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   63篇
  免费   2篇
  国内免费   1篇
林业   1篇
农学   2篇
  4篇
综合类   14篇
农作物   3篇
畜牧兽医   32篇
园艺   2篇
植物保护   8篇
  2021年   1篇
  2019年   2篇
  2018年   1篇
  2016年   3篇
  2015年   1篇
  2014年   2篇
  2013年   5篇
  2012年   2篇
  2010年   3篇
  2008年   3篇
  2007年   3篇
  2006年   2篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2002年   3篇
  2000年   8篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1996年   4篇
  1993年   2篇
  1992年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1985年   3篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1956年   1篇
  1952年   1篇
排序方式: 共有66条查询结果,搜索用时 15 毫秒
41.
The effect of three commonly used anthelmintics, levamisole hydrochloride, ivermectin and closantel, on the development of the sheep blowfly, Lucilia cuprina, was determined. Sheep were treated with each anthelmintic using the manufacturers' recommended dose for helminth control. Both ivermectin and closantel significantly (p < 0.05) reduced the growth rate of larvae of L cuprina cultured in vitro on serum from these sheep. Levamisole hydrochloride had no effect. Ivermectin was effective for less than 6 days after treatment, whereas closantel significantly reduced larval growth 21 days after treatment. Dose-response experiments showed that lower concentrations of both ivermectin and closantel were not as effective in reducing larval growth.  相似文献   
42.
A Burdizzo castrator was evaluated for the neutering of dogs. Histological and morphological changes of spermatic cells and peripheral serum testosterone after challenge with a GnRH-analogue (gonadorelin) were assessed. There was a control group (G1), a surgically castrated group (G2) and a Burdizzo group (G3) divided in two, G3a receiving two crunches in each spermatic cord and G3b receiving one crunch in each spermatic cord. Sixteen days after application of the Burdizzo blood samples were taken from the dogs at 30 min interval during 2 h; after the second sample the dogs were treated with 1 mug/kg body weight of gonadorelin i.v. The same protocol of gonadorelin challenge was performed in G1 and G2 dogs. The G2 dogs were surgically castrated after the second blood sample, before the gonadorelin treatment, and the G1 dogs after the last blood sample. The excised gonads were examined histologically, and sperm smears were prepared from the caudae epididymidis. The testes and plexus pampiniformis of the G1 and G2 dogs had a normal histological appearance, and they had morphologically normal epididymal sperm cells. In all G3 dogs, there was an acute fibrosis with an inflammatory reaction in the plexus pampiniformis. The testes from the G3a dogs showed diffuse areas of infarction and degeneration of the parenchyma. Similar but less diffuse lesions were seen in group 3b dogs. The deferent ducts from all G3 dogs showed vasitis and/or sperm granulomas. Azoospermia or sperm malformations were observed in the epididymal smears from the G3 dogs. Testosterone concentration in the G1 dogs increased after gonadorelin application (p < 0.0001). The G2 dogs had basal testosterone levels after castration (p < 0.001) and did not respond to gonadorelin. Groups 3a and b showed a slight but non-significant increase in testosterone concentration after gonadorelin challenge, supposedly due to the reduction of testicular blood flow and loss of testicular interstitial tissue.  相似文献   
43.
44.
45.
Occurrence of Fusarium wilt of common heliotrope(Heliotropium europaeum L.) is reported. Pathogenicity of the causal agent was confirmed by reisolation from inoculated heliotrope plants. The specificity of the isolate was shown by cross-inoculation tests with five formae speciales and by inoculating the five respective hosts with a monoconidial isolate of the present fungus. Only the latter fungus was found to incite wilt in common heliotrope; the proposed name of this forma specialis isFusarium oxysporum f. sp.heliotropae nov. f.  相似文献   
46.
