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   1132篇
  免费   116篇
  国内免费   16篇
耳鼻咽喉   17篇
儿科学   33篇
妇产科学   59篇
基础医学   117篇
口腔科学   29篇
临床医学   115篇
内科学   107篇
皮肤病学   2篇
神经病学   165篇
特种医学   27篇
外科学   195篇
综合类   101篇
预防医学   103篇
眼科学   53篇
药学   70篇
中国医学   22篇
肿瘤学   49篇
  2024年   1篇
  2023年   27篇
  2022年   30篇
  2021年   66篇
  2020年   77篇
  2019年   62篇
  2018年   55篇
  2017年   61篇
  2016年   62篇
  2015年   47篇
  2014年   84篇
  2013年   89篇
  2012年   71篇
  2011年   55篇
  2010年   45篇
  2009年   59篇
  2008年   56篇
  2007年   50篇
  2006年   42篇
  2005年   42篇
  2004年   19篇
  2003年   16篇
  2002年   19篇
  2001年   14篇
  2000年   14篇
  1999年   10篇
  1998年   8篇
  1997年   7篇
  1996年   5篇
  1995年   10篇
  1994年   5篇
  1993年   9篇
  1992年   3篇
  1991年   4篇
  1990年   3篇
  1989年   6篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   7篇
  1983年   2篇
  1982年   2篇
  1981年   6篇
  1980年   4篇
  1973年   1篇
  1965年   1篇
排序方式: 共有1264条查询结果,搜索用时 15 毫秒
1.
目的:探讨益生菌不同用药时机对妊娠合并糖尿病患者胰岛素抵抗及妊娠结局的影响。方法:选择2019年5月至2021年5月在衡水市妇幼保健院就建档分娩的妊娠合并糖尿病患者,分为对照组、孕早期组、孕中期组和孕晚期组,每组200例。对照组仅采用常规干预措施(未予以益生菌制剂),孕早期组、孕中期组和孕晚期组均予以双歧杆菌三联活菌肠溶胶囊420 mg,每日2次口服,疗程均为12周。比较4组患者分娩时血糖水平、糖化血红蛋白(HbA1c)、胰岛素抵抗指数(HOMA-IR)、血脂水平、产妇及新生儿不良妊娠结局等情况。结果:共纳入783例患者。孕早期组、孕中期组和孕晚期组患者分娩时血糖水平、HbA1c、HOMA-IR和血脂水平均优于对照组,孕中期组和孕晚期组优于孕早期组(P<0.05),而孕中期组和孕晚期组比较差异无统计学意义(P>0.05)。孕早期组、孕中期组和孕晚期组产妇及新生儿妊娠结局不良发生率均小于对照组,孕中期组和孕晚期组产妇及新生儿妊娠结局不良发生率均小于孕早期组,孕中期组早产和产后感染小于孕晚期组(P<0.05)。结论:益生菌不同用药时机对妊娠合并糖尿病患者胰岛素抵抗及妊娠结局存在一定差异,其中孕中期(孕14~16周)开始用药为最佳用药时机。  相似文献   
2.
Guidance for the timing of surgery following SARS-CoV-2 infection needed reassessment given widespread vaccination, less virulent variants, contemporary evidence and a need to increase access to safe surgery. We, therefore, updated previous recommendations to assist policymakers, administrative staff, clinicians and, most importantly, patients. Patients who develop symptoms of SARS-CoV-2 infection within 7 weeks of planned surgery, including on the day of surgery, should be screened for SARS-CoV-2. Elective surgery should not usually be undertaken within 2 weeks of diagnosis of SARS-CoV-2 infection. For patients who have recovered from SARS-CoV-2 infection and who are low risk or having low-risk surgery, most elective surgery can proceed 2 weeks following a SARS-CoV-2 positive test. For patients who are not low risk or having anything other than low-risk surgery between 2 and 7 weeks following infection, an individual risk assessment must be performed. This should consider: patient factors (age; comorbid and functional status); infection factors (severity; ongoing symptoms; vaccination); and surgical factors (clinical priority; risk of disease progression; grade of surgery). This assessment should include the use of an objective and validated risk prediction tool and shared decision-making, taking into account the patient's own attitude to risk. In most circumstances, surgery should proceed unless risk assessment indicates that the risk of proceeding exceeds the risk of delay. There is currently no evidence to support delaying surgery beyond 7 weeks for patients who have fully recovered from or have had mild SARS-CoV-2 infection.  相似文献   
3.
