全文获取类型
收费全文 | 386篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
安全科学 | 2篇 |
废物处理 | 4篇 |
环保管理 | 9篇 |
综合类 | 204篇 |
基础理论 | 66篇 |
污染及防治 | 86篇 |
评价与监测 | 10篇 |
社会与环境 | 8篇 |
出版年
2021年 | 3篇 |
2018年 | 4篇 |
2016年 | 5篇 |
2014年 | 8篇 |
2013年 | 12篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 7篇 |
2007年 | 21篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1987年 | 3篇 |
1983年 | 3篇 |
1981年 | 4篇 |
1978年 | 3篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 5篇 |
1964年 | 8篇 |
1963年 | 11篇 |
1962年 | 4篇 |
1961年 | 7篇 |
1960年 | 5篇 |
1959年 | 6篇 |
1958年 | 10篇 |
1957年 | 7篇 |
1956年 | 7篇 |
1955年 | 12篇 |
1954年 | 6篇 |
1952年 | 4篇 |
1951年 | 3篇 |
1950年 | 6篇 |
1947年 | 5篇 |
1943年 | 6篇 |
1939年 | 4篇 |
1924年 | 3篇 |
排序方式: 共有389条查询结果,搜索用时 187 毫秒
321.
Gerhard Gries Regine Gries Paul W. Schaefer Tadao Gotoh Yasutomo Higashiura 《Die Naturwissenschaften》1999,86(5):235-238
Pheromone extract of female pink gypsy moth, Lymantria mathura, was analyzed by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometry (MS),
employing fused silica columns coated with DB-5, DB-210, or DB-23 and a custom-made GC column that separated enantiomers of
unsaturated epoxides. These analyses revealed (9R,10S)-cis–9,10-epoxy-Z3,Z6-nonadecadiene [termed here (+)-mathuralure] and (9S,10R)-cis–9,10-epoxy-Z3,Z6-nonadecadiene [termed here (–)-mathuralure] at a 1 : 4 ratio as major candidate pheromone components. In field experiments
in northern Japan (Morioka, Iwate Prefecture and Bibai, Hokkaido Prefecture), (+)- and (–)-mathuralure at a ratio of 1 : 4,
but not 1 : 1 or singly, were attractive to male L. mathura. This is the first demonstration that attraction of male moths required the very same ratio of pheromone enantiomers as produced
by conspecific females. Whether L. mathura employ different blend ratios in different geographic areas, and the role of five additional candidate pheromone components
identified in this study remains to be investigated.
Received: 29 October 1998 / Accepted in revised form: 29 December 1998 相似文献
322.
323.
324.
325.
326.
327.
328.
Summary In Myotis emarginatus, the patterns of echolocation sounds vary with different foraging habitats: In commuting flights the echolocation sounds are linearly frequency modulated sweeps that start at about 100 kHz, terminate at 40 kHz, and have a duration of 1–3 ms. They consist of a loud first harmonic. The second and third harmonics are at least 15 dB fainter than the first one and often undetectable. A distinctly different type of sound is emitted when the bats search for flying insects in open spaces. The sounds are reduced in bandwidth and elongated by a constant frequency component that follows the initial frequency modulated part. Typically, sounds start at about 94 kHz and terminate in a constant frequency component at about 40–45 kHz. The average duration of the constant frequency tail is 2.8 ms; this approximately doubles the length of the pulse, with the longest recorded sound lasting 7.2 ms. When bats are foraging near and within foliage, and gleaning prey from foliage, echolocation sounds are brief (average 1 ms) frequency modulated pulses with a broad bandwidth. The pulses start at about 105 kHz and sweep down to 25 kHz. During gleaning within a building, the frequency range of the sounds is shifted to higher frequencies and extends from 124 to 52 kHz. When the bats forage for aireal insects in a confined area that creates echo-clutter, they emit sounds similar to those used during gleaning within buildings except that sound durations are extended to about 1.8 ms. In each foraging area, the echolocation sounds emitted during the search for and approach to prey are similar in structure. Sound and pause durations are reduced in the approach phase. Irrespective of foraging style and habitat, immediately before capture the bat emits a rapid and stereotyped sequence of 2-10 echolocation pulses (final buzz). These pulses are brief (0.2–0.5 ms), frequency modulated sounds with a reduced bandwidth. The sounds start at 45 kHz and sweep down to 35–20 kHz. The repetition rate is increased up to 200 pulses/s.
Offprint requests to: G. Neuweiler 相似文献
329.
Martin Paulus Roland Klein Gerhard Wagner Paul Müller 《Environmental science and pollution research international》1996,3(3):169-177
The environmental specimen banking program (ESB) of the Federal Republic of Germany implies a collection of specimens from representative areas of Germany, stored under stable conditions for deferred analysis. It is an important part of the ecological assessment program. The ecological concept is presented as the frame of the entire ESB program. It is based on the selection of representative sampling areas and specimens. Standard operating procedures (SOP’s) for sampling and characterization of specimens, as well as sampling designs specific to the areas, are presented as further important parts of the quality assurance system in relation to the correct sampling of specimens. 相似文献
330.
Total environmental and compartmental residence times as a measure for persistence as well as indicators for long-range transport potential (LRTP) have been derived from global geo-referenced modelling and LRTP is characterized in two geographic directions for the first time. A dynamic multicompartment chemistry-transport model (MCTM) was used to study the fate of the insecticides DDT and alpha-hexachlorocyclohexane (alpha-HCH) during the first 2 years upon entry. The indicators for LRTP were defined such as to address the tendencies of substance distributions to migrate ('plume displacement', PD) and to spread into remote areas ('spatial spreading', SS). The indicators deliver values as function of time upon entry. With the aim to address the effect of location of entry on environmental fate, scenarios of emission from the territories of seven countries were studied. It was found that the effect of location of entry on the spatial scale of countries (400-4000 km) is significant for the compartmental distribution and the inter-compartmental mass exchange fluxes (e.g., number of atmospheric cycles, 'hops'). Location of entry introduces uncertainties in the order of a factor of 5 for the total environmental residence time, tau(overall), and a factor of 5-20 for PD and SS. For the 2nd year upon entry into the environment, tau(overall)=317-1527 days are predicted for DDT and 101-463 days for alpha-HCH. The influence of location of entry does affect the substance ranking, i.e. we cannot simply state that DDT is more persistent than alpha-HCH, but for one scenario studied, application in China, the opposite is predicted. Precipitation patterns proved to be significant, besides other climate parameters, for atmospheric residence time. Integration of the location of entry in chemicals risk assessments is therefore recommended. In general, persistence and some indicators for LRTP, pertinent to their definition, refer to the fate of a large fraction, e.g., 63% (=1-1/e) or 90%, but not the total substance burden. The choice of this fraction may have the consequence of a normative step which defines the spatial and temporal extensions of a related chemicals risk assessment and may affect substance ranking. 相似文献