全文获取类型
收费全文 | 3744篇 |
免费 | 3篇 |
国内免费 | 122篇 |
专业分类
安全科学 | 85篇 |
废物处理 | 156篇 |
环保管理 | 349篇 |
综合类 | 421篇 |
基础理论 | 245篇 |
污染及防治 | 1851篇 |
评价与监测 | 488篇 |
社会与环境 | 233篇 |
灾害及防治 | 41篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 6篇 |
2018年 | 2篇 |
2017年 | 10篇 |
2016年 | 1篇 |
2015年 | 12篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 347篇 |
2011年 | 464篇 |
2010年 | 61篇 |
2009年 | 105篇 |
2008年 | 448篇 |
2007年 | 425篇 |
2006年 | 356篇 |
2005年 | 285篇 |
2004年 | 247篇 |
2003年 | 249篇 |
2002年 | 191篇 |
2001年 | 149篇 |
2000年 | 104篇 |
1999年 | 50篇 |
1998年 | 6篇 |
1997年 | 26篇 |
1996年 | 13篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 25篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 25篇 |
1984年 | 12篇 |
1983年 | 22篇 |
1982年 | 12篇 |
1981年 | 15篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1974年 | 3篇 |
排序方式: 共有3869条查询结果,搜索用时 15 毫秒
611.
In contrast to an open environment where a specific celestial cue is predominantly used, visual contrast of canopies against the sky through the gap, known as canopy cues, is known to play a major role for visually guided insect navigators in woodland habitats. In this paper, we investigated whether a subsocial shield bug, Parastrachia japonensis, could gauge direction using canopy cues on a moonless night. The results show that they could perform the round trip foraging behaviour even in an experimental arena with only an artificial round gap opened in the ceiling of the arena and adjust their homing direction for a new azimuth when the gap was rotated. Thus, P. japonensis can use slightly brighter canopy cues as a compass reference but not complex landmarks during nocturnal homing behaviour. 相似文献
612.
Stenusine is well known as the alkaloid, discharged by the rove beetle, genus Stenus Latreille (Coleoptera, Staphylinidae). The Stenus beetles employ the alkaloid as an escape mechanism when on water surfaces. In the case of danger, they lower their abdomen and emit stenusine from their pygidial glands. Stenusine shows a low surface tension and therefore a high spreading pressure; these properties propel the beetle quickly over the water. Many Steninae do not live in habitats with open waters, but in detritus, leaf litter, mosses, etc. This raises the possibility that stenusine might also have another function, e.g., as antibiotic or fungicide. Stenus beetles show an intense grooming behaviour. With gas chromatography-mass spectrometry analyses we could prove that they cover themselves with their secretion. To tests its antimicrobial properties we conducted agar diffusion tests with stenusine and norstenusine, another substance that is abundant in most Stenus species. Both compounds have an antimicrobial effect on entomopathogenic bacteria and fungi. Stenusine not only allows for an extraordinary method of locomotion on water surfaces, it also protects the Steninae from being infested with microorganisms. 相似文献
613.
Tan K Yang MX Radloff SE Hepburn HR Zhang ZY Luo LJ Li H 《Die Naturwissenschaften》2008,95(12):1165-1168
Although the structure of the dance language is very similar among species of honeybees, communication of the distance component
of the message varies both intraspecifically and interspecifically. However, it is not known whether different honeybee species
would attend interspecific waggle dances and, if so, whether they can decipher such dances. Using mixed-species colonies of
Apis cerana and Apis mellifera, we show that, despite internal differences in the structure of the waggle dances of foragers, both species attend, and act
on the information encoded in each other’s waggle dances but with limited accuracy. These observations indicate that direction
and distance communication pre-date speciation in honeybees. 相似文献
614.
Web spiders are considered to have expanded their habitats from dim to bright environments during the evolutionary history.
Because they are sedentary predators exposed to the sun, they may have developed a suite of adaptive traits to cope with thermal
stress. We examined the critical thermal maximum, spectral reflectance of solar energy by the body surface, and surface–volume
ratio (SVR) for 11 spider species. Analysis of the four genera having a pair of species inhabiting both bright and dim environments
showed that species in bright environments exhibited higher lethal temperatures, but spectral reflectance and SVR did not
differ. Independent contrasts using the 11 species indicated that critical thermal maximum was positively correlated with
spectral reflectance and spectral reflectance was negatively correlated with SVR. These results suggest that physiological
tolerance to high temperatures and a biophysical mechanism to reduce heat gain evolved jointly during the history of habitat
expansion in araneoid spiders. 相似文献
615.
