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   12454篇
  免费   740篇
  国内免费   115篇
耳鼻咽喉   58篇
儿科学   119篇
妇产科学   47篇
基础医学   643篇
口腔科学   109篇
临床医学   827篇
内科学   752篇
皮肤病学   106篇
神经病学   259篇
特种医学   142篇
外科学   355篇
综合类   2549篇
预防医学   3282篇
眼科学   57篇
药学   3224篇
  12篇
中国医学   584篇
肿瘤学   184篇
  2023年   104篇
  2022年   208篇
  2021年   265篇
  2020年   292篇
  2019年   251篇
  2018年   232篇
  2017年   213篇
  2016年   306篇
  2015年   368篇
  2014年   1097篇
  2013年   1241篇
  2012年   1440篇
  2011年   1360篇
  2010年   1182篇
  2009年   839篇
  2008年   717篇
  2007年   673篇
  2006年   499篇
  2005年   407篇
  2004年   263篇
  2003年   216篇
  2002年   173篇
  2001年   136篇
  2000年   116篇
  1999年   109篇
  1998年   77篇
  1997年   67篇
  1996年   52篇
  1995年   43篇
  1994年   39篇
  1993年   26篇
  1992年   23篇
  1991年   31篇
  1990年   12篇
  1989年   24篇
  1988年   17篇
  1987年   17篇
  1986年   10篇
  1985年   17篇
  1984年   16篇
  1982年   9篇
  1980年   9篇
  1979年   9篇
  1975年   10篇
  1974年   11篇
  1973年   19篇
  1972年   8篇
  1971年   10篇
  1970年   10篇
  1969年   6篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ObjectiveTo observe the relationship between the different stages of type 2 diabetes mellitus (T2DM) and the intestinal flora and verify its underlying mechanism.MethodsT2DM rats were generated by high-fat diet (HFD) combined with intraperitoneal streptozotocin (STZ) injection. The rats were divided into four groups: the control group (fed with normal feed for 1 month), the HFD group (fed with HFD for 1 month), the T2DM group (HFD combined with STZ and blood glucose ≥11.1 mM), and the unformed T2DM model (Un-mod) group (HFD combined with STZ and blood glucose <11.1 mM). Feces were collected, and bacterial communities in the fecal samples were analyzed by 16S rRNA gene sequencing. The content of short-chain fatty acids (SCFAs) in feces was measured by gas chromatography. Western blot and quantitative real-time polymerase chain reaction were used to detect the expression of G protein-coupled receptor 41 (GPR41) and GPR43.ResultsAt different stages of T2DM, the intestinal flora and SCFAs content of rats were significantly decreased (all P < .05). Our results indicated that g__Prevotella had a significant negative correlation, and g__Ruminococcus_torques_group and g__lachnoclastic had a significant positive correlation with blood glucose. The content of SCFAs, in particular acetate and butyrate, in rat feces of different stages of T2DM were significantly reduced, as well as GPR41 and GPR43 expression. The results in the Un-mod group were similar to the T2DM group, and the expression of GPR41 and GPR43 proteins were significantly higher than those in the T2DM group (both P < .001).ConclusionThe intestinal flora–SCFAs–GPR41/GPR43 network may be important in the development of T2DM. Decreasing blood glucose levels by regulating the intestinal flora may become a new therapeutic strategy for T2DM, which has very important clinical and social values.  相似文献   
2.
目的 建立蒙药绿松石的质量标准。方法 收集不同产地绿松石,共10批。观察绿松石样品和粉末的性状并进行理化鉴别;按2020年版《中国药典》(四部)通则方法测定绿松石样品中水分、浸出物含量;采用原子吸收光谱法测定绿松石样品铜元素含量。结果 绿松石为不规则、周围带有黑石的块状物,表面蓝绿色,体重,质硬脆,难砸碎,断面呈贝壳状,蜡样光泽,粉末呈灰绿色,无臭,味淡;理化鉴别结果显示,呈铜盐反应;10批次样品中水分含量为0.41%-3.94%(SD=1.37%),浸出物含量为0.21%-0.81%(SD=0.21%),铜元素含量为3.03%-4.63%(SD=0.63%)。结论 初步拟定绿松石中水分含量不得超多5.0%、浸出物含量不得低于0.10%,铜元素含量应为2.60%-4.84%,制定的标准可用于蒙药材绿松石的质量控制。  相似文献   
3.
目的 调查安徽省4所综合医院临床护士的营养护理能力,并分析其影响因素,为提高临床护士营养护理能力提供理论依据。方法 采用便利抽样法,2021年1月—2月应用一般资料问卷、临床护士营养护理能力量表对安徽省北部、中部、南部4所综合性医院的863名临床护士进行横断面调查。通过多元线性逐步回归分析临床护士营养护理能力的影响因素。结果 共回收有效问卷762份,临床护士营养护理能力总分为(235.16±44.02)分,条目得分为(3.73±0.70)分,其中营养专业知识维度和临床营养评估能力维度得分较低。多元线性逐步回归分析结果显示,工作年限、科室、定期接受营养护理督查、在校学习营养课、参加营养学习班、定期参加营养业务学习是临床护士营养护理能力的影响因素(P<0.05)。 结论 临床护士营养护理能力有待提高,护理管理者应重视对临床护士进行营养相关教育及培训,强化营养专业知识和临床营养评估能力,完善定期检查与考核机制,以提高临床护士的营养护理能力。  相似文献   
4.
PurposeTo investigate the reproducibility of diffusion-weighted (DW) MRI and 18F-Fluorodeoxyglucose (18F-FDG)-Positron emission tomography/CT (PET/CT) in monitoring response to neoadjuvant chemotherapy in epithelial ovarian cancer.Materials and methodsTen women (median age, 67 years; range: 41.8–77.3 years) with stage IIIC-IV epithelial ovarian cancers were included in this prospective trial (NCT02792959) between 2014 and 2016. All underwent initial laparoscopic staging, four cycles of carboplatine-paclitaxel-based chemotherapy and interval debulking surgery. PET/CT and DW-MRI were performed at baseline (C0), after one cycle (C1) and before surgery (C4). Two nuclear physicians and two radiologists assessed five anatomic sites for the presence of ≥ 1 lesion. Target lesions in each site were defined and their apparent diffusion coefficient (ADC), maximal standardized uptake value (SUV-max), SUV-mean, SUL-peak, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were monitored (i.e., 10 patients × 5 sites × 3 time-points). Their relative early and late changes were calculated. Intra/inter-observer reproducibilities of qualitative and quantitative analysis were estimated with Kappa and intra-class correlation coefficients (ICCs).ResultsFor both modalities, inter- and intra-observer agreement percentages were excellent for initial staging but declined later for DW-MRI, leading to lower Kappa values for inter- and intra-observer variability (0.949 and 1 at C0, vs. 0.633 and 0.643 at C4, respectively) while Kappa values remained > 0.8 for PET/CT. Inter- and intra-observer ICCs were > 0.75 for SUV-max, SUL-peak, SUV-mean and their change regardless the time-point. ADC showed lower ICCs (range: 0.013–0.811). ANOVA found significant influences of the evaluation time, the measurement used (ADC, SUV-max, SUV-mean, SUV-max, SUL-peak, MTV or TLG) and their interaction on ICC values (P = 0.0023, P< 0.0001 and P =0.0028, respectively).ConclusionWhile both modalities demonstrated high reproducibility at baseline, only SUV-max, SUL-peak, SUV-mean and their changes maintained high reproducibility during chemotherapy.  相似文献   
