全文获取类型
收费全文 | 9418篇 |
免费 | 774篇 |
国内免费 | 2376篇 |
专业分类
安全科学 | 371篇 |
废物处理 | 163篇 |
环保管理 | 1997篇 |
综合类 | 6699篇 |
基础理论 | 1105篇 |
环境理论 | 6篇 |
污染及防治 | 711篇 |
评价与监测 | 1074篇 |
社会与环境 | 395篇 |
灾害及防治 | 47篇 |
出版年
2024年 | 53篇 |
2023年 | 208篇 |
2022年 | 295篇 |
2021年 | 378篇 |
2020年 | 393篇 |
2019年 | 340篇 |
2018年 | 275篇 |
2017年 | 365篇 |
2016年 | 378篇 |
2015年 | 466篇 |
2014年 | 485篇 |
2013年 | 655篇 |
2012年 | 629篇 |
2011年 | 691篇 |
2010年 | 564篇 |
2009年 | 544篇 |
2008年 | 467篇 |
2007年 | 630篇 |
2006年 | 646篇 |
2005年 | 475篇 |
2004年 | 431篇 |
2003年 | 478篇 |
2002年 | 405篇 |
2001年 | 367篇 |
2000年 | 350篇 |
1999年 | 260篇 |
1998年 | 199篇 |
1997年 | 176篇 |
1996年 | 155篇 |
1995年 | 117篇 |
1994年 | 115篇 |
1993年 | 81篇 |
1992年 | 76篇 |
1991年 | 63篇 |
1990年 | 44篇 |
1989年 | 27篇 |
1988年 | 24篇 |
1987年 | 38篇 |
1986年 | 19篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1982年 | 18篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 20篇 |
1978年 | 22篇 |
1977年 | 10篇 |
1973年 | 10篇 |
1972年 | 12篇 |
1971年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
581.
Marcos A. dos Santos Cynthia F. Illanes Adalgiza Fornaro Jairo J. Pedrotti 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):85-92
During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown São Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, $ \rm NH^{ + }_{4} During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown
S?o Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as
well as major ions (Na+, , K+, Ca2+, Mg2+, Cl−, , ) and carboxylic acids (acetic, formic and oxalic) using ion chromatography. The volume weighted mean, VWM, of the anions
, and Cl− was, respectively, 20.3, 12.1 and 10.7 μmol l−1. Rainwater in S?o Paulo was acidic, with 55% of the samples exhibiting a pH below 5.6. The VWM of the free H+ was 6.27 μmol l−1), corresponding to a pH of 5.20. Ammonia (NH3), determined as (VWM = 32.8 μmol l−1), was the main acidity neutralizing agent. Considering that the H+ ion is the only counter ion produced from the non-sea-salt fraction of the dissociated anions, the contribution of each anion
to the free acidity potential has the following profile: (31.1%), (26.0%), CH3COO− (22.0%), Cl− (13.7%), HCOO− (5.4%) and (1.8%). The precipitation chemistry showed seasonal differences, with higher concentrations of ammonium and calcium during
autumn and winter (dry period). The marine contribution was not significant, while the direct vehicular emission showed to
be relevant in the ionic composition of precipitation. 相似文献
582.
Naszradi T Badacsonyi A Keresztényi I Podar D Csintalan Z Tuba Z 《Environmental monitoring and assessment》2007,134(1-3):279-285
Moss transplants of Tortula ruralis were used as active biomonitoring organisms as part of a monitoring study to assess the metals (Al, Cd, Cu, Cr, Fe, Ni, Pb, V and Zn) associated with ambient particles on mosses in Budapest, the capital town of Hungary. The moss samples were collected in a nature conservation area from a semi-arid sand grassland (Festucetum vaginatae danubiale), less than 1 month before transplantation. Moss cushions were exposed to pollution in Budapest during October–November 1993 and February–March 1994. In the study area, 16 sites were marked out as measuring sites, in accordance with the structure of the city. A similar stand was established in the Botanical Gardens of the Szent István University in Gödöll? as a control site. ICP-AES analysis of moss for metals showed the ability of Tortula ruralis to accumulate the metals under study. Control site showed lower impact in comparison to the other sites. 相似文献
583.
