全文获取类型
收费全文 | 273篇 |
免费 | 16篇 |
专业分类
林业 | 24篇 |
农学 | 4篇 |
基础科学 | 2篇 |
57篇 | |
综合类 | 44篇 |
农作物 | 11篇 |
水产渔业 | 23篇 |
畜牧兽医 | 81篇 |
园艺 | 8篇 |
植物保护 | 35篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 17篇 |
2011年 | 26篇 |
2010年 | 13篇 |
2009年 | 14篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 18篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
1944年 | 1篇 |
1941年 | 1篇 |
排序方式: 共有289条查询结果,搜索用时 15 毫秒
61.
P. David Jones Laurence R. Schimleck Richard F. Daniels Alexander Clark III Robert C. Purnell 《Wood Science and Technology》2008,42(5):385-400
A necessary objective for tree-breeding programs, with a focus on wood quality, is the measurement of wood properties on a
whole-tree basis, however, the time and cost involved limits the numbers of trees sampled. Near infrared (NIR) spectroscopy
provides an alternative and recently, it has been demonstrated that calibrations based on milled increment cores and whole-tree
data can provide good estimates of whole-tree properties. Several options exist for sampling standing trees and the aim of
this study was to compare wood property calibrations based on NIR spectra collected from samples obtained using different
sampling methods. Calibrations for whole-tree lignin and basic specific gravity based on NIR spectra from whole-tree chips
(milled or intact) had the strongest statistics, calibrations based on NIR spectra from milled increment cores were similar.
Other options for sampling the tree (drill shavings, etc.) gave errors that were too large for practical applications. If
an increment core is going to be used to estimate whole-tree properties, it is recommended that it be dried and milled prior
to analysis. 相似文献
62.
Paul C. Cleland F. Chris Baldock Pornchai Chamnanpood Laurence J. Gleeson 《Preventive veterinary medicine》1996,26(3-4):253-261
A study was undertaken in northern Thailand to identify factors which put some villages at higher risk of foot-and-mouth disease (FMD) outbreaks than others. The number of FMD outbreaks experienced in the previous 5 years and data on 145 putative risk factors were obtained by interview from 60 villages during 1991–1992. Univariable analyses identified 27 factors for further investigation using logistic regression. When villages were classified into three FMD frequency groups of zero to one, two to three or four or more outbreaks in the last 5 years, the important factors explaining the differences in risk were the total number of cattle and buffaloes purchased in the previous year, the number of neighbouring villages which shared a common water source and whether agriculture was the most important source of cash income for the village. These factors were also the most important variables in explaining the difference in risk when comparing villages with zero or one outbreak with those having four or more. We concluded that the greatest impact on reducing spread of FMD among villages would be obtained through the development of strategies to reduce the likelihood of introduction through livestock purchases and for villagers to take greater care when livestock are grazed with those from neighbouring villages and when sharing common water supplies. 相似文献
63.
Valentin Janvier Laurence Evrard Simona Cerri Alexandra Gougnard Valeria Busoni 《Veterinary radiology & ultrasound》2016,57(1):65-74
Ultrasonography and radiography are commonly used for staging of lymphoma in horses, however there is little published information on imaging characteristics for horses with confirmed disease. The purpose of this retrospective, case series study was to describe ultrasonographic and radiographic findings for a group of horses with a confirmed diagnosis of lymphoma. A total of 13 horses were sampled. Lymphadenopathy (8/13), peritoneal effusion (6/13), splenic (6/13), and hepatic (5/13) lesions were the most frequently identified. The predominant splenic and hepatic ultrasonographic lesions were hypoechoic nodules, organomegaly, and changes in echogenicity. Digestive tract lesions were detected in three horses and these included focal thickening and decreased echogenicity of the small (2/13) and large intestinal (2/13) wall. Thoracic lesions were predominantly pleural effusion (4/13), lymphadenopathy (4/13), and lung parenchymal changes (3/13). Enlarged lymph nodes were detected radiographically (4/13) and/or ultrasonographically (2/13) in the thorax and ultrasonographically in the abdomen (7/13) and in the caudal cervical region (4/13). Findings supported the use of abdominal and thoracic ultrasonography for lymphoma staging in horses. Ultrasound landmarks for localizing cecal and caudal deep cervical lymph nodes were also provided. 相似文献
64.
Detection and seroprevalence of morbillivirus and other paramyxoviruses in geriatric cats with and without evidence of azotemic chronic kidney disease 下载免费PDF全文
65.
