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   25817篇
  免费   2134篇
  国内免费   497篇
耳鼻咽喉   163篇
儿科学   1564篇
妇产科学   543篇
基础医学   1063篇
口腔科学   329篇
临床医学   2955篇
内科学   2788篇
皮肤病学   129篇
神经病学   1149篇
特种医学   437篇
外科学   2383篇
综合类   3862篇
现状与发展   1篇
一般理论   1篇
预防医学   7328篇
眼科学   180篇
药学   1874篇
  22篇
中国医学   414篇
肿瘤学   1263篇
  2024年   20篇
  2023年   499篇
  2022年   788篇
  2021年   1636篇
  2020年   1302篇
  2019年   1067篇
  2018年   1064篇
  2017年   1034篇
  2016年   1136篇
  2015年   1127篇
  2014年   2015篇
  2013年   2118篇
  2012年   1667篇
  2011年   1800篇
  2010年   1387篇
  2009年   1242篇
  2008年   1166篇
  2007年   1116篇
  2006年   928篇
  2005年   776篇
  2004年   620篇
  2003年   516篇
  2002年   433篇
  2001年   405篇
  2000年   365篇
  1999年   278篇
  1998年   220篇
  1997年   169篇
  1996年   176篇
  1995年   134篇
  1994年   113篇
  1993年   124篇
  1992年   92篇
  1991年   105篇
  1990年   71篇
  1989年   82篇
  1988年   79篇
  1987年   64篇
  1986年   41篇
  1985年   85篇
  1984年   46篇
  1983年   39篇
  1982年   62篇
  1981年   31篇
  1980年   41篇
  1979年   40篇
  1978年   33篇
  1977年   19篇
  1976年   17篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
61.
While much time has been spent deliberating about the definition of play, little emphasis has been placed on what children themselves perceive as play. The aim of the present study was to examine social context as a cue for children's perceptions of play and learning. Ninety-two children aged between four and six years (mean four years nine months) participated in the study and completed the Activity Apperception Story Procedure. Children were asked to sort photographic stimuli into those they believed depicted play/not play and learning/not learning. Each of the stimuli were identified by independent raters as containing one of the following social cues; teacher absence (solitary activity, parallel activity or cooperative activity) or teacher presence (teacher involved activity or teacher directed activity). Findings revealed that children associated teacher absence with play. More specifically, children made links between play and the presence of peers (parallel and cooperative activity). Findings are discussed in relation to play in the early years curriculum, differences in children's early educational experiences and the importance of understanding children's perceptions of play.  相似文献   
62.
经鼻肠管肠内营养在胃癌根治术中的应用   总被引:2,自引:0,他引:2  
目的探讨经鼻肠管肠内营养(EN)在胃癌根治术患者中的应用效果。方法在72例行胃癌根治术患者中,34例术后行肠外营养(PN)治疗,38例应用鼻肠管于术后早期行肠内营养(EN)治疗。结果术后EN组的血红蛋白和血清蛋白与PN组基本相同,而AKP、GGT和TB明显低于PN组。结论经鼻肠管的EN比PN更适合胃癌根治术患者的营养支持治疗。  相似文献   
63.
生理盐水肠道冲洗辅助治疗真菌性肠炎效果观察   总被引:2,自引:0,他引:2  
目的 探讨生理盐水肠道冲洗辅助治疗真菌性肠炎的疗效。方法 将72例真菌性肠炎患者随机分为观察组和对照组各36例,对照组行常规治疗,观察组在此基础上予以温生理盐水(38~41℃)500~7000ml持续肠道冲洗,3~6h/次,1次/d,治疗1~3次。结果 观察组治疗后肠道pH值显著低于治疗前及对照组治疗后(均P〈0.01),治愈率显著高于对照组(P〈0.01)。结论 对真菌性肠炎腹泻患者在常规治疗的基础上,辅以温生理盐水肠道冲洗可显著改善肠道环境,提高治愈率。  相似文献   
64.
