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   412篇
  免费   54篇
  国内免费   1篇
耳鼻咽喉   2篇
儿科学   26篇
妇产科学   5篇
基础医学   73篇
口腔科学   6篇
临床医学   43篇
内科学   94篇
皮肤病学   6篇
神经病学   31篇
特种医学   11篇
外国民族医学   1篇
外科学   60篇
综合类   5篇
预防医学   34篇
眼科学   4篇
药学   21篇
肿瘤学   45篇
  2023年   3篇
  2022年   3篇
  2021年   9篇
  2019年   10篇
  2018年   7篇
  2017年   6篇
  2016年   9篇
  2015年   5篇
  2014年   12篇
  2013年   13篇
  2012年   17篇
  2011年   20篇
  2010年   9篇
  2009年   16篇
  2008年   20篇
  2007年   17篇
  2006年   15篇
  2005年   17篇
  2004年   21篇
  2003年   20篇
  2002年   20篇
  2001年   15篇
  2000年   13篇
  1999年   13篇
  1998年   8篇
  1997年   3篇
  1996年   6篇
  1994年   3篇
  1992年   16篇
  1991年   9篇
  1990年   12篇
  1989年   10篇
  1988年   7篇
  1987年   13篇
  1986年   6篇
  1985年   4篇
  1984年   7篇
  1983年   5篇
  1982年   3篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1975年   2篇
  1974年   3篇
  1973年   4篇
  1972年   4篇
  1969年   3篇
  1968年   3篇
  1965年   2篇
  1938年   2篇
排序方式: 共有467条查询结果,搜索用时 15 毫秒
131.
Recent studies indicate that brain-derived neurotrophic factor (BDNF) may be implicated in the clinical action of antidepressant drugs. Repeated (2-3 weeks) administration of antidepressant drugs increases BDNF gene expression. The onset of this response as well as concomitant effects on the corresponding BDNF protein is however, unclear. The present study investigated the effects of acute and chronic administration of the selective serotonin reuptake inhibitor, fluoxetine (10mg/kg p.o.), upon regional rat brain levels of BDNF mRNA and protein expression. To improve the clinical significance of the study, fluoxetine was administered orally and mRNA and protein levels were determined ex vivo using the techniques of in situ hybridisation histochemistry and immunocytochemistry respectively. Direct measurement of BDNF protein was also carried out using enzyme-linked immunosorbent assay (ELISA). Four days of once daily oral administration of fluoxetine induced decreases in BDNF mRNA (hippocampus, medial habenular and paraventricular thalamic nuclei). Whilst 7 days of treatment showed a non-significant increase in BDNF mRNA, there were marked and region-specific increases following 14 days of treatment. BDNF protein levels remained unaltered until 21 days of fluoxetine treatment, when the numbers of BDNF immunoreactive cells were increased, reaching significance in the pyramidal cell layer of CA1 and CA3 regions of Ammon's horn (CA1 and CA3) but not in the other sub-regions of the hippocampus. Indicative of the highly regional change within the hippocampus, the ELISA method failed to demonstrate significant up-regulation at 21 days, measuring levels of BDNF protein in the whole hippocampus. In contrast to the detected time dependent and biphasic response of the BDNF gene, activity-regulated, cytoskeletal-associated protein (Arc) mRNA showed a gradual increase during the 14-day course of treatment. The results presented here show that BDNF is expressed differentially depending on length of fluoxetine administration, which could contribute in explaining the slow onset of antidepressant activity observed with selective serotonin reuptake inhibitors.  相似文献   
132.
Flow cytometry evaluation of cell-mediated cytotoxicity   总被引:1,自引:0,他引:1  
A novel flow cytometry method for the evaluation of cell-mediated cytotoxicity is described. This method uses flow cytometry analysis to distinguish target cells from effector cells by differences in volume and light scatter characteristics. Non-viable target cells, following their interaction with effector cells, are determined via propidium iodide (PI) dye exclusion and then expressed as a percentage of the total target cell population. This assay is suitable both for analysis of systems which allow recycling of cytotoxic effector cells (total cell cytotoxicity assays, TCCA), and of systems in which recycling does not occur (single cell cytotoxicity assays, SCCA). Natural killer (NK) cell-mediated cytotoxicity evaluated by flow cytometry is significantly correlated with the standard 51Cr release assay. Flow cytometry can also be used to evaluate the competitive inhibition that certain cell types exert on the cell-mediated killing of NK-sensitive targets. A prerequisite for this assay is that competitor cells and target cells are distinguishable through their volume and light scatter characteristics. Advantages and pitfalls of the flow cytometry method are discussed, in comparison with the 51Cr-release assay.  相似文献   
133.
