全文获取类型
收费全文 | 849篇 |
免费 | 66篇 |
专业分类
林业 | 10篇 |
农学 | 23篇 |
基础科学 | 1篇 |
71篇 | |
综合类 | 145篇 |
农作物 | 19篇 |
水产渔业 | 33篇 |
畜牧兽医 | 551篇 |
园艺 | 20篇 |
植物保护 | 42篇 |
出版年
2023年 | 8篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 18篇 |
2017年 | 21篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 17篇 |
2013年 | 51篇 |
2012年 | 28篇 |
2011年 | 48篇 |
2010年 | 27篇 |
2009年 | 16篇 |
2008年 | 29篇 |
2007年 | 28篇 |
2006年 | 28篇 |
2005年 | 21篇 |
2004年 | 33篇 |
2003年 | 29篇 |
2002年 | 26篇 |
2001年 | 28篇 |
2000年 | 30篇 |
1999年 | 25篇 |
1998年 | 9篇 |
1997年 | 13篇 |
1996年 | 17篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 27篇 |
1991年 | 12篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 18篇 |
1987年 | 12篇 |
1986年 | 21篇 |
1985年 | 22篇 |
1984年 | 15篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1971年 | 7篇 |
1970年 | 6篇 |
1967年 | 4篇 |
排序方式: 共有915条查询结果,搜索用时 125 毫秒
71.
Sutton T Baumann U Hayes J Collins NC Shi BJ Schnurbusch T Hay A Mayo G Pallotta M Tester M Langridge P 《Science (New York, N.Y.)》2007,318(5855):1446-1449
72.
Films of silicon dioxide (SiO2) were deposited at room temperature by means of catalyzed binary reaction sequence chemistry. The binary reaction SiCl4 + 2H2O --> SiO2 + 4HCl was separated into SiCl4 and H2O half-reactions, and the half-reactions were then performed in an ABAB ellipsis sequence and catalyzed with pyridine. The pyridine catalyst lowered the deposition temperature from >600 to 300 kelvin and reduced the reactant flux required for complete reactions from approximately 10(9) to approximately 10(4) Langmuirs. Growth rates of approximately 2.1 angstroms per AB reaction cycle were obtained at room temperature for reactant pressures of 15 millitorr and 60-second exposure times with 200 millitorr of pyridine. This catalytic technique may be general and should facilitate the chemical vapor deposition of other oxide and nitride materials. 相似文献
73.
Ranson H Claudianos C Ortelli F Abgrall C Hemingway J Sharakhova MV Unger MF Collins FH Feyereisen R 《Science (New York, N.Y.)》2002,298(5591):179-181
The emergence of insecticide resistance in the mosquito poses a serious threat to the efficacy of many malaria control programs. We have searched the Anopheles gambiae genome for members of the three major enzyme families- the carboxylesterases, glutathione transferases, and cytochrome P450s-that are primarily responsible for metabolic resistance to insecticides. A comparative genomic analysis with Drosophila melanogaster reveals that a considerable expansion of these supergene families has occurred in the mosquito. Low gene orthology and little chromosomal synteny paradoxically contrast the easily identified orthologous groups of genes presumably seeded by common ancestors. In A. gambiae, the independent expansion of paralogous genes is mainly a consequence of the formation of clusters among locally duplicated genes. These expansions may reflect the functional diversification of supergene families consistent with major differences in the life history and ecology of these organisms. These data provide a basis for identifying the resistance-associated enzymes within these families. This will enable the resistance status of mosquitoes, flies, and possibly other holometabolous insects to be monitored. The analyses also provide the means for identifying previously unknown molecules involved in fundamental biological processes such as development. 相似文献
74.
75.
76.
77.
78.
Soft-bodied and lightly sclerotized Burgess shale fossils have been found at more than a dozen new localities in an area extending for 20 kilometers along the front of the Cathedral Escarpment in the Middle Cambrian Stephen Formation of the Canadian Rockies. Five different fossil assemblages from four stratigraphic levels have been recognized. These assemblages represent distinct penecontemporaneous marine communities that together make up a normal fore-reef faunal complex. 相似文献
79.
A neutralizing antibody selected from plasma cells that binds to group 1 and group 2 influenza A hemagglutinins 总被引:2,自引:0,他引:2
Corti D Voss J Gamblin SJ Codoni G Macagno A Jarrossay D Vachieri SG Pinna D Minola A Vanzetta F Silacci C Fernandez-Rodriguez BM Agatic G Bianchi S Giacchetto-Sasselli I Calder L Sallusto F Collins P Haire LF Temperton N Langedijk JP Skehel JJ Lanzavecchia A 《Science (New York, N.Y.)》2011,333(6044):850-856
The isolation of broadly neutralizing antibodies against influenza A viruses has been a long-sought goal for therapeutic approaches and vaccine design. Using a single-cell culture method for screening large numbers of human plasma cells, we isolated a neutralizing monoclonal antibody that recognized the hemagglutinin (HA) glycoprotein of all 16 subtypes and neutralized both group 1 and group 2 influenza A viruses. Passive transfer of this antibody conferred protection to mice and ferrets. Complexes with HAs from the group 1 H1 and the group 2 H3 subtypes analyzed by x-ray crystallography showed that the antibody bound to a conserved epitope in the F subdomain. This antibody may be used for passive protection and to inform vaccine design because of its broad specificity and neutralization potency. 相似文献
80.