全文获取类型
| 收费全文 | 319篇 |
| 免费 | 32篇 |
专业分类
| 林业 | 18篇 |
| 农学 | 3篇 |
| 基础科学 | 1篇 |
| 58篇 | |
| 综合类 | 34篇 |
| 农作物 | 16篇 |
| 水产渔业 | 29篇 |
| 畜牧兽医 | 167篇 |
| 园艺 | 8篇 |
| 植物保护 | 17篇 |
出版年
| 2024年 | 3篇 |
| 2023年 | 14篇 |
| 2022年 | 2篇 |
| 2021年 | 23篇 |
| 2020年 | 20篇 |
| 2019年 | 29篇 |
| 2018年 | 16篇 |
| 2017年 | 15篇 |
| 2016年 | 18篇 |
| 2015年 | 14篇 |
| 2014年 | 12篇 |
| 2013年 | 15篇 |
| 2012年 | 21篇 |
| 2011年 | 16篇 |
| 2010年 | 17篇 |
| 2009年 | 13篇 |
| 2008年 | 20篇 |
| 2007年 | 14篇 |
| 2006年 | 19篇 |
| 2005年 | 15篇 |
| 2004年 | 6篇 |
| 2003年 | 8篇 |
| 2002年 | 15篇 |
| 2001年 | 1篇 |
| 1999年 | 1篇 |
| 1994年 | 1篇 |
| 1991年 | 1篇 |
| 1990年 | 1篇 |
| 1986年 | 1篇 |
排序方式： 共有351条查询结果，搜索用时 250 毫秒
61.
Pesticides can modify invertebrate movement and feeding behaviour which could reduce predation in agroecosystems. Previous assays have exposed the spider Pardosa amentata (Clerck) to the synthetic pyrethroid cypermethrin and monitored prey items consumed in small containers (requiring very little movement to capture prey). The current study used larger arenas containing artificial 'vegetation' (a plastic analogue) to encourage spiders to hunt and capture prey. The period 24 h after exposure produced greatest variability in prey item consumption between treatments and was used to examine treatment effects. At this time, cypermethrin reduced prey consumption rates but these effects did not persist. Findings did not suggest that the presence of artificial vegetation in arenas modified prey consumption rates, which was consistent for individuals treated with cypermethrin and a control group. This is despite the majority of pesticide-treated individuals exhibiting both ataxia and paralysis of the hind legs (these effects persisting for a maximum of 3 and 6 days respectively). These findings were consistent for both sexes. Spider longevity under starvation conditions was not significantly reduced by cypermethrin exposure but overall females survived longer than males. The findings are discussed in the context of the arenas used and the ecology of this common predator. 相似文献
62.
63.
Emma L. Houck Eli B. Cohen Mandy Womble Gregory A. Lewbart Olivia A. Petritz 《Veterinary radiology & ultrasound》2019,60(5):473-484
Gastrointestinal disorders are an important cause of morbidity in box turtles (Terrapene carolina Carolina), however published information is currently lacking on the normal radiographic anatomy, transit, and emptying times of the gastrointestinal tract. A total of 15 healthy box turtles were recruited for this prospective, anatomic, reference interval study. Three‐view radiographic series (vertical beam dorsoventral, horizontal beam latero‐lateral, and horizontal beam rostrocaudal views) were acquired prior to contrast administration, and following contrast administration at 0, 20, 40, 60, and 90 min, 2, 4, 8, 12, and 24 h post administration, and every 24 h thereafter until all contrast was eliminated (15 mL/kg barium sulfate diluted to 30% weight per volume was administered via orogastric gavage). Vertical beam dorsoventral and horizontal beam latero‐lateral views were of excellent quality to identify gastrointestinal structures. The horizontal beam rostrocaudal view immediately postcontrast administration provided gastric and pyloric identification but had lesser diagnostic use at later time points due to anatomical superimposition. The gastrointestinal tract was composed of a tubular stomach, a pyloric sphincter near midline, a duodenum with a cranial flexure in the right cranial coelomic cavity, small intestines within the right coelom, a small cecal bulb, and a transverse and descending colon. Contrast media entered the large intestine by 24 h in all turtles, and a pyloro‐colic indentation was noted at the proximal descending colon. The large intestinal emptying was highly variable due to the interindividual variability of contrast sequestration within the cecal bulb. Findings from the current study serve as a reference on the gastrointestinal anatomy, transit, and emptying times in healthy eastern box turtles; and introduce a novel, horizontal beam, rostrocaudal view for gastrointestinal contrast studies in chelonians. 相似文献
64.
