全文获取类型
收费全文 | 3833篇 |
免费 | 148篇 |
国内免费 | 482篇 |
专业分类
林业 | 11篇 |
农学 | 102篇 |
基础科学 | 30篇 |
151篇 | |
综合类 | 1516篇 |
农作物 | 12篇 |
水产渔业 | 27篇 |
畜牧兽医 | 2597篇 |
园艺 | 7篇 |
植物保护 | 10篇 |
出版年
2024年 | 9篇 |
2023年 | 41篇 |
2022年 | 133篇 |
2021年 | 159篇 |
2020年 | 139篇 |
2019年 | 181篇 |
2018年 | 83篇 |
2017年 | 126篇 |
2016年 | 133篇 |
2015年 | 133篇 |
2014年 | 163篇 |
2013年 | 183篇 |
2012年 | 312篇 |
2011年 | 307篇 |
2010年 | 234篇 |
2009年 | 237篇 |
2008年 | 185篇 |
2007年 | 263篇 |
2006年 | 224篇 |
2005年 | 204篇 |
2004年 | 144篇 |
2003年 | 124篇 |
2002年 | 102篇 |
2001年 | 105篇 |
2000年 | 69篇 |
1999年 | 82篇 |
1998年 | 60篇 |
1997年 | 55篇 |
1996年 | 44篇 |
1995年 | 39篇 |
1994年 | 35篇 |
1993年 | 30篇 |
1992年 | 33篇 |
1991年 | 25篇 |
1990年 | 25篇 |
1989年 | 16篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有4463条查询结果,搜索用时 31 毫秒
11.
12.
复合酶高活性酵母对岭南黄肉鸡生产性能的影响 总被引:5,自引:1,他引:4
300只岭南黄肉鸡随机分为2组(每组设3个重复,每个重复50只),对照组饲喂基础日粮,试验组在基础日粮中用3%活性酵母替代3%豆粕。饲养试验结果表明:0~49日龄,平均末重、平均日增重、成活率试验组分别比对照组提高8.74%(P<0.05)、8.91%(P<0.05)和5.00%(P<0.05),试验组料蛋比比对照组下降11.25%(P<0.05)。代谢试验表明:能量表观利用率和粗蛋白质表观利用率试验组比对照组分别提高4.05%(P<0.05)和6.84%(P<0.05)。 相似文献
13.
Swayne DE Stockham SL Johnson GS 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1986,15(2):17-24
Generally accepted criteria were used to identify typical nucleated thrombocytes and typical small lymphocytes in chicken-blood smears subjected to modified-Wright staining. Other cells, here referred to as "intermediate cells," were difficult to classify because in some aspects they resembled thrombocytes while they also had features typical of small lymphocytes. The "intermediate cells" had small, round or oval nuclei with coarsely condensed chromatin, characteristic of both thrombocytes and small lymphocytes. In addition, "intermediate cells" had moderately abundant cytoplasmic volumes, typical of thrombocytes but blue cytoplasm lacking both granules and vacuoles, which is characteristic of small lymphocytes. It made little difference to the thrombocyte count whether these cells were classified as thrombocytes or small lymphocytes; however, this decision made a substantial difference to the lymphocyte count in some chicken-blood smears. Most "intermediate cells" (351 of 410 cells examined) were nonfluorescent after treatment with formaldehyde gas. Furthermore, most "intermediate cells" failed to acquire characteristic pigments when subjected to either Grimelius staining (179 of 204 cells examined) or periodic acid-Schiff staining (173 of 206 cells examined). Typical small lymphocytes reacted in the same way, failing to fluoresce after gaseous formaldehyde treatment (65 of 65 cells examined) and failing to react during Grimelius staining (41 of 44 cells examined) or periodic acid-Schiff staining (21 of 21 cells examined). In contrast, almost all typical thrombocytes became fluorescent in response to gaseous formaldehyde (709 of 718 cells examined) and gave positive reactions when subjected to Grimelius staining (381 of 382 cells examined) or periodic acid-Schiff staining (322 of 326 cells examined). These findings suggested that "intermediate cells" should be classified as lymphocytes in differential cell counts. 相似文献
14.