The bumblebee Bombus terrestris is not only an effective pollinator, but also a potential invasive alien species outside its native range. Recently, nearly
30% of queens of the Japanese native species Bombus hypocrita sapporoensis and B. hypocrita hypocrita were estimated to copulate with B. terrestris males in the field, suggesting that indigenous bumblebees could be genetically deteriorated through hybrid production with
the introduced species. In this study, we evaluated hybrid production between the introduced B. terrestris and the indigenous B. hypocrita sapporoensis under laboratory conditions. The hatching rate of eggs derived from interspecific matings was 0% and 8.6% depending on the
direction of the cross, which was significantly lower than that from intraspecific matings of B. terrestris (76.9%) and B. hypocrita sapporoensis (78.9%). Genetic studies using microsatellite markers revealed that both haploid and diploid individuals were present in
the egg stage, whereas all hatched larvae were haploid. In addition, histological studies revealed that eggs derived from
interspecific matings terminated development 2 days after oviposition. These results strongly suggested that eggs derived
from interspecific matings are inviable due to post-mating isolation mechanisms. Mass release of exotic pollinators could
cause serious population declines of native bumblebee species. 相似文献
616.
A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis was isolated from a soil contaminated with electrical transformer ?uid for over sixty years using Aroclor 1221 as an enrichment substrate. The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4'- and 4,4'-dichlorobiphenyl as well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustaine... 相似文献
617.
This paper presents daily, monthly and yearly variations of PAH mass concentrations measured in PM(10) particle fraction, collected at one measuring site in Zagreb air between 2001 and 2004, and seasonal differences in PAH mass concentrations in PM(10) samples collected from 21 March 2003 to 20 March 2004. Twenty-four hour samples were taken in the northern residential part of Zagreb using a low-volume (50 m(3)) sampler and glass or quartz filters. The analysis was performed using a high-performance liquid chromatograph (HPLC) and fluorescence detector with changeable excitation and emission wavelength. The annual average mass concentrations over the four-year measuring period for BaP ranged from 1.17 ng/m(3) in 2004 to 1.87 ng/m(3) in 2003 and were below the limit value (2 ng/m(3)) set by the Ordinance on Recommended and Limit Air Quality Values in Croatia. The highest concentrations of all PAHs measured in PM(10) samples collected from 21 March 2003 to 20 March 2004 were found in the winter and the lowest in the summer. Winter average of BaP was 2.94 ng/m(3) and summer average 0.12 ng/m(3). Autumn average was 2.76 ng/m(3) and was very similar to winter concentrations. Spring average of 0.58 ng/m(3) was higher than the summer average (0.12 ng/m(3)). Mass concentrations of all measured PAHs were much higher in the autumn than in the spring. Although annual averages for BaP did not exceed the limit value, autumn and winter BaP mass concentrations did, which calls for measures for reducing PAH emissions in the autumn and winter. 相似文献
618.
619.
Rhenium (Re) mobility in agricultural soils was studied in order to obtain information relevant to (99)Tc mobility in soil-to-plant systems. Since water soluble Tc and Re are highly bioavailable, extraction of Re with water was carried out in addition to a total Re determination in the soils. The geometric means of total Re for paddy field, upland field and other soils were 0.34, 0.23, and 0.28 ng g(-1), respectively, while those of water soluble Re (<0.45 microm membrane filterable) were 0.053, 0.015 and 0.008 ng g(-1), respectively. There were no differences for total Re among soil uses; however, the water soluble Re/total Re ratio was significantly higher in paddy field soils (16%) than in other soil uses (6% for upland fields and 3% for other uses). Rhenium mobility and plant availability were higher in paddy fields than in other agricultural fields, and similar phenomena would be expected for (99)Tc. 相似文献
620.
Bazała MA Gołda K Bystrzejewska-Piotrowska G 《Journal of environmental radioactivity》2008,99(7):1200-1202
We present a new protocol to study fluxes of radionuclides and other xenobiotics in saprophytic fungi. This simple method has successfully been used to evaluate transport of radiocesium in hyphae of Pleurotus eryngii and its translocation to fruitbodies. 相似文献