全文获取类型
收费全文 | 4177篇 |
免费 | 185篇 |
国内免费 | 292篇 |
专业分类
林业 | 173篇 |
农学 | 480篇 |
基础科学 | 40篇 |
168篇 | |
综合类 | 2056篇 |
农作物 | 469篇 |
水产渔业 | 164篇 |
畜牧兽医 | 744篇 |
园艺 | 166篇 |
植物保护 | 194篇 |
出版年
2024年 | 16篇 |
2023年 | 48篇 |
2022年 | 124篇 |
2021年 | 134篇 |
2020年 | 115篇 |
2019年 | 151篇 |
2018年 | 97篇 |
2017年 | 176篇 |
2016年 | 189篇 |
2015年 | 183篇 |
2014年 | 236篇 |
2013年 | 202篇 |
2012年 | 277篇 |
2011年 | 320篇 |
2010年 | 256篇 |
2009年 | 283篇 |
2008年 | 236篇 |
2007年 | 273篇 |
2006年 | 239篇 |
2005年 | 178篇 |
2004年 | 127篇 |
2003年 | 113篇 |
2002年 | 81篇 |
2001年 | 78篇 |
2000年 | 77篇 |
1999年 | 51篇 |
1998年 | 42篇 |
1997年 | 43篇 |
1996年 | 41篇 |
1995年 | 46篇 |
1994年 | 45篇 |
1993年 | 37篇 |
1992年 | 27篇 |
1991年 | 36篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有4654条查询结果,搜索用时 15 毫秒
1.
Antimicrobial peptides are a class of proteins with antibacterial functions. In this study, the anti-lipopolysaccharide factor isoform 3 gene (ALFPm3), encoding an antimicrobial peptide from Penaeus monodon with a super activity was expressed in Chlamydomonas reinhardtii, which would develop a microalga strain that can be used for the antimicrobial peptide production. To construct the expression cluster, namely pH2A-Pm3, the codon optimized ALFPm3 gene was fused with the ble reporter by 2A peptide and inserted into pH124 vector. The glass-bead method was performed to transform pH2A-Pm3 into C. reinhardtii CC-849. In addition to 8 μg/mL zeocin resistance selection, the C. reinhardtii transformants were further confirmed by genomic PCR and RT-PCR. Western blot analysis showed that the C. reinhardtii-derived ALFPm3 (cALFPm3) was successfully expressed in C. reinhardtii transformants and accounted for 0.35% of the total soluble protein (TSP). Furthermore, the results of antibacterial assay revealed that the cALFPm3 could significantly inhibit the growth of a variety of bacteria, including both Gram-negative bacteria and Gram-positive bacteria at a concentration of 0.77 μM. Especially, the inhibition could last longer than 24 h, which performed better than ampicillin. Hence, this study successfully developed a transgenic C. reinhardtii strain, which can produce the active ALFPm3 driven from P. monodon, providing a potential strategy to use C. reinhardtii as the cell factory to produce antimicrobial peptides. 相似文献
2.
百脉根单株产量主要农艺性状的相关和通径分析 总被引:3,自引:0,他引:3
通过对百脉根单株的11个农艺性状的相关分析,结果表明:分枝长度(X2)、分枝节间数(X3)、分枝茎粗(X4)、侧枝数(X6)、侧枝长度(X7)、侧枝节间数(X8)、侧枝茎粗(X9)对单株产量(Y)的作用达到极显著水平,分枝数(X1)、自然高度(X11)与单株产量的相关性达到显著水平,而分枝叶柄长度(X5)、侧枝叶柄长度(X10)则与产量的相关性不显著.通径分析结果表明:各性状对产量的直接效应从大到小依次为:分枝长度(1.121 6)>分枝节间数(0.346 3)>侧枝长度(0.114 6)>分枝数(0.106 4)>分枝茎粗(0.084 6)>侧枝节间数(0.034 2)>侧枝茎粗(0.028 9)>侧枝数(0.021 6)>侧枝叶柄长度(-0.043 6)>分枝叶柄长度(-0.065 4)>自然高度(-0.748 2). 相似文献
3.
