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   5225篇
  免费   247篇
  国内免费   75篇
耳鼻咽喉   13篇
儿科学   27篇
妇产科学   11篇
基础医学   414篇
口腔科学   20篇
临床医学   390篇
内科学   800篇
皮肤病学   16篇
神经病学   716篇
特种医学   78篇
外科学   93篇
综合类   367篇
预防医学   282篇
眼科学   26篇
药学   2145篇
  1篇
中国医学   82篇
肿瘤学   66篇
  2023年   31篇
  2022年   33篇
  2021年   88篇
  2020年   87篇
  2019年   98篇
  2018年   102篇
  2017年   131篇
  2016年   129篇
  2015年   126篇
  2014年   287篇
  2013年   683篇
  2012年   241篇
  2011年   297篇
  2010年   259篇
  2009年   253篇
  2008年   304篇
  2007年   252篇
  2006年   228篇
  2005年   176篇
  2004年   147篇
  2003年   177篇
  2002年   131篇
  2001年   100篇
  2000年   105篇
  1999年   95篇
  1998年   66篇
  1997年   64篇
  1996年   59篇
  1995年   62篇
  1994年   58篇
  1993年   57篇
  1992年   42篇
  1991年   26篇
  1990年   31篇
  1989年   29篇
  1988年   27篇
  1987年   57篇
  1986年   34篇
  1985年   62篇
  1984年   42篇
  1983年   23篇
  1982年   35篇
  1981年   29篇
  1980年   37篇
  1979年   35篇
  1978年   29篇
  1977年   24篇
  1976年   24篇
  1975年   10篇
  1974年   11篇
排序方式: 共有5547条查询结果,搜索用时 15 毫秒
1.
2.
3.
张怡然 《天津护理》2022,30(5):556-559
目的:调查冠心病合并糖尿病患者护理依赖性情况,并分析其影响因素。方法:采用便利抽样法选择142例冠心病合并糖尿病患者为研究对象,使用护理依赖性量表(CDS)对患者的护理依赖性进行调查。结果:冠心病合并糖尿病患者CDS 总分为(44.85 ± 16.47)分,护理依赖发生率为 64.79%。文化程度、服药种类、是否了解病情、是否合并其他慢性疾病、是否行介入手术影响患者的护理依赖程度(P<0.05)。结论:冠心病合并糖尿病患者的护理依赖性发生率偏高,在护理过程中多关注文化程度低、服药种类多、不了解病情、合并其他慢性疾病及接受介入手术治疗的患者,制定合理的护理计划,实行有效的护理干预措施,以降低冠心病合并糖尿病患者的护理依赖性。  相似文献   
4.
目的:探讨慢性酒依赖(CAD)患者失匹配负波(MMN)改变与其人格特征的关系。方法:采用改良的艾森克人格问卷(EPQ-R)对33例CAD患者(CAD组)和33名健康对照志愿者(对照组)进行评估,同时进行事件相关电位(ERP)检测,分析CAD患者MMN指标与其人格特征的关系。结果:CAD组EPQ-R中神经质(N)、精神质(P)和掩饰性(L)维度评分显著高于对照组(P<0.05或P<0.01);ERP各通道MMN潜伏期显著延长(P<0.05或P<0.01)。相关分析显示,CAD患者MMN指标与其人口学资料及人格特征无相关性。结论:CAD患者具有神经质、精神质的人格特征,其MMN潜伏期延长,但MMN改变与其人格特征无相关性。  相似文献   
5.
《Clinical lung cancer》2020,21(2):171-176
BackgroundPatients with lung cancer continue to smoke owing to complex factors. Failure to quit smoking (defined as nicotine dependence) is significantly associated with genetic status. This study aimed to investigate the relationship between polymorphisms in nicotine dependence genes and smoking status after the diagnosis of lung cancer.Patients and MethodsA total of 240 patients with lung cancer were included from July 2017 to March 2018. According to the actual smoking condition after lung cancer diagnosis, eligible patients were divided into 3 groups: the never-smoking group, the failure to quit smoking group, and the successful smoking cessation group. Fagerstrom Test for Nicotine Dependence scores were used to evaluate the smoking status of each group. Three nicotine-dependent genes with 6 loci were detected.ResultsAmong the 240 patients, 86 were never-smokers, 51 failed to quit smoking, and 104 successfully quit smoking. The initial age of smoking in the failure to quit smoking group was significantly younger than those in the successful smoking cessation group (P = .001). There was a significant difference in the GG and AG and AA genotype distributions of CHRNA3 (rs578776) among the 3 groups (P = .003). There was also a significant difference in the distribution of CHRNA4 (rs2229959) genotypes among the 3 groups (P = .003). However, there was no significant difference in the genotype distribution of CHRNA5 (rs588765) among the 3 groups (P = .277).ConclusionsGene polymorphisms of CHRNA3 (rs578776) and CHRNA4 (rs1044396 and rs2229959) were associated with the success of smoking cessation after the diagnosis of lung cancer, which should be considered in the management of smoking cessation after patients are diagnosed with lung cancer.  相似文献   
6.
The frequently applied narrow and non-standard transverse dose profiles of intensity modulated photon-beam radiotherapy, lacking lateral secondary electron equilibrium, require the use of high-resolution dosimetry detectors, and small air-filled detectors are recommended as the reference detectors for cross-calibration of the high-resolution detectors. The present study focuses on the dosimetric properties of a novel cylindrical ionization chamber, the PTW Semiflex 3D 31021. The chamber's effective point of measurement was found to lie at (0.41 ± 0.04) r downstream the tip of the inner surface of the spherical front wall in the axial orientation and (0.46 ± 0.04) r upstream the chamber axis in the radial orientation. Due to its symmetrical design, the sigma values of its lateral dose response functions for all chamber's orientations are the same (2.10 ± 0.05 mm). The polarity correction factors obtained in this work do not exceed 0.1% and the saturation correction factor was below 1% up to a dose-per-pulse value of 0.956 mGy. The radiation quality correction factor kQ of the chamber as a function of the tissue-phantom-ratio, TPR20,10, has been calculated by Monte Carlo simulation and has been determined experimentally at the German Metrology Institute (Physikalisch-Technische Bundesanstalt, PTB). The values of the non-reference condition correction factor kNR have been Monte-Carlo-calculated for use of the chamber at various depths and field sizes.  相似文献   
7.
IntroductionComputed tomography (CT) numbers are used in radiological diagnosis, attenuation correction and radiotherapy treatment planning. Modern CT scanners use iterative reconstruction methods instead of the traditional filtered back projection (FBP). Hence, the investigation of CT number accuracy with image reconstruction techniques and X-ray tube potential (kVp) used in CT is warranted. The aim of this study is to evaluate the effect of Sinogram Affirmed Iterative Reconstruction (SAFIRE) Technique and image acquisition at different tube potentials on CT numbers of different tissue equivalent materials.MethodsImages of the Computerised Imaging Reference System Model 062M Electron Density Phantom were acquired at different tube potentials and reconstructed using FBP and different strengths of SAFIRE. Average CT numbers, in circular regions of interest, and their standard deviations were used to investigate any dependence of CT numbers on tube potentials and/or image reconstruction technique using non-parametric statistical tests with p-values set at 0.05.ResultsStatistically significant differences in CT numbers were not observed (p > 0.091) between the different image reconstruction techniques. CT number of bone equivalent materials increased significantly (p < 0.015), by up to 400 Hounsfield Units, when tube potential was decreased. Such extent of CT number change over the tube potentials range used in this study may influence diagnostic outcomes in lung nodule, contrast enhanced and calcium score studies. For all other tissue equivalent materials, the CT number did not change significantly for different tube potentials. Linear relationship was observed between CT numbers and electron densities.ConclusionThe study concludes that the CT numbers of all tissues did not change significantly with image reconstruction methods. However, the CT numbers of bone equivalent materials increased with decreasing tube potentials, which may result in misrepresentation of clinical information obtained.Implications for practiceWhen CT images are used to extract quantitative parameters such as calcium score, to characterise lung nodules and contrast enhanced structures, the kVp used for image acquisition should be carefully selected to avoid any misrepresentation of clinical information.  相似文献   
8.
9.

