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   250篇
  免费   7篇
  国内免费   1篇
林业   30篇
农学   14篇
基础科学   1篇
  35篇
综合类   24篇
农作物   18篇
水产渔业   22篇
畜牧兽医   76篇
园艺   18篇
植物保护   20篇
  2022年   9篇
  2021年   7篇
  2020年   4篇
  2019年   8篇
  2018年   11篇
  2017年   12篇
  2016年   7篇
  2015年   5篇
  2014年   6篇
  2013年   23篇
  2012年   9篇
  2011年   13篇
  2010年   13篇
  2009年   12篇
  2008年   14篇
  2007年   6篇
  2006年   7篇
  2005年   6篇
  2004年   5篇
  2003年   3篇
  2002年   5篇
  2001年   2篇
  2000年   2篇
  1999年   6篇
  1997年   2篇
  1995年   3篇
  1994年   2篇
  1992年   3篇
  1991年   2篇
  1990年   4篇
  1989年   1篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1984年   1篇
  1983年   1篇
  1981年   4篇
  1980年   6篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1976年   3篇
  1975年   2篇
  1974年   1篇
  1972年   1篇
  1971年   1篇
  1970年   4篇
  1969年   1篇
  1967年   3篇
  1946年   1篇
排序方式: 共有258条查询结果,搜索用时 15 毫秒
251.
ABSTRACT

Vermicomposting is the processing of organic substrates through digestion by worms, usually Eisenia foetida. The physico-chemical characteristics of the substrates and health of the worms are important parameter for effective vermicomposting. This study assessed reproduction efficiency and reproductive rate of E. foetida and changes in EC, pH, organic C, total Nitrogen and C:N ratio by vermicomposting different substrate mixtures. The study was performed as a completely randomized design with 10 treatments and 4 replicates. Manures from sheep and horse were tested alone and mixed at 50 and 75% with residues of alfalfa and wheat straw. Wheat straw was also tested alone and mixed at 75% with 25% chicken manure. E. foetida were added to the mixtures and allowed to process the substrate mixtures for three months. Final EC, pH, organic C and N levels of vermicompost were measured, as well as the reproductive efficiency and reproductive rate of the E. foetida. All measured characteristics of the finished vermicompost were significantly different depending on substrate. Substrates also changed to differing degrees during vermicomposting. Total C and EC increased in all substrates; and pH, total N, and C:N decreased in all substrates during vermicomposting The greatest change of EC was in the 25% alfalfa + 75% sheep manure mixture, which was 12.8 dS.m-1 initially and 18.6 dS.m-1 in finished vermicompost. Overall, pH declined and EC increased during the preparing of vermicompost.  相似文献   
252.
Comparative studies on the influence of sprinkler irrigation and chemical control on Tetranychid mites infesting peanut The application of water to peanut plants using sprinkler irrigation systems showed a depressing effect on mite densities. Since the upper surface of the leaves are appreciably wetted, few numbers ofT arabicus (Attiah) andT. cucurbitacearum (Sayed) inhabit only the lower leaves surface. Data showed that spider mite populations on sprinkled plot were lower than those on acaricide treated plot and control plot.  相似文献   
253.
从胡杨生存的干旱强光照逆境中获得新的细菌资源,从中筛选新的可抑制瓜列当种子萌发的生防菌。采用3种分离培养基,以稀释涂布法对塔里木河流域3处胡杨根系样品进行可培养细菌分离,通过分析分离菌株16S rRNA基因序列确定其种属分类。采用皿内培养法测定其对瓜列当种子萌发的抑制活性,利用盆栽试验检测分离菌株M2-3对瓜列当寄生的防治效果。结果分离获得98株细菌,分属于28个属,马赛菌属Massilia、Pontibacter、玫瑰单胞菌属Roseomonas为优势菌属。其中,菌株M2-3与Pontibacter salisaro HMC5104T的相似度最高,为97.92%,其菌体发酵液10倍稀释液对瓜列当种子萌发抑制率为87.8%,盆栽试验表明该菌株对瓜列当防效可达36.9%,具备进一步开发可能性。  相似文献   
254.
This study investigated consumers’ motivations and perceptions of fish obtained from different production methods, namely wild or farmed. Data were collected from 526 consumers via face-to-face interviews in the seven regions of Turkey. A logistic regression model was designed for the consumers of different fish production methods. Results of the study demonstrate that consumers perceive wild and farmed fish differently. Furthermore, consumers have different perceptions of the following factors that also effect consumption: convenience, variety, origin, confidence, accessibility, freshness, and reliability.  相似文献   
255.
This study was conducted to assess the genetic basis and develop a regression model for a QTL trait, fruit setting of a full sib population of 164 hybrids obtained between ‘Clementine’ mandarin (Citrus reticulata Blanco ‘Clementine) and ‘Orlando’ tangelo’ (Citrus paradisi Macf. ‘Duncan’ × C. reticulata Blanco ‘Dancy’). Fruit setting of a 164 full sib population field-planted in 2007 was evaluated by visual counting of fruits in 2008, 2009, and 2010. We estimated linkage groups and effects of QTLs by using MapQTL5. Based on interval mapping, seven linkage groups of the maternal and eight linkage groups of the paternal maps harboured QTLs of the fruits setting, covering a total 300 of 1744 cM Citrus map. Only three segments were associated with all three-year data (one in ‘Clementine’ and two in ‘Orlando’ map) spanning 60 cM of 1744 cM of Citrus linkage map. Twenty-seven (17%) and 13 (8%) hybrids consistently produced less than 5 fruits and the highest number of fruits (≥50) in their 2nd, 3rd, and 4th ages. Based on BACKWARD elimination procedure of PROC REG option nested in SAS program, regression models constructed for 2008, 2009, and 2010s fruit setting explained 35, 81, and 38% of the total phenotypic variation (R2) observed in the 164 full-sib hybrids, respectively (P ≤ 0.05). This study indicated that early fruit setting was a complex trait affected by many QTLs and the regression model developed in this study might be used to predict performances of hybrids with similar genetic background.  相似文献   
256.
Extreme high-temperature stress (HTS) associated with climate change poses potential threats to wheat grain yield and quality. Wheat grain protein concentration...  相似文献   
257.
ABSTRACT

