全文获取类型
收费全文 | 5026篇 |
免费 | 292篇 |
国内免费 | 499篇 |
专业分类
林业 | 252篇 |
农学 | 247篇 |
基础科学 | 77篇 |
388篇 | |
综合类 | 1786篇 |
农作物 | 165篇 |
水产渔业 | 348篇 |
畜牧兽医 | 2105篇 |
园艺 | 64篇 |
植物保护 | 385篇 |
出版年
2024年 | 30篇 |
2023年 | 92篇 |
2022年 | 161篇 |
2021年 | 232篇 |
2020年 | 227篇 |
2019年 | 188篇 |
2018年 | 128篇 |
2017年 | 184篇 |
2016年 | 217篇 |
2015年 | 190篇 |
2014年 | 275篇 |
2013年 | 286篇 |
2012年 | 393篇 |
2011年 | 390篇 |
2010年 | 322篇 |
2009年 | 343篇 |
2008年 | 270篇 |
2007年 | 328篇 |
2006年 | 272篇 |
2005年 | 200篇 |
2004年 | 156篇 |
2003年 | 140篇 |
2002年 | 99篇 |
2001年 | 102篇 |
2000年 | 73篇 |
1999年 | 82篇 |
1998年 | 41篇 |
1997年 | 55篇 |
1996年 | 36篇 |
1995年 | 38篇 |
1994年 | 48篇 |
1993年 | 34篇 |
1992年 | 33篇 |
1991年 | 24篇 |
1990年 | 25篇 |
1989年 | 28篇 |
1988年 | 12篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1956年 | 7篇 |
排序方式: 共有5817条查询结果,搜索用时 15 毫秒
111.
昌潍白猪内分泌腺的生长发育规律 总被引:1,自引:0,他引:1
系统研究了1~8月龄昌潍白猪(192头)内分泌腺的性状指标,并由此得出了其内分泌腺的生长发育规律及其与体重变化的回归方程.结果表明,肾上腺在1~3、5~6月龄生长速度最快(P<0.01);甲状腺在1~8月龄有2个生长高峰期,即4月龄和6月龄;胸腺的生长高峰期集中于3~4月龄(P<0.01),颈部胸腺在1~3月龄生长速度显著快于胸部胸腺,胸部胸腺左侧生长发育明显快于右侧;脑垂体在2~6月龄生长速度较快.肾上腺、甲状腺、胸腺、脑垂体随体重变化的回归方程分别是y=0.019 9x+0.801 6(r=0.975 9,P<0.01);y=0.163 4x+1.286 8(r=0.976 1,P<0.01);y=1.760 8x+26.995 0(r=0.946 2,P<0.01);y=0.002 4x+0.062 0(r=0.908 3,P<0.01). 相似文献
112.
113.
碱性诺氟沙星在健康猪体内的药动学 总被引:5,自引:0,他引:5
按 10 mg/kg单一剂量对健康猪分别肌注和静注碱性诺氟沙星注射液后 ,研究了其在猪体内的药代动力学。应用 HPL C法测定猪体内的血药浓度 ,所得数据应用 MCPKP药动学软件处理 ,结果为 :肌注碱性诺氟沙星 ,Cmax(2 .6 30 80± 0 .6 830 6 ) mg/L,T1 /2 (6 .0 75 17± 3.0 4 76 1) h,AUC(12 .4 99± 2 .4 2 3) mg/L· h,F4 8.4 % ;静注碱性诺氟沙星 ,Co(12 .736 4 8± 5 .1835 2 ) mg/L,T1 /2 (3.312 89± 0 .4 84 39) h,AUC(2 5 .74 7± 3.14 9) mg/L·h。 相似文献
114.
115.
规模化猪场粪污处理技术研究进展 总被引:13,自引:0,他引:13
我国规模化猪场的兴起与粪污处理的相对滞后,使养殖业对环境的污染日益严重,畜牧场的污染问题已越来越受到人们的关注和重视。通过营养调控的方式可以提高动物对养分利用率,从而减少动物代谢废物的排泄量,但动物的粪污排泄量仍大大超出环境的承受能力,因此必须加强猪场废弃物和污水的综合治理。本文就国内外粪污处理技术和(粪)污水处理的工艺等方面研究近况作一综述。 相似文献
116.
猪弓型虫病又称猪弓形体病、弓原虫病。是由垄地弓行虫寄生于各种动物的细胞内引起的一种人、畜共惠的原虫病,该病以患病动物的高热,呼吸及神经系统症状,动物死亡和妊娠动物的流产、死胎、胎儿畸形为特征。暴发弓形体病时,可使整个猪场发病,死亡率可高达60%以上。目前全国各地均有本病的存在,给人类健康和畜牧业发展带来了很大的危害和威胁。本试验对猪临床发病病例经过流行病学调查、临床症状及剖检变化观察、最后经过实验室检查确诊为猪弓形虫病。应用复方蒲公英注射液进行治疗,结果有效率为100%。治愈率为95%,与对照组差异显著(P〈005),可以在临床推广使用。 相似文献
117.