成都郊区学龄前儿童钙营养及骨矿状况的调查   总被引:2,自引:1,他引:1  
目的:了解郊区学龄前儿童的膳食钙营养及骨矿发育状况。方法:随机选取成都郊区两所幼儿园,对161名3~6岁儿童进行膳食调查,检测血钙、尿钙,并用DEXA法、超声骨量分别测腰椎骨矿及跟骨骨量。结果:郊区学龄前儿童膳食钙营养状况仍较差。只达推荐量的32%左右;低血钙、低尿钙百分率分别为42.24%、63.34%;骨量、骨密度、骨面积与体重、身高呈正相关,学龄前儿童已表现出骨密度差异,男孩较女孩高,郊区学龄前儿童骨矿状况较城市同龄儿童为低。结论:郊区学龄前儿童由于膳食结构不合理。钙营养不足,低尿钙、血钙发生率较高,骨量发育较城市明显落后。必须加强人们对钙营养重要性的认识,调整膳食结构,多食人奶制品、豆制品等含钙丰富的食物,改普钙营养状况。促进达到最佳骨量。  相似文献   
65.
547例垂体腺瘤延迟诊断原因及影像诊断分析   总被引:2,自引:0,他引:2  
目的:提高垂体腺瘤特别是微腺瘤早期影像诊断率。方法:通过对所搜集病史资料完整,经医学影像学确诊和手术病理证实的547例垂体腺瘤(内有251例微腺瘤)延迟诊断原因的分析,找到影响垂体腺瘤早期诊断的因素。结果:296例垂体大腺瘤蝶鞍X线平片、CT、MR常规检查即可诊断。CT骨窗蝶鞍片有助于垂体微腺瘤的诊断,251例微腺瘤经高分辨力CT薄层冠状强化扫描和高场强MR薄层强化扫描得以明确诊断。结论:熟悉垂体腺瘤的首发症状,及时行CT、MR常规扫描可明确大腺瘤的诊断,CT骨窗片可发现垂体微腺瘤的佐证。高场强MR薄层强化扫描是目前诊断垂体微腺瘤的最佳方法,高分辨力CT冠状薄层强化扫描次之,结合神经内分泌学检查是提高垂体腺瘤影像学早期诊断率的主要措施。  相似文献   
66.
BACKGROUND: Dialysis patient mortality remains high, and this high mortality may be due to many factors. In peritoneal dialysis (PD) patients, old age, co-morbid diseases, malnutrition, low residual renal function (RRF) and a high peritoneal transport rate have been shown to influence survival, but the relative importance of these factors may differ between different patient populations. Besides, centre practice patterns may differ between centres and may influence patient survival. In addition, the literature suggests that dialysis patient survival may be better in Asian than in Caucasian patients. METHODS: The influence of centre and patient characteristics on patient survival was investigated in 132 Korean and 106 Swedish incident PD patients, who underwent initial biochemical measurements and assessment of adequacy of dialysis, nutritional status, RRF and peritoneal transport characteristics. RESULTS: At the start of PD, Korean patients had a higher prevalence of diabetes, peritoneal Kt/V(urea), peritoneal creatinine clearance and peritoneal fluid removal, and lower body mass index, RRF and dialysate to plasma creatinine concentration ratio (D/P Cr) compared with Swedish patients. Significantly more patients from Korea were placed on temporary haemodialysis before PD (100 out of 132) when compared with Swedish patients (21 out of 106). During the follow-up, there was a significantly higher rate of transfer to other units in Korea and a significantly higher rate of kidney transplantation in Sweden. On Kaplan-Meier analysis, overall patient survival did not differ and relative risk for death was also not different between the two centres even after adjustment for age, diabetes, cardiovascular disease, RRF and D/P Cr. On Cox proportional hazards multivariate analysis, age, diabetes, RRF and D/P Cr were found to be independent predictors of mortality in the combined cohort of patients. While age, diabetes and D/P Cr were independent predictors of mortality in Korean patients, age and RRF independently predicted mortality in Swedish patients. CONCLUSION: Although there were significant differences in centre and patient characteristics, we were unable to confirm a survival advantage for Korean over Swedish PD patients. The results of this study suggest that the reported difference in survival between Asian and Caucasian dialysis patients may have been due, in part, to differences in centre and patient characteristics rather than to race as such. The genetic influence on patient characteristics remains, however, to be elucidated.  相似文献   
67.
