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   12706篇
  免费   1249篇
  国内免费   169篇
耳鼻咽喉   174篇
儿科学   331篇
妇产科学   133篇
基础医学   1122篇
口腔科学   274篇
临床医学   645篇
内科学   1249篇
皮肤病学   340篇
神经病学   610篇
特种医学   461篇
外科学   553篇
综合类   729篇
现状与发展   2篇
预防医学   4485篇
眼科学   129篇
药学   2204篇
  3篇
中国医学   84篇
肿瘤学   596篇
  2024年   5篇
  2023年   167篇
  2022年   212篇
  2021年   425篇
  2020年   522篇
  2019年   510篇
  2018年   454篇
  2017年   565篇
  2016年   542篇
  2015年   491篇
  2014年   752篇
  2013年   1230篇
  2012年   653篇
  2011年   756篇
  2010年   593篇
  2009年   588篇
  2008年   618篇
  2007年   565篇
  2006年   518篇
  2005年   440篇
  2004年   408篇
  2003年   320篇
  2002年   285篇
  2001年   254篇
  2000年   238篇
  1999年   160篇
  1998年   143篇
  1997年   105篇
  1996年   151篇
  1995年   150篇
  1994年   130篇
  1993年   123篇
  1992年   162篇
  1991年   117篇
  1990年   113篇
  1989年   92篇
  1988年   81篇
  1987年   66篇
  1986年   42篇
  1985年   73篇
  1984年   73篇
  1983年   37篇
  1982年   48篇
  1981年   37篇
  1980年   24篇
  1979年   26篇
  1978年   14篇
  1977年   14篇
  1976年   14篇
  1973年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
An accumulating body of evidence has associated exposure to greenspace with improved birth outcomes, including higher birth weight and lower risk of low birth weight; however, evidence on such association with in-utero fetal growth is scarce. We explored the influence of maternal exposure to residential greenspace and fetal growth in four INMA (Infancia y Medio Ambiente) Spanish birth cohorts (2003–2008), with 2,465 participants. Residential greenspace was characterised by the Normalised Difference Vegetation Index (NDVI) average across 100 m, 300 m, and 500 m buffers around the residence. Repeated ultrasound measurements of the abdominal circumference (AC), biparietal diameter (BPD), femur length (FL), and estimated fetal weight (EFW) were used. We created customised-generalised least squares models to evaluate associations of residential greenspace exposure on each fetal growth parameter, controlled for the relevant confounders. There were associations between the 500 m buffer and BPD, FL, and AC. We also found associations in the 300 m buffer and FL and AC. The associations in the 100 m buffer were null. Estimates were higher among participants with lower socioeconomic status. Mediation analyses found that air pollution might explain 15–37% of our associations. Mediation by physical activity was not observed. Greenspace exposure may be beneficial for fetal growth.  相似文献   
2.
3.
PurposeThis study aimed to identify the evidence in the scientific literature between exposure to surgical smoke and biological symptoms in healthcare professionals and patients.DesignA systematic review.MethodsElectronic databases were searched, including vivo observational and experimental studies published until August 2020 in Portuguese, English, Spanish and French.FindingsWe identified 13 studies, with a predominance of cross-sectional (6; 46.15%), experimental laboratory (4; 30.76%) and cohort (3; 23.07%) studies. The main manifestations identified were related to respiratory tract and headache. There was identification of histopathological changes in the nasal mucosa of healthcare professionals and the presence of toxic substances from smoke identified in the urine of patients and healthcare professionals.ConclusionThe scientific literature on the biological symptoms of surgical smoke is mainly composed of observational studies with a reduced sample size, thus constituting aspects which limit a broader and long-term understanding of the biological effects of surgical smoke exposure in healthcare professionals and patients.  相似文献   
4.
《Indian heart journal》2021,73(5):549-554
ObjectiveRobotically assisted PCI offers a great alternative to S–PCI. This has gained even more relevance during the COVID-19 pandemic era however safety of R–PCI compared to S–PCI has not been studied well. This study explores the safety and efficacy of robotically assisted PCI (R–PCI) compared to standard PCI (S–PCI) for the treatment of coronary artery disease (CAD).MethodsPubMed, Scopus, Ovid, and Google scholar databases were searched for studies comparing R–PCI to S–PCI. Outcomes included clinical success, procedure time, fluoroscopy time, contrast use and radiation exposure.ResultsTheauthors included 5 studies comprising 1555 patients in this meta-analysis. Clinical success was comparable in both arms (p = 0.91). Procedure time was significantly longer in R–PCI group (risk ratio: 5.52, 95% confidence interval: 1.85 to 9.91, p = 0.003). Compared to S–PCI, patients in R–PCI group had lower contrast use (meandifference: −19.88, 95% confidence interval: −21.43 to −18.33, p < 0.001), fluoroscopy time (mean difference:-1.82, 95% confidence interval: −3.64 to −0.00, p = 0.05) and radiation exposure (mean difference:-457.8, 95% confidence interval: −707.14 to −208.14, p < 0.001).ConclusionR–PCI can achieve similar success as S–PCI at the expense of longer procedural times. However, radiation exposure and contrast exposure were lower in the R–PCI arm.  相似文献   
5.
