全文获取类型
收费全文 | 6584篇 |
免费 | 323篇 |
国内免费 | 737篇 |
专业分类
林业 | 788篇 |
农学 | 1051篇 |
基础科学 | 606篇 |
1181篇 | |
综合类 | 1843篇 |
农作物 | 287篇 |
水产渔业 | 267篇 |
畜牧兽医 | 844篇 |
园艺 | 247篇 |
植物保护 | 530篇 |
出版年
2024年 | 16篇 |
2023年 | 72篇 |
2022年 | 187篇 |
2021年 | 268篇 |
2020年 | 228篇 |
2019年 | 249篇 |
2018年 | 157篇 |
2017年 | 213篇 |
2016年 | 221篇 |
2015年 | 296篇 |
2014年 | 272篇 |
2013年 | 313篇 |
2012年 | 440篇 |
2011年 | 407篇 |
2010年 | 433篇 |
2009年 | 361篇 |
2008年 | 387篇 |
2007年 | 357篇 |
2006年 | 346篇 |
2005年 | 359篇 |
2004年 | 149篇 |
2003年 | 175篇 |
2002年 | 90篇 |
2001年 | 126篇 |
2000年 | 154篇 |
1999年 | 209篇 |
1998年 | 184篇 |
1997年 | 149篇 |
1996年 | 141篇 |
1995年 | 109篇 |
1994年 | 101篇 |
1993年 | 86篇 |
1992年 | 88篇 |
1991年 | 61篇 |
1990年 | 71篇 |
1989年 | 50篇 |
1988年 | 44篇 |
1987年 | 27篇 |
1986年 | 14篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 9篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
排序方式: 共有7644条查询结果,搜索用时 186 毫秒
941.
942.
为明确南疆新兴特色水果杏李上梨小食心虫Grapholita molesta(Busck)的发生规律和迷向防治效果,于2021—2022年在新疆维吾尔自治区阿克苏地区杏李园采用性诱剂诱集法监测梨小食心虫种群动态,评估性信息素迷向丝对梨小食心虫的防治效果。结果表明,梨小食心虫在阿克苏杏李园1年发生4代,其中越冬代羽化高峰期在4月上中旬,第1代羽化高峰期在5月下旬至6月上旬,第2代羽化高峰期在7月上旬,第3代羽化高峰期在8月上中旬,存在世代重叠现象。2022年农户常规防治区内梨小食心虫的蛀果率为2.46%,性信息素迷向防治区内蛀果率为0.06%; 2021年和2022年使用性信息素迷向丝对梨小食心虫的蛀梢减退率为98.13%和88.65%,2022年的蛀果减退率为98.40%;对不同世代梨小食心虫的雄成虫迷向率在2021年为92.87%~100.00%,雌、雄成虫虫口减退率在2022年为58.75%~81.37%。表明采用梨小食心虫性信息素迷向丝为主的综合防控技术,可有效控制南疆杏李园梨小食心虫的发生与为害。 相似文献
943.
聚合酶链反应(PCR)是检测核酸的强力方法。由于PCR技术简便易行、灵敏度高等优点,该技术被广泛应用于基础研究,成为分子生物学必不可少的研究工具。由于传统的PCR技术存在不能准确定量,且操作过程中易污染而使得假阳性率高等缺点,使其应用受到局限。 相似文献
944.
近年来,高致病性禽流感、高致病性猪蓝耳病等重大动物疫病的发生,折射出了动物卫生监督机构在重大动物疫病防疫监督工作中尚存不足。为此,笔者结合当前重大动物疫病防疫 相似文献
945.
Effects of different forage combinations in total mixed rations on in vitro gas production kinetics,ruminal and milk fatty acid profiles of lactating cows
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sarvvl Bai Zhi‐Jun Cao Bin‐Bin Cao Hong‐Jian Yang Sheng‐Li Li Jian‐Xin Liu 《Animal Science Journal》2018,89(9):1261-1270
This study aimed to determine the effects of different forage combinations on in vitro gas production (GP) kinetics, ruminal and milk fatty acid profiles. Forty‐five lactating cows were randomly arranged into three groups and fed three total mixed rations (TMRs) with different forage combinations: TMR1, 23% alfalfa hay, 7% Chinese wild ryegrass hay and 15% whole corn silage; TMR2, 30% corn stover plus 15% whole corn silage; TMR3, 30% rice straw plus 15% whole corn silage. In vitro dry matter disappearance ranked: TMR1 > TMR2 > TMR3, and highest cumulative GP and asymptotic GP occurred in TMR1 while no difference occurred between TMR2 and TMR3. The average GP rate ranked: TMR1 > TMR2 > TMR3. TMR1 in comparison with TMR2 and TMR3 presented lower rumen contents of acetate and butyrate and greater rumen contents of propionate, valerate, C13:0, C14:0, C15:0, C18:1cis‐9, C18:2n‐6, C18:3n‐3, C20:0 and C22:0 as well as milk C18:2n‐6 and C18:3n‐3 proportions. Transfer efficiencies of C18:2n‐6 and C18:3n‐3 from diet to milk ranked: TMR1 > TMR2 > TMR3. The findings suggest TMRs containing alfalfa hay and Chinese wild ryegrass hay in comparison with corn stover or rice straw improve rumen fermentation and transfer efficiency of C18:2n‐6 and C18:3n‐3. 相似文献
946.
