全文获取类型
收费全文 | 921篇 |
免费 | 99篇 |
国内免费 | 188篇 |
专业分类
安全科学 | 130篇 |
废物处理 | 17篇 |
环保管理 | 197篇 |
综合类 | 475篇 |
基础理论 | 127篇 |
环境理论 | 6篇 |
污染及防治 | 88篇 |
评价与监测 | 80篇 |
社会与环境 | 63篇 |
灾害及防治 | 25篇 |
出版年
2024年 | 2篇 |
2023年 | 19篇 |
2022年 | 17篇 |
2021年 | 27篇 |
2020年 | 35篇 |
2019年 | 38篇 |
2018年 | 34篇 |
2017年 | 55篇 |
2016年 | 52篇 |
2015年 | 40篇 |
2014年 | 45篇 |
2013年 | 88篇 |
2012年 | 73篇 |
2011年 | 80篇 |
2010年 | 53篇 |
2009年 | 67篇 |
2008年 | 47篇 |
2007年 | 52篇 |
2006年 | 49篇 |
2005年 | 44篇 |
2004年 | 28篇 |
2003年 | 40篇 |
2002年 | 33篇 |
2001年 | 36篇 |
2000年 | 18篇 |
1999年 | 31篇 |
1998年 | 19篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 14篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1208条查询结果,搜索用时 15 毫秒
921.
通过对220kV输电线路电磁辐射的实际测量和理论计算,研究和讨论了220kV单回路和双回路输电线产生的电磁辐射对环境的影响,并提出降低电磁辐射水平的对策与建议。 相似文献
922.
随着科学技术和社会经济的高速发展,核技术在工业、农业、医疗等领域得到了越来越广泛的应用,但其在带给人类巨大经济效益的同时,也给社会安全带来了潜在的威协,辐射事故时有发生,不仅污染环境,甚至危及人们的身体健康和生命。文中对辐射事故发生的类型、级别以及发生的原因进行了分析,提出了预防和解决的措施。 相似文献
923.
924.
P. Ele Abiama P. Owono Ateba F.H.P. Ekobena 《Journal of environmental radioactivity》2010,101(9):739-743
The aim of this work is to determine the radioactivity concentration of 226Ra, 232Th and 40K in sub-surface (0-5 cm) soil samples collected from Awanda, Bikoué, Ngombas in the southwestern region of Cameroon, to assess their contribution to the external dose exposure relative to the United Nation Scientific Committee on Effects of Atomic Radiation (UNSCEAR) data. An HPGe p-type detector coupled to a multichannel analyzer was used to perform measurements and data processing. The activity concentrations of 226Ra varied from 0.06 ± 0.01 to 0.27 ± 0.02 kBq kg−1 with a mean value of 0.13 ± 0.01 kBq kg−1 wet weight. The activity concentrations of 232Th varied from 0.10 ± 0.01 to 0.70 ± 0.05 kBq kg−1 with a mean value of 0.39 ± 0.03 kBq kg−1 wet weight, and 40K concentrations varied from 0.37 ± 0.02 to 1.53 ± 0.11 kBq kg−1 with a mean value of 0.85 ± 0.07 kBq kg−1 wet weight, respectively. The mean value of outdoor annual effective doses were estimated to be 0.48 mSv y−1, 0.39 mSv y−1 and 0.38 mSv y−1 from Ngombas, Awanda and Bikoué, respectively. The studied areas can be said to have a high background radiation level. 相似文献
925.
926.
The rate constants of sulfamethoxazole (SMX) degradation by ozonation and UV254 radiation were investigated under various parameters including influent ozone gas concentration, initial SMX concentration, UV light intensity, ionic strength, water quality in terms of varying anions (bicarbonate, sulfate and nitrate), humic acid (HA) and pH. The results indicated that the removal of SMX by ozonation and UV254 radiation fitted well to a pseudo first-order kinetic model and the rate constants were in the range of (0.9-9.8) × 10−3 and (1.7-18.9) × 10−3 s−1, respectively. The second-order rate constants of SMX with ozone (kO3), under varying operational parameters, were also determined and varied in the range of (0.60-3.38) ± 0.13 × 105 M−1 s−1. In addition, SMX degradation through UV pretreatment followed by ozonation in the presence of HA was proved to be an effective method which can remove SMX with a low ozone dose. The results suggested that ozonation of SMX was more affected by concentration of influent ozone gas, alkalinity, and HA, while incident UV light intensity, pH, and HA were the dominant factors influencing UV degradation of SMX. 相似文献
927.
