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   897篇
  免费   21篇
  国内免费   1篇
耳鼻咽喉   14篇
儿科学   30篇
妇产科学   38篇
基础医学   119篇
口腔科学   11篇
临床医学   79篇
内科学   191篇
皮肤病学   38篇
神经病学   74篇
特种医学   23篇
外科学   124篇
综合类   1篇
预防医学   36篇
眼科学   21篇
药学   29篇
肿瘤学   91篇
  2022年   1篇
  2019年   2篇
  2018年   1篇
  2016年   2篇
  2015年   7篇
  2014年   2篇
  2013年   5篇
  2012年   71篇
  2011年   76篇
  2010年   28篇
  2009年   17篇
  2008年   111篇
  2007年   117篇
  2006年   129篇
  2005年   113篇
  2004年   91篇
  2003年   69篇
  2002年   40篇
  2001年   5篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   8篇
  1996年   1篇
  1995年   3篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1989年   1篇
  1988年   1篇
  1984年   1篇
  1982年   1篇
  1979年   2篇
  1973年   2篇
  1971年   1篇
排序方式: 共有919条查询结果,搜索用时 525 毫秒
81.
82.
83.
OBJECTIVE: To investigate the contribution of volume contrast imaging (VCI) in assessing the fetal uterus in normally developed female fetuses. METHODS: The pelvis of 38 normal female fetuses was examined at 20-22 and 32-34 weeks' gestation using both conventional two-dimensional (2D) ultrasound and VCI on the same transverse or oblique longitudinal view of the fetal pelvis. Two experienced sonographers evaluated the ability of both techniques to image the fetal uterus. Results were compared by kappa index to evaluate the interobserver variability. RESULTS: A clear picture of the fetal uterus was obtained in 50% and 82-87% of the cases at 20-22 weeks' gestation and in 80-85% and 95-100% of the cases at 32-34 weeks' gestation using conventional 2D ultrasound and VCI, respectively. There was moderate to good agreement of uterus visualization between the two observers, with kappa values ranging from 0.43 to 0.65. The lower level of agreement was obtained for conventional 2D ultrasound during the second trimester. CONCLUSIONS: Our results suggest that VCI may be successfully applied to prenatal ultrasonography of the fetal pelvis anatomy. By enhancing the contrast between the intrapelvic organs, VCI provides a clearer picture of the fetal uterus.  相似文献   
84.
The bacterial lacZ gene encoding for beta-galactosidase (beta-gal) is a common reporter gene used in transgenic mice. Nonetheless, the absence of fluorigenic substrates usable in live animals greatly hampered the non-invasive follow-up of this reporter gene expression. We used far-red fluorescence for imaging beta-Gal expression in live cells in vitro or in vivo. The 9H-(1,3-dichloro-9,9-dimethylacridin- 2-one-7-yl) beta-D-galactopyranoside substrate was used to monitor beta-Gal expression as a reporter of tumor growth, or of the physiological levels of an endogenous gene or of gene transfer in lung. A quantitative evaluation of this method as well as a comparison of its sensitivity with Firefly Luciferase-based bioluminescence was also performed. In vivo measurements showed that 10(3) beta-Gal tumor cells located under the skin were detectable. In deeper organs like lung, as little as 5 ng of beta-Gal or Luciferase enzymes per mg of proteins were measured, confirming that both techniques reached similar sensibilities. Nonetheless, quantitative comparison of beta-Gal levels measured with far-red imaging or with a standardized enzymatic evaluation after killing revealed that the 2D-fluorescent reflectance imaging method is submitted to a color-dependent disparity of the organs and cannot supply quantitative measurements but that a simple correction can be applied.  相似文献   
85.
Weight loss, together with psychological and behavioural symptoms and problems of mobility, is one of the principal manifestations of Alzheimer's disease (AD). Weight loss may be associated with protein and energy malnutrition leading to severe complications (alteration of the immune system, muscular atrophy, loss of independence). Various explanations have been proposed such as atrophy of the mesial temporal cortex, biological disturbances, or feeding behaviours; however, none has been proven. Prevention of weight loss in AD is a major issue. It requires regular follow-up and must be an integral part of the care plan. The aim of this article is to review the present state of scientific knowledge on weight loss associated with AD. We will consider four points: the natural history of weight loss, its known etiological factors, its consequences and the various management options.  相似文献   
86.
