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   104篇
  免费   4篇
林业   9篇
农学   2篇
  20篇
综合类   7篇
农作物   2篇
水产渔业   6篇
畜牧兽医   44篇
园艺   6篇
植物保护   12篇
  2021年   2篇
  2020年   5篇
  2019年   4篇
  2018年   3篇
  2017年   3篇
  2016年   3篇
  2015年   1篇
  2014年   6篇
  2013年   4篇
  2012年   8篇
  2011年   8篇
  2010年   6篇
  2009年   6篇
  2008年   6篇
  2007年   3篇
  2006年   8篇
  2005年   4篇
  2004年   10篇
  2003年   6篇
  2002年   7篇
  2001年   1篇
  1999年   3篇
  1980年   1篇
排序方式: 共有108条查询结果,搜索用时 31 毫秒
91.
Changes of plasma lysozyme and serum bactericidal activity, ceruloplasmin, total plasma protein, serum glucose, hematocrit and leucocrit levels in rainbow trout (Oncorhynchus mykiss) were studied after exposure to formalin and chloramine-T, which are used in aquaculture as anti-ectoparasitic and antibacterial agents. Fish were exposed to formalin at a concentration of 250 ppm for 60 min and exposed to chloramine-T for 5 ppm for 3 h. The parameters were analyzed for rainbow trout exposed to formalin and chloramine-T soon after treatments and rainbow trout exposed to freshwater after 24 h (return) following the treatments. Plasma lysozyme activity decreased after exposure to formalin; however, it was not affected by chloramine-T exposure. Serum bactericidal activity reduced after both formalin and chloramine-T exposure and did not change after returning to freshwater. Ceruloplasmin and total plasma protein were not affected by both treatments. Serum glucose levels of exposed fish elevated and remained at higher levels during recovery period when compared to control values. Hematocrit values of fish exposed to formalin increased; however, no significant change was observed in fish exposed to chloramine-T. Leucocrit levels of fish treated with both formalin and chloramine-T were higher than that of controls.  相似文献   
92.
Vegetable oils are promising candidates as substitutes for petroleum base oils in lubricant applications, such as total loss lubrication, military applications, and outdoor activities. Although vegetable oils have some advantages, they also have poor oxidation and low temperature stability. One of the ways to address these issues is chemical modification of fatty acid chain of triglyceride. We report a one-pot synthesis of a novel class of chemically modified vegetable oils from epoxidized triacylglycerols and various anhydrides. In an anhydrous solvent, boron trifluoride etherate is used as catalyst to simultaneously open the oxirane ring and activate the anhydride. The reaction was monitored and products confirmed by NMR, FTIR, GPC, and TGA analysis. Experimental conditions were optimized for research quantity and laboratory scale-up (up to 4 lbs). The resultant acyl derivatives of vegetable oil, having diester substitution at the sites of unsaturation, have potential in formulation of industrial fluids such as hydraulic fluids, lubricants, and metal working fluids.  相似文献   
93.
This study was conducted to assess the role of increasing N supply in enrichment of whole grain and grain fractions, particularly the endosperm, with Zn and Fe in wheat. The endosperm is the most widely consumed part of wheat grain in many countries. Plants were grown in the greenhouse with different soil applications of N and Zn and with or without foliar Zn spray. Whole grain and grain fractions were analyzed for N, P, Zn and Fe. Increased N supply significantly enhanced the Zn and Fe concentrations in all grain fractions. In the case of high Zn supply, increasing N application enhanced the whole grain Zn concentration by up to 50% and the endosperm Zn by over 80%. Depending on foliar Zn supply, high N elevated the endosperm Fe concentration up to 100%. High N also generally decreased the P/Zn and P/Fe molar ratios in whole grain and endosperm. The results demonstrate that improved N nutrition, especially when combined with foliar Zn treatment, is effective in increasing Zn and Fe of the whole grain and particularly the endosperm fraction, at least in the greenhouse, and might be a promising strategy for tackling micronutrient deficiencies in countries where white flour is extensively consumed.  相似文献   
94.