Background

High alcohol intake is associated with increased mortality. We aimed to identify factors affecting mortality in people drinking extreme amounts of alcohol.

Methods

We obtained information from the UK Biobank on approximately 500,000 participants aged 40–70 years at baseline assessment in 2006–2010. Habitual alcohol intake, lifestyle and physiological data, laboratory test results, and hospital diagnoses and death certificate data (to June 2020) for 5136 men (2.20% of male participants) and 1504 women (0.60%) who reported consuming ≥80 or ≥50 g/day, respectively, were used in survival analysis.

Results

Mortality hazard ratios for these excessive drinkers, compared to all other participants, were 2.02 (95% CI 1.89–2.17) for all causes, 1.89 (1.69–2.12) for any cancer, 1.87 (1.61–2.17) for any circulatory disease, and 9.40 (7.00–12.64) for any liver disease. Liver disease diagnosis or abnormal liver function tests predicted not only deaths attributed to liver disease but also those from cancers or circulatory diseases. Mortality among excessive drinkers was also associated with quantitative alcohol intake; diagnosed alcohol dependence, harmful use, or withdrawal syndrome; and current smoking at assessment.

Conclusions

People with chronic excessive alcohol intake experience decreased average survival, but there is substantial variation in their mortality, with liver abnormality and alcohol dependence or other alcohol use disorders associated with a worse prognosis. Clinically, patients with these risk factors and high alcohol intake should be considered for early or intensive management. Research can usefully focus on the factors predisposing to dependence or liver abnormality.  相似文献   
10.
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