The commercial available diatomaceous earth Fossil Shield® and the neem product Neem Azal-T/S® are tested as single treatments and in combination as controls for the stored product pests Sitophilus oryzae (L.) and Tribolium castaneum (Herbst). The diatomaceous earth, applied in concentrations of 0.5 g, 1 g and 2 g kg-1 rice, reduced numbers of surviving beetles significantly (over a period of 3 weeks). A single treatment with the neem product, in concentrations of 0.01 g, 0.1 g, 0.2 g and 1 g azadirachtin kg-1 rice, increased the mortality rate for both species significantly. The combination of neem and diatomaceous earth (1 g diatomaceous earth with 0.2 g or 1 g azadirachtin kg-1 rice) was more effective than the single treatment in reducing numbers of surviving beetles.  相似文献   
47.
48.
Biodiversity assessment and conservation strategies   总被引:2,自引:0,他引:2  
The efficient representation of all species in conservation planning is problematic. Often, species distribution is assessed by dividing the land into a grid; complementary sets of grids, in which each taxon is represented at least once, are then sought. To determine if this approach provides useful surrogate information, species and higher taxon data for South African plants and animals were analyzed. Complementary species sets did not coincide and overlapped little with higher taxon sets. Survey extent and taxonomic knowledge did not affect this overlap. Thus, the assumptions of surrogacy, on which so much conservation planning is based, are not supported.  相似文献   
49.

Extract

Ectoparasites known to cause skin lesions in alpacas (Vicugna pacos) include the mites Sarcoptes scabiei, Chorioptes bovis and Psoroptes spp., and the lice Microthoracius mazzai and Bovicola breviceps (Cicchino et al. 1998 Cicchino, AC, Munoz, Cobenas ME, Bulman, GM, Diaz, JC and Laos, A. 1998. Identification of Microthoracius mazzai (Phthiraptera: Anoplura) as an economically important parasite of alpacas. Journal of Medical Entomology, 35: 922930.  [Google Scholar]; Foster et al. 2007 Foster, A, Jackson, A and D'alterio, GL. 2007. Skin diseases of South American camelids. In Practice, 29: 216223. [Crossref], [Web of Science ®] [Google Scholar]). Occasionally, Demodex spp. infestations have been reported or mentioned as incidental fi ndings in llamas (Lama glama) (Atlee et al. 1997 Atlee, BA, Stannard, AA, Fowler, ME, Willemse, T, Ihrke, PJ and Olivry, T. 1997. The histology of the normal llama skin. Veterinary Dermatology, 8: 165176. [Crossref], [Web of Science ®] [Google Scholar]) and alpacas (Foster et al. 2007 Foster, A, Jackson, A and D'alterio, GL. 2007. Skin diseases of South American camelids. In Practice, 29: 216223. [Crossref], [Web of Science ®] [Google Scholar]). So far, only Sarcoptes scabiei (McKenna et al. 2005 McKenna, PB, Hill, FI and Gillett, R. 2005. Sarcoptes scabiei infection on an alpaca (Lama pacos. New Zealand Veterinary Journal, 53: 213213. [Taylor &; Francis Online], [Web of Science ®] [Google Scholar]), Chorioptes bovis (Arthur 1997 Arthur, DG. 1997. Diseases of lamoids in New Zealand. Surveillance, 24(1): 2930.  [Google Scholar], non-peer reviewed) and Bovicola breviceps (Palma et al. 2006 Palma, RL, McKenna, PB and Aitken, P. 2006. Confirmation of the occurrence of the chewing louse Bovicola (Lepikentron) breviceps (Insecta: Phthiraptera: Trichodectidae) on alpacas (Lamas pacos) in New Zealand. New Zealand Veterinary Journal, 54: 253254. [Taylor &; Francis Online], [Web of Science ®] [Google Scholar]) have been recorded on lamoids in New Zealand. Here, we report the first record of Demodex spp. infestation of an alpaca in New Zealand.  相似文献   
50.
在虚拟的网络世界中, 构建网络道德, 很大程度上要依赖于网络传播者的道德和素质。本课题试图通过探讨网络传播者的思想道德素质状况, 分析如何加强传播者的网络道德教育, 提升其道德自律能力, 从而促进网络道德体系和网络文明建设。  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