The impact of vaccination and new SARS-CoV-2 variants on peri-operative outcomes is unclear. We aimed to update previously published consensus recommendations on timing of elective surgery after SARS-CoV-2 infection to assist policymakers, administrative staff, clinicians and patients. The guidance remains that patients should avoid elective surgery within 7 weeks of infection, unless the benefits of doing so exceed the risk of waiting. We recommend individualised multidisciplinary risk assessment for patients requiring elective surgery within 7 weeks of SARS-CoV-2 infection. This should include baseline mortality risk calculation and assessment of risk modifiers (patient factors; SARS-CoV-2 infection; surgical factors). Asymptomatic SARS-CoV-2 infection with previous variants increased peri-operative mortality risk three-fold throughout the 6 weeks after infection, and assumptions that asymptomatic or mildly symptomatic omicron SARS-CoV-2 infection does not add risk are currently unfounded. Patients with persistent symptoms and those with moderate-to-severe COVID-19 may require a longer delay than 7 weeks. Elective surgery should not take place within 10 days of diagnosis of SARS-CoV-2 infection, predominantly because the patient may be infectious, which is a risk to surgical pathways, staff and other patients. We now emphasise that timing of surgery should include the assessment of baseline and increased risk, optimising vaccination and functional status, and shared decision-making. While these recommendations focus on the omicron variant and current evidence, the principles may also be of relevance to future variants. As further data emerge, these recommendations may be revised.  相似文献   
4.
《Clinical breast cancer》2020,20(5):390-394
BackgroundBreast cancer patients with triple-negative or human epidermal growth factor receptor 2 (HER2)-overexpressing phenotypes are recommended to receive chemotherapy for primary tumors greater than 1 cm regardless of nodal status. Neoadjuvant chemotherapy may eradicate subclinical nodal metastases and reduce the extent of axillary surgery performed.Patients and MethodsA query of the National Cancer Database Participant User File was performed for new cases of female breast cancer from 2012 to 2015. Inclusion criteria were clinical N0 status, receipt of chemotherapy, and receipt of axillary surgery. Exclusions included hormone-positive/HER2-negative tumors and/or distant metastatic disease. Subjects were divided into groups by receipt of neoadjuvant or adjuvant chemotherapy. The primary end point was the extent of axillary surgery, defined as sentinel lymph node biopsy alone or axillary lymph node dissection (ALND). Subgroup analyses were performed on the basis of tumor phenotype and surgery of the primary site.ResultsA total of 66,771 female patients were included, 15,967 of whom underwent neoadjuvant chemotherapy. ALND rates were higher in patients who received adjuvant chemotherapy (30.6% vs. 28.8%, P < .001). Among tumor phenotypes, the extent of axillary surgery was reduced most significantly for hormone-negative, HER2-positive disease (30.0% vs. 25.8%, P < .001). ALND rates were more substantially reduced for patients who underwent mastectomy (41.3% vs. 36.1%, P < .001) compared to partial mastectomy (21.8% vs. 20.1%, P = .002). Adjuvant chemotherapy was an independent predictor of ALND (odds ratio, 1.26; 95% confidence interval, 1.19-1.33).ConclusionNeoadjuvant chemotherapy reduces the extent of axillary surgery in clinically node-negative, nonluminal breast cancers.  相似文献   
5.
6.
Time sensitivity is affected by emotional stimuli such as fearful faces. The effect of threatening stimuli on time perception depends on numerous factors, including task type and duration range. We applied a two‐interval forced‐choice task using face stimuli to healthy volunteers to evaluate time perception and emotion interaction using functional magnetic resonance imaging. We conducted finite impulse response analysis to examine time series for the significantly activated brain areas and psycho‐physical interaction to investigate the connectivity between selected regions. Time perception engaged a right‐lateralised frontoparietal network, while a face discrimination task activated the amygdala and fusiform face area (FFA). No voxels were active with regard to the effect of expression (fearful versus neutral). In parallel with this, our behavioural results showed that attending to the fearful faces did not cause duration overestimation. Finally, connectivity of the amygdala and FFA to the middle frontal gyrus increased during the face processing condition compared to the timing task. Overall, our results suggest that the prefrontal–amygdala connectivity might be required for the emotional processing of facial stimuli. On the other hand, attentional load, task type and task difficulty are discussed as possible factors that influence the effects of emotion on time perception.  相似文献   
7.
8.
Beyond the classic sensory systems, the sense of time is most likely involved from foraging to navigation. As a prerequisite for assessing the role time is playing in different behavioral contexts, we further characterized the sense of time of a harbor seal in this study. Supra-second time intervals were presented to the seal in a temporal discrimination and a temporal bisection task. During temporal discrimination, the seal needed to discriminate between a standard time interval (STI) and a longer comparison interval. In the bisection task, the seal learnt to discriminate two STIs. Subsequently, it indicated its subjective perception of test time intervals as resembling either the short or long STI more. The seal, although unexperienced regarding timing experiments, learnt both tasks fast. Depending on task, time interval or duration ratio, it achieved a high temporal sensitivity with Weber fractions ranging from 0.11 to 0.26. In the bisection task, the prerequisites for the Scalar Expectancy Theory including a constant Weber fraction, the bisection point lying close to the geometric mean of the STIs, and no significant influence of the STI pair condition on the probability of a long response were met for STIs with a ratio of 1:2, but not with a ratio of 1:4. In conclusion, the harbor seal's sense of time allows precise and complex judgments of time intervals. Cross-species comparisons suggest that principles commonly found to govern timing performance can also be discerned in harbor seals.  相似文献   
9.
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