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   66680篇
  免费   5675篇
  国内免费   3278篇
耳鼻咽喉   1164篇
儿科学   789篇
妇产科学   808篇
基础医学   9416篇
口腔科学   1191篇
临床医学   7451篇
内科学   11348篇
皮肤病学   1193篇
神经病学   4297篇
特种医学   3547篇
外国民族医学   21篇
外科学   7495篇
综合类   6283篇
现状与发展   13篇
一般理论   7篇
预防医学   3532篇
眼科学   1667篇
药学   6568篇
  38篇
中国医学   2561篇
肿瘤学   6244篇
  2024年   182篇
  2023年   944篇
  2022年   2413篇
  2021年   3448篇
  2020年   2368篇
  2019年   2362篇
  2018年   2422篇
  2017年   2141篇
  2016年   2300篇
  2015年   3318篇
  2014年   3888篇
  2013年   3823篇
  2012年   5429篇
  2011年   5638篇
  2010年   3540篇
  2009年   2846篇
  2008年   3723篇
  2007年   3575篇
  2006年   3217篇
  2005年   3067篇
  2004年   2240篇
  2003年   2045篇
  2002年   1729篇
  2001年   1203篇
  2000年   1171篇
  1999年   1186篇
  1998年   662篇
  1997年   644篇
  1996年   505篇
  1995年   456篇
  1994年   404篇
  1993年   238篇
  1992年   382篇
  1991年   301篇
  1990年   285篇
  1989年   252篇
  1988年   230篇
  1987年   203篇
  1986年   168篇
  1985年   128篇
  1984年   88篇
  1983年   69篇
  1982年   26篇
  1981年   40篇
  1980年   29篇
  1979年   42篇
  1978年   26篇
  1977年   24篇
  1976年   32篇
  1974年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.

Objective

The advantage of arteriovenous fistulas (AVFs) in older patients requiring dialysis is controversial. We reviewed our vascular access experience in patients ≥70 years of age (older group) compared with younger patients.

Methods

We analyzed consecutive patients who underwent access surgery between 2013 and 2016. Primary success (PS) and primary patency (PP) data were analyzed between the older and younger groups before and after propensity score matching of the patients' characteristics and access composition. PS was defined as the achievement of access function that was amenable to two sessions of successful cannulation without early occlusion or maturation failure requiring revision. PP was defined as the time with uninterrupted patency without intervention.

Results

A total of 594 consecutive accesses were created among 563 patients, of whom 119 were allocated into each group after propensity score matching. In the whole cohort, 193 accesses (32.5%) were performed in older patients. AVFs were performed in 130 (67.4%) older patients and 293 (73.1%) younger patients. Regarding AVFs, the PS rate (83.6% in the older group vs 94.3% in the younger group; P = .001) and the overall PP at 6 and 12 months (73.1% and 57.1%, respectively, in the older group vs 86.7% and 77.7%, respectively, in the younger group; P = .009) were lower in the older group than in the younger group. However, no differences were found in the PS and PP rates for arteriovenous grafts between groups. Regarding the AVF location, the PS rate for forearm AVFs was significantly lower in the older group than in the younger group (76% vs 93%; P < .001); however, the PS rate of the upper arm was not different between the groups (94% vs 97%; P = .425). In the patients with PS, the PP rate of AVFs was similar between the two groups. In the older group with forearm AVFs, the median diameter of the radial artery was larger in the patients with PS than in the patients without PS (2.20 mm with PS vs 2.00 mm without PS; P = .008). The propensity score matching results demonstrated similar trends for the whole cohort, with lower PS (P = .042) and PP rates (P = .023) for AVF in the older group.

