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   124篇
  免费   7篇
林业   6篇
农学   3篇
  16篇
综合类   5篇
水产渔业   2篇
畜牧兽医   93篇
园艺   1篇
植物保护   5篇
  2022年   1篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2018年   8篇
  2017年   5篇
  2016年   4篇
  2015年   2篇
  2014年   5篇
  2013年   7篇
  2012年   10篇
  2011年   13篇
  2010年   4篇
  2009年   7篇
  2008年   8篇
  2007年   4篇
  2006年   6篇
  2005年   5篇
  2004年   5篇
  2003年   6篇
  2002年   7篇
  2001年   4篇
  2000年   2篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1992年   3篇
  1991年   1篇
  1990年   1篇
  1987年   2篇
  1971年   1篇
排序方式: 共有131条查询结果,搜索用时 36 毫秒
1.
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   
2.
Nitric oxide (NO) and nitrous oxide (N2O) emissions were measured from experimental dung and urine patches placed on boreal pasture soil during two growing seasons and one autumn period until soil freezing. N2O emissions in situ were studied by a static chamber method. NO was measured with a dynamic chamber method using a NO analyser in situ. Mean emissions from the control plots were 47.6±4.5 μg N2ON m−2 h−1 and 12.6±1.6 μg NON m−2 h−1. N2O and NO emissions from urine plots (132±21.2 μg N2ON m−2 h−1 and 51.9±7.6 μg NON m−2 h−1) were higher than those from dung plots (110.0±20.1 μg N2ON m−2 h−1 and 14.7±2.1 μg NON m−2 h−1). There was a large temporal variation in N2O and NO emissions. Maximum N2O emissions were measured a few weeks after dung or urine application, whereas the maximum NO emissions were detected the following year. NO was responsible on average 14% (autumn) and 34% (summer) of total (NO+N2O)N emissions from the pasture soil. NO emissions increased with increasing soil temperature and with decreasing soil moisture. N2O emissions increased with increasing soil moisture, but did not correlate with soil temperature. Therefore we propose that N2O and NO were produced mainly during different microbial processes, i.e., nitrification and denitrification, respectively. The results show that the overall conditions and mechanism especially for emissions of NO are still poorly understood but that there are differences in the mechanisms regulating N2O and NO production.  相似文献   
3.
4.
Various types of chromosomal aberrations, including numerical (aneuploidy) and structural (e.g., translocations, deletions), are commonly found in human tumors and are linked to tumorigenesis. Aneuploidy is a direct consequence of chromosome segregation errors in mitosis, whereas structural aberrations are caused by improperly repaired DNA breaks. Here, we demonstrate that chromosome segregation errors can also result in structural chromosome aberrations. Chromosomes that missegregate are frequently damaged during cytokinesis, triggering a DNA double-strand break response in the respective daughter cells involving ATM, Chk2, and p53. We show that these double-strand breaks can lead to unbalanced translocations in the daughter cells. Our data show that segregation errors can cause translocations and provide insights into the role of whole-chromosome instability in tumorigenesis.  相似文献   
5.
ObjectiveTo compare the haemodynamic effects of three premedicant regimens during propofol-induced isoflurane anaesthesia.Study designProspective, randomized cross-over study.AnimalsEight healthy purpose-bred beagles aged 4 years and weighing mean 13.6 ± SD 1.9 kg.MethodsThe dogs were instrumented whilst under isoflurane anaesthesia prior to each experiment, then allowed to recover for 60 minutes. Each dog was treated with three different premedications given intravenously (IV): medetomidine 10 μg kg?1 (MED), medetomidine 10 μg kg?1 with MK-467 250 μg kg?1 (MMK), or acepromazine 0.01 mg kg?1 with butorphanol 0.3 mg kg?1 (AB). Anaesthesia was induced 20 minutes later with propofol and maintained with isoflurane in oxygen for 60 minutes. Heart rate (HR), cardiac output, arterial blood pressures (ABP), central venous pressure (CVP), respiratory rate, inspired oxygen fraction, rectal temperature (RT) and bispectral index (BIS) were measured and arterial and venous blood gases analyzed. Cardiac index (CI), systemic vascular resistance index (SVRI), oxygen delivery index (DO2I), systemic oxygen consumption index (VO2I) and oxygen extraction (EO2) were calculated. Times to extubation, righting, sternal recumbency and walking were recorded. The differences between treatment groups were evaluated with repeated measures analysis of covariance.ResultsHR, CI, DO2I and BIS were significantly lower with MED than with MMK. ABP, CVP, SVRI, EO2, RT and arterial lactate were significantly higher with MED than with MMK and AB. HR and ABP were significantly higher with MMK than with AB. However, CVP, CI, SVRI, DO2I, VO2I, EO2, T, BIS and blood lactate did not differ significantly between MMK and AB. The times to extubation, righting, sternal recumbency and walking were significantly shorter with MMK than with MED and AB.Conclusions and clinical relevanceMK-467 attenuates certain cardiovascular effects of medetomidine in dogs anaesthetized with isoflurane. The cardiovascular effects of MMK are very similar to those of AB.  相似文献   
6.

