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241.
The long‐term integrity of protected areas (PAs), and hence the maintenance of related ecosystem services (ES), are dependent on the support of local people. In the present study, local people's perceptions of ecosystem services from PAs and factors that govern local preferences for PAs are assessed. Fourteen study villages were randomly selected from three different protected forest areas and one control site along the southern coast of Côte d'Ivoire. Data was collected through a mixed‐method approach, including qualitative semi‐structured interviews and a household survey based on hypothetical choice scenarios. Local people's perceptions of ecosystem service provision was decrypted through qualitative content analysis, while the relation between people's preferences and potential factors that affect preferences were analyzed through multinomial models. This study shows that rural villagers do perceive a number of different ecosystem services as benefits from PAs in Côte d'Ivoire. The results based on quantitative data also suggest that local preferences for PAs and related ecosystem services are driven by PAs' management rules, age, and people's dependence on natural resources.  相似文献   
242.
干旱半干旱地区重污染河流水质水量响应关系预测研究   总被引:1,自引:1,他引:0  
朱磊  李怀恩  李家科 《环境科学学报》2012,32(10):2617-2624
通过建立渭河关中段水质水量响应关系程序,对渭河关中段规划水平年(2020年)不同来水频率(P)条件下丰水期、平水期、枯水期的水质水量响应关系进行定量化分析研究.结果表明,规划水平年丰水期、平水期、枯水期同一断面在不同来水频率下COD和NH+4-N从小到大的排序均为:P=25%、P=50%、P=75%、P=95%.规划水平年丰水期、平水期、枯水期的COD在林家村断面至兴平断面较小,低于地表水环境质量标准(GB3838—2002)Ⅴ类水标准,而后逐渐开始升高,南营断面COD涨幅较大,至咸阳断面升至最高,后又逐渐减低;规划水平年丰水期、平水期、枯水期的NH+4-N在林家村断面至兴平断面较小,低于地表水环境质量标准Ⅴ类水标准,而后逐渐开始升高,咸阳断面NH+4-N增幅较大,至树园断面升至最高.  相似文献   
243.
杭州西湖富营养化防治设施最佳运行方式探讨   总被引:3,自引:0,他引:3  
通过分析西湖富营养化主要影响因素及其防治措施的时效性,探讨现有各种防治设施的最佳运行方式,以降低治理费用、提高治理效果。  相似文献   
244.
王相男  张喆  刘方青 《环境科学》2024,45(3):1315-1327
针对天山北坡城市群开展PM2.5浓度时空分布特征和影响因素分析,对区域经济建设和环境保护具有积极的意义.通过地理加权回归(GWR)模型,利用MCD19A2气溶胶产品结合气象因子,反演得到天山北坡城市群2015~2021年3~11月的PM2.5浓度时空分布,继而实现变化趋势和影响因素分析.结果如下:①研究区PM2.5浓度高值主要分布在天山北麓和古尔班通古特沙漠之间的绿洲城市群地带,呈现“四周低,中间高”和“西低东高”的空间分布特征,2015~2021年研究区的ρ(PM2.5)年均值为16.98 μg·m-3,高值主要聚集在乌鲁木齐市市区部分,并向昌吉市和阜康市延伸递减;ρ(PM2.5)月均值分布规律与年均一致,但存在季节差异,表现为:秋季(20.32 μg·m-3)>春季(18.25 μg·m-3)>夏季(12.47 μg·m-3),春季和冬季聚集现象会更明显;②研究区PM2.5浓度年均值在2015~2021年呈现下降趋势,3~10月均值同样表现为下降趋势,仅11月表现为略有升高;从PM2.5浓度变化趋势空间分布分析,下降集中在主要城市市区部分,尤其是乌鲁木齐市市区部分及其周边地区减少幅度最大,变化最为剧烈;③研究区气温、气压与PM2.5浓度呈现正相关效应,而相对湿度,风速,大气边界层高度,降水量与PM2.5浓度呈现负相关效应;各因子影响程度从高向低排列为:大气边界层高度>相对湿度>气压>气温>风速>降水量.  相似文献   
245.
The Eastern Arc Mountains (EAMs) of Tanzania and Kenya support some of the most ancient tropical rainforest on Earth. The forests are a global priority for biodiversity conservation and provide vital resources to the Tanzanian population. Here, we make a first attempt to predict the spatial distribution of 40 EAM tree species, using generalised additive models, plot data and environmental predictor maps at sub 1 km resolution. The results of three modelling experiments are presented, investigating predictions obtained by (1) two different procedures for the stepwise selection of predictors, (2) down-weighting absence data, and (3) incorporating an autocovariate term to describe fine-scale spatial aggregation. In response to recent concerns regarding the extrapolation of model predictions beyond the restricted environmental range of training data, we also demonstrate a novel graphical tool for quantifying envelope uncertainty in restricted range niche-based models (envelope uncertainty maps). We find that even for species with very few documented occurrences useful estimates of distribution can be achieved. Initiating selection with a null model is found to be useful for explanatory purposes, while beginning with a full predictor set can over-fit the data. We show that a simple multimodel average of these two best-model predictions yields a superior compromise between generality and precision (parsimony). Down-weighting absences shifts the balance of errors in favour of higher sensitivity, reducing the number of serious mistakes (i.e., falsely predicted absences); however, response functions are more complex, exacerbating uncertainty in larger models. Spatial autocovariates help describe fine-scale patterns of occurrence and significantly improve explained deviance, though if important environmental constraints are omitted then model stability and explanatory power can be compromised. We conclude that the best modelling practice is contingent both on the intentions of the analyst (explanation or prediction) and on the quality of distribution data; generalised additive models have potential to provide valuable information for conservation in the EAMs, but methods must be carefully considered, particularly if occurrence data are scarce. Full results and details of all species models are supplied in an online Appendix.  相似文献   
246.
