全文获取类型
收费全文 | 677篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
林业 | 54篇 |
农学 | 8篇 |
基础科学 | 5篇 |
123篇 | |
综合类 | 91篇 |
农作物 | 19篇 |
水产渔业 | 93篇 |
畜牧兽医 | 254篇 |
园艺 | 11篇 |
植物保护 | 64篇 |
出版年
2023年 | 3篇 |
2021年 | 21篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 9篇 |
2017年 | 15篇 |
2016年 | 18篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 31篇 |
2011年 | 44篇 |
2010年 | 26篇 |
2009年 | 21篇 |
2008年 | 49篇 |
2007年 | 51篇 |
2006年 | 38篇 |
2005年 | 50篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 39篇 |
2001年 | 14篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 11篇 |
1983年 | 3篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 9篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1971年 | 3篇 |
排序方式: 共有722条查询结果,搜索用时 15 毫秒
81.
Churchward CP Hlúšek M Nicholas RA Ayling RD McAuliffe L 《Veterinary microbiology》2012,159(1-2):257-259
Mycoplasma mycoides subspecies mycoides small colony is the aetiological agent of contagious bovine pleuropneumonia, a cattle disease endemic to areas of sub-Saharan Africa. Twenty isolates from various geographical locations and the type strain were analysed by multi-locus sequence analysis (MLSA). The data generated was then used to develop three PCR primer sets to differentiate these isolates. The PCRs differentiated the isolates into four groups; the type strain (T); isolates of European origin (Eu); isolates from Tanzania (Af1) with a final group consisting of isolates from Namibia and Botswana (Af2). These PCRs offers a rapid and efficient post-identification typing method without the need to sequence and analyse multiple genes. 相似文献
82.
François Courbet Jean-Christophe Hervé Etienne K. Klein Francis Colin 《Annals of Forest Science》2012,69(2):125-138
• Introduction
Branch size and branch status (dead or alive) are important characteristics closely related to tree growth and wood quality. The aim of this study was to design models for the diameter and status of branches in Atlas cedar (Cedrus atlantica Manetti). 相似文献83.
The use of native plants on green roofs has attracted considerable attention in recent years. With this comes the implicit assumptions that native plants are better adapted, provide greater environmental benefit, and are more aesthetically pleasing than non-native plants. We examined papers published in scholarly journals and papers presented at the annual North American green roof conference to identify who is promoting the use of native plants on green roofs, their rationale for doing so, and the scientific evidence to support the assertion that natives are better adapted. Architects, landscape architects, and biologists were the most likely to promote native plants and engineers were the least likely. Many of the reasons for using native plants on green roofs originate from ground-level landscaping and have simply been transplanted to the roof, without regard for the fact that the rooftop is a fundamentally different environment than the ground. Nearly half of all pro-native papers used the term “native” without definition. This review highlights the need for greater rigor and transparency when promoting the use of native plants and further demonstrates how misconceptions can result in sub-optimal green roof design and performance. 相似文献
84.
Flour milled from waxy durum grain was incorporated into bread formulations and its effects on crumb softness and loaf volume compared to those of added fats and emulsifiers. Waxy durum had a small effect on increasing loaf volume, and little of this effect could be explained by dough height or oven spring; effects of most other additives were closely related to dough height or oven spring. For all additives, the relationship between crumb softness and loaf volume fitted a power law relationship. Waxy durum and some of the additives had a greater softening effect than predicted from their effect on volume while others produced a much firmer crumb. With only one exception, when combined with other additives waxy durum reduced compression of the crumb more than predicted on the basis of the effects on loaf volume of the additives alone. In common with some of the added lipids, during compression analysis, crumb prepared with waxy durum flour had similar levels of structural damage as crumb baked from the standard formulation; other lipids and emulsifiers produced more fragile crumb. Waxy durum flour appears to have unique effects on crumb softness. 相似文献
85.
Katy Webb Colin Barker Tihana Harrison Zoe Heather Karen F. Steward Carl Robinson J. Richard Newton Andrew S. Waller 《Veterinary journal (London, England : 1997)》2013,195(3):300-304
Genome sequencing data for Streptococcus equi subspecies equi and zooepidemicus were used to develop a novel diagnostic triplex quantitative PCR (qPCR) assay targeting two genes specific to S. equi (eqbE and SEQ2190) and a unique 100 base pair control DNA sequence (SZIC) inserted into the SZO07770 pseudogene of S. zooepidemicus strain H70. This triplex strangles qPCR assay can provide results within 2 h of sample receipt, has an overall sensitivity of 93.9% and specificity of 96.6% relative to the eqbE singlex assay and detects S. equi at levels below the threshold of the culture assay, even in the presence of contaminating bacteria. 相似文献
86.
