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   6478篇
  免费   435篇
  国内免费   31篇
耳鼻咽喉   36篇
儿科学   234篇
妇产科学   147篇
基础医学   866篇
口腔科学   119篇
临床医学   596篇
内科学   1409篇
皮肤病学   114篇
神经病学   647篇
特种医学   137篇
外国民族医学   1篇
外科学   631篇
综合类   67篇
一般理论   4篇
预防医学   718篇
眼科学   81篇
药学   447篇
中国医学   20篇
肿瘤学   670篇
  2024年   7篇
  2023年   83篇
  2022年   168篇
  2021年   281篇
  2020年   190篇
  2019年   221篇
  2018年   259篇
  2017年   196篇
  2016年   218篇
  2015年   201篇
  2014年   308篇
  2013年   344篇
  2012年   621篇
  2011年   643篇
  2010年   342篇
  2009年   271篇
  2008年   388篇
  2007年   419篇
  2006年   381篇
  2005年   367篇
  2004年   293篇
  2003年   246篇
  2002年   208篇
  2001年   28篇
  2000年   13篇
  1999年   20篇
  1998年   49篇
  1997年   28篇
  1996年   21篇
  1995年   19篇
  1994年   24篇
  1993年   9篇
  1992年   7篇
  1991年   8篇
  1990年   7篇
  1989年   7篇
  1988年   5篇
  1987年   8篇
  1986年   3篇
  1985年   4篇
  1984年   5篇
  1983年   3篇
  1982年   8篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1969年   1篇
排序方式: 共有6944条查询结果,搜索用时 0 毫秒
41.
Cerebral blood flow is a finely tuned process dependent on coordinated changes in arterial tone. These changes are strongly tied to smooth muscle membrane potential and inwardly rectifying K+ (KIR) channels are thought to be a key determinant. To elucidate the role of KIR2.1 in cerebral arterial tone development, this study examined the electrical and functional properties of cells, vessels and living tissue from tamoxifen-induced smooth muscle cell (SMC)-specific KIR2.1 knockout mice. Patch-clamp electrophysiology revealed a robust Ba2+-sensitive inwardly rectifying K+ current in cerebral arterial myocytes irrespective of KIR2.1 knockout. Immunolabeling clarified that KIR2.1 expression was low in SMCs while KIR2.2 labeling was remarkably abundant at the membrane. In alignment with these observations, pressure myography revealed that the myogenic response and K+-induced dilation were intact in cerebral arteries post knockout. At the whole organ level, this translated to a maintenance of brain perfusion in SMC KIR2.1−/− mice, as assessed with arterial spin-labeling MRI. We confirmed these findings in superior epigastric arteries and implicated KIR2.2 as more functionally relevant in SMCs. Together, these results suggest that subunits other than KIR2.1 play a significant role in setting native current in SMCs and driving arterial tone.  相似文献   
42.
43.
Background

Recently developed convolutional neural network (CNN) models determine bone age more accurately than radiologists.

Objective

The purpose of this study was to determine whether a CNN and radiologists can accurately predict bone age from radiographs using only the index finger rather than the whole hand.

Materials and methods

We used a public anonymized dataset provided by the Radiological Society of North America (RSNA) pediatric bone age challenge. The dataset contains 12,611 hand radiographs for training and 200 radiographs for testing. The index finger was cropped from these images to create a second dataset. Separate CNN models were trained using the whole-hand radiographs and the cropped second-digit dataset using the consensus ground truth provided by the RSNA bone age challenge. Bone age determination using both models was compared with ground truth as provided by the RSNA dataset. Separately, three pediatric radiologists determined bone age from the whole-hand and index-finger radiographs, and the consensus was compared to the ground truth and CNN-model-determined bone ages.

Results

The mean absolute difference between the ground truth and CNN bone age for whole-hand and index-finger was similar (4.7 months vs. 5.1 months, P=0.14), and both values were significantly smaller than that for radiologist bone age determination from the single-finger radiographs (8.0 months, P<0.0001).

Conclusion

CNN-model-determined bone ages from index-finger radiographs are similar to whole-hand bone age interpreted by radiologists in the dataset, as well as a model trained on the whole-hand radiograph. In addition, the index-finger model performed better than the ground truth compared to subspecialty trained pediatric radiologists also using only the index finger to determine bone age. The radiologist interpreting bone age can use the second digit as a reliable starting point in their search pattern.

