全文获取类型
收费全文 | 17807篇 |
免费 | 1222篇 |
国内免费 | 1656篇 |
专业分类
林业 | 1257篇 |
农学 | 869篇 |
基础科学 | 709篇 |
1886篇 | |
综合类 | 9216篇 |
农作物 | 1399篇 |
水产渔业 | 856篇 |
畜牧兽医 | 2355篇 |
园艺 | 1357篇 |
植物保护 | 781篇 |
出版年
2024年 | 146篇 |
2023年 | 399篇 |
2022年 | 797篇 |
2021年 | 818篇 |
2020年 | 726篇 |
2019年 | 711篇 |
2018年 | 591篇 |
2017年 | 854篇 |
2016年 | 596篇 |
2015年 | 854篇 |
2014年 | 888篇 |
2013年 | 1088篇 |
2012年 | 1577篇 |
2011年 | 1594篇 |
2010年 | 1509篇 |
2009年 | 1266篇 |
2008年 | 1347篇 |
2007年 | 1179篇 |
2006年 | 1004篇 |
2005年 | 817篇 |
2004年 | 468篇 |
2003年 | 334篇 |
2002年 | 321篇 |
2001年 | 304篇 |
2000年 | 260篇 |
1999年 | 95篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 17篇 |
1989年 | 4篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 6篇 |
1965年 | 1篇 |
1962年 | 5篇 |
1956年 | 6篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
81.
This experiment was conducted to investigate the liver-protective effect of Chinese herbal compound probiotics (CHCP) on acute liver injury layers.One hundred and eight 1 day old hens were divided into 4 groups with 3 replicates in each group and 9 layers per replicate in trial 1.The layers in model groups Ⅰ to Ⅲ were gavaged with 10% (V/V) soybean oil solution of carbon tetrachloride (SCCl4) according to 1,2 and 4 mL/(kg·BW) at 14,28 and 35 d,respectively.The layers in control group were gavaged with 2 mL/(kg·BW) soybean oil.In trial 2,sixty 1 d layers were divided into 5 groups:Control group (soybean oil),model control group(SCCl4)and low-dose,middle-dose and high-dose CHCP group (SCCl4+1‰ CHCP,SCCl4+2‰ CHCP and SCCl4+4‰ CHCP respectively).CHCP were used by drinking water since 7 days.SCCl4 were gavaged according to 2 mL/(kg·BW) at 14 and 28 d.The results showed as follows:The model of layers liver damage could be built by intragastric administration of 2 mL/(kg·BW) 10%(V/V) SCCl4 at 14,28 d respectively,with the signs of hepatic steatosis,severe vacuolar degeneration,nuclear condensation and necrosis.Compared to the model control group,the serum AST levels in low,medium and high dose CHCP groups were decreased by 4.35% (P > 0.05),7.57% (P > 0.05) and 9.79% (P < 0.05),the serum ALT levels in medium and high dose CHCP groups were decreased by 34.92% (P < 0.01),36.51% (P < 0.01),the serum total bilirubin content in medium and high dose CHCP groups were decreased by 25.49% (P < 0.01),27.45% (P < 0.01).The liver cell congestion was reduced to varying degrees in different dose CHCP groups,and the liver cell had no vacuoles,arranged in neat rows,abundant cytoplasm and uniform in different dose CHCP groups.In conclusion,2‰,4‰ CHCP could reduce hepatocyte necrosis,decrease the serum activities of ALT,AST and total bilirubin levels,and had protective effect on hepatic injury induced by SCCl4. 相似文献
82.
miR-106b-5p靶向KLF4调控山羊肌内前体脂肪细胞分化 总被引:1,自引:1,他引:0
旨在明确miR-106b-5p对山羊肌内前体脂肪细胞分化的影响,并确定这种作用是通过靶向KLF4来实现的。本研究利用实时荧光定量PCR (quantitative real-time PCR,qRT-PCR)技术检测miR-106b-5p在山羊肌内前体脂肪细胞分化过程中的表达模式,通过脂质体转染技术将miR-106b-5p mimic和miR-106b-5p inhibitor转入体外培养的山羊肌内前体脂肪细胞,油红O染色法从形态学验证miR-106b-5p对脂肪细胞中脂滴积聚的影响,qRT-PCR检测预测的靶标基因KLF4和脂肪分化标志基因的表达情况,利用双荧光素酶报告系统鉴定miR-106b-5p与KLF4的靶标关系。qRT-PCR结果显示,miR-106b-5p在山羊肌内前体脂肪细胞诱导分化第3天时表达量最高。在山羊肌内脂肪细胞中干扰miR-106b-5p后油红O染色显示脂滴聚积减少,过表达miR-106b-5p后脂滴聚积增加。在山羊肌内前体脂肪细胞中转染miR-106b-5p inhibitor后PPARγ表达量显著降低(P<0.05),而KLF4表达量极显著升高(P<0.01);转染miR-106b-5p mimic后LPL和PPARγ表达量极显著升高(P<0.01)。荧光素酶活性试验结果显示,过表达miR-106b-5p可显著抑制KLF4荧光活性。miR-106b-5p通过靶向并负调节KLF4的表达促进山羊肌内脂肪细胞分化。 相似文献
83.
