全文获取类型
收费全文 | 6610篇 |
免费 | 348篇 |
国内免费 | 100篇 |
专业分类
耳鼻咽喉 | 36篇 |
儿科学 | 141篇 |
妇产科学 | 61篇 |
基础医学 | 493篇 |
口腔科学 | 36篇 |
临床医学 | 235篇 |
内科学 | 765篇 |
皮肤病学 | 32篇 |
神经病学 | 202篇 |
特种医学 | 89篇 |
外科学 | 96篇 |
综合类 | 473篇 |
预防医学 | 3318篇 |
眼科学 | 20篇 |
药学 | 838篇 |
4篇 | |
中国医学 | 54篇 |
肿瘤学 | 165篇 |
出版年
2023年 | 80篇 |
2022年 | 165篇 |
2021年 | 199篇 |
2020年 | 194篇 |
2019年 | 223篇 |
2018年 | 204篇 |
2017年 | 197篇 |
2016年 | 225篇 |
2015年 | 223篇 |
2014年 | 340篇 |
2013年 | 557篇 |
2012年 | 316篇 |
2011年 | 446篇 |
2010年 | 305篇 |
2009年 | 361篇 |
2008年 | 379篇 |
2007年 | 360篇 |
2006年 | 329篇 |
2005年 | 270篇 |
2004年 | 202篇 |
2003年 | 205篇 |
2002年 | 132篇 |
2001年 | 104篇 |
2000年 | 124篇 |
1999年 | 91篇 |
1998年 | 58篇 |
1997年 | 77篇 |
1996年 | 57篇 |
1995年 | 54篇 |
1994年 | 66篇 |
1993年 | 54篇 |
1992年 | 54篇 |
1991年 | 38篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 34篇 |
1984年 | 37篇 |
1983年 | 27篇 |
1982年 | 33篇 |
1981年 | 29篇 |
1980年 | 23篇 |
1979年 | 18篇 |
1978年 | 17篇 |
1977年 | 16篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 11篇 |
排序方式: 共有7058条查询结果,搜索用时 15 毫秒
1.
Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon (PAH) in particulate matter that has a diameter of ≤2.5 μm (PM2.5). Studies have demonstrated that BaP exposure causes oocyte meiotic arrest in mice. However, whether BaP exposure also affects oocyte maturation in offspring remains unclear. To test this, female mice were administered BaP before pregnancy to generate BaP-exposed offspring. Our findings showed that BaP exposure reduced the in vitro maturation and increased the abnormalities of meiotic apparatus in offspring oocytes. In addition, BaP exposure reduced the mitochondrial content and intracellular ATP generation, induced early apoptosis, increased reactive oxidative species accumulation and the genomic DNA 5-methylcytosine (5mc) level in offspring oocytes. Along with the abovementioned defective parameters, maternal BaP exposure further compromised the embryo developmental competence of offspring oocytes. In summary, our study demonstrated that maternal BaP exposure compromised offspring oocyte maturation and quality. 相似文献
2.
Puja Vijay Parikh 《International journal of environmental health research》2016,26(4):458-466
Environmental chemical exposure could be an important etiologic factor for geographic differences in breast cancer incidence. In this study, we examined emissions of polycyclic aromatic hydrocarbons (PAHs) and PM2.5 in relation to breast cancer incidence in metro Atlanta and rural Georgia by analyzing data from the Surveillance, Epidemiology, and End Results Program and the Environmental Protection Agency. The results showed that metro Atlanta had a significantly higher age-adjusted annual incidence rate of female breast cancer than rural Georgia (132.6 vs. 113.7 per 100,000) for 1992–2011. Emissions of both PAHs [adjusted β = 0.568 (95 % CI: 0.209, 0.927); p = 0.004] and PM2.5 [adjusted β = 2.964 (95 % CI: 0.468, 5.459); p = 0.023] were significantly associated with breast cancer incidence in metro Atlanta area. This study suggests that ambient air pollution, especially PAHs and PM2.5, could have a significant impact on the increased incidence of female breast cancer in urban areas. 相似文献
3.
