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391.
以3-巯基丙酸(3-MPA)为修饰剂合成了水溶性CdSe量子点,优化了合成条件,并以其为荧光探针建立了水样中Pb2+和Hg2+的检测方法。实验结果表明:在n(Se)∶n(Cd2+)为1∶6、n(Se)∶n(NaBH4)为1∶3、n(Cd2+)∶n(3-MPA)为1∶6、反应pH为11、回流温度为100 ℃、回流时间为60 min的优化条件下合成的量子点荧光性能较优;量子点的荧光猝灭强度与Pb2+或Hg2+的质量浓度呈良好的线性关系,线性范围分别为0.005~10 mg/L和0.001~1 mg/L,检出限分别为0.003 mg/L和0.001 mg/L,相对标准偏差分别为1.23%和1.29%,可应用于实际水样中Pb2+和Hg2+的检测。 相似文献
392.
Forest Dynamics in the Eastern Ghats of Tamil Nadu,India 总被引:1,自引:0,他引:1
The primary deciduous forests in the Eastern Ghats (EG) of Tamil Nadu (TN) India have undergone many changes owing to various
need-based forest managements, such as timber extraction for industry, railway sleepers, charcoal, and forest clearance for
hydroelectric projects and agriculture, during preindependence and postindependence periods (i.e., from 1800 to 1980). The
enactment of a forest conservation act during the 1980s changed the perception of forest managers from utilization to conservation.
This study was taken up to assess the forests dynamics in the EG of TN spatially between 1990 and 2003 and nonspatially between
1900 and the 1980s. Landsat Thematic Mapper (TM) and Indian Remote Sensing satellite (IRS) 1D Linear Imaging and Self Scanning
(LISS III) data were used to assess forests during 1990 and 2003, respectively. Field floristic survey and secondary data
(such as published literature, floras, books, and forest working plans) were used to assess the forest dynamics in terms of
forest type and species composition among the preindependence period, the postindependence period, and the present (i.e.,
before and after 1980). The satellite data analysis revealed a considerable amount of changes in all forest types during the
13 years. The comparison of species composition and forest types between the past and present revealed that need-based forest
management along with anthropogenic activity have altered the primary deciduous forest in to secondary and postextraction
secondary forests such as southern thorn and southern thorn scrub forests in the middle [400–900 m above mean sea level (MSL)]
and lower slopes (<400 m MSL). However, the evergreen forests present at the upper slope (>900 m MSL) and plateau seemed not
to be much affected by the forest management. The changes estimated by the satellite data processing in the major forest types
such as evergreen, deciduous, southern thorn, and southern thorn scrub are really alarming because these changes have occurred
after the implementation of a forest conservation act. The dependence of local people on forests for various purposes in this
region is also considerably high, which might be a key factor for the changes in the forests. The results of this study not
only provide an outlook on the present status of the forests and the change trends but also provide the basis for further
studies on forests in the EG of TN. 相似文献
393.
394.
本研究使用MODIS红外辐射遥感数据在分析了异常热点光谱辐射特性的基础上,提出一个新的火情监测模型NDTI火点指数,并通过几起较大森林火灾对该模型进行了分析和验证,给出了该监测模型的详细算法.这种双通道比值指数和NDVI一样具有衰减仪器噪声和抵消常规大气影响的优点.研究表明,4 μm火点辐射通道和11 μm背景分量通道的组合突出了火点信息,选择合适的NDTI门限,NDTI指数能够准确检测火点,识别率可达到93%.根据对实时接收轨道的有限实测,由于使用极少的数据集数学运算操作,NDTI模型比MODIS推荐火情算法在计算速度上快两倍以上.EOS MODIS探测器具有多光谱和高光谱以及对热点监测动态范围宽的特点,MODIS的下一代多光谱探测器NPOESS NPP VIIRS同样继承了MODIS的优势,为NDTI算法模型提供了广阔的应用前景. 相似文献
395.