When a high titre inhibitor develops in a patient with haemophilia, attempts are made to eradicate it through immune tolerance induction therapy (ITI) involving the frequent and regular administration of factor, usually for months to years. ITI is successful in only two thirds of patients prompting investigators to explore alternate regimens to use in haemophiliacs failing conventional ITI. Rituximab is an anti-CD20 monoclonal antibody, which has shown promise in the treatment of B-cell-mediated disorders. We developed a protocol for the use of rituximab in haemophilia A (HA) patients failing conventional ITI or in those haemophiliacs where the likelihood of success of conventional ITI is poor. Patients receive 375 mg m(-2) of intravenous rituximab weekly for 4 weeks followed by monthly (up to 5 months) until inhibitor disappearance and establishment of normal FVIII pharmacokinetics (recovery and half-life). Patients are concurrently placed on recombinant FVIII (100 U kg(-1) day(-1)). We have placed five haemophiliacs (four children with severe HA, and one adult with mild HA) on this protocol. In three patients (two with severe HA and one with mild HA) inhibitors disappeared although in neither severe haemophiliac did FVIII pharmacokinetics completely normalize. The fourth patient had a significant drop in inhibitor titres although not a complete disappearance of the inhibitor. All four of these patients ceased bleeding following rituximab. The fifth patient had no response to rituximab. This non-responding patient was not placed on concurrent FVIII. Our five cases suggest that rituximab may hold promise in the eradication of inhibitors. Prospective randomized studies are required to determine the value of this agent in inhibitor management.  相似文献   
87.
88.
We report a case of a 67-year-old woman with no significant past ocular history, who was referred for management of an unresponsive microbial keratitis resulting from trauma with a piece of clothing fabric 1 month previously in Portugal and worsening despite topical fortified antibiotics. On examination, visual acuity was limited to "light perception". Slit lamp examination revealed an 11×11mm full-thickness corneal infiltrate. Confocal images showed branching hyphae suggestive of a fungal infection. Fungal cultures of corneal scrapings revealed growth of Cylindrocarpon lichenicola, a saprophytic, filamentous fungus, which is an unusual cause of keratitis. Despite aggressive antifungal therapy with voriconazole and amphotericin B, she required penetrating keratoplasty for impending corneal perforation. Follow-up was uneventful, with no recurrence at 1 year. Fungal infections must be suspected in all corneal ulcers of traumatic etiology. Specific cultures and confocal microscopy must be performed early, so as to enable early treatment modification.  相似文献   
89.
To evaluate the impact of ex vivo expanded megakaryocyte (MK) progenitors on high-dose chemotherapy-induced thrombocytopenia, we conducted a phase II study in 10 patients with relapsed lymphoma. Two fractions of peripheral blood progenitor cells (PBPC) were cryopreserved, one with enough cells for at least 2 x 10(6) CD34+ cells/kg and a second obtained after CD34+ selection. Ten days before autologous stem cell transplantation, the CD34+ fraction was cultured with MGDF+SCF for 10 days. After BEAM (BCNU, cyclophosphamide, cytarabine, and melphalan) chemotherapy, patients were reinfused with standard PBPC and ex vivo expanded cells. No toxicity was observed after reinfusion. The mean fold expansion was 9.27 for nucleated cells, 2 for CD34+ cells, 676 for CD41+ cells, and 627 for CD61+ cells. The median date of platelet transfusion independence was day 8 (range: 7-12). All patients received at least one platelet transfusion. In conclusion, ex vivo expansion of MK progenitors was feasible and safe, but this procedure did not prevent BEAM-induced thrombocytopenia. Future studies will determine if expansion of higher numbers of CD34+ cells towards the MK-differentiation pathway will translate into a functional effect in terms of shortening of BEAM-induced thrombocytopenia.  相似文献   
90.
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