全文获取类型
收费全文 | 170篇 |
免费 | 33篇 |
国内免费 | 24篇 |
专业分类
林业 | 6篇 |
农学 | 17篇 |
基础科学 | 8篇 |
14篇 | |
综合类 | 96篇 |
农作物 | 13篇 |
水产渔业 | 5篇 |
畜牧兽医 | 53篇 |
园艺 | 8篇 |
植物保护 | 7篇 |
出版年
2023年 | 7篇 |
2022年 | 23篇 |
2021年 | 20篇 |
2020年 | 19篇 |
2019年 | 23篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 14篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 8篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2007年 | 5篇 |
2006年 | 4篇 |
2004年 | 5篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 0 毫秒
101.
102.
Antonina Klimenko Robin Huber Laurence Marcourt Estelle Chardonnens Alexey Koval Yuri S. Khotimchenko Emerson Ferreira Queiroz Jean-Luc Wolfender Vladimir L. Katanaev 《Marine drugs》2021,19(1)
Triple-negative breast cancer (TNBC) represents the deadliest form of gynecological tumors currently lacking targeted therapies. The ethanol extract of the North Pacific brittle star Ophiura sarsii presented promising anti-TNBC activities. After elimination of the inert material, the active extract was submitted to a bioguided isolation approach using high-resolution semipreparative HPLC-UV, resulting in one-step isolation of an unusual porphyrin derivative possessing strong cytotoxic activity. HRMS and 2D NMR resulted in the structure elucidation of the compound as (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid. Never identified before in Ophiuroidea, porphyrins have found broad applications as photosensitizers in the anticancer photodynamic therapy. The simple isolation of a cytotoxic porphyrin from an abundant brittle star species we describe here may pave the way for novel natural-based developments of targeted anti-cancer therapies. 相似文献
103.
以耐密抗倒性不同的品种(稀植大穗品种JK 518和JK 519、耐密抗倒品种XY335和CS 1;中等耐密品种ND 108)为材料,设5个密度处理,研究玉米茎秆的穿刺强度(RPS)的变化特点及其对群体种植密度的响应。结果表明玉米茎秆穿刺强度随生育期递进而增强,不同耐密性品种间随种植密度变化有较大差异。茎秆基部节间的穿刺强度随群体密度增加呈线性递减。茎秆节间RPS随着节位的上升而呈二次函数递减;不同耐密性品种间RPS以抽雄-吐丝期差异明显,以穗位以下节间,尤其第3~6节间表现差异较大。玉米抽雄前茎壁增厚早、 相似文献
104.
目标起始密码子多态性(SCoT)分子标记技术在花生属中的应用 总被引:5,自引:0,他引:5
花生属分子标记领域的研究远落后于其他物种,而栽培种花生因其遗传基础狭窄,用大多数分子标记技术都难以检测到丰富的分子标记,因此限制了花生属野生种在改良花生栽培种方面的利用以及建立花生分子标记辅助育种技术体系。本文分别对花生属4个区组的16份种质资源和8份花生栽培种资源采用与功能基因相关的SCoT分子标记技术研究了花生属种间和栽培种内遗传多样性和亲缘关系。23条SCoT引物在花生属试材基因组中的扩增位点共194个,其中多态性位点130个,多态性达67.01%,通过聚类分析研究了它们之间的亲缘关系;在栽培种内筛选出19条多态性引物,在8份试材基因组中扩增位点198个,其中多态性位点67个,多态性为33.84%,表明SCoT分子标记技术能在花生栽培种内检测出一定程度的DNA多态性。 相似文献
105.
LAN Xin XIAO Shu ZHANG Jia-wei CHENG Xiao-feng ZHAO Jia-yi WANG Hua-dong LU Da-xiang ZHU Li-hong 《园艺学报》2019,35(5):851-857
AIM: To establish the mouse model of sepsis-associated encephalopathy (SAE) and the preliminary research of cognitive dysfunction in this model. METHODS: SPF male C57BL/6J mice of 8~10 weeks old were selected. The first part of the experiment divided the mice into 4 groups randomly, namely control group, cecal ligation and puncture (CLP)1 group and CLP2 group (CLP was performed with 7 and 12 syringe needle respectively). The mice in sham operation group were only laparotomy. In the second part of the experiment, the mice were randomly divided into control group, sham operation group and CLP group. The Kaplan-Meier method was used to analyze the postoperative survival rate of the mice in the first part experiment. The neurobehavioral scores were used to evaluate the neurobehavioral changes of the mice. The Morris water maze test and the passive avoidance experiment were used to detect the changes of cognitive memory function in the mice. The pole test and the wire suspension test were used to test the motor coordination of the mice. The serum levels of prostaglandin E2 (PGE2) were measured by ELISA. RESULTS: In the first part of the experiment, the CLP mice showed obvious symptoms such as lethargy, piloerection, chills and anorexia. The 48 h mortality in CLP1 group and CLP2 group were 20% and 30% respectively. In the 2 parts of the experiments, the neurobehavioral scores of the CLP mice were significantly lower than those in control group and the sham operation group (P<0.01). In CLP mice, the escape latency time of the Morris water maze was significantly prolonged (P<0.01), the target quadrant dwell time and the number of crossing platforms were decreased (P<0.01), the scores in the suspension experiment and the pole test were significantly reduced (P<0.01), the activity of the mice was decreased or even did not enter the darkroom in the step-through test (P<0.05). In the second part of the experiment, the serum level of PGE2 in the mice after CLP was significantly increased (P<0.01). CONCLUSION: A stable mouse model of sepsis-associated encephalopathy is successfully established by cecal ligation and puncture with 12 syringe needle. The SAE mouse model established by this method is useful for investigating the learning and memory cognitive dysfunction. 相似文献
106.
