全文获取类型
收费全文 | 14907篇 |
免费 | 1223篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 118篇 |
儿科学 | 609篇 |
妇产科学 | 341篇 |
基础医学 | 1853篇 |
口腔科学 | 235篇 |
临床医学 | 1669篇 |
内科学 | 2970篇 |
皮肤病学 | 457篇 |
神经病学 | 1365篇 |
特种医学 | 746篇 |
外科学 | 1872篇 |
综合类 | 358篇 |
一般理论 | 7篇 |
预防医学 | 1224篇 |
眼科学 | 262篇 |
药学 | 832篇 |
中国医学 | 4篇 |
肿瘤学 | 1293篇 |
出版年
2021年 | 168篇 |
2019年 | 184篇 |
2018年 | 221篇 |
2017年 | 160篇 |
2016年 | 182篇 |
2015年 | 201篇 |
2014年 | 280篇 |
2013年 | 429篇 |
2012年 | 566篇 |
2011年 | 634篇 |
2010年 | 340篇 |
2009年 | 358篇 |
2008年 | 591篇 |
2007年 | 626篇 |
2006年 | 582篇 |
2005年 | 627篇 |
2004年 | 559篇 |
2003年 | 512篇 |
2002年 | 509篇 |
2001年 | 488篇 |
2000年 | 515篇 |
1999年 | 447篇 |
1998年 | 260篇 |
1997年 | 221篇 |
1996年 | 181篇 |
1995年 | 175篇 |
1994年 | 164篇 |
1993年 | 147篇 |
1992年 | 368篇 |
1991年 | 359篇 |
1990年 | 379篇 |
1989年 | 387篇 |
1988年 | 287篇 |
1987年 | 335篇 |
1986年 | 326篇 |
1985年 | 329篇 |
1984年 | 223篇 |
1983年 | 245篇 |
1982年 | 143篇 |
1981年 | 112篇 |
1980年 | 123篇 |
1979年 | 208篇 |
1978年 | 155篇 |
1977年 | 142篇 |
1976年 | 158篇 |
1975年 | 146篇 |
1974年 | 144篇 |
1973年 | 136篇 |
1972年 | 107篇 |
1970年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Joseph G Rajendran Ajay K Gopal Darrel R Fisher Larry D Durack Ted A Gooley Oliver W Press 《Journal of nuclear medicine》2008,49(5):837-844
Myeloablative radioimmunotherapy using (131)I-tositumomab (anti-CD20) monoclonal antibodies is an effective therapy for B-cell non-Hodgkin's lymphoma. The amount of radioactivity for radioimmunotherapy may be determined by several methods, including those based on whole-body retention and on dose to a limiting normal organ. The goal of each approach is to deliver maximal myeloablative amounts of radioactivity within the tolerance of critical normal organs. METHODS: Records of 100 consecutive patients who underwent biodistribution and dosimetry evaluation after tracer infusion of (131)I-tositumomab before radioimmunotherapy were reviewed. We assessed organ and tissue activities over time by serial gamma-camera imaging to calculate radiation-absorbed doses. Organ volumes were determined from CT scans for organ-specific dosimetry. These dose estimates helped us to determine therapy on the basis of projected dose to the critical normal organ receiving a maximum tolerable radiation dose. We compared organ-specific dosimetry for treatment planning with the whole-body dose-assessment method by retrospectively analyzing the differences in projected organ-absorbed doses and their ratios. RESULTS: Mean organ doses per unit of administered activity (mGy/MBq) estimated by both methods were 0.33 for liver and 0.33 for lungs by the whole-body method and 1.52 for liver and 1.74 for lungs by the organ-specific method (P=0.0001). The median differences between methods were 0.92 mGy/MBq (range, 0.36-2.2 mGy/MBq) for lungs, 0.82 mGy/MBq (range, 0.28-1.67 mGy/MBq) for liver, and -0.01 mGy/MBq (range, -0.18-0.16 mGy/MBq) for whole body. The median ratios of the treatment activities based on limiting normal-organ dose were 5.12 (range, 2.33-10.01) for lungs, 4.14 (range, 2.16-6.67) for liver, and 0.94 (range, 0.79-1.22) for whole body. We found substantial differences between the dose estimated by the 2 methods for liver and lungs (P=0.0001). CONCLUSION: Dosimetry based on whole-body retention will underestimate the organ doses, and a preferable approach is to evaluate organ-specific doses by accounting for actual radionuclide biodistribution. Myeloablative treatments based on the latter approach allow administration of the maximum amount of radioactivity while minimizing toxicity. 相似文献
33.
Alfred E Buxton Hugh Calkins David J Callans John P DiMarco John D Fisher H Leon Greene David E Haines David L Hayes Paul A Heidenreich John M Miller Athena Poppas Eric N Prystowsky Mark H Schoenfeld Peter J Zimetbaum Paul A Heidenreich David C Goff Frederick L Grover David J Malenka Eric D Peterson Martha J Radford Rita F Redberg 《Journal of the American College of Cardiology》2006,48(11):2360-2396
34.
