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   67376篇
  免费   5626篇
  国内免费   1704篇
耳鼻咽喉   1222篇
儿科学   2240篇
妇产科学   921篇
基础医学   6531篇
口腔科学   1220篇
临床医学   5916篇
内科学   10990篇
皮肤病学   2829篇
神经病学   5976篇
特种医学   2568篇
外国民族医学   2篇
外科学   5494篇
综合类   7467篇
现状与发展   3篇
预防医学   5749篇
眼科学   1323篇
药学   8745篇
  29篇
中国医学   2717篇
肿瘤学   2764篇
  2024年   68篇
  2023年   631篇
  2022年   1012篇
  2021年   2269篇
  2020年   1985篇
  2019年   2216篇
  2018年   2433篇
  2017年   2261篇
  2016年   2233篇
  2015年   2217篇
  2014年   3630篇
  2013年   4417篇
  2012年   3547篇
  2011年   3767篇
  2010年   3126篇
  2009年   2834篇
  2008年   2999篇
  2007年   3024篇
  2006年   2531篇
  2005年   2310篇
  2004年   1929篇
  2003年   2054篇
  2002年   2638篇
  2001年   2776篇
  2000年   2823篇
  1999年   2018篇
  1998年   1797篇
  1997年   1653篇
  1996年   1115篇
  1995年   787篇
  1994年   593篇
  1993年   472篇
  1992年   501篇
  1991年   458篇
  1990年   378篇
  1989年   376篇
  1988年   341篇
  1987年   311篇
  1986年   272篇
  1985年   321篇
  1984年   261篇
  1983年   226篇
  1982年   224篇
  1981年   179篇
  1980年   152篇
  1979年   110篇
  1978年   97篇
  1977年   88篇
  1976年   59篇
  1975年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.

Background

One daily dose of tacrolimus (QDT) improves adherence in kidney transplant (KT) recipients. A switch from twice-daily tacrolimus (BDT) to QDT showed similar efficacy and safety.

Methods

The aim of our study was to demonstrate the long-term efficacy and safety of switching from BDT to QDT in KT recipients. Preliminary results have already been published. Forty-one patients (34 men and 7 women), mean age at KT of 43.9 ± 12.7 years, underwent a 1:1 dose switch from BDT to QDT; the mean time from KT to switch was 36.6 ± 16.1 months. In our study population, 4 patients received a living donor KT and 2 received a second allograft.

Results

The mean follow-up was 86.8 ± 13 months from the switch and 126.2 ± 22.3 months from KT. Graft and patient survival rates were 90.2% and 95.1%, respectively. All patients maintained stable renal function during follow-up. During the first 3 months after the switch we observed a significant decrease in tacrolimus blood level (P = .0001). No significant differences were observed regarding tacrolimus dose before and after QDT introduction (P = not significant [NS]). Fourteen patients who stopped steroids under BDT treatment and 16 patients who stopped steroids after the switch are currently steroid-free.

