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   29323篇
  免费   1874篇
  国内免费   494篇
耳鼻咽喉   551篇
儿科学   5028篇
妇产科学   284篇
基础医学   2743篇
口腔科学   225篇
临床医学   2108篇
内科学   2585篇
皮肤病学   242篇
神经病学   1359篇
特种医学   504篇
外国民族医学   1篇
外科学   1670篇
综合类   2576篇
一般理论   2篇
预防医学   8941篇
眼科学   160篇
药学   1733篇
  4篇
中国医学   168篇
肿瘤学   807篇
  2023年   744篇
  2022年   1151篇
  2021年   1387篇
  2020年   1253篇
  2019年   1041篇
  2018年   1014篇
  2017年   1066篇
  2016年   1119篇
  2015年   1167篇
  2014年   1773篇
  2013年   2234篇
  2012年   1724篇
  2011年   1990篇
  2010年   1589篇
  2009年   1603篇
  2008年   1328篇
  2007年   1435篇
  2006年   1163篇
  2005年   1061篇
  2004年   905篇
  2003年   748篇
  2002年   616篇
  2001年   576篇
  2000年   480篇
  1999年   395篇
  1998年   293篇
  1997年   244篇
  1996年   180篇
  1995年   156篇
  1994年   126篇
  1993年   133篇
  1992年   104篇
  1991年   94篇
  1990年   76篇
  1989年   93篇
  1988年   90篇
  1987年   63篇
  1986年   73篇
  1985年   92篇
  1984年   58篇
  1983年   30篇
  1982年   29篇
  1981年   32篇
  1980年   24篇
  1979年   30篇
  1978年   22篇
  1977年   16篇
  1976年   18篇
  1975年   13篇
  1974年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
《Vaccine》2022,40(27):3721-3726
We initiated a randomized, placebo-controlled, phase 1/2 trial to evaluate the safety and immunogenicity of the S-268019-b recombinant protein vaccine, scheduled as 2 intramuscular injections given 21 days apart, in 60 randomized healthy Japanese adults. We evaluated 2 regimens of the S-910823 antigen (5 μg [n = 24] and 10 μg [n = 24]) with an oil-in-water emulsion formulation and compared against placebo (n = 12). Reactogenicity was mild in most participants. No serious adverse events were noted. For both regimens, vaccination resulted in robust IgG and neutralizing antibody production at days 36 and 50 and predominant T-helper 1-mediated immune reaction, as evident through antigen-specific polyfunctional CD4+ T-cell responses with IFN-γ, IL-2, and IL-4 production on spike protein peptides stimulation. Based on the interim analysis, the S-268019-b vaccine is safe, produces neutralizing antibodies titer comparable with that in convalescent serum from COVID-19-recovered patients. However, further evaluation of the vaccine in a large clinical trial is warranted.  相似文献   
2.
《Value in health》2022,25(8):1290-1297
ObjectivesThe COVID-19 pandemic forms an unprecedented public health, economic, and social crisis. Uptake of vaccination is critical for controlling the pandemic. Nevertheless, vaccination hesitancy is considerable, requiring policies to promote uptake. We investigate Dutch citizens’ preferences for policies that aim to promote vaccination through facilitating choice of vaccination, profiling it as the norm, making vaccination more attractive through rewards, or punishing people who reject vaccination.MethodsWe conducted a discrete choice experiment in which 747 respondents were asked to choose between policies to promote vaccination uptake and their impacts on the number of deaths, people with permanent health problems, households with income loss, and a tax increase.ResultsRespondents generally had a negative preference for policies that promote vaccination. They particularly disliked policies that punish those who reject the vaccine and were more favorable toward policies that reward vaccination, such as awarding additional rights to vaccinated individuals through vaccination passports. Respondents who reject vaccination were in general much more negative about the policy options than respondents who consider accepting the vaccine. Nevertheless, vaccination passports are supported by both respondents who accept the vaccine, those who reject vaccination, and those who are unsure about vaccination.ConclusionsThis study provides concrete directions for governments attempting to increase the vaccination uptake in ways that are supported by the public. Our results could encourage policy makers to focus on policy options that make vaccination easier and reward people who take the vaccine, as especially the implementation of vaccination passports was supported.  相似文献   
3.
4.