66.
Brice Marolleau Aurélien Petiteau Marie-Noëlle Bellanger Mélanie Sannier Nadège Le Pocreau Laetitia Porcher Sophie Paillard Fabrice Foucher Tatiana Thouroude Laurana Serres-Giardi Gabriela Aguileta Annie Chastellier Caroline Bonneau Bruno Le Cam Vanessa Soufflet-Freslon Laurence Hibrand-Saint Oyant 《Plant pathology》2020,69(6):1093-1107
The haploid ascomycete Diplocarpon rosae is the causal agent of black spot disease on roses, a widespread and devastating disease in the outdoor landscape. In this study, we established a Eurasian collection of 77 monoconidial strains of D. rosae: 50 strains collected on cultivated roses in Europe and Asia, and 27 strains on wild roses in Kazakhstan. To provide tools to describe its biology and to study its genetic diversity, we sequenced two strains of D. rosae using Illumina paired-end technology. The genome sizes of these two strains were estimated at 31.1 and 35.2 Mb, which are two times smaller than the genome size of the unique strain previously published. A BUSCO analysis confirmed a genome duplication of the strain previously sequenced and partial gene duplication of strains analysed in this study. Using the two genome sequences, 27 polymorphic microsatellite markers were identified. Polymorphism analysis of the 77 strains revealed a strong genetic differentiation between strains from cultivated and wild roses, and a lower diversity within the fungal population from cultivated roses compared to the population from wild roses. Pathogenicity of 10 strains was evaluated on 9 rose cultivars inoculated in the greenhouse. Disease scoring allowed the classification of strains into three groups and the characterization of resistance of rose cultivars. Good correlation observed between resistance scoring in greenhouse conditions and in the field indicates that pathogenicity assays in controlled conditions could be very useful in the near future to rapidly characterize the resistance of new rose varieties to black spot disease. 相似文献
67.
Sara Torfs DVM Tamara Levet DVM Catherine Delesalle DVM PhD Jeroen Dewulf DVM Diplomate ECVPH Lieven Vlaminck DVM PhD Diplomate ECVS Frederik Pille DVM PhD Diplomate ECVS Laurence Lefere DVM Ann Martens DVM PhD Diplomate ECVS 《Veterinary surgery : VS》2010,39(5):616-620
Objective: To assess risk factors for celiotomy incisional infection in horses, especially the use of staples for skin closure. Study Design: Case series. Animals: Horses (n=356) that had 1 exploratory celiotomy for colic and survived >2 weeks after surgery between March 1, 2004 and December 31, 2007. Methods: Incisions were classified as “normal” (no complication, only edema, serous drainage lasting <24 hours) or as “surgical site infection (SSI)” (persistent serosanguinous drainage or purulent drainage with or without positive bacterial culture). All possible risk factors, including method of skin closure (monofilament sutures or staples), were statistically analyzed using univariate and multivariate logistic regression. Results: Of 356 horses, 303 (85%) had normal wound healing and 53 (15%) developed a SSI (purulent: 48 [14%]; persistent serosanguinous: 5 [1%]). Bacterial cultures were positive in 33 of 40 cases. Factors significantly associated with SSI in the multivariate analysis were: use of staples for skin closure (odds ratio [OR] 3.85, P<.001) and surgical site closure by a 1st or 2nd year resident (OR 2.20, P=.016). Lavage of the linea alba with sterile saline solution after closure was a protective factor (OR 0.38, P=.004). Conclusion: Use of staples for skin closure and less experienced surgeons closing the abdomen are risk factors for incisional infection. Incisional lavage after linea alba closure was a protective factor. Clinical Relevance: Despite their ease and speed of application, skin staples can lead to an increase in celiotomy wound complications in horses. 相似文献
68.
Totté P Rodrigues V Yaya A Hamadou B Cisse O Diallo M Niang M Thiaucourt F Dedieu L 《Veterinary research》2008,39(1):8
A better understanding of protective immune memory against contagious bovine pleuropneumonia (CBPP) is needed in order to facilitate the development of safer vaccines based on selected components of the pathogen. For this purpose, cells collected from lymph nodes draining the lungs of Mycoplasma mycoides subsp. mycoides small colony biotype (MmmSC)-infected cattle were stimulated with the pathogen in vitro and evaluated concurrently for proliferation (CFSE based method), expression of activation, memory markers and cytokine production. Direct evidence is presented for a major contribution of CD4+ T cells to the vigorous proliferative and T1 biased cytokine recall responses observed in cattle that have recovered from infection but not in animals developing the acute form of the disease. Two different phenotypes of MmmSC-specific memory CD4 were observed based on CD62L expression and proliferative capacities. Furthermore, recall proliferation of B cells also occurred but was strictly dependent on the presence of CD4. The information provided in this study will facilitate the search for MmmSC antigens that have potential for the development of subunit vaccines against CBPP. 相似文献
69.
