首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   114篇
  免费   0篇
林业   16篇
  42篇
综合类   1篇
农作物   3篇
水产渔业   2篇
畜牧兽医   49篇
园艺   1篇
  2022年   1篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2014年   1篇
  2013年   2篇
  2012年   9篇
  2011年   7篇
  2010年   2篇
  2009年   6篇
  2008年   13篇
  2007年   7篇
  2006年   7篇
  2005年   12篇
  2004年   7篇
  2003年   5篇
  2002年   1篇
  2001年   6篇
  2000年   2篇
  1999年   6篇
  1998年   1篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1989年   2篇
  1988年   4篇
  1987年   2篇
  1985年   1篇
  1975年   1篇
  1957年   1篇
排序方式: 共有114条查询结果,搜索用时 15 毫秒
1.
The effects of health classification and of housing and management on performance and meat inspection findings were studied in 166 all-in-all-out finishing herds in Finland in 1995 and 1998. Producers could buy either health-classified (certified free of certain diseases) or standard-class pigs for their farms. Herds that had attained a certain level of housing and management were eligible to join the LSO 2000 management system for finishing herds. In 1995, none of the study herds were LSO 2000 units. In 1998, 76 of them had become LSO 2000 units, while 90 had remained as non-LSO 2000 units. Continuous outcome variables (daily gain and time in the finishing unit) were analysed with a mixed-model procedure with repeated measurements from the same farms. Discrete variables were analysed either with Poisson regression (mortality, whole- and partial-carcass condemnations, organ condemnations, arthritis, abscesses) or logistic regression (liver condemnations, pneumonia, pleuritis). The models were adjusted for the year, size of the herd and the average slaughter weight of the batch.The benefits obtained by the health classification of the feeder pigs included a substantial increase in daily gain (37g, about 5%) and decrease in time in the finishing unit (4 days, about 4%), decrease in mortality (odds ratio, OR 0.68), a substantial decrease in pneumonia (OR 0.37) and pleuritis (OR 0.60), and a substantial decrease in liver (OR 0.45) and organ (OR 0.72) condemnations. Classification of the pigs did not have an effect on the prevalence of whole-carcass condemnations, arthritis or abscesses. The health-classified pigs had, unexpectedly, more partial-carcass condemnations (OR 1.15) than the standard-class pigs. The obtained benefits of the LSO 2000 units were an increase in daily gain (14g, about 2%), decrease in time in the finishing unit (2 days, about 2%), a decrease in mortality (OR 0.69) and a decrease in whole-carcass (OR 0.69) and partial-carcass (OR 0.81) condemnations. The LSO 2000 units did not have any advantage over the non-LSO 2000 units in their prevalence of liver or organ condemnations, arthritis, abscesses, pneumonia or pleuritis.  相似文献   
2.
This study was conducted to determine whether the seasonal delay in puberty in autumn is driven by individual differences in night-time melatonin secretion in domestic gilts at the attainment of puberty. A group of spring-born gilts (n = 30) were expected to reach puberty in autumn by the age of 7 months. Eighteen of these gilts were selected in pairs on the basis of matched days of birth. By the expected time, half of the animals showed oestrous symptoms (group CYCLING, n = 9) with the rest remaining silent (group SILENT, n = 9). Afterwards, all gilts were fitted with indwelling jugular catheters for frequent blood sampling. Blood samples were collected from all animals three times during the day followed by three times in the night at 2-h intervals for 48 h. The samples were analysed by a commercial radioimmunoassay (RIA). The results show a consistent 25-fold rise (on average) in night-time melatonin concentration in every animal sampled with group averages ranging from 0.28 +/- 0.04 to 0.37 +/- 0.06 pg/ml at day and from 10.20 +/- 2.16 to 10.67 +/- 0.05 pg/ml at night. Night-time group mean values between CYCLING and SILENT gilts did not differ significantly (10.26 +/- 0.67 and 10.38 +/- 0.94 for the CYCLING; 10.67 +/- 0.05 and 10.20 +/- 2.16 for the SILENT). When 10 pg/ml was used as a threshold value, six individuals did not reach it during the night (low responders). Two of these gilts were CYCLING and four were SILENT. In conclusion, the results presented imply no involvement of the level of night-time melatonin concentration in the seasonal delay of puberty in gilts.  相似文献   
3.
