全文获取类型
收费全文 | 5815篇 |
免费 | 236篇 |
国内免费 | 602篇 |
专业分类
林业 | 662篇 |
农学 | 956篇 |
基础科学 | 432篇 |
885篇 | |
综合类 | 1940篇 |
农作物 | 273篇 |
水产渔业 | 208篇 |
畜牧兽医 | 835篇 |
园艺 | 225篇 |
植物保护 | 237篇 |
出版年
2024年 | 10篇 |
2023年 | 69篇 |
2022年 | 152篇 |
2021年 | 237篇 |
2020年 | 216篇 |
2019年 | 210篇 |
2018年 | 166篇 |
2017年 | 213篇 |
2016年 | 197篇 |
2015年 | 256篇 |
2014年 | 247篇 |
2013年 | 291篇 |
2012年 | 403篇 |
2011年 | 377篇 |
2010年 | 382篇 |
2009年 | 315篇 |
2008年 | 302篇 |
2007年 | 322篇 |
2006年 | 304篇 |
2005年 | 317篇 |
2004年 | 156篇 |
2003年 | 132篇 |
2002年 | 103篇 |
2001年 | 135篇 |
2000年 | 127篇 |
1999年 | 136篇 |
1998年 | 103篇 |
1997年 | 105篇 |
1996年 | 95篇 |
1995年 | 78篇 |
1994年 | 95篇 |
1993年 | 80篇 |
1992年 | 59篇 |
1991年 | 70篇 |
1990年 | 59篇 |
1989年 | 47篇 |
1988年 | 43篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
排序方式: 共有6653条查询结果,搜索用时 62 毫秒
31.
32.
Qiyan Xiong Yanna Wei Zhixin Feng Yuan Gan Zhanjun Liu Maojun Liu Fangfang Bai Guoqing Shao 《Veterinary journal (London, England : 1997)》2014,199(2):268-274
An attenuated Mycoplasma hyopneumoniae vaccine that requires intrathoracic administration is commercially available for use against mycoplasmal pneumonia in China. Given the limitations of such a route of administration, this study was undertaken to assess the capacity of an ISCOM-matrix adjuvant to enhance immunogenicity following intramuscular use. Immune responses in pigs following vaccination and subsequent intra-tracheal bacterial inoculation were examined using lymphocyte proliferation, serology and mucosal IgA in both nasal and saliva swabs.Vaccination induced clear lymphocyte proliferation, but only slight serum antibody responses although these were significantly increased following experimental infection. Mucosal IgA was not detected in either nasal or salivary secretions. Following bacterial challenge, animals vaccinated with the adjuvant-containing live vaccine exhibited less severe pulmonary lesions (median score 3.67) than unvaccinated pigs (median score 13.58). The degree of ciliary loss on the respiratory tract surface was reduced in vaccinated pigs compared with experimentally infected controls. The findings indicated that the adjuvant vaccine administered IM provided protection against experimentally induced mycoplasmal pneumonia and could have commercial potential. 相似文献
33.
Jiewen Guan Maria Chan Brian W. Brooks Elizabeth Rohonczy 《Canadian journal of veterinary research》2015,79(4):347-350
Avian influenza outbreaks have occurred during winter months, and effective disinfection of poultry premises at freezing temperatures is needed. The commercial disinfectants Virkon and Accel, supplemented with an antifreeze agent [propylene glycol (PG), methanol (MeOH), or calcium chloride (CaCl2)], were evaluated for their effectiveness in killing avian influenza virus (AIV) at −20°C or 21°C. An AIV suspension was applied to stainless steel disks, air-dried, and covered with a disinfectant or antifreeze agent for 5 to 30 min. Virkon (2%) and Accel (6.25%) with 30% PG, 20% MeOH, or 20% CaCl2 inactivated 6 log10 AIV within 5 min at −20°C and 21°C. At these temperatures PG and MeOH alone did not kill AIV, but the 20% CaCl2 solution alone inactivated 5 log10 AIV within 10 min. The results suggested that CaCl2 is potentially useful to enhance the effectiveness of disinfection of poultry facilities after outbreaks of AIV infection in warm and cold seasons. 相似文献
34.
35.
36.
Density of steam-flaked sorghum grain, roughage level, and feeding regimen for feedlot steers. 总被引:3,自引:0,他引:3
Two hundred fifty-two steers (366 kg) were assigned to a 3 x 2 x 2 factorial arrangement of three densities of steam-flaked sorghum grain (bulk [flake] density of 437, 360, and 283 g/liter, B34, B28, and B22, respectively), two roughage levels (9 [R9] and 18% [R18]) and two feeding strategies (ad libitum [AD] or multiple of maintenance [MM], 2.3, 2.5, and 2.7 MM for wk 1, 2, and 3, and 2.9 MM thereafter). Steers fed R18-AD gained faster than steers fed R18-MM (1.59 vs 1.52 kg/d, P = .10); for R9 diets, no difference (P greater than .25) was found between steers fed AD and MM (interaction, P = .07). Flake density did not affect ADG (1.53 kg, P greater than .2). Dry matter intake decreased (9.8, 9.3, and 9.0 kg/d, linear, P less than .001) and gain efficiency (G/DMI, kg of gain/100 kg of DMI) increased (15.7, 16.5, and 16.9, linear, P less than .001; quadratic, P = .19) as processing degree increased (B34 to B22). Percentage of choice carcasses for B34 (67.0%) was higher (linear, P = .05) than for B28 (51.9%) and B22 (52.3%). Fecal starch and pH were 10.8, 5.7, and 4.0%, and 6.11, 6.23, and 6.37 for B34, B28, and B22, respectively (linear, P less than .001). The correlation between fecal starch and pH was -.51 (P less than .001, n = 252). Enzymatic glucose release, in vitro 6-h gas production, microbial protein synthesis, and protein degradability were 375, 483, and 559 mg/g; 24.7, 28.2, and 31.1 ml/.2 g; 6.15, 6.88, and 7.84 g/100g; and 61.4, 56.6, and 42.2% for B34, B28, and B22, respectively (linear, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
37.
秸秆氨化与精料添加对羔羊生产性能的影响 总被引:3,自引:0,他引:3
本文报道了小麦秸氨化与精料添加对羔羊生产性能影响的研究结果。麦秸氨化提高了羔羊日增重、秸秆与日粮进食量及精料转化效率,但其提高幅度随日粮精料添加量的提高而减小。提高日粮精料添加水平,羔羊日增重与日粮绝对进食量提高,但精料转化效率在氨化与未氨化组呈不同规律变化:未氨化组持续提高,氨化组呈二次曲线规律变化,且“精料/增重”比最低的日粮精料水平为45%。 相似文献
38.
39.
40.
唐村镇位于淳安西北部,地域面积83km2,辖26个行政村,总人口1.5万,人均耕地0.022hm2,是一个人多地少,资源相对贫乏,经济欠发达乡镇.蚕桑收入占农业总收入的20%,蚕桑生产如今已成为该镇农村经济的主导产业,是农民家庭经济收入主要来源之一.2004年全镇桑园面积454hm2,饲养蚕种9 538张,生产蚕茧425.5t,蚕茧产值836.8万元.蚕种饲养量比2001年增122%,蚕茧产量增163%,蚕桑收入增166%,同时是2000年的3倍.2003年、2004年连续2年获县政府表彰奖励.近3年来唐村镇蚕桑产业能取得如此成效,有以下的主要经验和做法. 相似文献