全文获取类型
收费全文 | 263篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
安全科学 | 1篇 |
废物处理 | 3篇 |
环保管理 | 11篇 |
综合类 | 152篇 |
基础理论 | 36篇 |
污染及防治 | 45篇 |
评价与监测 | 12篇 |
社会与环境 | 5篇 |
出版年
2017年 | 3篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2011年 | 3篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 5篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1989年 | 3篇 |
1973年 | 3篇 |
1965年 | 6篇 |
1964年 | 4篇 |
1962年 | 2篇 |
1961年 | 8篇 |
1960年 | 3篇 |
1959年 | 4篇 |
1958年 | 2篇 |
1957年 | 7篇 |
1956年 | 2篇 |
1955年 | 8篇 |
1954年 | 3篇 |
1952年 | 3篇 |
1951年 | 3篇 |
1950年 | 3篇 |
1948年 | 2篇 |
1944年 | 2篇 |
1943年 | 2篇 |
1941年 | 4篇 |
1940年 | 4篇 |
1939年 | 7篇 |
1938年 | 3篇 |
1937年 | 2篇 |
1936年 | 2篇 |
1935年 | 4篇 |
1934年 | 2篇 |
1931年 | 3篇 |
1930年 | 5篇 |
1929年 | 2篇 |
1922年 | 5篇 |
1919年 | 2篇 |
1914年 | 2篇 |
排序方式: 共有265条查询结果,搜索用时 171 毫秒
111.
Bernd Eiben Susanne Hansen Jutta Knipping Regina Massenberg Richard Goebel Wilhelm Hammans 《黑龙江环境通报》1989,9(5):365-367
Chorionic villus samples from a healthy pregnant female were obtained for first-trimester prenatal diagnosis. A translocation trisomy 21 was diagnosed. A consecutive amniocentesis revealed a normal male karyotype. At term a healthy boy was born. Cytogenetic analysis from cord blood showed a regular karyotype of 46,XY, whereas in term placenta a pathological karyotype of 47,XY,+mar was found. 相似文献
112.
113.
114.
Potential parasitoid attractants,volatile
composition throughout a bark beetle attack 总被引:3,自引:0,他引:3
Several hymenopteran parasitoids prey on mature bark beetle larvae (Scolytidae), concealed under the bark of conifers. According to previous results, certain oxygenated monoterpenes are crucial in host location. However, synthetic baits tested in laboratory bioassays are not quite as attractive to the parasitoids as the natural volatile bouquet from conifers containing susceptible bark beetle larvae. The aim of the current study was to identify the "missing components" in previously tested synthetic baits. Volatiles were sampled throughout bark beetle attacks (Ips typographus) on Norway spruce logs (Picea abies), and analyzed (qualitatively and quantitatively) by coupled gas chromatography-mass spectrometry (GC-MS). In addition, a pilot test was done employing the relatively new technique, fast GC-surface acoustic wave detector (SAW), zNoseTM, described in the methods. Quantitative differences in volatile composition were found between infested and uninfested logs, and between different stages of the bark beetle attack. In addition, the volatile composition of logs with or without mature bark beetle larvae (susceptible to parasitism) was compared, isolating odor differences at this most suitable host stage. In general, the quantity of monoterpenes (the predominant phytochemical volatiles in conifers) was found to decrease with time after initial infestation. In contrast, certain oxygenated monoterpenes and benzenoid compounds increased as susceptible bark beetle larvae developed, which therefore could be candidates for improving parasitoid baits. To the best of our knowledge, this is the first report on long-term dynamics of the volatile composition of bark beetle infested P. abies. The results should be interpreted in the light of previous electrophysiological and behavioral investigations of larval parasitoids, and present a number of compounds that could improve synthetic parasitoid baits. 相似文献
115.
116.
Janna Peters Jasmin Renz Justus van Beusekom Maarten Boersma Wilhelm Hagen 《Marine Biology》2006,149(6):1417-1429
Seasonal lipid dynamics of the copepod Pseudocalanus acuspes were studied in the Bornholm Basin (Central Baltic Sea) on a monthly basis from March 2002 until March 2003 and were interpreted in light of life cycle strategies and diet selection. The individual total lipid content of females ranged from 0.9 to 1.8 μg, with relative wax ester content reaching a significant maximum in May (44% of total lipids) and minimum (17% of total lipids) in April and November. Significant changes in size, lipid content, lipid classes and fatty acid composition of structural as well as storage lipids suggested five characteristic seasonal phases that were induced by different feeding histories and environmental conditions. Storage lipids were characterized by 18:1(n−9) as major component, which ranged between 44% of total fatty acids in June and 23% in February. The strong coherence between 18:1(n−9) in the seston lipids and the occurrence of ciliates emphasized the importance of ciliates in the diet of P. acuspes. As indicated by changes in the amounts of fatty acid markers, other food sources varied over the year, suggesting an opportunistic feeding behavior. The spring period was characterized by an increase in typical diatom and dinoflagellate markers, whereas other sources, potentially cyanobacteria, became more important during summer. The life cycle strategy is discussed with respect to extant adaptations to high latitudinal habitats. 相似文献
117.
118.
119.
120.