全文获取类型
收费全文 | 287篇 |
免费 | 4篇 |
国内免费 | 10篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 3篇 |
环保管理 | 36篇 |
综合类 | 99篇 |
基础理论 | 72篇 |
环境理论 | 1篇 |
污染及防治 | 63篇 |
评价与监测 | 17篇 |
社会与环境 | 7篇 |
灾害及防治 | 1篇 |
出版年
2022年 | 6篇 |
2021年 | 5篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 14篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 11篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1988年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1971年 | 3篇 |
1970年 | 7篇 |
1969年 | 2篇 |
1966年 | 3篇 |
1964年 | 5篇 |
1961年 | 4篇 |
1960年 | 2篇 |
1959年 | 4篇 |
1940年 | 2篇 |
1938年 | 5篇 |
1935年 | 3篇 |
1934年 | 3篇 |
1925年 | 2篇 |
1920年 | 2篇 |
排序方式: 共有301条查询结果,搜索用时 125 毫秒
91.
92.
Sabine Bauer Volker Witte Melanie Böhm Susanne Foitzik 《Behavioral ecology and sociobiology》2009,64(1):45-56
Ant social parasites use chemical warfare to facilitate host colony takeover, which is a critical but recurring step in their
life cycle. Many slave-making ants use the secretion of the Dufour gland to manipulate host behaviour during parasitic nest
foundation and slave raids. Harpagoxenus sublaevis applies this chemical weapon onto defending Leptothorax host workers, which elicits deadly fights amongst them. Host species are expected to evolve counter-adaptations against this
behavioural manipulation and in this study we investigated the geographic structure of this co-evolving trait. We compared
the effectiveness of the parasitic gland secretion from different H. sublaevis populations in host colonies from various sites and analysed the occurrence of local adaptation. The two host species L. muscorum and L. acervorum generally showed different responses to the parasites’ chemical weapon: L. acervorum attacked nestmates treated with Dufour gland secretion, while L. muscorum workers fled. Flight, instead of intraspecific fights, is an adaptive host reaction as it results in fewer host fatalities
during raids. Beside interspecific host differences, we found a geographic mosaic of host resistance: parasites from a German
population strongly manipulated the behaviour of both sympatric Leptothorax populations. Russian or Italian hosts instead did not react with intracolonial aggression, but fled when confronted with
the gland secretion of their sympatric parasite. Not only variation in host resistance explains differences in the effectiveness
of the parasitic gland secretion but also interpopulational differences in its chemical composition, which were revealed by
gas chromatography and mass spectrometry. 相似文献
93.
94.
W. Winiwarter H. Bauer A. Caseiro H. Puxbaum 《Atmospheric environment (Oxford, England : 1994)》2009,43(7):1403-1409
Atmospheric concentration measurements of tracers for primary biological aerosol particles (PBAPs) have been used to obtain estimates of their release into the atmosphere. Emission flux data of surrogate compounds, for which concurrent concentration measurements were available, were used to quantify the release of PBAPs as PM10 mass. Results indicate fungal spores to be the most important contributors. One other main source is plant debris. Area-based emission rates of 24 kg km?2 and year (range 6–90) have been assessed. Results scaled for Europe indicate a contribution of PBAPs to PM10 concentrations in the low percentage range, with a maximum in summer when concentration levels are small. This is consistent with the range of measurements. Despite of the large uncertainties, results contribute to clarify the potential contribution of biological particles to global load of particle mass. 相似文献
95.
96.
The attitudes and behaviours of private landholders toward the conservation of a highly transformed and critically endangered
habitat, Overberg Coastal Renosterveld (OCR) (a grassy shrubland of the Cape Floral Region, South Africa) are described. Personal,
semistructured interviews were conducted with landholders, representing 40 properties in the Overberg region, on topics such
as management and utilisation of OCR, the depth of their knowledge of its conservation importance, what they perceive its
value to be, and the extent of their willingness to conserve it. General attitudes toward conservation incentives and provincial
conservation authorities were also investigated. Farmers more willing to conserve were younger, did not necessarily have a
better education, and owned larger farms (>500 ha) with a greater amount of remnant renosterveld (>300 ha) than those less
willing to conserve. Attitudes toward the OCR were largely negative, related to associated problem plants and animals and
the fact that it is believed not to be economically advantageous to retain it. However, farmers are of the opinion that provision
of incentives and increased extension support will provide practical positive inducements for conservation. Landholder education
is paramount to prevent further transformation of critically endangered habitats. The success of private-conservation programs
depends on the attitudes of landowners toward (1) the particular habitat or species to be conserved (which can vary depending
on the type of land use practised and the associated benefits and disadvantages of that habitat type); (2) the conservation
agency or extension officers responsible for that area; and (3) willingness of landowners to participate in a conservation
program, which is influenced by landowner age, farm size, and the amount of natural habitat left to conserve. 相似文献
97.
