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671.
672.
爆炸及其危险性分析与评价 总被引:1,自引:0,他引:1
了解爆炸发生的机理,对危险场所进行爆炸危险性评价是预防爆炸事故发生的有效措施。本文对爆炸及典型的爆炸危险性评价方法进行了简略介绍。 相似文献
673.
1994年世界重要灾害地震32条(其中中国4条),因地震死亡者2400人(中国5人),受伤15500人(中国1149人),其中最严重的5次地震造成约320亿美元的经济损失。全球6级以上地震134次(其中7级以上地震15次),地震多发生于环太洋地震带,尤以西太平洋地区地震活动性较高,并有增强的趋势。 相似文献
674.
山东省地下水位下降引发的灾害及减灾对策 总被引:1,自引:0,他引:1
近二十年来山东省经济迅速发展与水资源匮乏的矛盾不断加剧。超量开采地下水导致地下水位持续的急剧下降,其结果引发了地裂缝、地面塌陷、海(咸)水入侵、生态环境恶化等一系列人为自然灾害。本文分析了这些灾害的基本特征并指出解决水资源不足是促进山东省经济持续高速发展并减轻地下水位下降灾害的根本措施。 相似文献
675.
676.
Effect of elemental sulphur on solubility of soil heavy metals and their uptake by maize 总被引:7,自引:0,他引:7
A pot experiment was conducted to study the influence of elemental sulphur (S) on solubility of soil Pb, Zn and Cd and uptake by maize (Zea mays L.). Two rates of elemental sulphur (S) applied at 0 (S0) and 200 (S200) mmol kg(-1) soil with three rates of each heavy metal at Pb, 0 (Pb0), 200 (Pb200), 400 (Pb400) mg kg(-1) soil, Zn, 0 (Zn0), 100 (Zn100), 200 (Zn200) mg kg(-1) soil and Cd, 0 (Cd0), 50 (Cd50), 100 (Cd100) mg kg(-1) soil, respectively. The result showed that with S application at 200 mmol S kg(-1), soil pH decreased about 0.3 unit and the solubility of the Zn and Cd was significantly increased, but the solubility of Pb had no significant influence. The concentration of Pb, Zn and Cd in maize shoots and roots were increased with increasing rates of heavy metals. However, the concentration of Zn and Cd in shoots and roots were higher with application of S rather than without S but no significant difference was found for Pb. The highest concentration of Zn in the shoots was 2.3 times higher with application of S rather than without at the same rate of Zn, 200 mg kg(-1). Plant biomass was also significantly affected by the application of S and of heavy metals. With heavy metal addition, the shoot and root biomass were decreased with the rates of those of heavy metals increased either with or without application of S. However, the shoot biomass was significantly decreased with S application at the same rate of heavy metals except that with Zn addition. The removal of Cd and Pb by maize uptake and accumulation with application of S had no significant increase compared to that without, but the removal Zn by maize uptake from the soil increased by application of S, 90.9 microg plant(-1) contrast to 25.7 microg plant(-1) at Zn200 within a growth period of only 40 days. 相似文献
677.
In a non-chiral environment,the enantiomers of a racemate possessed the identical physico-chemical properties,but in the biological systems they possessed different activities.Considering that the involvement of oxidative damage has been implicated in the toxicities of various pesticides,this study investigated the possibility of enantioselective oxidative stress and cytotoxicity induction by acetofenate (AF) which contains an asymmetrical center on PC12 cells.The results of the cytotoxicity assay indicated that S-(+)-AF presented more toxic effects than R-(-)-AF and (±)-AF.It also demonstrated that S-(+)-AF possessed the strongest effects in induction of reactive oxygen species (ROS) production,decrease in superoxide dismutase (SOD) and catalase (CAT) activities,and increase in malondialdehyde (MDA) level.These results suggested that AF and its enantiomers could induce enantioselective cytotoxicity in PC12 cells mediated by oxidative stress.Therefore,the assessment in environmental safety and new chiral pesticide development should consider enantioselectivity. 相似文献
678.
武汉市郊典型利用方式下土壤磷素特征及流失风险分析 总被引:3,自引:1,他引:2
当前地表水体环境问题日益突出,磷素作为水体富营养化的关键控制因子而备受关注。本研究通过实地采样分析,研究了武汉市郊区典型利用方式下土壤磷素形态剂含量特征,并分析了其流失风险。结果表明:不同利用方式下的土壤磷素水平差异较大,各形态磷水平排序是蔬菜地稻田常规旱地苗圃地;武汉城郊0~20cm表层土壤全磷(TP)含量为255.4~1763.1mg/kg,平均值为975.4mg/kg;土壤有效磷(Olsen-P)为1.3~164.2mg/kg,平均值为56.4mg/kg;藻类有效磷(NaOH-P)含量为33.4~910.7mg/kg,平均值为204.0mg/kg;土壤Olsen-P为56.0mg/kg可作为武汉市郊区土壤磷素流失的临界值,且超过该临界值的土样有34.9%,其中有93.3%采自蔬菜地,表明各利用方式下蔬菜地土壤磷素流失风险最高。 相似文献
679.
With the increasing use of synthetic pyrethroids (SPs), the significance of ecological safety and health risk is an emerging concern. In this study, we evaluated the chronic aquatic toxicity of cis-bifenthrin (cis-BF) in Daphnia magna and its cytotoxicity in Chinese hamster ovary (CHO) cells as well as human cervical carcinoma (Hela) cells. Chronic aquatic toxicity tests showed that cis-BF could significantly affect the reproduction of D. magna. The lowest observed effective concentration and the non-observed effective concentration of cis-BF to D. magna were 0.02 and 0.01 μg/L, respectively, and the chronic value was 0.014 μg/L. The intrinsic rate of natural increase was significantly decreased (p < 0.05) to 0.02 μg/L. The cytotoxicity assay demonstrated that cis-BF decreased cell viability in CHO and Hela cells in a concentration-and time-dependent manner. The IC50 values for Hela and CHO cells were 4.0 × 10−5 and 3.2 × 10−5 mol/L, respectively. Together, these results indicated that cis-BF induced chronic toxicity in both aquatic invertebrate animals and mammalian cells. These findings assist in understanding the impact of SPs on health and environmental safety. Considering the wide spectrum of SPs, a more comprehensive understanding of the negative effects is indispensible for planning future application and regulation of these pesticides. 相似文献
680.
基于Landsat TM/ETM+的天津城区及滨海新区热岛效应时空变化研究 总被引:2,自引:0,他引:2
利用1987年、1998年、2004年和2008年4景Landsat TM/ETM+数据的热红外波段数据反演天津市地表亮温,并对绝对亮温值进行归一化处理得到相对亮温。通过对相对亮温分布图进行时空分析可知,自1987年到2008年,天津市热岛效应主要发生在中心城区、滨海新区以及道路沿线等区域。热岛范围在加大,强度也在增加。中心城区热岛效应不断加剧,滨海新区的热岛效应则从无到有,从弱到强,变化十分明显。并分析了热岛现象产生和异常的原因,有降水变化、农作物收割、公路建设和建成区增加。 相似文献