全文获取类型
收费全文 | 671篇 |
免费 | 35篇 |
专业分类
706篇 |
出版年
2024年 | 4篇 |
2021年 | 11篇 |
2019年 | 4篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 13篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 23篇 |
2012年 | 41篇 |
2011年 | 25篇 |
2010年 | 31篇 |
2009年 | 17篇 |
2008年 | 39篇 |
2007年 | 38篇 |
2006年 | 34篇 |
2005年 | 20篇 |
2004年 | 29篇 |
2003年 | 24篇 |
2002年 | 26篇 |
2001年 | 9篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1977年 | 8篇 |
1965年 | 5篇 |
1937年 | 4篇 |
1936年 | 4篇 |
1935年 | 8篇 |
1932年 | 5篇 |
1931年 | 6篇 |
1930年 | 7篇 |
1929年 | 11篇 |
1897年 | 3篇 |
1896年 | 3篇 |
1892年 | 3篇 |
排序方式: 共有706条查询结果,搜索用时 15 毫秒
1.
2.
Curt Floericke 《Journal of Ornithology》1892,40(2):167-170
Ohne Zusammenfassung1887. 相似文献
3.
4.
Helena C. Kraemer Byron Alexander Cathy Clark Curt Busse David Riss 《Primates; journal of primatology》1977,18(4):825-833
A method is suggested to evaluate on an empirical basis sampling plans for the longitudinal study of primate behavior in those
very common situations in which the mathematical structure of behavior is unknown. The method is based on a randomization
procedure applied to a pilot sample of the behavior organized so that cost of implementation of a sampling plan can be evaluated
vis á vis the sampling error intrinsic to the plan. 相似文献
5.
6.
Anita Murray Salvatore Cerchio Robert McCauley Curt S. Jenner Yvette Razafindrakoto Douglas Coughran Shannon McKay Howard Rosenbaum 《Marine Mammal Science》2012,28(1):E41-E57
Comparing humpback whale song from different breeding assemblages can reveal similarities in song due to acoustically interacting males, and therefore indirectly test whether males from different breeding sites are mixing. Northern Hemisphere song comparisons illustrated that whales within ocean basins share similar songs and are subpopulations within a larger population, whereas whales in different ocean basins are isolated populations and therefore do not share songs. During the 2006 breeding season, recordings were collected in Madagascar and Western Australia, and were compared visually plus aurally. Both regions shared one theme, whereas each region had four and six private themes, respectively. This study had a substantially low number of shared themes. The co‐occurrence of one theme was interpreted as an indication of limited exchange between these breeding assemblages, and we speculate that limited song similarity is due to inter‐oceanic interactions. Male(s) from an Indian Ocean breeding group could be exposed to novel song when they geographically overlap, and acoustically interact, with males from a different ocean basin. Novel song could induce rapid temporal changes as new song content is incorporated, thereby minimizing song similarities between that breeding group and other Indian Ocean breeding groups that were not exposed to the novel song. 相似文献
7.
E M Teichert 《Acta microbiologica Polonica》1987,36(3):237-245
The interaction of the fungicide Dithane M-45 (active ingredient mancozeb), with Pseudomonas aeruginosa strain not sensitive to the compound, was studied. Pseudomonas aeruginosa produced a fungicidal compound inhibiting the growth of Fusarium oxysporum. Simultaneously Pseudomonas aeruginosa degraded the EBIS (ethyleneisothiocyaniane) formed from the spontaneous decomposition of the fungicide which is highly toxic for Fusarium oxysporum. When the fungicide was used as seed dressing together with the bacteria the inhibition of the fungus was reduced to the interaction of both fungicidal compounds. 相似文献
8.
Dellinger TA Youngman RR Laub CA Brewster CC Kuhar TP 《Journal of economic entomology》2006,99(4):1235-1244
Cultivars of glandular-haired alfalfa, Medicago sativa L., such as '54H69', are currently available and marketed as being resistant to potato leafhopper, Empoasca fabae (Harris) (Hemiptera: Cicadellidae). 54H69 and a standard, nonglandular-haired alfalfa 'Choice' were evaluated at two locations in Virginia over a 3-yr period. Dry matter yields and concentrations of crude protein and acid detergent fiber were compared at the first, second, and third harvests. Overall, the two cultivars produced similar dry matter yields of comparable forage quality in the absence of insecticides at both locations in each year. Untreated 54H69 did not produce greater dry matter yields than untreated Choice under either light or heavier potato leafhopper pest pressure. Concentrations of crude protein did not vary between the two cultivars at any harvest. Some differences in concentrations of acid detergent fiber were detected between cultivars, but these differences were not consistent among years, harvests, or between locations. Further comparisons between untreated 54H69 and treated Choice were made, but few significant differences were detected in dry matter yields or forage quality. An economic analysis for the study indicated that a grower planting 54H69 would realize less net revenue than a grower planting Choice, largely because of the seed premium for the glandular-haired cultivar and the evident need to treat 54H69 with insecticide for control of alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), and potato leafhopper. 相似文献
9.
Chromatin plays a fundamental role in eukaryotic genomic regulation, and the increasing awareness of the importance of epigenetic processes in human health and disease emphasizes the need for understanding the structure and function of the nucleosome. Recent advances in chromatin structural studies, including the first structures of nucleosomes containing the Widom 601 sequence and the structure of a chromatin protein-nucleosome assembly, have provided new insight into stretching of nucleosomal DNA, nucleosome positioning, binding of metal ions, drugs and therapeutic candidates to nucleosomes, and nucleosome recognition by nuclear proteins. These discoveries ensure promising future prospects for unravelling structural attributes of chromatin. 相似文献
10.
Curt Nilsson 《Hydrobiologia》1983,98(3):267-269
Two experimental groups of Culiseta bergrothi Edw. larvae were kept under laboratory conditions, but in water from the breeding locality. The ‘donors’ were fed on a suspension of charcoal powder and baker's yeast; the ‘receivers’ had access to the faecal pellets of the donors. After 1.5 hours the gut of almost all receivers was more or less filled with charcoal particles. The possible consequences of the added yeast suspension to food choice and feeding behaviour are discussed. 相似文献