C. Darcel 《Veterinary research communications》1996,20(1):83-108
Diseases caused by lymphoid leukosis virus (LLV), a retrovirus, take a long time after infection to develop and have a wide variety of pathological manifestations. This long latent period is characteristic of persistent virus infections. Disease produced by LLV infection and its underlying mechanisms is compared with persistent infections caused by other retroviruses in birds and mammals of veterinary importance. The diseases considered for comparison are those caused by reticuloendotheliosis, feline leukaemia, bovine leukosis and equine infectious anaemia viruses. There are significant changes in the immunological status in all diseases caused by these viruses. LLV infections follow this trend with, in manifestations of neoplastic disease, a perturbation of the normal switch that occurs from IgM to IgG synthesis. There are also indications of other immunological disturbances.Factors other than immunological disturbances may contribute to the length of time after infection required for the many forms of LLV infection to appear. Such additional factors may include the operation of biological clocks, such as the arrival of sexual maturity, and also the very nature of retroviruses. These factors, like the immunological changes, play major roles in the maintenance and progression of persistent retrovirus infections.Abbreviations ACTH
adrenocorticotropic hormone
- AEV
avian erythroblastosis virus
- AMV
avian myeloblastosis virus
- BLV
bovine leukaemia virus
- CAV
chicken anaemia virus
- EBL
enzootic bovine leukaemia
- EIAV
equine infectious anaemia virus
- env
envelope gene
- FeLV
feline leukaemia virus
- FeSV
feline sarcoma virus
- FOCMA
feline oncovirus membrane-associated antigen; gag, group antigen gene
- HTLV
human T-cell leukaemia virus
- LLV
lymphoid leukosis virus
- L/S
leukosis/sarcoma
- LTR
long terminal repeat
- MAV
myeloblastosis-associated virus
- MDV
Marek disease virus
- MuLV
mouse leukaemia virus
- ORF
open reading frame; pol, polymerase gene
- REV
reticuloendotheliosis virus
- RIF
resistance-inducing factor
- RSV
Rous sarcoma virus 相似文献
15.
以江苏省家禽科学研究所家禽育种中心崇仁麻鸡♂×(崇仁麻鸡♂×隐性白羽鸡新品系♀)♀(配套1)和固始鸡♂×(崇仁麻鸡♂×隐性白羽鸡新品系♀)♀(配套2)为素材,进行肉用性能试验,结果表明①两配套组合体重差异极显著(P<0.01),配套2比配套1重109.6克且饲料报酬高0.171;②两配套组合龙骨长、冠长、冠高、胸宽差异不显著(P>0.05),体斜长、胫长、胫围、胸角差异极显著(P<0.01),配套2均高于配套1.③两配套组合屠体率、半净膛率、全净膛率、胸肌率、腹脂率差异不显著(P>0.05),配套1腿肌率显著高于配套2(P<0.05).④两配套组合胸肌失水率、PH值、肉色、剪切力差异不显著(P>0.05).总体而言,配套2的肉用性能优于配套1,隐性白羽鸡新品系在优质鸡配套系中应用是可行的. 相似文献
16.
鸡球虫对机体的致病作用研究进展 总被引:3,自引:0,他引:3
球虫在鸡体内进行生命活动的同时对鸡体产生不同程度的损害,球虫感染后的致病性和病理学反应是球虫与宿主机体相互作用的结果。本文就鸡球虫致病作用及其对宿主细胞代谢的影响、及影响球虫致病性的因素的研究进展予以综述,对鸡球虫病的防治具有一定的指导意义。 相似文献
17.
18.
重组鸡IL-2增强鸡四联灭活苗免疫效果的研究 总被引:10,自引:2,他引:10
使用在原核表达系统中表达的重组鸡白细胞介素 2 (IL 2 )蛋白 ,经过初步的分离纯化 ,与鸡新城疫 禽流感 法氏囊 传染性支气管炎四联油乳剂灭活苗同时使用 ,检测其对疫苗的免疫增强效果。试验共分 5组 ,每组 1 0只鸡。其中对照组只注射四联油乳剂灭活苗 ;4个试验组 ,在注射疫苗的同时分别注射重组鸡IL 2蛋白 0 0 5mg、 0 0 1mg、 0 1 5mg、 0 2 0mg。试验组与对照组同时各注射新城疫等多联油苗 0 5mL。采用HA、HI试验测定鸡新城疫、禽流感抗体滴度。结果表明 :重组鸡IL 2对该四联油乳剂灭活苗有较强的免疫增强作用。以第 3、 4组的增强效果较为明显 ,其中对鸡新城疫病毒和禽流感抗原的抗体效价 ,与对照组相比分别提高 2 42 8和 2 2 3 0个滴度。重组鸡IL 2在使用的过程中 ,没有发现任何毒副作用 ,证明是一种安全高效的免疫增强剂。 相似文献
19.
隐性白羽肉鸡及其配套地方鸡部分血液生化指标的测定 总被引:1,自引:1,他引:1
本试验测定了我校最新育成的隐性白羽肉鸡快慢羽系父系、母系及其配套地方鸡广西黄鸡和文昌鸡主要的血液生化指标。结果表明,四个品系血清总蛋白、白蛋白、葡萄糖、胆固醇、Ca含量接近,血清P、K、Na含量A系最高,显著(P<0.05)或极显著(P<0.01)高于其它三系,各品系内公母之间母鸡的血Ca均极显著(P<0.01)高于公鸡。血清淀粉酶(AMY)活力和肌酸磷酸激酶(CK)活力B系极显著(P<0.01)高于其它三系,血清碱性磷酸酶(AKP)活力品系间差异不显著(P>0.05)。 相似文献
20.
江苏某鸡场饲养的蛋鸡,呼吸道病很严重,用药物和现有的疫苗控制效果都不够理想。为此,将该鸡场发生呼吸道病病鸡的病料进行收集,制成油佐剂灭活苗对鸡进行免疫接种,结果获得满意的效果。 相似文献