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   49758篇
  免费   4364篇
  国内免费   2357篇
耳鼻咽喉   640篇
儿科学   743篇
妇产科学   879篇
基础医学   4751篇
口腔科学   905篇
临床医学   6138篇
内科学   7460篇
皮肤病学   923篇
神经病学   2145篇
特种医学   1683篇
外国民族医学   17篇
外科学   4793篇
综合类   7915篇
现状与发展   9篇
一般理论   7篇
预防医学   4444篇
眼科学   977篇
药学   5164篇
  42篇
中国医学   3095篇
肿瘤学   3749篇
  2024年   99篇
  2023年   528篇
  2022年   1341篇
  2021年   1836篇
  2020年   1472篇
  2019年   1346篇
  2018年   1535篇
  2017年   1458篇
  2016年   1383篇
  2015年   2144篇
  2014年   2799篇
  2013年   3082篇
  2012年   4433篇
  2011年   4802篇
  2010年   3467篇
  2009年   2676篇
  2008年   3267篇
  2007年   2908篇
  2006年   2687篇
  2005年   2318篇
  2004年   1601篇
  2003年   1436篇
  2002年   1181篇
  2001年   951篇
  2000年   869篇
  1999年   752篇
  1998年   461篇
  1997年   418篇
  1996年   347篇
  1995年   309篇
  1994年   282篇
  1993年   205篇
  1992年   328篇
  1991年   287篇
  1990年   219篇
  1989年   174篇
  1988年   197篇
  1987年   162篇
  1986年   128篇
  1985年   124篇
  1984年   86篇
  1983年   46篇
  1982年   26篇
  1981年   37篇
  1980年   22篇
  1979年   32篇
  1978年   24篇
  1977年   21篇
  1975年   18篇
  1973年   24篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Vascular 18F-FDG uptake marker represents inflammation in atherosclerotic lesions, but whether inflammation can be reversed by risk-modifying interventions has not, to our knowledge, been demonstrated. In this study, we evaluated the change of vascular 18F-FDG uptake in response to lifestyle intervention on serial PET/CT scans and further assessed how the findings relate to atherogenic risk reduction. METHODS: A total of 60 healthy adults underwent 18F-FDG PET/CT scans and atherogenic risk-factor assessment at baseline and again after 17.1 +/- 8.3 mo of practicing lifestyle modification. The PET/CT images were evaluated for the presence of vascular 18F-FDG lesions, and vessel-to-blood-pool 18F-FDG ratios were measured. Indices from summed ratios of positive lesions were compared and correlated to atherogenic risk factors. RESULTS: At follow-up, significant reductions in diastolic blood pressure (P < 0.05), total cholesterol (P < 0.05), and low-density lipoprotein level (P < 0.05) and an increase in high-density lipoprotein (HDL) level (P < 0.0001) were demonstrated. On the initial PET/CT scan, 50 of 60 subjects showed 1 or more 18F-FDG-positive lesions (5.9 +/- 5.0/subject), leading to a total of 352 vascular sites. On follow-up, 18F-FDG-positive lesions were significantly reduced to 2.1 +/- 2.2 sites per subject (P < 0.0001) and a total of 124 sites (64.8% reduction). Follow-up 18F-FDG-positive rates were significantly reduced for the aorta and iliac arteries. In addition, significant reductions in the whole-body 18F-FDG index from 1.39 +/- 1.23 to 0.53 +/- 0.59 (P < 0.0001) and carotid 18F-FDG index from 0.08 +/- 0.16 to 0.03 +/- 0.06 (P = 0.01) were shown. The whole-body 18F-FDG index correlated with total cholesterol (P < 0.05) and HDL level (P < 0.05), and the magnitude of reduction in the 18F-FDG index closely correlated to the amount of increase in plasma HDL level (P = 0.005). CONCLUSION: Our study demonstrated that vascular 18F-FDG uptake is reversed in response to atherogenic risk reduction by lifestyle intervention and that the magnitude of improvement correlates to increases in plasma HDL levels. Thus, serial 18F-FDG PET/CT may be useful for monitoring improvements in the inflammatory component of atherosclerotic lesions in response to risk modification.  相似文献   
22.