湖北省咸宁市光伏电站太阳能资源评价 总被引:2,自引:0,他引:2
为了对无太阳辐射观测的咸宁市进行并网光伏电站太阳能资源综合评价,拟采用水平面太阳辐射气候学推算方法和倾斜面辐射换算方法,即根据武汉站历史资料分月建立总辐射量和直接辐射量与日照百分率的推算方程推算出咸宁逐月太阳辐射各分量,分析其时间变化、资源丰度和稳定性,并基于Klein提出的散射辐射各向同性的假设,计算出该地不同倾斜面年总辐射量和最佳倾角。结果表明:咸宁地区近50 a(1961~2009年)水平面太阳总辐射年总量为4 0914 MJ/m2,该地区属于太阳能资源丰富区,该地辐射形式等级处于散射辐射较多(C)等级,且太阳能资源年变化稳定度较高。正南朝向斜面接受总辐射年总量最大的条件下其最佳倾角为18°,该倾角下斜面年总辐射量为4 2246 MJ/m2,比水平的值高出33%。设计容量为1 500 kWp的光伏阵列若按最佳倾角和方位角安装,每年可发电约132×106 kW·h。太阳辐射各分量的合理推算与多个评价指标的联合应用为光伏电站规划设计提供了科学依据,也为今后类似工作提供了样本。 相似文献
928.
In this study we assessed the degree of copper (Cu) tolerance in two common lichen species (Cladonia furcata and Cladina arbuscula subsp. mitis) that grow on both uncontaminated substrata and the surface of waste heaps from abandoned old Cu-mines. Regardless of their locality, populations of these lichens contain identical strains of photobionts (Asterochloris clade A in C. arbuscula subsp. mitis and clade D in C. furcata). Therefore, it was expected that if there were differences in Cu toxicity or tolerance between populations, that the photobiont could not be a key element of Cu tolerance in these two lichen species. In laboratory experiments samples of both lichen species (from contaminated and control sites) were incubated in Cu solutions (500 μM) for 24 h. We attempted to determine whether Cu tolerance in these lichens was constitutive, or inducible form. Based on measurements of Cu accumulation, chlorophyll a integrity, chlorophyll a fluorescence, photosynthesis, respiration, measurements of the content of thiobarbituric acid reactive substances (TBARS), the content of soluble proteins, reactive oxygen species (ROS) and the amount of extracellular secondary metabolites of both lichens we found that there were no significant differences in the response of all selected populations of both lichen species to short-term exposure to these high levels of Cu. As a result, we conclude that Cu tolerance in these two lichen species is the constitutive rather than the inducible. 相似文献
929.
20个小麦品种对UV-B辐射增强响应的形态学差异 总被引:1,自引:0,他引:1
研究了大田栽培和自然光条件下 ,模拟UV -B辐射增强对 2 0个小麦品种影响的形态学差异。结果表明 ,叶面积指数、株高、节间长、茎基粗对UV -B辐射增强响应具有品种间差异。株高和节间长对UV -B辐射响应具有一致性 ,呈极显著正相关。根据形态响应指数 (MRI) ,耐性品种 (MRI>- 8 5 )为 :辽春 9>文麦 3>大理 90 5 >兰州 80 10 1>绵阳 2 6 >YV 97- 31>毕 90 - 5。敏感品种 (MRI <- 49 4)为 :会宁 18>繁 19>楚雄 880 7>My 94- 9>黔 14>云麦 39>陇春 16。耐性品种具有较小的叶展开角度 ,敏感品种具有较大的叶展开角度。UV -B辐射还不同程度抑制小麦条锈病的发生 相似文献
930.
设计了一种适用于海上救援的便携式海水淡化装置,由制水模块、供能模块、自动控制模块及辅助模块构成,产水量为3 L/d,可满足1人每天所需水量。制水模块采用"AGMD+DCMD"膜蒸馏工艺实现海水淡化,设置预处理工艺保护膜元件;对系统进行了能量核算,利用太阳能板及蓄电池供能,可提供3.6(k W·h)/d电能,保障设备稳定运行;利用PLC及传感器、指示灯等元件,通过制定控制策略、设计控制程序,对装置运行过程进行实时监控,实现一键化自动运行。将各模块有机集成为海上救援海水淡化装置,达到紧凑、重量轻、密封性好、便于海陆携带、操作简单的目的。 相似文献