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   72篇
  免费   3篇
林业   13篇
农学   1篇
基础科学   2篇
  11篇
综合类   5篇
农作物   9篇
水产渔业   6篇
畜牧兽医   25篇
植物保护   3篇
  2022年   2篇
  2021年   1篇
  2020年   4篇
  2019年   4篇
  2018年   5篇
  2017年   7篇
  2016年   5篇
  2015年   2篇
  2014年   2篇
  2013年   5篇
  2012年   10篇
  2011年   6篇
  2010年   6篇
  2009年   1篇
  2008年   2篇
  2007年   3篇
  2006年   2篇
  2005年   6篇
  2003年   1篇
  2002年   1篇
排序方式: 共有75条查询结果,搜索用时 15 毫秒
51.
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   
52.
In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3‐aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pentamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g?1 of silica beads) of AgNO3 on the surface using chemical reduction. Ag/TEPA‐Den‐SiO2 samples were characterized by TEM, FE‐SEM/EDS, FT‐IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA‐Den‐SiO2 samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2 h contact period. Ag/TEPA‐Den‐SiO2 samples maintained their antibacterial activity after 14‐day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA‐Den‐SiO2 substrates could be effective antibacterial materials for disinfection of seawater used to culture Penaeid shrimp larvae.  相似文献   
53.
The study was conducted using a completely randomized design with five treatments each with three replicates. In each treatment, 30 fish (10 per replicate) with an average body weight of 30 ± 0.6 g were randomly allocated to 60‐L tanks. Treatments consisted of a control (a diet without rutin and oxytetracycline (OTC)), an OTC treatment (a diet free from rutin and containing 75 mg kg?1 body weight OTC) and the (OTC + rutin) treatments including diets with different levels of rutin, 500 (R‐500 + OTC), 1000 (R‐1000 + OTC) and 2000 (R‐2000 + OTC) ppm and 75 mg kg?1 body weight per day OTC which were fed to fish for 28 days. The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in the blood serum after the OTC treatment were significantly (P < 0.05) higher than in the control. After the three (OTC+rutin) treatments, the AST and ALT activities were not significantly different from the control. The level of glucose in the blood serum was significantly lower (P < 0.05) in all treatments as compared to the OTC treatment. Superoxide dismutase (SOD) and catalase (CAT) activities in red erythrocyte lysates were significantly (P < 0.05) reduced after OTC treatment in comparison with the control. After the three (OTC+rutin) treatments, the values of these indices were significantly (P < 0.05) higher than the OTC treatment, in particular for the R‐1000 + OTC treatment. It seems that rutin, as a non‐enzymatic inhibitor, is capable of preventing damage to the liver tissue and reducing oxidative stress.  相似文献   
54.
Persian Gulf cuttlefish mantles were hydrolyzed (CPH) using alcalase, and the optimal hydrolysis parameters were obtained for the highest degree of hydrolysis (DH) and strongest antioxidant (based on their ability to quench 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals) activity using response surface methodology (RSM). The predicted optimal parameters of DH and quenching DPPH radicals was: pH of 7.88, 50.2°C, 150 min, and enzyme to substrate ratio of 1.5%. The reducing power (RP) and ability of optimized peptides to quench ABTS radicals in a gastro-intestinal track model system increased during the intestinal stage, while scavenging ability against DPPH radicals dropped (P < 0.05). The oxidation of lipid was retarded in a lecithin-liposome model added with optimized CPH in a concentration dependent response. Ultrafiltration of optimized CPH showed that the 3–10 KDa fraction had the greatest DPPH radical scavenging activity, the 10–30 KDa fraction had the highest reducing power, and the <3 KDa fraction had the greatest ABTS radical scavenging activity.  相似文献   
55.
Overuse of the chemical compounds and toxic elements leads to problems and transmission of contaminants and pollutants to humans and other living organisms. One of the agricultural industries' byproducts is production of various composts from the organic raw materials and its best type is Vermicompost. In this study, effects of raw materials on qualitative and quantitative characteristics of vermicompost are discussed. To do so, sheep manure, pomegranate peels, spent mushroom compost either singly or double-, triple-, or four-fold chopped corn, sugar beet pulp, and sawdust were used. This research project was conducted in a completely randomized design experiment with 23 treatments with 3 replications. Results revealed that various bed combinations exert different effects on vermicompost quality such that the vermicomposting process led to a significant decrease in electrical conductivity and a significant increase in pH in most of the culture (seed) beds. Also, the levels of nitrogen, phosphorous, and potassium in most treatments increased following completion of the vermicomposting process. As a result, this process can be introduced as an organic fertilizer with complete nutrients for improving chemical characteristics of agricultural wastes to usable fertilizers.  相似文献   
56.
57.
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   
58.

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   
59.
This study was conducted to evaluate the Salvia officinalis hydroalcoholic extract on fertility capacity and behavioral features in rats exposed to immobilization stress. Male rats were randomly divided into five groups; Control; Stressed rats; and Stressed rats received 50, 100 and/or 200 mg/kg bw S. officinalis hydroalcoholic extract. To induce stress, rats were immobilized for 49 days and received S. officinalis extract orally. On day 56, we analyzed behavioral tests and evaluated reproduction capacity by measuring LH, FSH, and testosterone. Sperm parameters such as motility, viability, and total count were also determined. Bodyweight changes were also calculated on day 56. Male rats from different groups were mated with healthy female rats. Data showed that the use of 100 and 200 mg/kg bw S. officinalis extract in stressed rats increased bodyweight gain and improved behavioral disorders compared to control‐matched groups (p < .05). Besides, administration of 100 and 200 mg/kg bw S. officinalis extract had the potential to improve sperm parameters and fertility capacity in stressed rats (p < .05). Decreased testosterone levels were blunted in the stressed rats that received plant extract coincided with the reduction of LH and FSH compared to control‐matched stressed rats (p < .05). We found neutral effects in stressed rats that received 50 mg/kg bw plant extract. Collectively, the hydroalcoholic extract of S. officinalis could improve the fertility capacity and behavioral features under stressful conditions in a dose‐dependent manner.  相似文献   
60.
The purpose of oocyte in vitro maturation is generation of mature oocytes that could support future development. Efforts have been made to enhance oocyte developmental competence by developing optimal culture conditions. The present study is conducted to determine melatonin effects on quality of polycystic ovarian syndrome (PCOS) oocytes when it has been added during in vitro maturation, and immature oocytes were cultured in defined conditioned medium with and without different melatonin concentrations. Melatonin could significantly improve nuclear maturation of PCOS oocytes (81.1% vs. 56.3%, P < 0.05 were achieved with 10?6 mol/L concentration). Cleavage rate was significantly higher in 10?5 mol/L concentration compared to untreated oocytes in PCOS (54% vs. 35%, respectively) and it was significantly higher with 10?6 mol/L concentration in the control group, 55% versus 38%, compared to untreated oocytes. This study showed that melatonin has the potential to induce oocyte nuclear maturation and guarantee fertilization potential. © 2016 Japanese Society of Animal Science  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