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   14270篇
  免费   1178篇
  国内免费   388篇
耳鼻咽喉   933篇
儿科学   524篇
妇产科学   104篇
基础医学   1848篇
口腔科学   720篇
临床医学   1702篇
内科学   2183篇
皮肤病学   20篇
神经病学   573篇
特种医学   784篇
外国民族医学   2篇
外科学   2206篇
综合类   2004篇
现状与发展   2篇
一般理论   1篇
预防医学   624篇
眼科学   95篇
药学   964篇
  7篇
中国医学   348篇
肿瘤学   192篇
  2024年   22篇
  2023年   265篇
  2022年   381篇
  2021年   560篇
  2020年   598篇
  2019年   540篇
  2018年   563篇
  2017年   570篇
  2016年   559篇
  2015年   549篇
  2014年   937篇
  2013年   1010篇
  2012年   807篇
  2011年   884篇
  2010年   722篇
  2009年   742篇
  2008年   726篇
  2007年   725篇
  2006年   600篇
  2005年   542篇
  2004年   451篇
  2003年   400篇
  2002年   345篇
  2001年   298篇
  2000年   238篇
  1999年   236篇
  1998年   193篇
  1997年   181篇
  1996年   166篇
  1995年   139篇
  1994年   114篇
  1993年   92篇
  1992年   82篇
  1991年   70篇
  1990年   43篇
  1989年   56篇
  1988年   48篇
  1987年   37篇
  1986年   36篇
  1985年   67篇
  1984年   41篇
  1983年   29篇
  1982年   38篇
  1981年   22篇
  1980年   24篇
  1979年   22篇
  1978年   11篇
  1977年   20篇
  1976年   15篇
  1975年   6篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
目的:通过对颈椎病患者上下终板弧形高度、椎间隙高度与椎间隙后骨赘的影像学测量,研究其相关性及其临床应用价值。方法:收集2017年9月至2018年9月颈椎病手术108例患者的临床资料,男48例,年龄30~72岁,平均52岁,女60例,年龄37~79岁,平均54岁。其中C2,3 6例,C3,4 15例,C4,5 32例,C5,6 42例,C6,7 13例。术前及术后摄颈椎X线片,利用PACS(Picture Archiving and Communication Systems)调阅影像,测量椎间隙的下上终板弧形高度(L1,L2),椎间隙高度(L3)及后方骨赘的宽度(L4)。利用Spearman分析它们之间的相关性。结果:L1与L4对比(r=-0.34,P<0.05),L3与L4对比(r=-0.36,P<0.05),存在负相关。L1与L3对比(r=0.38,P<0.05),L2与L3对比(r=0.48,P<0.05),存在正相关。L1与L2对比(P>0.05),L2与L4对比(P>0.05),差异无统计学意义。结论:下终板弧形高度与椎间隙后缘骨赘宽度呈负相关,通过其测量可明确颈椎退变程度,对颈椎病的早期防治有指导意义。  相似文献   
3.
4.
目的:比较经鼻导管高流量吸氧(HFNC)与经鼻气道正压通气(nCPAP)在重症毛细支气管炎呼吸支持中的应用价值,为临床治疗方案的选择提供参考。方法:选取2016年12月至2018年12月我院儿科收治的重症毛细支气管炎患儿90例,采用随机数字表法分为观察组和对照组各45例。两组患儿入院后均给予常规综合治疗以保证呼吸道通畅,在此基础上观察组采用HFNC治疗,对照组采用nCPAP治疗,比较两组患儿治疗前和治疗24 h后呼吸频率、经皮血氧饱和度(TcSO2)、呼吸窘迫评分体系(CSS)评分、动脉血氧分压(PaO2)等呼吸相关指标及治疗前后临床症状体征改善情况。结果:两组患儿治疗24 h后呼吸频率、CSS评分均降低,且观察组降低程度更大,TcSO2、PaO2于治疗24 h后升高,观察组升高幅度较对照组明显;治疗后两组患儿咳嗽及肺部湿啰音、肺部炎症情况均改善,观察组症状体征消失时间早于对照组,差异均有统计学意义(P<0.05)。结论:重症毛细支气管炎患儿采用HFNC治疗可明显改善通气功能和临床症状,治疗效果优于nCPAP治疗,可扩大样本量进一步观察。  相似文献   
5.
6.
