全文获取类型
收费全文 | 182篇 |
免费 | 20篇 |
国内免费 | 3篇 |
专业分类
林业 | 13篇 |
农学 | 13篇 |
基础科学 | 1篇 |
19篇 | |
综合类 | 13篇 |
农作物 | 8篇 |
水产渔业 | 9篇 |
畜牧兽医 | 109篇 |
园艺 | 5篇 |
植物保护 | 15篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 6篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 3篇 |
2009年 | 8篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 9篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有205条查询结果,搜索用时 31 毫秒
71.
72.
Climate and topography are two important controls on spatial patterns of fire disturbance in forests globally, via their influence
on fuel moisture and fuel production. To assess the influences of climate and topography on fire disturbance patterns in a
temperate forest region, we analyzed the mapped perimeters of fires that burned during 1930–2003 in two national parks in
the eastern United States. These were Great Smoky Mountains National Park (GSMNP) in the southern Appalachian Mountains and
Shenandoah National Park (SNP) in the central Appalachian Mountains. We conducted GIS analyses to assess trends in area burned
under differing climatic conditions and across topographic gradients (elevation, slope position, and aspect). We developed
a Classification and Regression Tree model in order to further explore the interactions between topography, climate, and fire.
The results demonstrate that climate is a strong driver of both spatial and temporal patterns of wildfire. Fire was most prevalent
in the drier SNP than the wetter GSMNP, and during drought years in both parks. Topography also influenced fire occurrence,
with relatively dry south-facing aspects, ridges, and lower elevations burning most frequently. However, the strength of topographic
trends varied according to the climatic context. Weaker topographic trends emerged in the drier SNP than GSMNP, and during
low-PDSI (dry) years than high-PDSI (wet) years in both parks. The apparent influence of climate on the spatial patterning
of fire suggests a more general concept, that disturbance-prone landscapes exhibit weaker fine-scale spatial patterning of
disturbance than do less disturbance-prone landscapes. 相似文献
73.
To assess the profitability of control schemes for Mycobacterium avium subspecies paratuberculosis (Map)-infection implemented in dairy herds, accurate estimates of its production effects are needed. This study aimed at quantifying the variation in milk yield of dairy cows according to their Map-infection status. The cow-status was determined by combining (i) its testing(s)-result(s) (serum ELISA, faecal culture (FC), PCR, Ziehl staining), (ii) the Map-status of its herd, and (iii) its possible vaccination against Map. A total of 15 490 cows in 569 herds located in western France was considered. The effect on test-day milk yield (TDMY) of the cow-status to Map was assessed separately in parity 1, 2 and 3 or more, using mixed linear models, after adjustment for herd-season (random), days in milk and breed. Average TDMY was significantly lower in cows from herds with at least one Map-infected cow (defined as positive herds). Individual TDMY showed a reduction ranging from 1.58 to 3.30, 2.03 to 2.51, 5.36 to 7.20 kg/day (P < 0.001) depending on parity for unvaccinated cows and testing ELISA-positive, PCR- or FC-positive, and Ziehl-positive, respectively, compared to cows in Map-free herds. The loss in milk yield increased with increased parity in ELISA-positive and Ziehl-positive cows. Cows that were both tested ELISA-positive and vaccinated had a smaller loss in TDMY than those that were unvaccinated. The estimates from this study can be used to further assess the economic impact associated with Map-infection in dairy herds or to help in the culling decisions regarding infected cows. 相似文献
74.
de Bruin T de Rooster H van Bree H Cox E 《American journal of veterinary research》2007,68(3):283-289
OBJECTIVE: To evaluate anticollagen type I antibodies in synovial fluid of the affected stifle joint, the contralateral stifle joint, and the left shoulder joint of dogs with unilateral cranial cruciate ligament (CrCL) rupture during an extended period of 12 to 18 months. ANIMALS: 13 client-owned dogs with CrCL rupture and 2 sham-operated dogs. PROCEDURES: All dogs were examined and arthrocentesis of all 3 joints was performed every 6 months after surgery. Synovial fluid samples were tested for anticollagen type I antibodies by use of an ELISA. RESULTS: Dogs with partial CrCL rupture had higher antibody titers than dogs with complete rupture. Six of 13 dogs ruptured the contralateral CrCL during the study, whereby higher antibody titers were found for the stifle joints than for the shoulder joint. Seronegative dogs or dogs with extremely low antibody titers and 2 dogs with high antibody titers did not sustain a CrCL rupture in the contralateral stifle joint. CONCLUSIONS AND CLINICAL RELEVANCE: In most dogs that had a CrCL rupture of the contralateral stifle joint, a distinct antibody titer gradient toward the stifle joints was detected, suggesting that there was a local inflammatory process in these joints. However, only a small number of sham-operated dogs were used to calculate the cutoff values used to determine the anticollagen type I antibody titers in these patients. Synovial fluid antibodies against collagen type I alone do not initiate CrCL rupture because not all dogs with high antibody titers sustained a CrCL rupture in the contralateral stifle joint. 相似文献
75.
