全文获取类型
收费全文 | 16795篇 |
免费 | 2912篇 |
国内免费 | 538篇 |
专业分类
耳鼻咽喉 | 102篇 |
儿科学 | 366篇 |
妇产科学 | 151篇 |
基础医学 | 1013篇 |
口腔科学 | 320篇 |
临床医学 | 2556篇 |
内科学 | 2039篇 |
皮肤病学 | 177篇 |
神经病学 | 1044篇 |
特种医学 | 263篇 |
外国民族医学 | 5篇 |
外科学 | 815篇 |
综合类 | 2990篇 |
预防医学 | 2967篇 |
眼科学 | 235篇 |
药学 | 2856篇 |
20篇 | |
中国医学 | 1612篇 |
肿瘤学 | 714篇 |
出版年
2024年 | 43篇 |
2023年 | 464篇 |
2022年 | 726篇 |
2021年 | 1208篇 |
2020年 | 1324篇 |
2019年 | 954篇 |
2018年 | 870篇 |
2017年 | 876篇 |
2016年 | 933篇 |
2015年 | 853篇 |
2014年 | 1564篇 |
2013年 | 1504篇 |
2012年 | 1305篇 |
2011年 | 1291篇 |
2010年 | 966篇 |
2009年 | 799篇 |
2008年 | 700篇 |
2007年 | 675篇 |
2006年 | 561篇 |
2005年 | 456篇 |
2004年 | 328篇 |
2003年 | 284篇 |
2002年 | 245篇 |
2001年 | 223篇 |
2000年 | 184篇 |
1999年 | 115篇 |
1998年 | 111篇 |
1997年 | 64篇 |
1996年 | 67篇 |
1995年 | 62篇 |
1994年 | 67篇 |
1993年 | 52篇 |
1992年 | 39篇 |
1991年 | 28篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 32篇 |
1986年 | 21篇 |
1985年 | 25篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 17篇 |
1981年 | 12篇 |
1980年 | 12篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
32.
目的 对比研究朝鲜淫羊藿酸性多糖酯化还原前后的理化特性,并探讨其改善油酸诱导的肝癌HepG2细胞脂质堆积活性的差异。方法 采用高效凝胶渗透色谱法测定朝鲜淫羊藿酸性多糖(EFPA)的均一性和分子量,高效液相色谱法测定EFPA和酯化还原后朝鲜淫羊藿酸性多糖(EFPA-R)的单糖组成;采用油酸(OA)处理HepG2细胞诱导建立脂质蓄积模型,不同浓度EFPA与EFPA-R(10、30、100、300 μg·mL-1)分别和OA共同作用于细胞24 h,采用CCK-8试剂盒测定细胞存活率,油红O染色观察细胞内脂滴蓄积情况,并采用试剂盒测定细胞内总胆固醇(TC)、甘油三酯(TG)含量。结果 EFPA为成分均一的多糖组分,分子量为125.8 kDa,由甘露糖、葡萄糖、半乳糖、葡萄糖醛酸和阿拉伯糖组成,摩尔比为1.7∶7.4∶1.4∶1.8∶1.0,葡萄糖占比最大,EFPA-R由甘露糖、葡萄糖、半乳糖和阿拉伯糖组成,摩尔比为0.8∶10.6∶2.1∶1.0;在10-300 μg·mL-1范围内,EFPA和EFPA-R对HepG2细胞的抑制作用较弱,作为给药浓度;与空白组相比,模型组细胞中TC、TG含量显著升高(P < 0.01),细胞内红色脂滴显著增多,与模型组相比,EFPA可显著降低细胞中TC、TG含量(P < 0.01),明显减少细胞内红色脂滴(P < 0.05或P < 0.01),EFPA-R干预后细胞则无明显变化。结论 EFPA可明显改善HepG2细胞脂质堆积情况,且呈现剂量依赖性,而半乳糖醛酸(GalA)的存在可能是其抑制HepG2细胞脂质蓄积的关键因素。 相似文献
33.
[摘要] 目的 分析新型冠状病毒肺炎疫情(新冠疫情)暴发前、后2个年度,安庆市流行性感冒(流感)流行的强度和特征。方法 在“中国流感监测信息系统”中选取安庆市2019—2021年度监测数据,分析我市新冠疫情发生前、后的流感样病例就诊百分比、病原学阳性率和聚集性疫情的变化。结果 新冠疫情前、后2个年度,流感样病例就诊百分比分别为4.17%和3.78%,差异有统计学意义(χ2=56.652,P=0.000);病原学阳性率分别为23.43%和1.15%,差异有统计学意义(χ2=538.694,P=0.000)。新冠疫情前的流感病毒活动呈现双峰分布,新冠疫情后全年仅检出27份流感病毒阳性样本。结论 新冠疫情中采取的严格非药物预防措施,对流感的季节性特征有重要影响。应通过疫苗接种和非药物预防等措施,做好流感防控工作。 相似文献
34.
