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891.
Jin Zhang Fanhao Song Tingting Li Kefu Xie Huiying Yao Baoshan Xing Zhongyu Li Yingchen Bai 《环境科学学报(英文版)》2020,32(4):310-320
Simulated photo-degradation of fluorescent dissolved organic matter(FDOM) in Lake Baihua(BH) and Lake Hongfeng(HF) was investigated with three-dimensional excitationemission matrix(3 DEEM) fluorescence combined with the fluorescence regional integration(FRI),parallel factor(PARAFAC) analysis,and multi-order kinetic models.In the FRI analysis,fulvic-like and humic-like materials were the main constituents for both BH-FDOM and HF-FDOM.Four individual components were identified by use of PARAFAC analysis as humic-like components(C1),fulvic-like components(C2),protein-like components(C3) and unidentified components(C4).The maximum 3 DEEM fluorescence intensity of PARAFAC components C1-C3 decreased by about 60%,70% and 90%,respectively after photo-degradation.The multi-order kinetic model was acceptable to represent the photo-degradation of FDOM with correlation coefficient(R_(adj)~2)(0.963-0.998).The photo-degradation rate constants(k_n) showed differences of three orders of magnitude,from 1.09 x 10~(-6) to 4.02 x 10~(-4) min-1,and half-life of multi-order model(T_(1/2)~n)ranged from 5.26 to 64.01 min.The decreased values of fluorescence index(FI) and biogenic index(BI),the fact that of percent fluorescence response parameter of Region I(P_(Ⅰ,n)) showed the greatest change ratio,followed by percent fluorescence response parameter of Region II(P_(Ⅱ,n),while the largest decrease ratio was found for C3 components,and the lowest T_(1/2)~n was observed for C3,indicated preferential degradation of protein-like materials/components derived from biological sources during photodegradation.This research on the degradation of FDOM by 3 DEEM/FRI-PARAFAC would be beneficial to understanding the photo-degradation of FD OM in natural environments and accurately predicting the environmental behaviors of contaminants in the presence of FDOM. 相似文献
892.
大气臭氧总量的一个统计计算方法 总被引:3,自引:0,他引:3
根据大气臭氧和太阳紫外辐射的观测资料,利用相关分析,得到了计算臭氧总量的一个统计计算方法,并计算了1991年北京地区晴天和实际天然条件下臭氧总量的月平均值,计算结果表明,计算值与观测值吻合得比较好,计算值与观测值相对偏差的平均值小于2.5%,大气中的光化学反应是影响臭氧总量的主要因子。 相似文献
893.
Spatial distribution and ecological risk assessment of heavy metals in surface sediments from a typical plateau lake wetland, China 总被引:18,自引:0,他引:18
Junhong Bai Baoshan CuiBin Chen Kejiang ZhangWei Deng Haifeng GaoRong Xiao 《Ecological modelling》2011,222(2):301-306
Surface sediment (0-15 cm) samples were collected from 31 different grid points throughout the Yilong Lake in April 2004. Samples were subjected to a total digestion technique and analyzed for As, Cd, Cr, Pb, Ni, Cu, and Zn in order to study spatial distribution characteristics based on Kriging method and assess their ecological risks posed by these heavy metals. Results showed that the mean concentrations of these heavy metals were lower than potential effect levels. Patches of higher heavy metal concentrations occurred in the inflow area of the Cheng River and northeast area nearby the road and railway. The higher concentrations of As and Cr also appeared in the east area (lake outlet), while the patches of lower concentrations were uniformly distributed at the southwest corner between Luosewan and Xiaoguoxi. The heavy metal loads such as As, Cd and Pb might come from the common sources due to industrial sewage and traffic pollution, while higher concentrations of Ni, Cr, and Zn in these sediments were dominated by parent rocks. However, Cu originated from both sources. Sediments with respect to As, Cd and Cu were grouped below the effect range low (ERL) at all sites, and with respect to Cr and Pb were grouped into the range from ERL to the effect range median (ERM) at more than 50% of sampling sites. The mean heavy metal toxic units in the Yilong Lake decreased following the order Pb > Cr > As > Ni > Zn > Cd > Cu, with higher contributions to the sum of toxic units of Pb, Cr and As. 相似文献
894.