The effect of vulvar discharge syndrome (VDS) on sow and gilt fertility was studied on 26 farms. Of 824 animals inspected in 21 randomly selected and five VDS problem farms, 19 (2.3%) were afflicted with VDS. Altogether 542/799 of the examined animals (67.8%) farrowed thereafter. Nine of the 19 VDS animals (47.4%) and 533/780 non-VDS animals (68.3%) farrowed at the first chance after the examination (p = 0.05). None of the unmated gilts in this study had VDS. Environmental and individual factors likely to be associated with fertility and VDS were tested. In multivariate analysis, factors associated with farrowing were VDS, reproductive status, availability of roughage and confinement to individual stalls. None of the variables tested was associated with VDS. However, all of the VDS problem farms were overcrowded and had concrete, partly slatted floors with little or no bedding. The median value of haptoglobin (Hp) was 2.5 (range 1.3-3.1) g/l in VDS animals and 2.3 (0.5-4.3) g/l in controls (p = 0.6). The median C-reactive protein (CRP) in VDS animals was 30.3 (3.3-171.3) mg/l and in controls 25.9 (3.3-361.1) mg/l (p = 0.7). In conclusion, VDS decreased fertility of gilts and sows in the absence of a systemic acute-phase response, as indicated by stable concentrations of Hp and CRP.  相似文献   
4.
Fruiting of Heterobasidion on cull pieces and stumps of Norway spruce was investigated in cutting areas and mature spruce stands located in southern Finland. Cull pieces of variable size and showing butt rot were left on three clear‐cut areas and in one thinned stand. Additionally, a part of the cull pieces was transported to mature forest sites with closed canopy. During the succeeding 3–4 years the cull pieces were investigated annually for sporocarps of Heterobasidion, and the area of actively sporulating pore layer of each sporocarp was measured. Root bases of spruce stumps in the logging areas were excavated and sporocarps found on the stumps also measured. At the onset of the experiment, Heterobasidion spp. were isolated from 76% of the cull pieces showing butt rot; 85% of the isolates were identified as H. parviporum and 15% as H. annosum s.s. During the following 3–4 years sporocarps were found on 20% of the 1938 cull pieces where Heterobasidion butt rot was initially detected visually. Sporocarp formation was promoted by advancement of butt rot, increasing cull piece diameter and end‐to‐end ground contact, but restricted by the colonization of the cull piece by Stereum sanguinolentum. Between‐site differences were significant but could not be explained by differences in tree cover. At the end of the investigation period the average sporulating area of Heterobasidion sporocarp per metre of cull piece was higher than the average sporulating area per stump at three of four logging sites. Hence, leaving cull pieces containing Heterobasidion butt rot at logging areas in southern Finland can considerably increase local production of Heterobasidion spores.  相似文献   
5.
Oxidation of bovine serum albumin, casein, and lactalbumin and the effect of different procyanidins, anthocyanins, and their aglycons (10 and 20 microM) on lactalbumin oxidation were investigated in a liposome system. Samples were incubated in the dark at 37 degrees C with copper, and the extent of oxidation was measured by determining the loss of tryptophan fluorescence and the formation of protein carbonyls, conjugated diene hydroperoxides, and hexanal. The correlation between different protein and lipid oxidation measurements was good and statistically significant. Casein was the most stable protein in the liposome model, and it was also the best inhibitor of liposome oxidation. All tested anthocyanins and other phenolic compounds inhibited both lipid and protein oxidation. There were no systematic differences with anthocyanins and their aglycons in relation to the concentrations used or glycosylation with either glucose or rutinose. Procyanidins B1 and B2 and ellagic acid were potentially better antioxidants than anthocyanins due to their several hydroxyl groups as measured by both protein and lipid oxidation. In conclusion, oxidative deterioration of liposomes due to protein-lipid interaction is inhibited by anthocyanins, procyanidins, and ellagitannin present, for example, in berries.  相似文献   
6.