《Vaccine》2022,40(30):4038-4045
PurposeAs protection from COVID-19 following two doses of the BNT162b2 vaccine showed a time dependent waning, a third (booster) dose was administrated. This study aims to compare the antibody response following the third dose versus the second and to evaluate post-booster seroconversion.MethodsA prospective observational study conducted in Maccabi Healthcare Services. Serial SARS-CoV-2 Spike IgG tests, 1,2,3 and 6 months following the second vaccine dose and one month following the third were obtained. Neutralizing antibody levels were measured in a subset of participants. Per individual SARS-CoV-2 Spike IgG titer ratios were calculated one month after the booster administration compared to titers one month following the second dose and prior to booster.ResultsAmong 110 participants, 56 (51%) were women. Mean age was 61.7 ± 1.9 years and 66 (60%) were immunocompromised. One month after third dose, IgG titers were induced 7.83 (95 %CI 5.25–11.67) folds and 2.40 (95 %CI 1.90–3.03) folds compared to one month after the second, in the immunocompromised and immunocompetent groups, respectively. Of the 17 immunocompromised participants who were seronegative after the second dose, 4 (24%) became seropositive following the third. Comparing the titers prior to the third dose, an increase of 50.7 (95 %CI 32.5–79.1) fold in the immunocompromised group and 25.7 (95 %CI 19.1–34.7) fold in and immunocompetent group, was observed.ConclusionA third BNT162b2 vaccine elicited robust humoral response, superior to the response observed following the second, among immunocompetent and immunocompromised individuals.  相似文献   
5.
BackgroundDental caries is the most common chronic childhood disease. Past studies revealed that grandparents provide their grandchildren with cariogenic foods and beverages (eg, those with free sugars and/or modified starches). Qualitative research can help identify what drives this phenomenon.ObjectiveOur aim was to examine mothers’ explanations for why grandparents in north central and central Appalachia give their grandchildren cariogenic foods and beverages.DesignA qualitative study on children’s oral health in Pennsylvania and West Virginia from 2018 through 2020 was performed. In-person, semi-structured interviews were conducted. Qualitative data from interviews were recorded, transcribed, and then coded using NVivo. Data analysis for this study was performed using thematic analysis with iterative theme development.Participants/settingThe participants were 126 mothers of children aged 3-5 years from West Virginia (n = 66) and Pittsburgh, PA (n = 60).Main outcome measuresMothers’ perspectives about why grandparents give their grandchildren cariogenic foods and beverages were analyzed.ResultsIn the study sample, 85% of mothers (n = 107/126) named at least 1 of their children’s grandparents as a member of their social network responsible for their children’s oral health. From these interviews, 85% of mothers (n = 91/107) discussed that grandparents gave their grandchildren cariogenic foods and beverages. The mothers described the following 4 themes to explain why grandparents gave their grandchildren cariogenic foods and beverages: privilege of the grandparent role; responsibilities of the grandparent role; symbol of care and affection; and limited consideration or understanding of the detrimental impact.ConclusionsGrandparents play a role in giving their grandchildren cariogenic foods and beverages, which could potentially contribute to childhood caries. Research is needed to develop effective social interventions to help some grandparents understand the implications of a cariogenic diet on their grandchildren’s oral health and/or decrease their provision of cariogenic foods and beverages.  相似文献   
6.
《Molecular therapy》2022,30(5):1885-1896
