全文获取类型
收费全文 | 487篇 |
免费 | 43篇 |
专业分类
林业 | 48篇 |
农学 | 23篇 |
基础科学 | 9篇 |
79篇 | |
综合类 | 16篇 |
农作物 | 123篇 |
水产渔业 | 100篇 |
畜牧兽医 | 99篇 |
园艺 | 9篇 |
植物保护 | 24篇 |
出版年
2023年 | 4篇 |
2022年 | 19篇 |
2021年 | 24篇 |
2020年 | 17篇 |
2019年 | 33篇 |
2018年 | 47篇 |
2017年 | 46篇 |
2016年 | 46篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 66篇 |
2012年 | 28篇 |
2011年 | 49篇 |
2010年 | 19篇 |
2009年 | 10篇 |
2008年 | 33篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 2篇 |
1995年 | 1篇 |
1994年 | 4篇 |
排序方式: 共有530条查询结果,搜索用时 31 毫秒
11.
Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates 总被引:4,自引:0,他引:4
Mahdi Gheysari Seyed Majid Mirlatifi Mehdi Homaee Gerrit Hoogenboom 《Agricultural Water Management》2009,96(6):946-954
Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO3) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO3-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha−1), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO3-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO3-N leaching out of the 60-cm soil layer was 8.43 kg N ha−1, for the 142 kg N ha−1 and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO3 concentration at the 60 cm depth was 46 and 138 mg l−1, respectively. Based on our findings, it is possible to control NO3 leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management. 相似文献
12.
Latifeh Abdellahi Fariba Iraji Anahita Mahmoudabadi Seyed Hossein Hejazi 《Iranian Biomedical Journal》2022,26(1):1
Leishmaniasis is caused by protozoan Leishmania parasites that are transmitted through female sandfly bites. The disease is predominantly endemic to the tropics and semi-tropics and has been reported in more than 98 countries. Due to the side effects of anti-Leishmania drugs and the emergence of drug-resistant isolates, there is currently no encouraging prospect of introducing an effective therapy for the disease. Hence, it seems that the key to disease control management is the introduction of an effective vaccine, particularly against its cutaneous form. Advances in understanding underlying immune mechanisms are feasibale using a variety of candidate antigens, including attenuated live parasites, crude antigens, pure or recombinant Leishmania proteins, Leishmania genes encoding protective proteins, as well as immune system activators from the saliva of parasite vectors. However, there is still no vaccine against different types of human leishmaniasis. In this study, we review the works conducted or being performed in this field. Key Words: Immune response, Leishmaniasis, Vaccination 相似文献
13.
Dehghan Marzieh Balouchi Hamidreza Yadavi Alireza 《Journal of Crop Science and Biotechnology》2020,23(2):137-148
Journal of Crop Science and Biotechnology - Irrigation interruption owing to time of incidence is affecting the seed quality. The aim of this research was to determine whether the brassinolide and... 相似文献
14.
15.
Afshin Raoofi DVM DVSc Seyed Hossein Mardjanmehr DVM PhD Majid Masoudifard DVM DVSc Farajollah Adibhashemi DVM DVSc Peyman Asadian DVM PhD 《Journal of Equine Veterinary Science》2006,26(12):588-591
A 4-year-old crossbred Thoroughbred mare was referred to the University of Tehran Veterinary Medical Teaching Hospital for evaluation of a mass in the pelvic cavity. The mare had been partially anorectic and pyrexic. On clinical examination, the mare was thin and depressed, with body temperature of 38°C, a pulse rate of 38 beats/minute, and a respiratory rate of 10 breaths/minute. Palpation per rectum revealed a large, smooth and tense mass in the anterior part of the pelvic cavity. Ultrasound examination confirmed the presence of a soft tissue mass with a thick wall. The inner surface of the mass had a villous-like appearance. The stroma of the mass was mottled, with accumulation of speckled and hypoechoic to slightly hyperechoic fluid. Hormone assays revealed low serum concentration of testosterone. Serum progesterone concentration indicated that active luteal tissue and serum estradiol concentration was 24 pg/ml. On histological examination, the sections from the tumor were composed of oval- or spindle-shaped cells loosely arranged in diffuse sheets or irregularly interlacing fascicles. On the basis of these histological findings, the large tumor mass of the left ovary was considered to be a thecoma. To our knowledge, the details of the clinical, ultrasonographic, endocrinologic, and histologic findings of this tumor in the mare have not been described in the veterinary literature. 相似文献
16.
