收费全文 | 10914篇 |
免费 | 975篇 |
国内免费 | 2126篇 |
安全科学 | 2700篇 |
废物处理 | 127篇 |
环保管理 | 1529篇 |
综合类 | 5577篇 |
基础理论 | 1365篇 |
环境理论 | 3篇 |
污染及防治 | 592篇 |
评价与监测 | 766篇 |
社会与环境 | 525篇 |
灾害及防治 | 831篇 |
2024年 | 61篇 |
2023年 | 272篇 |
2022年 | 381篇 |
2021年 | 497篇 |
2020年 | 490篇 |
2019年 | 477篇 |
2018年 | 382篇 |
2017年 | 475篇 |
2016年 | 579篇 |
2015年 | 597篇 |
2014年 | 619篇 |
2013年 | 871篇 |
2012年 | 876篇 |
2011年 | 1007篇 |
2010年 | 655篇 |
2009年 | 754篇 |
2008年 | 538篇 |
2007年 | 706篇 |
2006年 | 662篇 |
2005年 | 481篇 |
2004年 | 374篇 |
2003年 | 373篇 |
2002年 | 297篇 |
2001年 | 247篇 |
2000年 | 249篇 |
1999年 | 197篇 |
1998年 | 139篇 |
1997年 | 142篇 |
1996年 | 95篇 |
1995年 | 115篇 |
1994年 | 71篇 |
1993年 | 69篇 |
1992年 | 48篇 |
1991年 | 43篇 |
1990年 | 23篇 |
1989年 | 16篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 12篇 |
1981年 | 19篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1973年 | 2篇 |
1969年 | 1篇 |
Methods: The Spanish version of the Behaviour of Young Novice Drivers Scale (BYNDS-Sp) was applied in an online survey to a sample of 392 students (225 males) aged 16–24 years attending a major university. Appropriate comparative statistics and logistic regression modeling were used when analyzing the data.
Results: Males reported consistently more risky driving behaviors, with approximately one quarter of all participants reporting risky driving exposure. Males reported greater crash involvement, with violations such as speeding associated with crash involvement for both males and females.
Conclusion: Young drivers in Colombia appear to engage in the same risky driving behaviors as young drivers in developed nations. In addition, young male drivers in Colombia reported greater engagement in risky driving behaviors than young female drivers, a finding consistent with the behaviors of young male drivers in developed nations. As such, the research findings suggest that general interventions such as education, engineering, and enforcement should target transient rule violations such as speeding and using a handheld mobile phone while driving for young drivers in Colombia. Future research should investigate how these interventions could be tailored specifically for the Colombian cultural context, including how their effects can be evaluated, prior to implementation. 相似文献
Methods: This study seeks to develop a generalized evaluation scheme that can be used not only to assess the effectiveness of IMA on improving traffic safety at intersections but to facilitate comparisons across similar studies. The proposed evaluation scheme utilizes the concepts of traffic conflict in terms of time-to-collision (TTC) as a crash surrogate. This approach avoids the issue of having insufficient crash frequency data for system evaluation. To measure the effectiveness of IMA on reducing traffic conflicts, a relative risk is calculated for comparing the risk of with/without using the IMA. As a proof-of-concept study, this study applied the proposed evaluation scheme and reported the effectiveness of IMA on improving traffic safety in a field operation test (FOT). Seven test scenarios were conducted at 4 intersections, and a total of 40 participants were recruited to use the IMA for 6 months.
Results: It was estimated that IMA users have 26% fewer conflicts with TTC less than 5 s and have 15% fewer conflicts with TTC less than 4 s. However, the results vary across different sites and different definitions of conflicts in terms of TTC.
Conclusions: Overall, IMA is promising to effectively reduce angle crashes related to sight obstruction and has potential to reduce not only crash frequency but crash severity. 相似文献