全文获取类型
收费全文 | 48946篇 |
免费 | 3185篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 524篇 |
儿科学 | 1235篇 |
妇产科学 | 858篇 |
基础医学 | 6395篇 |
口腔科学 | 1252篇 |
临床医学 | 4751篇 |
内科学 | 9949篇 |
皮肤病学 | 725篇 |
神经病学 | 4778篇 |
特种医学 | 2551篇 |
外国民族医学 | 6篇 |
外科学 | 7227篇 |
综合类 | 592篇 |
一般理论 | 40篇 |
预防医学 | 4018篇 |
眼科学 | 1199篇 |
药学 | 2925篇 |
中国医学 | 69篇 |
肿瘤学 | 3225篇 |
出版年
2023年 | 206篇 |
2022年 | 348篇 |
2021年 | 807篇 |
2020年 | 612篇 |
2019年 | 810篇 |
2018年 | 951篇 |
2017年 | 773篇 |
2016年 | 914篇 |
2015年 | 1050篇 |
2014年 | 1468篇 |
2013年 | 2043篇 |
2012年 | 3102篇 |
2011年 | 3285篇 |
2010年 | 1866篇 |
2009年 | 1708篇 |
2008年 | 3054篇 |
2007年 | 3146篇 |
2006年 | 3104篇 |
2005年 | 3037篇 |
2004年 | 2843篇 |
2003年 | 2758篇 |
2002年 | 2655篇 |
2001年 | 619篇 |
2000年 | 573篇 |
1999年 | 637篇 |
1998年 | 601篇 |
1997年 | 468篇 |
1996年 | 421篇 |
1995年 | 403篇 |
1994年 | 322篇 |
1993年 | 292篇 |
1992年 | 371篇 |
1991年 | 338篇 |
1990年 | 308篇 |
1989年 | 325篇 |
1988年 | 292篇 |
1987年 | 309篇 |
1986年 | 279篇 |
1985年 | 300篇 |
1984年 | 305篇 |
1983年 | 292篇 |
1982年 | 318篇 |
1981年 | 297篇 |
1980年 | 263篇 |
1979年 | 225篇 |
1978年 | 233篇 |
1977年 | 195篇 |
1976年 | 168篇 |
1975年 | 177篇 |
1974年 | 183篇 |
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
71.
72.
Frank Makowiec Stefan Post Hans-Detlev Saeger Norbert Senninger Heinz Becker Michael Betzler Heinz J. Buhr Ulrich T. Hopt German Advanced Surgical Treatment Study Group 《Journal of gastrointestinal surgery》2005,9(8):1080-1087
Despite decreasing mortality rates, morbidity is still high after pancreatic head resection. Comparative data in the United
States and Europe show a relationship between hospital volume and mortality. Treatment strategies vary frequently, partially
because of the lack of evidence-based data. We performed a multi-institutional analysis in Germany evaluating current numbers,
indications, techniques, and complication rates of pancreatic head resection. Questionnaires were completed by seven high-volume
surgical departments regarding quantitative and qualitative aspects of pancreatic head resections in the period from 1999
to 2004 (five prospective and two retrospective institutional databases). A total of 1454 pancreatic head resections (944
for malignancy) were reported. Mean annual hospital volume ranged from 14 to 52 (10 to 43 in malignancy). Mortality was between
1.1% and 4.8%, morbidity was between 24% and 46%, and pancreatic leakage was between 9% and 20%. In malignant disease, all
centers perform standard lymphadenectomy and regard arterial infiltration as a contraindication for resection. However, the
rate of portal vein resection varied from 0% to 28%. No consensus is seen on the type of surgery for malignancy and chronic
pancreatitis. After resection for pancreatic cancer less than one fourth of the patients receive adjuvant therapy. The results
of our analysis in Germany confirm that pancreatic head resection can be performed with low mortality in specialized units.
Variations in indications, operative technique, and perioperative care may demonstrate the lack of evidence-based data and/or
personal and institutional experience. The low number of patients receiving adjuvant therapy after resection of pancreatic
cancer suggests that more efforts must be made to establish novel adjuvant therapies under randomized study conditions.
Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18,
2005 (oral presentation). 相似文献
73.