Pomegranate fruit is an important source of potentially healthy bioactive compounds and mineral nutrients. Changes in total phenolic compound, concentrations, and levels of macronutrients (P, K, N, Mg, Ca and Na) and micronutrients (Zn, Cu, Mn, Fe and B) in arils and peel of pomegranate fruit were recorded from 10 days after full bloom until harvest. Total phenolics levels increased at early stage of growth both in peel and arils of fruit, but thereafter generally decreased during maturation and reached to 3.70 and 50.22 mg g−1 of dry weight in arils and peel, respectively, at harvest. The amount of total phenolics in peel was markedly higher than arils of pomegranate fruit. The concentration of most elements in arils and peel decreased during fruit growth and development. At harvest the relative order of concentration of macronutrients both in arils and peel was K > N > Ca > P > Mg > Na. The concentration of most micronutrients was greater in the arils than in the peel especially in early season. The relative order of concentration of micronutrients in arils was B > Fe > Zn > Cu > Mn. The accumulation of all the macro- and microelement within the fruit also increased during fruit growth and development. These results provide important data on total phenolics and macro- and micronutrient changes during fruit growth and development, emphasizing that pomegranate fruit can be a good source of bioactive compounds and minerals. 相似文献
17.
Khazaeel Kaveh Pesarakli Hamid Mashhadi Alireza Ghadrdan Borujeni Mahdi Pourmahdi 《Veterinary research communications》2022,46(2):405-417
Veterinary Research Communications - Accurate estimation of a horse's age based on the condition of the tooth status is necessary as a scientific and artistic technique, which has not been... 相似文献
18.
Seyed Abdolkhalegh Yadegarnejad Mehdi Dylam Jafarabad Najmeh Mohammadi Savadkoohi 《林业研究》2015,26(2):425-434
Wildfires in recent years have resulted in degradation and damage to the Hyrcanian forest ecosystems in Northern Iran.This study was carried out to investigate fire damage to trees and changes in regeneration in early-season growth after wildfires in the Golestan Province.For this purpose,a random sampling plan was used,with 60 circular plots(each plot is 1000 m2) for each stand and 240 circular(25 m2) plots for regeneration within the burned and unburned areas,respectively.In each plot,habitat factors were recorded,including crown canopy percentage,forest stratum,herb-layer cover percentage,species,diameter at breast height,tree and regeneration quality,and quantity of seedlings and saplings.Our results showed that bark is an important factor for fire resistance in Hyrcanian forests.The Persian ironwood and European yew has the highest and lowest fire resistance;as broad leave species are more resistant than needle leaf species.Density of regeneration in unburned area was higher than burned area,and statistical analysis showed significant differences for all species between two areas.Fire effects on sapling were different among species which indicates sapling has different resistance to fire.Forest floor fuel,season,stand composition and microclimate have more effects on fire severity while environmental factors,regeneration and management practices shaping future composition stands. 相似文献
19.
Effect of different levels of dietary sweet orange (Citrus sinensis) peel extract on humoral immune system responses in broiler chickens
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zohreh Pourhossein Ali Ahmad Alaw Qotbi Alireza Seidavi Vito Laudadio Gerardo Centoducati Vincenzo Tufarelli 《Animal Science Journal》2015,86(1):105-110
This experiment was conducted to evaluate the effects of different levels of sweet orange (Citrus sinensis) peel extract (SOPE) on humoral immune system responses in broiler chickens. Three hundred 1‐day broilers (Ross‐308) were randomly allocated to treatments varying in supplemental SOPE added in the drinking water. The experimental groups consisted of three treatments fed for 42 days as follows: a control treatment without feed extract, a treatment containing 1000 ppm of SOPE and a treatment containing 1250 ppm of SOPE. All treatments were isocaloric and isonitrogenous. Broilers were vaccinated with Newcastle disease virus (NDV), avian influenza (AI), infectious bursal disease (IBD) and infectious bronchitis virus (IBV) vaccines. Antibody titer response to sheep red blood cells (SRBC) was higher in the group fed 1250 ppm of SOPE (P < 0.05) as well as for immunoglobulin G (IgG) and IgM. Similarly, antibody titer responses to all vaccines were constantly elevated (P < 0.05) by SOPE enrichment in a dose‐dependent manner. Relative weights of spleen and bursa of Fabricius were unaffected by treatments. Dietary SOPE supplementation may improve the immune response and diseases resistance, indicating that it can constitute a useful additive in broiler feeding. Thus, supplying SOPE in rations may help to improve relative immune response in broiler chickens. 相似文献
20.
BACKGROUND: Adenoviruses are used extensively to deliver genes into mammalian cells, particularly where there is a requirement for high-level expression of transgene products in cultured cells, or for use as recombinant viral vaccines or in gene therapy. In spite of their usefulness, the construction of adenoviral vectors (AdV) is a cumbersome and lengthy process that is not readily amenable to the generation of large collection of clones. METHODS: In this project, to delete E1 gene in adenovirus, an adenoviral plasmid containing lateral sites of E1 region of adenovirus was made and recombination in the 293A cells between the homologous region of this linearized plasmid and the adenovirus genome resulted in the formation of the complete adenoviral recombinant. RESULTS: This recombination resulted in loss of E1 region and we constructed a recombinant adenovirus type 5 vector that E1 gene was deleted by homologous recombination. CONCLUSION: Homologous recombination is more easy and fast technique in the production of AdV. 相似文献