Antigenic Detection of Human Strain of Influenza Virus A (H3N2) in Swine Populations at Three Locations in Nigeria and Ghana during the Dry Early Months of 2014 下载免费PDF全文
Since the first detection of human H3N2 influenza virus in Taiwanese pigs in 1970, infection of pigs with wholly human viruses has been known to occur in other parts of the world. These viruses, referred to as human‐like H3N2 viruses, have been known to cause clinical and subclinical infections of swine populations. Due to the paucity and complete unavailability of information on transmission of influenza viruses from other species, especially humans, to swine in Nigeria and Ghana, respectively, this study was designed to investigate the presence and prevalence of a human strain of influenza A (H3N2) in swine populations at three locations in two cities within these two West African countries in January and February, 2014. Using stratified random technique, nasal swab specimens were collected from seventy‐five (75) pigs at two locations in Ibadan, Nigeria and from fifty (50) pigs in Kumasi, Ghana. These specimens were tested directly by a sensitive Quantitative Solid Phase Antigen‐detection Sandwich ELISA using anti‐A/Brisbane/10/2007 haemagglutinin monoclonal antibody. Influenza virus A/Brisbane/10/2007 (H3N2) was detected among pigs at the three study locations, with an aggregate prevalence of 4.0% for the two locations in Ibadan, Nigeria and also 4.0% for Kumasi, Ghana. Transmission of influenza viruses from other species to swine portends serious sinister prospects for genetic reassortment and evolvement of novel viruses. We therefore recommend that further studies should be carried out to investigate the presence of other circulating human and avian influenza viruses in swine populations in West Africa and also determine the extent of genetic reassortment of strains circulating among these pigs. This would provide an early warning system for detection of novel influenza viruses, which could have pandemic potentials. 相似文献
118.
高效液相色谱法测定猪血浆及组织中喹赛多及其脱二氧代谢物 总被引:1,自引:0,他引:1
建立了测定猪血浆及肝脏、肾脏、肌肉等组织中的喹赛多及其代谢物脱二氧喹赛多的高效液相色谱(HPLC)法.血浆样用甲醇沉淀蛋白后离心取上清液进样测定.组织样先用乙腈匀浆,用正己烷脱脂后作HPLC检测.色谱柱为ODS C18柱;流动相血浆样测定为乙腈水(2080),组织样测定为甲醇水(4258),流速为1.0 mL/min;紫外检测波长305 nm.药物工作液质量浓度范围为0.005~0.500 mg/L时,血浆样品及组织样品测定条件下药物质量浓度与响应值均具良好线性关系,相关系数>0.999.血浆中药物质量浓度为0.02、0.10、0.50 mg/L时,喹赛多及脱二氧喹赛多的回收率均大于70%,组织中药物含量为0.05、0.20、1.00μg/g时,肌肉样品的回收率均大于70%,肝脏、肾脏样品则为50%~80%.本试验条件下,喹赛多及其脱二氧代谢物的最低检出质量浓度,血浆样品分别为0.01、0.02mg/L,组织样品2种检测物均为0.025μg/g.测定了工作液3种质量浓度0.01、0.05、0.25 mg/L的仪器精密度,日内相对偏差<8.0%,日间相对偏差<17.0%. 相似文献
119.
Ten sows were during their last month of gestation and first 4 weeks of lactation kept on a low Se ratio (0.014 ppm Se). Their 1-3 days old piglets (n = 108) were divided in 2 groups, the experimental and the control group. Blood samples were taken from the piglets before the age of 3 days. Each of the piglets of the experimental group (n = 54) was treated subcutaneously in connection with the blood sampling with 200 mg Fe+3 as iron dextran and 0,30 mg Se44 as sodium selenite (Pigfer-Se, Orion Corporation Ltd., Orion Pharmaceutics Espoo, Finland). The piglets of the control group (n = 54) were correspondingly treated with 200 Fe+3 as iron dextran. Blood samples were again taken 7, 14 and 28 days after the first sample.The results showed that the mean increase in the number of erythrocytes during the first 7 days was significantly higher in the experimental group than in the control group (p = 0.006). No significant differences between the whole groups could be found in the later blood samples.When some haematological parameters of those of the piglets of the experimental and the control group, which before the age of 3 days had the whole blood Se ^ 55 μg/1 were compared (n = 16 and n = 22 respectively) the mean increase in the number of erythrocytes was found to be significantly higher both at 7 days and 14 days in the low Se piglets of the experimental group than the corresponding means of the control group (p = 0.005 and p = 0.016 respectively). At 28 days the difference between the means was not significant.The weekly mean weight gains of the low Se piglets of the experimental group were consistently higher at the successive weekly weighings than the corresponding means of the control group. 相似文献
120.
花椒树下苜蓿、百脉根和白三叶的光合生理生态特性研究 总被引:2,自引:1,他引:2
为科学指导林草复合中对林下间作牧草的选择,运用美国LI-COR公司制造的LI-6400便携式光合测定系统,研究了白三叶Tritolium repens、苜蓿Medicago sativa和百脉根Lotus corniculatus在林草间作时的光合生理生态特性,探讨三者在林下间作的生态适应性.结果表明:白三叶、苜蓿和百脉根净光合速率(Pn)和气孔导度(Gs)的日变化均为双峰曲线,2个峰值分别出现在11:00和15:00左右.3种植物的Pn与Gs都具有显著相关关系,且叶片温度(Tl)与蒸腾速率(Tr)呈极显著正相关关系. 相似文献