全文获取类型
收费全文 | 761篇 |
免费 | 122篇 |
国内免费 | 9篇 |
专业分类
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 |
出版年
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.
2.
Intratemporal vascular tumors: detection with CT and MR imaging 总被引:1,自引:0,他引:1
Lo WW; Shelton C; Waluch V; Solti-Bohman LG; Carberry JN; Brackmann DE; Wade CT 《Radiology》1989,171(2):445-448
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.
Suppiah Balachandran Stuart Eason Lynn McGuire Suzanne Bernard Charles Boyd 《European journal of nuclear medicine and molecular imaging》1986,12(2):69-71
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.
Goodman DA Eason RW Shiwai B Allinson N Magorrian B Grande M Ridgley A 《Journal of X-ray science and technology》1989,1(2):162-170
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.
Novel proteins with binding specificity for DNA CTG repeats and RNA CUG repeats: implications for myotonic dystrophy 总被引:7,自引:6,他引:7
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.
Ricardo Pietrobon Anand Shah Paul Kuo Matthew Harker Mariana McCready Christeen Butler Henrique Martins CT Moorman Danny O Jacobs 《BMC medical informatics and decision making》2006,6(1):32-11
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.
Dr. Linda K. Green MD Susan Zachariah MS CT David Y. Graham MD 《Digestive diseases and sciences》1990,35(11):1421-1425
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