Lemly AD 《Environmental monitoring and assessment》2007,125(1-3):361-375
This paper gives step-by-step instructions for assessing aquatic selenium hazards associated with mining. The procedure was
developed to provide the U.S. Forest Service with a proactive capability for determining the risk of selenium pollution when
it reviews mine permit applications in accordance with the National Environmental Policy Act (NEPA). The procedural framework
is constructed in a decision-tree format in order to guide users through the various steps, provide a logical sequence for
completing individual tasks, and identify key decision points. There are five major components designed to gather information
on operational parameters of the proposed mine as well as key aspects of the physical, chemical, and biological environment
surrounding it — geological assessment, mine operation assessment, hydrological assessment, biological assessment, and hazard
assessment. Validation tests conducted at three mines where selenium pollution has occurred confirmed that the procedure will
accurately predict ecological risks. In each case, it correctly identified and quantified selenium hazard, and indicated the
steps needed to reduce this hazard to an acceptable level. By utilizing the procedure, NEPA workers can be confident in their
ability to understand the risk of aquatic selenium pollution and take appropriate action. Although the procedure was developed
for the Forest Service it should also be useful to other federal land management agencies that conduct NEPA assessments, as
well as regulatory agencies responsible for issuing coal mining permits under the authority of the Surface Mining Control
and Reclamation Act (SMCRA) and associated Section 401 water quality certification under the Clean Water Act. Mining companies
will also benefit from the application of this procedure because priority selenium sources can be identified in relation to
specific mine operating parameters. The procedure will reveal the point(s) at which there is a need to modify operating conditions
to meet environmental quality goals. By recognizing concerns early in the NEPA process, it may be possible for a mining company
to match operational parameters with environmental requirements, thereby increasing the likelihood that the permit application
will be approved. 相似文献
584.
A biennial integrated survey, based on the use of vascular plants for the bioindication of the effects of tropospheric ozone together with the use of automatic analysers of ozone, as well as the mapping of lichen biodiversity was performed in the area of Castelfiorentino (Tuscany, central Italy). Photochemically produced ozone proved to be a fundamental presence during the warm season, with maximum hourly means reaching 114 ppb, exceeding the information threshold as fixed by EU: the use of supersensitive tobacco Bel-W3 confirmed the opportunity of carrying out detailed cost-effective monitoring surveys. The potential for didactical and educational implications of this methodology are appealing. Critical levels set up for the protection of vegetation have exceeded considerably. The comparison of biomass productivity in sensitive and resistant individuals (NC-S and NC-R white clover clones, in the framework of an European network) provided evidence that ambient ozone levels are associated with relevant reduction (up to 30%) in the performance of sensitive material; effects on flowering were also pronounced. The economic assessment of such an impact deserves attention. Mapping of epiphytic lichen biodiversity – which has been used to monitor air quality worldwide – was not related to ozone geographical distribution as depicted by tobacco response. 相似文献
585.
An air quality sampling program was designed and implemented to collect the baseline concentrations of respirable suspended
particulates (RSP = PM10), non-respirable suspended particulates (NRSP) and fine suspended particulates (FSP = PM2.5). Over a three-week period, a 24-h average concentrations were calculated from the samples collected at an industrial site
in Southern Delhi and compared to datasets collected in Satna by Envirotech Limited, Okhla, Delhi in order to establish the
characteristic difference in emission patterns. PM2.5, PM10, and total suspended particulates (TSP) concentrations at Satna were 20.5 ± 6.0, 102.1 ± 41.1, and 387.6 ± 222.4 μg m−3 and at Delhi were 126.7 ± 28.6, 268.6 ± 39.1, and 687.7 ± 117.4 μg m−3. Values at Delhi were well above the standard limit for 24-h PM2.5 United States National Ambient Air Quality Standards (USNAAQS; 65 μg m−3), while values at Satna were under the standard limit. Results were compared with various worldwide studies. These comparisons
suggest an immediate need for the promulgation of new PM2.5 standards. The position of PM10 in Delhi is drastic and needs an immediate attention. PM10 levels at Delhi were also well above the standard limit for 24-h PM10 National Ambient Air Quality Standards (NAAQS; 150 μg m−3), while levels at Satna remained under the standard limit. PM2.5/PM10 values were also calculated to determine PM2.5 contribution. At Satna, PM2.5 contribution to PM10 was only 20% compared to 47% in Delhi. TSP values at Delhi were well above, while TSP values at Satna were under, the standard
limit for 24-h TSP NAAQS (500 μg m−3). At Satna, the PM10 contribution to TSP was only 26% compared to 39% in Delhi. The correlation between PM10, PM2.5, and TSP were also calculated in order to gain an insight to their sources. Both in Satna and in Delhi, none of the sources
was dominant a varied pattern of emissions was obtained, showing the presence of heterogeneous emission density and that nonrespirable
suspended particulate (NRSP) formed the greatest part of the particulate load. 相似文献
586.
