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   158篇
  免费   12篇
  国内免费   2篇
林业   4篇
农学   4篇
基础科学   1篇
  16篇
综合类   6篇
农作物   4篇
水产渔业   18篇
畜牧兽医   109篇
园艺   2篇
植物保护   8篇
  2024年   1篇
  2023年   1篇
  2021年   5篇
  2020年   6篇
  2019年   4篇
  2018年   2篇
  2017年   4篇
  2016年   9篇
  2015年   3篇
  2014年   6篇
  2013年   8篇
  2012年   9篇
  2011年   16篇
  2010年   3篇
  2009年   8篇
  2008年   8篇
  2007年   7篇
  2006年   9篇
  2005年   5篇
  2004年   11篇
  2003年   3篇
  2002年   5篇
  2001年   1篇
  2000年   2篇
  1999年   2篇
  1998年   6篇
  1997年   5篇
  1996年   1篇
  1995年   3篇
  1994年   3篇
  1993年   6篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
排序方式: 共有172条查询结果,搜索用时 859 毫秒
51.
The Rio Grande do Sul state, in Southern Brazil, is one of the foci of human cystic echinococcosis (CE). The sheep strain (G1) of Echinococcus granulosus and Echinococcus ortleppi (also known as cattle strain G5) have been reported before to infect livestock. However, up to the present, no molecular data are available on isolates of the E. granulosus complex from humans and dogs. The present study analyzed hydatid cysts from 6 CE patients and adult worms from 12 dogs. Sequencing of the mitochondrial cox1 and 12S rRNA genes detected the E. granulosus G1 genotype from four human cases, the G3 genotype (or buffalo strain) from one human case and E. ortleppi from another human case, respectively. Ten of the twelve dogs were found infected with the G1 genotype, and one dog each harbored worms of the G3 genotype and E. ortleppi. Obvious morphological differences were recognized between the G1 and E. ortleppi adult worms from dogs in this region. The buffalo strain (G3) is for the first time reported from South America.  相似文献   
52.
The usefulness of molecular absorption was investigated for the determination of total sulfur (S) in agricultural samples by high-resolution continuum source flame molecular absorption spectrometry. The lines for CS at 257.595, 257.958, and 258.056 nm and for SH at 323.658, 324.064, and 327.990 nm were evaluated. Figures of merit, such as linear dynamic range, sensitivity, linear correlation, characteristic concentration, limit of detection, and precision, were established. For selected CS lines, wavelength-integrated absorbance equivalent to 3 pixels, analytical curves in the 100-2500 mg L(-1) (257.595 nm), 250-2000 mg L(-1) (257.958 nm), and 250-5000 mg L(-1) (258.056 nm) ranges with a linear correlation coefficient better than 0.9980 were obtained. Results were in agreement at a 95% confidence level (paired t test) with those obtained by gravimetry. Recoveries of S in fungicide and fertilizer samples were within the 84-109% range, and the relative standard deviation (n=12) was typically <5%.  相似文献   
53.
The objective of this study was to evaluate if spray dried porcine plasma (SDPP) containing porcine circovirus type 2 (PCV2) genome supplemented in feed could transmit PCV2 to pigs challenged with porcine reproductive and respiratory syndrome virus (PRRSV). Twenty-three PRRSV-free pigs, non-viraemic for PCV2, were housed in bio-safety level 3 facilities and assigned to four groups in a 2×2 factorial design consisting of PRRSV challenge and a negative control. The diet contained 0 or 8kg SDPP per 100kg of feed. PRRSV challenge groups were inoculated intranasally with 2mL of a suspension containing 10(6) TCID(50)/mL PRRSV. The SDPP used in the study contained 7.56×10(5) PCV2 genome copies per gram. Dietary treatments were fed from 4days prior to PRRSV inoculation until 28days post-inoculation (PI). All challenged pigs developed PRRSV viraemia by day 3PI and PRRSV antibodies were detected in sera by day 14PI, with no difference between diet treatments. Neither PRRSV viraemia nor seroconversion was observed in non-challenged pigs. PCV2 was not detected in the serum of any pigs throughout the experimental period. SDPP containing the PCV2 genome supplemented in feed did not result in PCV2 transmission to either healthy or PRRSV-infected pigs under these experimental conditions.  相似文献   
54.
