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   47549篇
  免费   4909篇
  国内免费   3963篇
耳鼻咽喉   424篇
儿科学   464篇
妇产科学   501篇
基础医学   5447篇
口腔科学   619篇
临床医学   6292篇
内科学   6237篇
皮肤病学   476篇
神经病学   2792篇
特种医学   1896篇
外国民族医学   20篇
外科学   4710篇
综合类   9384篇
现状与发展   13篇
一般理论   2篇
预防医学   3500篇
眼科学   1232篇
药学   5522篇
  48篇
中国医学   3184篇
肿瘤学   3658篇
  2024年   119篇
  2023年   758篇
  2022年   1478篇
  2021年   2530篇
  2020年   1988篇
  2019年   1621篇
  2018年   1659篇
  2017年   1638篇
  2016年   1487篇
  2015年   2263篇
  2014年   2919篇
  2013年   2661篇
  2012年   3678篇
  2011年   4195篇
  2010年   2895篇
  2009年   2368篇
  2008年   2722篇
  2007年   2707篇
  2006年   2639篇
  2005年   2425篇
  2004年   1716篇
  2003年   1807篇
  2002年   1445篇
  2001年   1170篇
  2000年   1121篇
  1999年   970篇
  1998年   594篇
  1997年   547篇
  1996年   405篇
  1995年   381篇
  1994年   325篇
  1993年   195篇
  1992年   189篇
  1991年   158篇
  1990年   146篇
  1989年   126篇
  1988年   110篇
  1987年   81篇
  1986年   80篇
  1985年   43篇
  1984年   26篇
  1983年   11篇
  1982年   8篇
  1981年   9篇
  1980年   3篇
  1979年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
目的 基于基因组Survey分析对刺果甘草Glycyrrhiza pallidiflora Maxim.基因组大小和杂合率进行估计,并通过叶绿体基因组序列特征对其在甘草属Glycyrrhiza L.中的系统发育位置进行研究。方法 使用二代测序技术对刺果甘草进行测序,采用K-mer方法对测序reads进行分析,估算刺果甘草基因组大小和杂合率,使用生物信息学方法进行叶绿体基因组组装、注释和系统发育分析。结果 Survey分析结果显示其基因组大小约为577.82 Mb,杂合度约为0.31%,重复序列比例约为53.72%。叶绿体基因组长度为127,267 bp,不具有典型的四分体结构,总GC含量为34.32%,包含110个基因,其中76个蛋白质编码基因,30个tRNA基因和4个rRNA基因。系统发育分析表明,刺果甘草与圆果甘草G. squamulosa Franch.亲缘较接近。结论 刺果甘草存在低杂合和重复序列较多的特点,为了更好地对全基因组进行序列拼接和组装,可尝试采用三代测序结合二代测序的分析策略进行基因组组装;刺果甘草叶绿体全基因组比对和系统发育分析,为后续开展甘草属遗传多样性研究和分子鉴定标记筛选提供了重要依据。  相似文献   
22.
目的  测评医学生的共情能力现状,探讨人格特质对其共情能力的影响,为培养医学生的共情能力提供对策。方法  以上海市3所高校临床医学专业学生为研究对象,采用班级整群抽样的方式进行问卷调研。采用杰斐逊共情量表-医学生版(JSPE-S)和大五人格量表(NEO-FFI)分别评估医学生的共情和人格特质。结果  共发放问卷2 020份,回收有效问卷1 958份,有效率为96.93%。医学生的共情能力总分均值为(103.24±14.35)。共情能力总分与大五人格中的“外向性”“开放性”“宜人性”“严谨性”维度呈显著正相关(r=0.154~0.406, P<0.01),与大五人格中的“神经质”维度呈显著负相关(r=-0.175, P<0.01)。分层回归结果表明:“共情重要性”和“大五人格”量表的5个维度进入回归方程。其中,人格因素占可解释方差变异量的16.2%(P<0.01)。结论  我国医学生的共情能力低于国外医学生,重视人格特质的塑造有助于提高其共情能力。  相似文献   
23.
