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   79篇
  免费   3篇
林业   13篇
农学   2篇
基础科学   2篇
  11篇
综合类   5篇
农作物   11篇
水产渔业   6篇
畜牧兽医   28篇
园艺   1篇
植物保护   3篇
  2022年   2篇
  2021年   1篇
  2020年   5篇
  2019年   4篇
  2018年   5篇
  2017年   7篇
  2016年   5篇
  2015年   2篇
  2014年   3篇
  2013年   5篇
  2012年   11篇
  2011年   6篇
  2010年   6篇
  2009年   3篇
  2008年   2篇
  2007年   4篇
  2006年   3篇
  2005年   6篇
  2003年   1篇
  2002年   1篇
排序方式: 共有82条查询结果,搜索用时 15 毫秒
51.
High inclusion levels of dehulled lupin (Lupinus angustifolius) in salmonid diets significantly decrease growth rates. This may be caused by the high concentrations of non‐starch polysaccharides including oligosaccharide (OS) in lupin. The antinutritive effects of OS have not yet been fully investigated in fish. The objective of this study was to determine the effect of enzyme supplementation of dehulled lupin‐based diets on the fish performance. There were two control diets: a fish meal‐based diet with no plant protein (FM) and a diet that contained 50% dehulled lupin (L). Four experimental diets based on diet L and containing four different exogenous enzyme supplements were used: diet L(E) (Energex); diet L(B) (Bio‐Feed Pro); diet L(α) (Alpha galactosidase); and diet L(Mix), which contained all the enzymes. Fish were randomly stocked into tanks in duplicate groups of 38 fish, 16.58±0.169 (SE) g, and were fed twice a day for 6 weeks. The supplemented enzymes did not improve weight gain in fish fed lupin‐based diets. However, mixed enzyme significantly improved Protein Efficiency Ratio (PER). Apparent digestibility of DM, CP and GE significantly improved in fish‐fed L(E) diet. None of the supplemented enzymes affected digestive tract indices or carcass composition. Surprisingly, weight gain was significantly higher in fish‐fed L(α), L(E) and L(Mix) diets as compared with FM diet. Feed intake was significantly higher in fish‐fed L, L(α) and L(E) diets compared with the FM diet. It is concluded that storing of lupin kernel under a suitable condition may have partially hidden the positive effects of exogenous enzymes through activating the endogenous enzymes.  相似文献   
52.
ABSTRACT The stem nematode Ditylenchus dipsaci is of great economic importance worldwide as a parasite of agricultural crops and horticultural plants. The internal transcribed spacer (ITS) of rDNA from 23 populations of the D. dipsaci complex from various host plants were amplified and sequenced. Seven previously studied populations were also included in the study. The phylogenetic analysis of the full ITS and ITS2 sequence alignments using minimum evolution, maximum parsimony, and Bayesian inference under the complex model of DNA evolution revealed trees with two main clades: (i) D. dipsaci sensu stricto with diploid chromosome numbers and comprising most isolates from agricultural, ornamental, and several wild plants, and (ii) Ditylenchus spp. with polyploid chromosome numbers, reproductively isolated from diploid populations, and subdivided into six subclades ("giant race" from Vicia faba, Ditylenchus species parasitizing various Asteraceae, and a Ditylenchus sp. from Plantago maritima). Using the energy minimization approach and comparative sequence analysis, it has been found that the secondary structure of ditylenchid ITS2 is organized in three main domains. The importance of knowledge on the RNA structure for phylogenetic analysis is discussed. Conventional polymerase chain reaction (PCR) and real-time PCR with SYBR green dye I with a species specific primer have been developed for detection and quantification of D. dipsaci sensu stricto Validation tests revealed a rather high correlation between real numbers of fourth-stage juveniles of the stem nematodes in a sample and expected numbers detected by real-time PCR. Problems of accuracy of quantification are discussed.  相似文献   
53.
54.
The main aim of this study was to evaluate methods for fixed area and distance sampling in the Zagros open forest area in western Iran.Basic forest management and planning required appropriate quantitative and qualitative information.Two sampling methods were compared on the basis of the actual means of characteristics derived from the 100 % survey.In total,37 sampling plots were systematically installed with a grid of 100 m 9 100 m in the study area.Density,crown canopy,and basal area of the stands were measured.The 100 % survey showed that tree density above 12.5 cm diameter at breast height was 68.04 stem ha~(-1),basal area was 15.16 m~2ha~(-1) and crown canopy percentage was 35.71 % ha~(-1).The values for the traits determined by the two sampling methods differed significantly(P=0.05).When the time required for the methods was compared,transect sampling required less than systematic-random sampling.Therefore,the transect sampling method was the more economical method for the Zagros open forests.The transect sampling method was statistically defensible and practical for quantitating characteristics of the Zagros open forests.  相似文献   
55.