  相似文献   
44.
The call to address anti-Black racism in workplaces resonates across several organizations and institutions in Canada. But specifically, the coronavirus disease 2019 pandemic shed further light on how health inequities negatively impact the Black community. After conducting a literature review of the experiences of Black nurses in Canada, a deeper understanding of their plight was gained. In healthcare, the findings from the Black Nurses' Task Force report conclude that anti-Black racist practices are pervasive in nursing, and there remains a paucity of research in this area. This study builds off the report by exploring how Black nurses experience anti-Black racism while working in Canada's healthcare system. Inspired by critical race theory and Black feminist thought, an exploratory qualitative research study was conducted, using semistructured interviews to gather data. The study concludes that Black nurses experience anti-Black racism within the workplace, and it manifests itself through some of the attitudes of colleagues, patients, and nurses in leadership roles. Despite policies and statements that were in place to protect them, anti-Black racism continues to occur systematically. The findings point to the need for change in the overall workplace culture, which includes a fair representation of Black nurses in leadership roles, further research to identify best practices for tackling anti-Black racism within Canada's healthcare system, and mandatory training on anti-Black racism for healthcare leaders, educators, and service providers.  相似文献   
45.
The treatment of patients with early stage breast cancer has changed in recent years due to the introduction of pembrolizumab, olaparib, and abemaciclib. These and other drugs with the same class of active ingredient are currently in trial for various indications. This review article summarizes the latest results that have either been presented at major conferences such as the ESMO 2022 or published recently in international journals. This includes reports on newly discovered breast cancer genes, atezolizumab in neoadjuvant therapy in HER2-positive patients, long-term data from the APHINITY study, and on how preoperative peritumoral application of local anesthetics can influence the prognosis. We also present solid data on dynamic Ki-67 from the ADAPT studies.Key words: breast cancer, surgery, chemotherapy, therapy standard  相似文献   
46.
The objective of this study was to explore the effect of COVID-19 and Ramadan on physical activity (PA) and burnout in teachers and the relationship between them. A total of 57 secondary school teachers from public education centers participated in the present study. They were aged between 29 and 52 years. To determine the effect of Ramadan and COVID-19 on PA and burnout, participants completed the online questionnaires before COVID-19, one week before Ramadan and during the second week of Ramadan. The International Physical Activity Questionnaire-BREF and the Maslach Burnout Inventory-Human Services Survey were used to assess PA intensities and burnout, respectively. The data revealed that total PA (p < 0.001, p < 0.05, respectively) vigorous metabolic equivalent of task (MET) (p < 0.001, p < 0.05, respectively), moderate MET (p < 0.001, p < 0.01, respectively) were higher before COVID-19 and before Ramadan than during Ramadan. Regarding burnout subscales, emotional exhaustion (p < 0.001, p < 0.01, respectively) was higher before Ramadan than before COVID-19 and during Ramadan. A lower personal accomplishment was reported before Ramadan than before COVID-19 and during Ramadan (both p < 0.05). In addition, low to high correlations were observed between PA intensities and burnout subscales, except for the correlation between depersonalization and all PA intensities. In conclusion, Ramadan intermittent fasting along with PA was highly recommended for teachers and the general population to improve positive emotions and general health.  相似文献   
47.

Background  

Food behaviours, attitudes, environments and knowledge are relevant to professionals in childhood obesity prevention, as are dietary patterns which promote positive energy balance. There is a lack of valid and reliable tools to measure these parameters. The aim of this study was to determine the reliability and relative validity of a child nutrition questionnaire assessing all of these parameters, used in the evaluation of a community-based childhood obesity prevention project.  相似文献   
48.
Fructose intolerance (FI) is a widespread non-genetic condition in which the incomplete absorption of fructose leads to gastro-intestinal disorders. The crucial role of microbial dysbiosis on the onset of these intolerance symptoms together with their persistence under free fructose diets are driving the scientific community towards the use of probiotics as a novel therapeutic approach. In this study, we evaluated the prevalence of FI in a cohort composed of Romanian adults with Functional Grastrointestinal Disorders (FGIDs) and the effectiveness of treatment based on the probiotic formulation EQBIOTA® (Lactiplantibacillus plantarum CECT 7484 and 7485 and Pediococcus acidilactici CECT 7483). We evaluated the impact of a 30-day treatment both on FI subjects and healthy volunteers. The gastrointestinal symptoms and fecal volatile metabolome were evaluated. A statistically significant improvement of symptoms (i.e., bloating, and abdominal pain) was reported in FI patient after treatment. On the other hand, at the baseline, the content of volatile metabolites was heterogeneously distributed between the two study arms, whereas the treatment led differences to decrease. From our analysis, how some metabolomics compounds were correlated with the improvement and worsening of clinical symptoms clearly emerged. Preliminary observations suggested how the improvement of gastrointestinal symptoms could be induced by the increase of anti-inflammatory and protective substrates. A deeper investigation in a larger patient cohort subjected to a prolonged treatment would allow a more comprehensive evaluation of the probiotic treatment effects.  相似文献   
49.
50.
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