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   5435篇
  免费   465篇
  国内免费   18篇
耳鼻咽喉   45篇
儿科学   192篇
妇产科学   116篇
基础医学   620篇
口腔科学   126篇
临床医学   633篇
内科学   1192篇
皮肤病学   60篇
神经病学   450篇
特种医学   279篇
外科学   823篇
综合类   109篇
一般理论   3篇
预防医学   409篇
眼科学   119篇
药学   309篇
中国医学   6篇
肿瘤学   427篇
  2023年   36篇
  2021年   93篇
  2020年   64篇
  2019年   69篇
  2018年   86篇
  2017年   82篇
  2016年   63篇
  2015年   87篇
  2014年   129篇
  2013年   246篇
  2012年   203篇
  2011年   224篇
  2010年   161篇
  2009年   114篇
  2008年   184篇
  2007年   217篇
  2006年   190篇
  2005年   200篇
  2004年   189篇
  2003年   175篇
  2002年   166篇
  2001年   182篇
  2000年   176篇
  1999年   141篇
  1998年   70篇
  1997年   64篇
  1996年   92篇
  1995年   73篇
  1994年   75篇
  1993年   58篇
  1992年   148篇
  1991年   132篇
  1990年   125篇
  1989年   147篇
  1988年   131篇
  1987年   129篇
  1986年   114篇
  1985年   122篇
  1984年   93篇
  1983年   67篇
  1982年   52篇
  1981年   36篇
  1980年   49篇
  1979年   80篇
  1978年   45篇
  1977年   50篇
  1976年   62篇
  1975年   46篇
  1972年   39篇
  1971年   40篇
排序方式: 共有5918条查询结果,搜索用时 15 毫秒
1.
The porcine circovirus type 2 (PCV2) is a swine infectious viral pathogen of great significance in global swine herds. It was recently detected at another Province of South Africa sequel to the first detection of North American‐like strain (PCV2a) at Gauteng about two decades ago, but there is a dearth of information about the genomic features and diversity of the viral strains in circulation within the country and the entire sub‐Saharan Africa region. To date, only one complete genome of the virus from South Africa is available on global data base. This current effort is therefore geared towards the full‐genome characterization of the circulating PCV2 strains in the pigs of Eastern Cape Province. With the use of conventional polymerase chain reaction method, fifteen complete PCV2 genomes were successfully amplified, sequenced and assembled from field samples obtained from non‐vaccinated pigs in the region. Neighbor Joining and Maximum Likelihood phylogenetic analyses of the ORF2 gene and full genomes unanimously showed that most of the assembled genomes (11) belong to genotype PCV2b. Furthermore, three of the characterized sequences formed clade with other reference mutant PCV2b and PCV2b subtype 1C (i.e. PCV2d) strains from the USA, China and South Korea. The last sequence, however, clustered with other reference strains belonging to PCV2 intermediate clade 2 (PCV2‐IM2), recently identified in a global PCV2 strains phylogenetic analysis. This study reports the first complete genome sequences of PCV2b, PCV2d and PCV2‐IM2 in pigs from South Africa, and it gives a possible insight into the genetic characteristics and variability of the viral strains presently in circulation within the country. It further emphasizes the need for more stringent measures in curtailing the introduction and spread of transboundary swine pathogens in the country and entire Southern African region.  相似文献   
2.
3.
4.
Thirty women, 25 with incontinence and five asymptomatic volunteer control subjects, were evaluated urodynamically by a variety of techniques, including ultrasound cystourethrography. The ultrasound evaluation was found to be a helpful adjunct in diagnosis. In comparison with radiologic techniques it offers more safety, more comfort, more privacy, more viewing time, and less cost. Bladder and urethral morphology during voiding activity and the amount and direction of urethrovesical mobility are easily determined by utilizing ultrasound techniques.  相似文献   
5.
Balloon dilatation of the very small ductus arteriosus is described, and its application in five patients undergoing catheter occlusion is presented and discussed.  相似文献   
6.

Background  

Pulmonary dysfunction following cardiac surgery is believed to be caused, at least in part, by a lung vascular injury and/or atelectasis following cardiopulmonary bypass (CPB) perfusion and collapse of non-ventilated lungs.  相似文献   
7.
The diagnosis of hysteria is often incorrect and must be made with great caution. A retrospective study demonstrates that an erroneous diagnosis of hysteria is most likely to be given to females, the psychiatrically ill, patients who embellish and patients who present plausible psychogenic explanations for their illness. Movement disorders and paralysis are the neurologic disorders most frequently mislabeled as hysteria.  相似文献   
8.
9.

Background  

Shoulder disorders are a common health problem in western societies. Several treatment protocols have been developed for the clinical management of persons with shoulder pain. However available evidence does not support any protocol as being superior over others. Systematic reviews provide some evidence that certain physical therapy interventions (i.e. supervised exercises and mobilisation) are effective in particular shoulder disorders (i.e. rotator cuff disorders, mixed shoulder disorders and adhesive capsulitis), but there is an ongoing need for high quality trials of physical therapy interventions. Usually, physical therapy consists of active exercises intended to strengthen the shoulder muscles as stabilizers of the glenohumeral joint or perform mobilisations to improve restricted mobility of the glenohumeral or adjacent joints (shoulder girdle). It is generally accepted that a-traumatic shoulder problems are the result of impingement of the subacromial structures, such as the bursa or rotator cuff tendons. Myofascial trigger points (MTrPs) in shoulder muscles may also lead to a complex of symptoms that are often seen in patients diagnosed with subacromial impingement or rotator cuff tendinopathy. Little is known about the treatment of MTrPs in patients with shoulder disorders.  相似文献   
10.
The objective of this study was to investigate the effect of fluoridated elastomeric ligatures on the microbiology of local dental plaque in vivo. This randomized, prospective, longitudinal, clinical trial had a split-mouth crossover design. The subjects were 30 patients at the beginning of their treatment with fixed orthodontic appliances in the orthodontic departments of the Liverpool and the Sheffield dental hospitals in the United Kingdom. The study consisted of 2 experimental periods of 6 weeks with a washout period between. Fluoridated elastomers were randomly allocated at the first visit to be placed around brackets on tooth numbers 12, 11, 33 or 22, 21, 43. Nonfluoridated elastomers were placed on the contralateral teeth. Standard nonantibacterial fluoridated toothpaste and mouthwash were supplied. After 6 weeks (visit 2), the elastomers were removed, placed in transport media, and plated on agar within 2 hours. Nonfluoridated elastomers were placed on all brackets for 1 visit to allow for a washout period. At visit 3, fluoridated elastomers were placed on the teeth contralateral to those that received them at visit 1. At visit 4, the procedures at visit 2 were repeated. Samples were collected on visits 2 and 4. A logistic regression was performed, with the presence or absence of streptococcal or anaerobic growth as the dependent variable. A mixed-effects analysis of variance was carried out with the percentage of streptococcal or anaerobic bacterial count as the dependent variable. The only significant independent variables were the subject variable (P =<.001) for the percentage of streptococcal and anaerobic bacterial count and the visit variable for the percentage of streptococcal count (P =<.001). The use of fluoridated or nonfluoridated elastomers was not significant for percentage of either streptococcal (P =.288) or anaerobic count (P =.230). Fluoridated elastomers are not effective at reducing local streptococcal or anaerobic bacterial growth after a clinically relevant time in the mouth.  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