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921.
溶藻细菌对富营养化水体藻类群落结构的影响 总被引:3,自引:0,他引:3
向富营养化水体投放3株溶藻细菌(蜡状芽孢杆菌(Bacillus cereus)L7、L8和短小芽孢杆菌(Bacillus pumilus)L18)的菌液.在试验期内,3株溶藻细菌显示出很好的控藻效果,使叶绿素a(Chl-a)和藻类密度分别比初始值降低87%以上和72%以上;藻类Shannon-Weaver多样性指数维持在2~3,Pielous均匀度指数介于0.60~0.81,其中,溶藻细菌L7效果最明显.而未投加菌液的水体Chl-a未发生明显上升,但藻类密度自9.55×104个/mL上升到2.09×105个/mL,藻类Shannon-Weaver多样性指数由2.17降到1.11,Pielous均匀度由0.60降到0.33.3株溶藻细菌并非简单地杀灭水体中的全部或某些藻类,而是能明显地调节藻类群落结构,使其朝着较为稳定的方向发展,在修复藻型富营养化水体水生生态系统方面有很好的应用前景. 相似文献
922.
923.
Liu J Cox SB Beall B Brunjes KJ Pan X Kendall RJ Anderson TA McMurry ST Cobb GP Smith PN 《Chemosphere》2008,71(10):1945-1949
We evaluated the use of the gas exchange rate as an ecologically relevant indicator of chemical stress in avian embryos/eggs. Northern bobwhite quail (Colinus virginianus) were exposed to octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) via feed containing nominal concentrations of 0, 12.5, 50.0, and 125.0 mg kg(-1). Metabolic rates (oxygen consumption) of developing quail eggs were then measured via respirometry to examine potential effects of HMX exposure. Metabolic rates were examined on 5, 9, and 21 d of incubation. Next, concentrations of HMX in embryos/eggs were determined by liquid chromatography-mass spectrometry. Mean (+/-SE) concentrations of HMX in eggs were 21.0+/-5.9, 1113+/-79.0, 3864+/-154.0, and 7426+/-301.1 ng g(-1) in control, low, medium and high dose groups, respectively. There were significant differences in oxygen consumption among the three embryo ages, however differences among the ages were not consistent among dose groups (age x dose group interaction p<0.0001). Oxygen consumption rates did not vary as a function of HMX in embryos (p=0.18). No evidence was observed for alterations of in ovo metabolic rates associated with HMX exposure. 相似文献
924.
以涂有CeO2-ZrO2固溶体的堇青石蜂窝状陶瓷为载体,用浸渍法制备堇青石蜂窝陶瓷型整体La0.8Sr0.2MnO3催化剂,测试了该催化剂催化燃烧各类VOCs的特性。研究表明,VOCs催化燃烧的难易程度为:含氯烃〉烷烃〉酸〉芳烃〉酮〉酯〉醇〉醛。La0.8Sr0.2MnO3催化剂对含氧有机化合物具有较好的催化活性,完全燃烧温度均在280℃之内。通过关联VOCs的理化性质,发现VOCs在La0.8Sr0.2MnO3催化剂上的反应活性与VOCs分子中最弱C—H键键能和VOCs分子极性密切联系。 相似文献
925.
Yuepeng Pan Yuesi Wang Jinyuan Xin Guiqian Tang Tao Song Yinghong Wang Xingru Li Fangkun Wu 《Atmospheric environment (Oxford, England : 1994)》2010,44(19):2350-2357
Dissolved organic carbon (DOC) was measured in 483 precipitation samples collected at 10 sites in Northern China from December 2007 to November 2008. The annual volume-weighted mean (VWM) concentrations and wet deposition fluxes of DOC for 10 sites ranged from 2.4 to 3.9 mg C/L and 1.4 to 2.7 g C m?2 yr?1, respectively. The proportion of DOC to total organic carbon (TOC) was 79% on average, suggesting that a significant fraction of TOC was present as insoluble particulate organic carbon. Due to intensive domestic coal use for house heating and smaller dilution of scavenged organic carbon, higher VWM concentrations of DOC were observed during winter and spring than during summer and autumn. When precipitation events were classified via air mass back-trajectories, the mixed trajectories from SE and NW always corresponded to significantly higher DOC than those from SE or NW alone, coinciding with the centre of a low pressure system moved eastward and the wind direction changed from southeast to northwest. The results also showed that each site had a similar seasonal variation for DOC wet deposition flux. The largest flux occurred during the rainy season, and the lowest flux appeared during winter months. The product of the TC/DOC ratio and the DOC flux yielded an average TC wet deposition flux of 3.2 g C m?2 yr?1 in Northern China, accounting for 8.6% and 22% of the carbon sink magnitude (37 g C m?2 yr?1) in terrestrial ecosystems and anthropogenic carbon emissions (14 g C m?2 yr?1), respectively. This indicates that atmospheric wet deposition of TC is a significant carbon flux that cannot be neglected in regional models of the carbon cycle, and should be considered along with dry deposition in the removal mechanism for carbon from regional atmosphere. 相似文献
926.
