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   46930篇
  免费   2612篇
  国内免费   565篇
耳鼻咽喉   656篇
儿科学   1710篇
妇产科学   762篇
基础医学   5979篇
口腔科学   1044篇
临床医学   3483篇
内科学   11110篇
皮肤病学   1479篇
神经病学   3642篇
特种医学   1254篇
外国民族医学   2篇
外科学   6062篇
综合类   1307篇
一般理论   16篇
预防医学   3966篇
眼科学   1351篇
药学   3186篇
  6篇
中国医学   503篇
肿瘤学   2589篇
  2024年   58篇
  2023年   369篇
  2022年   501篇
  2021年   1378篇
  2020年   726篇
  2019年   1403篇
  2018年   2043篇
  2017年   1249篇
  2016年   1090篇
  2015年   1081篇
  2014年   1340篇
  2013年   2051篇
  2012年   3436篇
  2011年   3826篇
  2010年   1923篇
  2009年   1233篇
  2008年   2908篇
  2007年   3020篇
  2006年   2690篇
  2005年   2786篇
  2004年   2527篇
  2003年   2439篇
  2002年   2213篇
  2001年   1621篇
  2000年   1979篇
  1999年   1168篇
  1998年   355篇
  1997年   242篇
  1996年   242篇
  1995年   219篇
  1994年   145篇
  1993年   151篇
  1992年   212篇
  1991年   174篇
  1990年   154篇
  1989年   157篇
  1988年   140篇
  1987年   111篇
  1986年   96篇
  1985年   95篇
  1984年   85篇
  1983年   59篇
  1982年   44篇
  1981年   33篇
  1980年   38篇
  1979年   26篇
  1978年   29篇
  1977年   27篇
  1976年   23篇
  1973年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Carcinoma of the papilla of Vater is classified as periampullary cancer representing 5% of all gastrointestinal tract malignancies. Early and accurate diagnosis is important for those patients with a tumor of the papilla, as the prognosis is more favorable than in other periampullary neoplasms. Endoscopically obtained biopsies from suspicious papillae can detect an early tumor, although even for skilled pathologists it is often difficult to differentiate carcinomas from noninvasive lesions on the basis of forceps biopsies. The purpose of this study was to assess the preoperative diagnostic accuracy of duodenoscopy appearance and biopsy in all cases with suspicion of tumor. Thirty patients with suspicion of carcinoma of the papilla of Vater and with final diagnosis established by pancreatoduodenectomy were included in this retrospective study. In each case, a comparison was made between endoscopic biopsy and duodenoscopic appearance. Duodenoscopic appearance sensitivity and accuracy for malignancy were 86% and 83%, respectively, whereas endoscopic biopsy sensitivity and accuracy were 65% and 67%, respectively. Although preoperative diagnosis of carcinoma of the papilla of Vater is useful for making therapeutic decisions, the diagnostic value of the endoscopic appearance was superior to endoscopic biopsy in this series. Presented at the 2003 American Hepato-Pancreato-Biliary Association Congress, Miami, Florida, February 27-March 3, 2003. Supported by FADA-CAPES/PROP 200J (M.L.D.).  相似文献   
52.
53.
This paper presents a method of improving the TLD-100 dose reassessment performance. This method consists of applying numerical analysis techniques for evaluating the TLD-100 phototransferred thermoluminescence (PTTL) glow curve. From this analysis, a simple procedure for estimating the ultraviolet background components usually present in phototransferred thermoluminescence (TL) signals has been established. This procedure has been implemented in a computer program which performs the automatic evaluation of the glow curves and extracts the dose information contained in the PTTL curves. The use of this computer-aided evaluational method has enabled the extension of the working range of estimated absorbed dose down to 0.2-0.5 mGy with very adequate operational quality for doses even below the conventionally admitted lower reestimation limit (approximately 2 mGy). Because TL readout is a destructive process, the ability to reestimate doses can be important in any kind of dosimetric activity, such as operational dosimetry programs. The other commonly used dosimeter, film, uses a nondestructive readout and, therefore, presents some advantages over TLD when dose reassessment is necessary. With the reported improvements in the TLD-100 dose reassessment performance, the full range of absorbed doses covered by film dosimetry can now be reliably reassessed using TLD-100 dosimeters.  相似文献   
54.
55.
