全文获取类型
收费全文 | 1072篇 |
免费 | 4篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 12篇 |
废物处理 | 7篇 |
环保管理 | 45篇 |
综合类 | 528篇 |
基础理论 | 241篇 |
污染及防治 | 204篇 |
评价与监测 | 30篇 |
社会与环境 | 30篇 |
灾害及防治 | 3篇 |
出版年
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 17篇 |
2014年 | 13篇 |
2013年 | 45篇 |
2012年 | 27篇 |
2011年 | 34篇 |
2010年 | 29篇 |
2009年 | 30篇 |
2008年 | 34篇 |
2007年 | 42篇 |
2006年 | 42篇 |
2005年 | 25篇 |
2004年 | 16篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 21篇 |
2000年 | 13篇 |
1999年 | 38篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 18篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1993年 | 9篇 |
1989年 | 12篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1969年 | 8篇 |
1967年 | 8篇 |
1966年 | 15篇 |
1965年 | 11篇 |
1964年 | 16篇 |
1963年 | 11篇 |
1961年 | 14篇 |
1960年 | 12篇 |
1957年 | 11篇 |
1955年 | 12篇 |
1954年 | 8篇 |
1953年 | 10篇 |
1941年 | 9篇 |
1940年 | 9篇 |
1938年 | 8篇 |
1937年 | 12篇 |
1936年 | 11篇 |
1935年 | 10篇 |
1934年 | 13篇 |
1931年 | 8篇 |
1929年 | 8篇 |
排序方式: 共有1100条查询结果,搜索用时 328 毫秒
941.
942.
943.
Klaus Riede 《Behavioral ecology and sociobiology》1983,14(1):21-27
Summary Males of the acridid species Gomphocerus rufus L. perform unusually long courtship. Following their imaginal molt, the behavior of the females changes in three stages: initial rejection of the males, passive acceptance without singing, and active attraction of a mate by singing. Females in the active state permit copulation after brief courtship or even without it.To understand the function of long courtship, two hypotheses are tested by the present experiments. Hypothesis A assumes that the long courtship of the male affects the female so as to accelerate entry into the active mating state. This is not the case: Females raised in isolation enter the active state at the same time as those that have been exposed to courtship continually. Hypothesis B assumes that the long courtship changes the behavior of a female still in the passive state to enable earlier copulation. This hypothesis is tested by longterm recording of the locomotor and singing activity of the female in the presence of a courting male. The records show that the locomotor activity of a female in the passively acceptant state is significantly reduced during male courtship. Moreover, males in the presence of a passively acceptant female court longer than when the female is in either of the two other states.It appears, therefore, that the unusually long courtship serves to keep the female near the male for a longer period of time, increasing the chance of copulation. The advantages and disadvantages of this courtship strategy are compared with those of searching for a female in the active state. 相似文献
944.
Predation of different-sized Hyperoche medusarum (Hyperiida: Amphipoda) on larvae of the Pacific herring Clupea harengus pallasi was studied in the laboratory. The attacking rate of H. medusarum was a function of herring larvae size as well as size of the predator, and varied from 0.15 to 0.95 larvae attacked h-1 per hyperiid. In the range of 7.55 to 16.05 mm total larval length, vulnerability to predation was highest for 13.3 and 13.7 mm larvae. Large hyperiids swam faster and covered a wider area during searching and were more effective predators than small ones. Predation seemed to be influenced by light, and its intensity was dependent on the duration of previous food deprivation of the hyperiid.This study was sponsored by the International Bureau of the Gesellschaft für Kernenergiever-wertung in Schiffbau und Schiffahrt in connection with the German Canadian agreement on scientific and technical cooperation. 相似文献
945.
The infratidal zonation of animals in a 35 m deep fjord-like South African estuary is described. The barnacle Balanus amphitrite Darwin and the bivalve Musculus virgiliae Barnard form the uppermost zone and extend to a depth of 9 m. The oyster Crassostrea margaritacea (Lam.) forms a zone between 1 and 3 m depth while the sponge Grantessa ramosa (Haeckel) occurs between 3 and 7 m. The tubiculous polychaete Mercierella enigmatica Fauvel is the only species found below 10 m, and attains a depth of 33 m. In the wet season (summer) the surface salinity dropped to 2 and temperatures rose to 24°C. In the dry season (winter) surface salinity rose to 24 and temperatures dropped to 16°C. Salinity and temperature of deep water (6 to 33 m) were more stable and varied only between 32.5 and 35 and between 19.6° and 20.5°C, respectively. In June, water below 12 m was 50 to 60% saturated with oxygen but this declined to less than 5% saturation in January. 相似文献
946.
Summary. Breeding burrows of Parastizopus armaticeps armaticeps, a fossorial desert tenebrionid beetle, are cleptoparasitised by the closely related Eremostibes opacus. Gas chromatographic analyses show a high congruity of the cuticular hydrocarbons of both species. We compare these hydrocarbon
patterns with those of four other Stizopina species and the Scaurini Herpiscius sommeri. In a bioassay, dummies treated with cuticular hydrocarbon extracts of E. opacus and the P. a. bifidus parasite E. bushmanicus were mostly ignored by P. a. armaticeps, whereas dummies with applied extracts of the remaining species were heavily attacked. We show that there is a correlation
between agonistic behaviour of P. a. armaticeps towards the intruder and the chemical similarity of the cuticular hydrocarbons of the two species. Furthermore, we produced
quantitatively modified hydrocarbon patterns of E. barbatus by changing the temperature at which this species was kept. The new 30 °C type was chemically similar to E. opacus, and was frequently ignored by P. a. armaticeps, whereas a reduction of the temperature to 20 °C only had minor effects on the hydrocarbon pattern. Furthermore, we show
that the addition of one single component, heptacosane, to the cuticular hydrocarbon extract of E. opacus alters the host’s reaction. We discuss the role of cuticular hydrocarbons for the recognition of this host-parasite system
and the relevance of quantitative characters in the hydrocarbon pattern for the discrimination of the host. 相似文献
947.
948.
949.
950.