Conclusion

Our study showed safety and efficacy in switching from BDT to QDT. After early (<1 year) dose adjustment, tacrolimus blood levels remained stable throughout follow-up. Moreover, QDT represented a valid alternative for patients showing steroid side effects.  相似文献   
62.
63.
目的:研究制定知母种子的质量分级标准。方法:通过对不同产地20个批次知母种子的净度、千粒质量、含水量、生活力、发芽率等指标测定和外观形态观察,利用Excel 2010、SPSS 20.0软件对以上数据进行相关分析、主成分以及K-均值聚类分析,初步确定知母种子质量分级指标和分级标准,且以各等级知母种子分别在田间对比种植,通过测定1年产苗量,2年药材产量及有效成分含量,验证知母种子质量分级标准的合理性。结果:Ⅰ级知母种子发芽率不低于85%,千粒质量不低于7.5 g,净度不低于95%;Ⅱ级知母种子发芽率不低于70%,千粒质量不低于7.0 g,净度不低于85%;Ⅲ级知母种子发芽率不低于65%,千粒质量不低于6.0 g,净度不低于80%;各级种子含水量均小于10%。结论:发芽率和千粒质量为知母种子质量分级标准的主要指标,净度和含水量为参考指标。不同等级知母种子种植后对知母种苗产量、药材产量及质量会有显著影响。该研究制定的知母种子质量分级标准科学可行、符合生产实际,为知母的种子质量评价和规范化栽培提供参考依据。  相似文献   
64.
ObjectivesEarly diagnosis of cognitive impairment is increasingly emphasized in the literature to facilitate timely preventive interventions. Although bedside cognitive tests such as the Montreal Cognitive Assessment (MoCA) are widely used for such early diagnostic purposes, they may not have comparable performance to a full neuropsychological battery (FNB) in diagnosing early cognitive impairment. This study investigated whether a small subset of neuropsychological tests can be added on to MoCA to match its performance to that of the FNB in discriminating mild cognitive impairment and dementia (MCI/dementia) from normal cognition.DesignCross-sectional diagnostic study.SettingAlzheimer's Disease Centers across the United States.ParticipantsOlder participants (≥50 years) who completed MoCA and the FNB (N = 9187).MeasuresThe study sample was split into two: the derivation sample (n = 1837) was used to develop a brief neuropsychological battery that best discriminated MCI/dementia (using the best-subset approach with 10-fold cross-validation); while the validation sample (n = 7350) verified its actual performance in discriminating MCI/dementia.ResultsA 3-item neuropsychological battery was identified, comprising MoCA, Benson Complex Figure Recall, and Craft Story 21 Delayed Recall. It had excellent performance in discriminating MCI/dementia from normal cognition (area under the receiver operating characteristic curve [AUROC] 90.0%, 95% confidence interval [CI] 89.2%-90.7%), which was comparable to that of the FNB (AUROC 88.4%, 95% CI 87.6%-89.2%). By contrast, MoCA alone had significantly worse AUROC (86.9%, 95% CI 86.0%-87.7%) than that of the FNB.Conclusions/ImplicationsUsing rigorous methods, this study developed a brief neuropsychological battery that maintained the brevity of a bedside cognitive test, while rivaling the diagnostic performance of an FNB in early cognitive impairment. This brief battery offers a viable alternative when the FNB is needed but cannot be feasibly administered in nonspecialty clinics. It can have a wider health systems effect of improving patients’ access to accurate diagnosis in early cognitive impairment and facilitating timely interventions to delay the progression of cognitive impairment.  相似文献   
65.
尽早发现故障苗头,并将故障消灭于萌芽状态,是预防性维修的目的,是维修工作的最高境界,具体工作包括定期保养,定期检查,随即处置隐患,根据从业多年经验小结了一些针对螺旋CT的预防性维修感受。  相似文献   
66.
复方碘酊消毒液中和剂试验研究   总被引:1,自引:1,他引:0  
复方碘酊消毒液是含有20 g/L碘和1 g/L三氯羟基二苯醚的酒精溶液,为选择出合适的中和剂,采用化学中和法的悬液定量试验和滤膜冲洗及中和剂加滤膜冲洗法进行了试验研究。结果,硫代硫酸钠、硫代乙醇酸钠、吐温80、卵磷脂及其复方中和剂经悬液定量试验法和滤膜冲洗法,均不能中和复方碘酊消毒液对试验菌的残留作用。采用中和剂加滤膜冲洗法证明,用含5000 mg/L硫代硫酸钠+5000 mg/L吐温80+2000 mg/L硫代乙醇酸钠的磷酸盐缓冲液作为中和剂,均可有效去除复方碘酊消毒液对试验菌的残留作用;各中和剂及其中和产物对试验菌及培养基无不良影响。结论,选择复方碘酊消毒液的中和剂,不适宜用悬液定量试验法;宜采用滤膜过滤冲洗法。  相似文献   
67.
68.
氯氮平和利培酮对精神分裂症患者体质量的影响   总被引:1,自引:0,他引:1  
目的:探讨氯氮平和利培酮对精神分裂症患者体质量(体重)的影响及相关因素。方法:选择符合国际疾病分类第10版(ICD-10)精神分裂症的诊断标准,空腹血糖正常,无严重躯体疾病,1周内未用任何抗精神病药的住院患者,共计65例,其中利培酮组32例,氯氮平组33例。两组患者于治疗前和治疗6周末分别做葡萄糖耐量试验,测空腹血胰岛素,测量体质量、身高,计算体质量指数(BMI),评定阳性与阴性症状量表(PANSS)。结果:①治疗后体质量增加者氯氮平组24例(占72.7%),利培酮组19例(占59.4%);氯氮平组体质量平均增加2.5kg,利培酮组1.4kg;②氯氮平组体质量增加与进食量增加、胰岛素水平增加和PANSS评分减分率相关(P<0·05),体质量增加者餐后1h血糖升高;③利培酮组体质量增加与年龄、病程显著相关(P<0·05),与基础BMI存在负相关倾向;④两组治疗后均出现糖耐量减低(IGT)和暂时诊断糖尿病(DM)。结论:氯氮平和利培酮均能导致体质量增加,体质量增加更易对糖代谢造成不良影响。  相似文献   
69.
Background and Aim: This study investigated the clinical features of hepatocellular carcinoma in patients with sustained virological response to interferon for hepatitis C viral (HCV) infection. Methods: A total of 7715 patients with HCV infection were treated with interferon and followed up for more than 1 year after withdrawal of interferon in 64 Japanese hospitals and clinics between July 1988 and August 2001. Sustained virological response was obtained in 2515 (32.6%) patients. Of these 2515 patients, clinical data were collected for 38 patients in whom hepatocellular carcinoma developed. Sustained virological response was defined as HCV RNA negativity more than 6 months after the termination of interferon. Results: All patients were HCV RNA negative at the time of diagnosis of hepatocellular carcinoma. The median period until the detection of hepatocellular carcinoma was 4.7 years (range 1.4–9.0 years). There were significant improvements in hepatic function including serum albumin, aspartate aminotransferase, alanine aminotransferase, indocyanine green test, platelet count and histological activity grade in comparison with those before interferon therapy and at the onset of hepatocellular carcinoma. The maximum tumor size in patients without medical follow‐up for 1 year or more (median: 60 mm) was significantly larger than in patients who were periodically followed up for 6 months or less (median: 25 mm) (P = 0.002). Conclusions: The present findings emphasize the importance of regular medical follow up of patients with HCV infection, as even patients showing a sustained virological response to interferon and in whom hepatic function has improved have the potential to develop hepatocellular carcinoma.  相似文献   
70.
Ames试验检测三硝基甲苯及其还原代谢产物的诱变性   总被引:1,自引:1,他引:0  
应用Ames试验检测系统观察了三硝基甲苯及其还原代谢产物4-羟氨基-2,6-二硝基甲苯(4-HA),4-氨基-2,6-二硝基甲苯(4-A),2-氨基-4,6-二硝基甲苯(2-A)和2,4-二氨基-6-硝基甲苯(2,4-DA)的诱变活性,实验结果显示,三硝基甲苯及其代谢产物具有明显的致突变作用,4-A的直接诱变活性最强,而且移码型诱变性更为显著,在微粒体酶系统的参与下,TNT的诱变活性增强,其代谢产  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