Background

Overwintering (breeding) reindeer (Rangifer tarandus tarandus) are commonly treated with ivermectin against parasitic infestations once yearly in autumn-winter roundups. The only preparations registered to reindeer are those for subcutaneous injection. However, also oral extra-label ivermectin administration is used. Twenty-six, 8-month-old reindeer calves were randomly allocated into three groups. Group 1 (n = 9) received oral ivermectin mixture (Ivomec® vet mixt. 0.8 mg/ml, oral ovine liquid drench formulation), Group 2 (n = 9) oral ivermectin paste (Ivomec® vet 18.7 mg/g equine paste), and Group 3 (n = 8) subcutaneous injection of ivermectin (Ivomec® 10 mg/ml vet inj.), each group at a dose of 200 μg/kg body weight. Blood samples were collected at treatment and at days 1, 2, 3, 6, 9 and 16 post treatment. Plasma concentrations of ivermectin were determined by high-pressure liquid chromatography (HPLC) with fluorescence detection.

Results

The peak plasma concentration (Cmax) was reached by 2 days after each treatment. The Cmax and Area Under Curve (AUC) differed significantly between the groups: Cmax was 30.2 ± 3.9, 14.9 ± 5.7 and 63.1 ± 13.1 ng/ml, and AUC was 2881 ± 462, 1299 ± 342 and 6718 ± 1620 ng*h/ml for groups 1, 2 and 3, respectively (mean ± standard deviation).

Conclusions

The differences in plasma concentrations of ivermectin are concomitant with earlier observed differences in antiparasitic efficacy, which discounts the use of the equine paste in reindeer in favour of the oral ovine liquid drench formulation, or preferably, the reindeer-registered subcutaneous injection formulation.  相似文献   
7.

Background

Recurrent colic and unexplained weight loss despite good appetite and adequate feeding and management practices are common conditions in the horse. However, little information has been published on the systematic diagnostic evaluation, response to treatment, prognostic factors or outcome of either presentation. The aims of this study were to 1) identify possible prognostic indicators and 2) report the short- and long-term response to treatment with corticosteroid therapy of a variety of horses with a presumptive diagnosis of inflammatory bowel disease (IBD).Thirty-six horses with a history of recurrent colic and/or unexplained weight loss were screened with a detailed clinical, clinicopathological and diagnostic imaging examination. Twenty horses were subsequently selected that had findings consistent with inflammatory bowel disease based on the fulfilment of one or more of the following additional inclusion criteria: hypoproteinaemia, hypoalbuminaemia, malabsorption, an increased intestinal wall thickness on ultrasonographic examination or histopathological changes in rectal biopsy. These 20 horses were treated with a standardized larvicidal anthelmintic regime and a minimum of three weeks of corticosteroid therapy.