35.
《Journal of Cardiovascular Computed Tomography》2021,15(6):492-498
BackgroundCompared with invasive fractional flow reserve (FFR), coronary CT angiography (cCTA) is limited in detecting hemodynamically relevant lesions. cCTA-based FFR (CT-FFR) is an approach to overcome this insufficiency by use of computational fluid dynamics. Applying recent innovations in computer science, a machine learning (ML) method for CT-FFR derivation was introduced and showed improved diagnostic performance compared to cCTA alone. We sought to investigate the influence of stenosis location in the coronary artery system on the performance of ML-CT-FFR in a large, multicenter cohort.MethodsThree hundred and thirty patients (75.2% male, median age 63 years) with 502 coronary artery stenoses were included in this substudy of the MACHINE (Machine Learning Based CT Angiography Derived FFR: A Multi-Center Registry) registry. Correlation of ML-CT-FFR with the invasive reference standard FFR was assessed and pooled diagnostic performance of ML-CT-FFR and cCTA was determined separately for the following stenosis locations: RCA, LAD, LCX, proximal, middle, and distal vessel segments.ResultsML-CT-FFR correlated well with invasive FFR across the different stenosis locations. Per-lesion analysis revealed improved diagnostic accuracy of ML-CT-FFR compared with conventional cCTA for stenoses in the RCA (71.8% [95% confidence interval, 63.0%–79.5%] vs. 54.8% [45.7%–63.8%]), LAD (79.3 [73.9–84.0] vs. 59.6 [53.5–65.6]), LCX (84.1 [76.0–90.3] vs. 63.7 [54.1–72.6]), proximal (81.5 [74.6–87.1] vs. 63.8 [55.9–71.2]), middle (81.2 [75.7–85.9] vs. 59.4 [53.0–65.6]) and distal stenosis location (67.4 [57.0–76.6] vs. 51.6 [41.1–62.0]).ConclusionIn a multicenter cohort with high disease prevalence, ML-CT-FFR offered improved diagnostic performance over cCTA for detecting hemodynamically relevant stenoses regardless of their location. 相似文献
36.
目的 本研究为探究丹参川芎嗪注射液治疗冠状动脉硬化性心脏病联合用药优效方案。通过全国19家三甲医院信息系统(hospital information system,HIS)数据库中优效人群联合用药规律探讨冠心病治疗中丹参川芎嗪联合用药方案。方法 全国19家三甲医院4952例患者纳入分析,采用真实世界研究方法及Tabu搜索算法。结果 丹参川芎嗪注射液 + 单硝酸异山梨酯 + 速效救心丸 + 阿卡波糖 + 蛋白水解物,为冠心病中西医联合用药频次最高组合,适宜冠心病心绞痛合并糖尿病及缺血性脑血管疾病患者;丹参川芎嗪注射液 + 维生素复方 + 蛋白水解物 + 硝酸甘油 + 头孢类 + 阿卡波糖为最常见西药搭配,用于冠心病合并消化性溃疡、失眠、炎症及糖尿病;活血化瘀制剂(化瘀通脉剂) + 益气养阴剂 + 清热类中药为使用频率最高组合用于冠心病血瘀证合并气阴两虚或阴虚火旺证。结论 目前临床治疗冠心病越来越关注全身治疗,符合中医整体观念及治未病原则。丹参川芎嗪注射液治疗冠心病联合用药符合最新的冠心病诊疗指南。 相似文献
37.
目的 挖掘、分析国医大师刘柏龄治疗脊髓型颈椎病的用药特点及组方规律。方法 收集120份符合纳入标准的刘柏龄教授治疗脊髓型颈椎病的验案,利用Epidata 3.0软件建立方药数据库,使用IBM SPSS Modeler 18.2软件中基于关联规则的Apriori算法,对处方中的中药及其分类的使用频次、中药之间的应用关系进行分析。结果 纳入处方共涉及中药104味,其中使用频次较高的中药依次为黄芪、当归、附子、丹参、赤芍等,用药以补虚药、活血化瘀药、祛风湿药、平肝息风药为主,辅以解表、温里、化湿等药。在关联规则集中,在支持度20%和置信度90%的情况下分析得到二阶、三阶和四阶关联规则,核心药物群包括黄芪、当归、赤芍、附子、红花、桃仁、鸡血藤、地龙、川芎等。结论 刘柏龄治疗脊髓型颈椎病用药具有补虚祛邪并重的鲜明特点,主要采取益气温里助阳、活血化瘀通络、补肾强骨、祛除风湿之邪的治疗原则。 相似文献
38.