The effects of plant growth promoting bacteria (PGPB) on the fruit yield, growth and nutrient element content of strawberry cv. Fern were investigated under organic growing conditions between 2006 and 2008. The experimental plot was a completely randomized design with 3 replicates. Three PGPB strains (Pseudomonas BA-8, Bacillus OSU-142 and Bacillus M-3) were used alone or in combination as bio-fertilizer agent in the experiment. Data through 3 years showed that the use of PGPB significantly increased fruit yield, plant growth and leaf P and Zn contents. Root inoculation of M3 and floral and foliar spraying of OSU-142 and BA-8 bacteria stimulated plant growth resulting in significant yield increases. M3 + BA-8, BA-8 + OSU-142, M3, M3 + OSU-142 and BA-8 applications increased cumulative yield by 33.2%, 18.4%, 18.2%, 15.3% and 10.5%, respectively. Number of fruits per plant significantly increased by the applications of M3 + BA-8 (91.73) and M3 (81.58) compared with the control (68.66). In addition, P and Zn contents of strawberry leaves with bacterial inoculation significantly increased under organic growing conditions. Available P contents in soil were increased from 0.35 kg P2O5/da at the beginning of the study to 2.00, 1.97 and 1.82 kg P2O5/da by M3 + OSU-142, M3 + BA-8 and M3 + BA-8 + OSU-142 applications, respectively. Overall, the results of this study suggest that root inoculation of Bacillus M3 alone or in combination with spraying Bacillus OSU-142 or Pseudomonas BA-8 have the potential to increase the yield, growth and nutrition content of strawberry plant under organic growing conditions.  相似文献   
95.
Cortisol and finfish welfare   总被引:1,自引:0,他引:1  
Previous reviews of stress, and the stress hormone cortisol, in fish have focussed on physiology, due to interest in impacts on aquaculture production. Here, we discuss cortisol in relation to fish welfare. Cortisol is a readily measured component of the primary (neuroendocrine) stress response and is relevant to fish welfare as it affects physiological and brain functions and modifies behaviour. However, we argue that cortisol has little value if welfare is viewed purely from a functional (or behavioural) perspective—the cortisol response itself is a natural, adaptive response and is not predictive of coping as downstream impacts on function and behaviour are dose-, time- and context-dependent and not predictable. Nevertheless, we argue that welfare should be considered in terms of mental health and feelings, and that stress in relation to welfare should be viewed as psychological, rather than physiological. We contend that cortisol can be used (with caution) as a tractable indicator of how fish perceive (and feel about) their environment, psychological stress and feelings in fish. Cortisol responses are directly triggered by the brain and fish studies do indicate cortisol responses to psychological stressors, i.e., those with no direct physicochemical action. We discuss the practicalities of using cortisol to ask the fish themselves how they feel about husbandry practices and the culture environment. Single time point measurements of cortisol are of little value in assessing the stress level of fish as studies need to account for diurnal and seasonal variations, and environmental and genetic factors. Areas in need of greater clarity for the use of cortisol as an indicator of fish feelings are the separation of (physiological) stress from (psychological) distress, the separation of chronic stress from acclimation, and the interactions between feelings, cortisol, mood and behaviour.  相似文献   
96.
Arterial vascularisation of the ovine pineal gland was investigated by latex injection preparations of the common carotid artery in 20 adult Akkaraman sheep brains under stereo light microscope. It was observed that the arterial supply comes exclusively from branches of the caudal cerebral artery. The pineal gland was found to contain a rich vascular network. This network also received a few branches from the caudal choroid rami.  相似文献   
97.
Pseudomonas viridiflava is one of the causal agents of tomato stem necrosis in the eastern Mediterranean region of Turkey. The bacterium causes general wilting, yellowing of tomato plants, dark blotches on the pruning sites of the stem, browning, and hollowing of the pith.P. viridiflava strains, isolated from Antakya and Mersin, were identified by traditional methods and indirect enzyme-linked immunosorbent assay (ELISA). For indirect-ELISA, polyclonal antisera were produced against a regional isolate ofP. viridiflava (AD-OZ 3a). Using indirect-ELISA, the pathogenic bacterium was identified rapidly and safely from both pure culture and inoculated plants in 2 days. There was no cross reaction with other stem necrosis pathogens. With indirect-ELISA, the lower limit forP. viridiflava detection in pure culture was 103 colony-forming units per milliliter. http://www.phytoparasitica.org posting Feb. 11, 2004.  相似文献   
98.
