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   4600篇
  免费   324篇
  国内免费   30篇
耳鼻咽喉   30篇
儿科学   167篇
妇产科学   170篇
基础医学   682篇
口腔科学   87篇
临床医学   584篇
内科学   922篇
皮肤病学   85篇
神经病学   543篇
特种医学   107篇
外科学   385篇
综合类   38篇
一般理论   4篇
预防医学   455篇
眼科学   65篇
药学   256篇
中国医学   2篇
肿瘤学   372篇
  2024年   9篇
  2023年   64篇
  2022年   129篇
  2021年   222篇
  2020年   154篇
  2019年   179篇
  2018年   177篇
  2017年   126篇
  2016年   167篇
  2015年   155篇
  2014年   202篇
  2013年   265篇
  2012年   376篇
  2011年   365篇
  2010年   195篇
  2009年   181篇
  2008年   279篇
  2007年   342篇
  2006年   282篇
  2005年   260篇
  2004年   202篇
  2003年   192篇
  2002年   171篇
  2001年   23篇
  2000年   15篇
  1999年   22篇
  1998年   31篇
  1997年   21篇
  1996年   17篇
  1995年   15篇
  1994年   9篇
  1993年   13篇
  1992年   4篇
  1991年   10篇
  1990年   11篇
  1989年   5篇
  1988年   8篇
  1987年   5篇
  1986年   5篇
  1985年   5篇
  1983年   4篇
  1981年   4篇
  1980年   3篇
  1979年   3篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1973年   3篇
  1972年   3篇
  1928年   2篇
排序方式: 共有4954条查询结果,搜索用时 15 毫秒
11.
Simian virus 40 (SV40) is a monkey virus that was administered to human populations by contaminated vaccines which were produced in SV40 naturally infected monkey cells.  相似文献   
12.
This study reports on the efficacy of a 'coma arousal procedure'. This procedure involved a programme of vigorous sensory stimulation administered to comatose patients by relatives using Comakits. An experimental group of 12 severely head-injured patients received the coma arousal procedure while a matched control group did not. Total duration of coma and weekly Glasgow Coma Scale Scores were recorded for the two groups. Results indicate that the total duration of coma was significantly shorter and that coma lightened more rapidly for the experimental group.  相似文献   
13.
Every child despite his individual differences and uniqueness is to be considered of equal worth. He should therefore be entitled to equal social, economic, civil and political rights, so that he may fully realise his inherent potential and share equally in life (Gill, 1979).

Obviously, these values are rooted in the humanistic philosophy of any nation's declaration of independence. In accordance with these value premises therefore “any act of commission or ommission by individuals, institutions or the society as a whole, and any conditions which deprive children of equal rights and liberties and interfere with their optimal development, constitutes by definition abuse or neglectful acts or conditions” (Gill, 1979).

Child abuse is a significant contemporary community problem. Although children have been maltreated throughout history, our community has been silent in defence of abused children. Child abuse is not a phenomenon of the 20th Century nor is it unique to our society and culture alone. It has occurred throughout the recorded history of man. The future of any nation depends on its children and their capabilities. For this reason, they must be given a full chance.  相似文献   
14.
OBJECTIVE: The purpose of this prospective study was to determine the positive predictive value (PPV) of the point of maximal posterior joint line tenderness (JLT), as a clinical sign, to diagnose underlying meniscal tears. METHODS: We conducted a prospective study of patients requiring arthroscopic surgery, who consecutively presented to the University of Calgary's Sport Medicine Centre. The femurotibial joint line was palpated for the point of maximal tenderness. We recorded the data on the arthroscopy report. A second examiner (orthopedic sport medicine surgical fellow or sport medicine physician) performed the same protocol. An arthroscopist documented the site of pathology as detected by arthroscopy. RESULTS: We found a PPV of 60.0% and a negative predictive value of 62.5%, suggesting that maximal posterior JLT may be predictive of meniscal pathology. The sensitivity and specificity were 84.6% and 31.2%, respectively (p = 0.155), with Fisher's exact test. The kappa score assessed interobserver reliability and was good at 0.48. Patients with maximal posterior JLT but no meniscal pathology did have other confounding pathology and patients with no maximal posterior JLT who had meniscal pathology usually had confounding knee pathology. CONCLUSIONS: We found a PPV of 60.0% of maximal posterior JLT and meniscal pathology located at the same anatomical site on arthroscopic examination.  相似文献   
15.
