首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   121篇
  免费   4篇
林业   8篇
农学   7篇
  40篇
综合类   5篇
农作物   13篇
水产渔业   2篇
畜牧兽医   33篇
园艺   4篇
植物保护   13篇
  2023年   3篇
  2022年   2篇
  2021年   5篇
  2020年   4篇
  2019年   10篇
  2018年   2篇
  2017年   5篇
  2016年   3篇
  2015年   2篇
  2014年   4篇
  2013年   4篇
  2012年   11篇
  2011年   19篇
  2010年   7篇
  2009年   3篇
  2008年   7篇
  2007年   2篇
  2006年   2篇
  2005年   7篇
  2004年   7篇
  2003年   3篇
  2002年   5篇
  2000年   3篇
  1999年   1篇
  1991年   2篇
  1990年   1篇
  1984年   1篇
排序方式: 共有125条查询结果,搜索用时 140 毫秒
51.
Canine aggressive behaviour is one of the most common problems being reported by dog owners. However, the biochemical basis of this phenomenon remains unclear. In humans, alterations in omega-3 plasma polyunsatured fatty acids and elevated omega6/omega-3 ratio have been linked to behavioural alterations, including aggression. Thus far, however, the relationship between plasma polyunsatured fatty acid status and aggression has not been investigated in the dog. In the present study we sought to investigate whether polyunsatured fatty acid status could be altered in plasma of pathologically aggressive Canis familiaris. Eighteen adult male German Shepherd dogs, aged 4.9 ± 0.9 years, showing no clinical signs but aggression, were investigated. Eighteen healthy male dogs, aged 4.8 ± 0.7 years, with a negative history of behavioural and neurological disorders served as controls. Baseline fasting plasma polyunsatured fatty acid composition was determined by gas chromatography. Compared to normal dogs, aggressive dogs showed lower docosahexaenoic acid (22:6 n-3) concentrations and a higher omega6/omega-3 ratio. In addition, they showed reduced cholesterol and bilirubin concentrations compared to their normally behaving counterparts. Altogether, our results suggest that low omega-3 fatty acids may adversely impact behaviour in dogs, resulting in greater propensity to aggression. However, given the cross-sectional design of our study, we cannot claim any causal relationship between the presence of alterations in fatty acid status and canine aggressiveness. Whether omega-3 fatty acids supplementation may be useful to reduce aggressive behaviour in the dog deserves further investigation.  相似文献   
52.
53.
54.
Glycerol is one of the substrates used for glycogen production by the chicken embryo, which is the predominant energy source during the last days of incubation and during hatching. The objective of the present study was to evaluate the in ovo feeding (IOF) of glycerol in the light and heavy broiler eggs derived from breeders of two different ages. Two experiments, with 672 eggs each, were carried out. The only difference between the experiments was breeder age: 32 weeks old in Exp. I and 60 weeks old in Exp. II. A completely randomized experimental design in a 3 × 2 factorial arrangement was applied. Treatments consisted of three glycerol IOF doses (0, 6, or 12 mg/ml) and two egg weights (light or heavy). Incubation parameters, glycogen reserves and live performance parameters (1–7 days of age) were evaluated. Hatch of fertile eggs, embryo mortality after IOF and the number of early‐hatching chicks were not affected by the treatments in both experiments. Hatchlings from heavy eggs (68.03 ± 0.64 g) laid by young breeders and receiving 6 mg glycerol/ml showed higher liver glycogen levels than those injected with 0 or 12 mg/ml. Glycerol IOF of embryos from young breeders increased feed intake and weight gain at 7 days of age, independently of egg weight. However, different glycerol dosages had no effect on the performance of the progeny of 60‐week‐old breeders. These results show that glycerol may be used as an IOF ingredient without affecting incubation parameters. The chickens from young breeders had greater glycogen deposition with inoculation of 6 mg/ml of glycerol and better performance with glycerol administration. However, glycerol IOF did not improve the performance of the progeny of 60‐week‐old breeders. Therefore, glycogen IOF may be recommended for eggs laid by young breeders.  相似文献   
55.
56.