Results

The initial response to treatment was good in 75% (15/20) of horses, with a 3-year survival rate of 65% (13/20). The overall 3-year survival in horses that responded to initial treatment (12/15) was significantly higher (P = 0.031) than in those that did not respond to initial treatment (1/5). The peak xylose concentration was significantly (P = 0.048) higher in survivors (1.36 ± 0.44 mmol/L) than non-survivors (0.94 ± 0.36 mmol/L).

Conclusions

The overall prognosis for long-term survival in horses with a presumptive diagnosis of IBD appears to be fair to moderate, and the initial response to anthelmintic and corticosteroid therapy could be a useful prognostic indicator. The findings of the present study suggest that a low peak xylose concentration in absorption testing is associated with a less favourable prognosis, supporting the use of this test.  相似文献   
8.
Abstract

Winter turnip rape (Brassica rapa spp. oleifera) is an underutilized crop that deserves to be revitalized for use in high-latitude agriculture. Many crop rotations around the world are dependent on the small-grain cereals, and turnip rape as a break crop, with its range of secondary chemicals, helps to suppress weeds, nematodes and pathogenic fungi. It may be used as an energy crop, it can restrict erosion and nutrient leaching while also improving soil structure and fertility, and it requires relatively low inputs. Although winter turnip rape was once the major oil crop in Finland, in the 1970s it was replaced by spring turnip rape, the lower erucic acid and glucosinolate contents of which made it suitable for food and feed uses. Winter hardiness of the crop could be improved, and industrial end uses, such as lubricants for which high erucic acid content is preferred, targeted in the first instance. Breeding progress would be accelerated by a change from the predominantly self-incompatible breeding system to self-compatibility, now available in modern germplasm, and this would allow use of other rapid breeding methods, such as doubled haploidy. Thus, the many advantages of the winter turnip rape crop would repay its return to agriculture. In this review we will introduce the many utilization possibilities of the crop as well as give background on why more attention and research efforts should be paid towards this crop. We will also indicate some of the array of factors that have a marked role in an attempt to ecologically intensify crop production.  相似文献   
9.
The reversal of the cardiovascular effects of the α2-adrenoceptor agonist detomidine by the α2-antagonist atipamezole was studied. Nine horses were given detomidine 20 μg/kg iv. On a separate occasion they were given atipamezole 100 μg/kg iv 15 mins after the detomidine injection. Blood gas tensions were measured and clinical signs of sedation were also observed. Bradycardia and the frequency of heart blocks induced by detomidine were reduced after atipamezole and blood pressure decreased. These reversal effects of atipamezole were of short duration (a few minutes) at the dose level tested. Two of the nine horses exhibited premature depolarisations after administration of detomidine, but not after atipamezole injection. PaO2 decreased and PaCO2 increased slightly after detomidine injection, but the arterial pH was within reference values or slightly elevated. Administration of atipamezole did not alter these values. Base excess rose after detomidine, and it decreased more quickly towards the baseline level, when the horses were given detomidine alone. No clinical adverse effects were seen from the administration of atipamezole. Atipamezole may be beneficial, if detomidine-induced bradycardia needs to be reversed in horses.  相似文献   
10.
The influence of dietary protein, methionine, and lysine on leather quality in blue fox pelts was studied. The pelt material originated from animals in two consecutive feeding trials (Exp. 1 and Exp. 2) with three protein levels: conventional, slightly lowered, and very low. The two lowest protein diets were fed as such or as supplemented with methionine or with lysine (lysine only in Exp. 2). The following physical leather properties were measured: breaking load (BRL), tensile strength (TEN), relative elongation at break (PEB), straining of skins at pelting, and shrinkage at dressing. A decline in the dietary protein content reduced BRL and, hence, leather firmness, and increased straining and the corresponding shrinking in Exp. 1. The supplemented methionine tended to improve leather strength and elasticity by increasing TEN and PEB in Exp. 1, whereas lysine elicited no response. Methionine supplementation at the slightly lowered protein level increased BRL in both experiments by almost 10% as compared with the respective non-supplemented diet. We conclude that with high protein quality diets, a level of 200 g/kg DM (as digestible protein) appears to be adequate for producing pelts with firm, elastic leather, provided that an adequate amount of methionine is included in the diet.  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