For northern Europe’s climate, models predict an increase in periods of drought and waterlogging. Knowledge of variation between genotypes of Betula pendula (birch) and Populus tremula (aspen) to drought and excess soil moisture are unavailable but relevant for future development of forest ecosystems. We studied variation between genotypes to soil moisture in birch and aspen with plant material representing naturally regenerated populations and showed differences in acclimation to soil moisture conditions. Genotypes showing most growth and biomass accumulation across treatments maintained most leaf area, high gas exchange and water-use efficiency and grew most root mass but had the lowest root length per unit root dry mass compared to other genotypes. This indicates that these genotypes are more efficient in harvesting water from the soil under adverse conditions. We also showed that birch and aspen employ different strategies to cope with soil moisture conditions, with aspen investing more in perennial parts, while birch efficiently maintains foliar processes. When the expression of some known drought responsive genes was measured, only ACC oxidase was induced by the drought treatment at the beginning of the experiment, while surprisingly LEA5, RD22 and ADH1 did not respond to drought, but were up-regulated in prolonged wet conditions indicating oxidative stress and hypoxia and that these genes are responding to multiple stress factors. We conclude that in plants micro-propagated from naturally regenerated birch and aspen populations, there is variation between genotypes in acclimation efficiency to soil moisture conditions.  相似文献   
7.
The aim of this study was to characterize antioxidant activities of phenolic compounds that appear in olive pulp and olive oils using both radical scavenging and antioxidant activity tests. Antiradical and antioxidant activities of olive pulp and olive oil phenolic compounds were due mainly to the presence of a 3,4-dihydroxy moiety linked to an aromatic ring, and the effect depended on the polarity of the phenolic compound. Glucosides and more complex phenolics exhibited higher antioxidant activities toward oxidation of liposomes, whereas in bulk lipids aglycons were more potent antioxidants with the exception of oleuropein. Lignans acted as antioxidants only in liposomes, which could partly be due to their chelating activity, because liposome oxidation was initiated by cupric acetate. The antioxidant activity of virgin olive oil is principally due to the dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), a secoiridoid derivative (peak RT 36, structure unidentified), and luteolin.  相似文献   
8.
9.
The efficacy of ketoprofen in the treatment of non-infectious lameness in sows was examined in a double-blinded study. Two dose rates of oral ketoprofen were compared to placebo treatment over five consecutive days. Lameness was assessed with a five-grade scoring system prior to and on the last day of the treatment. The rate of treatment success was 54.3% for the ketoprofen 4mg/kg group (n=46), 53.2% for the ketoprofen 2mg/kg group (n=47) and 20.8% for the pigs in the placebo group (n=48). The difference between both ketoprofen groups and the placebo group was significant (P=0.001), but there was no difference between the two ketoprofen groups (P=0.78). Oral ketoprofen was well tolerated and no adverse events were observed. As lameness is a very common problem in sows, oral ketoprofen appeared to be a practical way to alleviate pain and improve the welfare of sows.  相似文献   
10.
Antioxidant activity of anthocyanins and their aglycons   总被引:13,自引:0,他引:13  
The antioxidant activity of the six common anthocyanidins, pelargonidin, cyanidin, delphinidin, peonidin, petunidin, and malvidin, and their glycosidic forms was evaluated in three lipid-containing models [human low-density lipoprotein (LDL) and bulk and emulsified methyl linoleate]. In addition, the radical scavenging activity of the compounds against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical was studied. Most anthocyanins and their aglycons acted as strong antioxidants in emulsion and LDL. Many compounds showed an activity comparable to the well-known antioxidants alpha-tocopherol, Trolox, catechin, and quercetin. In bulk methyl linoleate, anthocyanins and anthocyanidins possessed only a weak antioxidant activity or even oxidation-promoting activity. Depending on the anthocyanidin, different glycosylation patterns either enhanced or diminished the antioxidant power. For the most part, the activities of the glycosides and the aglycons did not differ remarkably in emulsion. In LDL the aglycons showed in general higher activities than the glycosides. In bulk oil, to the contrary, the glycosides were more effective than the aglycons.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号