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   9589篇
  免费   697篇
  国内免费   210篇
耳鼻咽喉   1453篇
儿科学   224篇
妇产科学   134篇
基础医学   714篇
口腔科学   199篇
临床医学   1811篇
内科学   894篇
皮肤病学   79篇
神经病学   271篇
特种医学   1021篇
外科学   579篇
综合类   1043篇
一般理论   4篇
预防医学   1026篇
眼科学   99篇
药学   634篇
  9篇
中国医学   140篇
肿瘤学   162篇
  2024年   2篇
  2023年   127篇
  2022年   156篇
  2021年   420篇
  2020年   389篇
  2019年   387篇
  2018年   363篇
  2017年   347篇
  2016年   392篇
  2015年   356篇
  2014年   663篇
  2013年   770篇
  2012年   511篇
  2011年   532篇
  2010年   506篇
  2009年   498篇
  2008年   454篇
  2007年   485篇
  2006年   457篇
  2005年   350篇
  2004年   289篇
  2003年   271篇
  2002年   208篇
  2001年   209篇
  2000年   159篇
  1999年   152篇
  1998年   109篇
  1997年   107篇
  1996年   77篇
  1995年   64篇
  1994年   103篇
  1993年   56篇
  1992年   57篇
  1991年   41篇
  1990年   56篇
  1989年   39篇
  1988年   40篇
  1987年   28篇
  1986年   30篇
  1985年   42篇
  1984年   38篇
  1983年   28篇
  1982年   41篇
  1981年   19篇
  1980年   16篇
  1979年   13篇
  1978年   18篇
  1977年   6篇
  1976年   6篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
2.
PurposeTo compare the characteristics of polidocanol (POL) and ethanolamine oleate (EO) sclerosing foams produced by a Shirasu porous glass membrane (SPGM) device with those made using a 3-way stopcock (3WSC).Materials and MethodsFoam half-life times were measured in an ex-vivo benchtop study. Computed tomography (CT) images of each foam were obtained over the time course, and a CT texture analysis was conducted. The bubble size in each foam was measured by an optical microscope.ResultsMedian foam half-life times were longer in the SPGM group than in the 3WSC group (POL: 198 vs 166 s, P = .02; EO: 640 vs 391 s, P < .01). In the CT texture analysis, median standard deviation (SD) and entropy (randomness) were lower, and median energy (uniformity) and gray-level cooccurrence matrix (GLCM) homogeneity were higher in the SPGM group than in the 3WSC group (POL SD: at 30 s and 50–300 s; POL entropy: at 0–60 s; EO SD: at 0–600 s; EO entropy: at 0–460 s; POL energy: at 0–40 s; POL GLCM homogeneity: at 0–250 s; EO energy: at 0–360 s; EO GLCM homogeneity: at 0–480 s; all P < .05). Median bubble diameters in the SPGM group and in the 3WSC group were 69 and 83 μm (P < .01), respectively, in the POL foam; and 36 and 36 μm (P = .45), respectively, in the EO foam.ConclusionsPOL and EO foams had greater uniformity and longer foam half-life time when prepared with an SPGM device than with a 3WSC.  相似文献   
3.
4.
AimTo understand the impact of nurse-related information, through social media usage on undergraduate nursing students’ professional identity.BackgroundPrevious research has addressed professional knowledge and practice that affect the development of undergraduate nursing students’ professional identities. As an increasingly crucial factor in the internet age, social media needs to be explored in-depth for its influence on the professional identity in nursing.DesignSequential explanatory mixed method was used in this study.MethodsIn this quantitative study, participants (N = 698) completed an e-questionnaire survey between June and July of 2020. The relationship between main variables was analyzed by linear regression using SPSS 20.0. Then, face-to-face semi-structured and audio-recorded interviews were carried out among participants (N = 16) between January and March of 2021.ResultsThe quantitative findings indicated that the mean score of professional identity was 93.07 ± 11.96 in participants. The results of the linear regression showed that the year in school, whether nursing was the first choice, online time per day, frequency of reading official accounts related nursing on WeChat and appraisal of the online nurse-related information and so on explained 49.0 % of the variance in professional identity. Four major themes emerged from the qualitative study: 1) increased concern; 2) few and non-professional information; 3) encouraged by positive information; 4) limited impact of negative information.ConclusionsNurse-related information on social media has the potential to have an impact on undergraduate nursing students’ professional identity. Nursing educators should guide undergraduate nursing students to use social media appropriately and assist them in developing their professional identity with it.  相似文献   
5.
诊断抑郁症的传统方法是通过面对面的评估和交谈。但是,许多患有抑郁症的患者不愿意在早期阶段就医,从而使病情恶化。为了在早期判断抑郁症患者的情况,提出一种利用社交媒体文本信息的时间序列特征和多示例学习的检测模型,考虑到抑郁症状不会立即出现,所以时序样本的使用显得非常重要,因此使用无监督LSTM提取时间序列特征,训练分类器实现二值分类,并使用多示例学习模型来解决不平衡样本问题。首先采用朴素贝叶斯分类器、随机森林、多元社会网络学习和多式抑郁词典学习作为基准,随后利用具有无监督LSTM时间序列功能的多示例学习来更准确地检测抑郁症。在MDDL数据集的基础上,整理出200个调查对象合计7 946条推文信息,并按照训练测试比为8:2的实验得到结果如下:在准确率、精度,召回率和F1得分上分别达到75.0%、76.0%、73.0%、74.5%。结果表明,通过社交媒体中的文本数据,采用机器学习进行早期抑郁症检测是可行的。此外,通过大量的消融实验也证实,采用时间序列特征的方法要比传统的基准模型方法能够获得更好的性能。  相似文献   
6.