Extract This issue of the New Zealand Veterinary Journal contains our second Feature Review Series, this time comprising six state-of- the-art reviews on the Health and Welfare of Farmed Deer. Topics have been chosen to elaborate areas of veterinary science of both national and international importance, and have been contributed by acknowledged experts in these fields. This review series has been sponsored by the Deer Branch of the New Zealand Veterinary Association, whose support is gratefully acknowledged. Our intention is to include a Feature Review Series in the December issue of the Journal each year. Ed. 相似文献
87.
A range of commercially available cereals (mainly rye and wheat) used to manufacture U.K. bakery products were obtained, and the levels of free amino acids and sugars were measured. Selected samples were cooked as flours and doughs to generate acrylamide and the data compared with those obtained from a model system using dough samples that had been additionally fortified with asparagine (Asn) and sugars (glucose, fructose, maltose, and sucrose). In cooked flours and doughs, Asn was the key determinant of acrylamide generation. A significant finding for biscuit and rye flours was that levels of Asn were correlated with fructose and glucose. The results suggest that for these commercial cereals, selection based on low fructose and glucose contents, and hence low asparagine, could be beneficial in reducing acrylamide in products (e.g., crackers and crispbreads) that have no added sugars. 相似文献
88.
Migration pathways,speed and mortality of Atlantic salmon (Salmo salar) smolts in a Scottish river and the near‐shore coastal marine environment 下载免费PDF全文
Angus J. Lothian Matthew Newton James Barry Marcus Walters Richard C. Miller Colin E. Adams 《Ecology of Freshwater Fish》2018,27(2):549-558
Long‐distance migration of Atlantic salmon (Salmo salar) is known to result in high levels of mortality. For a species experiencing global population decline, it is thus vital to better understand migration behaviour, both in the river and marine stages. Atlantic salmon smolts (n = 50) were tracked using acoustic telemetry in the River Deveron, Scotland, and adjacent coastal area. Higher rates of mortality were observed in the river (0.77% per km) than the early marine stage of migration (0.0% per km). Mortality likely resulted from predation. Higher swim speeds were recorded in the early marine stage compared with the river (marine = 7.37 ± 28.20 km/day; river = 5.03 ± 1.73 km/day [mean ± SD]), a potential predator avoidance behaviour. The majority of smolts leaving the river did so in darkness and on a flooding tide. Overall river and marine migration success were linked to nights of lower lunar brightness. Marine migration speed decreased with increasing environmental noise levels, a finding with implications for fisheries management. The migration pathway in the early marine environment did not follow obvious geographical features, such as the coastline. Thus, we suggest that early marine environment pathways are more influenced by complex water currents. These findings highlight factors that influence smolt migration survival and behaviour, areas on which future research should focus. 相似文献
89.
90.
Thirlwall RE Commander NJ Brew SD Cutler SJ McGiven JA Stack JA 《Veterinary research communications》2008,32(3):209-213
This report describes the use of cell mediated immunity to improve specificity of current diagnosis for Brucella suis. Diagnosis is problematic due to cross reactions that lead to false positive serological reactions (FPSR) in the standard
diagnostic tests. A common cause of this cross reactivity is infection with the organism Yersinia enterocolitica O:9. Gottingen™ mini-pigs were experimentally infected with B. suis biovar I field strain or Y. enterocolitica serotype O:9 biotype 3. Infection was followed for 70 days. During this time whole blood stimulation assays were set up using
Brucella specific antigen. IFNγ was measured in the supernatants (SN) from these assays by ELISA. Concurrent standard serological
tests were carried out. The results indicate that the IFNγ assay is specifically able to distinguish Y. enterocolitica O:9 infection from a B. suis infection in experimentally infected mini-pigs. These results represent an improvement in diagnostic specificity compared
to currently used serological tests. Thus suggesting that in a surveillance setting this test could be applied as a confirmatory
test in the face of FPSR.
The authors are British Civil Servants and as such their work is subject to British Crown Copyright. This means the exclusive
copyright for the article cannot be transferred. 相似文献