SUMMARY Subclinical nutritional myopathy was induced in 5-month-old sheep by feeding them a diet low in vitamin E and selenium. Subsequently clinical myopathy was induced by dosing with protected polyunsaturated fatty acids. Plasma activities of creatine kinase (CK), pyruvate kinase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase and aldolase, enzymes of muscle origin, all remained above their reference ranges in clinically affected sheep, but fluctuated widely. Similar fluctuations occurred in subclinically affected animals, resulting in some activities being within the reference ranges and some above, at different times. Plasma malondialdehyde, an indicator of lipid peroxidation, proved of no diagnostic value. Terminal plasma CK activities were significantly correlated with microscopic damage in the vastus lateralis (VL), but not the vastus intermedius (VI) or the tensor fascia lata (TFL) muscles. AST was the most highly correlated with damage in VI and VL. In two clinically affected sheep successfully treated with an oral dose of α-tocopherol actetate all enzymes decreased steadily to within their reference ranges, at rates probably related to their plasma half-lives. These results suggest that measurement of plasma CK activity would be useful in monitoring recovery of treated sheep.  相似文献   
55.
Objective To determine whether a drug detected in the blood or urine of a racing animal could have penetrated through the skin from a topically applied preparation.
Design Blood and urine of dogs and horses were analysed after topical administration of three common nonsteroidal anti-inflammatory preparations.
Experimental method Dimethylsulphoxide was analysed using a gas chromatograph with a flame photometric detector. Phenylbutazone, its metabolites and lignocaine were analysed using a gas chromatograph with a mass selective detector.
Results Dimethylsulphoxide, phenylbutazone and ligno-caine were detected in dog urine after muliple applications of the preparations. The maximum concentration of dimethyl-sulphoxide in dog urine correlated with the concentration of dimethylsulphoxide in the preparation. Phenylbutazone penetrated the skin more effectively from the cream than from the solution or gel preparations. This penetration was independent of the concentration of dimethylsulphoxide.
Conclusion The superior penetration of phenylbutazone from the cream can be explained by it being present as a neutral molecule in an hydrophobic medium. It is proposed that phenylbutazone penetrates the skin of greyhounds most effectively by a hydrophobic lipid route which is likely to be different from the path by which dimethylsulphoxide penetrates the skin.  相似文献   
56.
57.
58.
The notion that postweaning multisystemic wasting syndrome (PMWS)-affected pigs develop an impaired humoral response against porcine circovirus type 2 (PCV2) has been reported in several studies. However, little information is available regarding the presence of neutralizing antibodies (NA) in PCV2-infected pigs and their role in the pathogenesis of the disease. The aim of the present work was to further characterize the humoral response, and in particular the production of NA, in pigs with different PCV2-infection status. Seventy-two conventional pigs from different farms were classified into three groups based on PCV2 infection and clinico-pathological status, namely: PCV2-negative, non-PMWS PCV2-positive and PMWS-affected animals. In addition, 9-week old pigs from an experimental infection (6 controls and 14 PCV2-inoculated pigs) were also studied. NA and total PCV2 antibodies (TA) as well as viral load in serum were determined and correlated with the clinico-pathological status of pigs. Results indicated that PMWS-affected pigs had lower NA titres, if any, than healthy animals. NA titres were also inversely correlated with PCV2 load in serum. NA and TA titres were positively correlated; however, correlation differed among infection status, being lower in PCV2-positive pigs. Also, the diagnostic performance of each test was evaluated, indicating that the combination of viral neutralization and quantitative PCR in serum was useful to discard PMWS (specificity 92%). In experimentally infected animals, the evolution of NA paralleled the course TA, although a slight delay in NA production was seen in some animals. The increase of NA coincided with the drop in viral load. Results from this work further support that PMWS-affected pigs show an impaired humoral immune response and, particularly, an inefficient NA response against PCV2.  相似文献   
59.
60.
This study assessed the relationships between external K+ supply and K+ : Na+ ratios associated with Na+ toxicity in Jatropha curcas. Plants were exposed to increasing external K+ concentrations (6.25, 12.5, 25, 37.5, and 50 mM), combined with 50 mM NaCl in a nutrient solution. Photosynthesis progressively increased as the external K+ : Na+ ratios increased up to 0.75. The increase of photosynthesis and plant dry matter correlated positively with K+ : Na+ in xylem and leaves. The transport rates of K+ and Na+ from roots to xylem and leaves were inversely correlated. These ions presented an antagonistic pattern of accumulation in all organs. Maximum rates of photosynthesis and plant growth occurred with leaf K+ : Na+ ratios that ranged from 1.0 to 2.0, indicating that this parameter in leaves might be a good indicator for a favorable K+ homeostasis under salinity conditions. The higher K+ affinity and selectivity compared with Na+ in all organs associated with higher xylem flux and transport to shoots are essential for maintaining adequate K+ : Na+ ratios at the whole‐plant level. These characteristics, combined with adequate K+ concentrations, allow J. curcas to sustain high rates of photosynthesis and growth even under toxic NaCl levels.  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