全文获取类型
收费全文 | 3124篇 |
免费 | 11篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 64篇 |
废物处理 | 149篇 |
环保管理 | 334篇 |
综合类 | 451篇 |
基础理论 | 1146篇 |
环境理论 | 1篇 |
污染及防治 | 642篇 |
评价与监测 | 199篇 |
社会与环境 | 181篇 |
灾害及防治 | 4篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 114篇 |
2017年 | 122篇 |
2016年 | 192篇 |
2015年 | 58篇 |
2014年 | 26篇 |
2013年 | 49篇 |
2012年 | 434篇 |
2011年 | 236篇 |
2010年 | 45篇 |
2009年 | 44篇 |
2008年 | 63篇 |
2007年 | 73篇 |
2006年 | 73篇 |
2005年 | 399篇 |
2004年 | 540篇 |
2003年 | 412篇 |
2002年 | 47篇 |
2001年 | 44篇 |
2000年 | 21篇 |
1999年 | 32篇 |
1998年 | 4篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 14篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1966年 | 2篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1961年 | 1篇 |
1957年 | 2篇 |
1928年 | 1篇 |
排序方式: 共有3171条查询结果,搜索用时 15 毫秒
941.
Edith?T.?Lammerts?Van?Bueren Paul?C.?StruikEmail author 《Journal of Agricultural and Environmental Ethics》2005,18(5):479-493
In addition to obviating the use of synthetic agrochemicals and emphasizing farming in accordance with agro-ecological guidelines, organic farming acknowledges the integrity of plants as an essential element of its natural approaches to crop production. For cultivated plants, integrity refers to their inherent nature, wholeness, completeness, species-specific characteristics, and their being in balance with their (organically farmed) environment, while accomplishing their “natural aim.” We argue that this integrity of plants has ethical value, distinguishing integrity of life, plant-typic integrity, genotypic integrity, and phenotypic integrity. We have developed qualitative criteria to ethically evaluate existing practices and have applied these criteria to assess whether current plant breeding and propagation techniques violate the integrity of crop plants. This process has resulted in a design of a holistic, scientific approach of organic plant breeding and seed production. Our evaluation has met considerable criticism from mainstream (crop) scientists. We respond to the following questions: (1). Can ethics be incorporated into objective crop sciences? (2). What is the nature of the intrinsic value of plants in organic farming? We argue that criteria to take integrity into account can only be assessed from a holistic perspective and we show that a holistic approach is needed to design such ethical notions in a consistent way. The ethical notions have been further elaborated by formulating human responsibility and respect towards crop plants. Responsibility and respect can only be shown by providing crop plants the right to be nurtured and to express natural behavior at all levels of integrity. 相似文献
942.
Ali?Mohammed?OumerEmail author Andreas?de Neergaard 《Environment, Development and Sustainability》2011,13(3):547-564
The aim of this paper is to disclose livelihood strategy-poverty links and gain a better understanding by developing typologies
of rural households. Based on qualitative and quantitative data, we group households into different typologies and explore
interactions. We identified six main agronomic strategies, four dominant livelihood diversification strategies, and income
quartiles (proxies for poverty) using cluster and principal component factor analysis. We found that nearly 82% of the surveyed
farmers in the study area belong to the bottom income quartiles while about 18% are on the upper quartiles. Households in
the bottom income quartiles engaged in casual off-farm work and cereal-dominated livelihood strategies that tend to pursue
subsistence farming by growing cereals and oil crops. Contrarily, farmers in the upper income quartiles adapted intensive
agronomic strategies by integrating root crops, legumes, and vegetables with livestock. This was largely attributed to access
to key livelihood assets such as land, livestock, education, and institutional support in which the upper quartiles were more
endowed. Improving availability of the key assets for the bottom income quartiles might be a way out of poverty and ensuring
sustainable development. It is crucial to recognize local-level heterogeneities of rural households when targeting development
interventions. 相似文献
943.
