全文获取类型
收费全文 | 933篇 |
免费 | 12篇 |
国内免费 | 6篇 |
专业分类
林业 | 18篇 |
农学 | 13篇 |
基础科学 | 28篇 |
116篇 | |
综合类 | 420篇 |
农作物 | 6篇 |
水产渔业 | 3篇 |
畜牧兽医 | 314篇 |
园艺 | 14篇 |
植物保护 | 19篇 |
出版年
2022年 | 6篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 14篇 |
2012年 | 51篇 |
2011年 | 52篇 |
2010年 | 23篇 |
2009年 | 16篇 |
2008年 | 52篇 |
2007年 | 50篇 |
2006年 | 40篇 |
2005年 | 50篇 |
2004年 | 31篇 |
2003年 | 31篇 |
2002年 | 36篇 |
2001年 | 25篇 |
2000年 | 20篇 |
1999年 | 15篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1982年 | 7篇 |
1971年 | 5篇 |
1966年 | 7篇 |
1963年 | 13篇 |
1960年 | 7篇 |
1959年 | 10篇 |
1958年 | 11篇 |
1957年 | 6篇 |
1956年 | 10篇 |
1955年 | 5篇 |
1954年 | 9篇 |
1953年 | 13篇 |
1948年 | 6篇 |
1945年 | 9篇 |
1943年 | 5篇 |
1939年 | 7篇 |
1938年 | 5篇 |
1936年 | 5篇 |
1933年 | 5篇 |
1932年 | 7篇 |
1931年 | 5篇 |
1928年 | 5篇 |
1926年 | 5篇 |
1893年 | 6篇 |
1881年 | 11篇 |
1880年 | 7篇 |
排序方式: 共有951条查询结果,搜索用时 46 毫秒
1.
2.
4.
5.
6.
7.
The fungal pathogen Verticillium dabliae was less likely to cause symptoms of verticillium wilt on cotton seedlings that had been previously exposed to spider mites than on unexposed cotton seedlings. Conversely, populations of the spider mite Tetranychus urticae grew less rapidly on seedlings that had been inoculated with V. dabliae than on uninoculated controls. Changes caused by pathogen or herbivore attack reduced the suitability of the host plant to a diversity of organisms. This result suggests that highly unrelated organisms that share a host plant may interact strongly. 相似文献
8.
Roof WC 《Science (New York, N.Y.)》1984,223(4637):691
9.
Abstract Sir, - Andrews'((2)) checklist of helminth parasites of wild ruminants in New Zealand recorded the presence of 10 species of gastrointestinal nematodes in chamois (Rupicapra rupicapra rupicapra L.) from "Central South Island". In October 1978 we examined 28 freshly-shot chamois cadavers from the Harper-Avoca watershed in the headwaters of the Rakaia River. Six of the nematode species reported by Andrews were found again; viz. Ostertagia ostertagi, O. circumcincta, O. trifurcata, Nematodirus filicollis, Oesophagostomum venulosum and Trichuris ovis. The 4 species found by Andrews that were not recovered by us from the animals we examined were: Trichostrongylus axei, T. vitrinus, Spiculotragia spiculoptera and S. asymmetrica. On the other hand we found 4 helminths not encountered by Andrews: 3 nematodes: Nematodirus spathiger (Railliet, 1896), N. abnormalis (May, 1920), and Chabertia ovina (Fabricius, 1794), and 7 specimens of the cestode Moniezia expansa (Rud., 1805). Nematodirus spathiger was the most commonly encountered Nematodirus species, but generally the numbers of all 3 species encountered were low as might be expected in a sample of adult and almost year-old animals. It is probable that most of the adults had acquired some measure of immunity((3)), and the most susceptible group, the kids, would not be born until late November. Because peptic digestion was not used to recover juveniles from the intestinal submucosa, only small numbers of adults were obtained. 相似文献
10.
Embryo transfer: a discussion on its potential for infectious disease control based on a review of studies on infection of gametes and early embryos by various agents 总被引:1,自引:1,他引:0 下载免费PDF全文
Eaglesome MD Hare WC Singh EL 《The Canadian veterinary journal. La revue veterinaire canadienne》1980,21(4):106-112
Studies on laboratory animals have shown that viruses vary as to whether or not they are transmissible by the gametes or are capable of passing through the zona pellucida and infecting the embryo.
Methods of studying early embryos for the presence of infectious agents include electron microscopy, immunocytochemistry and cell cultivation.
Determination that early bovine embryos do not become infected by certain agents might allow for easing of restrictions in the current import and export regulations for cattle embryos.
Embryo transfer could be used as a means of controlling or eliminating disease in a herd or flock if the causal agent does not infect the early embryo via the gametes or by penetrating the zona pellucida.
相似文献