全文获取类型
收费全文 | 366篇 |
免费 | 20篇 |
专业分类
林业 | 5篇 |
农学 | 9篇 |
基础科学 | 3篇 |
18篇 | |
综合类 | 59篇 |
农作物 | 10篇 |
水产渔业 | 5篇 |
畜牧兽医 | 263篇 |
园艺 | 4篇 |
植物保护 | 10篇 |
出版年
2023年 | 3篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 10篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 12篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 14篇 |
2006年 | 26篇 |
2005年 | 9篇 |
2004年 | 19篇 |
2003年 | 8篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 18篇 |
1999年 | 6篇 |
1997年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 2篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 5篇 |
1968年 | 3篇 |
1967年 | 5篇 |
1966年 | 2篇 |
排序方式: 共有386条查询结果,搜索用时 15 毫秒
51.
52.
Wilkins AL Rehmann N Torgersen T Rundberget T Keogh M Petersen D Hess P Rise F Miles CO 《Journal of agricultural and food chemistry》2006,54(15):5672-5678
Pectenotoxins from marine dinoflagellates of the genus Dinophysis are rapidly hydrolyzed by many shellfish to give pectenotoxin-2 seco acid, which isomerizes to 7-epi-pectenotoxin-2 seco acid. Three series of fatty acid esters of pectenotoxin-2 seco acid (PTX-2 seco acid) and 7-epi-PTX-2 seco acid were detected by LC-MS analysis of extracts from blue mussels (Mytilus edulis) from Ireland. The locations of the fatty acid ester linkages were identified by a combination of LC-MSn in positive- and negative-ion modes, LC-MS analysis of the products from reaction of the esters with sodium periodate, and NMR analysis of purified samples of the two most abundant ester derivatives. The 37-O-acyl esters of PTX-2 seco acid were the most abundant, followed by the corresponding 11-O-acyl esters, accompanied by low levels of the 33-O-acyl esters. The most abundant fatty acid esters in the fractionated sample were, in order, the 16:0, 22:6, 14:0, 16:1, 18:4, and 20:5 fatty acids, although a wide array of other PTX-2 seco acid fatty acid esters were also present at low levels. 相似文献
53.
T Jauffrais J Kilcoyne V Séchet C Herrenknecht P Truquet F Hervé JB Bérard C Nulty S Taylor U Tillmann CO Miles P Hess 《Marine drugs》2012,10(6):1360-1382
Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell · mL(-1) at steady state in bioreactors 1 and 2, respectively. The AZA cell quota decreased as the dilution rate increased from 0.15 to 0.3 day(-1), with optimum toxin production at 0.25 day(-1). After optimization, SPE procedures allowed for the recovery of 79 ± 9% of AZAs. The preparative isolation procedure previously developed for shellfish was optimized for algal extracts, such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of more than 70% was achieved, and isolation from 1200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 of >95% purity. This work demonstrated the feasibility of sustainably producing AZA1 and -2 from A. spinosum cultures. 相似文献
54.
B. N. Azuhnwi B. Boller M. Martens F. Dohme‐Meier S. Ampuero S. Günter M. Kreuzer H. D. Hess 《Grass and Forage Science》2011,66(4):474-487
Fifteen accessions of sainfoin (Onobrychis viciifolia Scop.) were characterized for morphological and phenological traits at Reckenholz in the Swiss lowlands (Experiment 1). The effects of accession, harvest time and site on dry‐matter yield, condensed tannin (CT) concentration and forage value (Experiment 2) were determined at three sites in Switzerland varying in altitude from 440 to 559 m. Three to four harvests were taken in the first year after establishment (second year of stand) with harvests 1 and 2 chemically analysed. From the characterization in Experiment 1, a clear grouping of single flowering (Communis) and multiple flowering (Bifera) accessions emerged. Additionally, within the Communis accessions, distinct groupings were identified (historical landraces and newly collected ecotypes) based on morphological characteristics. Experiment 2 showed that Communis and Bifera accessions had a similar chemical composition in the first harvest. In the second harvest, Communis accessions were higher in crude protein and CT and lower in neutral and acid detergent fibre concentrations than Bifera accessions. Total dry‐matter yields were higher for Bifera accessions. Among the Communis accessions, ecotypes had consistently higher CT concentrations than landraces. In vitro organic matter digestibility did not significantly differ among accessions. There were clear effects of harvest time and site for most variables, with clear harvest time × sainfoin group interaction but no site × sainfoin group interactions. The results clearly demonstrate that historical landraces and newly collected ecotypes expand the range of available genetic variation for sainfoin breeding. 相似文献
55.
