全文获取类型
收费全文 | 805篇 |
免费 | 78篇 |
国内免费 | 157篇 |
专业分类
安全科学 | 122篇 |
废物处理 | 15篇 |
环保管理 | 141篇 |
综合类 | 406篇 |
基础理论 | 110篇 |
环境理论 | 6篇 |
污染及防治 | 87篇 |
评价与监测 | 78篇 |
社会与环境 | 51篇 |
灾害及防治 | 24篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 14篇 |
2021年 | 23篇 |
2020年 | 24篇 |
2019年 | 33篇 |
2018年 | 26篇 |
2017年 | 31篇 |
2016年 | 33篇 |
2015年 | 33篇 |
2014年 | 39篇 |
2013年 | 72篇 |
2012年 | 60篇 |
2011年 | 77篇 |
2010年 | 46篇 |
2009年 | 60篇 |
2008年 | 44篇 |
2007年 | 51篇 |
2006年 | 45篇 |
2005年 | 41篇 |
2004年 | 26篇 |
2003年 | 30篇 |
2002年 | 32篇 |
2001年 | 31篇 |
2000年 | 16篇 |
1999年 | 27篇 |
1998年 | 22篇 |
1997年 | 11篇 |
1996年 | 13篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1040条查询结果,搜索用时 125 毫秒
971.
972.
目的对某千万吨炼化企业应用的核料住计建设项目进行控制效果评价,贯彻落实国家有关职业病防护的法律、法规、规章和标准,从源头控制或消除职业病危害,保护劳动者健康。方法通过资料调研,现场调查与检测,将获取的资料与法律、法规的规定和标准的要求相比较并对符合程度进行评估。结果该企业应用核料住计的辐射防护措施、辐射监测结果、应急准备与响应、辐射防护管理等均符合相关法律、法规的规定和标准的要求。结论该企业应用核料位计建设项目的放射性危害防护设施(措施)基本可以满足竣工验收要求。 相似文献
973.
974.
975.
976.
977.
电子装备面临的强电磁脉冲环境分析 总被引:3,自引:3,他引:0
随着战场电磁环境日趋复杂,大量使用微电子器件和电发火装置的现代化武器装备愈发脆弱。论述了强电磁脉冲特征及对电子设备的损伤机理,以静电放电电磁脉冲(ESDEMP)、雷电磁脉冲(LEMP)、核电磁脉冲(NEMP)、高功率微波及超宽带(HPM&UWB)等典型强电磁脉冲为例,介绍了其数学模型。数学模型解释了强电磁脉冲的产生及变化规律,是实施电磁防护工程的前提和基础。认为只有把握好强电磁脉冲的数学规律,才能做到有效防护。 相似文献
978.
Gerard W. Wall Richard L. GarciaFrank Wechsung Bruce A. Kimball 《Agriculture, ecosystems & environment》2011,144(1):390-404
Atmospheric CO2 concentration (Ca) is rising, predicted to cause global warming, and alter precipitation patterns. During 1994, spring barley (Hordeum vulgare L. cv. Alexis) was grown in a strip-split-plot experimental design to determine the effects that the main plot Ca treatments [A: Ambient at 370 μmol (CO2) mol−1; E: Enriched with free-air CO2 enrichment (FACE) at ∼550 μmol (CO2) mol−1] had on several gas exchange properties of fully expanded sunlit primary leaves. The interacting strip-split-plot irrigation treatments were Dry or Wet [50% (D) or 100% (W) replacement of potential evapotranspiration] at ample nitrogen (261 kg N ha−1) and phosphorous (29 kg P ha−1) fertility. Elevated Ca facilitated drought avoidance by reducing stomatal conductance (gs) by 34% that conserved water and enabled stomata to remain open for a longer period into a drought. This resulted in a 28% reduction in drought-induced midafternoon depression in net assimilation rate (A). Elevated Ca increased A by 37% under Dry and 23% under Wet. Any reduction in A under Wet conditions occurred because of nonstomatal limitations, whereas under Dry it occurred because of stomatal limitations. Elevated Ca increased the diurnal integral of A (A′) that resulted in an increase in the seasonal-long integral of A′ (A″) for barley leaves by 12% (P = 0.14) under both Dry and Wet - 650, 730, 905 and 1020 ± 65 g (C) m−2 y−1 for AD, ED, AW and EW treatments, respectively. Elevated Ca increased season-long average dry weight (DWS; crown, shoots) by 14% (P = 0.02), whereas deficit irrigation reduced DWS by 7% (P = 0.06), although these values may have been affected by a short but severe pea aphid [Acyrthosiphon pisum (Harris)] infestation. Hence, an elevated-Ca-based improvement in gas exchange properties enhanced growth of a barley crop. 相似文献
979.
Man made electromagnetic irradiation and fields cover now the globe due to the recent extensive propagation of mobile telephony. The increased load affects animals and also plants. Especially birds have been studied. Humans are also sensitive. They are good bioindicators as epidemiological methods are available. Humans can also report symptoms which cannot be directly measured with presently available technologies. The nonionizing irradiation can as the ionizing one break the DNA, damage proteins, even increase the blood brain barrier permeability, disturb the night rest, cause fatigue and hormonal disturbances. An increase of the tumours of human head has been described in correlation with the long term mobile phone use and on that side more exposed. The regulations covering mobile telephony are already about two decades old and need re-evaluation. The multitude of irradiation and the interaction of the different wavelength exposures, i.e., frequency sensitivity is poorly known at present. We should not forget the comparative studies of different species especially those which rely in their lives on electromagnetic orientation physiology. Some countries have issued warnings on the exposures of children. The producers of mobile technology have recently warned the users not to keep those devices in active stage in skin contact. 相似文献
980.
为了对比DIN 75220标准阳光模拟试验与我国海南户外暴露试验,以某型汽车整车和PC、PS标准板为研究对象,对自然曝晒试验和基于DIN 75220标准的整车阳光模拟试验中汽车典型部位微环境、汽车典型部件失效行为以及温度校正太阳辐射量的结果进行了对比研究。分析了2种试验方法中各统计量间的相关关系,进一步结合2种方法下的油漆件色差、内外饰件间缝隙变化结果以及关键部件典型失效问题,提出了适合用于模拟我国海南典型湿热自然环境的定制化阳光模拟试验循环。研究结果表明,基于DIN 75220标准的1个周期整车阳光模拟试验可以反映约80%的湿热自然环境整车曝晒试验3~6个月出现的失效问题。DIN 75220标准中,潮湿气候循环试验可以较好地模拟我国海南湿热自然环境,35个潮湿气候循环可以模拟海南整车自然曝晒1 a。 相似文献