全文获取类型
收费全文 | 641篇 |
免费 | 52篇 |
专业分类
林业 | 47篇 |
农学 | 7篇 |
基础科学 | 2篇 |
80篇 | |
综合类 | 61篇 |
农作物 | 20篇 |
水产渔业 | 33篇 |
畜牧兽医 | 383篇 |
园艺 | 4篇 |
植物保护 | 56篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 11篇 |
2021年 | 27篇 |
2020年 | 15篇 |
2019年 | 22篇 |
2018年 | 15篇 |
2017年 | 20篇 |
2016年 | 23篇 |
2015年 | 18篇 |
2014年 | 32篇 |
2013年 | 24篇 |
2012年 | 63篇 |
2011年 | 54篇 |
2010年 | 28篇 |
2009年 | 36篇 |
2008年 | 44篇 |
2007年 | 51篇 |
2006年 | 47篇 |
2005年 | 36篇 |
2004年 | 28篇 |
2003年 | 16篇 |
2002年 | 25篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有693条查询结果,搜索用时 11 毫秒
1.
Rebecca J. Kessler Shelley Rankin Sheri Young Kathleen O'Shea Maria Calabrese Amy Guldin Nicole Lipson Donna A. Oakley Urs Giger 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2010,39(1):29-38
Background: While screening programs have reduced the risk of infectious disease transmission by donors in human and veterinary blood banking, bacterial contamination of blood products has emerged as a major complication in human medicine. Objectives: To describe a Pseudomonas fluorescens (Pf)‐contaminated feline packed RBC (pRBC) unit and experimentally investigate Pf‐contaminated canine pRBCs. Methods: Canine pRBCs were inoculated with Pf‐rich pRBCs from the sentinel feline unit and stored at 4°C or 20°C for 72 hours. Aliquots from the pRBCs were serially evaluated by microscopy, culture, and a eubacterial 16S rRNA real‐time PCR assay. Results: One Pf‐contaminated feline unit turned black after 22 days of storage and was removed from the blood bank; a source was not found, and no other contaminated units were identified. Canine pRBCs spiked with 5 or 25 μL of the sentinel unit became culture‐ and/or 16S PCR‐positive at ≥8 hours at 20°C and 48 hours at 4°C and developed a color change at ≥24 hours. Sensitivity studies indicated that without incubation, inoculation of ≥100 μL Pf‐rich pRBCs was necessary for a positive 16S PCR test result. Conclusions: P. fluorescens grows in stored pRBCs slowly at 4°C and rapidly at 20°C. Screening of blood products for color change, estimating bacterial concentration with microscopy, and 16S PCR testing are simple and fast ways to detect bacteria in stored blood. Aseptic collection, temperature‐controlled storage, and regular visual monitoring of stored units is recommended. Discolored units should not be transfused, but examined for bacterial contamination or other blood product quality problems. 相似文献
2.
Landscape Ecology - Pollinator declines and functional homogenization of farmland insect communities have been reported. Mass-flowering crops (MFC) can support pollinators by providing floral... 相似文献
3.
Viral haemorrhagic septicaemia virus (VHSV) is a rhabdovirus that infects over 48 species of teleosts and is lethal in many. VHSV threatens marine and aquatic fisheries. VHSV was first discovered outside Europe in 1988 in fish from the Pacific coast of North America. In 1994, VHSV was discovered in Newfoundland. In 2003, VHSV was isolated from fish in Lake St. Clair (Michigan and Ontario). In this study, we used 46 nucleotide sequences for the glycoprotein gene from 12 studies and 150 nucleotide sequences for the nucleoprotein gene from nine studies. We combined phylogenetics and a geographic information system to visualize the transmission paths of VHSV lineages. We also reconstructed the spread of VHSV lineages through optimization of geographic data for viral isolates on phylogenetic trees. We demonstrate that VHSV was transmitted from the North Atlantic Ocean and/or Baltic Sea to the Atlantic coast of North America and Japan in independent events. From the Atlantic coast, the virus was transmitted independently to the Laurentian Great Lakes and the Pacific coast of Canada and the contiguous United States. From the Pacific Northwest, the virus was transmitted to Asia and Alaska in independent events. These results clarify the debate ongoing in the literature on the geographic spread of VHSV. 相似文献
4.
