收费全文 | 6265篇 |
免费 | 521篇 |
国内免费 | 116篇 |
安全科学 | 5173篇 |
废物处理 | 27篇 |
环保管理 | 256篇 |
综合类 | 991篇 |
基础理论 | 155篇 |
环境理论 | 1篇 |
污染及防治 | 51篇 |
评价与监测 | 34篇 |
社会与环境 | 84篇 |
灾害及防治 | 130篇 |
2024年 | 2篇 |
2023年 | 49篇 |
2022年 | 143篇 |
2021年 | 241篇 |
2020年 | 269篇 |
2019年 | 280篇 |
2018年 | 105篇 |
2017年 | 365篇 |
2016年 | 251篇 |
2015年 | 432篇 |
2014年 | 183篇 |
2013年 | 249篇 |
2012年 | 443篇 |
2011年 | 484篇 |
2010年 | 376篇 |
2009年 | 406篇 |
2008年 | 236篇 |
2007年 | 450篇 |
2006年 | 478篇 |
2005年 | 354篇 |
2004年 | 242篇 |
2003年 | 248篇 |
2002年 | 179篇 |
2001年 | 115篇 |
2000年 | 86篇 |
1999年 | 39篇 |
1998年 | 47篇 |
1997年 | 22篇 |
1996年 | 29篇 |
1995年 | 35篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
Method: A questionnaire survey is conducted to understand the awareness of EMS and their function. Using traffic-related fatalities as the dependent variable, a fixed effect panel data model is developed to analyze the effectiveness of the 108 services in improving the traffic safety.
Results: The results from the survey show that, in general, people are not aware of the 108 services. A majority of the population prefers taking victims to the hospital using their personal vehicles or any other vehicles available compared to calling an ambulance. Results from panel data analysis show that despite having an efficient system, these services failed to make significant improvement in the safety of road users in the states in which their services were subscribed.
Discussion: The lack of awareness of an important safety service is alarming. This could be a major reason for lower utilization of 108 services for transporting victims of traffic crashes. This article shows the importance of having efficient awareness campaigns to improve the efficiency of any similar programs that are aimed to enhance the safety of a region. 相似文献
Methods: One hundred thirty-eight children from the second (7–8 years), fourth (9–10 years), and sixth (11–12 years) grades performed a practical bicycle test consisting of 13 test items with specific points of interest. Moreover, age at onset of cycling, cycling to and from school, independent mobility, and minutes cycling per week were estimated using a parental questionnaire.
Results: It is found that cycling skills are strongly related to age with 11- to 12-year-old children outperforming 7- to 8-year-old children for 11 test items and 9- to 10-year-old children for 8 test items.
Conclusions: Next to age, age at onset of cycling also contributed to cycling skills. Therefore, our results suggest that cycling skills are associated with physical and mental maturation. Subsequently, age-related reference values are provided to customize testing and training. 相似文献