La Toya T. Kissoon Donna L. Jacob Marinus L. Otte 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1834-1841
Rumex crispus was grown under wet and dry conditions in two-chamber columns such that the roots were confined to one chamber by a 21 μm nylon mesh, thus creating a soil-root interface (‘rhizoplane’). Element concentrations at 3 mm intervals below the ‘rhizoplane’ were measured. The hypothesis was that metals accumulate near plant roots more under wetland than dryland conditions. Patterns in element distribution were different between the treatments. Under dryland conditions Al, Ba, Cu, Cr, Fe, K, La, Mg, Na, Sr, V, Y and Zn accumulated in soil closest to the roots, above the ‘rhizoplane’ only. Under wetland conditions Al, Fe, Cr, K, V and Zn accumulated above as well as 3 mm below the ‘rhizoplane’ whereas La, Sr and Y accumulated 3 mm below the ‘rhizoplane’ only. Plants on average produced 1.5 times more biomass and element uptake was 2.5 times greater under wetland compared to dryland conditions. 相似文献
944.
Larvae of marine organisms often need specific resources or environments at settlement, and their success at settlement might be strongly influenced by the abundance and distribution of such specific resources. The larvae of hermit crabs need small shells to settle, so it is thought that the distribution and abundance of small shells influence the settlement pattern of hermit crabs. To investigate the influence of small shell distribution on the settlement of pagurid hermit crab larvae, we conducted a field experiment at an intertidal rocky shore in Hakodate Bay, Japan. From the line-transect sampling in the field, we found that Pagurus middendorffii settled extensively in the offshore side of the intertidal zone while P. nigrofascia settled in the uppermost area of the intertidal zone. Small shells were most abundant in a narrow shallow trough, slightly offshore from the uppermost area of the intertidal zone. For both species, settler abundance was high where adults were abundant, but settler abundance did not appear to be related to shells abundance. An experiment to clarify settlement patterns showed that larval recruits tended to be similar to those in the line-transect sampling of settlers. Thus shells may not be a primary factor affecting settlement patterns at relatively large scale within the intertidal flat. However, when we analyzed the relationship of settlers and shells separately within each transect, the distribution of settlers was well explained by shell resource availability. Therefore on a smaller scale, shell availability may influence the number of settlers. Settlement periods of P. middendorffii and P. nigrofascia fully overlapped, so their larvae probably were affected by similar transport factors, such as current and tidal movement. Nevertheless they showed different spatial patterns of settlement.Communicated by T. Ikeda, Hakodate 相似文献
945.
Anne?CharmantierEmail author Philippe?Perret 《Behavioral ecology and sociobiology》2004,56(4):360-365
We tested the effect of manipulation of breeding density on the occurrence of extra-pair paternity in a blue tit (Parus caeruleus) population during two consecutive years. In a homogeneous oak forest, nest-box manipulation provided a high density plot (plot A, 1.10 and 1.32 pairs/ha) and a low density plot (plot B, 0.43 and 0.46 pairs/ha). Microsatellite analysis on 91 broods revealed a higher proportion of extra-pair paternity in broods in plot A (mean of 17.2%) than in plot B (mean of 11.4%). A correlative approach showed that the proportion of extra-pair young in broods was affected by the number of breeding neighbours within 100 m around the nest-box, by the distance to the nearest breeding neighbour and by an additional plot effect. However, the nearest neighbours accounted for only 39.3% of extra-pair paternities and distance to extra-pair fathers was significantly higher than the nearest neighbour distance in both plots. This implies that the effect of density on the occurrence of extra-pair paternities is associated with active female choice to enhance the brood fitness. Although there were more extra-pair young in broods when density was high, the number of extra-pair fathers did not increase and stayed close to one. We suggest that density increases the cost of mate guarding by males, thereby increasing the possibility for females to solicit extra-pair paternities to the cuckolding male they have chosen. Finally, we discuss why correlatives approaches do not always show evidence for an effect of breeding density on extra-pair paternity occurrence.Communicated by M. Soler 相似文献
946.
Two inhibitors, triethanolamine (TEA) and monoethanolamine (MEA), were tested for their ability to prevent the de novo formation
of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) on sinter plant fly ash. The amounts of both PCDDs and PCDFs, formed
by thermal treatment of the fly ash, decreased when inhibitors were added. Up to 90% reduction of the PCDD/Fs formation was
reached when 2 wt % monoethanolamine was mixed with fly ash. The temperatures tested, 325 and 400 °C, did not affect the inhibition
activity. However, a longer reaction time, 4 h instead of 2 h, gave higher percentages of PCDD/Fs reduction. The laboratory
results show that ethanolamines reduce the dioxins formation on sinter plant fly ash under various conditions of temperature
and reaction time. Moreover, factory tests performed in parallel at a sinter plant are in good agreement with the laboratory
experiments, thus confirming that the use of ethanolamine inhibitors is an appropriate technique for the prevention of dioxins
emissions from sintering processes.