目的:探讨不同方案治疗早期糖尿病视网膜病变的经济效果,找出既经济又有效的方案。方法:对目前临床常用的4种不同治疗方案(导升明、胰激肽原酶、复方血栓通胶囊、复方丹参滴丸,治疗时间均为90d)运用药物经济学方法进行成本-效果分析。结果:4种方案所需费用分别为1417.50元、810.00元、891.00元、656.10元;治疗有效率分别为94.25%、85.09%、85.17%、83.53%;成本-效果比分别为15.04、9.52、10.46、7.85。结论:复方丹参滴丸治疗效果较好,不良反应少,成本低廉。  相似文献   
68.
BACKGROUND: Abnormal glucose tolerance is a frequent co-morbidity in cystic fibrosis patients (CF), and is associated with a worse prognosis. The objectives are to investigate (a) the relative contribution of insulinopenia and insulin resistance (IR) for glucose tolerance and (b) the association between various glucose parameters and CF clinical status. METHODS: Oral glucose tolerance tests were performed in 114 consecutive CF patients not known to be diabetic as well as 14 controls similar for age and BMI. RESULTS: Abnormal glucose tolerance was found in 40% of patients with CF: 28% had impaired glucose tolerance (IGT) and 12% had new cystic fibrosis related diabetes (CFRD). Compared to control subjects, all CF patients were characterized by an increased glucose excursion (AUC). While reduced early insulin release characterised CF, IGT and CFRD patients also present IR thus both mechanisms significantly contribute to glucose tolerance abnormalities. Increased glucose AUC and reduced early insulin release but not glucose tolerance categories were associated with a reduced pulmonary function (FEV(1)). CONCLUSION: In CF, early insulin secretion defect but also IR contribute to glucose intolerance. Early in the course of the disease, increased glucose AUC and reduced early insulin secretion are more closely associated with a worse clinical status than conventional glucose tolerance categories.  相似文献   
69.
目的 研究应用个体化营养方案对慢性阻塞性肺疾病 (COPD)患者进行营养治疗后的病情变化 ,评价个体化营养方案对病情的影响 ,阐明个体化营养方案的治疗价值。方法 选择 80例COPD患者 ,随机分为实验组与对照组 ,实验组应用个体化方案进行营养治疗 ,对照组采用普通膳食 ,观察营养状况、临床表现、病情急性发作次数、住院次数、治疗费用、并发症、呼吸衰竭发生率、死亡率、肺通气功能的变化。结果 实验组营养状况显著好于对照组P <0. 0 5 ,实验组病情急性发作次数、住院天数减少 ,治疗费用降低 ,与对照组比 ,差异显著P <0 . 0 5 ,实验组临床表现减轻 ,与对照组比差异显著P <0 . 0 5 ,实验组患者肺功能有所改善 ,差异显著P <0 . 0 5 ,实验组并发症、呼衰发生率、死亡率与对照组比显著降低P <0 . 0 5。结论 个体化营养方案简便易行、科学、经济 ,患者易接受 ,应用该个体化营养方案对COPD患者实施营养支持 ,营养效果明显 ,能确切改善患者病情。  相似文献   
70.
术后早期肠内营养对食管癌患者肠黏膜屏障功能的影响   总被引:23,自引:4,他引:19  
目的 探讨食管癌患者术后早期施行肠内营养支持对胃肠道黏膜屏障的保护作用. 方法术前3个月内体重下降超过患病前体重20%的食管癌患者56例,按所给营养方法不同分为肠内营养组(n=30)和肠外营养组(n=26),观察两组患者的临床结果,分别于术后第1、4和8天测定两组患者尿乳果糖与甘露醇的比值、血浆内毒素、肿瘤坏死因子(TNF)、胃泌素和谷氨酰胺水平. 结果肠内营养组患者术后体重减轻较少,感染性并发症发生较少(P<0.01,0.05).术后第4天和8天,肠内营养组尿乳果糖与甘露醇比值、血浆内毒素和TNF较肠外营养组低(P<0.01),胃泌素、谷氨酰胺较肠外营养组高(P<0.01). 结论食管癌患者术后早期肠内营养对肠道黏膜屏障功能具有一定的保护作用,有可能减少术后感染性并发症的发生.  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