Background

The aim of this study was to fabricate the poly caprolactone (PCL) aligned nanofiber scaffold and to evaluate the survival, adhesion, proliferation, and differentiation of rat hair follicle stem cells (HFSC) in the graft material using electrospun PCL nanofiber scaffold for tissue engineering applications.

Methods

The bulge region of rat whisker was isolated and cultured in DMEM: nutrient mixture F-12 supplemented with epidermal growth factor. The morphological and biological features of cultured bulge cells were observed by light microscopy using immunocytochemistry methods. Electrospinning was used for production of PCL nanofiber scaffolds. Scanning electron microscopy (SEM), 3-(4, 5-di-methylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, and histology analysis were used to investigate the cell morphology, viability, attachment and infiltration of the HFSC on the PCL nanofiber scaffolds.

Results

The results of the MTT assay showed cell viability and cell proliferation of the HFSC on PCL nanofiber scaffolds. SEM microscopy images indicated that HFSC are attached, proliferated and spread on PCL nanofiber scaffolds. Also, immunocytochemical analysis showed cell infiltration and cell differentiation on the scaffolds.

Conclusion

The results of this study reveal that PCL nanofiber scaffolds are suitable for cell culture, proliferation, differentiation and attachment. Furthermore, HFSC are attached and proliferated on PCL nanofiber scaffolds.Key Words: Nanofiber, Electrospinning, Stem cells, Tissue engineering  相似文献   
56.
Abstract: An 11‐year‐old spayed‐female German Shepherd dog was presented to the Veterinary Medical Teaching Hospital at Kansas State University with a history of weight loss, anorexia, depression, and lethargy for 2–3 weeks. Radiographic examination revealed a mass in the spleen and several round radiodense foci in the liver. CBC results included normocytic normochromic anemia, marked thrombocytopenia, and low numbers of neoplastic cells that frequently had cytoplasmic projections or blebs. A bone marrow aspirate contained about 80% neoplastic megakaryoblasts with the same microscopic features as those observed in peripheral blood. Using flow cytometry, cells of large size were identified in peripheral blood that expressed CD41/61, CD45, CD61, and CD62P (P‐selectin) and were negative for markers of T cells, B cells, monocyte/macrophages, and dendritic cells. Because of the poor prognosis, euthanasia and subsequently necropsy were performed. On histopathologic examination, neoplastic megakaryoblasts were identified in spleen, liver, mesenteric lymph node, and the pulmonary vasculature. Using immunohistochemistry, the neoplastic megakaryoblasts weakly expressed von Willebrand factor. Based on microscopic and immunophenotypic findings, a diagnosis of acute megakaryoblastic leukemia (AMegL) was made. To our knowledge, this is the first report of AMegL in a domestic animal in which immunophenotyping by flow cytometry and a panel of antibodies against CD41/61, CD61, and CD62P were used to support the diagnosis.  相似文献   
57.
58.
Abstract: Nonhuman primates (NHPs) are commonly used for biomedical research because of the high level of gene homology that underlies physiologic similarity to human beings. Malaria parasites of the genus Plasmodium cause one of the most frequent parasitic diseases of NHPs originating from tropical and subtropical areas and as such represent a significant research confounder. Malaria in NHPs presents a diagnostic challenge especially to those laboratories that see no more than a few malaria cases per year in NHPs. The accurate and timely diagnosis of malaria infection in NHPs facilitates the appropriate treatment of individuals infected with the malaria parasites. Conventional