PurposeTwitter is an increasingly popular social media platform within the health care community. The objective of this analysis is to characterize the profile of radiation oncology–related tweets and Twitter users over the past 6 years.Methods and MaterialsUsing the web-based social media analytics platform Symplur Signals, we filtered tweets containing at least 1 of the following hashtags or key words: #radonc, #radiationoncology, "rad onc," or "radiation oncology." We evaluated radiation oncology–related Twitter activity between October 2014 and March 2020 for tweet frequency, tweet content, and individuals or groups posting tweets. We identified the most influential Twitter users contributing to radiation oncology–related tweets.ResultsFrom 2014 to 2020, the quarterly volume of radiation oncology–related tweets increased from 5027 to 29,763. Physicians contributed the largest growth in tweet volume. Academic radiation oncologists comprise 60% of the most influential Twitter accounts responsible for radiation oncology–related content. The number of radiation-oncology resident physicians on Twitter increased from 25 to 328 over the past 6 years, and 20% of radiation-oncology residency programs have a Twitter account. Seventy-one percent of radiation oncology–related tweets generated direct communication via mentions, and 59% of tweets contain links to external sources, including scientific articles.ConclusionsThe number of physicians contributing radiation oncology–related Twitter content has increased significantly in recent years. Academic radiation oncologists are the primary influencers of radiation oncology–related Twitter activity. Twitter is used by radiation oncologists to both professionally network and discuss findings related to the field. There remains the opportunity for radiation oncologists to broaden their audience on Twitter to encompass a more diverse community, including patients.  相似文献   
24.
Objective To observe the clinical characteristics and prognosis of patients with rapidly progressive glomerulonephritis (RPGN) caused by lupus nephritis, antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, or primary glomerulonephritis who were treated with peritoneal dialysis (PD) and then withdrew PD because of renal recovery. Methods Data of the above patients were retrospectively analyzed. The patients were diagnosed as RPGN and received PD therapy in Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University from February 2009 to August 2018. The patients were divided into early withdrawal group (PD time≤183 days, n=24) and late withdrawal group (PD time>183 day, n=24). The differences of clinical characteristics between the two groups were compared. The cumulative incidence of adverse events in both groups was analyzed using Kaplan-Meier curves. Cox proportional hazards model was used to analyze the risk factors influencing the prognosis of patients. Results Forty-eight RPGN patients were included. The median time of maintaining PD was 178(76, 378) days. Compared with the late withdrawal group, the patients in early withdrawal group had lower levels of urine volume, serum albumin and parathyroid hormone, and lower rates of gross hematuria and hypertension at the beginning of PD, and received higher rates of methylprednisolone impulse, combined immunosuppressive agents, and hemodialysis or continuous renal replacement therapy (all P<0.05). At the time of PD withdrawal, the levels of serum creatinine, serum calcium, serum albumin and parathyroid hormone in the early withdrawal group were significantly lower than those in the late withdrawal group (all P<0.05). The Kaplan-Meier curves showed that there was no significant difference in the cumulative survival of patients in both groups (log-rank test χ2=3.485, P=0.062). Cox regression analysis revealed serum creatinine≥209 μmol/L at the time of PD withdrawal was an independent risk factor for poor prognosis (HR=5.253,95%CI 1.757-15.702, P=0.003). Conclusions PD can be used for RPGN patients caused by lupus nephritis, ANCA-associated vasculitis and primary nephritis. Serum creatinine≥209 μmol/L at the time of PD withdrawal is an independent risk factor for poor prognosis.  相似文献   
25.
26.
目的 探讨慕课在我国高等医学教育领域的应用现状和发展趋势,为本领域今后的研究提供参考。方法 检索中国知网、万方数据服务平台、维普数据库、中国生物医学文献数据库建库以来至2020年3月1日收录的相关文献,运用文献计量学方法对年发文量、期刊分布、基金支持、著者分布、被引频次、文献类型和高频关键词进行统计分析。将导出的资料用Excel 2010建立数据库,借助频数分析法进行描述性统计。结果 纳入文献754篇,分别收录于262种期刊;以医学教育类期刊为主;基金资助率达50%;黄坪、张欣、李鑫辉等7人为核心作者;以人体解剖学为代表的基础医学类课程应用研究最多;慕课应用研究以理论课程为主;课程评价包括终末性评价、形成性评价、平台考核、综合能力和自主学习能力5大方面;研究热点为基于慕课的混合式教学模式及其在护理教育、中医教育及继续医学教育中的应用。结论 近5年,慕课在我国高等医学教育中发展迅速,核心作者已形成,但缺乏深度合作。未来应增加实验(训)类课程的应用研究,同时应进一步完善实验性研究的设计及课程评价体系。  相似文献   
27.
