全文获取类型
收费全文 | 773篇 |
免费 | 83篇 |
出版年
2021年 | 10篇 |
2020年 | 5篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 16篇 |
2015年 | 19篇 |
2014年 | 17篇 |
2013年 | 36篇 |
2012年 | 43篇 |
2011年 | 51篇 |
2010年 | 20篇 |
2009年 | 20篇 |
2008年 | 42篇 |
2007年 | 34篇 |
2006年 | 33篇 |
2005年 | 32篇 |
2004年 | 25篇 |
2003年 | 25篇 |
2002年 | 30篇 |
2001年 | 19篇 |
2000年 | 22篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1995年 | 14篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1983年 | 10篇 |
1982年 | 8篇 |
1979年 | 5篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 5篇 |
1972年 | 9篇 |
1971年 | 6篇 |
1970年 | 7篇 |
1969年 | 6篇 |
1968年 | 5篇 |
1966年 | 6篇 |
1965年 | 5篇 |
1945年 | 5篇 |
排序方式: 共有856条查询结果,搜索用时 203 毫秒
791.
792.
William Lee Stokes 《Palaeogeography, Palaeoclimatology, Palaeoecology》1978,25(4):353-364
Fossils of the lacustrine Green River Formation (Early Eocene) of Colorado, Utah, and Wyoming consist of few indigenous and many transported elements, among those that were obviously produced in environments different from those of final burial are adult and larval insects, gymnosperm and angiosperm leaves, feathers, and patches of moulted lizard skin. Of these the insect larvae are most abundant and difficult to explain. The relatively undamaged condition of delicate organisms seems to rule out extensive water transport. It is concluded that strong winds acting either to carry specimens through the air or to drive them over the water surface delivered many of these organic objects to the place of burial and fossilization. 相似文献
793.
794.
Semira Manaseki-Holland Buba Manjang Karla Hemming James T. Martin Christopher Bradley Louise Jackson Makie Taal Om Prasad Gautam Francesca Crowe Bakary Sanneh Jeroen Ensink Tim Stokes Sandy Cairncross 《PLoS medicine》2021,18(1)
BackgroundThe Gambia has high rates of under-5 mortality from diarrhoea and pneumonia, peaking during complementary-feeding age. Community-based interventions may reduce complementary-food contamination and disease rates.Methods and findingsA public health intervention using critical control points and motivational drivers, delivered February–April 2015 in The Gambia, was evaluated in a cluster randomised controlled trial at 6- and 32-month follow-up in September–October 2015 and October–December 2017, respectively. After consent for trial participation and baseline data were collected, 30 villages (clusters) were randomly assigned to intervention or control, stratified by population size and geography. The intervention included a community-wide campaign on days 1, 2, 17, and 25, a reminder visit at 5 months, plus informal community-volunteer home visits. It promoted 5 key complementary-food and 1 key drinking-water safety and hygiene behaviours through performing arts, public meetings, and certifications delivered by a team from local health and village structures to all villagers who attended the activities, to which mothers of 6- to 24-month-old children were specifically invited. Control villages received a 1-day campaign on domestic-garden water use. The background characteristics of mother and clusters (villages) were balanced between the trial arms. Outcomes were measured at 6 and 32 months in a random sample of 21–26 mothers per cluster. There were no intervention or research team visits to villages between 6 and 32 months. The primary outcome was a composite outcome of the number of times key complementary-food behaviours were observed as a proportion of the number of opportunities to perform the behaviours during the observation period at 6 months. Secondary outcomes included the rate of each recommended behaviour; microbiological growth from complementary food and drinking water (6 months only); and reported acute respiratory infections, diarrhoea, and diarrhoea hospitalisation. Analysis was by intention-to-treat analysis adjusted by clustering. (Registration: PACTR201410000859336). We found that 394/571 (69%) of mothers with complementary-feeding children in the intervention villages were actively involved in the campaign. No villages withdrew, and there were no changes in the implementation of the intervention. The intervention improved behaviour adoption significantly. For the primary outcome, the rate was 662/4,351(incidence rate [IR] = 0.15) in control villages versus 2,861/4,378 (IR = 0.65) in intervention villages (adjusted incidence rate ratio [aIRR] = 4.44, 95% CI 3.62–5.44, p < 0.001), and at 32 months the aIRR was 1.17 (95% CI 1.07–1.29, p = 0.001). Secondary health outcomes also improved with the intervention: (1) mother-reported diarrhoea at 6 months, with adjusted relative risk (aRR) = 0.39 (95% CI 0.32–0.48, p < 0.001), and at 32 months, with aRR = 0.68 (95% CI 0.48–0.96, p = 0.027); (2) mother-reported diarrhoea hospitalisation at 6 months, with aRR = 0.35 (95% CI 0.19–0.66, p = 0.001), and at 32 months, with aRR = 0.38 (95% CI 0.18–0.80, p = 0.011); and (3) mother-reported acute respiratory tract infections at 6 months, with aRR = 0.67 (95% CI 0.53–0.86, p = 0.001), though at 32 months improvement was not significant (p = 0.200). No adverse events were reported. The main limitations were that only medium to small rural villages were involved. Obtaining laboratory cultures from food at 32 months was not possible, and no stool microorganisms were investigated.ConclusionsWe found that low-cost and culturally embedded behaviour change interventions were acceptable to communities and led to short- and long-term improvements in complementary-food safety and hygiene practices, and reported diarrhoea and acute respiratory tract infections.Trial registrationThe trial was registered on the 17th October 2014 with the Pan African Clinical Trial Registry in South Africa with number (PACTR201410000859336) and 32-month follow-up as an amendment to the trial.Semira Manaseki-Holland and co-workers evaluate a behaviour-change intervention aimed at improving food hygiene for infants in West Africa. 相似文献
795.
796.
797.
798.
799.
800.