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   34篇
  免费   4篇
林业   3篇
  13篇
综合类   3篇
水产渔业   5篇
畜牧兽医   2篇
植物保护   12篇
  2022年   1篇
  2021年   2篇
  2018年   5篇
  2017年   3篇
  2016年   4篇
  2015年   1篇
  2014年   4篇
  2013年   1篇
  2012年   3篇
  2011年   4篇
  2010年   1篇
  2008年   2篇
  2007年   1篇
  2006年   2篇
  2005年   2篇
  2004年   1篇
  2002年   1篇
排序方式: 共有38条查询结果,搜索用时 15 毫秒
1.
This study verifies the instability of garlic ( Allium sativum L.)-derived allyl 2-propenylthiosulfinate (allicin) in various aqueous and ethanolic solutions as well as in vegetable oil through chemical and biological analyses performed simultaneously. Crushed fresh garlic cloves generated antibacterial activity and chemically detectable allicin, a major antibacterial principle, and both declined on a daily basis in aqueous and ethanolic solutions at room temperature, showing biological and chemical half-lives of about 6 and 11 days, respectively. Allicin was more stable in 20% alcohol than in water, but surprisingly unstable in vegetable oil, with an activity half-life 0.8 h, as estimated from its antibacterial activity toward Escherichia coli, and a chemical half-life of 3.1 h, based on chromatographic quantification. In alcoholic and aqueous extracts, the biological half-life of allicin tended to be longer than the chemical one, suggesting the occurrence of bioactive compounds other than allicin in the extracts.  相似文献   
2.
Vertisol soils of central India are heavy in texture, with high clay content and low organic matter. These soils are prone to degradation and the soil loss is due to poor management practices including excessive tillage. Based on a long-term study conducted for improving the quality of these soils, it was found that management practice such as low tillage (LT) + 4 t ha?1 compost + herbicide (Hb) recorded significantly higher organic carbon (OC) (6.22 g kg?1) and available N (188.5 kg ha?1) compared to conventional tillage (CT) + recommended fertilizer (RF) + off-season tillage (OT) + hand weeding (HW) (OC: 4.71 g kg?1, available nitrogen (N) (159.3 kg ha?1). Among the physical soil quality parameters, mean weight diameter (MWD) was significantly higher under LT + 4 t ha?1 straw + Hb (0.59 mm). The practice of LT + 4 t ha?1 straw + HW recorded significantly higher microbial biomass carbon (MBC) (388.8 μg g?1). The order of key indicators and their contribution towards soil quality was as follows: OC (29%) >, MBC (27%) > available zinc (Zn) (22%) > MWD (9%) > available boron (B) (8%), > dehydrogenase activity (DHA) (5%). The order of the best treatment which maintained soil quality index (SQI) values reasonably good (>1.5) was as follows: LT + 4t ha?1 compost + HW (1.65) > LT + 4 t ha?1 compost +Hb (1.60) > LT + 4t ha?1 straw + HW (1.50). Hence, these treatments could be recommended to the farmers for maintaining higher soil quality in Vertisols under soybean system. Correlation studies revealed stronger relationship between key indicators like OC (R2 = 0.627), MBC (R2 = 0.884), available Zn (R2 = 0.739) and DHA (R2 = 0.604) with Relative Soil Quality Index (RSQI). The results of the present study would be highly useful to the researchers, farmers and land managers.  相似文献   
3.
In this study, we infected NOD/Scid/Jak3null mice engrafted human peripheral blood leukocytes (hu-PBL-NOJ) with measles virus Edmonston B strain (MV-Edm) expressing hepatitis C virus (HCV) envelope proteins (rMV-E1E2) to evaluate the immunogenicity as a vaccine candidate. Although human leukocytes could be isolated from the spleen of mock-infected mice during the 2-weeks experiment, the proportion of engrafted human leukocytes in mice infected with MV (103–105 pfu) or rMV-E1E2 (104 pfu) was decreased. Viral infection of the splenocytes was confirmed by the development of cytopathic effects (CPEs) in co-cultures of splenocytes and B95a cells and verified using RT-PCR. Finally, human antibodies against MV were more frequently observed than E2-specific antibodies in serum from mice infected with a low dose of virus (MV, 100–101 pfu, and rMV-E1E2, 101–102 pfu). These results showed the possibility of hu-PBL-NOJ mice for the evaluation of the immunogenicity of viral proteins.  相似文献   
4.
(-) Hydroxycitric acid (HCA), an active ingredient extracted from the Garcinia cambogia fruit rind, has been commonly used as a dietary supplement for weight management. Given the controversy over HCA related testicular toxicity in animal studies, we investigated changes in serum sex hormones levels as an extension of our previous double-blind placebo-controlled trial in human subjects, in which 44 participants received either G. cambogia extract (1667.3 mg/day equivalent to 1000 mg HCA/day) or placebo for 12 weeks. Compared to the placebo group, administration of the extract did not significantly alter the serum testosterone, estrone, and estradiol levels. Similarly, hematology, serum triacylglycerol and serum clinical pathology parameters did not reveal any significant adverse effects. The results of this preliminary investigation indicate that ingestion of G. cambogia extract at dose levels commonly recommended for human use does not affect serum sex hormone levels and blood parameters.  相似文献   
5.