6.
BackgroundPrior reports demonstrate the expression of estrogen and progesterone receptors in high-grade gliomas (HGGs), but the relationship between hormone receptor-positive disease and risk of HHGs in patients with breast cancer (BC) remains uncharacterized.MethodsUsing the SEER 18 registries (2000–2017), we examined the temporal trend of the incidence of HGGs and BC. The standardized incidence ratio was calculated to assess the risk of subsequent HGG in BC patients.ResultsDuring the study period, the incidence of BC and HGGs remained comparable for men and women. Among 976,134 patients with BC, we found a decreased incidence of HGGs in females, but not in males. Female BC patients with hormone receptor-positive disease were at a lower risk of developing glioblastoma and anaplastic astrocytoma.ConclusionOur study findings allude to the protective role of hormone exposure in the development of HGGs, which may lead to the development of therapies targeting hormonal pathways.  相似文献   
7.
艾灸作为中医学最古老的疗法之一,作用多样,应用广泛,疗效显著。随着科技的发展,人们对灸法的认识逐渐深入,其中艾烟的相关研究也硕果累累,其安全性广受关注。通过对艾烟作用和安全性评价研究中取得的成果进行归纳分析,以期为艾灸临床安全应用提供指导。  相似文献   
8.
ObjectivesThe aim of this study was to retrospectively examine trends in percutaneous exposure incidences (PEIs) at the School of Dentistry (SoD) from 2009 to 2019 and to report on the underreporting rate of PEIs, current attitudes, and awareness of PEI safety protocols from clinical staff and students at the SoD in 2019.MethodsRetrospective data were collected from deidentified archival incident reports from 2009 to 2019 from the SoD's incident reporting system (UQSafe and Legacy Database). Additionally, cross-sectional data were collected via the validated Percutaneous Exposure Incident Questionnaires (PEIQ) completed by clinical staff and students of the SoD in 2019.ResultsFrom the archival data, the majority (79.9%) of the 618 reported PEIs involved students. Local anaesthetic-related procedures were the most common cause in the archival (31.5%) and survey data (23.7%), whereas the needle-prick was the most common causative instrument in both data sets. Additionally, the finger was the most common site of injury found in the archival (53.0%) and survey data (52.8%). From 345 responses to the survey, 42.1% of PEIs sustained were not reported.ConclusionsStudents were at a higher risk of sustaining a PEI than staff members between 2009 and 2019. The reported knowledge on PEI classification and preventative measures is inadequate, suggesting that further PEI education is necessary. The study provides evidence of the trends in PEIs as well as data on the attitudes and awareness of student and staff at a dental teaching faculty to support the development of PEI safety management protocols.  相似文献   
9.
目的 掌握江西省临床核医学应用频度和受检者的分布特点,估算2017年全省临床核医学应用频度。方法 对全省范围内开展临床核医学工作的各级医疗机构进行普查,以发放调查问卷的形式对样本医院进行应用频度调查与分析。结果 除正电子发射断层扫描(PET)检查男性多于女性外,其余临床核医学诊疗项目均为女性多于男性;全省临床核医学诊疗应用频度为0.67人次/千人口,其中诊断频度为0.58人次/千人口,治疗频度为0.09次/千人口。结论 与"九五"期间相比,江西省临床核医学应用频度迅猛发展,有必要进一步规范核医学诊疗工作,增强核医学工作人员的放射防护意识,促进核医学健康有序地发展。  相似文献   
10.
IntroductionSunlight exposure is the main source of vitamin D. Our aim was to describe both sun exposure and sun protection behaviour in a series of patients with inflammatory bowel disease (IBD), and to study their potential association with vitamin D concentration.Patients and methodsA cross sectional, observational study. The clinical-demographic variables were obtained via clinical interviews and medical history review. The sunlight exposure assessment was carried out using the Sun Exposure Questionnaire and the concentration of 25-hydroxy vitamin D (25OHD) was measured by an electro-chemiluminescence immunoassay. Questionnaires were conducted on quality of life, physical activity, weekly vitamin D intake and sun protection behaviour.Results149 patients were included. In 69% of patients, deficient or insufficient 25OHD values were recorded. 67% showed low sun exposure. A modest significant correlation was observed between the total score of the solar exposure questionnaire and the 25OHD concentration in the complete series (r = 0.226, P = .006) and in the summer (r = 0.274, P = .01). The sun protection behaviour questionnaire score did not influence the 25OHD concentration. In the multivariate analysis, only the presence of clinical activity was associated with low sun exposure (OR = 3.23).DiscussionSun exposure according to the questionnaire used was low, was associated with the presence of clinical activity and was weakly correlated with serum 25OHD concentration. More studies are needed to explore the use of individual questionnaires for sun exposure and its relationship with vitamin D in patients with IBD.  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