全文获取类型
收费全文 | 3063篇 |
免费 | 139篇 |
国内免费 | 356篇 |
专业分类
林业 | 211篇 |
农学 | 172篇 |
基础科学 | 159篇 |
382篇 | |
综合类 | 1398篇 |
农作物 | 231篇 |
水产渔业 | 129篇 |
畜牧兽医 | 608篇 |
园艺 | 141篇 |
植物保护 | 127篇 |
出版年
2024年 | 20篇 |
2023年 | 74篇 |
2022年 | 148篇 |
2021年 | 120篇 |
2020年 | 104篇 |
2019年 | 123篇 |
2018年 | 100篇 |
2017年 | 154篇 |
2016年 | 99篇 |
2015年 | 130篇 |
2014年 | 163篇 |
2013年 | 190篇 |
2012年 | 264篇 |
2011年 | 228篇 |
2010年 | 242篇 |
2009年 | 210篇 |
2008年 | 240篇 |
2007年 | 196篇 |
2006年 | 176篇 |
2005年 | 136篇 |
2004年 | 75篇 |
2003年 | 63篇 |
2002年 | 67篇 |
2001年 | 71篇 |
2000年 | 46篇 |
1999年 | 34篇 |
1998年 | 23篇 |
1997年 | 13篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1956年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有3558条查询结果,搜索用时 15 毫秒
11.
12.
猪ASC及Ub基因的克隆及真核表达重组质粒的构建 总被引:1,自引:0,他引:1
炎症小体不仅参与机体的天然免疫反应,同时还参与机体抗病毒等多种宿主防御反应。在多种疾病相关信号通路反应中都伴随着蛋白质的泛素化修饰。NOD样受体(NLRs)介导的炎症小体信号通路中,凋亡相关点状样蛋白(ASC)是关键的接头蛋白。为了解猪瘟病毒(CSFV)感染对ASC泛素化水平的影响,通过RT-PCR从猪血管内皮细胞(ECs)中扩增获得ASC和泛素(Ub)的全长cDNA双链片段,连接至克隆载体pMD-18T,获得重组克隆质粒pMD-ASC和pMD-Ub。双酶切pMD-ASC获得ASC目的序列,连接至pcDNA3.1-Flag,双酶切pMD-Ub获得Ub目的序列,连接至pcDNA3.0-HA,获得重组表达质粒pcDNA3.1-Flag-ASC和pcDNA3.0-HA-Ub。将pcDNA3.1-Flag-ASC和pcDNA3.0-HA-Ub转染ECs,Western blot在蛋白水平检测ASC和Ub的表达。结果表明,成功构建了带有Flag标签的ASC真核表达质粒和带有HA标签的Ub真核表达质粒,且在ECs中获得高效表达,为进一步体外研究CSFV调控猪血管内皮细胞ASC泛素化的机制提供了实验基础。 相似文献
13.
14.
A herd of 15 Chinese elephants attracted international attention during their 2021 northward trek, motivating the government to propose establishment of an Asian elephant national park. However, planning is hampered by a lack of genetic information on the remaining populations in China. We collected DNA from 497 dung samples from all 5 populations encompassing the entire range of elephants in China and used mitochondrial and microsatellite markers to investigate their genetic and demographic structure. We identified 237 unique genotypes (153 females, 84 males), representing 81% of the known population. However, the effective population size was small (28, range 25–32). Historic demographic contraction appeared to account for low haplotype diversity (Hd = 0.235), but moderate nucleotide and nuclear diversity (π = 0.6%, He = 0.55) was attributable to post-bottleneck recovery involving recent population expansion plus historical gene exchange with elephants in Myanmar, Lao PDR, and Vietnam. The 5 populations fell into 3 clusters, with Nangunhe elephants differing consistently from the other 4 populations (FST = 0.23); elephants from Mengyang, Simao, and Jiangcheng belonged to a single population (henceforth, MSJ), and differed from the Shangyong population (FST = 0.11). Interpopulation genetic variation reflected isolation by distance and female-biased dispersal. Chinese elephants should be managed as 2 distinct units: Nangunhe and another combining Shangyong and MSJ; their long-term viability will require restoring gene flow between Shangyong and MSJ, and between elephants in China and neighboring countries. Our results have the potential to inform conservation planning for an iconic megafaunal species. 相似文献
15.
This experiment was intend to study the changes of long non-coding RNA (H19) expression levels in skeletal muscle development and regeneration,and lay the foundation of its mechanism reach in skeletal muscle development.C2C12 cell line and ICR mice were used as experimental material,bioinformatics assay was used to exploit its non-coding character and low conservatism in different species,and the expressions of H19 in C2C12 cell differentiation,skeletal muscle development and the phase of muscle regeneration were detected by quantitative Real-time PCR (qRT-PCR).The results showed that,H19 expression levels in postnatal mouse skeletal muscle decreased with increasing age;during C2C12 cell differentiation,H19 mRNA increased gradually,and then maintained a high level;The expression of H19 was maintained at a high level through days 4 to 6 after injury.In consideration of its express character in C2C12 cell differentiation and skeletal muscle damage repair model,H19 may play an important role in promoting myogenesis and skeletal muscle regeneration. 相似文献
16.
17.
为了建立了维他昔布咀嚼片体外溶出度的测定方法,以0.8%十二烷基硫酸钠溶液为溶出介质,采用桨法(50 r/min),用紫外-可见分光光度法测定溶出度.结果显示,维他昔布浓度在0.002496 ~0.017472 mg/mL范围内,与吸收度呈良好的线性关系(r=0.9995),加样回收率为102.9%(RSD为1.36%),三批样品30 min时溶出度在80%以上.建立的溶出度测定方法重现性,均一性良好,样品溶出度大于80%,可用于维他昔布咀嚼片中溶出度的测定. 相似文献
18.
19.
20.