García-González DL Barie N Rapp M Aparicio R 《Journal of agricultural and food chemistry》2004,52(25):7475-7479
A novel electronic nose based on solid-phase microextraction (SPME) coupled with a surface acoustic wave (SAW) sensor array has been used to analyze different quality virgin olive oils. A mathematical model was designed with 37 samples to distinguish lampante from the other virgin olive oils categories (extra-virgin and virgin), because lampante-virgin olive oils cannot be consumed without a previous refining process. The model, successfully validated with a test set of 16 samples, was able to classify 90% of the samples correctly. Misclassifications were explained by SPME-HRGC analyses and a second sensory evaluation. 相似文献
5.
Sabine Augustin Jan Evers Hans-Peter Dietrich Johannes Eichhorn Thomas Haussmann Regina Icke Ansgar Isenberg Wolfgang Lux Monica Musio Hans Pretzsch Winfried Riek Thomas Rötzer Bernd Schultze Andreas Schulze Jörg Schröder Walter Seidling Nicole Wellbrock Klaus von Wilpert Barbara Wolff 《European Journal of Forest Research》2005,124(4):251-260
In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and
other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system
in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse
effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary
air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring
was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and
feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal
Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives
of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification
and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading
to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected
level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis
(crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative,
as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the
extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.
相似文献
Sabine AugustinEmail: |
6.
Coliform mastitis (CM) is not only a serious economical and animal welfare touching problem in dairy cattle, but also in sows after farrowing. Due to this disease, the essential adequate supply with colostrum for the growth and the health of the piglets is not ensured. Besides other influencing factors, Escherichia (E.) coli is of great importance as a causative agent of this multifactorial disease. In this study, E. coli isolates from milk samples of healthy and CM-affected sows were examined for the presence of virulence genes associated with extraintestinal E. coli strains, enterotoxigenic E. coli and other pathogenic E. coli. The isolated E. coli harbored mainly virulence genes of extraintestinal E. coli strains (especially fimC, ompA, traT, hra, kpsMTII, iroN). The virulence gene spectrum for both samples from CM-affected and healthy sows did not differ significantly. Particular virulence gene profiles of E. coli isolates from diseased sows were not detected. This study provides novel insights into the role of E. coli in association with mastitis in sows since it is the first time E. coli isolates from CM-affected sows' milk were analysed for virulence genes. Because there were no differences in the prevalence of E. coli and their virulence-associated genes between healthy and diseased sows, other causative factors seem to have greater influence on the pathogenesis of porcine CM. 相似文献
7.
Zimmerman AD Buterbaugh RE Herbert JM Hass JM Frank NE Luempert Iii LG Chase CC 《Journal of the American Veterinary Medical Association》2007,231(9):1386-1389
OBJECTIVE: To evaluate the efficacy of an inactivated bovine herpesvirus-1 (BHV-1) vaccine to protect against BHV-1 challenge-induced abortion and stillbirth. DESIGN: Prospective study. ANIMALS: 35 beef heifers. PROCEDURES: Before breeding, heifers were vaccinated with a commercially available BHV-1 inactivated vaccine SC or IM. The estrous cycle was then synchronized, and heifers were artificially inseminated 30 to 60 days after vaccination. Heifers (n = 21) were challenge inoculated IV at approximately 180 days of gestation with virulent BHV-1. Fourteen control heifers were not vaccinated. Clinical signs of BHV-1 infection were monitored for 10 days following challenge; serologic status and occurrence of abortion or stillbirth were evaluated until time of calving. RESULTS: 18 of 21 (85.7%) heifers that received vaccine were protected from abortion following challenge, whereas all 14 control heifers aborted. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that an inactivated BHV-1 vaccine can protect against abortion resulting from a substantial challenge infection, with efficacy similar to that of modified-live BHV-1 vaccines. 相似文献
8.
9.
10.
Clinicopathological Phenotype of Autosomal Recessive Cholesterol Deficiency in Holstein Cattle 下载免费PDF全文