全文获取类型
收费全文 | 2712篇 |
免费 | 246篇 |
国内免费 | 286篇 |
专业分类
林业 | 80篇 |
农学 | 193篇 |
基础科学 | 28篇 |
290篇 | |
综合类 | 1014篇 |
农作物 | 270篇 |
水产渔业 | 335篇 |
畜牧兽医 | 480篇 |
园艺 | 79篇 |
植物保护 | 475篇 |
出版年
2024年 | 39篇 |
2023年 | 90篇 |
2022年 | 154篇 |
2021年 | 166篇 |
2020年 | 167篇 |
2019年 | 153篇 |
2018年 | 123篇 |
2017年 | 146篇 |
2016年 | 174篇 |
2015年 | 146篇 |
2014年 | 155篇 |
2013年 | 152篇 |
2012年 | 157篇 |
2011年 | 166篇 |
2010年 | 118篇 |
2009年 | 103篇 |
2008年 | 114篇 |
2007年 | 107篇 |
2006年 | 107篇 |
2005年 | 79篇 |
2004年 | 71篇 |
2003年 | 67篇 |
2002年 | 66篇 |
2001年 | 59篇 |
2000年 | 49篇 |
1999年 | 37篇 |
1998年 | 38篇 |
1997年 | 25篇 |
1996年 | 24篇 |
1995年 | 37篇 |
1994年 | 19篇 |
1993年 | 17篇 |
1992年 | 25篇 |
1991年 | 15篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 1篇 |
1956年 | 4篇 |
1955年 | 3篇 |
排序方式: 共有3244条查询结果,搜索用时 15 毫秒
31.
32.
I. C. Johns E. J. T. Finding T. Ciasca K. Erles K. Smith R. Weller 《Equine Veterinary Education》2014,26(6):294-298
This case report describes an unusual diagnosis of central nervous system botryomycosis in a horse. A 16‐year‐old Welsh Section D gelding was evaluated for acute onset of hypermetric ataxia, leaning to the left and head tilt to the right. Based on the neurological signs, a cerebellar lesion with accompanying vestibular disease was suspected and supportive therapy consisting of antimicrobial and glucocorticosteroid drugs and hypertonic saline was instituted. This resulted in marked clinical improvement over a 48 h period. Computed tomography performed in the standing, sedated horse following initial stabilisation identified extensive sclerosis and lysis of the right temporal and occipital bones, consistent with an infectious or neoplastic process. Based on the grave prognosis for survival despite the clinical improvement, euthanasia was undertaken. Post mortem magnetic resonance imaging identified a mass lesion impinging on the right cerebellar hemisphere, sclerosis of the temporal and occipital bones lateral and ventral to the mass, as well as destruction of the temporal bone between the inner ear and the cerebellum. These changes corresponded to the presence of a mass within the right dorsal temporal bone, extending into the right lateral temporal bone. The mass extended to compress and adhere to the right lateral hemisphere of the cerebellum. A histopathological diagnosis of botryomycosis was made, affecting the temporal and occipital bones and compressing the cerebellum. 相似文献
33.
34.
为探究祁连山中段不同退化高寒草地土壤细菌群落分布特征,采用Illumina HiSeq PE250高通量测序平台对轻度、中度和重度退化草地土壤细菌群落变化特征进行研究,并对土壤细菌群落与土壤酶活性、土壤理化因子间关系进行分析。结果表明:随着退化程度加剧,植被盖度、高度、地上生物量和多样性指数均明显降低(P<0.05);土壤理化性质和酶活性变化各异且差异显著(P<0.05)。高通量测序共得到257971条有效序列,219017条优质序列和2004个OTUs。细菌群落丰富度指数依次为轻度>中度>重度,多样性指数为轻度>重度>中度,Beta多样性分析表明各样地间差异为轻度>重度>中度。其中,放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、酸杆菌门(Acidobacteria)和变形菌门(Proteobacteria)为3种退化草地土壤的优势菌门,在轻度、中度和重度退化草地土壤中分别占77.25%、84.27%和78.66%;乳球菌属为3种退化草地土壤的优势菌属,在轻度、中度和重度退化草地土壤中分别占14.29%、38.84%和7.39%。冗余分析表明:土壤酶活性和土壤理化性质均对细菌群落的组成具有影响,其中土壤pH是影响土壤细菌群落分布的主要驱动因子。祁连山中段不同退化高寒草地土壤细菌群落的变化主要受土壤理化性质和酶活性的影响。 相似文献
35.
E. Smiet G. C. M. Grinwis J. G. B. van den Top M. M. Sloet van Oldruitenborgh‐Oosterbaan 《Equine Veterinary Education》2012,24(7):357-366
Mammary gland problems occur incidentally in horses and one of the rarer conditions is botryomycosis (bacterial pseudomycosis, bacterial granuloma, staphylococcal pseudomycetoma). This article includes a short review of equine mammary gland problems inappropriate lactation, mastitis and neoplasia and botryomycosis, and additionally 2 clinical cases of botryomycosis of the udder resulting from Staphyloccocus aureus infection will be discussed. Both cases involved nonpregnant, nonlactating mares referred for chronic mammary inflammation with draining abcessation. In both mares, botryomycosis caused by S. aureus was confirmed by histopathology and a bacterial culture. Both mares recovered fully after surgical hemimastectomy under general anaesthesia. 相似文献
36.
