全文获取类型
收费全文 | 2524篇 |
免费 | 156篇 |
国内免费 | 952篇 |
专业分类
安全科学 | 234篇 |
废物处理 | 139篇 |
环保管理 | 194篇 |
综合类 | 1557篇 |
基础理论 | 448篇 |
污染及防治 | 706篇 |
评价与监测 | 131篇 |
社会与环境 | 131篇 |
灾害及防治 | 92篇 |
出版年
2024年 | 10篇 |
2023年 | 72篇 |
2022年 | 142篇 |
2021年 | 150篇 |
2020年 | 125篇 |
2019年 | 106篇 |
2018年 | 124篇 |
2017年 | 139篇 |
2016年 | 102篇 |
2015年 | 157篇 |
2014年 | 203篇 |
2013年 | 214篇 |
2012年 | 222篇 |
2011年 | 220篇 |
2010年 | 158篇 |
2009年 | 161篇 |
2008年 | 192篇 |
2007年 | 139篇 |
2006年 | 147篇 |
2005年 | 86篇 |
2004年 | 60篇 |
2003年 | 86篇 |
2002年 | 89篇 |
2001年 | 86篇 |
2000年 | 63篇 |
1999年 | 56篇 |
1998年 | 51篇 |
1997年 | 43篇 |
1996年 | 51篇 |
1995年 | 36篇 |
1994年 | 39篇 |
1993年 | 21篇 |
1992年 | 20篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有3632条查询结果,搜索用时 15 毫秒
971.
972.
江苏南京地区蜻蜓目(Odonata)昆虫区系及多样性分析 总被引:2,自引:0,他引:2
2005~2008年对江苏南京地区的蜻蜓资源进行了调查,共发现蜻蜓目昆虫45种,隶属于8科29属。其区系组成的特点是:东洋成分占明显优势,有13种,约占总数的2889%;古北区的种类相对较少,只有5种,约占总数的1111%。研究分析了7个样地蜻蜓的物种丰富度多样性指数(〖WTBX〗H′)、均匀度指数(J)、优势度指数(D)和相似性系数(Cs〖WTBZ〗)。结果发现:蜻蜓物种丰富度由大到小的顺序为紫金山(30)=老山(30)>将军山(24)>江心洲(19)>方山(18)>东庐山(13)>金牛湖(9);各样地的多样性指数排序为将军山(2.9298)>紫金山(2.9150)>老山(2.7258)>方山(2.6574)>江心洲(2.5478)>东庐山(1.9025)>金牛湖(1.6700)。其中,方山与东庐山的相似性系数最大(0.7742),金牛湖分别与紫金山和老山的相似性系数最小(0.4103)。 相似文献
973.
Xiao-Huan Liu Yang Zhang Shu-Hui Cheng Jia Xing Qiang Zhang David G. Streets Carey Jang Wen-Xing Wang Ji-Ming Hao 《Atmospheric environment (Oxford, England : 1994)》2010,44(20):2415-2426
The U.S. EPA Models-3 Community Multiscale Air Quality (CMAQ) modeling system with the process analysis tool is applied to China to study the seasonal variations and formation mechanisms of major air pollutants. Simulations show distinct seasonal variations, with higher surface concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM10), column mass of carbon monoxide (CO) and NO2, and aerosol optical depth (AOD) in winter and fall than other seasons, and higher 1-h O3 and troposphere ozone residual (TOR) in spring and summer than other seasons. Higher concentrations of most species occur over the eastern China, where the air pollutant emissions are the highest in China. Compared with surface observations, the simulated SO2, NO2, and PM10 concentrations are underpredicted throughout the year with NMBs of up to ?51.8%, ?32.0%, and ?54.2%, respectively. Such large discrepancies can be attributed to the uncertainties in emissions, simulated meteorology, and deviation of observations based on air pollution index. Max. 1-h O3 concentrations in Jan. and Jul. at 36-km are overpredicted with NMBs of 12.0% and 19.3% and agree well in Apr. and Oct. Simulated column variables can capture the high concentrations over the eastern China and low values in the central and western China. Underpredictions occur over the northeastern China for column CO in Apr., TOR in Jul., and AODs in both Apr. and Jul.; and overpredictions occur over the eastern China for column CO in Oct., NO2 in Jan. and Oct., and AODs in Jan. and Oct. The simulations at 12-km show a finer structure in simulated concentrations than that at 36-km over higher polluted areas, but do not always give better performance than 36-km. Surface concentrations are more sensitive to grid resolution than column variables except for column NO2, with higher sensitivity over mountain and coastal areas than other regions. 相似文献
974.
