全文获取类型
收费全文 | 16033篇 |
免费 | 201篇 |
国内免费 | 136篇 |
专业分类
安全科学 | 454篇 |
废物处理 | 587篇 |
环保管理 | 2228篇 |
综合类 | 3105篇 |
基础理论 | 4009篇 |
环境理论 | 10篇 |
污染及防治 | 3934篇 |
评价与监测 | 973篇 |
社会与环境 | 944篇 |
灾害及防治 | 126篇 |
出版年
2022年 | 124篇 |
2021年 | 128篇 |
2020年 | 112篇 |
2019年 | 135篇 |
2018年 | 202篇 |
2017年 | 241篇 |
2016年 | 331篇 |
2015年 | 282篇 |
2014年 | 375篇 |
2013年 | 1343篇 |
2012年 | 480篇 |
2011年 | 638篇 |
2010年 | 511篇 |
2009年 | 572篇 |
2008年 | 638篇 |
2007年 | 664篇 |
2006年 | 629篇 |
2005年 | 506篇 |
2004年 | 491篇 |
2003年 | 503篇 |
2002年 | 438篇 |
2001年 | 544篇 |
2000年 | 425篇 |
1999年 | 244篇 |
1998年 | 203篇 |
1997年 | 194篇 |
1996年 | 210篇 |
1995年 | 217篇 |
1994年 | 209篇 |
1993年 | 206篇 |
1992年 | 218篇 |
1991年 | 203篇 |
1990年 | 204篇 |
1989年 | 176篇 |
1988年 | 153篇 |
1987年 | 132篇 |
1986年 | 157篇 |
1985年 | 158篇 |
1984年 | 160篇 |
1983年 | 162篇 |
1982年 | 163篇 |
1981年 | 164篇 |
1980年 | 152篇 |
1979年 | 145篇 |
1978年 | 108篇 |
1977年 | 121篇 |
1974年 | 109篇 |
1973年 | 91篇 |
1972年 | 109篇 |
1971年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
771.
McClenny WA Oliver KD Jacumin HH Daughtrey EH Whitaker DA 《Journal of environmental monitoring : JEM》2005,7(3):248-256
Diffusive sampling of a mixture of 42 volatile organic compounds (VOCs) in humidified, purified air onto the solid adsorbent Carbopack X was evaluated under controlled laboratory conditions. The evaluation included variations in sample air temperature, relative humidity and ozone concentration. Linearity of samples with loading was examined both for a constant concentration with time varied up to 24 h and for different concentrations over 24 h. Reverse diffusion and its increase with accumulation of sample were determined for all compounds. Tubes were examined for blank levels, change of blanks with storage time, and variability of blanks. Method detection limits were determined based on seven replicate samples. Based on this evaluation, 27 VOCs were selected for quantitative monitoring in the concentration range from approximately 0.1 to 4 ppbv. Comparison results of active and diffusive samples taken over 24 h and under the same simulated ambient conditions at a constant 2 ppbv were interpreted to estimate the effective diffusive sampling rates (ml min(-1)) and their uncertainties and to calculate the corresponding diffusive uptake rates (ng ppmv(-1) min(-1)). 相似文献
772.
Nie H Chettle DR Webber CE Brito JA O'Meara JM McNeill FE 《Journal of environmental monitoring : JEM》2005,7(11):1069-1073
Long term lead metabolism in the human body has never been fully understood due to the lack of human data in this area. The technological improvement of bone lead measurement systems has made bone lead data of substantial populations available. In this study, a set of X-ray fluorescence bone lead data was used to test Leggett's lead metabolism model (R. W. Leggett, Environ. Health Perspect., 1993a, 101, 598-616), especially the model of metabolism in bone. The data set includes the bone lead concentration of 539 occupationally exposed workers, of whom 327 were measured twice in five years. The bone lead concentrations of both cortical bone (tibia) and trabecular bone (calcaneus) were obtained by Cd-109 gamma-ray induced XRF measurement. The histories of blood lead concentration for these workers were used to regulate the input file of the model. The results show that the bone lead concentrations predicted by Leggett's model greatly underestimate the measured values, especially for older workers. This data set was then organized into five age groups. A new simplified model was applied to estimate the lead transfer rates between blood and lead compartments for these age groups. The original transfer rates and the new transfer rates are compared, and the differences are discussed. When the transfer rates derived from measured bone lead data were put into the input file of the model to replace the existing parameters, the predicted values were much closer to the measured values for both cortical bone and trabecular bone. 相似文献
773.
