全文获取类型
收费全文 | 268篇 |
免费 | 19篇 |
国内免费 | 46篇 |
专业分类
安全科学 | 16篇 |
废物处理 | 20篇 |
环保管理 | 16篇 |
综合类 | 126篇 |
基础理论 | 56篇 |
污染及防治 | 66篇 |
评价与监测 | 19篇 |
社会与环境 | 5篇 |
灾害及防治 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 14篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 4篇 |
2018年 | 13篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 31篇 |
2014年 | 15篇 |
2013年 | 35篇 |
2012年 | 38篇 |
2011年 | 24篇 |
2010年 | 18篇 |
2009年 | 15篇 |
2008年 | 23篇 |
2007年 | 9篇 |
2006年 | 16篇 |
2005年 | 12篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 15 毫秒
101.
利用崇信县气象观测资料,选用华煤集团新柏煤矿瓦斯浓度观测资料,进行多因子分析,探讨气象条件与矿井瓦斯浓度的关系,选取相关系数绝对值大于0.3的因子,用统计学方法中的逐步回归法进行煤矿区不同回风巷瓦斯浓度预测,建立瓦斯气象条件预警模型,并建立瓦斯气象自动监控预警系统平台,为研究煤矿瓦斯爆炸,减少煤矿安全生产事故的发生,提供科学依据。 相似文献
102.
103.
Pascal Godefroit Lina Golovneva Sergei Shchepetov Géraldine Garcia Pavel Alekseev 《Die Naturwissenschaften》2009,96(4):495-501
A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern
Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous–Tertiary mass extinction
event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest
Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical
data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate
was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high
latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result
of temperature decline, caused or not by the Chicxulub impact. 相似文献
104.
载镁活化天然沸石处理高氟水实验研究 总被引:1,自引:1,他引:0
为了提高沸石对氟的吸附能力,采用氯化镁对活化天然沸石进行改性,分析了除氟剂的性能,确定了除氟剂改性的最佳条件:10%氯化镁溶液,固液比1∶4,pH=7.0,室温以300 r/min的速度振荡改性3h。最佳除氟条件:pH=7.0,室温以300 r/min的速度搅拌反应1.5 h。吸附剂对F-的吸附过程符合Langmuir及Freundlich等温线方程,由D-R模型拟合可知,除氟剂对氟的吸附为物理吸附过程。在最佳反应条件下,水样中氟浓度由2 mg/L降低到0.78 mg/L,符合GB5949-2006《生活饮用水卫生标准》(≤1 mg/L)。 相似文献
105.
某冶炼厂污染场地抽出-处理技术优化方案研究 总被引:2,自引:0,他引:2
本文以某冶炼厂实际污染场地为例,建立了水流和溶质运移耦合模型,在此基础上根据不同的井数、不同的单井抽水量、不同的井间距的组合建立了抽水方案79组,将各抽水方案进行不同权重的加权平均计算,得到的较集中的方案为最佳。此方法得出的方案较其他方法得到的方案优化性强。因此加权平均结合数值模拟方法可为实际工程提供可行性证据。 相似文献
106.
以沈阳沈抚灌区上游指定区域为研究对象,监测分析了停灌十多年来土壤中石油烃污染残留状况;采用单项污染指数法和综合污染指数法评价了采样区域的土壤中石油烃污染现状,同时运用Arcgis软件分析绘制了采样区的单项污染指数分布图。结果表明:采样区域石油烃存在残留和污染现象,按照单项污染指数评价,60%的行政村土壤属于高污染级以上。按照综合污染指数评价,80%的行政村土壤属于重污染级。污染指数分布图显示,离主干灌渠的源头越近,污染越严重。对于土壤石油烃修复效果,旱田作业要好于水田作业。 相似文献
107.
SUMMARY Reclaiming farmland from lakes in China in the 1950s damaged the water quality of many lakes. Tremendous efforts have been made since the late 1990s to restore vegetation around the damaged lakes. This paper examines water quality of Fuxian and Qilu Lakes and land-use characteristics within the two catchments in the high-altitude area of Yunnan Province, China. Landsat TM data acquired in 1989, 1994, 1999 and 2005 were used to extract land use and land cover (LULC) information. Measurements of five water quality indices (WQIs), BOD, COD, pH, TN and TP, for the same period of time were examined. The results showed that the area of residential and forest/shrub increased, whereas that of cropland and barren land decreased from 1989 to 2005 in both catchments. Qilu Lake was much more polluted than Fuxian Lake, and pollution worsened over time for both lakes. The differences in water quality between the two lakes were caused by differences in LULC composition and continued degradation in water quality was caused by intensive farming and urban sprawl. Unless the landscape is converted back to its pre-1950 composition and structure, water quality in both lakes cannot be significantly improved and will continue to threaten sustainable development in the region. 相似文献
108.
为利用一氧化氮(NO)调节作用实现小麦(Tritivum aestivum L.)高产优质之目的,本试验在网室盆栽条件下,以冬春性不同的2个小麦品种(弱春性偃展4110和半冬性周麦18)为试验材料,研究了不同浓度外源NO供体——SNP处理对花后小麦光合生理特性及成熟期产量构成因素的影响。结果表明,不同浓度SNP处理对2种小麦旗叶叶面积、RWC、可溶性糖、总叶绿素含量、WUE、千粒质量、穗粒质量等均有不同程度的促进作用;与对照相比,低浓度SNP(0.075~0.15 mmol.L-1)明显降低2种小麦旗叶枯叶/绿叶值(Y/G),而高浓度(0.30 mmol.L-1)处理则使Y/G值上升。综合分析:本试验条件下,外源NO对半冬性品种周麦18的调控效果优于弱春性品种偃展4110;周麦18以0.30 mmol.L-1SNP处理、偃展4110以0.15mmol.L-1SNP调控对小麦增产较为明显。 相似文献
109.
当工艺操作参数波动较大时,尤其是在开工阶段,杨易造成稳定塔安全阀起跳.分析了安全阀起跳的原因,认为主要原因是稳定塔负荷过大及稳定塔塔顶温度过高,提出了相应的预防安全阀起跳的工艺控制措施. 相似文献
110.
Yukari Suzuki Lina G. Kawaguchi Dulee T. Munidasa Yukihiko Toquenaga 《Behavioral ecology and sociobiology》2009,63(9):1353-1362
We proposed “foundress-max” hypothesis that a bumble bee foundress chooses her nest site to maximize her energy intake rate
from nectar. To examine the hypothesis, we estimated the maximum energy intake rate at each site in the study area and compared
the distribution of the maximum energy intake rates with those of actual nest sites. We also calculated rank correlations
of the maximum energy intake rate with the number of nest-searching foundresses at 54 sites. The nest locations supported
the foundress-max hypothesis, but the number of nest-searching foundresses did not. This could be attributed to the density
of food sites: many food sites may attract many foundresses. Therefore, we subsequently proposed “foundress-sum” hypothesis
that a foundress chooses her nest site to maximize the sum of energy intake rates. The nest locations supported the foundress-max
hypothesis more than the foundress-sum hypothesis. A profitable food site would affect foundresses’ nest site selection. 相似文献