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   740篇
  免费   55篇
  国内免费   60篇
林业   78篇
农学   49篇
基础科学   12篇
  101篇
综合类   88篇
农作物   66篇
水产渔业   130篇
畜牧兽医   218篇
园艺   29篇
植物保护   84篇
  2024年   4篇
  2023年   14篇
  2022年   18篇
  2021年   32篇
  2020年   20篇
  2019年   21篇
  2018年   38篇
  2017年   36篇
  2016年   30篇
  2015年   15篇
  2014年   26篇
  2013年   59篇
  2012年   46篇
  2011年   47篇
  2010年   43篇
  2009年   31篇
  2008年   43篇
  2007年   32篇
  2006年   22篇
  2005年   19篇
  2004年   16篇
  2003年   45篇
  2002年   63篇
  2001年   54篇
  2000年   36篇
  1999年   15篇
  1998年   8篇
  1997年   5篇
  1996年   3篇
  1995年   2篇
  1992年   1篇
  1989年   3篇
  1988年   2篇
  1985年   1篇
  1982年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1965年   1篇
排序方式: 共有855条查询结果,搜索用时 0 毫秒
61.
儿茶素在家兔体内的药物动力学及生物利用度研究   总被引:1,自引:0,他引:1  
对家兔单剂量静注和灌服儿茶素 (Catechin) 2 5mg/kg体重各 5只。用高效液相色谱法测定其血药浓度。房室模型分析表明静注给药后的药时数据符合无吸收二室开放模型 ,主要动力学参数为 :t1 / 2α=( 0 .1 5± 0 .0 1 )h ,t1 / 2 β=( 0 .5 8± 0 .0 2 )h ,Vc=( 1 .41± 0 .0 8)L ,Vβ=( 2 .97±0 .1 1 )L ,ClB=( 3.5 3± 0 .1 0 )L/h ,AUC =( 1 6.95± 1 .5 2 )mg/(L·h)。灌服儿茶素的药时数据符合一级吸收一室开放模型 ,主要药物动力学参数为 :t1 / 2Ka=( 0 .39± 0 .0 6)h ,t1 / 2Ke=( 0 .79±0 .1 1 )h ,tmax=( 0 .78± 0 .1 1 )h ,Cmax=( 3.35± 0 .1 6)mg/L ,AUC =( 7.45± 0 .94)mg/(L·h) ,F =( 4 4.1 8± 3.5 9) %。儿茶素在健康家兔体内的药动学特征是 :吸收迅速 ,达峰时间短 ,消除快 ,半衰期短 ,表观分布容积较大 ,口服摄入吸收不完全  相似文献   
62.

In this study, we aimed to determine the basic food components, fatty acids and amino acids, and variations in these components with months in goldband goatfish (Upeneus moluccensis) that fishing from Gulf of Antalya. As a result of the analyzes, the crude fat values were determined between 1.43 and 3.78%, and the crude protein values were determined between 20.79 and 22.16%. The most abundant fatty acids were determined: palmitic acid (C16:0), stearic acid (C18:0), palmitoleic acid (C16:1c9), oleic acid (C18:1c9), linoleic acid (C18:2n-6), eicosatrienoic acid (C20:3n-3), arachidonic acid (C20:4n-6), eicosapentaenoic acid (C20:5n-3), docosapentaenoic acid (C22:5n-6), and docosahexaenoic acid (C22:6n-3). The most abundant amino acids were determined lysine and leucine, aspartic acid, glutamic acid, alanine, and glycine. The differentiations of essential nutrient components, fatty acids, and amino acids were found generally significant (P < 0.05).