This study reports an anatomical study of the vascular supply in 20 Akkaraman sheep cerebelli from adult subjects of both sexes. The origin and branching pattern of the cerebellar artery vascularising the cerebellar nuclei were studied by gross dissection and vascular injection. Then dissection was performed and vessels nourishing the cerebellar nuclei were documented. Four bilaterally symmetrical cerebellar nuclei were determined as nucleus lateralis cerebelli, nucleus interpositus lateralis cerebelli, and nucleus interpositus medialis cerebelli and nucleus fastigii from lateral to medial side. It has been previously confirmed that vascularisation of the cerebellar nuclei is carried out by intermediary branches of the rostral cerebellar artery and the caudal cerebellar artery. However, this study has confirmed that the caudal cerebellar artery has no contribution in the vascularisation of the cerebellar nuclei.  相似文献   
99.
The purpose of this study was to evaluate the sedative-anaesthetic effects of a combination of medetomidine (M, 50 microg per pigeon), butorphanol (B, 50 microg per pigeon) and ketamine (K, 25 mg per pigeon) in domestic pigeons. Eight domestic pigeons (four male and four female, 8-15 months old) were used. The combination of Medetomidine and butorphanol injectable solutions were used to produce sedation. Ten minutes after M + B administration, K was injected. The anaesthetic effects of the drugs were reversed by administration of Atipamazole (AT) at 60 min after K administration. All drugs were injected into the pectoral muscles. The sedative-anaesthetic effects of the M + B-K combination and, alterations in respiratory rate (RR), heart rate (HR), electrocardiographic (ECG) findings and cloacal temperature (CT) were investigated before and 10 min after pre-medication with M + B, at 5, 15, 30, 45 and 60 min during the onset of K anaesthesia and at 1, 5, 10, 20, 30 and 60 min following the administration of AT. The HR and RR of pigeons decreased within 10 min following M + B administration and remained lower until 1st and 5 min of AT injection, respectively. In ECG, no significant alterations in P, Q, R and S-values were observed, however, arhythmia was recorded for three pigeons, which returned to normal values following AT administration throughout the measurement. Cloacal temperature decreased gradually during the anaesthesia from 41.0 to 32.7 degrees C. The drug combination used in this study produced a satisfactory general anaesthesia for seven of the eight pigeons. All pigeons were unconscious within 5 min after K administration as indicated by disappearance of the palpebral and corneal reflexes and lack of reaction to the pain stimuli during the study. The effect of AT administration was observed within 10 min as all pigeons responded partly against stimuli and all reflexes. It is concluded that M + B-K anaesthesia in pigeons is a safe and reliable anaesthetic protocol for surgery.  相似文献   
100.
The aim of this study was to determine the level and duration of progesterone secretion during the sequential oestrous cycles in fat-tailed Tuj ewes following tactile and visual separation of rams during the breeding season. For these purposes, rams were separated from the main flock for 50 days starting from the beginning of the breeding season and 21 ewes were randomly selected for the current experiment. In order to assess luteal activity and the length of oestrous cycles, the ewes were blood-sampled thrice or twice weekly for the measurement of progesterone in plasma. The data showed that 3 +/- 0.2 oestrous cycles were observed in this time window, and the first oestrous cycle observed was shorter (P < 0.05) than the following cycles (mean +/- SEM, 14.6 +/- 0.82, 16.5 +/- 0.48 and 17.0 +/- 0.54 days, respectively, for cycles 1, 2 and 3). Progesterone production was significantly lower in the first oestrous cycle compared with the second and third cycles on days 9, 12 and 14 of the cycles. The follicular periods of ewes showed four accumulations (maximum values using a 3-day moving average technique) throughout the study and the percentages of ewes at each accumulation (peak day +/- 1 day) were 50, 35, 65 and 80% for the first, second, third and fourth accumulations, respectively (P < 0.05). It was concluded that progesterone production was lower and the oestrous cycles were shorter during the first oestrous cycle and that tactile and visual separation of rams at the beginning of the breeding season might enhance the synchronizing effect towards the end of the breeding season in the fat-tailed Tuj ewes.  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