全文获取类型
收费全文 | 260篇 |
免费 | 19篇 |
专业分类
林业 | 3篇 |
农学 | 3篇 |
基础科学 | 2篇 |
32篇 | |
综合类 | 33篇 |
农作物 | 8篇 |
水产渔业 | 15篇 |
畜牧兽医 | 168篇 |
园艺 | 6篇 |
植物保护 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 7篇 |
2011年 | 10篇 |
2010年 | 16篇 |
2009年 | 22篇 |
2008年 | 15篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 12篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1974年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有279条查询结果,搜索用时 31 毫秒
81.
82.
Plasma lysozyme levels in sheatfish Silurus glanis (L.) subjected to stress and experimental infection with Edwardsiella tarda 总被引:2,自引:0,他引:2
Two experiments were conducted to assess plasma lysozyme levels, leucocrit and haematocrit in juvenile sheatfish (90–140 g) under experimentally induced stress and infection. Stress was provoked by random modification of environmental light for 15 min, 16 times a day with a halogen lamp (500 W) and by holding fish in a net for 3 min twice a day. In the first trial, repeated measuring of marked sheatfish showed a progressive significant decrease in plasma lysozyme level, a significant increase in leucocrit and a significant decrease in haematocrit. After a rest period of 1 week, only the leucocrit value was back to the prestress value. In the second trial, light‐induced stress did not lead to any variation in lysozyme, leucocrit or haematocrit values. However, after intraperitoneal injection of Edwardsiella tarda (7 × 108 cfu), a strong increase in plasmatic lysozyme in both stressed and unstressed groups of sheatfish was observed. The increase was significant vs. prechallenge levels 3 and 6 days after contamination, but no significant difference was detected between stressed and unstressed fish, despite the strongest stress (light+handling stress) applied to the fish at the beginning of contamination. Decreases in haematocrit values were observed in both groups of fish. A clear increase in leucocrit appeared in unstressed fish, whereas stressed fish showed a significant decrease in leucocrit values. Condition factor was significantly decreased by all kinds of stress. There were no difference in mortality between stressed and unstressed groups. 相似文献
83.
84.
Stable carbon and nitrogen isotope ratios ( 13C/ 12 C and 15N/14 N) of in situ dominant primary producers and consumers were investigated to assess the impact on a natural ecosystem of a land-based fish farm along the south-western coast of Sicily (Italy). The putatively impacted area close to the farm along outfall was compared with other locations at increasing distances from the outfall. Carbon and mainly nitrogen stable isotopes revealed evidence of widespread aquaculture waste in the study site: benthic organisms collected in the impacted area showed more enriched 15N signatures than those at greater distances from the outfall, suggesting a large contribution of aquaculture waste to the food web. By contrast, both nekton-benthic and pelagic organisms seemed to be less influenced by discharge, probably due to their mobile habit. 相似文献
85.
Caruso F Tanski J Villegas-Estrada A Rossi M 《Journal of agricultural and food chemistry》2004,52(24):7279-7285
From the experimental crystal structure and ab initio calculations on resveratrol and its derivatives, structural features of mechanistic importance are described. The molecular structure reveals the relative coplanarity of the trans-stilbene skeleton, and the molecular packing in the solid state shows an extensive hydrogen bond network that elucidates the flip-flop motion of the three hydroxyl groups that alternately form and break H bonds with each of the neighboring phenolic oxygens. The dynamic behavior provoked by the alternation of hydrogen bond formation and breaking can result in the ready mobility of up to three hydrogen atoms per resveratrol molecule that can be transferred to reactive oxidants that are rich in electron density. In addition, theoretical studies confirm the planarity of resveratrol as well as for half of the molecule of a condensation dimeric derivative of resveratrol, trans-sigma-viniferin. Furthermore, these studies show the p-4'-OH group to be more acidic compared to the other two m-OH groups. These features correlate with the biological activity of resveratrol as an antioxidant and support earlier studies showing H-atom transfer to be the dominant mechanism by which phenolic antioxidants intercept free radicals. 相似文献
86.
不同利用方式下草地土壤微生物及土壤呼吸特性 总被引:7,自引:0,他引:7
通过对呼伦贝尔羊草(Leymus chinensis)草甸草原土壤呼吸特性及土壤微生物的测定,研究了3种不同利用方式(围封、放牧和刈割)对天然草地土壤呼吸特性及土壤微生物的影响,为草甸草原土壤呼吸研究提供基础理论依据。结果表明:不同利用方式下土壤呼吸速率、土壤微生物量碳含量与土壤酶活性(除脲酶)均表现为草地围封比放牧和刈割呼吸速率高(含量高、活性强);土壤微生物量氮含量、脲酶活性和微生物数量表现为草地放牧和刈割比围封的含量高(活性强、数量多);土壤微生物量碳、氮含量、土壤酶活性(除脲酶)和土壤微生物数量均以表层(0~10cm)最高(活性最强、数量最多),随着土层深度增加而降低(活性下降、数量减少)。土壤呼吸速率与微生物量碳、土壤酶活性(除过氧化氢酶)成正相关,与微生物量氮、过氧化氢酶和微生物数量成负相关,其中只与微生物量氮相关性显著,而其余之间均不显著。 相似文献
87.
88.
GJ EAMENS PD KIRKLAND MJ TURNER JA GARDNER† MP WHITE‡ CL HORNITZKY 《Australian veterinary journal》1988,65(4):120-123
Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida. 相似文献
89.
90.