Miao-Ching Cheng Chen-Feng You Fei-Jan Lin Chuan-Hsiung Chung Kuo-Fang Huang 《Atmospheric environment (Oxford, England : 1994)》2010,44(28):3386-3393
We investigated chemical and Sr isotopic composition of monthly rainwater collected on Peng-Chia-Yu (PCY) in northern Taiwan. Rainwater 87Sr/86Sr ratios, Na/Cl, Ca/Cl, Sr/Cl, Sr/Ca, NH4/Cl, NO3/Cl, SO4/Cl and Na/Sr, showed clear seasonal cycles, reflecting mixture of loess carbonates (high Ca/Sr and more radiogenic 87Sr/86Sr) and seawater (low Ca/Sr and intermediate 87Sr/86Sr). Model results showed that the former source contributes up to 45% during the winter monsoon period, but seawater is the dominant Sr source in rainwater (>50%) at other times. Two anomalously low 87Sr/86Sr values occurred in July and August 1998, coinciding with the Merapi eruption in Indonesia. Air-mass backward trajectories and the geochemical and isotopic compositions in rainwater and Merapi lava (i.e. Ca/Sr = 100 and 87Sr/86Sr = 0.705400) suggested that the Merapi eruption delivered ash across the western equatorial Pacific to PCY. Aerosols leaching experiments were conducted to examine the impact of the 1998 eruption, demonstrating that only a minor terrestrial signature can be extracted by distilled water, implying rapid dispatch of volcanic gases or high-efficiency dissolution of ash related substance in acidic rains. 相似文献
975.
976.
Xun Chen Yumei Zhang Lingyan Cheng Huaping Wang 《Journal of Polymers and the Environment》2009,17(4):273-279
Rheological behavior of the concentrated cellulose/1-butyl-3-methylimidazolium chloride ([BMIM]Cl) solutions was investigated.
As polymeric fluid, solutions of cellulose in [BMIM]Cl display a marked elastic behavior under shear flow. The dependence
of the shear viscosity η, and of the dynamic modulus, on concentration, average degree of polymerization (DP) and temperature
is discussed. At lower concentrations and degrees of polymerization (DP), cellulose solutions show viscous, inelastic behavior
at low frequencies and low shear rate. At higher concentration and DP, cellulose solutions are more elastic at higher frequencies
and shear rate. Such solutions also have some usual rheological properties. The dynamic rheological responses revealed that
the Cox–Merz rule did not hold for these cellulose solutions at high deformation rate. Plotting storage modulus G′ against
loss modulus G″ gave almost a master curve which is independent of temperature and concentration, with the slope of about
1.651 for 10 wt% cellulose solutions. This value indicates the existence of microheterogeneity in the solution system. 相似文献
977.
改性蒙脱石-壳聚糖絮凝剂处理造纸废水 总被引:2,自引:0,他引:2
将改性蒙脱石(MM)和壳聚糖(CTS)制成MM-CTS新型复合絮凝剂,对造纸废水进行絮凝处理.实验结果表明,当MM-CTS的加入量为0.10 mg/L、m(MM):m(CTS):40:1、pH=8.0、搅拌速率为140 r/min、沉降时间为15 min时,絮凝效果最佳,对造纸废水的COD去除率达66.35%,较传统絮凝剂的COD去除率提高了13.7%,药剂成本下降11.1%,具有明显的经济与环境效益. 相似文献
978.
979.
本文介绍了全氟异丁烯(PFIB)物化性质及产生;总结了其毒性;分析了气相色谱法分析PFIB方法:讨论了人员和环境防护技术. 相似文献
980.
以有机硅高沸物和Na2SiO3·9H2O为原料,采用溶胶-凝胶法制备出疏水性的类氧化硅气凝胶吸附材料。采用透射电子显微镜、傅里叶变换红外分析仪和比表面与空隙度分析仪对该吸附材料的结构进行表征。表征结果显示,该吸附材料呈海绵状多孔结构,比表面积为294.48 m2/g,孔径分布较宽(为2 ~140 nm),平均孔径为8.95 nm。实验结果表明:采用该吸附材料常温下静态吸附处理质量浓度为10 mg/L的罗丹明B(RhB)溶液,在类氧化硅气凝胶吸附材料加入量50 g/L、静态吸附时间5 h的最佳静态吸附工艺条件下,RhB去除率为98.8%,吸附后RhB质量浓度为0.124 mg/L;采用该吸附材料常温下动态吸附处理质量浓度为15 mg/L的RhB溶液,吸附4 h后开始穿透,吸附7 h后完全穿透。穿透时间较长,表明该吸附材料具有较大的吸附容量。 相似文献