目的总结胰十二指肠切除术(PD)后胃排空障碍诊疗的现状与进展。方法检索近年来国内外有关PD后胃排空障碍的相关研究文献并进行综述。结果目前胃排空障碍的病因及发病机制尚未完全阐明,与手术创伤、患者高龄、合并糖尿病、伴有其他腹部并发症等多种高危因素有关。保留幽门PD并不增加术后胃排空障碍的风险,而幽门环切除、结肠前吻合、Braun吻合、微创手术对降低其发生是有利的。胃排空障碍的治疗目前国内外仍无明显进展,但绝大多数患者可通过对症保守治疗获得痊愈。结论 PD后胃排空障碍应以预防为主,围术期应用术后加速康复策略可能是目前临床解决术后胃排空障碍的关键所在,但需进一步研究。  相似文献   
28.
Multidisciplinary predialysis education and team care (MDC) may slow the decline in renal function in patients with chronic kidney disease (CKD). However, associations between unexpected return during MDC and progression of renal dysfunction have not been characterized in patients with CKD. Our study aimed to determine the association between exacerbation of renal dysfunction and the frequency of unexpected return during follow-up.A total of 437 patients with CKD receiving multidisciplinary care between January 2009 and June 2013 at the Shin-Kong Wu Ho-Su Memorial Hospital were included in this retrospective observational cohort study, and multiple imputations were performed for missing data. The predictor was the frequency of unexpected return for follow-up during the first year after entering MDC. Main outcome was monthly declines in estimated glomerular filtration rates (eGFR). Moreover, the demographic data, comorbidities, history of medication, and routine laboratory data for patients with CKD were collected.Among all patients, 59.7% were male, the mean age at initiation of MDC was 69.4 ± 13.2 years, and the duration of follow-up was 21.4 ± 3.3 months. The subjects were divided into 2 groups according to frequencies of follow-up (≤4 and > 4 visits) during the 1st year of MDC. The patients with CKD were regularly followed up every 3 months as a part of MDC in our hospital, and patients who returned for more than 4 follow-up visits were included in the unexpected return group. In crude regression analyses, unexpected return was significantly associated with higher monthly declines of eGFR (β = 0.092, 95% confidence interval, 0.014–0.170). This association remained after adjustments for multiple variables, and subgroup analyses of unexpected return showed that male gender, older age, CKD stage 1 to 3, hypertension, history of coronary artery disease, and use of renin–angiotensin system blockade were significantly associated with declines in renal function.In conclusion, unexpected return for follow-up during the 1st year of MDC was significantly associated with the deterioration of renal function.  相似文献   
29.
目的检测阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患者中血清血管紧张素转换酶(ACE)水平的变化及其临床意义。方法设置OSAHS组(n=40)和健康对照组(n=40),测定并比较患者的血压、血脂和血清ACE水平在两组间的差异;分析ACE水平与患者病情变化、血压、血脂的相关性。结果 OSAHS患者在体重、BMI指数、颈围、腰围、AHI、收缩压、舒张压、TC、LDL-C和血清ACE方面高于健康人(P体重=0.002,P颈围=0.024,P腰围=0.038,PBMI=0.019,PAHI=0.001,P收缩压=0.001,P舒张压=0.001,PTC=0.017,PLDL-C=0.010,PACE=0.039),在LSa O2上低于健康人(PLSa O2=0.001)。OSAHS患者的收缩压、TC、ACE在轻中度和中重度之间均存在统计学差异(P收缩压=0.018、0.043,PTC=0.045、0.034,PACE=0.030、0.001),相关性分析显示,OSAHS患者中血清ACE与收缩压和TC均呈正相关(r=0.35,P=0.017;r=0.28,P=0.044)。结论 OSAHS患者血清ACE能反映患者病情的变化,并与血压和血脂具有一定相关性。  相似文献   
30.
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