陈丹丹  万业达  何辉  刘妍 《天津医药》2022,50(9):980-983
目的 探讨超声造影判定甲状旁腺切除术加自体甲状旁腺异位移植术后移植物是否成活的价值。方法 收集因肾功能衰竭并发继发性甲状旁腺功能亢进而行甲状旁腺自体异位移植术的患者17例。每例患者于未行动静脉造瘘术的前臂皮下与脂肪之间移植4枚甲状旁腺组织,共68枚。在移植术后15~21 d进行超声造影检查,观察移植物的血供强化情况,估测移植后的甲状旁腺是否成活并具有分泌功能。按照移植物是否全部出现强化表现分为部分移植成功组与全部移植成功组,并以术后30 d双侧头静脉甲状旁腺激素水平对比判定移植物是否成活。结果 17例患者中,全部移植成功组8例,部分移植成功组9例,移植侧头静脉甲状旁腺激素水平高于非移植侧,全部移植成功组头静脉甲状旁腺激素水平高于部分移植成功组,差异有统计学意义(P<0.05)。结论 超声造影可以更准确、更有针对性及更早期地评价甲状旁腺自体异位移植的成活率。  相似文献   
7.
《Radiography》2022,28(3):718-724
IntroductionLiver cancer lesions on Computed Tomography (CT) withholds a great amount of data, which is not visible to the radiologists and radiographer. Radiomics features can be extracted from the lesions and used to train Machine Learning (ML) algorithms to predict between tumour and liver tissue. The purpose of this study was to investigate and classify Radiomics features extracted from liver tumours and normal liver tissue in a limited CT dataset.MethodsThe Liver Tumour Segmentation Benchmark (LiTS) dataset consisting of 131 CT scans of the liver with segmentations of tumour tissue and healthy liver was used to extract Radiomic features. Extracted Radiomic features included size, shape, and location extracted with morphological and statistical techniques according to the International Symposium on Biomedical Imaging manual. Relevant features was selected with chi2 correlation and principal component analysis (PCA) with tumour and healthy liver tissue as outcome according to a consensus between three experienced radiologists. Logistic regression, random forest and support vector machine was used to train and validate the dataset with a 10-fold cross-validation method and the Grid Search as hyper-parameter tuning. Performance was evaluated with sensitivity, specificity and accuracy.ResultsThe performance of the ML algorithms achieved sensitivities, specificities and accuracy ranging from 96.30% (95% CI: 81.03%–99.91%) to 100.00% (95% CI: 86.77%–100.00%), 91.30% (95% CI: 71.96%–98.93%) to 100.00% (95% CI: 83.89%–100.00%)and 94.00% (95% CI: 83.45%–98.75%) to 100.00% (95% CI: 92.45%–100.00%), respectively.ConclusionML algorithms classifies Radiomics features extracted from healthy liver and tumour tissue with perfect accuracy. The Radiomics signature allows for a prognostic biomarker for hepatic tumour screening on liver CT.Implications for practiceDifferentiation between tumour and liver tissue with Radiomics ML algorithms have the potential to increase the diagnostic accuracy, assist in the decision-making of supplementary multiphasic enhanced medical imaging, as well as for developing novel prognostic biomarkers for liver cancer patients.  相似文献   
8.
The purpose of this study was to investigate the association between habitual snoring (HS), middle ear disease (MED), and speech problems in children with cleft palate. This cross-sectional study included children aged 2.0–7.9 years with non-syndromic cleft palate anomalies. Parents completed the Pediatric Sleep Questionnaire and a questionnaire about MED. Audiograms and speech assessment were also conducted. Ninety-five children were enrolled; 15.2% of families reported HS, 97.6% MED, and 17.1% speech problems. HS (37.5% vs 10.3%, P = 0.007) and early episodes of MED (92.3% vs 58.2%, P = 0.021) were more likely to be reported for children with isolated cleft palate when compared to those with cleft lip and palate. Children with cleft lip and palate had a higher frequency of MED with effusion compared to those with Robin sequence (86.4% vs 57.1%, P = 0.049). The odds ratio for HS in children with ≥1 episode of MED in the last year was 7.37 (95% confidence interval 1.55–35.15, P = 0.012). There was a trend for children with speech problems reported by parents to have HS (30.8% vs 11.5%, P= 0.076). Anatomical factors play a role in the frequency of upper airway symptoms in children with cleft palate. A recent history of at least one episode of MED was associated with an increased frequency of HS.  相似文献   
9.
10.
The availability of human papillomavirus (HPV) vaccines and screening tests has raised the possibility of globally eliminating cervical cancer, which is caused by HPV. Cervical cancer is a very common malignancy worldwide, especially among deprived women. High vaccination coverage is key to the containment and eventual elimination of the infection. Public HPV vaccination programmes in Italy and Denmark were swiftly established and are among the most successful worldwide. Still, in both countries, it has been challenging to achieve and maintain the recommended coverage of > 80% in girls. In a well‐studied Italian region, vaccination coverage in girls at age 15 years (World Health Organization''s gold standard) reached 76% in 2015 but decreased to 69% in 2018, likely due to work overload in public immunization centres. In Denmark, doubts about safety and efficacy of the HPV vaccine generated a decline in coverage among girls age 12–17, from 80% in 2013 down to 37% in 2015, when remedial actions made it rise again. Insights from these two countries are shared to illustrate the importance of monitoring coverage in a digital vaccine registry and promptly reacting to misinformation about vaccination.

Abbreviations

CC
cervical cancer
FVG
Friuli Venezia Giulia
HICs
high‐income countries
HPV
human papillomavirus
LMICs
middle‐income countries
WHO
World Health Organization
  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