Singh S Sharma DK Dhar S Kumar A Kumar A 《Environmental monitoring and assessment》2007,130(1-3):301-309
Two measurement campaigns were conducted in two sampling sites, An Thinh and Duy Minh, in northern Vietnam during the months
of November–December 2000 and November 2001–February 2002 in order to investigate the extend of the particulate air pollution
from the Pha Lai coal fired power plant. Fine particle samples were analyzed by Energy Dispersive X-Ray Fluorescence spectrometry
and soot samples were analyzed by reflectometer. The result showed that high concentration of soot and elements mostly coincided
with the air masses originating from the power plant. Sea spray aerosol was found to be the major source of chlorine at both
sites. Ratios of specific elements and principal component analysis (PCA) revealed that coal combustion was the main contributor
to the air pollution at both sites. PCA also indicated that there were other sources responsible for the elements emission,
probably the influence of long distance transport and Asian Brown Cloud. 相似文献
587.
Cadmium pollution resulted from fertilizer applications were studied by determining cadmium levels in agricultural and non-agricultural soils of Bafra and Çar?amba plains. Soil samples of 68 were collected from agricultural (34) and non-agricultural (34) areas. The sample of 2 g was placed in a test tube and digested with hydrochloric acid and nitric acid mixture (3:1, v/v) in an aluminum block. Taking up the evaporated residue was dissolved in 1% nitric acid and total cadmium concentrations were determined with GF-AAS. Mean level of cadmium contents were found in agricultural areas 0.162?±?0.078 for Çar?amba and 0.433?±?0.288 mg kg?1 for Bafra. The accuracy of the method was tested with determining cadmium contents of standard reference material and cadmium spiked soil samples. 相似文献
588.
Demirel Z 《Environmental monitoring and assessment》2007,132(1-3):15-23
In this study, heavy metal contents of groundwater from the Mersin aquifer were determined with photometric methods and used
to determine the main factors controlling the pollution of groundwater in the area. Using MapInfo GIS software, spatial analysis
and integration were carried out for mapping drinking water quality in the basin. From the photometric heavy metal analysis,
it is inferred that the excess concentration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality
for drinking purposes. Similarly, the EC thematic map shows that considerable areas in the basin are having high salinity
hazards. The reason for excess concentration of various heavy metals is the industrial activities and petroleum pipelines
and salinity levels show the sea water intrusion. 相似文献
589.
Syed S 《Environmental monitoring and assessment》2007,130(1-3):311-322
‘Metal ash’ presents a waste disposal problem in most of the developing countries as the industries employ obsolete technologies.
In this paper we describe analysis of tin ash, zinc ash and aluminium ash by means of optical methods, such as X-ray diffraction
(XRD), inductively coupled plasma mass spectrometry (ICP-MS), electron probe micro analysis (EPMA), scanning electron microscopy
(SEM) and chemical methods. The results of tin ash obtained by XRD method matched well with the cassiterite, a naturally occurring
mineral of tin. ICP-MS studies reveal the presence of a large number of tracer metals, which may cause pollution by tertiary
dispersion and this aspect is discussed. Conversely, the data generated by chemical methods are limited. However, the methods
are simple and cost-effective. Then, they can easily be adopted by low-budget industries. Simple and cost-effective process
to recover tin from tin ash is described. It is based on heating tin ash with sodium cyanide to about 900°C to separate tin
component from the metal ash. The process recovers good quality tin and offers a very high yield. The process can be scaled
up to small pilot plant. 相似文献
590.
Jaji MO Bamgbose O Odukoya OO Arowolo TA 《Environmental monitoring and assessment》2007,133(1-3):473-482
The quality of Ogun river in South-West, Nigeria was studied by a field survey for a period of 1 year (covering dry season
and rainy season). Water samples were collected from thirteen sites and analysed for physico-chemical and bacteriological
parameters as well as heavy metals using standard methods. Generally, the values obtained for turbidity, phosphate, oil and
grease, iron and faecal coliform from all the sites in both seasons were above the maximum acceptable limit set by the World
Health Organization (WHO) for drinking water. Also, the manganese content from all the sites in the dry season, lead concentrations
from three sites in the dry season and cadmium concentrations from some sites in both seasons were above the WHO limit. The
values obtained for total dissolved solids, dissolved oxygen and chloride at site M in the dry season and nitrate at site
J in the rainy season were also above the WHO limit. Pollution of Ogun river water along its course is evidenced by the high
concentrations of pollution indicators, nutrients and trace metals above the acceptable limit. This poses a health risk to
several rural communities who rely on the river primarily as their source of domestic water. The study showed a need for continuous
pollution monitoring programme of surface waters in Nigeria. 相似文献