"插入式"输尿管肠管吻合在原位肠道膀胱替代术中的应用   总被引:1,自引:0,他引:1  
目的 探讨"插入式"输尿管肠管吻合在原位肠道膀胱替代术中的手术效果和临床疗效.方法 对38例原位肠道膀胱替代术中75侧行"插入式"输尿管肠管吻合术患者进行随访,通过影像学、膀胱尿道镜、病理学、实验室检查等观察临床疗效.结果 术后平均随访(31.65±14.14)个月,吻合口狭窄率4%(3/75);抗返流率100%;无吻合口漏;膀胱尿道镜下,输尿管种植部位形成乳头,钳取7例患者乳头表面小块上皮组织作病理检查,其中乳头基底部2例为肠黏膜上皮,乳头尖端5例为移行上皮;所有患者复查肾功能均在正常范围,血Cr 54-135 μmol/L,BUN 3.2~9.4 mmol/L.结论 "插入式"输尿管肠管吻合术是一种较理想的输尿管肠管抗返流吻合术式.  相似文献   
23.
目的 探讨FK506-壳聚糖膜片与培养的雪旺细胞生物相容性.方法 将生长状况和纯度较好的第3代雪旺细胞,分别传代接种于含有FK506-壳聚糖膜片、单纯壳聚糖膜片的培养皿中培养,以盖玻片作为对照组.计算3组雪旺细胞倍增时间、雪旺细胞纯度;用MTT法比较不同膜片上雪旺细胞的生长活力,绘制生长曲线;S-100免疫荧光染色.结果 雪旺细胞倍增时间对照组为5.9 d,单纯壳聚糖膜片及FK506-壳聚糖膜片组均为4.0 d;雪旺细胞纯度分别为80%、89%,93%;雪旺细胞增殖情况以FK506-壳聚糖组最佳,单纯壳聚糖组次之,对照组最差;各组雪旺细胞均呈S-100阳性,FK506-壳聚糖组与单纯壳聚糖组雪旺细胞排列呈典型的漩涡状或栅栏状.结论 FK506-壳聚糖膜片具有更显著的组织相容性与生物功能性,并保持了雪旺细胞的生物学特性.  相似文献   
24.
GIEBEL系统在胫骨高位截骨术中的应用   总被引:4,自引:3,他引:1  
[目的]探讨GIEBEL内固定系统固定的胫骨高位截骨术治疗膝内翻畸形的效果。[方法]对19例31膝,平均53.5岁的膝内翻患者进行评价。术前内翻畸形平均12.29°;膝关节症状以内侧间室疼痛为主。不伴有其他关节间室病变。对患膝进行精确的胫骨高位截骨术后应用GIEBEL系统内固定截骨端。手术前后拍摄双下肢负重位全长X线片,测量内翻角、机械轴线和解剖轴线。记录内外侧关节间隙距离的差值以及关节活动度。同时进行Lysholm评分。术后对患者进行主观满意度调查。[结果]对19例患者平均随访22个月。术后1例腓总神经一过性麻痹,2例切口脂肪液化延迟愈合。截骨处至术后12~16周均骨性愈合。测量矫正角度平均12.32°。3例患者残留膝前疼痛和关节绞锁症状。在随访期间膝内外侧间隙无明显退变加重。手术效果优良率为89.5%。84.2%患者对手术效果表示满意。除膝关节活动度外,Lysholm评分、内外关节间隙差以及内翻角度在手术前后差异均有统计学显著性差异。[结论]GIEBEL系统可有效地固定胫骨高位截骨术截骨端,对轻中度膝关节内翻畸形患者固定强度大,骨愈合率高。  相似文献   
25.
