全文获取类型
收费全文 | 39184篇 |
免费 | 1984篇 |
国内免费 | 4352篇 |
专业分类
林业 | 4346篇 |
农学 | 5835篇 |
基础科学 | 3612篇 |
6423篇 | |
综合类 | 12400篇 |
农作物 | 2242篇 |
水产渔业 | 1446篇 |
畜牧兽医 | 5330篇 |
园艺 | 1405篇 |
植物保护 | 2481篇 |
出版年
2024年 | 172篇 |
2023年 | 544篇 |
2022年 | 1417篇 |
2021年 | 1828篇 |
2020年 | 1705篇 |
2019年 | 1592篇 |
2018年 | 1173篇 |
2017年 | 1619篇 |
2016年 | 1454篇 |
2015年 | 1951篇 |
2014年 | 1827篇 |
2013年 | 2202篇 |
2012年 | 2705篇 |
2011年 | 2836篇 |
2010年 | 2588篇 |
2009年 | 2381篇 |
2008年 | 2163篇 |
2007年 | 2055篇 |
2006年 | 1936篇 |
2005年 | 1754篇 |
2004年 | 809篇 |
2003年 | 707篇 |
2002年 | 565篇 |
2001年 | 599篇 |
2000年 | 672篇 |
1999年 | 835篇 |
1998年 | 768篇 |
1997年 | 658篇 |
1996年 | 593篇 |
1995年 | 634篇 |
1994年 | 503篇 |
1993年 | 434篇 |
1992年 | 454篇 |
1991年 | 340篇 |
1990年 | 300篇 |
1989年 | 205篇 |
1988年 | 166篇 |
1987年 | 125篇 |
1986年 | 64篇 |
1985年 | 34篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 27篇 |
1981年 | 20篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1977年 | 4篇 |
1966年 | 4篇 |
1964年 | 5篇 |
1956年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
AMOSPCR是近年来在布鲁氏菌上尝试使用的一种布鲁氏菌检测方法,可作为布鲁氏菌诊断及菌种类型鉴定的PCR方法,可区分牛种布鲁氏菌1、2、4型,羊种布鲁氏菌、猪种布鲁氏菌、绵羊附睾种布鲁氏菌。本试验用来自国内的疫苗S2,M5及国际上常用的布鲁氏菌疫苗S19,104M试验AMOSPCR的效果,同时对AMOSPCR扩增条带进行测序。结果表明,除国内布鲁氏菌S19检测结果与国外菌株不同外,其余的几种疫苗株都得到典型的特征性条带。同时测序结果也表明各种属条带无交叉反应,为今后国内诊断布鲁氏菌病诊断方法研究指出一个方向。 相似文献
962.
963.
Kang JH Yang MP 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2008,22(5):1166-1173
Background: The use of soybean oil-based lipid emulsion (SO-based LE) in parenteral nutrition has been reported to impair neutrophil functions in humans and rodents. As yet, little is understood about the effects of SO-based LE on canine immune responses.
Hypothesis: A short-term infusion with SO-based LE affects the phagocytic responses of canine peripheral blood polymorphonuclear neutrophilic leukocytes (PMNs).
Animals: Twenty-four healthy Beagle dogs.
Methods: Experimental study. Dogs were randomly assigned into groups of six and administered a 2-hour IV infusion with 0.9% NaCl solution or sufficient SO-based LE (INTRALIPOS 20%) to supply 40, 100, and 200% of the basal energy requirement (BER). PMN functions were determined after collecting blood samples before, immediately after, and 24 hours after the infusion.
Results: None of the treatments significantly affected the phagocytic capacity of PMNs or circulating leukocyte numbers. The infusion providing 200% of BERs significantly reduced PMN oxidative burst activity, filamentous actin polymerization, and Cdc42 Rho guanosine triphosphatase activity immediately after its delivery. However, these functions were restored to pre-infusion values 24 hours after the infusion. The lower calorie infusions did not have these effects.