按照《中国兽药典》二○○五年版一部[1]中注射用硫酸链霉素细菌内毒素检查法对样品复核检验,试验表明该方法是可行的;并与《美国药典》进行了比较,结果说明《中国兽药典》注射用硫酸链霉素细菌内毒素检查法对细菌内毒素的限值表达比《美国药典》29版[2]更合理、更科学。 相似文献
37.
将含有裂解酶基因重组温控裂解质粒pBBR1MCS::PR-PL-E电转化至粗糙型布鲁菌M111中,构建重组布鲁菌M111(pBBRlMCS::PR-PL-E)。重组菌株在28℃培养,42℃诱导表达裂解酶E,从而制备布鲁菌菌壳。绘制布鲁菌生长曲线及裂解曲线,计算裂解率并用透射电镜观察布鲁菌菌壳的形态。结果显示,成功制备了布鲁菌菌壳,温控裂解质粒pBBRIMCS::PR-PL-E对布鲁菌的裂解率为100%。透射电镜观察可见细菌内容物部分流出,细菌表面出现不同程度的皱缩,细胞形态发生变化。结果表明,本试验成功制备了粗糙型布鲁菌菌壳,初步研究了其基本特性,为下-步开展布鲁菌菌壳疫苗的研究奠定了基础。 相似文献
38.
Polysaccharide is the major component of bacterial cell that plays a significant role in the interaction between bacteria and their hosts. It aids the identification of bacteria, imparting virulence to the bacteria and adjusting host's immune response as well. Advance genomics research has deciphered several different bacterial polysaccharides sharing a common biosynthesis mechanism. The study of polysaccharides is mainly based on sequence analysis and prediction of genome in combination with metabolite analyses that still requires a detailed study. Researchers are now further focusing on their biosynthetic pathways to unveil the mechanisms underlying the diversity of these bacterial polysaccharides along with the host-pathogen interaction. It will open new doors for vaccine development and other therapeutic methods against pathogenic bacteria, and also provide technical support to control disease and cure at molecular level. This review states the mechanisms and relevant problems of biosynthesis and in vitro biosynthesis of peptidoglycan,O-antigen and capsular polysaccharides,and summarizes the application of bacteria polysaccharides in the aspects of searching for candidate antigens and controlling the targets of pathogenic bacteria and exploring genetic evolution of bacteria and biological synthesis. 相似文献
39.
为了解云南省断奶仔猪腹泻的致病性原因,通过对30个发生断奶仔猪腹泻猪场的210份粪便、60份饮用水,总计270份样品,进行病毒及致病性细菌分析。研究结果表明,致病性大肠杆菌严重污染饮用水,致病性大肠杆菌在饮用水中检出40株,阳性率为66.7%,粪便中检出100株,阳性率47.6%;致病性沙门氏菌在饮用水中检出10株,阳性率为16.7%,粪便中检出24株,阳性率为11.4%,均对亚胺培南敏感。在粪便中猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)、猪圆环病毒2型(porcine circovirous type 2,PCV2)、猪伪狂犬病病毒(pseudorabies virus,PRV)、猪瘟病毒(classical swine fever virus,CSFV)、猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)及猪轮状病毒(porcine rotavirus,PoRV)的PCR扩增阳性率为5.2%~13.0%,在饮用水中未检出。通过对云南省断奶仔猪腹泻进行病因分析,了解断奶仔猪腹泻的具体原因,本试验结果为从病因入手防制该病提供更合理、更切合实际情况的理论依据与试验参考。 相似文献
40.
Takumi Shinkai Takaaki Ueki Satoshi Koike Yasuo Kobayashi 《Animal Science Journal》2014,85(3):254-261
To determine the relationship between Fibrobacter succinogenes and other rumen bacteria, the bacterial community structure on fiber was analyzed by using two different materials. These were ruminally incubated orchard grass hay stems without and with preincubation with F. succinogenes (natural and artificial consortia, respectively). The natural consortium mainly consisted of Firmicutes (56.6%) and Bacteroidetes (33.1%), while the artificial consortium showed a significantly higher proportion of Firmicutes (85.5%) and a lower proportion of Bacteroidetes (4.6%). At species or genus level, Butyrivibrio fibrisolvens, the U2 group, Ruminococcus albus and Lachnospiraceae incertae sedis made up a higher proportion in the artificial consortium. The most dominant bacterial group was the Butyrivibrio‐Pseudobutyrivibrio‐Lachnospiraceae incertae sedis group, which accounted for 19.7% in the natural and 29.5% in the artificial consortium. Within the genus Butyrivibrio, the phylogenetic groups SA and VA2 and phylogeny‐undefined Butyribivrio, but not VA1, were detected at high frequency in the artificial consortium. These results suggest that ecological and possibly functional relationships exist in the rumen among F. succinogenes, a subset of B. fibrisolvens, the U2 group, R. albus and Lachnospiraceae incertae sedis. 相似文献