Neuroblastomas are malignant tumors derived embryonically from the neural crest. Biological diagnosis relies on assay of urinary excretion of homovanillic acid (HVA), vanillylmandelic acid (VMA), and dopamine (DA). Spontaneous regression of these neoplasms has been reported by numerous investigators. The authors report the case of a child with neuroblastoma that illustrates the relationship between catecholamine metabolites and tumor maturation. At 1 month of age, this infant presented an adrenal neuroblastoma with multiple metastases (stage IV); the initial histological diagnosis based on examination of cutaneous metastases was neuroblastoma. At the age of 6 months, after chemotherapy, the primary tumor was resected; hepatic metastases were discovered at laparotomy. The histological diagnosis for all lesions was highly differentiated, mature ganglioneuroma-like tissue. The main biochemical abnormality at the time of diagnosis was an elevation in normetanephrine (NMN). HVA was only slightly increased but rose progressively during chemotherapy; it dropped back to normal levels after the sixth course. This case illustrates the potential benefits of separate assays of urinary methylated catecholamine metabolites for biochemical diagnosis and therapeutic management of neuroblastoma in addition to assays of HVA, VMA, and DA. Case findings suggest existence of a transformation process with maturation of the tumor involving enzymatic regulation and expression of MAO. © 1996 Wiley-Liss, Inc.  相似文献   
134.
An infected aneurysm of the thoracic aorta due to mycobacterium tuberculosis is an unusual entity for which the classical treatment is antituberculosis chemotherapy and open-chest surgery. Recent improvements in endovascular treatments have led to their proposed use for infected aneurysms in patients for whom open surgery poses too high a risk. We report on a 68-year-old man with a tuberculous aortic aneurysm who had been treated with an endoprosthesis and antituberculosis chemotherapy. His clinical and radiological follow-up was uneventful and led to the discontinuation of pharmacological treatment after 16 months. However, a recurrence of the infection led to a fatal aortic rupture 4 months after discontinuation of therapy.  相似文献   
135.
BackgroundThe ACGME mandates that residency programs provide training related to high value care (HVC). The purpose of this study was to explore HVC education in general surgery residency programs.MethodsAn electronic survey was distributed to general surgery residents in geographically diverse programs.ResultsThe response rate was 29% (181/619). Residents reported various HVC components in their curricula. Less than half felt HVC is very important for their future practice (44%) and only 15% felt confident they could lead a QI initiative in practice. Only 20% of residents reported participating in a root cause analysis and less than one-third of residents (30%) were frequently exposed to cost considerations.ConclusionFew residents feel prepared to lead quality improvement initiatives, have participated in patient safety processes, or are aware of patients’ costs of care. This underscores the need for improved scope and quality of HVC education and establishment of formal curricula.  相似文献   
136.
The multitude of caval filters now available and conflicting experimental and clinical findings indicate that no one model can be considered to be perfect. The principal drawbacks of conical endocaval filters, such as the Greenfield model, are the possibility of migration and tilting, often related to failure to open, or untimely ejection of the filter. In this study, we analyzed the geometrical aspects of these filters, leaving aside all concerns of biocompatibility and thrombogenicity, as well as the hemodynamic or clinical aspects. The goal was to determine an ideal geometrical model, with optimal filtration of clots and low risk of tilting.  相似文献   
137.
Records of 117 patients with eyelid tumors on file at the University of Alabama at Birmingham were reviewed. Basal cell carcinoma was the single most common tumor, followed by squamous cell carcinoma, cutaneous melanoma, meibomian gland carcinoma and sebaceous gland carcinoma. A high percentage of patients with eyelid tumors were found to have secondary skin and non-skin tumors (41 percent).  相似文献   
138.
139.
Cerebral mycotic or infective aneurysms are a rare complication of infectious illness, and such aneurysms of the intracavernous portion of the internal carotid artery are rare. They have been described as a consequence of cavernous sinus infection in an immunocompromised host, but not previously in a renal transplant recipient. We present such a case with serial MRI showing progression from arterial narrowing to aneurysm formation. Transcranial Doppler sonography of the middle cerebral artery showed distal asymptomatic embolisation from the aneurysm.  相似文献   
140.
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