收费全文 | 11925篇 |
免费 | 109篇 |
国内免费 | 89篇 |
安全科学 | 337篇 |
废物处理 | 443篇 |
环保管理 | 1642篇 |
综合类 | 2118篇 |
基础理论 | 3139篇 |
环境理论 | 7篇 |
污染及防治 | 2982篇 |
评价与监测 | 742篇 |
社会与环境 | 628篇 |
灾害及防治 | 85篇 |
2023年 | 67篇 |
2022年 | 110篇 |
2021年 | 100篇 |
2020年 | 80篇 |
2019年 | 95篇 |
2018年 | 163篇 |
2017年 | 144篇 |
2016年 | 223篇 |
2015年 | 194篇 |
2014年 | 269篇 |
2013年 | 885篇 |
2012年 | 357篇 |
2011年 | 498篇 |
2010年 | 410篇 |
2009年 | 481篇 |
2008年 | 522篇 |
2007年 | 520篇 |
2006年 | 456篇 |
2005年 | 422篇 |
2004年 | 353篇 |
2003年 | 366篇 |
2002年 | 353篇 |
2001年 | 472篇 |
2000年 | 346篇 |
1999年 | 209篇 |
1998年 | 131篇 |
1997年 | 157篇 |
1996年 | 163篇 |
1995年 | 190篇 |
1994年 | 192篇 |
1993年 | 159篇 |
1992年 | 132篇 |
1991年 | 169篇 |
1990年 | 164篇 |
1989年 | 157篇 |
1988年 | 115篇 |
1987年 | 114篇 |
1986年 | 118篇 |
1985年 | 91篇 |
1984年 | 108篇 |
1983年 | 110篇 |
1982年 | 118篇 |
1981年 | 108篇 |
1980年 | 96篇 |
1979年 | 112篇 |
1978年 | 73篇 |
1977年 | 76篇 |
1975年 | 76篇 |
1973年 | 72篇 |
1967年 | 66篇 |
Methods: The analysis was conducted using a 50th percentile male occupant human body model with deployed KABs in a simplified vehicle interior. The 2 common KAB design types, bottom-deploy KAB (BKAB) and rear-deploy KAB (RKAB), were both included. A state-of-the-art airbag modeling technique, the corpuscular particle method, was adopted to represent the deployment dynamics of the unfolding airbags. Validation of the environment model was performed based on previously reported test results. The kinematic responses of the occupant lower extremities were compared under both KAB designs, 2 seating configurations (in-position and out-of-position), and 3 loading conditions (static, frontal, and oblique impacts). A linear statistical model was used to assess factor significance considering the impact responses of the occupant lower extremities.
Results: The presence of a KAB had a significant influence on the lower extremity kinematics compared to no KAB (P <.05) by providing early restraint and distributing contact force on the legs during airbag deployment. For in-position occupants, the KAB generally tended to decrease tibia loadings. The RKAB led to greater lateral motion of the legs compared to the BKAB, resulting in higher lateral displacement at the knee joint and abduction angle change (51.2 ± 21.7 mm and 15° ± 6.0°) over the dynamic loading conditions. Change in the seating position led to a significant difference in occupant kinematic and kinetic parameters (P <.05). For the out-of-position (forward-seated) occupant, the earlier contact between the lower extremity and the deploying KAB resulted in 28.4° ± 5.8° greater abduction, regardless of crash scenarios. Both KAB types reduced the axial force in the femur relative to no KAB. Overall, the out-of-position occupant sustained a raised axial force and bending moment of the tibia by 0.8 ± 0.2 kN and 21.1 ± 8.7 Nm regardless of restraint use.
Conclusions: The current study provided a preliminary computational examination on KAB designs based on a limited set of configurations in an idealized vehicle interior. Results suggested that the BKAB tended to provide more coverage and less leg abduction compared to the RKAB in oblique impact and/or the selected out-of-position scenario. An out-of-position occupant was associated with larger abduction and lower extremity loads over all occupant configurations. Further investigations are recommended to obtain a full understanding of the KAB performance in a more realistic vehicle environment. 相似文献
Methods: The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant (M50-O) and the Humanetics Hybrid III 50th percentile models were gravity settled in the driver position of a generic interior equipped with an advanced 3-point belt and driver airbag. Fifteen simulations per model (30 total) were conducted, including 4 scenarios at 3 severity levels: median, severe, and the U.S. New Car Assessment Program (U.S.-NCAP) and 3 extra per model with high-intensity braking. The 4 scenarios were no precollision system (no PCS), forward collision warning (FCW), FCW with prebraking assist (FCW+PBA), and FCW and PBA with autonomous precrash braking (FCW + PBA + PB). The baseline ΔV was 17, 34, and 56.4 kph for median, severe, and U.S.-NCAP scenarios, respectively, and were based on crash reconstructions from NASS/CDS. Pulses were then developed based on the assumed precrash systems equipped. Restraint properties and the generic pulse used were based on literature.
Results: In median crash severity cases, little to no risk (<10% risk for Abbreviated injury Scale [AIS] 3+) was found for all injury measures for both models. In the severe set of cases, little to no risk for AIS 3+ injury was also found for all injury measures. In NCAP cases, highest risk was typically found with No PCS and lowest with FCW + PBA + PB. In the higher intensity braking cases (1.0–1.4 g), head injury criterion (HIC), brain injury criterion (BrIC), and chest deflection injury measures increased with increased braking intensity. All other measures for these cases tended to decrease. The ATD also predicted and trended similar to the human body models predictions for both the median, severe, and NCAP cases. Forward excursion for both models decreased across median, severe, and NCAP cases and diverged from each other in cases above 1.0 g of braking intensity.
Conclusions: The addition of precrash systems simulated through reduced precrash speeds caused reductions in some injury criteria, whereas others (chest deflection, HIC, and BrIC) increased due to a modified occupant position. The human model and ATD models trended similarly in nearly all cases with greater risk indicated in the human model. These results suggest the need for integrated safety systems that have restraints that optimize the occupant's position during precrash braking and prior to impact. 相似文献