Daniel B. Costa Christopher A. Fisher Kenneth B. Miller German A. Pihan David P. Steensma Richard J. Gibbons Douglas R. Higgs 《European journal of haematology》2006,76(5):432-435
Abstract: We describe a patient with acquired alpha-thalassemia myelodysplastic syndrome (ATMDS). A previously healthy 66-year-old man presented with hemoglobin of 9.3 g/dL, mean corpuscular volume 59 fL, and a bone marrow aspirate with increased erythroid precursors and hypolobulated megakaryocytes. Hemoglobin H inclusions were seen in most red cells after 1% brilliant cresyl blue supravital stain of the peripheral blood. At the molecular level, we identified of a novel mutation in the most 3' exon of the ATRX gene ( C GA→ T GA substitution in codon 2407) resulting in a premature termination codon (p.R2407X). This case provides further evidence for a link between ATRX mutations and ATMDS, and suggests a possible role for the conserved Q-box element in ATRX function. 相似文献
35.
M. S. Levine A. M. Adinolfi R. S. Fisher C. D. Hull D. Guthrie N. A. Buchwald 《Brain research》1988,440(2):267-279
These studies provide information on the changes in the ultrastructure in the caudate nucleus of aged cats. The major findings was that there was a decrease in the density of synapses in caudate neuropil. This decrease occurred in animals after 3 years of age and remained relatively constant in older animals. In conjunction with this change a population of unusually long synapses also occurred. These larger synaptic appositions were associated with enlarged spine heads. The caudate also showed a number of qualitative ultrastructural alterations. Many neurons contained accumulations of lipofuscin or lipopigment granules in aged animals. These inclusions occurred in both soma and dendrites of neurons and all types of glial cells. A unique configuration of collapsed agranular cisterns also was observed in aged animals. The present results indicate that decreases in synaptic density may by one morphological event underlying functional alterations observed in caudate neurons in aged cats. 相似文献
36.
37.
38.
Background: The gastric bypass operation has evolved since 1966 when it was first introduced. The purpose of this study was
to determine the present state of gastric bypass by consensus among the members of the American Society for Bariatric Surgery
(ASBS). Method: A questionnaire was sent to all members of the ASBS. Forty-three percent responded reporting over 41,200 cases.
Results: Results were analyzed by using χ2 tests with a null hypothesis. Surgeons agreed on several technical aspects, preferring a vertical to a horizontal stapleline;
estimating, rather than measuring, the pouch volume at an average of 22 cc. Few surgeons divide the short gastric vessels,
and only 25% of surgeons polled use a restrictive ring or band proximal to the gastroenterostomy. Most surgeons calibrate
the gastroenterostomy, reporting a preferred average diameter of 12.3 cm. There was no consensus regarding forming the gastroenterostomy,
58% preferring hand-sewn and 42% stapled anastomoses. There was no consensus regarding dividing the gastric pouch from the
bypassed stomach: Conclusion: The preferred gastric bypass is vertical, with the pouch estimated at 20-25 cc, and the gastroenterostomy
calibrated at 12 mm diameter. The short gastric vessels need not be divided, and restrictive bands or rings are not preferred.
This technique of gastric bypass should be used as the control procedure when modifications are tested in future trials. Randomized
prospective studies are suggested to probe the benefits of division of the stomach pouch from the bypassed stomach. 相似文献
39.
Kay Fisher Neville A McBrien Kenneth J Ciuffreda 《Clinical & experimental optometry》1997,80(4):139-144
The influence of continuous variation in dioptric demand on the accommodative hysteresis induced at near distances was examined in 14 visually-normal young adults. Tonic accommodation was measured before and after 10 minutes of sustained focus using a constant stimulus at 5 D, 6.5 D, and 8 D, as well as a stimulus which slowly and alternately increased and decreased over the continuous range from 5 D to 8 D. For approximately half the subjects, dioptric demand had to be very high (8 D) under static conditions to produce moderate but significant hysteresis, yet little or no attenuation of the effect occurred under the dynamic condition. For other subjects who consistently showed very large tonic changes (1.4 D or more) under static conditions, the hysteresis effect generated under dynamic conditions was greatly reduced (approximately 50 per cent) in magnitude. These findings suggest that the degree to which continuous variation in dioptric demand will disrupt the adaptive process may depend on individual differences in the rate and/or maximum level of tonic accommodative change. Such a relationship could have bearing on the particular strategy recommended for individuals who tend to experience blur at distance following nearwork. 相似文献
40.
荧光原位杂交技术分析人结肠菌群方法研究 总被引:2,自引:0,他引:2
建立荧光原位杂交技术分析人体内结肠菌群的方法。取受试者新鲜粪便 ,选用 5种特异性的 16SrRNA寡核苷酸探针 ,检测粪便样本收集后的保存时间、温度 ,离心条件及样本固定液存放时间对杂交计数结果的影响。结果建立最佳实验条件为 :粪便样本收集后应尽快在 4℃下保存 ,放置时间不要超过 12小时即作处理 ;样本的适宜离心条件为 70 0g 2分钟 ;样本用多聚甲醛固定后在 - 80℃下存放时间不要超过 5个月。该方法具有较好的稳定性 ,可以有效地检出个体之间结肠菌群的差异。 相似文献