Numerical simulation of reactive processes in an experiment with partially saturated bentonite 总被引:2,自引:0,他引:2
Bentonites are preferred materials for use as engineered barriers for high-level nuclear waste repositories. Simulation of geochemical processes in bentonite is therefore important for long-term safety assessment of those repositories. In this work, the porewater chemistry of a bentonite sample subject to simultaneous heating and hydration, as studied by Cuevas et al. [Cuevas, J., Villar, M., Fernández, A., Gómez, P., Martín, P., 1997. Porewaters extracted from compacted bentonite subjected to simultaneous heating and hydration. Applied Geochemistry 12, 473-481.], was assessed with a non-isothermal reactive transport model by coupling the geochemical software PHREEQC2 with the object-oriented FEM simulator GeoSys/RockFlow. Reactive transport modelling includes heat transport, two-phase flow, multicomponent transport and geochemical reactions in the liquid phase, i.e. ion exchange, mineral dissolution/precipitation and equilibrium reactions. Simulations show that the easily soluble minerals in bentonite determine the porewater chemistry. Temperature affects both two-phase flow and geochemical reactions. Porosity change due to dissolution/precipitation is low during the experiment. However, changes of the effective porosity caused by bentonite swelling can be very large. The simulated results agree well with the experimental data. 相似文献
98.
99.
As coastal development increases so too does the number of artificial floating and permanent structures. It has been postulated that because of their size, many houseboats are similar to permanent structures in that they shade a significant portion of the benthos and thereby limit production by benthic flora. On the other hand, these structures can benefit biotic communities by providing sites for attachment of organisms in a substrate-limited environment and both habitat and food sources for fish. In this study, we examined whether houseboats benefit or harm the ecological integrity of a typical seagrass dominated system, at La Parguera, Puerto Rico. We performed a benthic survey to compare the diversity and health of seagrasses under houseboats to that at control locations. Species diversity (0-0.79) varied significantly among sites, but this variability was not attributed to the houseboats. Rather, the variability appeared related to the proximity of the study locations to new development along the shoreline. Average seagrass blade density and length were 52.7 blades/m(-2) and 23.6 cm, respectively. Neither parameter differed between houseboat and control areas; however, both varied significantly among sites. In addition, boat hulls were heavily encrusted with invertebrates. The overall averages of species diversity and richness of sessile organisms on hulls of the houseboats were 1.13 and 4.83, respectively. Fish also utilized these structures. Our results indicate that houseboats did not directly harm the seagrass communities at La Parguera primarily because of sound environmental management of wastes and mooring techniques. 相似文献
100.
Heidi Wienert George Roy C. Sidle 《Journal of the American Water Resources Association》1995,31(6):1051-1062
ABSTRACT: Geomorphic processes may partly determine channel geometry. Soil particle uplift during freezing and thawing cycles and bank sloughing during wetting and drying periods were observed. Soil properties and channel dimension were measured to determine the dominant processes controlling channel geometry in eight small (mean area 0.096 km2) drainages in Logan Canyon, Utah. Soil cohesion was low (plasticity index > 15) for all but one of the drainages sampled. Basin scale geomorphic variables were examined to determine if they control channel dimension. Bankfull width was highly correlated to channel length and valley length with r2 values of 0.85 and 0.84, respectively. A strong canonical correlation (0.64) showed that distance from the watershed divide, bank liquid limit, and bank sand content were effective predictor variables of bankfull width and depth. The interrelations between geomorphic and pedogenic processes were the strongest determinants of ephemeral channel dimension in this study. 相似文献