1. The real burden of Campylobacter spp. in Lebanon is still unknown. The aims of this study were to unravel the epidemiology of Campylobacter spp. in broilers at slaughterhouses in Tripoli, North of Lebanon and to characterise their antibiotic resistance profiles.

2. From May to November 2015, sampling was performed through five repeated surveys from 15 slaughterhouses that sold chicken directly to Lebanese customers. Isolates were subjected to pulsed field gel electrophoresis (PFGE) and flaA-restriction fragment length polymorphism (flaA-RFLP).

3. All investigated slaughterhouses were found to be positive for Campylobacter spp. Campylobacter coli was the predominant species (38 isolates) followed by C. jejuni (eight isolates). A noticeable level of resistance was detected among isolates against ciprofloxacin (97% of C. coli and 87.5% of C. jejuni), amoxicillin (89% of C. coli and 75% of C. jejuni), gentamicin (79% of C. coli and 50% of C. jejuni), and co-amoxiclav (24% of C. coli and 25% of C. jejuni). Erythromycin and ertapenem resistance were observed only in C. coli with the following percentages 74% and 13% respectively, but not in C. jejuni. PFGE and flaA-RFLP using DdeI as restriction enzyme divided the strains into 27 and 25 types respectively.

4. The high observed genetic diversity of Campylobacter spp. revealed the complexity of the spread of this genus in broilers. This study highlighted the pressing need to monitor antibiotic resistance and to ensure food safety from ‘farm to fork’ in Lebanon.  相似文献   
258.
In this study, volume density of white matter and grey matter areas of cervical segment of spinal cord in adult geese weighing 3–4 kg was examined using stereological methods. 10 geese were used as material without sex discrimination. All animals underwent perfusion with 10% buffered formaldehyde. Following the perfusion, animals were kept in 10% formaldehyde for 1 week. Geese were then dissected. Cervical area of spinal cord was revealed removing cervical spine. Tissue samples were obtained from each segment of cervical area. 5 μm thick cross‐sections were taken from these tissue samples via microtome. Series of cross‐sections were obtained by sampling in the ratio of 1/250 including 12 cross‐sections from each cervical segment of every animal. Cross‐sections were stained by haematoxylin eosin. They were photographed under microscope. Volume density (volume fractions) of both whole tissue and white matter and grey matter parts in each cervical segment of spinal cord were calculated using Cavalieri’s Principle. In the study, total volume of cervical segment, volume of white matter and grey matter, and ratios of these volumes one another were assessed in goose.  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