Distribution of actinomycetes in oil contaminated ultisols of the Niger Delta (Nigeria) 总被引:1,自引:0,他引:1
J.P.Essien 《环境科学学报》2000,12(3):296-302
The distribution of actinomycetes in oil contaminated sandy loam ultisols of the Niger Delta region of Nigeria was studied to aid in understanding the effect of hydrocarbons on indigenous microbial population in tropical soils. The average total counts of actinomycetes in all the oil samples analysed was 103 cfu/g. Higher counts of actinomycetes were observed during the dry season than during the wet season. The counts of hydrocarbonoclastic actinomycetes correlated positively with the total count of actinomycetes.The actinomycetes were generally restricted to the top soil(0-10 cm soil depth) although a seemingly deeper(down to 40 cm soil depth) distribution was noticed in the dry season. The isolates included oil degrading species of Actinoplanes, Norcadia,Streptomyces and Streptosporangium. Their high oil utilization ability indicates their positive potential and role in the bioremediation of oil-spilled soils. 相似文献
774.
This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males.
Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced
testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes.
Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of
predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous
compounds in the urine; however, the underlying mechanisms are not yet known.
Received: 31 January 2000 / Accepted in revised form: 6 June 2000 相似文献
775.
Chemical synapses are highly specialized cell–cell junctions designed for efficient signaling between nerve cells. Distinct
cytoskeletal matrices are assembled at either side of the synaptic junction. The presynaptic cytomatrix at the active zone
(CAZ) defines and organizes the site of neurotransmitter release from presynaptic nerve terminals. The postsynaptic density
(PSD) tethers neurotransmitter receptors and the postsynaptic signal transduction machinery. Recent progress in the identification
and characterization of novel CAZ and PSD components has revealed new insights into the molecular organization and assembly
mechanisms of the synaptic neurotransmission apparatus. On the presynaptic side, Bassoon and Piccolo, two related giant proteins,
are crucially involved in scaffolding the CAZ. On the postsynaptic side, two families of multi-domain adaptor proteins, the
MAGuKs (membrane-associated guanylate kinase homologs) and the ProSAP (proline-rich synapse-associated protein, also termed
Shank) family members are thought to be major organizing molecules of the PSD. 相似文献
776.
The GPS recorder consists of a GPS receiver board, a logging facility, an antenna, a power supply, a DC-DC converter and
a casing. Currently, it has a weight of 33 g. The recorder works reliably with a sampling rate of 1/s and with an operation
time of about 3 h, providing time-indexed data on geographic positions and ground speed. The data are downloaded when the
animal is recaptured. Prototypes were tested on homing pigeons. The records of complete flight paths with surprising details
illustrate the potential of this new method that can be used on a variety of medium-sized and large vertebrates.
Received: 2 February 2000 / Accepted in revised form: 17 April 2000 相似文献
777.
778.
William J Long Ronald E Majors 《环境化学》2006,25(3):381-383
大气中的挥发性羰基化合物可以通过2,4-二硝基苯肼(DNPH)原位衍生化而被捕集.采用反相HPLC 可以洗脱和分析这些羰基衍生物.本文采用该方法监测了美国佛蒙特州大气样品中的痕量甲醛、乙醛和丙酮. 相似文献
779.
Olanike O. Aladenola Ayodele E. Ajayi Ayorinde A. Olufayo Babatunde Ajayi 《The Environmentalist》2008,28(2):123-127
The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater
was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional
stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible
change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored
include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO2. The tensile stress obtained were 110, 104, and 95 N/mm2, while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging
test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure
over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of
specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were
no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the
suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities. 相似文献
780.
Effective recreation resource management relies on understanding visitor perceptions and behaviors. Given current and increasing
pressures on water resources, understanding crowding evaluations seems important. Beyond crowding, however, variables that
possibly relate to or influence crowding are of interest and in particular, place attachment and experience-use history (EUH).
As EUH is related to place attachment and likely affects crowding, this study explored the moderating effect of place attachment
dimensions on the relationships between EUH and visitor crowding evaluations. Water based recreationists at a U.S. Army Corps
of Engineers site were contacted onsite and asked questions related to experience-use history, crowding evaluations, place
attachment, and activity participation. Anglers and campers at the site identified similar crowding perceptions and place
attachments. Only one of eight models tested revealed a moderating effect. Specifically, place identity moderated the relationship
between the total times visited in the past twelve months and expected crowding among anglers. As such, the quest continues
to understand the relationship among these important variables. 相似文献