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   295篇
  免费   18篇
  国内免费   2篇
耳鼻咽喉   1篇
儿科学   17篇
妇产科学   3篇
基础医学   29篇
口腔科学   9篇
临床医学   20篇
内科学   69篇
皮肤病学   13篇
神经病学   5篇
特种医学   63篇
外科学   18篇
综合类   27篇
预防医学   22篇
眼科学   1篇
药学   11篇
肿瘤学   7篇
  2022年   2篇
  2021年   2篇
  2020年   4篇
  2019年   4篇
  2018年   6篇
  2017年   3篇
  2016年   6篇
  2015年   1篇
  2014年   8篇
  2013年   8篇
  2012年   8篇
  2011年   10篇
  2010年   10篇
  2009年   12篇
  2008年   14篇
  2007年   10篇
  2006年   6篇
  2005年   10篇
  2004年   6篇
  2003年   3篇
  2002年   7篇
  2001年   3篇
  2000年   3篇
  1999年   4篇
  1998年   17篇
  1997年   23篇
  1996年   14篇
  1995年   11篇
  1994年   5篇
  1993年   8篇
  1992年   2篇
  1990年   2篇
  1989年   6篇
  1988年   6篇
  1987年   6篇
  1986年   6篇
  1985年   19篇
  1984年   8篇
  1983年   3篇
  1982年   6篇
  1981年   7篇
  1980年   5篇
  1979年   1篇
  1978年   3篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1949年   1篇
排序方式: 共有315条查询结果,搜索用时 15 毫秒
101.
Young maternal age during pregnancy is linked with adverse birth outcomes. This study examined the role of maternal nutritional status in the association between maternal age and small for gestational age (SGA) delivery and birth length. We used data from a birth cohort study in Ethiopia, involving women who were 15–24 years of age and their newborns. A mediation analysis was fitted in a sample of 1,422 mother infant dyads for whom data on birth length were available, and 777 dyads for whom gestational age and birth weight was measured. We used commands, medeff for the mediation analysis and medsens for sensitivity analysis in STATA 14. Maternal nutritional status, measured by mid‐upper arm circumference, mediated 21% of the association between maternal age and birth length and 14% of the association with SGA delivery. The average direct effect (ADE) of maternal age on birth length was (β = 0.45, 95% CI [0.17, 0.99]) and the average causal mediated effect (ACME) was (β = 0.12, 95% CI [0.02, 0.15]). We also found an ADE (β = 0.31, 95% CI [0.09, 0.47]) and an ACME of (β = 0.05, 95% CI [0.003, 0.205]) of maternal age on SGA delivery. The sensitivity analysis suggests an unmeasured confounder with a positive correlation of 0.15 and 0.20 between the mediator and the outcome could explain the observed ACME for birth length and SGA, respectively. We cannot make strong causal assertions as the findings suggest the mediator partly explained the total effect of maternal age on both outcomes.  相似文献   
102.
103.
Molecular analysis of cutaneous B- and T-cell lymphomas   总被引:3,自引:0,他引:3  
Among extranodal non-Hodgkin's lymphomas, primary cutaneous lymphomas (CLs) represent a consistent group of B- and T-cell malignancies. We investigated the arrangement of Ig and T-cell receptor (TCR) genes, together with the involvement of several oncogenes and the tumor- suppressor gene p53, in a panel of primary cutaneous B- and T-cell lymphomas (CBCLs and CTCLs). Southern blot analysis was performed to detect rearrangements of the Ig, c-myc, bcl-1, bcl-2, bcl-3, bcl-6, and the NFKB2/lyt-10 genes in 52 cases of CBCLs and of the TCR, bcl-3, and NFKB2/lyt-10 genes in 38 cases of CTCLs. tal-1 gene deletions were analyzed in CTCLs by means of polymerase chain reaction (PCR). p53 gene mutations were assayed using PCR, single-strand conformation polymorphism analysis, and direct DNA sequencing in CBCL and CTCL cases. Clonal rearrangements of Ig genes or oncogenes were found in 25 of the 52 CBCLs. In particular, we detected rearrangements of the bcl-1 locus (2 cases), the bcl-2 gene (2 cases), the NFKB2/lyt-10 gene (2 cases), and the bcl-6 gene (1 case); interestingly, 4 of these cases showed a germline arrangement of the Ig genes. Clonal rearrangements of TCR genes were detected in 37 of the 38 CTCLs. Rearrangements of the NFKB2/lyt-10 gene were present in 2 cases and tal-1 gene deletions in 3 CTCL cases; p53 gene mutations were detected in 1 CTCL case. Overall, our data indicate that (1) clonal rearrangement of Ig genes is frequently undetectable by means of Southern blot in CBCLs (60%); (2) genetic lesions are involved in a limited but significant fraction of primary CLs showing a molecular marker of clonality (13/62; 20%); and (3) rearrangements of the bcl-1, bcl-2, or bcl-6 loci, associated with specific subsets of nodal lymphoid neoplasias, are rarely observed in CBCLs. Moreover, our results suggest that tal-1 gene deletions may play a pathogenetic role in non-acute T-cell malignancies and that, in the context of lymphoid malignancies, CLs may represent a favorable target for the possible oncogenic potential of the NFKB2/lyt-10 gene.  相似文献   
104.