Intra‐ and Interobserver Agreement on Radiographic Phenotype in the Diagnosis of Canine Hip Dysplasia
下载免费PDF全文
![点击此处可从《Veterinary surgery : VS》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ruth R. Fortrie DVM Geert Verhoeven DVM PhD Diplomate ECVS Bart Broeckx DVM Luc Duchateau MSc PhD Luc Janssens DVM PhD Diplomate ECVS Yves Samoy DVM PhD Elke Schreurs DVM Diplomate ECVDI Jimmy Saunders DVM PhD Diplomate ECVDI Henri van Bree DVM PhD Diplomate ECVS & ECVDI Peter Vandekerckhove DVM Diplomate ECVS Frank Coopman DVM PhD MSc 《Veterinary surgery : VS》2015,44(4):467-473
76.
77.
Fabiano T. P. K. T vora Anne C cile Meunier Aurore Vernet Murielle Portefaix Joë lle Milazzo Henri Adreit Didier Tharreau Oct vio L. Franco Angela Mehta 《水稻科学》2022,29(6):535-544
Rice genes OsDjA2 and OsERF104, encoding a chaperone protein and an APETELA2/ ethylene-responsive factor, respectively, are strongly induced in a compatible interaction with blast fungus, and also have function in plant susceptibility validated through gene silencing. Here, we reported the CRISPR/Cas9 knockout of OsDjA2 and OsERF104 genes resulting in considerable improvement of blast resistance. A total of 15 OsDjA2 (62.5%) and 17 OsERF104 (70.8%) T0 transformed lines were identified from 24 regenerated plants for each target and used in downstream experiments. Phenotyping of homozygous T1 mutant lines revealed not only a significant decrease in the number of blast lesions but also a reduction in the percentage of diseased leaf area, compared with the infected control plants. Our results supported CRISPR/Cas9-mediated target mutation in rice susceptibility genes as a potential and alternative breeding strategy for building resistance to blast disease. 相似文献
78.
稻瘟病菌株CH63和TH16杂交组合的遗传图谱构建及无毒基因定位 总被引:4,自引:0,他引:4
测定了CH63和TH16杂交后代(F1代子囊孢子群体)在36个水稻品种上的致病性,依据F1代子囊孢子群体在不同品种上的无毒性/毒性表型和SSR、SCAR和RAPD等分子标记的多态性位点共分离构建了稻瘟病菌的遗传图谱。图谱共有151个标记位点,7个连锁群,全长1038.4 cM。由杂交后代在不同品种上的无毒性/毒性分离鉴定出CH63菌株持有多个无毒基因,在该遗传图谱中初步定位了Avr2 K59、Avr C105TTP1、Avr Zh156、Avr Xuan1641、Avr Xuan6392和Avr C103TTP 6个无毒基因,分别定位在第1、第4和第7染色体上。 相似文献
79.
This work investigates whether Fourier transform infrared spectroscopy (FTIR), in combination with multivariate analysis, can distinguish extra virgin olive oils from different producing countries. Duplicate spectra were collected from 60 oils from four European countries. Two approaches to data analysis were used as follows: first, the "whole spectrum" method of partial least squares (PLS) followed by distance-based linear discriminant analysis (LDA) applied to the PLS scores, and second, a genetic algorithm (GA) for variate selection from the raw data, followed by LDA applied to the selected subset. The PLS-LDA approach produced a cross-validation success rate of 96%, whereas the GA-LDA approach achieved a 100% cross-validation success rate, from subsets comprising only eight variates. Neither the selected variate nor the whole spectrum approach was able to offer insight into the origin of the discrimination in biochemical terms. However, FTIR analysis is rapid, and this work shows that it has the required discriminatory power to potentially offer a "black box" method of screening oils to verify their country of origin. 相似文献
80.
Yusuf Sen Zhu Feng Henri Vandenbroucke Jan van der Wolf Richard G. F. Visser A. W. van Heusden 《Euphytica》2013,190(2):309-317
Bacterial canker of tomato, caused by Clavibacter michiganensis subsp. michiganensis (Cmm), is considered the most serious bacterial threat, resulting in high damages in production areas. Worldwide, Cmm is subjected to quarantine regulations.There is no cultivar in market containing Cmm resistance genes. This project aimed to screen tomatoes or wild relatives of tomato for resistance to Cmm, to be used for starting breeding programs. We have screened 24 different wild accessions of tomato and found several new tolerant sources: Solanum pimpinellifolium GI.1554, S. parviflorum LA735 and S. parviflorum LA2072. We also confirmed the tolerance which was reported previously in S. peruvianum LA2157, S. peruvianum PI127829, S. peruvianum LA385, S. habrochaites LA407 and S. lycopersicum cv. IRAT L3. No immunity was found. Also accessions showing a low disease score still contained high titers of bacteria as determined by a dilution plating method, using tow selective media. These results were confirmed with a TaqMan real time PCR assay, which was developed to determine and quantify Cmm in planta. 相似文献