全文获取类型
收费全文 | 979049篇 |
免费 | 81758篇 |
国内免费 | 9812篇 |
专业分类
耳鼻咽喉 | 13761篇 |
儿科学 | 26105篇 |
妇产科学 | 27303篇 |
基础医学 | 138011篇 |
口腔科学 | 27423篇 |
临床医学 | 90901篇 |
内科学 | 183167篇 |
皮肤病学 | 18319篇 |
神经病学 | 76406篇 |
特种医学 | 39256篇 |
外国民族医学 | 241篇 |
外科学 | 148293篇 |
综合类 | 43138篇 |
现状与发展 | 26篇 |
一般理论 | 268篇 |
预防医学 | 74075篇 |
眼科学 | 24056篇 |
药学 | 76852篇 |
114篇 | |
中国医学 | 7555篇 |
肿瘤学 | 55349篇 |
出版年
2021年 | 10746篇 |
2019年 | 9190篇 |
2018年 | 11324篇 |
2017年 | 9360篇 |
2016年 | 9871篇 |
2015年 | 12788篇 |
2014年 | 17424篇 |
2013年 | 22650篇 |
2012年 | 31274篇 |
2011年 | 33271篇 |
2010年 | 19636篇 |
2009年 | 17640篇 |
2008年 | 28805篇 |
2007年 | 30817篇 |
2006年 | 30748篇 |
2005年 | 30398篇 |
2004年 | 27941篇 |
2003年 | 26846篇 |
2002年 | 25303篇 |
2001年 | 38567篇 |
2000年 | 39342篇 |
1999年 | 33956篇 |
1998年 | 11334篇 |
1997年 | 10620篇 |
1996年 | 9994篇 |
1995年 | 9427篇 |
1994年 | 8947篇 |
1992年 | 27729篇 |
1991年 | 27057篇 |
1990年 | 26435篇 |
1989年 | 25401篇 |
1988年 | 23838篇 |
1987年 | 23429篇 |
1986年 | 22170篇 |
1985年 | 21482篇 |
1984年 | 16600篇 |
1983年 | 14142篇 |
1982年 | 8952篇 |
1979年 | 16835篇 |
1978年 | 12162篇 |
1977年 | 10210篇 |
1976年 | 9362篇 |
1975年 | 10190篇 |
1974年 | 12693篇 |
1973年 | 12171篇 |
1972年 | 11554篇 |
1971年 | 10706篇 |
1970年 | 10230篇 |
1969年 | 9922篇 |
1968年 | 8907篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Xin He Jonathan M. Links Karen L. Gilland Benjamin M. W. Tsui Eric C. Frey 《Journal of nuclear cardiology》2006,13(3):345-353
BACKGROUND: The optimal projection data acquisition strategy for myocardial perfusion (MP) single photon emission computed tomography (SPECT) remains controversial. METHODS: We compared MP SPECT using 180 degrees and 360 degrees projection data obtained with the same acquisition time, reconstructed either with filtered back projection (FBP) or the iterative ordered-subsets expectation maximization (OS-EM) algorithm with various combinations of attenuation, detector response, and scatter compensation using mathematical observers and a myocardial defect detection task. We used Monte Carlo-simulated projection data from a population of 3-dimensional nurbs-based cardiac-torso (NCAT) phantoms with ranges of variability in patient anatomy, organ uptake, defect location, defect size, and noise level based on clinical data. Projection data from 180 degrees and 360 degrees acquisitions were generated by assuming the same acquisition time. After iterative or FBP reconstruction, standard postprocessing methods were applied. For each acquisition and reconstruction method, we optimized the number of iterations and cut-off frequency of the Butterworth filter using the Channelized Hotelling Observer methodology. The optimum set of parameters was that which gave the maximum area under the curve. RESULTS: For both acquisition protocols, OS-EM with compensations provided better performance than FBP or OS-EM without compensation. For FBP, the optimized 180 degrees acquisition provided a statistically significant increase in AUC as compared with optimized 360 degrees acquisition. For OS-EM, the AUCs for 180 degrees were slightly larger than for 360 degrees acquisitions when comparing images reconstructed with the same compensations. However, the differences were smaller and not statistically significant. CONCLUSION: With optimized reconstruction and filtering parameters, 180 degrees acquisition provided a statistically significant improvement over 360 degrees acquisition for FBP reconstruction. However, for OS-EM the differences were small and not statistically significant. 相似文献
992.
IPEX (immunodysregulation, polyendocrinopathy, enteropathy, X linked syndrome) is a rare disorder which usually results in death in early infancy or childhood. Clinical awareness remains the cornerstone of diagnosis, and provided that the diagnosis is entertained, mutation analysis for FOXP3 gene mutations can be confirmatory. Two new patients in whom IPEX was diagnosed retrospectively are reported. 相似文献
993.
Martine C M Willems L W Ernest van Heurn Geert W Schurink Frank M van der Sande Jan H M Tordoir 《Nephrology, dialysis, transplantation》2006,21(12):3583-3584
994.
AIM: To report the treatment of a recurrent adenoid-cystic carcinoma of the lacrimal gland required orbital exenteration with an en bloc resection of the lateral orbital rim and wall and an anterior portion of the temporal muscle. Reconstruction was planned with both the objectives of a shortened healing time for faster epithetic reconstruction and no visible scars. METHOD: After a cranially extended temporal approach, the dissection of the superficial galea layer was connected with the subcutaneous dissection of the upper and lower eyelid after subciliary incisions. RESULTS: Ample exposure of the temporal, frontal and orbital region was obtained, facilitating the orbital exenteration with en bloc resection of the lateral orbital rim and wall and the anterior portion of the temporal muscle. The epithelialization of the eye socket covered with the galea fascia flap was accelerated, providing faster epithetic reconstruction, without visible scars. CONCLUSIONS: Healing time is accelerated, providing faster epithetic rehabilitation without visible scars, which is important in the postoperative rehabilitation ladder after eye exenteration for both patient and surgeon. Further more ablative surgery within this region gets safer and easier due to the ample exposure of this innovative surgical technique. Further evaluation of the effectiveness and safety of this new approach is advisable. 相似文献
995.
996.
997.
998.
999.
1000.