目的建立环境水样中痕量铜的浊点萃取(cloud point extraction,CPE)-火焰原子吸收光谱(flame atomic absorption spectrometry,FAAS)测定法。方法样品在p H 9.5的条件下,加入0.4 ml的1 mmol/L 2-(5-溴-2-吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)溶液,0.1%氯化钙溶液0.1 ml,5%(W/V)Triton X-114溶液0.8 ml,40℃加热15 min后离心,采用火焰原子吸收光谱法进行检测。结果在2~240μg/L的线性范围内,所得回归方程为A=0.002 7c+0.024 6,r=0.995 8。以3倍信噪比计算,方法的检出限为0.62μg/L,富集倍数为36.58倍,平均加标回收率为96.28%~98.08%,RSD为1.67%~3.13%。结论该方法简单、灵敏,具有良好的重现性,适用于环境水样中痕量铜的测定。 相似文献
4.
Chien-Hua Tseng Ben-Jei Tsuang Chun-Ju Chiang Kai-Chen Ku Jeng-Sen Tseng Tsung-Ying Yang Kuo-Hsuan Hsu Kun-Chieh Chen Sung-Liang Yu Wen-Chung Lee Tsang-Wu Liu Chang-Chuan Chan Gee-Chen Chang 《Journal of thoracic oncology》2019,14(5):784-792
Introduction
For never-smokers (smoked <100 lifetime cigarettes), lung cancer (LC) has emerged as an important issue. We aimed to investigate the effects of prevalence changes in tobacco smoking and particulate matter (PM) 2.5 (PM2.5) levels on LC in Taiwan, in relation to contrasting PM2.5 levels, between Northern Taiwan (NT) and Southern Taiwan (ST).Methods
We reviewed 371,084 patients with LC to assess smoking prevalence and correlations between the incidence of adenocarcinoma lung cancer (AdLC) and non-AdLC. Two subsets were selected to assess different AdLC stage trends and the effect of PM2.5 on survival of patients with AdLC.Results
From 1995 to 2015, the proportion of male adult ever-smokers decreased from 59.4% to 29.9% whereas the female smoking rate remained low (3.2% to 5.3%). AdLC incidence in males and females increased from 9.06 to 23.25 and 7.05 to 24.22 per 100,000 population, respectively. Since 1993, atmospheric visibility in NT improved (from 7.6 to 11.5 km), but deteriorated in ST (from 16.3 to 4.2 km). The annual percent change in AdLC stages IB to IV was 0.3% since 2009 (95% confidence interval [CI]: -1.9%–2.6%) in NT, and 4.6% since 2007 (95% CI: 3.3%–5.8%) in ST; 53% patients with LC had never smoked. Five-year survival rates for never-smokers, those with EGFR wild-type genes, and female patients with AdLC were 12.6% in NT and 4.5% in ST (hazard ratio: 0.79, 95% CI: 0.70–0.90).Conclusions
In Taiwan, greater than 50% of patients with LC had never smoked. PM2.5 level changes can affect AdLC incidence and patient survival. 相似文献5.
Seulkee Heo 《International journal of environmental health research》2015,25(3):330-348
In this study, we estimated the disease burdens attributable to environmental tobacco smoke (ETS) exposure in Korean adults in 2010 and analyzed the trend of that from 2005 to 2010. We obtained information on the study population from the 2010 Cause of Death Statistic and estimated the ETS-attributable fraction using data from the Korean Community Health Survey and the Korean National Health and Nutrition Examination Survey. The numbers of ETS-attributable deaths in female and male non-smokers were estimated to be 4.1 and 69.6?% of the numbers of deaths attributable to current smoke, respectively. The deaths attributable to ETS were larger in female than in male non-smokers (710 vs. 420). The ETS-attributable deaths increased slightly in 2005–2008 but decreased in 2009–2010. The number of potential years of life lost from ETS was 9077.24?years in 2010. If there were no exposure to ETS in adult non-smokers, we would expect to see 1130 fewer deaths (9.9?% of the deaths from current smoke). The results suggest that ETS poses considerable disease burdens for non-smokers, especially women, in Korea. 相似文献
6.