Attenuation correction in myocardial perfusion SPECT/CT: effects of misregistration and value of reregistration. 总被引:2,自引:0,他引:2
Sibyll Goetze Tracy L Brown William C Lavely Zhe Zhang Frank M Bengel 《Journal of nuclear medicine》2007,48(7):1090-1095
The accuracy of myocardial perfusion SPECT improves with attenuation correction. Algorithms for attenuation correction in hybrid SPECT/CT systems have the potential for misregistration of emission and transmission scans because CT and SPECT are obtained sequentially. Misregistration will influence regional tracer distribution and may reduce diagnostic accuracy. This study focused on the role of misregistration in cardiac SPECT/CT and the performance of a software-based approach for reregistration. METHODS: We included 105 consecutive patients who underwent clinical myocardial perfusion imaging on a SPECT/CT system. Images were quantitatively assessed for misregistration using fusion software. Results were recorded in millimeters in the x-, y-, and z-axes. Regional tracer uptake in 6 segments (anterior, septal, inferior, lateral, anteroapical, and inferoapical) for noncorrected and attenuation-corrected images before and after reregistration was obtained from polar maps. To determine the relative influence of misregistration, we correlated individual differences between noncorrected and attenuation-corrected images, as well as between attenuation-corrected images before and after reregistration, with the degree of misregistration in a multivariate analysis including additional clinical variables such as sex and body weight. RESULTS: The difference in regional radiotracer uptake was significant between noncorrected and attenuation-corrected images in all 6 segments and was most pronounced in the inferior wall. On multivariate analysis, misregistration contributed significantly to changes in radiotracer distribution in the anterior (P = 0.038), septal (P = 0.011), and inferior (P = 0.006) segments. The mean misregistration was 8.6 +/- 3.8 mm (1.25 +/- 0.55 pixel). Misregistration of one or more pixels was observed in 64% of studies. Reregistration of misalignment significantly affected regional radiotracer distribution in the segments shown to be influenced by misregistration. CONCLUSION: Misregistration occurs with SPECT/CT systems and influences regional tracer distribution on attenuation-corrected myocardial images. Reregistration of misaligned studies may be a useful tool for correction. The impact of this strategy on the diagnostic and prognostic accuracy of cardiac hybrid imaging needs to be determined. 相似文献
74.
Klaus-Dietrich Wolff Sami Swaid Dirk Nolte Roland A B?ckmann Frank H?lzle Christian Müller-Mai 《Journal of cranio-maxillo-facial surgery》2004,32(2):71-79
BACKGROUND: A carbonated apatite cement (NORIAN SRS) was used as a bone mineral substitute for the calvaria or viscerocranium in 27 patients. It has the consistency of a paste and hardens at physiologic pH and body temperature due to dahllite crystallization, which has the stoichiometric formula Ca(8.8)(HPO(4))(0.7)(PO(4))(4.5)(CO(3))(0.7)(OH)(1.3). MATERIAL AND METHODS: The cement was used for posttraumatic bone defects in the orbital, periorbital or malar regions (nine patients), posttraumatic deformities of the frontal bone (six patients), tumour-dependent bony defects of the calvaria (two patients) and posttraumatic or cystic defects of the mandible (five patients). In another five patients, the material was used to augment the atrophic anterior mandible in combination with the insertion of dental implants. Follow-up varied between 6 and 40 months (mean: 29 months). RESULTS: There was no inflammatory reaction surrounding the implanted material. There was no sign of infection in any of the patients and only one case of partial wound dehiscence with superficially exposed material. The defect fillings and augmentations were successful in all patients. None of the 19 dental implants which were inserted in combination with the material showed any sign of infection or loosening. Also, there was no loosening of the implants after loading (mean follow-up: 15 months). From the check-up radiographs, the material could be seen as a dense, radio-opaque structure. There were no material fractures or dislocations. Radiologically, the material seemed to be completely replaced by bony tissue after 30 months. CONCLUSION: Our 5-year clinical experience suggests that the material is a suitable bone mineral substitute for cranio-maxillofacial surgery especially for moderate-sized defects of the calvaria and forehead bone. It has advantages over preformed, solid bone substitute materials, and, due to its initial plasticity and eventual great compressive strength, it can also stabilize dental endosseous implants in the atrophic mandible. 相似文献
75.
Dear Professor Lian-Sheng Ma Professor Michael Hobsley I have greatly enjoyed reading the account of all you have done towards the development of "The World Journal of Gastroenterology" as described in the article by Zhen-Xi Li in the November st. Issue of the Journal.…… 《World journal of gastroenterology : WJG》2007,13(1):158-158
Dear Professor Lian-Sheng Ma,
Professor Michael Hobsley and I have greatly enjoyed reading the account of all you have done towards the development of "The World Journal of Gastroenterology", as described in the article by Zhen-Xi Li in the November 21st. Issue of the Journal. 相似文献
76.
77.
The prevalence of adult smoking in the United States declined from 42.4% in 1965 to 20.9% in 2005. Much of the success in
reducing the prevalence of adult smoking over the past four decades can be attributed to tobacco control policies. This paper
provides an overview of public health initiatives for smoking cessation in the United States and provides a review of the
existing literature on the effects of these tobacco control initiatives on adult smoking cessation. 相似文献
78.
79.