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   1293072篇
  免费   97538篇
  国内免费   1690篇
耳鼻咽喉   16605篇
儿科学   41938篇
妇产科学   35548篇
基础医学   193501篇
口腔科学   35104篇
临床医学   121329篇
内科学   254104篇
皮肤病学   27984篇
神经病学   104980篇
特种医学   47725篇
外国民族医学   266篇
外科学   182834篇
综合类   25952篇
现状与发展   3篇
一般理论   594篇
预防医学   107119篇
眼科学   28411篇
药学   94281篇
  7篇
中国医学   2081篇
肿瘤学   71934篇
  2019年   10784篇
  2018年   14411篇
  2017年   11125篇
  2016年   12055篇
  2015年   14010篇
  2014年   19104篇
  2013年   29038篇
  2012年   39380篇
  2011年   41951篇
  2010年   24353篇
  2009年   23471篇
  2008年   39488篇
  2007年   42184篇
  2006年   41699篇
  2005年   40909篇
  2004年   39286篇
  2003年   37730篇
  2002年   36683篇
  2001年   56321篇
  2000年   57270篇
  1999年   48390篇
  1998年   13752篇
  1997年   12540篇
  1996年   12906篇
  1995年   12216篇
  1994年   11351篇
  1993年   10627篇
  1992年   38360篇
  1991年   37853篇
  1990年   36594篇
  1989年   35381篇
  1988年   32830篇
  1987年   32176篇
  1986年   30651篇
  1985年   28907篇
  1984年   22081篇
  1983年   19289篇
  1982年   11520篇
  1979年   21030篇
  1978年   15476篇
  1977年   12875篇
  1976年   11912篇
  1975年   12866篇
  1974年   15645篇
  1973年   15411篇
  1972年   14571篇
  1971年   13593篇
  1970年   12819篇
  1969年   12100篇
  1968年   11260篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
In 1985 an outbreak of ornithosis affected 13 of 80 (16%) workers in a duck-processing plant. New employees were three times more likely to become cases than established employees. The highest attack rate was in those on the production line. Following the outbreak, an occupational health scheme was set up to monitor the health of new recruits to the company. Serological evidence of recent infection was demonstrated in 18 of 37 (49%) new employees tested in the first 3 months of employment. Five (14%) also had clinical evidence of ornithosis. Veterinary investigation of the ducks demonstrated a high proportion with asymptomatic chlamydial infection. It is suggested that ornithosis may be more common in duck processors than is currently supposed. Strategies to reduce occupational risks are discussed.  相似文献   
102.
Premalignant lesions of the penis include cutaneous horn, balanitis xerotica obliterans, and leukoplakia. The true incidence of progression of each of these to squamous-cell carcinoma is unknown. Bowenoid papulosis, erythroplasia of Queyrat, and Bowen's disease are histologically identical to in situ carcinoma. Although the first is consistently benign, the latter two regularly evolve into invasive cancer. Malignant scrotal lesions include squamous-cell carcinoma, liposarcoma, leiomyosarcoma, basal-cell carcinoma, extramammary Paget's disease, erythroplasia of Queyrat, malignant melanoma, and metastases. Hemangioma can be confused with carcinoma.  相似文献   
103.
104.
105.
Three hundred and twenty samples of subgingival plaque were obtained from 80 caucasian girls, ranging from 10 to 13 years of age. The samples were analyzed to verify the influence of age upon colonization of the gingival sulcus by microorganisms potentially pathogenic to the periodontal tissues. The gingival and plaque status were evaluated through the gingival index (GI) and plaque index (PlI) and the microflora was assessed by the enzymatic method benzoyl-arginine-naphthylamide (BANA). The results of the BANA test were positive for 62.50% of the tested individuals and 40% of the examined sites. The influence of age was statistically significant on BANA reactivity, and the number of positive sites was greater at 11 (57.5%) than at 12 years (28.8%).  相似文献   
106.
Diffusely adhering Escherichia coli (E. coli) strains (DAEC) represent a potential cause of diarrhoea in infants, and the detection of type three secretion system (TTSS) genes in DAEC would substantiate their pathogenic nature. In this work, four isolates of DAEC, recovered from stools of diarrhoeic children, were analysed by PCR, in order to detect the presence of TTSS genes. Primers targeted to the escC, escJ, escN and escV, some of the most conserved TTSS genes in enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), were used in order to verify the occurrence of homologous genes in our DAEC isolates. By this approach, we were able to characterise DNA fragments corresponding to putative escJ and escN genes in all DAEC isolates. Furthermore, DNA fragments homologous to the escC and escV genes were also amplified from all isolates. Besides the similarity found among the DAEC esc homologues with EPEC and EHEC esc genes, the nucleotide sequence analysis of the flanking regions of the amplified DNA fragments suggests that the putative DAEC esc genes are organised in the same manner as observed in EPEC and in EHEC strains. The results described here provide strong evidence for the presence of a TTSS in the DAEC strains analysed, implicating a pathogenic nature of these isolates.  相似文献   
107.
108.
We tested the urine of 30 infants 6 weeks to 7 months of age after they received standard 10-micrograms (0.5-ml) doses of HbOC (HibTITER) Haemophilus influenzae b (Hib) conjugate vaccine for the presence of Hib antigenuria using a commercially available latex particle agglutination assay (Directigen). Urines were collected within 1 hour, from 1 to 3 hours, at 24 hours and at 3, 6 and 9 days after vaccine administration and reactions were quantitated from 0 to 3+. In contrast to previous studies in older children which showed little or no antigenuria following HbOC vaccination, our study shows that in infants intense Hib antigenuria is evident within 2 to 3 hours and persists 3 days after vaccine administration and that less intense antigenuria may be detected in some infants for several days. With efficacious vaccines now being used in 2- to 6-month-old infants, invasive Hib disease may soon be limited to infants of this age just before their seroconversion. It should be recognized that antigenuria occurs for several days after vaccination with Hib conjugate vaccines and that it could be erroneously interpreted as evidence of invasive Hib infection.  相似文献   
109.
We describe a familial case of Marfan's syndrome with associated intrathoracic stomach detected during the neonatal period. The patient developed a primitive leukemia at 3 months of age. Acute leukemia in a patient with Marfan's syndrome has not previously been reported.  相似文献   
110.
The decoction of Sclerocarya birroea Hochst. shows hypoglycaemic effects, an increase in plasma IRI in normal rats and an incremented oral-glucose tolerance. The decoction is also active against diet-induced hypercholesterolaemia.  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