Dai Huaguo Song Xiaoling Nanjing Agricultural University Li Jianlong Northeast Forestry University 《林业研究》1993,(2)
Through rearing tests and observations under laboratory conditions,biologicalcharacters and mating behavior of Dahurian casebearer(Coleophora dahurica Flkv.)adultswere studied in this paper.Results discovered that the time of emergense of male adultswas 24h to 36h earlier than that of female adults.The peak of sex pheromone secretion ofthe female adults appeared of 24h to 42h after the emergence.The reaction of male adultson the sex pheromone was most sensitive during 30h to 48h after emerged,so the earlieremergence of the male adults was favorable to mating.The phenomenon of repeatedmating did not exist in female adults,but the male adults could mate for several times,with maximum of 4 times.There was a definite behavioral reaction during the matingperiod of male and female adults,and the certain period of feeding and mating times couldaffect the adults longervity to a certain degree. 相似文献
4.
本文综述了硝酸还原酶与氮素利用的关系及其遗传特性和在作物育种中应用的某些最新进展。氮吸收、利用等性状的生理和遗传特性极其复杂,受环境影响很大,对其进行遗传改良需考虑多种指标。对硝酸还原酶活性(NRA)与品质性状和产量的关系的争论很多,有些研究表明 NRA 可作为品质、产量性状的选择指标,有些则相反。逆境条件下 NRA 的变化非常敏感,NRA 可能与抗逆性有关。 相似文献
5.
6.
7.
Evans EW Harmon BG 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1995,24(4):109-116
Cationic antimicrobial peptides are present throughout the plant and animal kingdoms and bear striking structural and functional similarities across species lines. They provide primitive, nonspecific means of combating a variety of bacteria, fungi, enveloped viruses, and protozoa. Some are also cytotoxic against host cells, including neoplastic cells. Cationic antimicrobial peptides may play various roles in inflammation and tissue repair. Antimicrobial peptides are found in epithelial tissues regularly exposed to microbial attack as well as in cells whose primary function is defense against potential pathogens. They constitute an important part of the nonoxidative antimicrobial arsenal of leukocytes. They are preformed and/or readily synthesized when the cells are stimulated by exposure to pathogens. They exert their effects directly by inserting into membranes of target cells and forming ion channels which increase membrane permeability; however, antimicrobial peptides can also act as opsonins to facilitate phagocytosis. Resistance to defensins is a virulence factor for organisms such as Salmonella sp. The study of cationic antimicrobial peptides is increasing our understanding of innate immunity, inflammation, and the pathogenesis of genetic diseases such as specific granule disease in humans. Therapeutic applications of antimicrobial peptides are currently under investigation. 相似文献
8.
9.
泥炭资源的基本属性、理化性质和开发利用方向 总被引:11,自引:0,他引:11
本文探讨了泥炭资源的资源学属性,总结了泥炭资源的基本理化性质和各种泥炭 资源的开发利用方向对泥炭资源性质的要求。 相似文献
10.
梨果实若干性状的遗传倾向 总被引:5,自引:0,他引:5
以梨12 个杂交组合和138 个栽培品种为试材, 研究几个果实性状的遗传倾向, 结果如下: 栽培品种果实含糖量集中在6 %~9 % , 平均为7. 39 %; 果实含糖量表现为数量性状, 呈正态分布, 杂种后代果实含糖量主要分布在6 %~10 % , 平均为7. 8 % , 遗传传递力平均为90. 8 %。栽培品种含酸量介于0. 08 %~0. 74 % , 平均为0. 238 %; 杂种后代果实含酸量为数量性状, 组合遗传传递力平均为69. 2 %。梨果实挥发性物质共检测出5 种酯类、8 种醇类和乙烯、乙醛、丙酮类共16 种化合物。杂种后代果实中发现了其亲本果实中所没有的戊醇成分。果实肉质性状表现为质量性状, 脆肉对软肉为显性。杂种后代表现为果点变大、密, 果柄变长, 果汁变少, 果皮厚度相当于亲中值。 相似文献