全文获取类型
收费全文 | 172篇 |
免费 | 6篇 |
专业分类
林业 | 29篇 |
农学 | 2篇 |
50篇 | |
综合类 | 16篇 |
农作物 | 5篇 |
水产渔业 | 10篇 |
畜牧兽医 | 59篇 |
园艺 | 2篇 |
植物保护 | 5篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 10篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 12篇 |
2009年 | 8篇 |
2008年 | 10篇 |
2007年 | 15篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1996年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1977年 | 3篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1965年 | 3篇 |
1930年 | 2篇 |
1927年 | 10篇 |
排序方式: 共有178条查询结果,搜索用时 359 毫秒
1.
Hanyeh Sepahvand Reza Mirzaeitalarposhti Torsten Müller 《Archives of Agronomy and Soil Science》2013,59(13):1820-1830
ABSTRACTThe aim of this study was to examine the usefulness of physical and chemical fractionation in quantifying soil organic matter (SOM) in different stabilized fraction pools. Soil samples from three land use types in Lorestan province, Southwest Iran were examined to account for the amount of organic carbon and nitrogen in different SOM fractions. Size/density separation and chemical oxidation methods were applied to separate the SOM fractions including particulate organic matter (POM), Si + C (silt and clay), DOC (dissolved organic C), rSOM (oxidation-resistant organic carbon and nitrogen) and S + SA (sand and stable aggregates). The values obtained for TOC, TN, and HWC were highest in forest lands followed by the range and agricultural lands. Among the SOM fractions, S + SA showed the highest values (5.75, 5.77 and 20.6 g kg?1 for agriculture, range and forest lands respectively) followed by POM, Si + C, rSOM, and DOC. The concentrations of C and N in the labile fractions obtained the higher values than in the stabilized fractions. Forest lands had the highest amounts of organic C and N among all fractions whereas agricultural lands showed highest values for inorganic C content of soils in different fractions. 相似文献
2.
Sjolund M. Jennifer Arnsdorf Yvonne M. Carnegie Mairi Fornefeld Eva Will Torsten 《植物病害和植物保护杂志》2019,126(1):89-92
Journal of Plant Diseases and Protection - Psyllids are small, phloem-feeding insects. Several species are vectors of economically important pathogens, such as ‘Candidatus Liberibacter... 相似文献
3.
Observed flow compensation associated with the MOC at 26.5 degrees N in the Atlantic 总被引:3,自引:0,他引:3
Kanzow T Cunningham SA Rayner D Hirschi JJ Johns WE Baringer MO Bryden HL Beal LM Meinen CS Marotzke J 《Science (New York, N.Y.)》2007,317(5840):938-941
The Atlantic meridional overturning circulation (MOC), which provides one-quarter of the global meridional heat transport, is composed of a number of separate flow components. How changes in the strength of each of those components may affect that of the others has been unclear because of a lack of adequate data. We continuously observed the MOC at 26.5 degrees N for 1 year using end-point measurements of density, bottom pressure, and ocean currents; cable measurements across the Straits of Florida; and wind stress. The different transport components largely compensate for each other, thus confirming the validity of our monitoring approach. The MOC varied over the period of observation by +/-5.7 x 10(6) cubic meters per second, with density-inferred and wind-driven transports contributing equally to it. We find evidence for depth-independent compensation for the wind-driven surface flow. 相似文献
4.
5.
E. Rohmeder W. Laatsch Mägdefrau Huber A. Bernhart K. Rubner Schwenke und H. Wiedemann 《Forstwissenschaftliches Centralblatt》1965,84(5-6):194-200
Ohne Zusammenfassung 相似文献
6.
Torsten Larsson 《Biological conservation》1977,11(2):129-143
This paper briefly reviews some of the problems of nature conservation in Sweden and the legislative and other measures which have been recently taken in this field. The organisation and responsibility of different conservation bodies are described. An intensive debate about activities such as localisation of industries inimical to the environment, modern forestry and off-road driving has resulted in new guidelines or legislative measures in recent years. Site protection by means of the Nature Conservancy Act is believed to be the most effective way of safeguarding areas valuable to scientific conservation and outdoor recreation. Some examples of fauna preservation and habitat management are mentioned. 相似文献
7.
Eilhard Wiedemann 《Forstwissenschaftliches Centralblatt》1927,49(22):815-827
Ohne Zusammenfassung 相似文献
8.
Eilhard Wiedemann 《Forstwissenschaftliches Centralblatt》1927,49(15):545-554
Ohne Zusammenfassung 相似文献
9.
European Journal of Forest Research - 相似文献
10.
Ragnhild J Bager Egle Kudirkiene Isabelle da Piedade Torsten Seemann Tine K Nielsen Susanne E Pors Andreas H Mattsson John D Boyce Ben Adler Anders M Bojesen 《Veterinary research》2014,45(1)
The Gram-negative bacterium Gallibacterium anatis is a major cause of salpingitis and peritonitis in commercial egg-layers, leading to reduced egg production and increased mortality. Unfortunately, widespread multidrug resistance and antigenic diversity makes it difficult to control infections and novel prevention strategies are urgently needed. In this study, a pan-genomic reverse vaccinology (RV) approach was used to identify potential vaccine candidates. Firstly, the genomes of 10 selected Gallibacterium strains were analyzed and proteins selected on the following criteria; predicted surface-exposure or secretion, none or one transmembrane helix (TMH), and presence in six or more of the 10 genomes. In total, 42 proteins were selected. The genes encoding 27 of these proteins were successfully cloned in Escherichia coli and the proteins expressed and purified. To reduce the number of vaccine candidates for in vivo testing, each of the purified recombinant proteins was screened by ELISA for their ability to elicit a significant serological response with serum from chickens that had been infected with G. anatis. Additionally, an in silico prediction of the protective potential was carried out based on a protein property prediction method. Of the 27 proteins, two novel putative immunogens were identified; Gab_1309 and Gab_2312. Moreover, three previously characterized virulence factors; GtxA, FlfA and Gab_2156, were identified. Thus, by combining the pan-genomic RV approach with subsequent in vitro and in silico screening, we have narrowed down the pan-proteome of G. anatis to five vaccine candidates. Importantly, preliminary immunization trials indicated an in vivo protective potential of GtxA-N, FlfA and Gab_1309.