Nondestructive estimation of wood chemical composition of sections of radial wood strips by diffuse reflectance near infrared spectroscopy 总被引:2,自引:1,他引:2
P. David Jones Laurence R. Schimleck Gary F. Peter Richard F. Daniels Alexander Clark III 《Wood Science and Technology》2006,40(8):709-720
The use of calibrated near infrared (NIR) spectroscopy for predicting the chemical composition of Pinus taeda L. (loblolly pine) wood samples is investigated. Seventeen P. taeda radial strips, representing seven different sites were selected and NIR spectra were obtained from the radial longitudinal face of each strip. The spectra were obtained in 12.5 mm sections from pre-determined positions that represented juvenile wood (close to pith), transition wood (zone between juvenile and mature wood), and mature wood (close to bark). For these sections, cellulose, hemicellulose, lignin (acid soluble and insoluble), arabinan, galactan, glucan, mannan, and xylan contents were determined by standard analytical chemistry methods. Calibrations were developed for each chemical constituent using the NIR spectra, wood chemistry data and partial least squares (PLS) regression. Relationships were variable with the best results being obtained for cellulose, glucan, xylan, mannan, and lignin. Prediction errors were high and may be a consequence of the diverse origins of the samples in the test set. Further research with a larger number of samples is required to determine if prediction errors can be reduced. 相似文献
70.
Marine Fish Larvae Feeding: Formulated Diets or Live Prey? 总被引:7,自引:0,他引:7
Jeannine People Le Ruyet Jean Claude Alexandre Laurence Thébaud Chantal Mugnier 《Journal of the World Aquaculture Society》1993,24(2):211-224
In the rearing of larval marine fish, any diet that reduces dependance on live prey production is of technical and economic interest. Weaning juveniles with a completely developed digestive tract to a conventional diet, (i.e., "late weaning") can be successful in any marine fish species. For example, weaning one-month-old sea bass (20 mg) to the study's reference diet, Sevbar, resulted in over 85% survival (40% from hatching) and 1.25 g fish at day 90 (at 19 C)
In contrast, "early weaning" of larvae to special microdiets during the first month is still difficult. The best way to reduce live prey utilization in sea bass is to wean larvae at about 3–4 mg in size (day 20). If weaning could be accomplished 15 days earlier, Artemia savings could be as high as 80%. However, this introduces risks relative to growth retardation (30% weight loss) and lower juvenile quality, including greater size variability and skeletal abnormalities. Similar results have been obtained with commercial microparticles (Fry Feed Kyowa) and experimental microbound diets (MBD) made from raw materials (alginate MBD) or preferably from freeze-dried protein sources (zein MBD).
Total replacement of live prey is still impossible in marine fish. Sea bass larvae fed formulated diets exclusively from first feeding (0.3 mg larval wet weight), or even from their second week of life onwards, exhibited low survival and poor growth. Better results can be obtained when formulated diets are used in combination with live prey from first feeding, although the optimal ratio of live prey to formulated diet is still to be specified. 相似文献
In contrast, "early weaning" of larvae to special microdiets during the first month is still difficult. The best way to reduce live prey utilization in sea bass is to wean larvae at about 3–4 mg in size (day 20). If weaning could be accomplished 15 days earlier, Artemia savings could be as high as 80%. However, this introduces risks relative to growth retardation (30% weight loss) and lower juvenile quality, including greater size variability and skeletal abnormalities. Similar results have been obtained with commercial microparticles (Fry Feed Kyowa) and experimental microbound diets (MBD) made from raw materials (alginate MBD) or preferably from freeze-dried protein sources (zein MBD).
Total replacement of live prey is still impossible in marine fish. Sea bass larvae fed formulated diets exclusively from first feeding (0.3 mg larval wet weight), or even from their second week of life onwards, exhibited low survival and poor growth. Better results can be obtained when formulated diets are used in combination with live prey from first feeding, although the optimal ratio of live prey to formulated diet is still to be specified. 相似文献