全文获取类型
收费全文 | 830篇 |
免费 | 28篇 |
国内免费 | 2篇 |
专业分类
林业 | 69篇 |
农学 | 23篇 |
基础科学 | 4篇 |
169篇 | |
综合类 | 107篇 |
农作物 | 86篇 |
水产渔业 | 51篇 |
畜牧兽医 | 276篇 |
园艺 | 18篇 |
植物保护 | 57篇 |
出版年
2022年 | 11篇 |
2021年 | 19篇 |
2020年 | 22篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 21篇 |
2013年 | 35篇 |
2012年 | 34篇 |
2011年 | 52篇 |
2010年 | 25篇 |
2009年 | 25篇 |
2008年 | 49篇 |
2007年 | 42篇 |
2006年 | 25篇 |
2005年 | 48篇 |
2004年 | 47篇 |
2003年 | 45篇 |
2002年 | 32篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1980年 | 4篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1969年 | 4篇 |
1966年 | 4篇 |
1961年 | 4篇 |
1960年 | 4篇 |
1955年 | 4篇 |
排序方式: 共有860条查询结果,搜索用时 15 毫秒
1.
Matthew M. Nelson Ben D. Mooney Peter D. Nichols Charles E Phleger Greg G. Smith Piers Hart Arthur J. Ritar 《Journal of the World Aquaculture Society》2002,33(2):146-157
The lipid class and fatty acid (FA) composition of juvenile Artemia fed continuously on four diets—the microalga Tetraselmis suecica , a mix of oat bran-wheat germ-lecithin (OWL), OwL-eicosapentaenoic acid (EPA), and OWL-EPA-arachidonic acid (AA)—were examined over a 9-d experiment in an attempt to approximate the FA profile of phyllosoma larvae of wild southern rock lobster Jasus edwardrii . The main difference in lipid class composition of Artemia fed the four diets was the relative level of polar lipid (PL) and triacylglycerol (TAG). By day 9, the algal-fed Artemia were highest in PL (95% of total lipid) and lowest in TAG (2%), whereas the remaining diets resulted in Artemia with 16–30% PL and 41–82% TAG. After 2 d, the relative FA composition of all Artemia treatments closely reflected those of the diets, with no marked change after further feeding (to day 9). In terms of the content of essential polyunsaturated fatty acids (PUFA), by day 5 Artemia fed: 1) with the algal diet contained 7 mg/g FA dry mass (0.3% DHA, 6.3% EPA, 3.4% AA of total FA); 2) with the OWL diet contained 3 mg/g (0.3% DHA, 0.9% EPA, 0.7% AA); 3) with the OWL-EPA diet contained 55 mg/g (6.2% DHA, 11.6% EPA, 1.1% AA); and 4) with the OWL-EPA-AA contained 83 mg/g (3.8% DHA, 7.5% EPA, 17.4% AA). The PUFA profiles of Artemia using the OWL-oil diets were similar to wild rock lobster phyllmmata, although levels of doco-sahexaenoic acid (DHA) were lower (10% DHA) than in J. edwardsii larvae. On the basis of PUFA composition data alone, the results suggest the suitability of the OWL-oil mixed diets for consideration for feeding to Artemia used in the culture of southern rock lobster larvae, particularly if the level of DHA can be further enhanced. 相似文献
2.
Malignant catarrhal fever was diagnosed in a newly imported swamp buffalo calf. This disease is prevalent in deer and cattle in New Zealand and causes sporadic losses in these species. The disease is recognised as a problem in buffaloes overseas and this paper records the first case in a swamp buffalo in New Zealand. 相似文献
3.
4.
Elliott R Jacobson Darryl Heard Arthur Andersen 《Journal of veterinary diagnostic investigation》2004,16(2):153-154
Tissues were evaluated from emerald tree boas, Corallus caninus, from a collection in which chlamydiosis was diagnosed. To determine the strain of chlamydia infecting these snakes, tissue samples from 5 frozen snakes were tested by a quantitative TaqMan polymerase chain reaction (PCR) test and a PCR sequence analysis test. Of the 22 samples tested, 9 were categorized as either positive or weakly positive with the TaqMan test, and 6 yielded an amplicon using a serial PCR test that amplified a portion of the 23S ribosomal RNA gene. A PCR product suitable for sequencing was obtained from the heart of one of the snakes. Sequence analysis showed that the snake had been infected with Chlamydophila pneumoniae. These findings show that C. pneumoniae can infect emerald tree boas, broadening the range of reptiles known to be infected by this primarily human pathogen. 相似文献
5.
