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911.
Jinbo Wang Jiaping Wang Wei Nie Xuguang Chi Dafeng Ge Caijun Zhu Lei Wang Yuanyuan Li Xin Huang Ximeng Qi Yuxuan Zhang Tengyu Liu Aijun Ding 《Frontiers of Environmental Science & Engineering》2023,17(9):114
912.
The Behaviour of Selenium in Geological Processes 总被引:1,自引:0,他引:1
E. P. Malisa 《Environmental geochemistry and health》2001,23(2):137-158
Selenium contents were analyzed from a total of 244 soil samples collected over different rock types at a sampling density of one sample per 4km2 around Geita gold mining areas, Northwestern Tanzania. Comparisons using literature survey contents of selenium in geological materials and some implications on the selenium in soils are compiled and discussed. Most selenium occurs as simple selenides in small quantities in low temperature hydrothermal deposits devoid of sulphur. It has been observed that to a large extent selenium content is increased more than most trace elements in the upper parts of the Earth perhaps through extraterrestrial deposition. In deep-seated rocks selenium is associated with sulphur but being volatile selenium and sulphur do not behave according to the crystallochemical law. Due to the higher stability of S6+, Se4+ and Se0 separate during migration. Thus, selenium is especially found in deep-seated plutonic rocks where large magma bodies cooled slowly and sulphur is available to precipitate sulphides. Selenium, which occurs with sulphides, is inhomogeneously deposited into continental margins. It is increased during magmatic differentiation and is highest in basic rocks. In magmatic and metamorphic conditions, selenium is found in the crystal structures of sulphides while in pneumatolytic and hydrothermal processes, it is relatively enriched into the late differentiates compared to sulphur. In metamorphic rocks selenium is more widely distributed. Selenium content in soils in the investigated area varies from (0.3–0.5gg–1) in laterite and in black cotton soil 0.4gg–1. Of all volcanic rocks selenium is highest in volcanogenic rocks especially the basalts. Surface waters are enriched in selenium, which they leach from volcanic materials. Selenium in sediments containing clay and organic matter is elevated but the content decreases with increased metamorphism. Selenium in volcanic areas can be used as a pathfinder in prospecting for volcanogenic ore deposits. S/Se ratios are distinct in different rock types and can thus be used to elucidate the origin of rocks, ores, and sediments. 相似文献
913.
Cu(铜)和Zn(锌)是环境中最常见的重金属污染元素,为探究其对白星花金龟幼虫的毒性,采用滤纸接触法、人工土壤法和菌渣培养法研究了高Cu、高Zn对白星花金龟幼虫的生长及氧化胁迫效应。结果表明,滤纸接触法和人工土壤法中试验浓度Cu、Zn对白星花金龟幼虫死亡率无明显影响。菌渣培养法中虫体的取食抑制率和体重增长抑制率均与Cu、Zn浓度呈显著性正相关关系;Cu处理诱导了虫体可溶性蛋白含量的增加,抑制了SOD(超氧化物歧化酶)、GST(谷胱甘肽转移酶)的活性和MDA(丙二醛)的产生,对CAT(过氧化物酶)活性没有显著影响;Zn浓度为3 500和5 000 mg·kg-1的处理组可溶性蛋白含量被显著诱导、MDA含量被显著抑制,浓度为2 000和6 500 mg·kg-1处理组的SOD活性被激活(P0.05),Zn胁迫未对CAT、GST活性造成明显影响。表明Cu、Zn污染对白星花金龟幼虫生长具有毒性效应,在评价高浓度的重金属污染对虫体的毒性作用时,不能仅采用SOD、CAT、GST等指标作为标志物,需要综合其他指标进行分析。 相似文献
914.
三丁基锡对孔雀鱼的毒性效应研究 总被引:11,自引:1,他引:11
采用静态暴露方式研究三丁基锡氯化物(TBTCl)对孔雀鱼的毒性效应.当幼鱼暴露于1.25-7.90μg·l-1的TBTCl 后,出现明显的急性中毒症状,96h的半致死浓度(LC50)为5.82μg·l-1; 成鱼在0.14-3.56μg·l-1浓度下暴露10-30d,TBTCl能诱导雌鱼的肝体指数升高,并使肝脏和脾脏组织的显微结构发生明显的病理变化,毒害作用具有明显的剂量-效应和时间-效应关系.表明肝体指数以及肝脏、脾脏等组织的病理学变化可以作为评估三丁基锡等环境污染物的生物指标. 相似文献
915.
廊道效应与城市景观结构 总被引:25,自引:0,他引:25
宗跃光 《城市环境与城市生态》1996,9(3):21-25
根据景观学原理,本文将城市廊道分为两类,人工廊道与自然廊道,并着重分析城市廊道的场效应,研究表明,廊道效应产生的实质在于廊道效益是距离的函数,因而可用指数衰减曲线表示,从理论上分析,人工廊道与自然廊道场效应的分界点即综合效益极大点,自然廊道在两条人工廊之间存在的合理依据是:至少存在两个分别与两条指数衰减曲线相交的综合效益极值点。根据廊道效应原 文对北京古代传统规划格局进行分析,发生在天人鸽 与择中 相似文献
916.