Conclusions

The outcomes after AVF were poorer in the older group than in the younger group, which was primarily due to unsatisfactory outcomes in patients with forearm AVFs. Thus, stricter criteria, especially regarding the radial artery diameter, should be applied for forearm AVFs in older patients, and additional research is necessary to delineate the risk factors for primary failure.  相似文献   
2.
3.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
4.
逍遥散出自《太平惠民和剂局方》,由当归、白芍药、柴胡、茯苓、白术、炙甘草、薄荷、煨姜组成。经前期综合征为临床常见的妇科病症,笔者近年来采用逍遥散加减治疗经前期综合征69例,疗效满意,现报道如下。  相似文献   
5.
AIMS: To establish all-cause and cause-specific death rates, and risk factors for mortality in insulin-treated diabetic individuals living in the province of Canterbury, New Zealand. METHODS: Insulin-treated diabetic subjects (n = 995) on the Canterbury Diabetes Registry were followed up over 15 years and vital status determined. Death rates were standardized and hazard regression was used to model the effects of demographic covariates on relative survival time. RESULTS: There were 419 deaths in 11 226.3 person-years of follow-up with a standardized mortality ratio (SMR) of 2.0 (95% confidence interval (CI) 1.8-2.2). Relative mortality was greatest for the group aged 0-29 years (SMR 3.0 (95% CI 2.4-3.7)). After controlling for diabetes duration and gender, a 10-year increment in age of onset was associated with a 33% decrease in relative hazard (95% CI 29-36%), indicating that excess mortality due to diabetes declines with rising age of onset. After controlling for age of onset and gender, each 10-year increment in duration of diabetes is associated with a 26% decrease in relative hazard (95% CI 24-29%), indicating that with longer survival the mortality hazard approaches the general population hazard. Relative mortalities were increased for cardiovascular, renal and respiratory disease, but not malignancy. Relative mortality from acute metabolic complications was increased in the subgroup with age of onset of diabetes < 30 years and requiring insulin within 1 year of diagnosis. CONCLUSIONS: Mortality rates are high for insulin-treated diabetic individuals relative to the general population.  相似文献   
6.
目的 合理应用影像学检查,探讨腰腿痛的病因诊断,为临床治疗提供依据.方法 对38例腰腿痛患者进行随访,观察普通照片后经CT、MRI及B超等复查的最后诊断,对比进行分析.结果 单纯普通照片对椎间盘脱出、椎管狭窄、骶部硬膜外囊肿、股骨头无菌坏死、梨状肌损伤等疾病缺乏直接征象,不能作为诊断依据.结论 应用CT、MRI现代影像技术,同时借助B超、肌电图等相关检查,是确诊腰腿痛病因的有效方法.  相似文献   
7.
COPD机械通气病人下呼吸道感染致病菌分布特点   总被引:1,自引:0,他引:1  
①目的 探讨慢性阻塞性肺病(COPD)病人机械通气后下呼吸道感染致病菌的特点。②方法 取32例COPD并发呼吸衰竭行机械通气病人下呼吸道分泌物做痰细菌学培养,同时做药物敏感试验。③结果 32例病人共分离出菌株76株,阳性率71.7%,其中混合感染10例次。其中革兰阴性杆菌(GNB)58株,占76.3%;阳性球菌10株,占13.2%;真菌8株,占10.5%。常见致病菌以铜绿假单胞菌、鲍曼不动杆菌和肺炎杆菌为主,GNB中铜绿假单胞菌和不动杆菌的耐药率高。④结论 COPD应用机械通气病人下呼吸道感染以革兰阴性杆菌为主,耐药性高。  相似文献   
8.
关于单结合胆红素水溶性的研究   总被引:4,自引:0,他引:4  
目的:进一步研究单结合胆红素(MCB)的水难溶特性及其在病理性胆汁中参与胆红素沉淀和色素性结石形成的作用机制.方法:应用胆红素高效液相色谱分析技术,先从人胆汁中获得结合胆红素,再经分离、制备及纯化得到纯MCB.然后观察其水溶解度并与其它型胆红素比较.结果:在pH7.9,温度37℃接近生理的条件下,MCB的溶解度(558.25±5.96μm)仅为双结合胆红素(DCB)的1/7,比不结合胆红素(UCB)高约44倍并随pH值改变而呈曲线变化.pH7.9时最大;pH4.5时为0;而当pH>9时,反而低于呈离于状态的UCB.结论:MCB虽作为结合型胆红素在胆道生理条件下的不溶性明显高于UCB,但比DCB要低得多;而在胆道病理条件下,其水溶性不但远低于DCB,甚至还不如离子化的UCB,这可能是MCB参与胆红素沉淀及胆色素结石形成的理化基础.  相似文献   
9.
There have been a few studies and inconsistent results regarding the coincidence of Parkinson's disease (PD) and atherosclerotic diseases, such as cerebrovascular disease. Carotid intima-media thickness (IMT) is a known marker for subclinical atherosclerosis. The aim of this study was to investigate the carotid IMT between PD patients and controls. We studied 43 patients with PD and 86 matched controls. The carotid IMT in PD patients was significantly smaller than in controls (0.796 +/- 0.179 mm vs. 0.913 +/- 0.237 mm, P < 0.05). In multivariate analysis, the carotid IMT was inversely associated with the duration of levodopa medication and the severity of PD. These results suggest that PD patients have a lower risk of atherosclerosis.  相似文献   
10.
目的 评价特素(紫杉醇注射液)联合卡铂(伯尔定)方案治疗晚期非小细胞肺癌(NSCLC)的疗效和不良反应.方法 收集我院2004年3月~2006年12月收治的Ⅲb~Ⅳ期的NSCLC患者28例,进行特素(紫杉醇注射液)联合卡铂(伯尔定)化疗.全部患者均有可测量的指标.给药方法:特素135~175mg/m2d1+卡铂5mg·ml^-1·min^-1d2,静脉注射,28天为一周期.结果 全组总有效率50.0%,Ⅲb期有效率62.5%,Ⅳ期有效率45.0%.化疗副反应主要是骨髓抑制及消化道反应,其中Ⅲ~Ⅳ度分别为24.0%、10.7%.结论 特素联合卡铂治疗晚期非小细胞肺癌治疗有效,耐受性良好.  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