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   30226篇
  免费   1906篇
  国内免费   113篇
耳鼻咽喉   328篇
儿科学   823篇
妇产科学   630篇
基础医学   4550篇
口腔科学   2751篇
临床医学   2406篇
内科学   5986篇
皮肤病学   662篇
神经病学   2388篇
特种医学   625篇
外国民族医学   1篇
外科学   3355篇
综合类   354篇
一般理论   8篇
预防医学   3418篇
眼科学   405篇
药学   2174篇
中国医学   295篇
肿瘤学   1086篇
  2023年   292篇
  2022年   694篇
  2021年   1128篇
  2020年   775篇
  2019年   980篇
  2018年   1146篇
  2017年   857篇
  2016年   863篇
  2015年   1007篇
  2014年   1316篇
  2013年   1591篇
  2012年   2404篇
  2011年   2677篇
  2010年   1402篇
  2009年   1049篇
  2008年   1730篇
  2007年   1637篇
  2006年   1493篇
  2005年   1243篇
  2004年   1079篇
  2003年   960篇
  2002年   867篇
  2001年   579篇
  2000年   637篇
  1999年   505篇
  1998年   183篇
  1997年   121篇
  1996年   126篇
  1995年   114篇
  1994年   93篇
  1993年   78篇
  1992年   235篇
  1991年   215篇
  1990年   204篇
  1989年   202篇
  1988年   180篇
  1987年   138篇
  1986年   127篇
  1985年   132篇
  1984年   103篇
  1983年   85篇
  1979年   87篇
  1978年   87篇
  1977年   46篇
  1975年   58篇
  1974年   65篇
  1973年   64篇
  1970年   65篇
  1969年   47篇
  1967年   59篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Within the context of WHO/CDS/RBM/2000, a survey was conducted in 2001 by the National Malaria Control Program of Benin. Following a well-thought-out choice, the survey took place simultaneously in health areas corresponding to epidemiological regions. Morbidity due to malaria is very high among children under five years admitted in external clinic (44.3% of cases) and (46.5%) for hospitalization. The crude rate of mortality is 129%. The use of non-impregnated bednet is usually met in three health areas, where 47.4% of the household have at least one non-impregnated bednet versus 5.4% of household with impregnated bednets. Percentage of pregnant women sleeping under an impregnated bednet and following chemoprophylaxis is respectively 43.3% and 3.8%. Results obtained at the end of this database survey in 2001 have facilitated the definition of indicators of the process, results and impact which remain very useful for the implementation of the monitoring and assessment system of "Roll Back Malaria" in Benin.  相似文献   
93.
Picture Archiving and Communication Systems (PACS) make possible the viewing of radiographic images on computer workstations located where clinical care is delivered. By the nature of their work this feature is particularly useful for emergency physicians who view radiographic studies for information and use them to explain results to patients and their families. However, the high cost of PACS diagnostic workstations with fuller functionality places limits on the number of and therefore the accessibility to workstations in the emergency department. This study was undertaken to establish how well less expensive personal computer-based workstations would work to support these needs of emergency physicians. The study compared the outcome of observations by 5 emergency physicians on a series of radiographic studies containing subtle abnormalities displayed on both a PACS diagnostic workstation and on a PC-based workstation. The 73 digitized radiographic studies were randomly arranged on both types of workstation over four separate viewing sessions for each emergency physician. There was no statistical difference between a PACS diagnostic workstation and a PC-based workstation in this trial. The mean correct ratings were 59% on the PACS diagnostic workstations and 61% on the PC-based workstations. These findings also emphasize the need for prompt reporting by a radiologist.  相似文献   
94.
95.
PAF-acether (PAF) or 2-methoxy-PAF (2-MX) caused a dose-dependent paw edema showing a 1: 25 ratio between their inflammatory activities. 2-MX caused a thrombocytopenia, whereas PAF did not alter the number of these cells. Both phospholipids induced reductions in total leukocyte count. Rat antiplatelet serum produced platelet depletion by PAF-induced paw edema was unaffected. The edema of 2-MX was significantly reduced by antiplatelet serum, under conditions where normal serum was inactive against the edema induced by PAF or 2-MX. Histopathological analysis of PAF and 2-MX-induced edema showed, in the first case, a small infiltrate of neutrophils, some lymphocytes, and several mastocytes around the vessels and, in the second, a neutrophilic infiltrate. These results suggest that PAF and 2-MX may produce edema through different mechanisms and that 2-MX causes edema in part through platelet activation.  相似文献   
96.
97.
Arbitrarily primed PCR (AP-PCR) was used to genotype 26 clinical isolates of Clostridium difficile previously analyzed by immunoblotting (IB) and 20 isolates typed by restriction endonuclease analysis (REA) with HindIII. Two levels of differentiation were achieved with the AP-PCR approach by use of two different arbitrary primers. With the 19-mer arbitrary primer T-7 (first level of differentiation), a good correlation was found between IB and AP-PCR typing. Twenty isolates grouped into six IB types were separated into seven major AP-PCR types. These seven AP-PCR groups were further discriminated into 12 subtypes after genotyping with the arbitrary primer PG-05 (second level of differentiation). The remaining six isolates, all of different IB types, showed a unique and distinct DNA banding pattern with both of the arbitrary primers, T-7 and PG-05. Twenty isolates representing 20 REA types from 15 REA groups were resolved into 13 AP-PCR DNA profiles with the arbitrary primer T-7. A good correlation was found at this level of differentiation between the major REA groups, Y and M, and AP-PCR typing. While AP-PCR with this primer failed to differentiate isolates in REA groups J, G, R, and B, AP-PCR with PG-05 resolved these four isolates into four distinct AP-PCR types. In addition, one of three M strains and one of four Y strains displayed a slightly different DNA banding pattern by AP-PCR (with PG-05) from that of the other strains in the group. We conclude that AP-PCR is a rapid and sensitive method which not only complements other typing schemes but also may be a substitute and prove to be especially suited for immediate epidemiological tracking of nosocomial infections due to C. difficile.  相似文献   
98.
99.
Association of Streptococcus bovis Bacteremia with Bowel Disease   总被引:4,自引:5,他引:4       下载免费PDF全文
We reviewed the medical records of 19 patients who had Streptococcus bovis bacteremia. Eight patients had diverticulosis, four had benign adenomatous colonic polyps, and three had adenocarcinomas of the gastrointestinal tract. Laboratory workers and clinicians should be aware of the association of S. bovis bacteremia and gastrointestinal disease.  相似文献   
100.
BACKGROUND: Risk factors for acute wheezing among children in subtropical areas are largely unknown. OBJECTIVE: To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old. METHODS: One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression. RESULTS: In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing. CONCLUSIONS: Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.  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