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   761篇
  免费   122篇
  国内免费   9篇
耳鼻咽喉   6篇
儿科学   21篇
妇产科学   22篇
基础医学   98篇
口腔科学   7篇
临床医学   106篇
内科学   106篇
皮肤病学   15篇
神经病学   31篇
特种医学   136篇
外科学   68篇
综合类   48篇
预防医学   46篇
眼科学   3篇
药学   36篇
中国医学   2篇
肿瘤学   141篇
  2022年   6篇
  2021年   16篇
  2020年   13篇
  2019年   16篇
  2018年   32篇
  2017年   16篇
  2016年   25篇
  2015年   25篇
  2014年   28篇
  2013年   34篇
  2012年   23篇
  2011年   28篇
  2010年   28篇
  2009年   29篇
  2008年   25篇
  2007年   22篇
  2006年   18篇
  2005年   24篇
  2004年   34篇
  2003年   36篇
  2002年   42篇
  2001年   33篇
  2000年   22篇
  1999年   23篇
  1998年   36篇
  1997年   15篇
  1996年   17篇
  1995年   17篇
  1994年   18篇
  1993年   17篇
  1992年   15篇
  1991年   7篇
  1990年   8篇
  1989年   16篇
  1988年   16篇
  1987年   10篇
  1986年   18篇
  1985年   10篇
  1984年   6篇
  1983年   8篇
  1982年   9篇
  1981年   4篇
  1980年   4篇
  1979年   3篇
  1978年   7篇
  1977年   8篇
  1975年   3篇
  1970年   2篇
  1969年   3篇
  1967年   3篇
排序方式: 共有892条查询结果,搜索用时 15 毫秒
1.
李强  张昱苹  谢东 《海南医学》2002,13(3):18-20
目的:探讨高分辨率CT(HRCT)对颞部疾病的检查价值。方法:对43例颞部疾病患者行常规CT和高分辨率CT(HRCT)检查所获图像对比分析,并讨论HRCT的检查技术和图像后处理。结果:HRCT对病变的显示率及病变引起骨质破坏的程度,病变边缘,轮廓的显示均明显优于常规CT,尤其能清楚显示常规CT难以显示的中耳及内耳的细微结构,结论:高分辨率CT是颞部疾病的首选检查方法,使用高分辨率CT对颞部疾病的检查给临床提供更多,更准确的诊断信息。  相似文献   
2.
Intratemporal vascular tumors: detection with CT and MR imaging   总被引:1,自引:0,他引:1  
The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion.  相似文献   
3.
骨巨细胞瘤的MRI诊断价值   总被引:10,自引:0,他引:10  
目的探讨骨巨细胞瘤的MRI表现特点及其病理基础。资料与方法搜集经手术病理证实的12例骨巨细胞瘤患者资料,分析其MRI征象并与病理结果对照。结果T1WI上肿瘤实体表现为低、等信号,T2WI上为不均匀高信号,Gd-DTPA增强扫描呈中度到明显强化。此外,MRI还可显示肿瘤内坏死、出血、含铁血黄素沉着等。结论MRI能够提供比较全面的影像学信息,可提高对骨巨细胞瘤诊断的准确性。  相似文献   
4.
5.
Summary In order to measure ejection fractions (EFs) from nuclear ventriculograms, we devised a semi-automated edge-detection technique based on a combination of inverse Fourier analysis and second-derivative techniques. Initial clinical studies showed that, for the left ventricle, our method gives EF values statistically identical with those obtained using a conventional isocontour technique. For the right ventricle, however, the values obtained using the two methods were somewhat more at variance. Despite requiring a longer processing time, the results obtained with our method are reproducible because less operator intervention is necessary.  相似文献   
6.
