全文获取类型
收费全文 | 248篇 |
免费 | 18篇 |
专业分类
林业 | 20篇 |
农学 | 8篇 |
68篇 | |
综合类 | 12篇 |
农作物 | 16篇 |
水产渔业 | 54篇 |
畜牧兽医 | 61篇 |
园艺 | 4篇 |
植物保护 | 23篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有266条查询结果,搜索用时 687 毫秒
261.
262.
Ahlert J Shepard E Lomovskaya N Zazopoulos E Staffa A Bachmann BO Huang K Fonstein L Czisny A Whitwam RE Farnet CM Thorson JS 《Science (New York, N.Y.)》2002,297(5584):1173-1176
The enediynes exemplify nature's ingenuity. We have cloned and characterized the biosynthetic locus coding for perhaps the most notorious member of the nonchromoprotein enediyne family, calicheamicin. This gene cluster contains an unusual polyketide synthase (PKS) that is demonstrated to be essential for enediyne biosynthesis. Comparison of the calicheamicin locus with the locus encoding the chromoprotein enediyne C-1027 reveals that the enediyne PKS is highly conserved among these distinct enediyne families. Contrary to previous hypotheses, this suggests that the chromoprotein and nonchromoprotein enediynes are generated by similar biosynthetic pathways. 相似文献
263.
Bringa EM Caro A Wang Y Victoria M McNaney JM Remington BA Smith RF Torralva BR Van Swygenhoven H 《Science (New York, N.Y.)》2005,309(5742):1838-1841
Molecular dynamics simulations of nanocrystalline copper under shock loading show an unexpected ultrahigh strength behind the shock front, with values up to twice those at low pressure. Partial and perfect dislocations, twinning, and debris from dislocation interactions are found behind the shock front. Results are interpreted in terms of the pressure dependence of both deformation mechanisms active at these grain sizes, namely dislocation-based plasticity and grain boundary sliding. These simulations, together with new shock experiments on nanocrystalline nickel, raise the possibility of achieving ultrahard materials during and after shock loading. 相似文献
264.
Wang Y King JM Xu Z Losso J Prudente A 《Journal of agricultural and food chemistry》2008,56(17):7942-7949
The present study was conducted to determine the influence of an ozonation process on lutein and protein in clean and contaminated corns. This study aimed to determine the levels of lutein and protein in corn before and after ozonation and to verify the antimutagenic potential of the extracted lutein against aflatoxin using the Ames test. The lutein content was analyzed by high-performance liquid chromatography. Nitrogen analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to analyze protein. Clean ozone-treated corn had a total lutein content of 28.36 microg/g, which was higher than that of 22.75 microg/g in the untreated clean corn. However, the lutein content was 11.69 microg/g in the ozone-treated contaminated corn, which was lower than that of 16.42 microg/g in the untreated contaminated corn. In both corn samples, the protein content of ozone-treated corn was lower than that of untreated corn, indicating that protein could be destroyed by the ozonation process, which may influence the nutritious value of the corn. Lutein extracts alone showed no mutagenic potential against Salmonella typhimurium tester strains TA100. Lutein extracts from corn inhibited the mutagenicity of AFB1 in a dose-response manner more efficiently than lutein standard. Lutein extracts from different corn samples had similar antimutagenic potentials against AFB1, so the ozone treatment did not affect the antimutagenic potentials of lutein extracts. 相似文献
265.
Marcelo Nicolás Monte María Florencia Rey Burusco Martín Federico Carboni Martín Alfredo Castellote Sofía Sucar Natalia Sigrid Norero Silvana Lorena Colman Gabriela Alejandra Massa Mónica Liliana Colavita Sergio Enrique Feingold 《American Journal of Potato Research》2018,95(3):286-300
Andean Potato is a major crop for farmers in the Andes and represents an important gene pool for potato improvement. We present the population structure and genetic diversity of 88 Andigena accessions collected in Northwestern Argentina based on functional markers (25 SSR) distributed along 12 chromosomes. Polymorphic information content ranged from 0.40 to 0.87. A Bayesian approach, a Principal Coordinate Analysis and a Cluster Analysis revealed the presence of: I) a major group containing most of the Andean accessions and II) a smaller group including the out-group cv. Spunta and the sequenced genotype DM. Several group specific alleles were detected. AMOVA showed that 81% of the variability was within each group. Eleven of the SSRs analyzed are linked or within genes reported to regulate traits of nutritional and industrial interest. Additionally, the allelic variant of a photoperiod dependent tuberization regulator gene, StCDF1.2, was exclusively detected in accessions clustered in group II. 相似文献
266.
Amaury Ábrego-Gacía Héctor M.Poggi-Varaldo Vania Robles-González Teresa Ponce-Noyola Graciano Calva-Calva Elvira Ríos-Leal Daniel Estrada-Bárcenas Alfredo Mendoza-Vargas 《畜牧与生物技术杂志(英文版)》2022,(2):353-364
Methane from enteric fermentation is the gas with the greatest environmental impact emitted by ruminants.Lovastatin(Lv) addition to feedstocks could be a strategy to mitigate rumen methane emissions via decreasing the population of methanogenic archaea(MA). Thus, this paper provides the first overview of the effects of Lv supplementation, focusing on the inhibition of methane production, rumen microbiota, and ruminal fermentation.Results indicated that Lv treatment had a strong anti-methanogenic... 相似文献