全文获取类型
收费全文 | 20195篇 |
免费 | 1684篇 |
国内免费 | 4125篇 |
专业分类
安全科学 | 2870篇 |
废物处理 | 334篇 |
环保管理 | 3142篇 |
综合类 | 12700篇 |
基础理论 | 2057篇 |
环境理论 | 9篇 |
污染及防治 | 1236篇 |
评价与监测 | 1101篇 |
社会与环境 | 1536篇 |
灾害及防治 | 1019篇 |
出版年
2024年 | 93篇 |
2023年 | 410篇 |
2022年 | 783篇 |
2021年 | 1000篇 |
2020年 | 977篇 |
2019年 | 761篇 |
2018年 | 667篇 |
2017年 | 851篇 |
2016年 | 943篇 |
2015年 | 992篇 |
2014年 | 1025篇 |
2013年 | 1224篇 |
2012年 | 1497篇 |
2011年 | 1539篇 |
2010年 | 1091篇 |
2009年 | 1140篇 |
2008年 | 843篇 |
2007年 | 1319篇 |
2006年 | 1288篇 |
2005年 | 1151篇 |
2004年 | 981篇 |
2003年 | 919篇 |
2002年 | 791篇 |
2001年 | 677篇 |
2000年 | 606篇 |
1999年 | 556篇 |
1998年 | 382篇 |
1997年 | 319篇 |
1996年 | 213篇 |
1995年 | 201篇 |
1994年 | 172篇 |
1993年 | 155篇 |
1992年 | 97篇 |
1991年 | 58篇 |
1990年 | 43篇 |
1989年 | 22篇 |
1988年 | 30篇 |
1987年 | 20篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1983年 | 16篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 6篇 |
1973年 | 8篇 |
1972年 | 8篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
烟尘测试中测孔位置和测点的合理布置 总被引:2,自引:0,他引:2
根据作者长期在监测第一线的实践经验及在烟尘采样中所遇到的一些具体问题,着重提出了诸多不规则烟道的烟尘采样方法及注意事项,既有理论依据,可操作性也强。 相似文献
143.
乌鲁木齐市汽车尾气排污现状及防治对策探讨 总被引:1,自引:0,他引:1
对乌鲁木齐市在用车辆进行了路抽检调查,通过大量数据分析,得出乌鲁木齐市目前汽车尾气排放情况仍令人担忧,治理工作不容忽视。 相似文献
144.
145.
介绍了广东省地方污染物排放标准中的《水污染物排放限值》和《大气污染物排放限值》的主要特点 ,对今后标准修订提出了建议 相似文献
146.
A ten year summary of concurrent ambient water column and sediment toxicity tests in the Chesapeake Bay watershed: 1990-1999 总被引:1,自引:0,他引:1
The goal of this study was to identify the relative toxicity ofambient areas in the Chesapeake Bay watershed by using a suiteof concurrent water column and sediment toxicity tests at seventy-five ambient stations in 20 Chesapeake Bay rivers from1990 through 1999. Spatial and temporal variability was examinedat selected locations throughout the 10 yr study. Inorganicand organic contaminants were evaluated in ambient water andsediment concurrently with water column and sediment tests toassess possible causes of toxicity although absolute causalitycan not be established. Multivariate statistical analysis wasused to develop a multiple endpoint toxicity index (TOX-INDEX) at each station for both water column and sediment toxicity data. Water column tests from the 10 yr testing period showed that49% of the time, some degree of toxicity was reported. The mosttoxic sites based on water column results were located inurbanized areas such as the Anacostia River, Elizabeth River andthe Middle River. Water quality criteria for copper, lead,mercury, nickel and zinc were exceeded at one or more of thesesites. Water column toxicity was also reported in localizedareas of the South and Chester Rivers. Both spatial and temporalvariability was reported from the suite of water column toxicitytests. Some degree of sediment toxicity was reported from 62% of the tests conducted during the ten year period. The ElizabethRiver and Baltimore Harbor stations were reported as the most toxic areas based on sediment results.Sediment toxicity guidelines were exceeded for one or more of thefollowing metals at these two locations: arsenic, cadmium,chromium, copper, lead, nickel and zinc. At the Elizabeth Riverstations nine of sixteen semi-volatile organics and two of sevenpesticides measured exceeded the ER-M values in 1990. Ambientsediment toxicity tests in the Elizabeth River in 1996 showedreduced toxicity. Various semi-volatile organics exceeded the ER-M values at a number of Baltimore Harbor sites; pyrene anddibenzo(a,h)anthracene were particularly high at one of thestations (Northwest Harbor). Localized sediment toxicity was alsoreported in the Chester, James, Magothy, Rappahannock, andPotomac Rivers but the link with contaminants was not determined.Both spatial and temporal variability was less for sedimenttoxicity data when compared with water column toxicity data. Acomparison of water column and sediment toxicity data for thevarious stations over the 10 yr study showed that approximatelyhalf the time agreement occurred (either both suite of testsshowed toxicity or neither suite of tests showed toxicity). 相似文献
147.
Lake V?nern, the largest lake in Sweden, has been seriously contaminated with mercury during the 20th century. In the 1970's and 80's the direct load, mainly from a chlor-alkali industry in the area, of mercury was drastically reduced as a response to new legislation, from three to five tons down to between five and ten kg yr(-1). Large amounts of the disposed pollutant have accumulated in the sediments. The question posed in this work is now, is the effect of the drastic load reduction after more than two decades visible in the sediments? The question is relevant as large areas still are blacklisted for fishing, but also as a follow-up of a major remedy action. The lake also serves as a freshwater reservoir for even Sweden's second largest city. This work synthesises and compares data of mercury in the sediments from three major field programs, in 1974, 1984 and 1998. The interest is focused on both spatial heterogeneity and temporal trends. In 1974, the surface concentrations are significantly higher than in subsequent surveys. Significant differences are also found between 1984 and 1998. Significant spatial differences within the lake are found for respective year. The most contaminated area is located in the north, close to the major point source (a former chlor-alkali industry). This is also the area with the largest improvement, as a direct response to the reduction in load. Further from the outlet, the recovery is more affected by burial and transport processes out into the deeper basins. 相似文献
148.
149.
气相和颗粒物中邻苯二甲酸酯的采样与检测技术 总被引:2,自引:0,他引:2
对邻苯二甲酸酯的性质及其在环境空气中的存在状态、样品采集技术与分析方法进行了综述,侧重介绍了样品的采集、净化、采样效率和采样与分析全过程的质量控制。 相似文献
150.
The article describes the use of Scots pine bark to identifynitrogen sources in eastern Germany, as well as background areas in Russia and Bulgaria, by using natural isotope ratios of total nitrogen (Nt) and individual N compoundssuch as ammonium (NH4
+), nitrate (NO3
-)and amid nitrogen (amide-N). The samples collected were analysed using an elemental analyser in connection with a gas isotope mass spectrometer (EA-IRMS). Natural 15N abundances in pine bark from impact areas suggest that the ammonium accumulated on the surface of the bark is releasedfrom livestock management. Bark of Scots pines growing near agricultural land had highly depleted 15Nt values (between –8 and –12), while bark from background areas (unpolluted areas) displayed slightly negative 15Nt values (mean 15Nt = –3.8). It is assumed that part of the N adsorbed on the bark surface is mainly derived from ammonia(mean 15Nt = –40.3) escaping from livestock housing and during the application of manure. This assumption is confirmed by experiments under controlled conditions in which manure samples were spread on soil. In addition, temporal and spatial variations of 15Nt abundances in pine bark from various locations in eastern Germany as wellas pine stands in Nature Park Dübener Heath are discussed. 相似文献