5.
6.
《Indian heart journal》2022,74(4):302-306
BackgroundThe alarming rise in prevalence of hypertension warrants psychosocial methods supplementing pharmacotherapy for better management and prevention of cardiac emergencies. The objective of the study was to assess the differential impact of the form and frequency of knowledge intervention on management of primary hypertension.Materials and methodThe study was conducted on 256 hypertensive patients recruited through purposive sampling at health centers in Hyderabad, India. Pretest post-test control group quasi-experimental design was adopted for the study. There were two forms of the knowledge intervention, namely ‘Direct Interaction’ and ‘Audio-Visual’. Each form was presented in two frequencies namely ‘single exposure’ and ‘double exposure’. The four groups were labelled as Direct Intervention Single (DIS), Direct Intervention Double (DID), Audio-Visual Single (AVS) and Audio-Visual Double (AVD). Adherence and management of hypertension were assessed at baseline and six weeks post experiment. Analysis of Covariance (ANCOVA) was applied using IBM SPSS Statistics version 20.ResultsANCOVA followed by Bonferroni Multiple Group Comparison Test revealed significant differences between the four intervention groups and control group on adherence (p< .001). In case of hypertension management significant differences were observed between Control group and DIS, DID (p < .001), Control and AVS (p < .01). Control group did not differ from AVD.ConclusionThere was a positive impact of Knowledge Intervention on adherence and management of hypertension. Double exposure in audio visual form was counterproductive in hypertension management.  相似文献   
7.
《Radiography》2022,28(2):518-523
IntroductionSelection of optimal image acquisition protocols in medical imaging remains a grey area, the superimposed use of the Likert scale in radiological image quality evaluations creates an additional challenge for the statistical analysis of image quality data.Using a simulation study, we have trialled a novel approach to analysing radiological image quality Likert scale data.MethodsA simulation study was undertaken where simulated datasets were generated based on the distribution of Likert scale values according to varying image acquisition protocols from a real dataset. Simulated Likert scale values were pooled in four different ways; the mean, median, mode and the summation of patient Likert scale values of which the total was assigned a categorical Likert scale value. Estimates of bias, MAPE and RMSPE were then calculated for all four pooling approaches to determine which method most accurately represented an expert's opinion.ResultsWhen compared to an expert's opinion, the method of summation and categorisation of Likert scale values was most accurate 49 times out of the 114 (43.0%) tests. The mean 28 times out of 114 (24.6%), the median 23 times out of 114 (20.2%) and the mode 17 times out of 114 (14.9%).ConclusionWe conclude that our method of summation and categorisation of Likert scale values is most often the best representation of the simulated data compared to the expert's opinion.Implications for practiceThere is scope to reproduce this simulation study with multiple observers to reflect clinical reality more accurately with the dynamic nature of multiple observers. This also prompts future investigation into other anatomical areas, to see if the same methods produce similar results.  相似文献   
8.
9.
The pituitary tumor-transforming gene 1 (PTTG1), also known as Securin, is considered an oncogene. This study aimed to investigate the role of PTTG1 in clear cell renal cell carcinoma (ccRCC) using in silico bioinformatics approaches. A pan-cancer analysis using The Cancer Genome Atlas (TCGA) data indicated that among all cancer types copy number amplification of PTTG1 gene was most frequently found in ccRCC. However, amplification of PTTG1 gene copy number did not correlate with the increase of mRNA level in ccRCC, and did not predict the patients' overall survival. Instead, ccRCC was correlated with overexpression of PTTG1 mRNA, and its expression level was stage-dependent increased in cancer patients. An outlier analysis using the Oncomine database suggested that PTTG1 mRNA expression served as a good biomarker for ccRCC. Pathway analysis for upregulated genes enriched in PTTG1-high expressing ccRCC patients found that PTTG1 overexpression was associated with mitotic defects. Mining drug sensitivity data using the Cancer Therapeutics Response Portal (CTRP) discovered that PTTG1-high expressing ccRCC cell lines were susceptible to a Rac1 (Ras-related C3 botulinum toxin substrate 1) inhibitor NSC23766. Therefore, this study provides an in silico insight into the role of PTTG1 in ccRCC, and repurposes the Rac1 inhibitor NSC23766 for treating PTTG1-high expressing ccRCC.  相似文献   
10.

