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   18010篇
  免费   1241篇
  国内免费   345篇
耳鼻咽喉   129篇
儿科学   506篇
妇产科学   333篇
基础医学   1202篇
口腔科学   279篇
临床医学   1963篇
内科学   5011篇
皮肤病学   265篇
神经病学   870篇
特种医学   861篇
外科学   1630篇
综合类   1370篇
预防医学   1954篇
眼科学   520篇
药学   1520篇
  2篇
中国医学   264篇
肿瘤学   917篇
  2024年   50篇
  2023年   745篇
  2022年   1252篇
  2021年   1677篇
  2020年   1262篇
  2019年   1470篇
  2018年   1310篇
  2017年   782篇
  2016年   512篇
  2015年   510篇
  2014年   1277篇
  2013年   1044篇
  2012年   670篇
  2011年   795篇
  2010年   635篇
  2009年   614篇
  2008年   684篇
  2007年   634篇
  2006年   448篇
  2005年   412篇
  2004年   321篇
  2003年   282篇
  2002年   225篇
  2001年   158篇
  2000年   151篇
  1999年   138篇
  1998年   122篇
  1997年   115篇
  1996年   120篇
  1995年   110篇
  1994年   91篇
  1993年   89篇
  1992年   101篇
  1991年   75篇
  1990年   85篇
  1989年   77篇
  1988年   75篇
  1987年   43篇
  1986年   52篇
  1985年   68篇
  1984年   62篇
  1983年   36篇
  1982年   41篇
  1981年   37篇
  1980年   35篇
  1979年   29篇
  1978年   18篇
  1977年   23篇
  1976年   12篇
  1974年   7篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The national vaccination campaign against SARS-CoV-2 started in January 2021 in Belgium. In the present study, we aimed to use national hospitalisation surveillance data to investigate the recent evolution of vaccine impact on the risk of COVID-19 hospitalisation. We analysed aggregated data from 27,608 COVID-19 patients hospitalised between October 2021 and February 2022, stratified by age category and vaccination status. For each period, vaccination status, and age group, we estimated risk ratios (RR) corresponding to the ratio between the probability of being hospitalised following SARS-CoV-2 infection if belonging to the vaccinated population and the same probability if belonging to the unvaccinated population. In October 2021, a relatively high RR was estimated for vaccinated people > 75 years old, possibly reflecting waning immunity within this group, which was vaccinated early in 2021 and invited to receive the booster vaccination at that time. In January 2022, a RR increase was observed in all age categories coinciding with the dominance of the Omicron variant. Despite the absence of control for factors like comorbidities, previous infections, or time since the last administered vaccine, we showed that such real-time aggregated data make it possible to approximate trends in vaccine impact over time.  相似文献   
72.
We assessed standardized mortality ratio in tick-borne encephalitis (TBE) in Sweden, 2004–2017. Standardized mortality ratio for TBE was 3.96 (95% CI 2.55–5.90); no cases in patients <40 years of age were fatal. These results underscore the need for further vaccination efforts in populations at risk for TBE.  相似文献   
73.
目的:观察孔源性视网膜脱离手术后视网膜复位及视力恢复情况;黄斑区OCT图形特征。方法:77例77眼裂孔型视网膜脱离在巩膜扣带术前后,行除常规检查外,拍摄眼底像,行黄斑区OCT检查[以黄斑中心凹为中心"十"字扫描,5.62mm标准扫描线,测量中心凹神经纤维(NF)厚度,及视网膜下残液量,并打印出图像];术后1wk;1,2,3,6mo随访矫正视力、眼底及OCT。结果:本组视网膜脱离患者手术后临床复位率100%,而OCT扫描显示,术后1wk解剖复位率52%,术后1mo62%,术后2mo71%,术后3mo75%,术后6mo87%;术后视力在3~6mo内逐渐提高并稳定;黄斑区OCT图形异常提示视功能改善差。结论:OCT是视网膜脱离手术前后了解和观察病情、预测预后的可靠手段。  相似文献   
74.
75.
BackgroundPlatelets play a vital role in the neoplastic process. Platelet parameters are hence an important source of information concerning ongoing neoplastic disease. The aim of the study is to assess the impact of selected platelet parameters on the survival of patients with non-small cell lung cancer (NSCLC).MethodsThe study included 532 (174 female and 358 male) patients aged 36–84 years (mean age 63.6 years) operated on due to NSCLC, staged IA–IIIA. Before the operation, all patients received a blood morphology test. The following parameters were subjected to statistical analysis: platelet count, mean platelet volume (MPV) parameter, platelet distribution width (PDW) parameter, platelet-to-lymphocyte ratio (PLR) and systemic immune-inflammation (SII) index. These findings were compared with the clinical data of the patients, and the probability of overall survival was analyzed.ResultsThe univariate analysis revealed a correspondence between PDW, MPV, PLR and SII index and patient survival. The multivariate analysis including patient clinical data found the following factors to have negative prognostic value for patients operated on due to NSCLC: male sex, advancement stage of neoplastic disease and Charlson Comorbidity Index (CCI) above 4, and PLR >144.ConclusionsPDW value, PLR and SII index are independent prognostic factors. In the multi-factor model, male sex, the advancement stage of the neoplastic disease, CCI above 4 and PLR lower than 144 had the greatest prognostic value.  相似文献   
76.