Zhen Chen Dandan Song Jie Yang Xiaoyuan Zuo Zubing Cao Ya Liu Yunhai Zhang 《Animal Science Journal》2018,89(2):316-327
The present study was designed to explore effects of follistatin (FST) on pre‐implantational development of parthenogenetically activated embryos (PAEs) in pigs. First, we investigated the FST messenger RNA expression level and dynamic FST protein expression patterns in porcine oocytes and PAEs. Then, PAEs were placed in embryo culture medium supplemented with 10 ng/mL of FST‐288, FST‐300, and FST‐315. Next, PAEs were cultured with 0, 1, 10 and 100 ng/mL of FST‐315 protein throughout the in vitro culture (IVC) duration. Further, 10 ng/mL of FST‐300 was added from the start of IVC in which PAEs were treated for 30, 48 and 60 h. The results showed that 1 ng/mL FST‐315 could significantly increase the total cell numbers of blastocyst and trophectoderm cell number in PAEs. Exogenous FST‐300 supplementation could significantly promote the early cleavage divisions and improve the blastocyst formation rate of porcine embryos. FST‐300 appeared to affect early embryonic development before activation of the embryonic genome. In all, the study confirmed for the first time that FST plays a role in promoting early embryonic development in pigs, which differed with different FST subtypes. FST‐300 could facilitate the initial cleavage time and improve the blastocyst formation rate, and FST‐315 could improve the blastocyst quality. 相似文献
947.
MiR‐330‐5p negatively regulates ovine preadipocyte differentiation by targeting branched‐chain aminotransferase 2
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Liying Qiao Baojun Li Lifen Cheng Yangyang Pan Jiongjie Jing Ningxian Cao Wenzhong Liu 《Animal Science Journal》2018,89(6):858-867
The differentiation of preadipocytes into adipose tissues is tightly regulated by various factors including microRNAs and cytokines. This article aims to study the effect of miR‐330‐5p on expression of BCAT2 in ovine preadipocytes. Ovine preadipocytes were isolated, and we found that the miR‐330‐5p expression decreased gradually during the early differentiation of ovine preadipocytes, while BCAT2 expression increased. BCAT2 was identified as a direct target of miR‐330‐5p, ectopic expression of miR‐330‐5p could change the expression of both BCAT2 mRNA and protein. Silencing BCAT2 had the same inhibition effects as overexpressing miR‐330‐5p on the preadipocyte differentiation, but overexpressing BCAT2 had the converse effects. Taken together, we demonstrated that miR‐330‐5p is a negative regulator of differentiation by targeting BCAT2, and clarified the role of BCAT2 and miR‐330‐5p during preadipocyte differentiation. 相似文献
948.
949.
推广优质香型超高产两系杂交中籼组合两优6326.介绍两优6326的选育经过、产量表现、特征特性和栽培、繁殖制种技术.两优6326系宣城市农科所用自主选育的优质籼型光温敏核不育系"宣69S"为母本、籼粳交优质淡香型恢复系"中籼WH26"为父本,配组而成的优质香型超高产两系杂交中籼组合.2004年3月通过安徽省农作物品种审定,2007年通过国审(国审稻2007013).两优6326各方面的表现优异,配套高产无公害栽培技术、优质高产繁殖制种技术有助于成果转化.现累计示范、推广面积逾45万hm2.该品种适宜在长江中下游南方稻区作优质一季稻种植,有利于优化粮食品质、促进农民增收. 相似文献
950.
Yongxiao Xu Huihui Chen Ruifang Guan Duxia Cao Qianqian Wu Xueying Yu 《Fibers and Polymers》2016,17(2):181-185
A new fluorescence turn-on chemosensor based on two dipyridylamine groups substituted aurone moiety, 4’-2,2’-dipyridylamine-3-2,2’-dipyridylamine aurone (1), was synthesized. The recognition properties of the compound for cyanide anions and copper ions were investigated. Yellow fluorescence of the compound is almost quenched completely because of the complexation between the compound and copper ions. After the subsequent addition of cyanide anions, fluorescence spectrum is recovered to the original status of the compound owing to the strong bonding ability between cyanide anions and copper ions and the removal of copper ions from the complexes. The recognition also can be observed by naked eye. The compound exhibits a good reversibility and can be used repeatedly to recognize cyanide anions for several times. 相似文献