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   220篇
  免费   11篇
  国内免费   16篇
林业   24篇
农学   8篇
基础科学   2篇
  21篇
综合类   17篇
农作物   13篇
水产渔业   13篇
畜牧兽医   127篇
园艺   4篇
植物保护   18篇
  2024年   1篇
  2023年   1篇
  2022年   1篇
  2021年   7篇
  2020年   5篇
  2019年   4篇
  2018年   2篇
  2017年   8篇
  2016年   6篇
  2015年   5篇
  2014年   2篇
  2013年   36篇
  2012年   6篇
  2011年   14篇
  2010年   10篇
  2009年   12篇
  2008年   7篇
  2007年   8篇
  2006年   6篇
  2005年   5篇
  2004年   6篇
  2003年   7篇
  2002年   8篇
  2001年   6篇
  2000年   6篇
  1999年   5篇
  1998年   3篇
  1997年   5篇
  1996年   1篇
  1992年   4篇
  1991年   2篇
  1990年   8篇
  1989年   3篇
  1988年   1篇
  1987年   8篇
  1985年   6篇
  1984年   4篇
  1983年   1篇
  1981年   1篇
  1978年   1篇
  1975年   2篇
  1973年   1篇
  1972年   4篇
  1970年   3篇
  1953年   1篇
  1945年   2篇
  1942年   1篇
  1935年   1篇
排序方式: 共有247条查询结果,搜索用时 15 毫秒
51.
引进5个番茄品种,进行了秋延后栽培试验,结果显示秋延后日光温室番茄品质好,深受广大消费者的欢迎。  相似文献   
52.
Earthworms (Oligochaeta,Lumbricidae) and mycobacteria   总被引:4,自引:0,他引:4  
The objective of the study was to define the role of earthworms in the survival of mycobacteria in animal populations. In 13 sampling sites mycobacteria were detected in 53 (5.5%) samples of faeces and parenchymatous tissues from animals, in 25 (7.3%) environmental and in nine (8.2%) earthworm samples. In cattle and goat farms affected by Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) of IS900 restriction fragment length polymorphism (RFLP) type B-C1 was isolated from 37 (4.6%) faecal samples, three (1.4%) environmental and one (3.1%) earthworm sample. Investigations of aviaries affected by avian tuberculosis detected M. avium of genotype IS901+ and IS1245+ in six (7.9%) bird's faecal and in four (4.4%) environmental samples. M. avium (genotype IS901- and IS1245+) was detected in four (4.4%) and M. abscessus in one (1.1%) environmental sample. M. avium of genotype IS901- and IS1245+ and M. gastri were isolated from three (6.4%) earthworm samples. In pig farm with mycobacteriosis M. avium of genotype IS901- and IS1245+ was detected in five (20.0%) faecal samples from pigs and in four (12.9%) environmental samples. M. scrofulaceum was isolated in one (4.6%) sample of Lumbricus rubellus. In laboratory experiments identical RFLP types of M. paratuberculosis were isolated from bodies and faeces of earthworms 1-2 days after the last contact with the faeces contaminated with the same RFLP type of M. paratuberculosis. The results suggest that earthworms may become vectors of mycobacteria.  相似文献   
53.
Pelvic limb specimens from 14 euthanized free-ranging lions (Panthera leo), ranging in age from 16 to 170 mo, underwent radiographic evaluation in the manner described for thoracic limbs in part I of this study. On the basis of these specimens, the femur of the lion is similar to that of domestic cats, but the cranial and caudal middiaphyseal cortices are markedly thickened. The patella has a long narrow apex and flat broad base. There is a prominent lateral Os sesamoideum m. gastrocnemii. A small medial sesamoid is occasionally present, and meniscal ossicles are usually present. The head and distal extremity of the fibula are very prominent. The tarsal joint is similar to that of domestic cats. Metatarsals II-V are up to 25 mm longer than the corresponding metacarpals. All physes close by 54 mo of age.  相似文献   
54.
55.
56.
57.
Temperature-humidity index (THI) values applicable to South Africa and Namibia have been established during this investigation for each month of the year by means of computerized modelling and mapping techniques. The data indicate that each year heat stress risk areas (HSRA's) expand from August to January and retract from February to July. The THI values classified according to the Livestock Weather Safety Index (LWSI) for lactating dairy cattle (LDC), suggest that, especially during November to March there is the risk of moderate to advanced heat stress in most South African dairy cows. This has important implications for their general health, udder health, production and reproduction. Careful planning of facilities and highly adaptable herd management are required to protect dairy cattle from heat stress.  相似文献   
58.
Thoracic limb specimens from 12 euthanized free-ranging lions (Panthera leo, 16-170 mo old) underwent radiographic evaluation. The radiographic anatomy was described but excluded any areas of the bones with possible bone pathology. Comparisons between adult and juvenile lions were made and physes described. Differences or similarities (or both) to cheetahs (Acinonyx jubatus) and domestic cats and dogs were also noted. No dissections were made to corroborate the anatomic observations, but comparisons were made to macerated museum specimens. On the basis of evaluation, the scapula has a prominent acromion, hamate, and suprahamate processes, as well as prominent nutrient foramina. The humerus is similar to that of domestic cats. The humeral and ulnar nutrient foramina originate more medially than that in domestic cats. A supracondylar foramen may sometimes be observed radiologically, although one was present on all the macerated specimens in this study. Its radiologic visibility depends on the angle of incidence of the primary beam. The lateral "anconeal tubercle" of the olecranon (situated between the processus anconeus and tuber olecrani) is usually more prominent than the medial one and tends to be hook shaped, pointing cranially. There are no sesamoids in the region of the elbow. The first digit is large with two palmar metacarpophalangeal sesamoids and a prominent sesamoid in the tendon of the M. abductoris digiti I longus, all indications of a high degree of functionality. All physes close before 66 mo of age.  相似文献   
59.
A workshop was held at Onderstepoort on 2-3 July 1999 to set priorities in veterinary helminthology for South Africa. Representatives from 19 organisations attended. The workshop achieved 2 of its 3 aims, namely to identify the priority areas within the field and to set specific objectives to be achieved in addressing these needs. Seven strategies were proposed, namely, motivation, education, therapeutic, worm resistance, animal tolerance, biological control and diagnostic strategies. A follow-up session took place on 8 September 1999 and at this workshop and in subsequent meetings, preliminary action plans were developed for these strategies. It was felt that the proposed activities delineated by this process should form the basis for a National Programme for Veterinary Helminthology and a national forum is to be convened to encourage all stakeholders to consider, discuss and adopt these activities. The forum is scheduled to take place in April 2000.  相似文献   
60.
Neopolystoma liewi sp. n. is described from the conjunctival cavity of the Malayan box turtle Cuora amboinensis (Daudin, 1802), in Peninsular Malaysia. This is the first record of Neopolystoma in Malaysia and the fourth polystomatid species described from C. amboinensis. Of the 27 Malayan box turtles examined, 8 were found to be infected. A maximum of 2 parasites per eye and 4 individuals per host was recorded. N. liewi sp. n. differs from all other members of the genus by possessing few and short genital spines and small marginal hooks. The oncomiracidium has 64 ciliated cells arranged symmetrically about the sagittal axis.  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