  1. Download : Download high-res image (90KB)
  2. Download : Download full-size image
  相似文献   
7.
目的探讨采用基于"人工智能(AI)的骨龄辅助评价系统(上海初云医疗科技有限公司与四川大学华西第二医院合作开发)"(以下简称为AI系统)对完全性生长激素缺乏症(CGHD)患儿诊断及骨龄评价准确性。 方法选择2014年7月至2019年11月,于四川大学华西第二医院确诊的66例来自四川地区CGHD患儿为研究对象,纳入研究组。选择同期于病例收集医院儿童保健科进行骨龄测定的67例来自四川地区身高达标儿童作为对照,纳入对照组。对每例受试儿进行左手腕关节正位X射线摄片骨龄测定,由2位医师采用《TW2骨龄评分法中国未成年人南方标准》(以下简称为TW2CHN)》与《TW3骨龄评分法标准》(以下简称为TW3),盲法评价受试儿TW2CHN-桡、尺、掌指骨(RUS)与TW2CHN-腕骨(carpal)、TW2CHN-20、TW3-RUS及TW3-carpal骨龄(以下简称为5种传统骨龄),以及以同性别、年龄身高达标儿童5种传统骨龄为标准,计算受试儿5种传统骨龄百分位数。同时,采用AI系统分别对每例受试儿采取TW2CHN与TW3法,评价其AI-TW2CHN-RUS、AI-TW2CHN-carpal、AI-TW2CHN-20、AI-TW3-RUS及AI-TW3-carpal骨龄(以下简称为5种AI骨龄)及其相应百分位数。以上述5种传统骨龄+5种AI骨龄(以下简称为10种骨龄)相应的P50、P25、P10、P3值(统称为Pn值)作为诊断CGHD患儿临界值,分别计算其诊断CGHD患儿的敏感度、特异度、约登(Youden)指数、准确率、阳性似然比、阴性似然比、阳性预测值、阴性预测值。采用Kappa值评价2组受试儿5种传统骨龄百分位数与对应的5种AI骨龄百分位数评价结果的一致性,以及2位医师对2组受试儿TW2CHN-RUS骨龄百分位数评价结果一致性。绘制上述10种骨龄百分位数诊断CGHD患儿的受试者工作特征(ROC)曲线,并计算曲线下面积(AUC)。采用配对t检验,对2组受试儿TW2CHN骨龄与TW3骨龄进行比较。本研究遵循的程序符合2013年新修订的《世界医学协会赫尔辛基宣言》要求。2组受试儿年龄、性别构成比等一般临床资料比较,差异均无统计学意义(P>0.05)。 结果①采用10种骨龄的Pn值分别作为诊断CGHD临界值,对133例受试儿CGHD诊断结果显示,除了TW3-RUS骨龄中,以骨龄≤P10作为诊断CGHD患儿临界值时的诊断准确率最高(85.0%),TW2CHN-RUS、TW2CHN-carpal、TW2CHN-20、TW3-carpal、AI-TW2CHN-RUS、AI-TW2CHN-carpal、AI-TW2CHN-20、AI-TW3-carpal、AI-TW3-RUS骨龄中,均为以骨龄≤P25作为临界值时,对CGHD的诊断准确率最高,分别为81.9%、75.2%、88.0%、78.2%、75.2%、73.6%、81.2%、72.9%、78.9%。②一致性检验结果显示,2组受试儿TW2CHN-RUS与AI-TW2CHN-RUS、TW2CHN-carpal与AI-TW2CHN-carpal、TW2CHN-20与AI-TW2CHN-20、TW3-RUS与AI-TW3-RUS、TW3-carpal与AI-TW3-carpal骨龄百分位数评价结果均为中等一致性,Kappa值分别为0.445、0.578、0.570、0.446、0.430(均为P<0.001)。③对2位医师对2组受试儿TW2CHN-RUS骨龄百分位数评价结果进行一致性检验显示,其Kappa值为0.790(P<0.001),一致性较高。④绘制10种骨龄百分位数评价结果诊断CGHD的ROC曲线分析结果显示,TW2CHN-RUS、TW2CHN-carpal、TW2CHN-20、TW3-carpal、TW3-RUS、AI-TW2CHN-RUS、AI-TW2CHN-carpal、AI-TW2CHN-20、AI-TW3-carpal、AI-TW3-RUS骨龄百分位数诊断CGHD患儿的AUC分别为0.932、0.859、0.915、0.895、0.844、0.823、0.805、0.866、0.860、0.764(均为P<0.001)。⑤133例受试儿的TW3-RUS、TW3-carpal、AI-TW3-RUS、AI-TW3-carpal骨龄,均分别显著低于TW2CHN-RUS、TW2CHN-carpal、AI-TW2CHN-RUS、AI-TW2CHN-carpal骨龄,并且差异均有统计学意义(t=21.746、25.287、16.498、9.290,P<0.001)。 结论TW2CHN法、TW3法对CGHD患儿骨龄评价及诊断均有临床价值,TW2CHN-RUS骨龄对于CGDH患儿诊断效能高。四川地区儿童TW3骨龄较TW2CHN骨龄低,TW3法可能不完全适用于四川地区儿童骨龄评价。AI系统对于四川地区CGHD患儿骨龄评价结果与传统骨龄评价结果具有中等一致性,可为临床医师评价受试儿骨龄提供帮助。  相似文献   
8.
ObjectiveCoronavirus disease 2019 (COVID-19) vaccine mandates are being implemented in health systems across the United States, and the impact on the radiology department workforce and operations becuase of vaccine hesitancy among health care workers is currently unknown. This article discusses the potential impact of the COVID-19 vaccine mandate on a large multicenter radiology department as well as strategies to mitigate those effects.MethodsWeekly vaccine compliance data were obtained for employees across the entire health system from August 17, 2021, through September 13, 2021, and radiology department–specific data were extracted. Vaccine compliance data was mapped to specific radiology job titles and the five different hospital locations.ResultsA total of 6% of radiology department employees were not fully vaccine compliant by the initial deadline of September 10, 2021. MR technologists and radiology technology assistants had the highest initial rates of noncompliance of 37% and 38%, respectively. Vaccine noncompliance rates by the mandate deadline ranged from 0.5% to 7.0% at the five hospital sites. Only one hospital required a decrease in imaging hours of operation because of the vaccine mandate.ConclusionDespite initial concerns about the impact of vaccine mandate noncompliance on departmental operations, there was ultimately little effect because of improved vaccine compliance after the mandate. Understanding individual employee and locoregional differences in vaccine compliance can help leaders proactively develop mitigation strategies to manage this new challenge during the COVID-19 pandemic.  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