全文获取类型
收费全文 | 25641篇 |
免费 | 329篇 |
国内免费 | 409篇 |
专业分类
安全科学 | 767篇 |
废物处理 | 1107篇 |
环保管理 | 3079篇 |
综合类 | 5268篇 |
基础理论 | 6304篇 |
环境理论 | 12篇 |
污染及防治 | 6459篇 |
评价与监测 | 1517篇 |
社会与环境 | 1701篇 |
灾害及防治 | 165篇 |
出版年
2023年 | 157篇 |
2022年 | 279篇 |
2021年 | 250篇 |
2020年 | 234篇 |
2019年 | 213篇 |
2018年 | 406篇 |
2017年 | 391篇 |
2016年 | 565篇 |
2015年 | 457篇 |
2014年 | 644篇 |
2013年 | 1921篇 |
2012年 | 851篇 |
2011年 | 1152篇 |
2010年 | 936篇 |
2009年 | 1039篇 |
2008年 | 1155篇 |
2007年 | 1205篇 |
2006年 | 1018篇 |
2005年 | 857篇 |
2004年 | 861篇 |
2003年 | 848篇 |
2002年 | 737篇 |
2001年 | 915篇 |
2000年 | 712篇 |
1999年 | 468篇 |
1998年 | 296篇 |
1997年 | 321篇 |
1996年 | 293篇 |
1995年 | 363篇 |
1994年 | 316篇 |
1993年 | 285篇 |
1992年 | 249篇 |
1991年 | 261篇 |
1990年 | 266篇 |
1989年 | 247篇 |
1988年 | 225篇 |
1987年 | 195篇 |
1986年 | 218篇 |
1985年 | 206篇 |
1984年 | 243篇 |
1983年 | 201篇 |
1982年 | 232篇 |
1981年 | 191篇 |
1980年 | 178篇 |
1979年 | 203篇 |
1978年 | 145篇 |
1977年 | 147篇 |
1974年 | 135篇 |
1973年 | 137篇 |
1972年 | 136篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
601.
602.
603.
The importance of the incorporation of personal communication devices in emergency evacuation simulators will be discussed. Four case studies are examined to identify usage statistics and human behavior when using the devices in an emergency. The case studies are: 9/11 World Trade Center Attacks, London train bombings, Virginia Tech shooting and United Flight #93. The case studies’ findings are implemented into the Vacate evacuation simulator, which uses particle swarm optimization to mimic human pedestrian behavior. The physical actions of using a device, as well as the reaction to the information transmitted during usage, are examined. Findings show that the effects of the personal communication devices can affect individuals that are close to the user of the device, as well as those not in the local vicinity of the user. These effects, combined with the rapid mainstream acceptance of communication technologies, justify the implementation of personal communication devices into evacuation simulators. 相似文献
604.
某城市污水处理厂二沉池出水拟采用强化混凝技术进行深度处理后用作邻近发电厂的冷却用水。为了指导生产运行,采用正交试验对强化混凝技术的主要影响因素进行了研究。结果表明:影响因素的主次顺序为助凝剂投加量>搅拌转速>接触污泥浓度>絮凝阶段的pH。强化混凝技术处理该二沉池出水的最佳运行工况:PAM浓度为0.3 mg/L,接触污泥浓度为2.5 g/L,搅拌转速为80 r/min,pH为6.0。在最佳运行工况下,浊度由10.0 NTU降至0.5 NTU以下,TP浓度由1.5 mg/L左右降至1.0 mg/L以下,最低可达0.2 mg/L,优于GB/T 19923—2005《城市污水再生利用 工业用水水质》的相关要求。 相似文献
605.
The general integument of reptiles is traditionally defined as being dry, but we report here the discovery of unicellular mucoid glands (UCMG) in the dorsal skin of lizards of the genus Phelsuma (Gekkonidae). To this end, the skin of these lizards and of some others for comparison was studied by scanning electron microscopy and transmission electron microscopy. These photographs showed that the development and function of the UCMGs are related to the skin's sloughing cycle. The UCMGs differentiate at scattered locations from Oberh?utchen cells of the inner (new) epidermal generation, above the differentiating beta-keratin layer. While the inner generation matures, the UCMG increases in size; unlike the surrounding Oberh?utchen cells, it does not develop the spinules that characterize gecko skin. When, upon sloughing, the inner generation becomes the new outer generation, and the Oberh?utchen forms the skin surface, the UCMGs, several per scale, dot the surface as mucus-inflated "blebs" projecting from the surrounding spinulate Oberh?utchen, each nesting in a shallow pit of the underlying beta-keratin. On the surface, the UCMGs rupture and the mucus appears to dissipate in cords, flowing over the tips of the spinules, and incorporating minute foreign bodies. It is concluded that, due to the low wettability of the spinulate surface (derived from the spacing of the spinules), the cords brush off easily, with the mucus functioning as a cleaning agent. 相似文献
606.
607.
608.
This paper explores the implications of work schedule flexibility for family life. Based on data from the 1977 Quality of Employment Survey, it demonstrates that flexibility of work schedules moderates the effects of nonstandard work schedules on family life. That is, nonstandard work schedules tend to have a less negative association with the quality of family life when accompanied by a high level of schedule flexibility. The paper further demonstrates that this tendency of flexibility to act as a buffer against the negative effects of nonstandard work schedules on family life is more pronounced among working women than working men. 相似文献
609.
Cary L. Cooper 《组织行为杂志》1981,2(2):149-150
610.