The objective of this paper was to assess the link between premature mortality and a combination of neighbourhood contextual (environmental and health) and compositional (socioeconomic and demographic) characteristics. We statistically and spatially examined six environmental variables (ultrafine particles, carcinogenic and non-carcinogenic pollutants, pollution released to air, tree cover, and walkability index), six health service indicators (number health providers, breast, colorectal and cervical cancer screening uptake rates, student nutrition program uptake rates, and healthy food index), and eight socioeconomic indicators (total income, Gini coefficient, two age categories – below and above 40 years, proportion of females to males, visible minorities, Indigenous peoples, education, less than grade 9) among 140 neighbourhoods of the City of Toronto in Ontario (Canada). We applied principal component analysis to identify patterns and to reduce the number of explanatory variables into combined component axes that represent unique variation in these confounded and overlapping factors. We then applied regression analysis to model the relationship between the indices of enviro-health and socioeconomics and their potential relationship with premature mortality. Residual spatial analysis was used to investigate any remaining spatial structure (such as neighbourhoods with higher residual premature mortality rates). Neighbourhood Equity Index was correlated with our enviro-health and socioeconomic indices. Premature mortality within neighbourhoods was predicted by poor cancer screenings, pollution, lack of tree canopy, increased uptake of student nutrition programs and high walkability index. A negative association between premature mortality and pollution was associated low walkability index and presence of visible minorities within neighbourhoods. There was some unexplained residual spatial variation in our model of premature mortality - especially along the shores of Lake Ontario and in neighbourhoods with major highways or road corridors: premature mortality in Toronto neighbourhoods was higher than expected along highway-corridor neighbourhoods and shorelines. Our analysis revealed a significant relationship between neighbourhood contextual features – both environmental and health – and premature mortality, suggesting that these contextual components of neighbourhoods can predict rates of urban premature mortality in Toronto.  相似文献   
7.
本文回顾了Er:YAG激光活化根管冲洗技术的最新研究进展,包括光子诱导光声流(photon initiated photoacoustic streaming,PIPS)技术和冲击波增强发射光声流(shock wave enhanced emission photoacoustic streaming,SWEEPS)技术,探讨Er:YAG激光预处理桩道的原理、优点以及对纤维桩粘接强度的影响,以期为临床选择适宜的桩道处理方法提供新思路。  相似文献   
8.
Background/objectiveObstructive sleep apnea (OSA) is independently associated with dyslipidemia, a surrogate marker of atherosclerosis. Low-density lipoprotein (LDL)-cholesterol is accepted as a major independent risk factor for cardiovascular disease. However, non-high-density lipoprotein (HDL)-cholesterol is a better marker of atherogenic dyslipidemia and recommended as a target of lipid lowering therapy. We aimed to assess the prevalence of atherogenic dyslipidemia, and relationship between OSA severity and serum LDL-cholesterol and non-HDL cholesterol levels in OSA patients.MethodsWe retrospectively evaluated treatment naïve 2361 subjects admitted to the sleep laboratory of a university hospital for polysomnography. All subjects’ lipid profile including total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, and non-HDL-cholesterol were measured.ResultsOut of 2361 patients (mean age 49.6 ± 11.9 years; 68.9% male, apnea-hypopnea index 36.6 ± 28.4/h), 185 (7.8%) had no OSA and 2176 (92.2%) had OSA. Atherogenic dyslipidemia prevalence was high (57–66%) in OSA patients, and especially increased in severe OSA compared to other groups (p < 0.05). Though total and LDL-cholesterol did not differ between those with and without OSA, non-HDL-cholesterol (p = 0.020), and triglycerides (p = 0.001) were higher and HDL-cholesterol levels (p = 0.018) were lower in OSA patients than non-OSA. Non-HDL-cholesterol was significantly correlated with OSA severity (p < 0.001) and hypoxia parameters (p < 0.01), whereas LDL-cholesterol showed no correlation.ConclusionsAtherogenic dyslipidemia is highly prevalent and non-HDL-cholesterol levels are significantly increased, predominantly in severe OSA patients. Non-HDL-cholesterol but not LDL-cholesterol, is significantly correlated with OSA severity and hypoxia parameters. Therefore, it could be better to use non-HDL-cholesterol, which is a guideline recommended target of lipid therapy, as a marker of atherosclerotic cardiovascular risk in OSA patients.  相似文献   
9.
10.
近年来,医疗器械口咽通气道产品的注册数量日益增加,针对该产品的相关咨询也逐渐增多。但该产品暂无相关的注册技术审查指导原则,以致该产品的注册申报资料经常出现一些共性问题。现根据医疗器械口咽通气道产品相关法规和标准,对日常工作中遇到的常见问题进行归纳,分析该产品注册申报中的技术审评要求及共性问题,并给出对策或建议。  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