The components of the essential oils from seeds of Azadirachta indica, Azadirachta siamensis, and Azadi-rachta excelsa were studied by gas chromatography and gas chromatography-mass spectrometry. The main components of A. indica oil were hexadecanoic acid (34.0%), oleic acid (15.7%), 5,6-dihydro-2,4,6-triethyl-(4H)-1,3,5-dithiazine (11.7%), methyl oleate (3.8%), and eudesm-7(11)-en-4-ol (2.7%). The major components of A. siamensis oil were hexadecanoic acid (52.2%), tricosane (10.5%), tetradecanoic acid (6.8%), oleic acid (4.9%), and pentacosane (4.9%). Azadirachta excelsa oil contained oleic acid (31.3%), hexadecanoic acid (14.2%), octadecanoic acid (13.0%), 4-octylphenol (9.7%), and O-methyloximedecanal (6.8%) as the main constituents. The essential oils from A. indica, A. siamensis, and A. excelsa were found to contain fatty acids (52.6%–72.3%) as major components. The minor components of the oils were n-alkanes, aromatics, esters, sulfur and nitrogen compounds, and terpenoids. Differences in oil composition were observed between the three species.  相似文献   
6.
Although tropomyosin is known to be a major allergen of crustaceans, its structural information is limited to only five species. In this study, tropomyosin was confirmed to be a major allergen in six species of crustaceans (black tiger prawn, kuruma prawn, pink shrimp, king crab, snow crab, and horsehair crab) by immunoblotting. Then, the amino acid sequences of tropomyosins from these crustaceans were elucidated by a cDNA cloning technique. Sequence data for crustacean tropomyosins including the obtained results reveal that fast tropomyosins are contained in shrimps (or prawns) and lobsters, slow tropomyosins in crabs, and both tropomyosins in crayfishes and hermit crabs. Although fast and slow tropomyosins share a high sequence identity (about 90%) with each other, significant differences are observed in specific regions between both tropomyosins.  相似文献   
7.
Six mealybug species have been reported as citrus pests in the Mediterranean Basin: the citrus mealybugPlanococcus citri (Risso), the citriculus mealybugPseudococcus cryptus Hempel, the longtailed mealybugPseudococcus longispinus (Targioni-Tozzetti), the citrophilus mealybugPseudococcus calceolariae (Maskell), the obscure mealybugPseudococcus viburni (Signoret) and the spherical mealybugNipaecoccus viridis (Newstead). Some of these species,e.g. N. viridis, have recently been introduced into the region and are still spreading. Mealybugs are usually occasional or minor pests of citrus, but some species can reach key pest status. Mealybug management strategies in citrus have been based mostly on classical biological control and, to a lesser extent, on augmentative releases. However, chemical control is widely used, mainly because of the poor adaptation of the principal natural enemies to the climatic conditions of the Mediterranean. The application of pheromones is still restricted to monitoring the citrus mealybug, whose sex pheromone is commercially available. Mass trapping and mating disruption should be considered for possible use in IPM programs as an alternative method to supplementary chemical treatments. Enhancement of biological control through management of ant populations is another promising tactic for control of mealybugs. Strategies for managing mealybug pests of citrus, and possible levels of integration of different tactics according to the pest status, are discussed. http://www.phytoparasitica.org posting Oct. 3, 2004.  相似文献   
8.
A mature male rottweiler was evaluated for acute collapse and abdominal pain. The history consisted of concurrent administration of meloxicam and aspirin. On exploratory laparotomy, a large perforated ulcer was discovered in the proximal duodenum, with secondary peritonitis. The pathogenesis of NSAID-induced gastrointestinal ulceration and the supposed safety of COX-2 selective agents are discussed.  相似文献   
9.
The adduct of the hydroxyl radical with oxygen has been studied theoretically, in connection with atmospheric reactions, but its stability and structure remained an open question. Pure rotational spectra of the HOOO and DOOO radicals have now been observed in a supersonic jet by using a Fourier-transform microwave spectrometer with a pulsed discharge nozzle. The molecular constants extracted from 12 rotational transitions with fine and hyperfine splittings support a trans planar molecular structure, in contrast to the cis planar structure predicted by most ab initio calculations. The bond linking the HO and O2 moieties is fairly long (1.688 angstroms) and comparable to the F-O bond in the isoelectronic FOO radical.  相似文献   
10.
Midgut juice of Plutellaxylostella strain PXR which is resistant to Cry1Ac was biochemically characterized relative to the susceptible PXS strain. The midgut juice of PXR (PXR-Juice) was shown to process Cry1Ac protoxin to 60 kDa active toxin with the same processing pattern as that of juice from PXS (PXS-Juice) in SDS–PAGE. PXS larvae which were given the Cry1Ac toxin pre-processed with PXR-Juice were killed with the same rate as that with Cry1Ac pre-activated by trypsin. PXR-Juice was found to contain three times larger amount of 66 kDa protein (P66) than PXS-Juice and the N-terminal amino acid sequence of P66 was matched to that of glucosinolate sulfatase in data base search. The protein band of P66 was coincided with the band of p-nitro phenyl sulfatase activity in zymogram. P66 purified to homogeneity in SDS-PAGE bound to Cry1Ac and soybean agglutinin, and KD for Cry1Ac was estimated to be 718 nM with surface plasmon resonance analysis. Using purified sulfatase, Km and Vmax were estimated and involvement of the enzyme in the PXR resistance was discussed.  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