Huang Guolong Yao Jiachao Pan Weilong Wang Jiade 《Environmental science and pollution research international》2016,23(18):18288-18295
Environmental Science and Pollution Research - Effluents after biochemical treatment contain pollutants that are mostly non-degradable. Based upon previous pilot-scale test results, an... 相似文献
927.
Wenguo Wang Chuang Yang Xiaoyu Tang Xinjiao Gu Qili Zhu Ke Pan Qichun Hu Danwei Ma 《Environmental science and pollution research international》2014,21(24):14202-14210
Growing common duckweed Lemna minor L. in diluted livestock wastewater is an alternative option for pollutants removal and consequently the accumulated duckweed biomass can be used for bioenergy production. However, the biomass accumulation can be inhibited by high level of ammonium (NH4 +) in non-diluted livestock wastewater and the mechanism of ammonium inhibition is not fully understood. In this study, the effect of high concentration of NH4 + on L. minor biomass accumulation was investigated using NH4 + as sole source of nitrogen (N). NH4 +-induced toxicity symptoms were observed when L. minor was exposed to high concentrations of ammonium nitrogen (NH4 +-N) after a 7-day cultivation. L. minor exposed to the NH4 +-N concentration of 840 mg l?1 exhibited reduced relative growth rate, contents of carbon (C) and photosynthetic pigments, and C/N ratio. Ammonium irons were inhibitory to the synthesis of photosynthetic pigments and caused C/N imbalance in L. minor. These symptoms could further cause premature senescence of the fronds, and restrain their reproduction, growth and biomass accumulation. L. minor could grow at NH4 +-N concentrations of 7–84 mg l?1 and the optimal NH4 +-N concentration was 28 mg l?1. 相似文献
928.
Kohei Ikeda Kazuyo Yamaji Yugo Kanaya Fumikazu Taketani Xiaole Pan Yuichi Komazaki 《Journal of the Air & Waste Management Association (1995)》2014,64(4):445-452
The authors analyze the sensitivities of source regions in East Asia to PM2.5 (particulate matter with an aerodynamic diameter of ≤2.5 µm) concentration at Fukue Island located in the western part of Japan by using a regional chemical transport model with emission sensitivity simulations for the year 2010. The temporal variations in PM2.5 concentration are generally reproduced, but the absolute concentration is underestimated by the model. Chemical composition of PM2.5 in the model is compared with filter sampling data in spring; simulated sulfate, ammonium, and elemental carbon are consistent with observations, but mass concentration of particulate organic matters is underestimated. The relative contribution from each source region shows the seasonal variation, especially in summer. The contribution from central north China (105°E–124°E, 34°N–42°N) accounts for 50–60% of PM2.5 at Fukue Island except in summer; it significantly decreases in summer (18%). Central south China (105°E–123°E, 26°N–34°N) has the relative contribution of 15–30%. The contribution from the Korean Peninsula is estimated at about 10% except in summer. The domestic contribution accounts for about 7% in spring and autumn and increases to 19% in summer. We also estimate the relative contribution to daily average concentration in high PM2.5 days (>35 μg m?3). Central north China has a significant contribution of 60–70% except in summer. The relative contribution from central south China is estimated at 46% in summer and about 30% in the other seasons. The contributions from central north and south China on high PM2.5 days are generally larger than those of their seasonal mean contributions. The domestic contribution is smaller than the seasonal mean value in every season; it is less than 10% even in summer. These model results suggest that foreign anthropogenic sources have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.
Implications: The contribution from several source regions in East Asia to PM2.5 concentration at Fukue Island, a remote island located in the western part of Japan and close to the Asian continent, is estimated using a three-dimensional chemical transport model. The model results suggest that PM2.5 that is attributed to foreign anthropogenic sources have a larger contribution than that of domestic pollution and have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island. 相似文献
929.
930.