microscopy based on the examination of Giemsa‐stained thick and thin blood films remains the mainstay of laboratory diagnosis of malaria infection because of the high diagnostic sensitivity and specificity and also the capability for Plasmodium species identification and parasite counts. This procedure is recognized as technically difficult and time‐consuming, requiring considerable training to obtain the necessary skills. In the past few years, efforts to replace the traditional but tedious reading of blood films have led to different techniques for the detection of malaria parasites, including fluorescence microscopy, detection of intraleukocytic hemozoin or malaria pigment using automated blood cell analyzers, immunochromatographic rapid diagnostic tests based on malaria antigen detection, and PCR assays. These techniques offer new approaches for diagnosing malaria in NHPs. This review focuses on the available laboratory diagnostic tools for malaria in NHPs.  相似文献   
59.
A field experiment was carried out with a split plot arrangement based on a randomized complete block design with three replications in 2014. Triple super phosphate (0, 3.75, 7.5, 11.25 and 15 g m?2) was applied in main plots and phosphate bio-fertilizer (seed inoculation and topdressing) was allocated to sub plots. Results indicated that application of plants with phosphorus (P) bio-fertilizer as topdressing increased plant height and the number of the lateral branches under low levels of chemical P fertilizer, while plants from seed inoculated with P bio-fertilizer had more of those traits under high levels of chemical P fertilizer. Maximum leaf and flower dry weights were found under the lowest level of chemical P fertilizer. Moldavian balm plant demonstrated highly responsiveness to biological fertilizers in terms of increase in essential oil (EO) percentage and yield. It can be concluded that the effects of bio-fertilizer as seed inoculation is more during the early vegetative growth of plants. Thus, plants from seeds inoculated with P bio-fertilizer treatment had more biomass and EO percentage under high levels of chemical P fertilizer.  相似文献   
60.
This study was conducted to investigate the physico-chemical properties and antioxidant activity of five pomegranate fruit (Punica granatum L.) cultivars grown in Iran. Significant differences were found among the pomegranate cultivars for many of the properties studied. Results showed that, in particular, fruit diameter ranged from 63.63 mm (Syah) to 79.29 mm (Rabab), fruit volume from 153.3 cm3 (Syah) to 293.3 cm3 (Rabab), and fruit density from 0.93 g cm?3 (Rabab) to 1.13 g cm?3 (TorshSefeed). Although Syah showed the lowest fruit weight (144.8 g), fruit yield (8.28 ton ha?1), and fruit skin thickness (1.55 mm), Rabab had the highest fruit yield (27.1 ton ha?1) and fruit skin thickness (2.32 mm). Juice volume was found to vary between 61.1 and 67.0 cm3. Percent of aril ranged from 59.64% (Rabab) to 75.3% (Syah) and weight of aril between 108.9 and 199.8 g. Also, results indicated that titratable acidity content varied from 0.39% (Syah) to 1.13% (TorshSefeed). The total soluble solids content varied from 12.67 ?Brix (TorshSefeed) to 15.67 ?Brix (ZardehAnar), pH values from 3.05 to 3.77, Electrical conductivity values from 2.8 to 3.14 dS m?1, and vitamin C content from 59.25 to 69.52 mg 100 g?1. The anthocyanin content was observed to vary between 80.36 (Syah) and 216.97 (ZardehAnar). The antioxidant activity of pomegranate cultivars ranged from 27.24% (Syah) to 84.04% (TorshSefeed). These results demonstrated that the cultivar was the major factor which influences the morpho-pomological and chemical (especially, antioxidant activity) properties of pomegranates.  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