Objectives

We examined the association between three inflammatory markers (Interleukin (IL)-6, C-reactive protein (CRP), tumor necrosis factor (TNF)-α) and incident lung cancer using baseline, updated, and averaged inflammatory measures in older adults.

Methods

We fitted multivariable Cox models to assess whether circulating levels of inflammation markers were associated with incident lung cancers in the Health Aging, Body and Composition (HealthABC) prospective cohort of 3075 older adults aged 70–79?years at baseline. IL-6 and CRP were measured biennially, whereas TNF-α was measured at baseline.

Results

Baseline levels of IL-6 were significantly associated with incident lung cancer risk in a model that adjusted for age, gender, race, and site (Model 1) (Hazard RatioT3 vs. T1: 3.34, 95% Confidence Interval: 1.91, 5.85) and in a model adjusted for health factors linked to chronic inflammation (Model 2) (HR T3 vs. T1: 2.57, 95% CI: 1.41, 4.65). The associations observed in time-updated IL-6 (HR T3 vs. T1: 2.47, 95% CI: 1.43, 4.28), cumulatively averaged IL-6 (HR T3 vs. T1: 2.47, 95% CI: 1.43, 4.35), and baseline CRP levels (HR T3 vs. T1: 1.85, 95% CI: 1.11, 3.08) with incident lung cancer in Model 1 were not statistically significant in Model 2.

Conclusions

Baseline CRP and IL-6 levels were associated with increased risk of lung cancer in Model 1 and both models, respectively. Chronic IL-6 inflammation, as quantified by repeated measures was associated with incident lung cancer in Model 1, but not Model 2. Further research is needed to understand the role of CRP and IL-6 in lung carcinogenesis.  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