Eleftherios G. Kaklamanos Miltiadis A. Makrygiannakis Athanasios E. Athanasiou 《Orthodontics & craniofacial research》2021,24(1):39-51
Immediately after the removal of orthodontic appliances, the teeth might start to drift away from their corrected position in an attempt to reach a new equilibrium. Medications and biologic factors could potentially modulate these processes. The objective of the present systematic review is to systematically investigate and appraise the quality of the evidence regarding the effect of various medications and biologic factors on the rate of relapse following active tooth movement. Search without restrictions in eight databases and hand searching until April 2020 were conducted. Studies performed on animal models investigating the effects of medication and biologic factors on the rate of relapse following orthodontic tooth movement were considered. Following study retrieval and selection, relevant data were extracted and the risk of bias was assessed. Seventeen studies were finally identified, mostly at either high or unclear risk of bias. Ketorolac did not show any significant effects on relapse, while the administration of tetracycline, atorvastatin, psoralen and raloxifene decreased it. Overall, the same result was observed with bisphosphonates with the exception of low dosage of risedronate, which did not have an effect. Osteoprotegerin and strontium resulted in reduced relapse, but not in the immediate post-administration period. Inconsistent or conflicting effects were noted after the use of simvastatin and relaxin. The quality of the available evidence was considered at best as low. It can be concluded that specific medications and biologic factors may have an effect on the rate of relapse following tooth movement. The orthodontist should be knowledgeable about the substances potentially affecting retention. 相似文献
39.
Hideya Yamamoto Yasuki Kihara Shinichiro Fujimoto Hiroyuki Daida Kazuhiro Kobuke Yoshitaka Iwanaga Shunichi Miyazaki Tomohiro Kawasaki Takashi Fujii Sachio Kuribayashi 《Journal of Cardiovascular Computed Tomography》2021,15(2):148-153
BackgroundWhether coronary plaque characteristics assessed in coronary computed tomography angiography (CCTA) in association with the coronary artery calcium score (CACS) have predictive value for coronary events is unclear. We aimed to examine the predictive value of the CACS and plaque characteristics for the occurrence of coronary events.MethodsAmong 2802 patients who were analyzed in the PREDICT registry, 2083 with suspected coronary artery disease (CAD) were studied using post hoc analysis. High-risk plaques were defined as having ≥2 adverse characteristics, such as low computed tomographic attenuation, positive remodeling, spotty calcification, and napkin-ring sign. An adjudicative composite of coronary events (cardiac death, nonfatal acute coronary syndrome, and coronary revascularization ≥3 months after indexed CCTA) were analyzed.ResultsSeventy-three (3.5%) patients had coronary events and 313 (15.0%) had high-risk plaques. Multivariate Cox proportional hazard analysis showed that high-risk plaques remained an independent predictor of coronary events (adjusted hazard ratio [HR] 1.95, 95% confidence interval [CI] 1.13–3.34, P ?= ?0.0154), as well as the log-transformed CACS (adjusted HR 1.24, 95% CI 1.11–1.39, P ?= ?0.0002) and the presence of obstructive stenosis (adjusted HR 5.63, 95% CI 3.22–10.12, P 0.0001). In subgroup analyses, high-risk plaques were independently predictive only in the low CACS class (<100).ConclusionThis study shows that assessment of adverse features by coronary plaque imaging independently predicts coronary events in patients with suspected CAD and a low CACS. Our findings suggest that the clinical value of high-risk plaques to CACS and stenosis assessment appears marginal. 相似文献
40.
《Sleep medicine》2021
ObjectivesInsomnia is a common problem affecting young adult cancer survivors (YACS) even years after treatment, yet it often goes unidentified and untreated. The Insomnia Severity Index is a widely-used insomnia measure, but has not been studied as an insomnia screener for YACS. The goal of this study was to validate the ISI in YACS by determining its utility in identifying YACS with insomnia disorder diagnosed with the Structured Clinical Interview for the DSM-5 (SCID-5).Methods250 YACS completed the ISI and SCID-5 Insomnia Module. Area under the curve (AUC) was calculated to reflect the ISI's discrimination between YACS with and without SCID-5 insomnia disorder. An ISI cut-off score with sensitivity ≥0.85 and specificity ≥0.75 was deemed acceptable.ResultsOf 250 participants, 52 met criteria for SCID-5 insomnia disorder diagnosis. The ISI had excellent discrimination, with an AUC = 0.91. A cut-off score ≥8 met study clinical screening criteria with sensitivity of 0.85 and specificity of 0.77. A cut-off score ≥7 with a higher sensitivity (0.96) but lower specificity (0.70) was noted as a potential alternative. Cut-off scores ≥12 and ≥ 14 were recommended for applications prioritizing overall accuracy.ConclusionsResults support validity of the ISI for identifying YACS with insomnia disorder. For clinical screening, data support the use of an ISI cut-off score ≥8 in YACS, and additional cut-off scores were found for research purposes or higher sensitivity. Results of this study and prior studies of the ISI offer important reminders that cut-off scores derived from different populations are not generalizable. 相似文献