Objective: The main aim of the present study was to examine the effectiveness and complication rate of the 1 cm right‐sided unilateral sublabial trans‐sphenoidal surgery for patients with pituitary adenoma equal to or greater than 5 mm in diameter. Method: A total of 350 patients were surgically treated for pituitary adenomas between December 1999 and December 2003 in an academic neurosurgical unit in China. Three hundred patients (86%) were treated with the 1‐cm right‐sided unilateral sublabial trans‐sphenoidal approach. The mean age of patients was 43 years (range 10–78 years) and female patients accounted for 59% of the total. One hundred and ninety‐six (64%) patients had functioning endocrine tumours and 104 (36%) patients had non‐functioning tumours or macroadenomas. Tumours which were outside this simple and basic classification were excluded from the study. Results: There were no operative mortalities. One patient developed hypopituitarism and 16 (5%) developed transient diabetes insipidus that required pituitrin treatment. The remission rate for macroadenoma was 85% and that for microadenoma was 98.5% during a medium term follow‐up of 1–5 years. One hundred and fifteen patients had prolactin secreting tumours and 90.4% achieved endocrine remission. Fifty‐six patients had growth hormone secreting tumours and 75.4% achieved endocrine remission. Preoperatively, one hundred and fifty‐one patients presented with visual impairment and 148 (98%) achieved a documented improvement in visual acuity. The mean duration of hospital stay was 4 days (range 3–7 days). Conclusion: This minimally invasive trans‐sphenoidal surgery for pituitary adenomas could be used as the primary treatment for small pituitary tumours. The effectiveness of the tumour removal and low morbidity rate compare favourably with the conventional sublabial approach as well as the more recently developed endoscopic endonasal approaches.  相似文献   
26.
目的:基于累及头颈部淋巴组织病变的临床不典型性,旨在探讨MRI对其进行鉴别诊断的客观依据。方法:对本组22例可疑累及头颈部淋巴组织的各类病变进行MRI检查并与病理学结果进行对照。结果:MRI对本组22例累及淋巴组织病变的诊断与病理学诊断的符合率(21/22)约为95%。结论:MRI是对累及头颈部淋巴组织病变的重要检查手段,并能为明确其诊断提供客观依据。  相似文献   
27.
A high incidence of bladder cancer has been documented in an area of chronic arsenic (As) exposure. This study investigates the characteristics of As-associated (n = 49) and other (n = 64) bladder cancers. A higher histological grading was observed for the As-exposed tumours (P = 0.04), but no other difference in pathobiological features or prognosis was found between the two groups.  相似文献   
28.
复方栀子冲剂栀子甙薄层扫描测定   总被引:11,自引:0,他引:11  
苏健  王宝琴 《中成药》1993,15(1):16-17
应用薄层扫描法测定了复方栀子冲剂中栀子甙的含量,对实验条件,以正交试验法进行优选,确定了最佳方案,排除了干扰,得到了满意的效果。  相似文献   
29.
1. The electrophysiological effects of dicentrine, an aporphine alkaloid isolated from the root of Lindera megaphylla, were examined in the Langendorff perfused rabbit heart and rabbit isolated cardiac cells. 2. Standard electrophysiological characters were measured in the Langendorff perfused rabbit heart (control study) and after 5 min exposure to 1, 3 and 9 microM of dicentrine and during the subsequent recovery phase sequentially (n = 7). The same study protocols were performed in 0.5 to 4.5 microM quinidine (n = 7), 18 to 162 microM procainamide and N-acetylprocainamide (n = 7) for comparison. 3. The results showed that the spontaneously beating heart rate and the sinoatrial (SA) and atrioventricular nodal (AH) conduction time were not significantly affected by dicentrine but were significantly suppressed by the higher doses of quinidine (4.5 microM) and procainamide (162 microM). 4. The His-Purkinje conduction time was significantly increased by the higher dose of dicentrine, quinidine and procainamide. 5. The ventricular repolarization time and its effective refractory period were significantly increased by the higher dose of dicentrine and the other agents. 6. The effective refractory period of the atrium, AV node and His-Purkinje system were also significantly increased by dicentrine and the other agents. 7. A voltage clamp study revealed that the prolongation of atrial action potential duration by dicentrine (9 microM) was associated with a significant inhibition of the transient potassium outward current. As well as inhibition of the transient outward current, a significant inhibition of the sodium inward current by dicentrine was found.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
30.
In this immunohistochemical study, the authors detected the expression of c-myc in keratinocytes (ECK) from 30 psoriatics before and after Qingdai Compound Capsule (QDCC) treatment and 12 normal subjects for control. The results showed that the ECK of patients before treatment was significantly higher than that in the normal control group, and its level was correlated with histopathological changes of affected skin. After treatment the ECK was normalized. It is believed that QDCC could decrease the ECK in psoriatics and this effect was probably mediated by inhibiting c-myc expression. This study provided an experimental evidence for the application of QDCC in treating psoriasis.  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