84.
85.
为构建猪链球菌(Streptococcus suis)蛋白表面展示系统,本研究通过序列分析,确定猪链球菌的LPxTG蛋白及其信号肽(SP)和胞壁锚定基序(CWA),通过PCR扩增Peno-SP、GFP、CWA的DNA片段并融合,构建强启动子Peno控制表达编码SP-GFP-CWA融合蛋白的DNA片段,将该重组DNA片段连接pSET2载体,获得蛋白表面展示质粒,转化猪链球菌,构建得到以GFP为报告蛋白的猪链球菌蛋白表面展示系统。结果显示,利用猪链球菌的10个LPxTG蛋白及其SP和CWA序列,构建了10个含有Peno-SP-GFP-CWA融合片段的重组pSET2表面蛋白展示质粒pSsPSD1至pSsPSD10,分别转化猪链球菌05ZYH33,PCR鉴定显示其中7个转化猪链球菌。采用western blot初步检测其展示蛋白,结果显示,7个转化阳性菌株均能有效表达GFP蛋白,以成熟GFP条带为指标,均表现出了一定的外源GFP表面展示水平,分别命名为SsPSD1、SsPSD2、SsPSD4、SsPSD7-SsPSD10,其中SsPSD1、SsPSD4、SsPSD8和SsPSD9表面展示水平相对较好,在猪链球菌表面展示外源蛋白方面具有很好的潜力。本研究首次尝试建立猪链球菌蛋白表面展示系统,为猪链球菌表面递呈外源蛋白或抗原提供了新的策略。 相似文献
86.
Xiang-dong LUO Jian LIU Jun ZHAO Liang-fang DAI Ya-ling CHEN Ling ZHANG Fantao ZHANG Biao-lin HU Jian-kun XIE 《农业科学学报》2018,17(2):265-275
Cold stress is a major problem in rice production. To rapidly identify genes for cold tolerance in Dongxiang wild rice(DWR, Oryza rufipogon Griff.), sequencing-based bulked segregant analysis of QTL-seq method was used to resequence the extremely resistant(R) and susceptible(S) bulks of a backcross inbred lines(BILs) population(derived from Oryza sativa×O. rufipogon) and their parents. Single nucleotide polymorphisms(SNP)-index graphs and corresponding Δ(SNPindex) graphs(at 99 and 95% confidence levels) for R-and S-bulks detected a total of 2 609 candidate SNPs, including 58 candidate cold-tolerance genes. Quantitative real-time PCR analysis revealed that 5 out of the 58 candidate genes had significant differences in expression between O. sativa and O. rufipogon. Structural variation and functional annotations of the 5 candidate genes were also analyzed, and allowed us to identify 2 insertion-deletion(InDel) markers(12-7 and 12-16) that were linked with candidate genes on chromosome 12 in DWR. These results are helpful for cloning and using cold tolerance genes from common wild rice in cultivated rice. 相似文献
87.
88.
89.
Teats number is one of the most important reproductive traits,and closely related to the economic benefit in pig industry.In order to reveal the underlying genetics of left teats number,right teats number and total teats number traits,a genome-wide association study(GWAS)was performed.Samples of DNA were collected to genotyping for 22 Kele pigs using the Illumina Porcine SNP 60K Chip.The GWAS was performed using a mixed-effects model and linear regression approach.When a genome-wide threshold was determined using the Bonferroni method(P<2.06E-5),4 single nucleotide polymorphism(SNP)markers were potentially associated with left teats number,right teats number and total teat number.However,3 SNPs were significant associated and 18 SNPs were potentially associated in chromosomes level.304 Ensembl genes were retrieved around 1 cM of the associated SNPs.The candidate genes in Wnt and Fgf signaling pathway(BTRC,FGF5,FGF8,BMP3,RASGEF1B and HMGB3)might have effect on target traits.These results provided valuable information about the selective breeding for Kele pigs. 相似文献
90.
中国马铃薯发展历史、育种现状及发展建议 总被引:2,自引:0,他引:2
马铃薯是我国仅次于水稻、小麦和玉米的第四大粮食作物,栽培面积近600万hm~2,年产量约9 000万t,居世界首位。中国农业部预计今后20 a间,我国需增产500亿kg粮食保障人民生活和社会发展的基本需要,马铃薯的贡献率将达到50%。本文综述了中国马铃薯的起源和发展,主要经历了3个发展阶段;系统回顾了中国马铃薯的育种现状、各个时期的主要育种目标及品种应用状况,在此基础上,为中国马铃薯产业健康发展提出几点设想和建议。 相似文献