Rachel C. Hector Marlis L. Rezende Khursheed R. Mama Eugene P. Steffey Heather K. Knych Ann M. Hess Juhana M. Honkavaara Marja R. Raekallio Outi M. Vainio 《Veterinary anaesthesia and analgesia》2017,44(4):755-765
Objective
To determine the effects of low and high dose infusions of dexmedetomidine and a peripheral α2-adrenoceptor antagonist, MK-467, on sevoflurane minimum alveolar concentration (MAC) in dogs.Study design
Crossover experimental study.Animals
Six healthy, adult Beagle dogs weighing 12.6 ± 0.9 kg (mean ± standard deviation).Methods
Dogs were anesthetized with sevoflurane in oxygen. After a 60-minute instrumentation and equilibration period, the MAC of sevoflurane was determined in triplicate using the tail clamp technique. PaCO2 and temperature were maintained at 40 ± 5 mmHg (5.3 ± 0.7 kPa) and 38 ± 0.5 ºC, respectively. After baseline MAC determination, dogs were administered two incremental loading and infusion doses of either dexmedetomidine (1.5 μg kg?1 then 1.5 μg kg?1 hour?1 and 4.5 μg kg?1 then 4.5 μg kg?1 hour?1) or MK-467 (90 μg kg?1 then 90 μg kg?1 hour?1 and 180 μg kg?1 then 180 μg kg?1 hour?1); loading doses were administered over 10 minutes. MAC was redetermined in duplicate starting 30 minutes after the start of drug administration at each dose. End-tidal sevoflurane concentrations were corrected for calibration and adjusted to sea level. A repeated-measures analysis was performed and comparisons between doses were conducted using Tukey's method. Statistical significance was considered at p < 0.05.Results
Sevoflurane MAC decreased significantly from 1.86 ± 0.3% to 1.04 ± 0.1% and 0.57 ± 0.1% with incremental doses of dexmedetomidine. Sevoflurane MAC significantly increased with high dose MK-467, from 1.93 ± 0.3% to 2.29 ± 0.5%.Conclusions and clinical relevance
Dexmedetomidine caused a dose-dependent decrease in sevoflurane MAC, whereas MK-467 caused an increase in MAC at the higher infusion dose. Further studies evaluating the combined effects of dexmedetomidine and MK-467 on MAC and cardiovascular function may elucidate potential benefits of the addition of a peripheral α2-adrenergic antagonist to inhalation anesthesia in dogs. 相似文献56.
Kilcoyne J Keogh A Clancy G LeBlanc P Burton I Quilliam MA Hess P Miles CO 《Journal of agricultural and food chemistry》2012,60(10):2447-2455
Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1-3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing ~14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile. 相似文献
57.
Silvia P. Turner Tanja Maria Hess Kibby Treiber Erica B. Mello Bruno G. Souza Fernando Q. Almeida 《Journal of Equine Veterinary Science》2011,31(11):645-649
Diets high in concentrates and soluble carbohydrates are associated with reduced insulin sensitivity in horses. Exercise training could protect against diet-induced insulin resistance. The objective of this study was to determine the intensity of exercise training required to affect insulin sensitivity in stabled horses fed a diet high in concentrates but moderate in soluble carbohydrates. In all, 31 stabled horses underwent three different exercise regimens: turnout, light exercise, and moderate exercise, while being fed a diet containing 60% concentrate. Blood was sampled monthly and analyzed for insulin. Insulin sensitivity was assessed using basal insulin concentrations and calculated insulin sensitivity (reciprocal of the square root of insulin) and compared across months by analysis of variance with repeated measures. Insulin sensitivity (reciprocal of the square root of insulin) was higher during periods of moderate and light physical activity as compared with turnout. These results indicate that turnout alone may not be adequate to improve insulin sensitivity in horses fed high amounts of concentrate. 相似文献
58.