65.
Context
An increasing number of studies have investigated the impact of environmental heterogeneity on faunal assemblages when measured at multiple spatial scales. Few studies, however, have considered how the effects of heterogeneity on fauna vary with the spatial scale at which the response variable is characterised.Objectives
We investigated the relationship between landscape properties in a region characterised by diverse fire mosaics, and the structure and composition of avian assemblages measured at both the site- (1 ha) and landscape-scale (100 ha).Methods
We surveyed birds and calculated spatial landscape properties in sub-tropical woodlands of central Queensland, Australia.Results
Environmental heterogeneity, as measured by topographic complexity, was consistently important for bird species richness and composition. However, the explanatory power of topographic complexity varied depending on the spatial scale and the component of diversity under investigation. We found different correlates of richness within particular foraging guilds depending on the scale at which richness was measured. Extent of long-unburnt habitat (>10 years since fire) was the most important variable for the landscape-scale richness of frugivores, insectivores and canopy feeders, whereas environmental heterogeneity in the surrounding landscape was more important for site-scale richness of these foraging guilds.Conclusions
The response of species richness to landscape characteristics varies among scales, and among components of diversity. Thus, depending on the scale at which a biodiversity conservation goal is conceptualised—maximising richness at a site, or across a landscape—different landscape management approaches may be preferred.66.
67.
Patrick J Pollock Ronan Doyle Emma Tobin Kate Davison John Bainbridge 《Journal of zoo and wildlife medicine》2008,39(3):476-479
A 9-yr-old female Bornean orangutan (Pongo pygmaeus pygmaeus) presented with a 48-hr history of depression, lethargy, anorexia, and mucoid discharge from the rectum. Clinical, radiographic, and ultrasonographic examination demonstrated the presence of multiple distended loops of intestine, intestinal adhesions, and free gas within the abdomen. During exploratory laparotomy, fibrinopurulent diffuse peritonitis as a result of a ruptured intrapelvic abscess with associated large bowel adhesions was evident. The abdomen was thoroughly lavaged, necrotic debris and abscess wall removed, and fibrinous adhesions disrupted. The orangutan was kept sedated for 48 hr to allow for intensive care. Six months later, when the orangutan presented with similar clinical signs, ultrasonographic examination demonstrated the presence of a pelvic abscess. The previous procedure was repeated with the addition of a hysterectomy. This report is the first documentation of long-term management following surgical intervention for internal abdominal abscessation and septic peritonitis in a great ape. 相似文献
68.
69.
70.
Juni Rosann Engelien Johanssen Kristin Marie Sørheim Turid Strøm Emma Ida Brunberg 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2018,68(2):103-111
The aim of this project was to compare the hygienic quality of the bedding, as well as the parasitic load, cleanliness and lying behaviour in heifers kept on either straw or wood chip deep bedding. Fourteen heifers kept in two pens were housed on straw or wood chip bedding for 43 days, after which the bedding material was switched for 43 additional days. Significantly more mould was found in wood chip than in straw and there was a tendency towards less yeast in wood chip. The heifers had a low faecal parasitic load. The results indicate that the wood chip treatment resulted in somewhat cleaner animals. The heifers had a significantly longer total lying time when kept on straw. In conclusion, wood chip deep bedding could be an option as bedding material, but the impact on hygiene of bedding material and lying behaviour needs to be further investigated. 相似文献