全文获取类型
收费全文 | 820篇 |
免费 | 28篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 22篇 |
废物处理 | 43篇 |
环保管理 | 231篇 |
综合类 | 94篇 |
基础理论 | 212篇 |
环境理论 | 1篇 |
污染及防治 | 166篇 |
评价与监测 | 44篇 |
社会与环境 | 25篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 21篇 |
2016年 | 23篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 71篇 |
2012年 | 29篇 |
2011年 | 42篇 |
2010年 | 32篇 |
2009年 | 35篇 |
2008年 | 52篇 |
2007年 | 50篇 |
2006年 | 39篇 |
2005年 | 32篇 |
2004年 | 35篇 |
2003年 | 31篇 |
2002年 | 31篇 |
2001年 | 24篇 |
2000年 | 25篇 |
1999年 | 11篇 |
1998年 | 14篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1971年 | 2篇 |
1966年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有852条查询结果,搜索用时 0 毫秒
851.
Vagisha Pruthi Nimrah Abbasi Varsha Thakur Shiri Shinar Anne O’Connor Rachel Silver Tasha Simpson Tim Van Mieghem 《黑龙江环境通报》2023,43(7):881-888
Objective
Ultrasound assessment of the fetal anatomy and fetal echocardiography are feasible in the first trimester of pregnancy. This study was designed to assess the performance of a comprehensive fetal anatomy assessment in a high-risk population at a tertiary fetal medicine unit.Methods
A retrospective review of high-risk patients undergoing comprehensive fetal anatomy ultrasound assessment between 11 weeks and 13 + 6 weeks of gestation was conducted. Findings of the early anatomy ultrasound scan were compared with those of the second trimester anatomy scan, and birth outcomes or post-mortem results.Results
Early anatomy ultrasounds were performed in 765 patients. The sensitivity of the scan for detecting fetal anomalies compared to the birth outcome was 80.5% (95% CI 73.5–86.3) and specificity was 93.1% (95%CI 90.6–95.2). Positive and negative predictive values were 78.5% (95% CI 71.4–84.6) and 93.9% (95% CI 91.4–95.8), respectively. The most missed and overdiagnosed abnormalities were ventricular septal defects. The second trimester ultrasound had sensitivity of 69.0% (95% CI 55.5–80.5) and specificity of 87.5% (95% CI 84.3–90.2).Conclusions
In a high-risk population, early assessments had similar performance metrics as the second trimester anatomy ultrasound. We advocate for a comprehensive fetal assessment in the care of high-risk pregnancies. 相似文献852.
Aleah Bowie Wen Zhou Jingzhi Tan Philip White Tara Stoinski Yanjie Su Brian Hare 《Conservation biology》2022,36(4):e13922
Forests are essential common-pool resources. Understanding children's and adolescents’ motivations for conservation is critical to improving conservation education. In 2 experiments, we investigated 1086 school-aged children and adolescents (6–16 years old) from the United States, China, and the Democratic Republic of Congo. Testing participants in groups, we assessed their motivation for conservation based on collective-risk common-pool goods games in which they were threatened with losing their endowment unless the group donation exceeded a threshold needed to maintain the forest. Extrinsic motivations, rather than intrinsic, tended to lead to successful cooperation to maintain a forest. Certainty of losing individual payoffs significantly boosted successful cooperative conservation efforts across cultures (success rates were 90.63% and 74.19% in the 2 risk-extrinsic conditions, and 43.75% in the control condition). In U.S. participants, 2 extrinsic incentives, priming discussions of the value of forests and delay of payoffs as punishment, also increased success of cooperative conservation (success rates were 97.22% and 76.92% in the 2 extrinsic-incentive conditions, and 29.19% and 30.77% in the 2 control conditions). Conservation simulations, like those we used, may allow educators to encourage forest protection by leading groups to experience successful cooperation and the extrinsic incentives needed to motivate forest conservation. 相似文献