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   2662篇
  免费   158篇
  国内免费   188篇
林业   105篇
农学   135篇
基础科学   314篇
  246篇
综合类   792篇
农作物   59篇
水产渔业   84篇
畜牧兽医   1129篇
园艺   28篇
植物保护   116篇
  2024年   13篇
  2023年   55篇
  2022年   53篇
  2021年   103篇
  2020年   70篇
  2019年   118篇
  2018年   48篇
  2017年   75篇
  2016年   118篇
  2015年   88篇
  2014年   103篇
  2013年   143篇
  2012年   233篇
  2011年   185篇
  2010年   139篇
  2009年   171篇
  2008年   151篇
  2007年   154篇
  2006年   131篇
  2005年   117篇
  2004年   104篇
  2003年   90篇
  2002年   86篇
  2001年   75篇
  2000年   57篇
  1999年   44篇
  1998年   38篇
  1997年   36篇
  1996年   33篇
  1995年   39篇
  1994年   24篇
  1993年   14篇
  1992年   16篇
  1991年   11篇
  1990年   20篇
  1989年   20篇
  1988年   14篇
  1987年   7篇
  1986年   4篇
  1985年   3篇
  1982年   1篇
  1980年   1篇
  1979年   1篇
  1956年   2篇
排序方式: 共有3008条查询结果,搜索用时 187 毫秒
41.
宋洁 《中国乳业》2021,(12):86-89
中国乳制品消费水平位于全球前三,奶牛养殖业在国内具有很大的发展潜力。随着奶牛养殖业的发展和扩大,繁殖疾病成为影响奶牛场经济效益的因素之一。繁殖疾病的发生和很多因素有关,包括营养、卫生等方面,体内激素不平衡也会诱发繁殖疾病的发生。本文对引起奶牛繁殖疾病的主要发病原因、临床症状、病理变化、临床诊断及治疗方法进行归纳总结,以期为繁殖疾病的诊断治疗提供理论基础。  相似文献   
42.
羊传染性胸膜肺炎是一种高度接触性传染性疾病,致病原是肺炎支原体。妊娠阶段的母羊受到病原侵染后表现为流产产下死胎,并表现出明显的繁殖障碍。近年,此病发生率逐年升高,造成的死亡现象不断增强,严重威胁养殖产业健康发展。作为养殖管理人员,应从该种疾病的流行病学、临床表现、病理变化和诊断方法等多角度入手,构建针对性的防治措施,严格落实预防为主的原则,为提高养殖效益奠定坚实的技术支撑。该文主要探讨羊传染性胸膜肺炎的防治过程。  相似文献   
43.
藏羊是青海地区农牧民群众养殖的特有羊品种,具有耐严寒、适应能力较强的特征。但在广大农牧地区,很多农民群众一直沿用散养养殖模式。整个羊群随着牧草的生长而迁徙,在放牧养殖过程中很容易受到多种寄生虫病的威胁,其中羊肝片吸虫病是威胁比较严重的一类人畜共患病。该文主要分析藏羊肝片吸虫病的流行病学、临床症状、病理变化、诊断方法和治疗措施。  相似文献   
44.
羊传染性脓痂皮炎又被称为羊传染性脓疱病、羊口疮病,是由羊传染性脓疱病毒感染引发的一种急性接触性传染性疾病。羊养殖主产区均有发生,是一种常见疾病。羊传染性脓痂皮炎虽然造成的死亡率较低,但是会严重影响羊群正常采食,造成营养物质供给不足,身体逐渐消瘦,抵抗能力变差,易继发感染多种传染性疾病,表现出复杂的临床症状,威胁羊群健康。  相似文献   
45.
猪副嗜血杆菌病作为对猪群生长发育带来严重危害性的一种细菌性传染疾病,不仅导致猪群质量下降,降低生猪养殖产业的经济效益。猪副嗜血杆菌病不会造成猪群较高的死亡率,但是对猪群在生长发育中的抵抗能力下降,极易感染多种传染性疾病,导致症状复杂,不利于疾病的诊断。该文主要对猪副嗜血杆菌病的诊断展开分析,论述流行特点、病例变化、临床症状等,并总结猪副嗜血杆菌病的防治方法。  相似文献   
46.