HAN Hai-yan HUANG Guo-dong JIN Shun-ping ZHENG Pei-chao XU Guo-hu LI Jian-quan WANG Hong-mei CHU Yan-nan 《环境科学学报(英文版)》2007,19(6):751-755
Ion mobility spectrometry (IMS) is a very fast, highly sensitive, and inexpensive technique, it permits efficient monitoring of volatile organic compounds like alcohols. In this article, positive ion mobility spectra for six alcohol organic compounds have been systematically studied for the first time using a high-resolution IMS apparatus equipped with a discharge ionization source. Utilizing protonated water cluster ions (H2O)nH^+ as the reactant ions and clean air as the drift gas, alcohol organic compounds, ethanol, 1- propanol, 2-propanol, 1-butanol, 1-pentanol and 2-octanol, all exhibit product ion characteristic peaks in their respective ion mobility spectrometry, that is a result of proton transfer reactions between the alcohols and reaction ions (H2O)nH^+. The mixture of these alcohols, including two isomers, has been detected, and the results showed that they could be distinguished effectively in the ion mobility spectrum. The reduced mobility values have been determined, which are in very well agreement with the traditional ^63Ni-IMS experimental values. The exponential dilution method was used to calibrate the alcohol concentrations, and a detection limit available for the alcohols is in order of magnitude of a few ng/L. 相似文献
396.
油田硫酸盐还原菌快速定量检测方法 总被引:2,自引:1,他引:1
现有油田废水中硫酸盐还原菌检测周期长、检测费用较高,本研究应用聚合酶链式反应(PCR)技术与倍比稀释法(MPN)相结合的DSR-MPN-PCR法,对硫酸盐还原菌进行快速定量检测.从废水中制备了直接用于PCR扩增的菌液,保证了定量准确性;建立以硫酸盐还原菌亚硫酸盐还原酶基因(Dsr)为靶位点的通用探针DSR1F和DSR5R的反应体系和扩增条件.结果表明,该方法检测灵敏度明显比液体稀释培养法高2个数量级,真实地表征了废水中实际的SRB菌数量,整个操作过程需要3~4 h,检测结果非常稳定,降低了检测费用,可以在生产中应用. 相似文献
397.
针对传统森林火灾检测手段响应速度慢、效率低、误报率高等问题,设计了无人机搭载的由云台和相机组成的图像采集平台,通过火灾智能识别技术,实时识别监测火灾的发生,并达到了自动抵近侦察及实时态势感知的效果。在火灾智能识别算法方面,提出了improved-YOLOv3算法,通过在特征交互阶段增加yolo层,加强了网络对特征的融合度,从而增加了网络的检测能力。通过与性能相似的网络进行对比测试,验证了改进算法的有效性。测试结果表明,提出的算法检测准确率高、漏检率低、推理速度快,能够适用于实际火灾现场监测。 相似文献
398.
399.
本文介绍了基于LabVIEW虚拟仪器的机械式振动试验台检测系统的构成,工作流程和LabVIEW在其中的应用,以此展示虚拟仪器技术使得现代检测系统变得更加简单、方便、有效。 相似文献
400.
便携式渗漏检测装置在填埋场防渗层完整性检测的应用 总被引:3,自引:1,他引:2
利用基于双电极法的偶极子检测和基于电极栅格法的区块化检测装置,对重庆某生活垃圾填埋场进行了防渗层高密度聚乙烯(HDPE)膜完整性检测.结果表明:偶极子在漏洞附近时,其周围电势分布会出现正负突变;区块化检测利用网格铺设电极和上位机软件解析可以精确定位漏洞位置.基于高压直流电法的便携式渗漏检测系统,在填埋场铺设防护层的条件下能够有效地检测到直径约1 cm的漏洞,并且能够对漏洞进行精确定位.对 2种不同电学方法的验证表明,电极栅格法比双电极法测量范围大、精度高. 相似文献