Summary We have studied the characteristics of arthritis present in 32 patients with Behçet's disease (BD), and how this arthritis is related to the HLA markers class I. 84% of the patients presented arthritis, the most common being monoarthritis as the initial presentation, and oligoarthritis in subsequent episodes. In 63% of the cases, the development was in episodes of acute/subacute arthritis. We found statistically significant association between antigens B-5 and B-51, and the group with BD, with a relative risk of 3.89 and 4.71 respectively. The attempt to relate markers B-5, B-51 and B-27 to the presence of arthritis as well as to its manifestation and further development was not conclusive.  相似文献   
56.
目的研究可控性丝线的致栓效果及其治疗体表难治性海绵状静脉畸形的初步疗效。方法将丝线一端留置于不同管腔大小的静脉内,另一端挂于血管壁埋于皮下,实现其可控性,用经过不同处置的丝线,分别留置于兔耳缘静脉、股静脉,观察其引起血管栓塞的效果。选择致栓效果较好的丝线组,用于临床治疗难治性体表海绵状静脉畸形的患者。结果几种经不同处置的丝线,均能不同程度地起到闭塞血管的作用,对于管腔稍大,血流较快的静脉(兔股静脉),浸泡丝裂霉素并打结的丝线组,致栓效果最好;临床初步应用证实,可控性丝线治疗体表难治性静脉畸形,安全有效。结论可控性丝线静脉内留置术,是一种安全、有效、损伤小、操作简便的治疗体表难治性海绵状静脉畸形的新方法。  相似文献   
57.
BACKGROUND AND PURPOSE: In intensity modulated radiotherapy (IMRT), the complexity and the number of treatment fields have expanded. This may imply that the delivery time for each fraction becomes prolonged. In a number of IMRT techniques used in the clinic, the delivery time per fraction is usually 10-15 min, sometimes more than 15 min. In studies on human skin, prolonged delivery time is shown to cause significant reduction of radiation effects compared with acute irradiation. In this paper the effect of changes in fraction delivery time was studied by in vitro irradiation of mammalian cells. MATERIAL AND METHODS: Chinese hamster fibroblasts (V79-379-A) were used for simulating clinical situations. Most experiments were performed with 2Gy/fraction with 4-h intervals in 40-60 replicates. Each fraction was divided into different subfractions, simulating the delivery of a complicated treatment. The effect of changing the delivery time for each fraction was studied. Parameters for the cell survival curve and repair kinetics were determined experimentally. The same methods were also used for large fraction sizes (8Gy). The validity of the most widely used models in the literature, all derived from linear-quadratic formalism, were tested against the experimental results. RESULTS: The effect of prolonging the fraction time for 2-Gy fractions was underestimated by the biological models. The experiments showed that 10-min prolonged delivery time gave a ratio between surviving fractions at 2Gy (S-ratio) of 1.054 with a 95% confidence interval (CI) 1.030-1.080, while the models predicted 1.007 and 1.009. Extending the fraction time to 20 min gave an S-ratio of 1.063 with CI of 1.045-1.080, while the models predicted 1.012 and 1.014. For 8-Gy fractions, there was a good agreement between predications and experimental results. The ratio between surviving fractions at 8Gy is 1.370 with CI of 1.300-1.440, while the models predicated 1.37 and 1.35. CONCLUSIONS: The effect of prolonging fraction time at conventional dose/fraction is underestimated by biological models. Prolonging the fraction time will spare tissues with a fast DNA repair. There is a risk for sparing tumours. This should be considered when IMRT technique is implemented in the clinic.  相似文献   
58.
Treatment of chronic osteomyelitis of distal tibia is complex. It often requires the association of antibiotic therapy and a surgical procedure. This consists of exhaustive debridement of infected bone and soft tissue which must have adequate cutaneous coverage and vascular supply which enables creating a barrier to microorganisms and greater resistance to infection. Free or pedicled muscular flaps have been the techniques most often used for this type of lesions. Free flaps require a precise microsurgical technique and prolonged surgery. Pedicled muscular flaps do not provide sufficient coverage and vascularisation of the distal tibia for large size defects. The fasciocutaneous flap has been used for the treatment of coverage defects in the perimalleolar area and the heel. We report the utility of this flap as management of chronic osteomyelitis of the distal third of the tibia with complete healing of the infection and correct cutaneous coverage without complications.  相似文献   
59.
60.
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