16.
17.
18.
Haemophilia A: molecular insights.   总被引:1,自引:0,他引:1  
Haemophilia A is the most common inherited bleeding disorder caused by defects in the F8C gene that encodes coagulation factor VIII. This X-linked recessive disorder occurs in approximately 1:5000 males. Haemophilia A is diagnosed based on normal prothrombin time, altered activated partial thromboplastin time and reduced factor VIII activity in plasma. Carrier females are usually asymptomatic and can be identified only by molecular analysis. The most frequent mutations in F8C are intron 22 and 1 inversions, which occur in approximately 50% and 5% of patients, respectively, with a severe phenotype. Large gene deletions are observed in approximately 5% of alleles from patients with severe haemophilia A. The remaining severe cases and all moderate and mild cases result from numerous point mutations and small insertions/deletions, which are de novo mutations in one-third of cases. Thus, molecular diagnosis of carrier status and prenatal diagnosis in families without intron 22 or 1 inversions is based on scanning techniques or gene sequencing. When the disease-causing mutation cannot be identified, molecular diagnosis is performed by linkage analysis of several DNA polymorphic markers linked to F8C. Given the clinical heterogeneity among haemophilic patients, many groups, including our own, have examined the relationships between prothrombotic gene variants and haemophilic phenotype to investigate whether prothrombotic gene variants modify clinical expression of the disease.  相似文献   
19.
Expression of CDX2 and MUC2 in Barrett's mucosa   总被引:3,自引:0,他引:3  
Barrett's mucosa is a risk factor for esophageal adenocarcinoma and should be detected at an early stage. It is defined by the presence of columnar epithelium with goblet cells in the lower esophagus, but histologic diagnosis can be uncertain in the absence of distinct goblet cells. We investigated 55 biopsies from 48 patients with endoscopically plain Barrett's esophagus and performed immunohistochemistry for CDX2 and MUC2. In addition, alcian blue (pH 2,5)/PAS staining was done. In histologically unequivocal Barrett's mucosa, nuclear expression of CDX2 in goblet cells and many columnar cells, as well as cytoplasmic positivity for MUC2 in goblet cells, could be observed. Alcian blue (pH 2,5)/PAS stained acidic mucins in goblet cells and in some non-goblet columnar cells. In six cases, no definite Barrett's mucosa was present, and no expression of MUC2 could be observed. In these biopsies, there was granular cytoplasmic and/or focal nuclear staining for CDX2 in non-goblet columnar epithelial cells, indicating their intestinal differentiation. We suggest that this peculiar mucosa is the precursor of unequivocal Barrett's mucosa and would designate it early Barrett's mucosa. Alcian blue for acidic mucins is inconsistent in this epithelium and does not reliably indicate early intestinal differentiation.  相似文献   
20.
A 3D MRI sequence for computer assisted surgery of the lumbar spine   总被引:2,自引:0,他引:2  
The aim of this research was to develop a magnetic resonance (MR) sequence capable of producing images suitable for use with computer assisted surgery (CAS) of the lumbar spine. These images needed good tissue contrast between bone and soft tissue to allow for image segmentation and generation of a 3D-surface model of the bone for surface registration. A 3D double echo fast gradient echo sequence was designed. Images were filtered for noise and non-uniformity and combined into a single data set. Registration experiments were carried out to directly compare segmentation of MR and computed tomography (CT) images using a physical model of a spine. These experiments showed the MR data produced adequate surface registration in 90% of the experiments compared to 100% with CT data. The MR images acquired using the sequence and processing described in this article are suitable to be used with CAS of the spine.  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