Electronic Publication 相似文献
947.
The recently reported Jeholornis represents the only known bird with a complete long skeletal tail except for Archaeopteryx. Two newly discovered specimens referable to Jeholornis provide some important new information about its anatomy. The tail of Jeholornis is much longer than that of Archaeopteryx and comprises a maximum of 27 caudal vertebrae compared with only 23 in Archaeopteryx. More interestingly, the tail feathers are shaped more like those of dromaeosaurs than those of Archaeopteryx. We conclude that the common ancestor of birds must have a more primitive tail than that in Archaeopteryx, confirming the side branch position of Archaeopteryx in the early avian evolution. The synsacrum is composed of six sacrals, representing a transitional stage between Archaeopteryx and more advanced birds. The scapula of Jeholornis has a dorso-laterally exposed glenoid facet, and the coracoid has a supracoracoid foramen. The presence of a pair of fenestrae
in the sternum of Jeholornis has further implications for the air-sac system in early birds.
Electronic Supplementary Material The online version of this article (doi: contains supplementary material, which is available to authorized users. 相似文献
948.
Henry?M.?SpliethoffEmail authorView authors OrcID profile
return OK on get Rebecca?G.?Mitchell Hannah?Shayler Lydia?G.?Marquez-Bravo Jonathan?Russell-Anelli Gretchen?Ferenz Murray?McBride 《Environmental geochemistry and health》2016,38(4):955-971
Urban community gardens provide affordable, locally grown, healthy foods and many other benefits. However, urban garden soils can contain lead (Pb) that may pose risks to human health. To help evaluate these risks, we measured Pb concentrations in soil, vegetables, and chicken eggs from New York City community gardens, and we asked gardeners about vegetable consumption and time spent in the garden. We then estimated Pb intakes deterministically and probabilistically for adult gardeners, children who spend time in the garden, and adult (non-gardener) household members. Most central tendency Pb intakes were below provisional total tolerable intake (PTTI) levels. High contact intakes generally exceeded PTTIs. Probabilistic estimates showed approximately 40 % of children and 10 % of gardeners exceeding PTTIs. Children’s exposure came primarily from dust ingestion and exposure to higher Pb soil between beds. Gardeners’ Pb intakes were comparable to children’s (in µg/day) but were dominated by vegetable consumption. Adult household members ate less garden-grown produce than gardeners and had the lowest Pb intakes. Our results suggest that healthy gardening practices to reduce Pb exposure in urban community gardens should focus on encouraging cultivation of lower Pb vegetables (i.e., fruits) for adult gardeners and on covering higher Pb non-bed soils accessible to young children. However, the common practice of replacement of root-zone bed soil with clean soil (e.g., in raised beds) has many benefits and should also continue to be encouraged. 相似文献
949.
Summary. Host selection in tree-killing bark beetles
(Coleoptera: Scolytidae) is mediated by a complex of semiochemical
cues. Using gas chromatographic-electroantennographic
detection (GC-EAD) and GC-mass spectrometric
analyses, we conducted a comparative study of the electrophysiological
responses of four species of tree-killing bark
beetles, the Douglas-fir beetle, Dendroctonus pseudotsugae,
Hopkins, the mountain pine beetle, D. ponderosae Hopkins,
the spruce beetle, D. rufipennis Kirby, and the western balsam
bark beetle, Dryocoetes confusus Swaine, to volatiles
captured by aeration of 1) bole and foliage of four sympatric
species of conifers, Douglas-fir, Pseudotsuga menziesii
(Mirb.) Franco, lodgepole pine, Pinus contorta var. latifolia
Engelm., interior spruce, Picea engelmannii x glauca, and
interior fir, Abies lasiocarpa x bifolia, and 2) con- and
heterospecific beetles at three stages of attack. We identified
13 monoterpenes in the conifers and nine compounds in the
volatiles of beetles that elicited antennal responses. There
was no qualitative difference in the terpene constitution of
the four species of conifers and very little difference across
beetle species in their antennal response to compounds from
conifers or beetles. The lack of species-specific major or
minor components in conifers suggests that beetles would
need to detect differences in the ratios of different compounds
in conifers to discriminate among them. Attraction to
hosts and avoidance of nonhost conifers may be accentuated
by perception of compounds emitted by con- and heterospecific
beetles, respectively. The 22 compounds identified
are candidate semiochemicals with potential behavioural
roles in host location and discrimination. 相似文献
950.