全文获取类型
收费全文 | 290篇 |
免费 | 0篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 3篇 |
废物处理 | 7篇 |
环保管理 | 15篇 |
综合类 | 192篇 |
基础理论 | 23篇 |
污染及防治 | 34篇 |
评价与监测 | 4篇 |
社会与环境 | 13篇 |
出版年
2022年 | 5篇 |
2018年 | 9篇 |
2015年 | 4篇 |
2013年 | 7篇 |
2012年 | 4篇 |
2011年 | 3篇 |
2010年 | 6篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1994年 | 3篇 |
1992年 | 5篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1967年 | 3篇 |
1963年 | 5篇 |
1962年 | 8篇 |
1961年 | 4篇 |
1960年 | 6篇 |
1959年 | 3篇 |
1958年 | 9篇 |
1957年 | 12篇 |
1956年 | 13篇 |
1955年 | 17篇 |
1954年 | 6篇 |
1953年 | 6篇 |
1952年 | 4篇 |
1950年 | 5篇 |
1941年 | 2篇 |
1939年 | 4篇 |
1938年 | 4篇 |
1937年 | 3篇 |
1935年 | 5篇 |
1933年 | 2篇 |
1931年 | 3篇 |
1930年 | 5篇 |
1929年 | 3篇 |
1924年 | 2篇 |
1922年 | 2篇 |
1920年 | 2篇 |
1913年 | 3篇 |
排序方式: 共有291条查询结果,搜索用时 442 毫秒
171.
Scenarios of global bioenergy production: The trade-offs between agricultural expansion, intensification and trade 总被引:1,自引:0,他引:1
Hermann Lotze-Campen Alexander Popp Tim Beringer Christoph Müller Alberte Bondeau Stefanie Rost Wolfgang Lucht 《Ecological modelling》2010,221(18):2188-2196
Increased future demands for food, fibre and fuels from biomass can only be met if the available land and water resources on a global scale are used and managed as efficiently as possible. The main routes for making the global agricultural system more productive are through intensification and technological change on currently used agricultural land, land expansion into currently non-agricultural areas, and international trade in agricultural commodities and processed goods. In order to analyse the trade-offs and synergies between these options, we present a global bio-economic modelling approach with a special focus on spatially explicit land and water constraints as well as technological change in agricultural production. For a global bioenergy demand scenario reaching 100 ExaJoule (EJ) until 2055 we derive a required rate of productivity increase on agricultural land between 1.2 and 1.4 percent per year under different land allocation options. A very high pressure for yield increase occurs in Sub-Saharan Africa and the Middle East, even without additional bioenergy demand. Moreover, we analyse the implicit values (shadow prices) of limited water resources. The shadow prices for bioenergy are provided as a metric for assessing the trade-offs between different land allocation options and as a link between the agricultural and energy sector. 相似文献
172.
Daniel Aguilera-Olivares Camila Burgos-Lefimil Wara Melendez Luis Flores-Prado Hermann M. Niemeyer 《Chemoecology》2016,26(5):163-172
Nestmate recognition is a necessary capacity for the occurrence of discrimination between nestmate and non-nestmate individuals. In one-piece nesting termites, which nest and forage in a single piece of wood, nestmate recognition is poorly studied mainly because the probability of encountering exogenous individuals is low in comparison with separate-piece nesting termites. Previous work described that production of soldiers of Neotermes chilensis, a one-piece nesting termite, increased when the risk of invasion of their colony increased, for example when neighboring colonies were present in the same nesting substrate and members of different colonies met when digging galleries. If soldiers are to fulfill their defensive role under these circumstances, they should show nestmate recognition ability; moreover, based on work on other social insects, such nestmate recognition should be based on cuticular compounds (CC). Bioassays were performed in which a soldier of N. chilensis was confronted with a nestmate or non-nestmate primary reproductive, pseudergate or another soldier, and in which a soldier was confronted with untreated and with CC-deprived dead primary reproductives. The results showed that soldiers were indeed more aggressive toward non-nestmates than nestmates for all castes, and that this discrimination was mediated mainly by qualitative (simple matching coefficient) and quantitative (Renkonen index) differences in CC. 相似文献
173.
174.
175.
Hermann A. Kahle 《Die Naturwissenschaften》1957,44(22):573-578
176.
Summary The biology and behavior of Xylocopa virginica L. were followed in the area of Athens, Georgia (USA) from August 1973 until September 1974. Several nests were X-rayed regularly during the developmental period of the bees, and information about the life cycle and development was obtained. The bees emerge in June and stay in their nests with their sibs throughout the summer, fall, and winter, leaving only occasionally on warm days to search for nectar as food. In March and April males defend nest-side territories and mate with most females. The males die in the late spring and the females dig nests, provision them, and rear up to 8 or 9 bees in each nest. Many females live 2 years, and often 2 to 3 females are present in each nest, but only 1 works and lays eggs. Emergence of adults from pupae is nearly synchronized, irrespective of age. 相似文献
177.
Hermann Berg 《Die Naturwissenschaften》1960,47(14):320-321
178.
179.
180.
Olfactory learning may occur at different stages of insect ontogeny. In parasitoid wasps, it has been mostly shown at adult
emergence, whilst it remains controversial at pre-imaginal stages. We followed larval growth of the parasitoid wasp, Aphidius ervi Haliday, inside the host aphid, Acyrthosiphom pisum Harris, and characterised in detail the behaviour of third instar larvae. We found that just before cocoon spinning begins,
the third instar larva bites a hole through the ventral side of the mummified aphid exoskeleton. We then evaluated whether
this period of exposure to the external environment represented a sensitive stage for olfactory learning. In our first experiment,
the third instar larvae were allowed to spin their cocoon on the host plant (Vicia faba L.) surface or on a plastic plate covering the portion of the host plant exposed to the ventral opening. Recently emerged
adults of the first group showed a preference for plant volatiles in a glass Y-olfactometer, whereas no preference was found
in adults of the second group. In a second experiment, during the period in which the aphid carcass remains open or is being
sealed by cocoon spinning, third instar larvae were exposed for 24 h to either vanilla odours or water vapours as control.
In this experiment, half of the parasitoid larvae were later excised from the mummy to avoid further exposure to vanilla.
Adult parasitoids exposed to vanilla during the larval ventral opening of the mummy showed a significant preference for vanilla
odours in the olfactometer, regardless of excision from the mummy. The larval behaviour described and the results of the manipulations
performed are discussed as evidences for the acquisition of olfactory memory during the larval stage and its persistence through
metamorphosis. 相似文献