对吉林省西部农牧交错区典型生境土壤线虫群落进行调查,共捕获线虫23属、1 264只,优势属为真滑刃属和短体属。研究结果显示,土地利用方式对土壤线虫群落特征有一定影响,不同生境间土壤线虫群落共有属不多,农业生产活动促使土壤线虫向土壤下层移动;不同农业生产活动对土壤线虫群落多样性影响不同, 4种生境中,居民点园地土壤线虫群落多样性最高,而玉米田最低;不同土地利用方式下土壤线虫功能类群差异显著,玉米田不利于捕食类群/杂食类群的存在。 相似文献
895.
896.
Assessment of heavy metal pollution in wetland soils from the young and old reclaimed regions in the Pearl River Estuary, South China 总被引:16,自引:0,他引:16
Bai J Xiao R Cui B Zhang K Wang Q Liu X Gao H Huang L 《Environmental pollution (Barking, Essex : 1987)》2011,159(3):817-824
Soils were sampled in three types of wetlands from the young (A) and old (B) reclaimed regions of the Pearl River Estuary. They were analyzed for total concentrations of heavy metals to investigate their distributions and pollution levels in both regions. Results showed that most heavy metals in ditch and riparian wetlands did not significantly differ from those in reclaimed wetlands in A region, while significantly lower for Cd, Cu, Pb, and Zn in reclaimed wetlands in B region, suggesting higher effects of long-term reclamation. Iron, Cr and Cu were identified as metal pollutants of primary concern and had higher contributions to the total toxic units compared to other metals. Almost all metals exceeded their lowest effect levels and Fe and Cr even exceeded the severe effect levels. Multivariate analysis shows that Fe and Mn are controlled by parent rocks and other metals mainly originate from anthropogenic source. 相似文献
897.
898.
催化湿式氧化吡虫啉农药废水催化剂的研究 总被引:1,自引:0,他引:1
通过共沉淀法制备了用于湿式氧化吡虫啉农药废水的Cu/Mn复合氧化物催化剂,研究了沉淀剂种类、沉淀温度、焙烧温度和活性组分配比等因素等对Cu/Mn复合氧化物催化剂的活性及稳定性的影响,确定了最佳制备条件,利用BET比表面积测定和XRD对催化剂进行了表征.结果表明,优化条件制备的Cu/Mn复合氧化物催化剂催化湿式氧化处理吡虫啉农药废水时,具有较高的催化活性和稳定性.催化剂用量4 g/L,反应温度190℃,氧分压1.6 MPa,反应120 min,COD去除率为92.3%,活性组分溶出量较小. 相似文献
899.
Zhu Xiuhua Bai Hao Gao Yuan Chen Jiping Yuan Heping Wang Longxing Wang Wei Dong Xuewei Li Xiaoxiao 《Environmental science and pollution research international》2017,24(26):21203-21212
Environmental Science and Pollution Research - The concentrations of short-chain polychlorinated paraffins (SCCPs) in the urban air of Dalian, China, were monitored from March to October 2010 and... 相似文献
900.
白旭 《防灾减灾工程学报》2019,(4):67-70
从液压油污染、液压油油温升高、液压元件选择不合理、液压系统设计存在缺陷等几方面分析了斗轮堆取料机(以下简称斗轮机)液压系统长期存在的问题。根据液压系统的特点,确定了液压系统的改造设计;根据液压系统各种基本控制回路,确定了采用Spider 2全功能控制器对液压系统的控制方案和斗轮机液压系统的元件选型,并增加了液压油的温度控制功能。解决了斗轮机液压系统长期存在的缺陷和安全运行隐患,极大提高了生产效率和经济效益。 相似文献