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   379篇
  免费   22篇
  国内免费   5篇
安全科学   37篇
废物处理   10篇
环保管理   97篇
综合类   44篇
基础理论   117篇
环境理论   2篇
污染及防治   52篇
评价与监测   26篇
社会与环境   16篇
灾害及防治   5篇
  2023年   9篇
  2022年   5篇
  2021年   8篇
  2020年   14篇
  2019年   11篇
  2018年   21篇
  2017年   15篇
  2016年   25篇
  2015年   19篇
  2014年   17篇
  2013年   28篇
  2012年   35篇
  2011年   26篇
  2010年   14篇
  2009年   27篇
  2008年   22篇
  2007年   20篇
  2006年   21篇
  2005年   13篇
  2004年   7篇
  2003年   10篇
  2002年   8篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   1篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1986年   1篇
  1985年   1篇
  1982年   1篇
  1981年   5篇
  1980年   4篇
  1977年   2篇
排序方式: 共有406条查询结果,搜索用时 609 毫秒
251.
Enterprises are playing increasing roles in facilitating access to sanitation products and services in Indonesia and other developing economies. This study investigated the factors affecting the sustainability of sanitation enterprises in rural Indonesia. Interviews with 33 organisations representing sanitation enterprises, associations of sanitation enterprises, national and international civil society organisations (CSOs), donor organisations and national and local government agencies were conducted to explore different stakeholder perceptions about enterprise roles. The research revealed factors specific to the sanitation entrepreneurs themselves, such as their skills, entrepreneurial traits, pro-social motivations and intrinsic motivations, as well as factors within their enabling environment. Insufficient customer demand, inadequate capacity building opportunities, lack of financing options for entrepreneurs and their customers, and limited government support were observed to undermine sanitation enterprise success. Industry associations were found to be a useful intermediary support mechanism, particularly in the absence of significant government support for enterprises. However, such associations could also stifle innovation, and their role needs to be carefully developed, including financially sustainable models for such associations. This study has implications for how governments and CSOs in Indonesia and elsewhere might best support the role of enterprises and entrepreneurship towards improved sanitation outcomes.  相似文献   
252.
This article describes the collaborative modeling process and the resulting water resources planning model developed to evaluate water management scenarios in the transboundary Rio Grande basin. The Rio Grande is a severely water stressed basin that faces numerous management challenges as it crosses numerous jurisdictional boundaries. A collaborative process was undertaken to identify and model water management scenarios to improve water supply for stakeholders, the environment, and international obligations of water delivery from Mexico to the United States. A transparent and open process of data collection, model building, and scenario development was completed by a project steering committee composed of university, nongovernmental, and governmental experts from both countries. The outcome of the process was a planning model described in this article, with data and operations that were agreed on by water planning officials in each country. Water management scenarios were created from stakeholder input and were modeled and evaluated for effectiveness with the planning model.  相似文献   
253.
Ecological systems often operate on time scales significantly longer or shorter than the time scales typical of human decision making, which causes substantial difficulty for conservation and management in socioecological systems. For example, invasive species may move faster than humans can diagnose problems and initiate solutions, and climate systems may exhibit long‐term inertia and short‐term fluctuations that obscure learning about the efficacy of management efforts in many ecological systems. We adopted a management‐decision framework that distinguishes decision makers within public institutions from individual actors within the social system, calls attention to the ways socioecological systems respond to decision makers’ actions, and notes institutional learning that accrues from observing these responses. We used this framework, along with insights from bedeviling conservation problems, to create a typology that identifies problematic time‐scale mismatches occurring between individual decision makers in public institutions and between individual actors in the social or ecological system. We also considered solutions that involve modifying human perception and behavior at the individual level as a means of resolving these problematic mismatches. The potential solutions are derived from the behavioral economics and psychology literature on temporal challenges in decision making, such as the human tendency to discount future outcomes at irrationally high rates. These solutions range from framing environmental decisions to enhance the salience of long‐term consequences, to using structured decision processes that make time scales of actions and consequences more explicit, to structural solutions aimed at altering the consequences of short‐sighted behavior to make it less appealing. Additional application of these tools and long‐term evaluation measures that assess not just behavioral changes but also associated changes in ecological systems are needed.  相似文献   
254.
Environmental Management - Constructed stormwater wetlands (CSWs) are used to address contaminants in urban stormwater such as nitrogen (N) and phosphorus (P), but their performance is variable....  相似文献   
255.
256.
257.