呼吸道疾病是目前威胁鸡养殖产业健康发展的一类重大动物疫病,呼吸道疾病的病原种类多种多样,且造成的临床症状大致相同,诊断难度较大,如果没有进行妥善有效的鉴别、诊断,易造成整体的治疗方案缺乏针对性,难以在短时间内控制病情,错过最佳的防控时期。鸡呼吸道疾病常常混合感染并发感染,2种以上的病原相互叠加表现的临床症状复杂,诊断难度更大。该文主要论述鸡呼吸道疾病的鉴别诊断和防治措施。  相似文献   
47.
Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives.  相似文献   
48.
We recently showed that two immunochromatography point-of-care FIV antibody test kits (Witness FeLV/FIV and Anigen Rapid FIV/FeLV) were able to correctly assign FIV infection status, irrespective of FIV vaccination history, using whole blood as the diagnostic specimen. A third FIV antibody test kit, SNAP FIV/FeLV Combo (an enzyme-linked immunosorbent assay [ELISA]), was unable to differentiate antibodies produced in response to FIV vaccination from those incited by FIV infection. The aim of this study was to determine if saliva is a suitable diagnostic specimen using the same well characterized feline cohort. FIV infection status of these cats had been determined previously using a combination of serology, polymerase chain reaction (PCR) testing and virus isolation. This final assignment was then compared to results obtained using saliva as the diagnostic specimen utilizing the same three point-of-care FIV antibody test kits and commercially available PCR assay (FIV RealPCR). In a population of cats where one third (117/356; 33%) were FIV-vaccinated, both immunochromatography test kits accurately diagnosed FIV infection using saliva via a centrifugation method, irrespective of FIV vaccination history. For FIV diagnosis using saliva, the specificity of Anigen Rapid FIV/FeLV and Witness FeLV/FIV was 100%, while the sensitivity of these kits was 96% and 92% respectively. SNAP FIV/FeLV Combo had a specificity of 98% and sensitivity of 44%, while FIV RealPCR testing had a specificity of 100% and sensitivity of 72% using saliva. A revised direct method of saliva testing was trialed on a subset of FIV-infected cats (n = 14), resulting in 14, 7 and 0 FIV positive results using Anigen Rapid FIV/FeLV, Witness FeLV/FIV and SNAP FIV/FeLV Combo, respectively. These results demonstrate that saliva can be used to diagnose FIV infection, irrespective of FIV vaccination history, using either a centrifugation method (Anigen Rapid FIV/FeLV and Witness FeLV/FIV) or a direct method (Anigen Rapid FIV/FeLV). Collection of a saliva specimen therefore provides an acceptable alternative to venipuncture (i) in fractious cats where saliva may be easier to obtain than whole blood, (ii) in settings when a veterinarian or trained technician is unavailable to collect blood and (iii) in shelters where FIV testing is undertaken prior to adoption but additional blood testing is not required.  相似文献   
49.
Although several reviews on canine leishmaniasis have been published, none thoroughly described clinicopathologic abnormalities and their clinical usefulness. The aim of this review was to provide information concerning current diagnostic tests relevant for clinical pathologists and from a practical perspective. Specifically, in canine leishmaniasis, nonregenerative normocytic normochromic anemia, thrombocytopenia, or leukogram changes may be present. Clinical chemistry and urinalysis may indicate renal dysfunction (azotemia, decreased urine specific gravity, proteinuria) and an inflammatory/immune response (increased acute phase proteins [APP] or α2‐ and/or γ‐globulins). Although a potential gammopathy is usually polyclonal, it may also appear oligo‐ or monoclonal, especially in dogs coinfected by other vector‐borne pathogens. When lesions are accessible to fine‐needle aspiration (lymphoadenomegaly, nodular lesions, joint swelling), cytology is strongly advised, as the presence of Leishmania amastigotes in a pattern of pyogranulomatous inflammation or lymphoplasmacytic hyperplasia is diagnostic. If the cytologic pattern is inconclusive, the parasite should be identified by histology/immunohistochemistry or PCR on surgical biopsies. Alternatively, cytology and PCR may be performed on bone marrow samples where amastigotes, along with erythroid hypoplasia, myeloid hyperplasia, plasmacytosis, or secondary dysmyelopoiesis can be observed. Dogs with overt leishmaniasis generally have high antibody titers, while low titers predominate in immunologically resistant infected dogs or in exposed dogs with no parasite confirmation. Quantitative serology is recommended in clinically suspect dogs as high‐titer antibodies titers may confirm the clinical diagnosis. In confirmed and treated dogs, renal function and inflammatory/immune response variables should be periodically monitored.  相似文献   
50.
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