Abstract:  Habitat destruction is one of the greatest threats to primates worldwide. To understand the impact of forest logging on the habitat use of primates in temperate mixed forest, we compared the range, habitat used, population size, and diet of a troop (ERT) of Sichuan snub-nosed monkeys ( Rhinopithecus roxellana ) in the Qinling Mountains before (1989), during (1997), and after (2002–2003) commercial logging. Logging significantly changed the composition of the forest and the food supply for the troop. Some areas were heavily logged and formed patches in the forest that lacked canopy cover. The troop moved 7 km away from their original range when logging took place and returned to their original range after logging stopped, but they avoided heavily logged areas that lacked canopy cover. Their movement indicated some degree of site fidelity in this species. Diet and home range changed after logging, but the population size remained stable, which suggests that this species has some ability to adapt to habitat changes. Our results may reflect a natural flexibility in primates to adapt to the changing food resources in temperate areas with marked seasonal variations in food availability and distribution. This flexibility may have contributed to their higher degree of resilience to habitat alterations caused by human activities compared with tropical forest primates that have a more specialized diet. Our findings provide important baseline information that will help decision makers in their efforts to conserve primates, especially in temperate regions, and to sustainably manage primate habitat.  相似文献   
247.
The aim of this work was to report on imidacloprid [IUPAC name 1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] residues in some vegetables, fruits, and water samples collected from the West Bank, Palestine, in 1998 and 1999. Imidacloprid and its derivatives in the study samples were extracted by methanol/water and oxidized into 6-chloronicotinic acid and subsequently derivatized into 6-chloronicotinic acid trimethylsilyl ester before being determined by GC/MS. Imidacloprid residues were detected in more than half of the analyzed samples. The highest and lowest imidacloprid concentrations were found in eggplant (0.46 mg/kg) and green beans (0.08 mg/kg), respectively. An increase of 11–120% in imidacloprid concentration in the 1999 samples was observed when compared with those of 1998. This may suggest imidacloprid accumulation in the soil and/or increased use by local farmers. The imidacloprid residue concentrations in several crops were found to exceed the CODEX maximum residue limit.  相似文献   
248.
以西部山区的缩影川西为研究对象,利用交通矢量化数据和自然社会经济数据,在GIS软件支持下,探讨"十五"计划以来不同时期川西山区交通通达性与GDP的海拔空间分异性及其相关关系。结果表明:(1)2000~2013年间川西山区交通通达性有了显著提高,各县通达水平两级分化有所减弱,高值区集中于攀西城市群,低值区主要位于甘孜州;(2)川西山区GDP与交通水平均具有较为明显的海拔梯度分异,表现为中低海拔区中海拔区高海拔区高原区,呈现出"反自然梯度特征";(3)从整体上看,川西山区通达性指数与GDP存在显著正向关联且关联程度不断加强,交通主干线显现出更为明显的经济促进作用,而边缘化的地理区位不利于地区对外开放,阻滞了经济发展;(4)不同时期各海拔区交通通达性及其构成要素与GDP的关联方向和程度差异较大。  相似文献   
249.
秦岭南部地区地形及气候条件复杂,作为油菜主要种植区之一,研究其农业气候资源的变化特征及其对油菜的影响,可以为该区有效利用农业气候资源、合理安排农事活动提高油菜生产提供实践参考。以1960~2014年秦岭南部33个站点的逐日气象数据和近25a各省市统计年鉴资料,通过滑动平均、线性倾向估计、灰色关联分析等方法,研究秦岭南部农业气候资源的时空变化特征及对油菜产量的影响。结果表明:(1)近55a来,秦岭南部地区油菜生长季内平均气温和≥5℃积温呈上升趋势,平均速率分别为0.2、29.3℃/10 a,冻害指数、降水量、开花期降水量和相对湿度与日照时数都呈减少趋势,平均每10 a分别减少0.3、14.8 mm、1.4 mm、0.6%、32.2 h。(2)近55a来研究区油菜生长季内平均气温与≥5℃积温的多年平均空间分布都表现为由西南向东北方向递减,冻害指数的空间变化与二者相反,表明越冬期极端最低气温值在空间上由西南向东北逐渐减小;其水资源指标多年平均空间分布由南向北递减,日照时数则由西南向东北递增。(3)1960~2014年秦岭南部油菜生长季内平均气温与≥5℃积温在空间上均呈极显著的增加趋势,研究区西部变化幅度较小,东部变化幅度较大,冻害指数的空间变化趋势与二者相同;水资源与日照时数在空间上均呈极显著的减少趋势,只有少数站点表现为极显著的增加趋势,而日照时数在研究区东部变化幅度相对较大,其余区域变化幅度相对较小。总体上,平均气温和≥5℃积温高值区的变化幅度小,低值区变化幅度大,其他指标与之相反。(4)近25a来秦岭南部油菜气候产量呈不明显的上升趋势,平均速率为3.79 kg/(a·hm~2),其空间变化幅度差异大,且大部分站点的变化趋势均不显著;由关联度得作用于各区域油菜气候产量的主要影响因子存在差异。各农业气候资源指标的变化幅度越大,对油菜单产的可能影响相对较大。  相似文献   
250.
西湖与青山水库底栖动物群落的研究   总被引:4,自引:0,他引:4  
通过对杭州市的两个主要水体西湖和青山水库的底栖动物群落包括种类组成、优势种群、生物量等的比较研究。西湖和青山水库底栖动物群落主要由寡毛类和摇蚊幼虫组成 ,存在适应低溶氧、耐有机污染的种群。从底栖动物群落生态学角度评价了西湖和青山水库水体的营养化程度。  相似文献   
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