6.
7.
8.
Kouakou Laurent Kouakou Irié Arsène Zoro Bi Yao Georges Abessika Tanoh Hilaire Kouakou Jean-Pierre Baudoin 《Scientia Horticulturae》2009
To develop efficient seedling production methods for Laccosperma secundiflorum and Eremospatha macrocarpa, a study was conducted to examine regeneration using offsets combined with several physical and chemical treatments of seeds. Offsets categorized into small, medium and large diameters, were planted in three conditions: shaded and open nursery, and greenhouse. We tested sucker from E. macrocarpa, and sucker and rhizome from L. secundiflorum. For both species, high viability percentage (ranging from 55% to 100%) were observed for small and medium suckers planted in shaded nursery and greenhouse, against less than 49% for sucker planted in open nursery. The mean seedling emergence times were estimated to 84, 77 and 75 days after planting (DAP) for small, medium and large sucker of L. secundiflorum, respectively under open nursery condition, and 76, 75, 95 DAP for small, medium and large suckers of the same species, respectively in shaded condition. Greenhouse has a significant positive effect on E. macrocarpa seedlings emergence time. For this species, the mean seedling emergence times were estimated to 43 DAP for small sucker and 76, 93 DAP for medium and large suckers. No seedling was obtained from rhizome planted in all the growing conditions tested. Concerning seed dormancy breaking, germination percentages and rates were determined for 13 treatments. The best treatments were pre-soaking unscarified seeds for 4 days in 1.01 g l−1 and 0.10 g l−1 KNO3, with 79% and 68% of germination, respectively and in 3.46 × 10−3 g l−1 GA3 for 68% of germination. These methods are suggested to improve germination of L. secundiflorum seeds. Successful and recommended methods for E. macrocarpa are pre-soaking scarified seeds in 3.46 × 10−3 g l−1 and 3.46 × 10−4 g l−1 GA3, 96% and 94% of germination, respectively. Dormancy, probably a combination of mechanical and chemical dormancy, is present in the two species. 相似文献
9.
We examined the foraging behaviour and habitat use of two species of small Australian mammal (Antechinus flavipes and Sminthopsis murina) in response to predation risk in remnant eucalypt woodland. Predation risk was manipulated by providing refuge in the form of ground level wire netting to reduce risks from avian and mammalian predators. Giving-up-densities (GUD) using artificial food trays (20 mealworms in 1.5 l vermiculite) quantified the foraging behaviour in response to predation risk, by measuring the quitting harvest rate. Both A. flavipes and S. murina had lower GUDs (number of mealworms remaining) under the netting than in the open, most likely because these areas have lower predation risk. Animals also made greater visits to tracking tunnels under the netting compared to in the open. Tracking animal movements using fluorescent pigments also revealed preference for natural microhabitats that were structurally complex with animals moving most where logs and rock crevices were present. These results suggest that small mammals may use habitat structure to reduce their risks of predation. If future studies are able to demonstrate commensurate population-level responses, manipulation of habitat may be a useful management option to complement the direct control of exotic predators such as foxes and feral cats. 相似文献
10.
The potential of mini-ridging for controlling intrarow weeds: estimating minimum lethal burial depth
Charles N. Merfield Jacquelyn R. Bennett Nadine A. Berry Arthur Bluon Dean M. O’Connell Simon Hodge 《Weed Research》2020,60(5):353-362
Weed management using synthetic herbicides is undergoing a global decline, necessitating a re-evaluation of existing control measures and the development of novel weed management tools. ‘Mini-ridging’ is a non-discriminatory, physical weeding method that functions by burying weeds in the intrarow with a laterally shifted ridge of soil. In glasshouse trials using potted plants, we found that plant recovery after soil application was influenced by plant size, which in turn was influenced by plant species, developmental stage and/or age. The likelihood of plant recovery after soil application was negatively related to the depth of soil applied: very few plants survived total coverage by soil but, conversely, survival could be substantial if some parts of the plants were not covered. The results suggest that burial under a depth of 6 cm of soil would eliminate most plants regardless of species or growth stage. Larger plants would require the application of a greater total depth of soil to achieve this 6 cm of soil cover, and weed management would, therefore, tend to be more successful and more practical if weeds were targeted when still small. This research demonstrates the potential of plant burial as a simple and reliable means of non-chemical weed management, and re-emphasises that, for weed control to be effective, the applied soil layer must cover the whole plant. 相似文献