全文获取类型
收费全文 | 5517篇 |
免费 | 512篇 |
国内免费 | 404篇 |
专业分类
林业 | 222篇 |
农学 | 342篇 |
基础科学 | 24篇 |
797篇 | |
综合类 | 1386篇 |
农作物 | 517篇 |
水产渔业 | 1240篇 |
畜牧兽医 | 1627篇 |
园艺 | 167篇 |
植物保护 | 111篇 |
出版年
2024年 | 31篇 |
2023年 | 64篇 |
2022年 | 173篇 |
2021年 | 255篇 |
2020年 | 228篇 |
2019年 | 313篇 |
2018年 | 222篇 |
2017年 | 356篇 |
2016年 | 295篇 |
2015年 | 241篇 |
2014年 | 261篇 |
2013年 | 437篇 |
2012年 | 383篇 |
2011年 | 392篇 |
2010年 | 274篇 |
2009年 | 292篇 |
2008年 | 262篇 |
2007年 | 286篇 |
2006年 | 232篇 |
2005年 | 160篇 |
2004年 | 162篇 |
2003年 | 141篇 |
2002年 | 99篇 |
2001年 | 105篇 |
2000年 | 96篇 |
1999年 | 81篇 |
1998年 | 70篇 |
1997年 | 68篇 |
1996年 | 67篇 |
1995年 | 48篇 |
1994年 | 49篇 |
1993年 | 53篇 |
1992年 | 42篇 |
1991年 | 26篇 |
1990年 | 36篇 |
1989年 | 36篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1981年 | 5篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 5篇 |
1956年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有6433条查询结果,搜索用时 0 毫秒
21.
Kenichi MATSUI Takeshi OHTA Hisayo MORINAGA Tomohiko SASASE Sumiaki FUKUDA Makoto ITO Masatoshi UEDA Naoto OGAWA Katsuhiro MIYAJIMA Mutsuyoshi MATSUSHITA 《Animal Science Journal》2008,79(5):605-613
Spontaneously Diabetic Torii (SDT) fatty rats, made by introducing the fa allele of the Zucker fatty rat into the SDT rat genome, represent a new model of obese type 2 diabetes. SDT fatty fa/fa (SDT fatty) rats exhibit overt obesity, hyperglycemia, and hyperlipidemia from about six weeks of age, and this is associated with hyperphagia by an induced disorder of leptin action. The present study was conducted to elucidate whether suppression of hyperphagia can improve reduce abnormalities in SDT fatty rats. SDT fatty rats were subjected to pair-feeding with SDT fatty +/ + (SDT) rats from 6 to 26 weeks of age, and the effects on metabolic parameters and diabetic complications were assessed. Body weights of the pair-fed rats were similar with those of SDT rats during the experimental period. Improvement of hyperglycemia or hypertriglyceridemia was observed from 8 to 16 or 12 weeks of age in the pair-fed rats, but hypercholesterolemia was not entirely improved during the experimental period. We also examined mRNAs expression in liver, and found that the expression associated with glyconeogenesis, such as glucose-6-phosphatase (G-6-Pase) and phosphoenolpyruvate carboxykinase (PEPCK), tended to decrease in the pair-fed rats, and the mRNA expression of hydroxymethylglutaryl-CoA (HMG-CoA) was elevated. Renal parameters, such as blood urea nitrogen and urinary albumin excretion, were improved in the pair-fed rats. The incidence or progression of diabetic complications, such as renal lesions and cataract, was reduced. In conclusion, suppression of hyperphagia in SDT fatty rats was effective in temporally improving hyperglycemia or hypertriglyceridemia, and reducing the incidence or progression of diabetic complications, but was ineffective in reducing hypercholesterolemia. 相似文献
22.
23.
用排空强饲法对粉浆蛋白粉的常规成分、代谢能及氨基酸利用率进行了测定。结果表明:粉浆蛋白粉干物质中含有粗蛋白质78.4%;代谢能为15.86MJ/kg;赖氨酸5.03%;蛋氨酸0.39%;胱氨酸1.30%;异亮氨酸3.25%;亮氨酸6.92%;精氨酸6.68%:酪氨酸2.34%;苯丙氨酸3.78%:组氨酸1.75%。这些必需氨基酸利用率分别为:92.0%、81.7%、85.2%、90.2%、92.9%、92.4%、90.5%、90.5%和92.1%。其氨基酸利用率介于豆饼与鱼粉之间,是一种值得开发的蛋白质饲料资源。 相似文献
24.
25.