为探究成都市大气环境中气象因子交互作用对臭氧(8h浓度平均最大值,统一用O3表示)浓度变化的影响特征,利用成都市2014~2019年逐日大气污染物资料以及同期的气象资料,采用广义相加模型(generalized additive models,GAMs)分析气象因子对O3浓度变化的影响效应.结果表明,单影响因素的GAMs模型中,O3浓度与最高气温、日照时数、相对湿度、风速、降水量、最大混合层厚度(maximum mixed depth,MMD)和通风系数(ventilation coefficient,VC)间均呈非线性关系,无论全年还是夏季,最高气温、日照时数、MMD和相对湿度对O3浓度影响均较大,值得注意的是,夏季相对湿度和降水量对O3浓度变化的影响较全年更加显著.在构建O3浓度变化的多气象因子GAMs模型中,除平均风速以外的其他气象因子共同作用对O3浓度变化有显著影响,就全年而言,构建的GAMs模型判定系数(R2 相似文献
917.
Doron Lavee 《国际发展与全球生态学杂志》2018,25(8):683-695
This paper aims to identify the most suitable and economically feasible policy measures to reduce concentrations of particulate matter (PM) and ozone (O3) in Israel. It describes a comprehensive methodology that takes into account the effects of PM and O3 and describes the overall costs and benefits expected from their reduction. Cost-benefit analysis of a series of proposed policy measures allows us to identify and recommend those that are most feasible and effective. These policy measures have a significant impact on reducing air pollution on one hand, while constituting the highest net benefit to the economy on the other. 相似文献
918.
Threats to biodiversity from cumulative human impacts in one of North America's last wildlife frontiers 下载免费PDF全文
Nancy Shackelford Rachel J. Standish William Ripple Brian M. Starzomski 《Conservation biology》2018,32(3):672-684
Land‐use change is the largest proximate threat to biodiversity yet remains one of the most complex to manage. In British Columbia (BC), where large mammals roam extensive tracts of intact habitat, continued land‐use development is of global concern. Extant mammal diversity in BC is unrivalled in North America owing, in part, to its unique position at the intersection of alpine, boreal, and temperate biomes. Despite high conservation values, understanding of cumulative ecological impacts from human development is limited. Using cumulative‐effects‐assessment (CEA) methods, we assessed the current human footprint over 16 regional ecosystems and 7 large mammal species. Using historical and current range estimates of the mammals, we investigated impacts of human land use on species’ persistence. For ecosystems, we found that bunchgrass, coastal Douglas fir, and ponderosa pine have been subjected to over 50% land‐use conversion, and over 85% of their spatial extent has undergone either direct or estimated indirect impacts. Of the mammals we considered, wolves were the least affected by land conversion, yet all species had reduced ranges compared with historical estimates. We found evidence of a hard trade‐off between development and conservation, most clearly for mammals with large distributions and ecosystems with high levels of conversion. Rather than serve as a platform to monitor species decline, we strongly advocate these data be used to inform land‐use planning and to assess current conservation efforts. More generally, CEAs offer a robust tool to inform wildlife and habitat conservation at scale. 相似文献
919.
920.
Endocrine disruptors in bottled mineral water: total estrogenic burden and migration from plastic bottles 总被引:1,自引:1,他引:0
Martin Wagner Jörg Oehlmann 《Environmental science and pollution research international》2009,16(3):278-286
Background, aim, and scope Food consumption is an important route of human exposure to endocrine-disrupting chemicals. So far, this has been demonstrated
by exposure modeling or analytical identification of single substances in foodstuff (e.g., phthalates) and human body fluids
(e.g., urine and blood). Since the research in this field is focused on few chemicals (and thus missing mixture effects),
the overall contamination of edibles with xenohormones is largely unknown. The aim of this study was to assess the integrated
estrogenic burden of bottled mineral water as model foodstuff and to characterize the potential sources of the estrogenic
contamination.
Materials, methods, and results In the present study, we analyzed commercially available mineral water in an in vitro system with the human estrogen receptor
alpha and detected estrogenic contamination in 60% of all samples with a maximum activity equivalent to 75.2 ng/l of the natural
sex hormone 17β-estradiol. Furthermore, breeding of the molluskan model Potamopyrgus antipodarum in water bottles made of glass and plastic [polyethylene terephthalate (PET)] resulted in an increased reproductive output
of snails cultured in PET bottles. This provides first evidence that substances leaching from plastic food packaging materials
act as functional estrogens in vivo.
Discussion and conclusions Our results demonstrate a widespread contamination of mineral water with xenoestrogens that partly originates from compounds
leaching from the plastic packaging material. These substances possess potent estrogenic activity in vivo in a molluskan sentinel.
Overall, the results indicate that a broader range of foodstuff may be contaminated with endocrine disruptors when packed
in plastics. 相似文献