  相似文献   
63.
In this study, supplementation of two levels (5 and 25 parts per million; ppm) of boron into broiler diets including 125 IU kg(-1) (inadequate) and 2000 IU kg(-1) (adequate) vitamin D3 was investigated. The effects of supplementation on performance and biochemical characters (Ca, P, Mg, glucose and AP) of broilers from 1 to 45 days of age were evaluated. Boron provided significant increases in performances of chicks fed both adequate and inadequate vitamin D3-containing diets. The improvements in the inadequate vitamin D3-containing group were higher than that of adequate vitamin D3-containing group. The boron addition had a positive effect on Ca, P and alkaline phosphatase levels of chicks. Boron might be regarded as beneficial in inadequate vitamin D3-containing broiler feed.  相似文献   
64.
The study describes basic structural aspects of the integumental layers (epidermis, dermis, hypodermis) of the Turkish Angora goat. The results have been obtained by light- and electronmicroscopical methods. Central topics are measurements of layer thickness as related to annual season and life period, as well as typical criteria of integumental layer construction as connected with the hair cycle. Remarkable is a trimerous organization of the dermis and cyclic changes in the thickness of the stratum adiposum of the hypodermis. The findings are discussed with regard to comparable observations from other domestic mammals.  相似文献   
65.
In this study, the effects of nitroscanate were investigated in naturally acquired Hymenolepis nana infections in rats and mice. The natural infection was determined by centrifugal flotation technique of faeces. The infected rats and mice were divided into two treatment and two control groups (N = 10). Nitroscanate at the dose of 50 mg/kg per day was given in the diet for 4 days. The rats and mice of treatment groups were necropsied on 7th day after the last treatment together with those of control groups. Following necrospsy, in the treatment group a geometric mean of 1.07 Hymenolepis nana were recovered out of ten mice, compared with 8.14 in the control group. In the rat treatment group no Hymenolepis nana were found in ten rats, while the control group showed a geometric mean of 6.23. Nitroscanate was found to be effective 100% and 86.8% at the treatment of H. nana infection in rats and mice respectively.  相似文献   
66.
67.
Equine adenovirus type 1 (EAdV-1) is a cause of repiratory tract infection in equids. In present study for the first time in Turkey, the prevalence of EAdV-1 in nasal swab samples obtained from horses showing respiratory symptoms was investigated by polymerase chain reaction (PCR), and molecular characterization of the hexon gene detected in the Turkish (TR) strain was performed. Overall, the prevalence of EAdV-1 was found low (1.4%) as indicated by a positive PCR reaction from the nasal swab extracts tested. Phylogenetic analysis based on the partial sequences of the hexon gene of a TR-EAdV-1 strain with those of previously isolated AdVs from different mammals and an EAdV-1 M1 strain showed that the EAdV-1 strains were placed into a unique cluster. Although the TR-EAdV-1 strain was closely related to CAV-1, CAV-2 and bat adenovirus reference strains, larger-scale studies are necessary to better understand the molecular epidemiology and population structure of EAdV-1 in Turkey.  相似文献   
68.
The efforts to mitigate CO2, one of the greenhouse gases causing global warming and climate change problems, have an important place in the worldwide agenda. One of the factors that cause CO2 emissions is energy use in residential buildings, hence urban residential use is one of the areas on which mitigation efforts are focused. As land use planning determines the spatial development, density and form of residential areas, it has a direct role in the formation of residential emissions. However, these efforts to mitigate emissions could not yet be integrated with land use planning. It is possible to list the reasons as the mitigation efforts are made either on the building scale (mitigation of residential emissions by technological–architectural solutions) or on a global–regional scale (development of carbon sinks), the focus on transportation sector, and in land use planning, lack of considering the potential of urban green areas to mitigate emissions. By taking into consideration the O2 production potential of green areas, a method proposal for land use planning is developed in this study to maintain the carbon–oxygen balance in residential areas. Depending on the form and density of the residential areas developed in a plan, the necessary size of green areas in such a plan is estimated by the method proposed. The varying emission amounts in different residential areas with diverse housing types, the number of actively used residential units, and local vegetation differences are included in the estimate. Therefore, an estimation method proposal that could be easily used in land use planning and that considers local differences is presented in the paper.  相似文献   
69.

The genus Brucella causes significant economic losses due to infertility, abortion, stillbirth or weak calves, and neonatal mortality in livestock. Brucellosis is still a zoonosis of public health importance worldwide. In the past, vaccination was administered subcutaneously and nowadays, the conjunctival vaccine is administered. There is no definite information about the changes of the biochemical parameters and antibody response after conjunctival vaccination. In this study, the investigation of the changes in the levels of some biochemical parameters due to the conjunctival vaccination for brucellosis was aimed. Thirty sheep were used as an animal material. The vaccine was done single dose against Brucella melitensis and the blood was drawled from Vena jugularis during 4 months. Antibody levels were determined by serum tube agglutination test. Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), glucose, total protein, and albumin levels were measured using commercial autoanalyzer in sera. The antibody titers (p?<?0.001) increased significantly at first month compared to the pre-vaccination, but at the second month began to fall. There was no statistically significant changes in glucose, AST, ALT activity after vaccination (p?>?0.005). The significant amount of total protein and ALP decreased after vaccination (p?<?0.005). LDH levels and total protein levels were significantly increased (p?<?0.005). In conclusion, conjunctival vaccine was considered to be used as a safe to protect the sheep from brucellosis and the results of the study may be used to improve the efficiency of brucellosis eradication programs within livestock management.

  相似文献   
70.
This study was conducted in 2007 and 2008 in order to determine the effects of irrigation frequency on the yield and quality parameters of dwarf trees of the apple cultivar ‘Gala, Galaxy’ in the first and second year of cultivation. Irrigation water was applied at 3?, 5?, 7?, and 10-day intervals as much as the amount of water consumed from the field capacity. Statistical analysis revealed that the effects of irrigation frequency on yield were significant. Since the trees used in the experiment showed mainly vegetative growth, the effects of irrigation frequency on the fruit quality characteristics varied. Irrigation water amount was applied as 355.7–446.5 mm and 359.2–538.9 mm to the experimental treatments in 2007 and 2008, respectively. The evapotranspiration measured was in the range 400.7–491.5 mm in 2007 but in the range 440.2–600.5 mm in 2008, while the yields in the same years ranged from 1.54 to 2.84 t ha?1 and from 2.61 to 6.06 t ha?1. Water use efficiency varied between 2.40 and 4.80 t ha?1mm?1 in the first year of the experiment but between 3.45 and 7.08 t ha?1mm?1 in the second year. The I2 treatment, in which the highest yield and water use efficiency were recorded in both years of the experiment under the experimental conditions, was determined as the irrigation scheduling.  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