Hess C Maegdefrau-Pollan B Bilic I Liebhart D Richter S Mitsch P Hess M 《Avian diseases》2011,55(4):714-718
The present report documents the occurrence of a poxvirus infection in commercial meat turkeys. The affected farm had six flocks, with a total of 11,680 birds at different ages; birds from two of these flocks were affected. The clinical picture was characterized by severe epithelial lesions and proliferations on the head and neck regions as reported for the cutaneous form of poxvirus infection. Except for these lesions, no adverse clinical signs or gross pathologic lesions were observed. Only a low number of birds was affected (n = 20) and no increase of mortality could be seen. Bacteriologic investigations from the lesions revealed multiresistant Staphylococcus aureus. Eosinophilic inclusions (Bollinger bodies) in histologic examinations in the cytoplasm of keratinocytes were noticeable. Typical pox virions were demonstrated by electron microscopy, and poxvirus was isolated on the chorioallantoic membrane of specific-pathogen-free chicken eggs. Further identification of the poxvirus species was carried out by PCR and sequencing, revealing an infection with the species fowlpox. Layers in vicinity of the turkey farm that also were affected by fowlpox were considered as potential source of infection. Although it is assumed that avian poxviruses are strongly species specific, the present case report reinforces the changing picture of poxvirus infections in turkeys. Furthermore, it supports the assumption of previous data that fowlpox virus has to be seen as recently emerging pathogen in turkeys. 相似文献
59.
Four commercial strains of chickens, namely, ISA brown leghorn (ISA), TETRA-SL brown (TETRA-SL), Lohmann brown (LB), and Lohmann LSL (LSL), were infected with a well-defined clonal culture of Histomonas meleagridis (H. meleagridis/Turkey/Austria/2922-C6/04) to investigate their susceptibility to histomonosis. Each group included 16 chickens, which were housed under the same conditions in separate pens. All chickens were infected with 10(4) histomonads orally and intracloacally at 14 days of age. No mortality or clinical signs were observed during the experiment in all birds. Three birds of each chicken strain were euthanatized on days 4, 7, 10, 14, and 21 postinfection. Incidence of histomonosis on the basis of cecal lesions was found to be 64.00% in TETRA-SL, 62.50% in LB, 53.12% in LSL, and 43.75% in ISA chickens. Fewer lesions were noticed in livers than in ceca, with an incidence of 15.62% in TETRA-SL, 9.37% in LB, and 3.12% in ISA chickens. No liver lesions were found in the LSL chickens. Statistical analysis revealed that there was no significant difference (P > 0.05) in susceptibility to experimental H. meleagridis infection based on cecal and liver involvement. Polymerase chain reaction (PCR) and immunohistochemistry were found to be reliable tools to confirm the presence of histomonads and changes in the ceca. However, some negative PCR results were recorded from the livers despite the presence of macroscopic lesions. Additionally, DNA of H. meleagridis was detected by PCR in a few of the lungs, but immunohistochemistry was negative. Nucleic acid of the protozoan parasite was not detected in samples from kidney, brain, spleen, or bursa of Fabricius. Altogether, the high susceptibility of commercial chicken lines to histomonosis could be demonstrated and characterized by severe lesions in the ceca and insignificant involvement of the liver, approaching a maximum on days 7-14 postinfection. 相似文献
60.
文章通过计算各种蛋氨酸源的影子价格并进行比较,探讨其在实际配方中的应用。以现有肉鸡日粮推荐为基础配制了288个试验日粮,DL-methionine为标准添加蛋氨酸,计算蛋氨酸类似物的影子价格。结果表明:液体蛋氨酸羟基类似物(MHA-FA)的影子价格受多种因素的影响,如果想要替代产品具有竞争力的话,应在假定生物学效价计算出的价格上减去大约5.6%。 相似文献