Conclusions and Clinical Importance: These results suggest that short-term infusions with a supraphysiological dose of SO-based LE may decrease the immune functions of canine PMNs. However, more long-term studies will be needed to extrapolate the effect of SO-based LE with clinically relevant doses in a practical situation. 相似文献
Hypothesis: A short-term infusion with SO-based LE affects the phagocytic responses of canine peripheral blood polymorphonuclear neutrophilic leukocytes (PMNs).
Animals: Twenty-four healthy Beagle dogs.
Methods: Experimental study. Dogs were randomly assigned into groups of six and administered a 2-hour IV infusion with 0.9% NaCl solution or sufficient SO-based LE (INTRALIPOS 20%) to supply 40, 100, and 200% of the basal energy requirement (BER). PMN functions were determined after collecting blood samples before, immediately after, and 24 hours after the infusion.
Results: None of the treatments significantly affected the phagocytic capacity of PMNs or circulating leukocyte numbers. The infusion providing 200% of BERs significantly reduced PMN oxidative burst activity, filamentous actin polymerization, and Cdc42 Rho guanosine triphosphatase activity immediately after its delivery. However, these functions were restored to pre-infusion values 24 hours after the infusion. The lower calorie infusions did not have these effects.
Conclusions and Clinical Importance: These results suggest that short-term infusions with a supraphysiological dose of SO-based LE may decrease the immune functions of canine PMNs. However, more long-term studies will be needed to extrapolate the effect of SO-based LE with clinically relevant doses in a practical situation. 相似文献
964.
2007年10月7日至11月6日,农业部外经中心组织了中加动物健康推广服务项目赴加拿大培训考察活动。培训考察团由农业部兽医局和内蒙、甘肃、陕西、新疆、重庆、四川农 相似文献
965.
966.
W. Sun H. Chang K. Tsunoda H.H. Musa Z.P. Yang Y.H. Ma W.J. Guan 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2010,127(4):308-317
The genetic diversity and phylogenetic survey of native sheep breeds in the eastern and southern Central Asia were assessed in the present study. The clustering, principal components, structure and F statistics all demonstrate that the native sheep breeds in these regions be classified into two genetic groups: Mongolia‐Tibetan sheep group and South‐Southeast Asia sheep group. The Mongolia sheep group and the Tibetan sheep group had a certain degree of gene communication from the ancient times. In the present study we demonstrated that the Chinese native sheep populations belonged to Mongolia‐Tibetan sheep group. However, the relationships among the sheep populations in Mongolia sheep group in China were not closely related to the geographical distance among sheep populations. 相似文献
967.
用聚丙烯酰胺凝胶圆盘电泳分离黑白花奶牛血清AKP同功酶酶谱及鉴定其组织来源。健康牛血清有5条酶带,以其泳动速率分为快(SF)、慢-1、慢-2、慢-3和慢-4(SS-1~4)。所有血清中除有主带SF和SS-1外,尚有1~3条慢带。骨只有一条泳动速率与血清主带SS-1相同的带,被认为是SS-1的来源。肝有2条泳动较快的带(LF-1和LF-2)和一条慢带LS。其中LF-1为窄的黄带,血清无对应带;LF-2与血清主带SF相对应,为SF的来源;LS为一条与SS-1相对应的浅而宽的带,为血液污染所致。小肠有3条窄的快带(IF-1~3)和一条宽的慢带(IS),慢带与比它稍快的骨带有部分重合出现于部分血清中,而3条快带未在血清出现。各种组织的AKP有不同的热稳定性。总之,血清主带SF和SS-1分别来源于肝和骨,SS-2来源于小肠,SS-3和SS-4在所分析的组织中无相应酶带。本研究较详细地描述了一种被改进的电泳方法,使其易于应用。 相似文献
968.