Predicting the prognosis and adverse events (AEs) of nivolumab therapy for recurrent esophageal cancer is very important. The present study investigated whether a simple blood biochemical examination could be used to predict prognosis and AEs following nivolumab treatment for relapse of esophageal cancer. A total of 41 patients who received nivolumab treatment for recurrent esophageal cancer after esophagectomy were analyzed. The absolute lymphocyte count (ALC), neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), monocyte-lymphocyte ratio (MLR) and C-reactive protein-albumin ratio (CAR) were assessed at the time of nivolumab induction as indices that can be calculated by blood biochemical examinations alone. Median values were 1,015 for ALC, 3.401 for NLR, 242.6 for PLR, 0.458 for MLR and 0.119 for CAR, and patients were divided into two groups according to values. A high ALC, low NLR, low PLR, low MLR and low CAR were associated with a better response to nivolumab. In addition, patients with the aforementioned indices, with the exception of low PLR, or better response were more likely to develop AEs in univariate analysis. In multivariate analysis, a high ALC [odds ratio (OR): 4.857, P=0.043] and low CAR (OR: 9.099, P=0.004) were identified as independent risk factors for AEs. Survival analysis revealed that overall survival and progression-free survival (PFS) rates after nivolumab treatment differed significantly between the high and low groups of ALC, NLR, PLR, MLR and CAR. The multivariate analysis identified a low ALC [hazard ratio (HR): 3.710, P=0.003] and high CAR (HR: 2.953, P=0.007) as independent poor prognostic factors of PFS. In conclusion, ALC and CAR have potential as biomarkers for outcomes of recurrent esophageal cancer following nivolumab treatment.  相似文献   
77.
Background: The purpose of this study was to measure and compare the strain levels in the peri-implant bone as generated by the blade-like implant (BLI) and the screw-type implant (STI) with two different internal connections (hexagonal and conical) and with a 1:1 and 2:1 crown/implant (C/I) ratio. Methods: The implants (BLI and STI) were placed into sawbones according to the manufacturer’s protocol. Two strain gauges, horizontal and vertical to the implant axis, were placed around each implant on the bone surface 1 mm from the cervical part. Each implant was loaded by a material testing machine at a force of 100 N. Micro-strains (με) generated in the surrounding bone were measured by a strain gauge and recorded. Results: Recorded micro-strains were not significant in both the insertion and loading phases (p < 0.0625). The average recorded micro-strain values were lower in the horizontal dimension of STI with hexagonal connection when the C/I ratio was 2:1 compared with BLI, 210 με and 443 με, respectively. Conclusion: Within the limitations of this study, implant design, implant-abutment connection and C/I ratio did not influence strain values in bone and there is no statistically significant effect of these parameters on bone.  相似文献   
78.
Objective: Whether dietary carbohydrate (CHO) or fat is more involved in type 2 diabetes (T2DM) induction uncomplicated by dietary fiber was addressed in a spontaneous diabetic model, the diurnal Nile rat that mimics the human condition. Methods: A total of 138 male Nile rats were fed plant-based and animal-based saturated fat where 10% energy as CHO and fat were exchanged across 5 diets keeping protein constant, from 70:10:20 to 20:60:20 as CHO:fat:protein %energy. Diabetes induction was analyzed by: 1. diet composition, i.e., CHO:fat ratio, to study the impact of diet; 2. quintiles of average caloric intake per day to study the impact of calories; 3. quintiles of diabetes severity to study the epigenetic impact on diabetes resistance. Results: High glycemic load (GLoad) was most problematic if coupled with high caloric consumption. Diabetes severity highlighted rapid growth and caloric intake as likely epigenetic factors distorting glucose metabolism. The largest weanling rats ate more, grew faster, and developed more diabetes when the dietary GLoad exceeded their gene-based metabolic capacity for glucose disposal. Diabetes risk increased for susceptible rats when energy intake exceeded 26 kcal/day and the GLoad was >175/2000 kcal of diet and when the diet provided >57% energy as CHO. Most resistant rats ate <25 kcal/day independent of the CHO:fat diet ratio or the GLoad adjusted to body size. Conclusion: Beyond the CHO:fat ratio and GLoad, neither the type of fat nor the dietary polyunsaturated/saturated fatty acid (P/S) ratio had a significant impact, suggesting genetic permissiveness affecting caloric and glucose intake and glucose disposition were key to modulating Nile rat diabetes. Fat became protective by limiting GLoad when it contributed >40% energy and displaced CHO to <50% energy, thereby decreasing the number of diabetic rats and diabetes severity.  相似文献   
79.
绵羊产后诱发发情试验   总被引:2,自引:0,他引:2  
本试验利用多种方案对90只哺乳母羊采用羔羊提前断奶、公羊性刺激并结合激素处理发发情,以达到缩短产羔间隔,提高繁殖率的目的,经试验测定,母羊发情率平均为32.22%,情期受胎率平均为31.03%,效果不理想,需进一步对此进行研究。  相似文献   
80.
目的应用加权秩和比法综合评估血吸虫病防治效果,为血吸虫病防治及政策制定提供参考。方法选择反映血吸虫防治效果三个方面的疫情指标体系:人群感染情况、家畜感染情况、洲滩危险指标,并通过德尔菲法建立各指标的组合权重,再应用加权秩和比(RSRw)法对3个试点村连续4年的防治效果指标进行综合测评。结果试点村中双坪村及利兴村的RSRw时间序列值逐年升高,并在2009年达到最高,预示着两村的血吸虫病防治效果较好且呈逐年上升趋势,而灯塔村的RSRw时间序列值有所波动,且存在下滑趋势,意味着灯塔村的血吸虫病防治效果欠佳,防治工作质量有待加强。结论加权秩和比法可克服单一评估指标的不足,给人整体感,所包含信息量大,操作简单,应用性强,在评估血吸虫病防治效果中能综合直观地反映血吸虫病的防治效果及趋势,可为血吸虫病防治政策的制定及防治重点提供科学的参考。  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