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   344篇
  免费   20篇
  国内免费   66篇
耳鼻咽喉   2篇
儿科学   41篇
妇产科学   1篇
基础医学   34篇
口腔科学   25篇
临床医学   61篇
内科学   77篇
皮肤病学   1篇
神经病学   10篇
特种医学   96篇
外科学   12篇
综合类   17篇
预防医学   6篇
药学   35篇
中国医学   2篇
肿瘤学   10篇
  2022年   1篇
  2019年   2篇
  2018年   2篇
  2017年   4篇
  2016年   4篇
  2015年   2篇
  2014年   3篇
  2013年   5篇
  2012年   5篇
  2011年   4篇
  2010年   6篇
  2009年   10篇
  2008年   6篇
  2007年   35篇
  2006年   8篇
  2005年   6篇
  2004年   2篇
  2003年   6篇
  2002年   13篇
  2001年   15篇
  2000年   11篇
  1999年   9篇
  1998年   26篇
  1997年   26篇
  1996年   25篇
  1995年   18篇
  1994年   18篇
  1993年   10篇
  1992年   1篇
  1991年   3篇
  1990年   11篇
  1989年   15篇
  1988年   16篇
  1987年   12篇
  1986年   11篇
  1985年   16篇
  1984年   4篇
  1983年   7篇
  1982年   8篇
  1981年   8篇
  1980年   5篇
  1978年   7篇
  1977年   4篇
  1976年   5篇
  1975年   7篇
  1958年   1篇
  1957年   2篇
  1956年   2篇
  1955年   1篇
  1954年   2篇
排序方式: 共有430条查询结果,搜索用时 62 毫秒
91.
92.
A red cell additive solution (AS-005) containing ascorbate-2-phosphate (AsP) to maintain 2,3-diphosphoglycerate, plus adenine, phosphate, and mannitol to retain viability and reduce hemolysis, was evaluated by human clinical trials. A crossover design was used with another additive solution (Nutricel AS-3, Cutter Laboratories) serving as the control for each donor. Each additive solution was evaluated at 35 and 42 days of storage. There was no significant difference between the red cell viability of the two storage solutions at either time period. Split-bag, AS-005 in vitro studies at two temperatures (2.5 and 5.5 degrees C), both within the range of 1 to 6 degrees C approved by the American Association of Blood Banks and the Food and Drug Administration, resulted in dramatically different in vitro parameters, including a threefold difference in 2,3-diphosphoglycerate (2,3-DPG), a fivefold difference in glucose, and significant differences in pH and adenosine triphosphate. High-pressure liquid chromatography data confirmed the preliminary report that 1 to 2 percent (wt/wt) oxalate was present in preparations of AsP. In vitro storage data confirmed that oxalate is the active component of AsP that preserves 2,3-DPG during storage.  相似文献   
93.
小藤铃儿草的生物碱成分   总被引:1,自引:0,他引:1  
自小藤铃儿草Dactylicapnos torulosa(Hook.f ct Thomas.)Hutchins中分得六个单体,通过UV,IR,MS,~1HNMR和~(13)CNMR解析,鉴定了四个,其中一个为新化合物,命名为紫金龙碱(zijinlongine,Ⅰ),其他三个为已知化合物:氯化1-甲氧基小檗碱(1-methoxylberberium chloride,Ⅱ),氯化三乙基苯胺(triethylphcnylamium chloride,Ⅲ)和异紫堇定(isocorydine,Ⅳ)。Ⅱ和Ⅲ系首次从植物中得到。  相似文献   
94.
A family showing inheritance of the Inab phenotype   总被引:2,自引:0,他引:2  
An 86-year-old white American woman was found to have a very rare red cell phenotype, the Inab phenotype. Her cells were Cr(a-), Tc(a-b-c-), Dr(a-), Es(a-), WES(a-b-), and IFC-. Unlike the two other Inab phenotype patients, she has no history of protein-losing enteropathy or any similar intestinal disorder. One of her four siblings also has the Inab phenotype, providing the first evidence that this phenotype may be inherited. Serum inhibitions showed that anit-Cra, -TCa, -Dra, -WESb, and -IFC are partially inhibited by sera from three siblings with the common red cell phenotype but not by serum from the Inab phenotype sibling. The serum of the proposita contained an antibody to a high-frequency antigen that showed characteristics of being a Cromer-related antibody.  相似文献   
95.
Hemimegalencephaly: MR imaging in five children   总被引:5,自引:0,他引:5  
Hemimegalencephaly is a rare brain malformation characterized by cerebral asymmetry and cortical dysplasia. Infants with the condition present with early seizures and severe encephalopathy. Five patients were studied with computed tomography and magnetic resonance (MR) imaging. MR imaging was the most efficient diagnostic method for this rare entity. It demonstrated brain hemispheric hypertrophy with lateral ventricle dilatation, abnormal gyral pattern, and a thick cortex on the enlarged side. The images correlate well with the known pathologic data.  相似文献   
96.
Middleton  WD; Melson  GL 《Radiology》1989,173(2):427-429
To determine the appearance of artifactual renal duplication in ultrasound (US) imaging, the authors analyzed 22 examples of such duplication in 20 patients. The artifact appeared as a duplication of the collecting system in 18, as a suprarenal mass in three, and as upper-pole cortical thickening in one. It occurred in the left kidney in 15 patients, in the right kidney in three, and bilaterally in two. To determine the frequency of the artifact, 50 additional patients were scanned. It was identified in eight of these patients. Imaging characteristics and the results of in vitro modeling proved the artifact was due to sound beam refraction between the lower pole of the spleen or liver and adjacent fat. This artifact is much more common in the left kidney and occurs more frequently in obese patients. Knowledge of the appearance and cause of this artifact should help radiologists avoid diagnostic errors.  相似文献   
97.
细胞周期素依赖激酶4在颌骨软骨肉瘤的表达及意义   总被引:3,自引:2,他引:1  
目的:分析细胞周期素依赖激酶4(CDK4)在颌骨软骨肉瘤的表达及意义。方法利用免疫组化法检测CDK4在20例颌骨软骨肉瘤、8例骨软骨瘤和8例骨质增生中的表达。结果65.0%(13/20)的软骨肉瘤中CDK4呈阳性表达CDK4表达率随病理学分级的升高呈增高趋势,但未见统计学差异(P〉0.05);CDK4在骨软骨瘤和骨质增生中的阳性表达率分别为12.5%(1/8)和0(0/8),且均与软骨肉瘤有显性  相似文献   
98.
99.
100.
Magnetic resonance (MR) imaging and computed tomography (CT) were compared in a prospective study of 48 patients for the detection of metastatic mediastinal lymphadenopathy from bronchogenic carcinoma. The images were interpreted by three experienced radiologists using a five-point rating scale, enabling receiver operating characteristic (ROC) analysis. Imaging results were evaluated against "truth" data based on analysis of surgical specimens from mediastinoscopy and thoracotomy. All MR images were cardiac gated to reduce cardiac motion artifacts in the mediastinum. MR and CT both performed well, as indicated by similar areas under the ROC curves of 0.779 +/- 0.039 for MR imaging and 0.781 +/- 0.038 for CT scanning. No strong correlation between nodal size and metastatic involvement could be found for either MR or CT results. As long as nodal size remains the sole criterion in the detection of metastatic mediastinal lymphadenopathy, MR imaging is unlikely to enable better interpretations than CT scanning.  相似文献   
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