The faculty maintain close contact with the resource persons and are aware of their interaction with students on a weekly basis. Faculty and resource persons exchange observations, assessments, suggestions and problems they have either anticipated or experienced. The resource persons report that as students gain from the experiences, so do they. In particular, resource persons state interactions with students have stimulated them to increase their own clinical inquiry. A head nurse, functioning as a resource person, recently told the members of the Nursing Curriculum Committee she wished she had had such a course seven years ago when she was a senior in the program (S. Collier, personal communication, October 1987). She further elaborated that the learning opportunities she sees students experiencing today would have been invaluable to her and her peers as they began their professional nursing careers. We, the authors, believe individual learning opportunities with nurse leaders as resource persons is a unique, invaluable experience for nursing leadership students. These interactions provide a variety of learning opportunities sufficient for undergraduate students to develop beginning leadership skills, while also narrowing the education-practice gap. These experiences enhance the students' orientation to "real-world" nursing leadership and management. Students recognize the uniqueness of this teaching-learning strategy and value the time spent with resource persons. They frequently report never dreaming "that such problems have to be dealt with." They agree that learning with resource persons provides an essential ingredient for reinforcing the theoretical concepts of nursing leadership and putting classroom lectures into action.  相似文献   
7.
A crystal spectrometer with a photodiode array (PDA) detector was tested for a range of x-ray energies between 1 and 2 keV. A laser-produced plasma has been used as an x-ray source and was generated by the high-power (Vulcan) glass laser system at the SERC Rutherford Appleton Laboratory, UK. The performance of the array was directly compared with the response of Kodak DEF x-ray film. In order to compare quantitatively the performances of the PDA and the film, detective quantum efficiency (DQE) considerations are presented for both devices. It is demonstrated that the PDA has a useful dynamic range which is approximately seven times greater than that of film, a peak DQE of approximately six times that of film, and a greatly superior low-signal performance. The operational characteristics of the PDA are discussed.  相似文献   
8.
While an unstable CTG triplet repeat expansion is responsible for myotonic dystrophy, the mechanism whereby this genetic defect induces the disease remains unknown. To detect proteins binding to CTG triplet repeats, we performed bandshift analysis using as probes double- stranded DNA fragments having CTG repeats [ds(CTG)6-10] and single- stranded oligonucleotides having CTG repeats ss(CTG)8 or RNA CUG triplet repeats (CUG)8. The source of protein was nuclear and cytoplasmic extracts of HeLa cells, fibroblasts and myotubes. Proteins binding to the double-stranded DNA repeat [ds(CTG)6-10], were inhibited by nonlabeled ds(CTG)6-10, but not by a non-specific DNA fragment (USF/AD-ML). Another protein binding to ssCTG probe and RNA CUG probe was inhibited by nonlabeled (CTG)8 and (CUG)8. Nonlabeled oligos with different triplet repeat sequences, ss(CAG)8 or ss(CGG)8, did not inhibit binding to the ss(CTG)8 probe. However, when labeled as probes, the (CAG)8 and (CGG)8 bound to proteins distinct from the CTG proteins and binding was inhibited by nonlabeled (CAG)8 or (CGG)8 respectively. The protein binding only to the RNA repeat (CUG)8 was inhibited by nonlabeled (CUG)8 but not by nonlabeled single- or double-stranded CTG repeats. Furthermore, the CUG-BP exhibited no binding to an RNA oligonucleotide of triplet repeats of the same length but having a different sequence, CGG. The CUG binding protein was localized to the cytoplasm, whereas dsDNA binding proteins were localized to the nuclear extract. Thus, several trinucleotide binding proteins exist and their specificity is determined by the triplet sequence. The novel protein, CUG-BP, is particularly interesting since it binds to triplet repeats known to be present in myotonin protein kinase mRNA which is responsible for myotonic dystrophy.   相似文献   
9.

Background  

Although regulatory compliance in academic research is enforced by law to ensure high quality and safety to participants, its implementation is frequently hindered by cost and logistical barriers. In order to decrease these barriers, we have developed a Web-based application, Duke Surgery Research Central (DSRC), to monitor and streamline the regulatory research process.  相似文献   
10.
Diagnosis of metastatic lesions to the stomach by salvage cytology   总被引:1,自引:0,他引:1  
Summary Secondary neoplasms of the stomach are rare and are often clinical and diagnostic problems. Three patients with bleeding volcano-like ulcers were diagnosed by combined endoscopic salvage cytology and surgical biopsy as having metastatic submucosal lesions from hematologic spread. The combination of endoscopic appearance, clinical findings, and tissue and cytologic examination can lead to the correct diagnosis. The results from these cases support the utility of this cytologic technique in combination with biopsy in this clinical setting.  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