Two infants presenting with respiratory distress in the first 24 h of life are described. Both patients underwent extensive investigation before the diagnosis of surfactant protein B-deficiency was reached. Both children died within 2 months of birth. Parental consanguinity was known to be a feature in the first case, who proved to have a previously unrecognized mutation of the surfactant protein B gene. In the second case, a history of parental consanguinity was not sought from the Caucasian family, but was later volunteered by the parents themselves. Case 2 proved to have the "common" surfactant protein B-deficient genotype. The key to diagnosis is having a high index of suspicion in any term or near-term newborn with severe respiratory distress; parental consanguinity must be excluded. Surfactant protein B-deficiency can be readily diagnosed from bronchoalveolar lavage specimens; a simple, inexpensive procedure which is well tolerated in newborns.  相似文献   
105.
A prospective blinded study of 201 patients was performed to determine the relative sensitivities and specificities of excretory urography/linear tomography (EU/LT) and ultrasound (US) for the diagnosis of renal parenchymal masses. Computed tomography (CT) was used as a standard. EU/LT permitted detection of 10% of CT-confirmed masses (cystic or solid) less than 1 cm, 21% of lesions greater than or equal to 1 cm but less than 2 cm, 52% of lesions greater than or equal to 2 cm but less than 3 cm, and 85% of lesions 3 cm or more in diameter. US permitted detection of 26% of CT-confirmed lesions less than 1 cm, 60% of lesions greater than or equal to 1 cm but less than 2 cm, 82% of lesions greater than or equal to 2 cm but less than 3 cm, and 85% of lesions 3 cm or more in size. The results confirm the relative insensitivity of EU/LT for masses less than 3 cm in diameter and of US for masses less than 2 cm. Further, they suggest that CT may have a role not only in evaluation of cases in which the urographic or sonographic results are questionable or positive, but also in confirmation of apparently negative urographic findings when clinical suspicion of a lesion is high.  相似文献   
106.
107.
Serial magnetic resonance (MR) studies of the cervical bone marrow were performed in five patients undergoing bone marrow transplantation for chronic granulocytic leukemia and in four patients with aplastic anemia who were treated with antilymphocytic globulin. Findings were compared with those from a group of healthy volunteers. Chemical shift imaging techniques were used to exploit the presence of protons in fat and water in the red marrow. Characteristic changes were seen in aplastic anemia before treatment, but derivation of images representing fat and water fractions was necessary to distinguish leukemic marrow. Acute changes during the treatment of leukemia may reflect the effects of chemotherapy and radiation therapy, whereas changes in the chronic phase of both diseases may prove useful in predicting treatment outcome. MR studies are likely to be useful in the assessment and treatment of hematologic disorders.  相似文献   
108.
A total of 31 patients with 45 episodes of failing arteriovenous dialysis fistulas was studied. Fistula failure was usually due to venous and/or anastomotic stenosis, often in conjunction with thrombosis. Abnormalities were treated by percutaneous dilation and occasionally streptokinase infusion. Most complications and failures occurred either in patients with recently created fistulas or in those with multiple or long segment stenosis associated with thrombosis. Patients with a single nonobstructing stenosis were very successfully treated with percutaneous techniques, which are the treatment of choice for this condition.  相似文献   
109.
Ultrasonography of alcoholic liver disease with histological correlation   总被引:6,自引:0,他引:6  
In alcoholic liver disease (fatty infiltration, alcoholic cirrhosis), the liver is diffusely abnormal on ultrasound. Changes in size, dilatation of the hepatic veins, and ascites may also occur. The authors conducted a histological correlation of these abnormalities in 22 alcoholic patients and 16 controls, grading the changes on a scale of 0 to 4+ for fat, fibrosis, and necrosis and noting tumor whenever present. Ultrasound detected abnormality in 21 cases (sensitivity = 95%) and correctly identified 15 controls (specificity = 94%). Of the 5 tumors seen, 4 hepatomas were detected and biopsied and 1 metastatic squamous-cell carcinoma was missed. Applications of commercially available A-scan module are considered and its limitations discussed. With the exception of minimal change (1+ fat or fibrosis), ultrasound detected many of the pathological changes seen in alcoholic liver disease.  相似文献   
110.
Background: Polymerase chain reaction (PCR) is useful for rapid microbial detection in body fluids with low microbial load. It is easier to use universal or broad range primers for the amplification of conserved stretches of DNA common to all bacteria like 16S rRNA gene, followed by restriction fragment length polymorphism (RFLP) of PCR products.  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