《Health & place》2020
In this study we used a participatory research method, photovoice, to explore community perceptions about environmental health risks, community assets, and strengths in and around an urban, degraded watershed in Northwest Atlanta, Georgia. This watershed, formed by Proctor Creek, is a focal point for redevelopment and infrastructure investments for years to come. Using a community-based participatory research approach, 10 Proctor Creek residents (watershed researchers), and a university partner, engaged in data collection; participatory data analysis; internal discussions; translation of research findings into watershed restoration, community revitalization, remedial action, and policy solutions; and dissemination of results to fellow watershed residents, stakeholders, and decision makers. We present a conceptual model linking the watershed researchers' understanding of urban policies and practice in the Proctor Creek Watershed to environmental, neighborhood and housing conditions and their influence on health outcomes and quality of life. Engaging community members in defining their own community environmental health challenges and assets yielded the following primary themes: 1) threats to the natural environment, 2) built environment stressors that influence health, 3) blight and divestment of public resources, and 4) hope for the future. Residents’ vision for the future of the watershed - a restored creek, revitalized neighborhoods, and restored people - is fueled by a strong connection to history, memory, and sense of place. We demonstrate the value of local knowledge in identifying previously unaddressed environmental health risks in the Proctor Creek Watershed as well as solutions to reduce or eliminate them. 相似文献
7.
《Vaccine》2016,34(50):6316-6322
ObjectiveAir pollution, weather condition and influenza are known risk factors of acute coronary syndrome (ACS) among elderly people. The influenza vaccine (IV) has been shown to reduce major cardiovascular events. The purpose of this study was to compare resistance to air pollution and weather factors causing ACS between vaccinated and less-vaccinated elderly people.MethodsA case–crossover design was applied to 1835 elderly ACS patients who were obtained from the 1-million sample of Taiwan National Health Insurance Research Data with inclusion criteria: (1) the first diagnosis of ACS was in cold season and at age 68 or more, (2) had received the free IV program at least once during the period 3 years before the ACS. They were stratified into two groups: 707 had received flu vaccinations for all the 3 years and the remaining 1128 had not. The measurements of air pollutants, temperature, and humidity corresponding to each of the 3 days prior to the ACS diagnosis date were retrieved from the data banks of the Taiwan Environmental Protection Administration and Central Weather Bureau.FindingsIncreases in air pollution concentrations of CO, NO2, PM10 or PM2.5 and decreases in temperature significantly influenced the risk of ACS for the non-continuously vaccinated elderly population; however, less significant effects were observed for the continuously vaccinated population.ConclusionConsecutive influenza vaccination may potentially offer resistance against the detrimental effects of air pollution and changes in temperature in frail elderly adults with ACS. Future studies are needed to directly assess the interaction effect between the vaccination and environmental factors on ACS. 相似文献
8.
9.
本文用气相色谱法对居住福州、长乐、宁化三个地区270名健康人群发铬含量进行调查。结果表明:福州地区发铬值高于其它两地区,并有非常显著性差异。总体发铬算术平均数与国内外部分地区所报导的结果比较接近,但在性别及年龄间差异不明显。对三个地区发铬值与当地土壤铬含量进行相关分析,r=0.9978,二者呈正相关,并有非常显著性意义。 相似文献
10.
松花江汞污染治理后沿江渔民发汞调查 总被引:1,自引:0,他引:1
调查结果表明,沿江渔民发汞均值为2.25μg/g,与对照点相比差异显著(P<0.01),其中扶余一松江段渔民发汞均值2.54μg/g,高于其他各江段;30~40岁年龄组渔民发汞值超过正常值者占45%,比其他各年龄组多;在调查的1195人中有25名发汞值超过10μg/g,其中18人发甲基汞含量超过5μg/g。 相似文献