探索数字减影血管造影(DSA)定位引导技术在恒河猴脑脊液动态采集中的应用。将28只恒河猴随机均分为2组,经左前肢静脉推注30g/L戊巴比妥钠溶液全麻后,常规剔除背部脊柱周围体毛并消毒;试验组在DSA定向引导技术下行腰椎间隙穿刺蛛网膜下腔采集脑脊液,结果14只全部穿刺成功,穿刺后均有脑脊液从穿刺针中流出;对照组直接行腰椎间隙穿刺蛛网膜下腔,8只穿刺成功,6只穿刺失败,后经DSA定位引导技术调整针尖方向与位置,完成穿刺,采集到脑脊液;28只恒河猴穿刺成功后均在DSA定位引导下将硬膜外麻醉导管经蛛网膜下腔至枕大池,置泵于腰背部,通过所置的泵可实现恒河猴在清醒、全生理状态下对脑脊液进行动态多次采集,快速省时,由于采样导管置于枕大池,采集到的脑脊液无色透明、样品质量有保证,易于满足检验需要,具有一定的实用价值。 相似文献
107.
Marker-assisted selection has become an integral component of many crop breeding programs in both the private public sectors throughout the world.…… 《分子植物育种》2007,5(2):251-251
Marker-assisted selection has become an integral component of many crop breeding programs in both the private and public sectors throughout the world. Various markers, such as RFLP, RAPD, AFLP and SSR are being used by the crop breeding community. The advent of high throughput sequencing technology has generated an enormous amount of DNA sequence information for the genomes of many species of economic importance. This includes the draft genome sequences of two subspecies of rice, one of the most important food crops of the world and more than 40 million expressed sequence tags (EST) in the public databases. This wealth of information provides the opportunity to develop novel approaches to discover markers such as single nucleotide polymorphism (SNP) and targeted local lesions in genomes (TILLING) techniques, which are being applied to different crops at a fast pace. The TRAP (targeted region amplification polymorphism) marker technique is a fairly new, relatively high throughput, persuasively reliable, and broadly applicable fingerprinting technique. TRAP harnesses existing sequence information and leverages bioinformatics tools to design fixed primers against known sequences of annotated ESTs, 相似文献
108.
James Lever Florian Kreuder Jason Henry Andrew Hung Pierre-Marie Allard Robert Brklja
a Colin Rix Aya C. Taki Robin B. Gasser Jan Kaslin Donald Wlodkowic Jean-Luc Wolfender Sylvia Urban 《Marine drugs》2022,20(9)
Many targeted natural product isolation approaches rely on the use of pre-existing bioactivity information to inform the strategy used for the isolation of new bioactive compounds. Bioactivity information can be available either in the form of prior assay data or via Structure Activity Relationship (SAR) information which can indicate a potential chemotype that exhibits a desired bioactivity. The work described herein utilizes a unique method of targeted isolation using structure-based virtual screening to identify potential antibacterial compounds active against MRSA within the marine sponge order Verongiida. This is coupled with molecular networking-guided, targeted isolation to provide a novel drug discovery procedure. A total of 12 previously reported bromotyrosine-derived alkaloids were isolated from the marine sponge species Pseudoceratina durissima, and the compound, (+)-aeroplysinin-1 (1) displayed activity against the MRSA pathogen (MIC: <32 µg/mL). The compounds (1–3, 6 and 9) were assessed for their central nervous system (CNS) interaction and behavioral toxicity to zebrafish (Danio rerio) larvae, whereby several of the compounds were shown to induce significant hyperactivity. Anthelmintic activity against the parasitic nematode Haemonchus contorutus was also evaluated (2–4, 6–8). 相似文献
109.
110.
Wei Ouyang Jin-rong Ma Yong-qiang Wang Li-ting Qin Jie-yuan Jiang Hong-jie Fan Xiao-mei Wang Yong-shan Wang 《Veterinary microbiology》2013
Infectious bursal disease virus (IBDV) causes a highly contagious and immunosuppressive disease in young chickens and results in considerable economic losses for the poultry industry. To suppress the replication of IBDV, two short hairpin RNAs (shRNAs) were designed for targeting the VP1 and VP2 genes of IBDV. Recombinant plasmids carrying each shRNA or two shRNAs were constructed based on vector pSilencer2.1-U6 in which the human U6 promoter was replaced with chicken U6 promoter. In chicken embryo fibroblasts, transfection with these shRNA plasmids 24 h before infection with IBDV B87 reduced 50% tissue culture infectious doses (TCID50) from 108.75 TCID50/0.1 mL to 103.75–101.0 TCID50/0.1 mL. In 10-day old specific pathogen-free (SPF) chicken embryos, incubation with a mixture of IBDV B87 and a shRNA plasmid via the allantoic cavity resulted in 100% mortality and high IBDV virus titer in the control group but 25–0% mortality and near normal embryo development in the specific shRNA groups; additionally, IBDV VP1 and VP2 mRNA levels were reduced by 72–95% in the shRNA groups as compared with the control groups. When challenged with a virulent strain IBDV GX8/99, 14-day-old chickens pre-treated with the single shRNA plasmids or the dual shRNA plasmid showed approximately 70% or 90% survival at 5 days post-challenge while those pre-treated with control plasmid or saline had less than 5% survival. The current study suggests that two IBDV shRNAs expressed by a plasmid under chicken U6 promoter could effectively and synergistically reduce IBDV replication in vitro and in vivo. 相似文献