The aims of this work were to re-evaluate the moments of resistance (MoRs) of the vertebral column proposed by Slijper (1946) in the dog and to study the relationship between the MoRs and the frequency distribution of vertebral traumas in the same species. The spine (C2-L7) of four dogs was measured to obtain MoRs and subsequently scanned with a dual-energy X-ray absorptiometer (DXA). These findings were then analysed retrospectively the frequency distribution of canine vertebral fractures and luxations, diagnosed radiographically at a referral practice. The highest percentage of vertebral injuries affected the T9-L7 tract. This study confirmed that this segment was characterized by a rising trend of the MoR curves and presumably bore the major bending forces. The significant correlation between T9-L1 MoRs and DXA values supports the Slijper’s hypothesis suggesting the posterior thoracic region as the weakest segment of the body-axis.  相似文献   
57.
Collagen has become a key-molecule in cell culture studies and in the tissue engineering field. Industrially, the principal sources of collagen are calf skin and bones which, however, could be associated to risks of serious disease transmission. In fact, collagen derived from alternative and riskless sources is required, and marine organisms are among the safest and recently exploited ones. Sea urchins possess a circular area of soft tissue surrounding the mouth, the peristomial membrane (PM), mainly composed by mammalian-like collagen. The PM of the edible sea urchin Paracentrotus lividus therefore represents a potential unexploited collagen source, easily obtainable as a food industry waste product. Our results demonstrate that it is possible to extract native collagen fibrils from the PM and produce suitable substrates for in vitro system. The obtained matrices appear as a homogeneous fibrillar network (mean fibril diameter 30–400 nm and mesh < 2 μm) and display remarkable mechanical properties in term of stiffness (146 ± 48 MPa) and viscosity (60.98 ± 52.07 GPa·s). In vitro tests with horse pbMSC show a good biocompatibility in terms of overall cell growth. The obtained results indicate that the sea urchin P. lividus can be a valuable low-cost collagen source for mechanically resistant biomedical devices.  相似文献   
58.
59.
The simultaneous determination of 19 phenolic compounds was performed directly in wort and beer by a combination of reverse-phase high-performance liquid chromatography coupled with coulometric array detection. Chromatographic separation was achieved with an appropriate gradient of flow and a binary solvent based on phosphate buffer, methanol, and acetonitrile in a 45-min run. Eight serial coulometric detectors were used for on-line generation of voltammetric data to resolve coeluting compounds. The method was reliable and sensitive, the regression coefficient of standard calibration curves is 0.972 < or = r < or = 1.000, and the standard deviation value ranges from 0.010 to 0.129 mg/L for wort and from 0.002 to 0.332 mg/L for beer. The mean concentrations of phenolic acids were 22.1 and 33.8 mg/L, respectively, in worts and beers produced in Italy. These amounts represent 5 and 10% of the non-tannic, non-flavonoid phenols in wort and beer, respectively.  相似文献   
60.
Furosine: a suitable marker for assessing the freshness of royal jelly   总被引:7,自引:0,他引:7  
Fifteen commercial samples of royal jelly, consisting of 10 imported samples, and 5 samples of known origin obtained freshly harvested from beekeepers, were analyzed for protein, lysine, and furosine content. In addition, a commercial sample of royal jelly, at the beginning of its commercial shelf life, was stored for 10 months both at 4 degrees C and at room temperature in order to assess the development of the Maillard reaction (furosine) and relative nutritional damage (blocked lysine). The commercial royal jelly products contained different amounts of furosine, ranging from 37.1 to 113.3 mg/100 g protein, evidence of different storage times and conditions. The average furosine content of the royal jelly samples of known origin and harvesting was significantly lower than that of the imported samples (41.7 versus 73.6 mg/100 g protein, respectively). With regard to shelf life, furosine content increased significantly from 72.0 mg/100 g protein to 500.8 mg/100 g protein after 10 months of storage at room temperature, while it increased to a much lower level (100.5 mg/100 g protein) when the royal jelly was stored at 4 degrees C. However, nutritional damage, expressed as blocked lysine (calculated indirectly from the furosine content), was minor or negligible, 11.9 and 2.3% of total lysine, in samples stored at room temperature and at 4 degrees C, respectively. Lysine was determined by an innovative procedure based on high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The results showed that furosine is a suitable index for assessing the quality and freshness of royal jelly.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号