Effects of apple pomace‐mixed silage on growth performance and meat quality in finishing pigs 下载免费PDF全文
Jiachen Fang Yang Cao Masatoshi Matsuzaki Hiroyuki Suzuki Hirofumi Kimura 《Animal Science Journal》2016,87(12):1516-1521
We measured the growth performance and meat quality of 10 crossbred (Yorkshire × Duroc × Landrace) neutered male pigs to evaluate the effects of apple pomace‐mixed silage (APMS). The pigs were divided into two groups and were respectively fed the control feed and the AMPS ad libitum during the experiment. No difference was found in the finished body weight, average daily gain, carcass weight, back fat thickness or dressing ratio between the control and the AMPS treatments, but average dairy feed intake (dry matter) was significantly lower and feed efficiency was significantly higher using the APMS treatment (P < 0.05). With regard to meat quality, the APMS increased the moisture content but decreased the water holding capacity (P < 0.05) compared with the control treatment. Furthermore, the APMS affected the fatty acid composition of the back fat by increasing linoleic acid (C18:2n6), linolenic acid (C18:3) and arachidic acid (C20:0) levels, while decreasing palmitic acid (C16:0), palmitoleic acid (C16:1) and heptadecenoic acid (C17:1) levels, compared with the control treatment. These results indicate that feeding fermented apple pomace to finishing pigs increases the feed efficiency and affects the meat quality and fatty acid composition of back fat. 相似文献
969.
为快速鉴别诊断猪流行性腹泻病毒(PEDV)、猪传染性胃肠炎病毒(TGEV)、猪轮状病毒(PoRV)和猪嵴病毒(PKV),根据PEDV的M基因、TGEV的N基因、PoRV的VP6基因和PKV的3D基因序列设计4对特异性引物,通过PCR扩增目的片段并构建重组质粒,建立了一种可同时检测4种病毒的RT-PCR诊断方法,该方法可特异性扩增这4种病毒的相应片段,而对猪瘟病毒(CSFV)、猪圆环病毒2型(PCV-2)、猪繁殖与呼吸综合征病毒(PRRSV)、猪伪狂犬病病毒(PRV)均无扩增,最低检出量分别为1.33×10^4、1.33×10^3、1.33×10^4、1.33×10^5copies/μL。应用该方法对临床55份猪腹泻样品进行检测,结果检测出14份PEDV、1份PoRV和27份PKV,未检出TGEV,其中PEDV和PKV混合感染9份。上述结果表明,建立的多重RT-PCR检测方法快速、特异、敏感,可用于以上4种腹泻病毒的临床检测和流行病学调查。 相似文献
970.
This study was conducted to investigate the effects of compound p1ant nutrients (CPN) on rumen fermentation parameters, rumen microbiota and fatty acid composition of longissimus dorsi musc1e in finishing sma11 tai1 Han sheep. Sixteen 4-month-o1d finishing sma11 tai1 Han sheep with an initia1 body weight (BW) of (24.18±0.31) kg were random1y divided into two groups, name1y, with 8 rep1icates per group and 1 sheep per rep1icate. The sheep in the contro1 group were fed a basa1 diet, whereas the sheep of the contro1 group (CPN group) was fed the basa1 diet supp1ementation with 3‰ CPN. The experiment 1asted for 97 days after 7 days adaption. The resu1ts showed as fo11ows: compared with the contro1 group, 1) adding CPN decreased the concentration of ammonia nitrogen (NH3-N) (P<0.05); 2) CPN supp1ementation affected beta diversity of rumen microbiota; 3) the re1ative abundance of Acidobacteriota, Erysipe1otrichaceae_UCG-002, Lactobacillus, and Megasphaera were enhanced by adding CPN (P<0.05), whereas, the re1ative abundance of Bacteroidetes and Prevotella was 1ower (P<0.05); 4) the supp1ementation of CPN had no significant effect on fatty acid composition of longissimus dorsi musc1e of fattening sma11-tai1ed Han sheep (P>0.05); 5) the contents of tota1 MUFA, C18:1n9c, C14:1, C16:1, C18:2n6c, C18:3n3 and n-3PUFA in the longissimus dorsi musc1e were corre1ated with the re1ative abundance of Megasphaera, Erysipe1otrichaceae_UCG-002, Succiniclasticum and Ruminococcus (P<0.05). In conc1usion, CPN can regu1ate the rumen microbiota structure and reduce the rumen NH3-N concentration of fattening sma11-tai1ed Han sheep. In production practice, CPN can be used as a rumen eco1ogica1 regu1ator. © 2023 Authors. All rights reserved. 相似文献