不同淀粉来源对生长猪回肠食糜中微生物氮和氨基酸含量的影响 总被引:1,自引:2,他引:1
本试验旨在研究淀粉消化性能的差异对生长猪回肠食糜中微生物氮和氨基酸含量的影响.试验采用4×4拉丁方设计,选择4头回肠末端安装有简单T瘘管的杜×长×大三元杂交公猪进行消化代谢试验.结果显示,淀粉来源不同其回肠末端消化率存在差异,在生长猪的回肠末端抗性淀粉有83.07%被消化;糯米淀粉被100%消化,玉米和糙米淀粉介于二者之同,分别有97.63%和96.41%被消化;回肠食糜中氮的流量以采食抗性淀粉日粮组最高(为每千克干物质采食量7.44 g),而食糜氮中微生物氮所占比例以采食糯米组最高(为72.8%);各组回肠食糜氨基酸流量中微生物氨基酸所占比率变化范围为25.43%(玉米组)~45.09%(抗性淀粉组),其中抗性淀粉组Asp、Glu、Ser和Lys的比率明显高于玉米组(P<0.05),但Tyr却低于玉米组(P<0.05);糙米组Arg显著高于抗性淀粉组,而Ala和Leu却比抗性淀粉组低(P<0.05);糯米组Ala和Leu也明显较抗性淀粉组低. 相似文献
26.
27.
蛋鸡脂肪肝出血综合征的病因研究进展 总被引:1,自引:0,他引:1
蛋鸡脂肪肝出血综合征(FLHS)是一种代谢性疾病,营养、内分泌、遗传和环境等因素都可影响其发生。日粮中能量过高或蛋白不足是诱发FLHS的主要因素,能量、蛋白来源也影响FLHS的发生。日粮中脂肪酸来源影响FLHS的发生,动物性脂肪较易引起FLHS,适量添加植物油可降低肝脏脂肪含量。雌激素水平升高可引起肝脏脂肪含量增加,与FLHS存在一定的量效关系。甲状腺素和孕酮可降低肝脏脂肪含量,防止出血发生。FLHS易感品系UCD-3蛋鸡肯定了遗传因素对该病的影响。空间不充足或必要活动受限制,导致能量过剩是FLHS发生的重要诱因。肝脏脂肪沉积并不总是引起肝脏出血,脂质过氧化物分解生成大量脂质自由基引起细胞损伤,可能是肝脏脂肪含量升高导致出血的分子机制。 相似文献
28.
29.
《动物营养(英文)》2019,5(3):217-226
Dietary fibers (DF) contain an abundant amount of energy, although the mammalian genome does not encode most of the enzymes required to degrade them. However, a mutual dependence is developed between the host and symbiotic microbes, which has the potential to extract the energy present in these DF. Dietary fibers escape digestion in the foregut and are fermented in the hindgut, producing short-chain fatty acids (SCFA) that alter the microbial ecology in the gastrointestinal tract (GIT) of pigs. Most of the carbohydrates are fermented in the proximal part, allowing protein fermentation in the distal part, resulting in colonic diseases. The structures of resistant starch (RS), arabinoxylan (AX), and β-glucan (βG) are complex; hence, makes their way into the hindgut where these are fermented and provide energy substrates for the colonic epithelial cells. Different microbes have different preferences of binding to different substrates. The RS, AX and βG act as a unique substrate for the microbes and modify the relative composition of the gut microbial community. The granule dimension and surface area of each substrate are different, which influences the penetration capacity of microbes. Arabinose and xylan are 2 different hemicelluloses, but arabinose is substituted on the xylan backbone and occurs in the form of AX. Fermentation of xylan produces butyrate primarily in the small intestine, whereas arabinose produces butyrate in the large intestine. Types of RS and forms of βG also exert beneficial effects by producing different metabolites and modulating the intestinal microbiota. Therefore, it is important to have information of different types of RS, AX and βG and their roles in microbial modulation to get the optimum benefits of fiber fermentation in the gut. This review provides relevant information on the similarities and differences that exist in the way RS, AX, and βG are fermented, and their positive and negative effects on SCFA production and gut microbial ecology of pigs. These insights will help nutritionists to develop dietary strategies that can modulate specific SCFA production and promote beneficial microbiota in the GIT of swine. 相似文献
30.
Arai T. Hashimoto K. Muzutani H. Kawabata T. Sako T. Washizu T. 《Veterinary research communications》1999,23(4):203-209
The plasma concentrations of fructose, glucose, free fatty acids (FFA) and triglycerides (TG) were measured in dogs and cats. Changes in these concentrations were investigated in dogs by an intravenous fructose tolerance test (IVFTT) at a dose of 0.1 g/kg body weight. Fructose concentrations in the plasma of dogs were significantly higher than those of cats. There was no significant difference in plasma glucose concentrations between dogs and cats. Plasma FFA concentrations decreased and TG concentrations increased after feeding in both dogs and cats. During the IVFTT, the plasma fructose concentrations in the dogs increased rapidly to a peak by 2 min and then decreased to half of the peak by 5 min after the administration of fructose. Administration of fructose resulted in an increase in the plasma TG concentrations and reduced plasma FFA concentrations in the dogs. Only 4% of the administered fructose was detected in the urine of dogs following IVFTT. Plasma fructose was considered to be rapidly absorbed and metabolized in both dogs and cats. However, as with glucose metabolism, there appear to be some differences in fructose metabolism between dogs and cats. 相似文献