Problem

Although Graduated Driver Licensing Systems (GDLS) have helped reduce young driver crash rates, they remain significantly over-represented in crash statistics. To be effective GDLS rely heavily on support for the legislation by those directly involved; parents to enforce the restrictions and adolescents to comply. There is some evidence that practices regarding GDLS restrictions influence adolescent driving outcomes in the early stage of licensure. However there has been no examination undertaken on the influence of parent and adolescent attitudes toward GDLS on adolescents’ driving behavior and crash experiences as they move into their young adult years. The aim of this research was to examine these relationships.

Method

This investigation was based on a longitudinal study of a birth cohort, and uses data collected when the cohort members were aged 15, 18, and 21 years. At age 15 both adolescent and their parent attitudes toward GDLS were measured. At age 18 adolescent GDLS attitudes were measured again. The association between these measures and self-reported risky driving behavior and crash involvement at age 21 were examined.

Results

Negative attitudes toward the learner supervisor restriction for males, and negative attitudes toward a GDLS for females were strongly associated with risky driving and crash involvement as young adults.

Impact on industry

Targeting interventions to improve adolescents and parents understanding of the reasons for graduated licensing and the specific restrictions may improve attitudes and views and thereby contribute to a reduction in risky driving behaviors and crash risk among young adults.  相似文献   
258.
259.

Objective

Carrier screening with reflex to single-gene noninvasive prenatal testing (sgNIPT) is an alternative approach for identifying pregnancies at risk for inherited autosomal recessive conditions without the need for a sample from the reproductive partner. This study is the largest clinical validation of this approach in a general population setting.

Methods

The clinical performance of carrier screening with reflex to sgNIPT for cystic fibrosis, spinal muscular atrophy, alpha thalassemias, and beta hemoglobinopathies was assessed by collecting pregnancy outcome data on patients who underwent this testing and comparing the neonatal outcome to the assay-predicted fetal risk.

Results

Of 42,067 pregnant individuals who underwent screening, 7538 carriers (17.9%) had reflex sgNIPT, and neonatal or fetal outcomes were obtained for 528 cases, including 25 affected pregnancies. Outcomes demonstrated high concordance with sgNIPT, for example, all pregnancies with 9 in 10 personalized fetal risk results were affected (positive predictive value (PPV) of 100% for the sub-group) and the sgNIPT assay showed a sensitivity of 96.0% (95% CI: 79.65%–99.90%), specificity of 95.2% (95% CI: 92.98%–96.92%), average PPV of 50.0% (95% CI: 35.23%–64.77%), and negative predictive value (NPV) of 99.8% (95% CI: 98.84%–99.99%). The end-to-end performance of carrier screening with reflex to sgNIPT was calculated to have a sensitivity of 92.4% and specificity of 99.9%, which are unaffected by partner carrier screening or misattributed paternity unlike a traditional carrier screening workflow, which has a 35% sensitivity and a maximum of 25% PPV (1 in 4) in a real-life setting.

Conclusion

This study builds upon earlier findings to confirm that carrier testing with reflex to sgNIPT is highly accurate for general population screening. Given this high accuracy and an NPV of 99.8%, this workflow should be considered as an option for most of the general pregnant population. When the biological partner sample is unavailable, this workflow should be recommended as the first-line approach.  相似文献   
260.

Objective

To develop a multi-step workflow for the isolation of circulating extravillous trophoblasts (cEVTs) by describing the key steps enabling a semi-automated process, including a proprietary algorithm for fetal cell origin genetic confirmation and copy number variant (CNV) detection.

Methods

Determination of the limit of detection (LoD) for submicroscopic CNV was performed by serial experiments with genomic DNA and single cells from Coriell cell line biobank with known imbalances of different sizes. A pregnancy population of 372 women was prospectively enrolled and blindly analyzed to evaluate the current workflow.

Results

An LoD of 800 Kb was demonstrated with Coriell cell lines. This level of resolution was confirmed in the clinical cohort with the identification of a pathogenic CNV of 800 Kb, also detected by chromosomal microarray. The mean number of recovered cEVTs was 3.5 cells per sample with a significant reverse linear trend between gestational age and cEVT recovery rate and number of recovered cEVTs. In twin pregnanices, evaluation of zygosity, fetal sex and copy number profiling was performed in each individual cell.

Conclusion

Our semi-automated methodology for the isolation and single-cell analysis of cEVTS supports the feasibility of a cell-based noninvasive prenatal test for fetal genomic profiling.  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