneumonia (n = 1), inflammatory pseudo-tumour (n = 1) and sclerosing haemangioma (n = 1). High-resolution CT findings, together with MRI findings with contrast-enhanced dynamic studies, were retrospectively evaluated. Additional cases should be identified and radiologically characterised in order to reduce the number of non-cancerous tumours that are treated by unnecessary surgery. Received: 28 February 2000; Accepted: 29 February 2000  相似文献   
75.
新生儿脐血红细胞葡萄糖6磷酸脱氢酶缺乏筛查结果分析   总被引:4,自引:0,他引:4  
目的 了解广东省东莞市莞城地区新生儿脐血红细胞葡萄糖6磷酸脱氢酶(G-6-PD)缺乏的发生率。方法 9676例活产新生儿生后即取脐血,采用定量法测定红细胞G6PD/6PGD的比值。低于1.0者为G-6-PD缺乏。结果 测得G-6-PD缺乏的患儿265例,总发生率为2.74%。其中男230例,发生率为4.07%;女35例,发生率为0.87%。男性发生率明显高于女性(χ^2=90.75,P<0.001)。结论 脐血G-6-PD活性筛查,能比较准确地检测出G-6-PD缺乏患儿,指导临床对其并发症进行早期干预,避免智力低下等后遗症的发生,提高人口素质。  相似文献   
76.
OBJECTIVES: To investigate the impact of an ultrasound dating service on obstetric services. METHODS: A prospective trial with 3009 unselected women presenting for antenatal care at two Midwife Obstetric Units in a socioeconomically deprived urban area, South Africa. In the study unit, student ultrasonographers provided a basic ultrasound service. In the control unit, obstetric ultrasound was only available for specific indications. The main outcome measures were number of antenatal visits and referrals for fetal surveillance. RESULTS: The two cohorts were comparable except for the number of primigravidas but stratified analysis according to parity did not affect the results. Ultrasonography did not alter pregnancy outcome but reduced the number of perceived preterm labors/ruptured membranes (12.0 vs. 16.7%, P<0.003), post-term deliveries (8.1 vs. 10.8%, P<0.04) and referrals for fetal surveillance [15.9 vs. 29.6%, P<0.000, RR 0.79 (0.71-0.88)]. CONCLUSIONS: This community-based basic ultrasound service significantly reduced referrals to a regional center for fetal surveillance and delivery.  相似文献   
77.
目的 了解早期治疗对先天性甲状腺功能低下症预后的影响及新生儿筛查工作的意义.方法 对在湖南省妇幼保健院治疗的57例甲低患儿进行数年的追踪观察,并评价其体格发育和智力水平.结果 3个月以前开始治疗者体格发育及智力可达到同龄儿童正常水平,治疗越早,预后越好.结论 早期治疗可明显改善预后,减少残疾儿童的发生,同时提示新生儿筛查工作对提高人口素质有重要意义.  相似文献   
78.
Well-organised cervical screening programmes have reduced the mortality from cervical cancer by up to 50% in the developed world. Despite the successful development of human papilloma virus vaccines, there is likely to remain a need for cervical screening for the foreseeable future. In contrast, the value of mass screening for ovarian cancer remains unproven, although current screening methods can detect early-stage disease in asymptomatic individuals. Breast screening does appear to be associated with a reduction in mortality in the long term but paradoxically may increase death rates in young women in the short term. Testing for sexually transmitted infections is effective in reducing morbidity but tends to be selective at present because of concerns over the cost and psychosocial implications of general population screening.  相似文献   
79.
This review provides a summary of the cost-effectiveness, clinical utility, performance, and interpretation of screening helical cervical spine CT for trauma patients. Recent evidence supports the use of helical CT as a cost-effective method for screening the cervical spine in high-risk trauma patients. Screening cervical spine CT can be performed at the time of head CT to lower the cost of the evaluation, and when all short- and long-term costs are considered, CT may actually save money when compared with traditional radiographic screening. In addition to having higher sensitivity and specificity for cervical spine injury, CT screening also allows more rapid radiological clearance of the cervical spine than radiography. Patients who are involved in high-energy trauma, who sustain head injury, or who have neurological deficits are candidates for CT screening. Screening with CT may enhance detection of other potentially important injuries of the cervical region. Received: 17 March Revision requested: 14 April 2000 Revision received: 19 July 2000 Accepted: 19 July 2000  相似文献   
80.
Patients with Beckwith‐Wiedemann spectrum (BWSp) undergo quarterly alpha‐fetoprotein measurement for hepatoblastoma (HB) screening up to 4 years of age, paralleling the epidemiology of nonsyndromic HB. However, specific data on the timing of HB development in BWSp are lacking. Here we compare the timing of presentation of HBs in BWSp with a control cohort of consecutive HB cases, demonstrating that halving screening duration of screening procedures in BWSp likely will not impact its effectiveness.  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