全文获取类型
收费全文 | 358篇 |
免费 | 10篇 |
专业分类
林业 | 13篇 |
农学 | 10篇 |
基础科学 | 2篇 |
56篇 | |
综合类 | 91篇 |
农作物 | 16篇 |
水产渔业 | 26篇 |
畜牧兽医 | 100篇 |
园艺 | 4篇 |
植物保护 | 50篇 |
出版年
2022年 | 3篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 4篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 19篇 |
2012年 | 16篇 |
2011年 | 19篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 11篇 |
2007年 | 17篇 |
2006年 | 9篇 |
2005年 | 20篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 7篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 3篇 |
1950年 | 2篇 |
1946年 | 2篇 |
1913年 | 1篇 |
1903年 | 1篇 |
1889年 | 1篇 |
排序方式: 共有368条查询结果,搜索用时 281 毫秒
151.
152.
153.
Jeremy A. Baumgardt Michael L. Morrison Leonard A. Brennan Brian L. Pierce Tyler A. Campbell 《Strength and Conditioning Journal》2019,72(1):168-181
There is growing interest among resource managers in implementing long-term wildlife monitoring. The process to develop such a program may seem daunting, however, because it requires determining the species, metrics, sampling methods, experimental design, and level of effort necessary to achieve the desired power for detecting meaningful changes. Failure to give these decisions proper attention often leads to suboptimal information for decisions and planning objectives. Our primary objectives were to develop alternative scenarios for a monitoring program, including power estimates and sampling effort required to detect population changes for small mammals on rangelands in southern Texas. Our secondary objective was to present a framework for developing customized monitoring programs for tracking wildlife populations over time. We trapped small mammals using ~ 28 000 trap nights each year from 2014 to 2016 resulting in 13 183 captures of nine species. We estimated abundances and occupancy in each year for each species and conducted power analyses using simulations. We used these results to develop four multispecies monitoring scenarios: two with distinctly different levels of effort with abundance as the focal metric and two for monitoring occupancy. The most effort-intensive scenario required trapping 40 grids for 6 consecutive nights each yr. With this effort, we predicted it would be possible to detect annual changes in abundance of ≤ 10% after 10 yr for four species and net declines in occupancy of ≤ 50% after 10 yr for five species with a power of 0.90. The least effort-intensive scenario required trapping 30 transects for 4 consecutive nights each yr. We predicted this effort would allow for the detection of annual changes in occupancy rates between 35% and 55% after 10 yr for five species. Our study is an example for land managers, providing general guidelines for developing rigorous, long-term monitoring programs specific to their objectives. 相似文献
154.
Leonard A. C. Afouda Regina Kotchofa Razack Sare Valerien Zinsou Stephane Winter 《Phytoparasitica》2013,41(3):271-276
In surveys conducted in 2011 and 2012 to identify the viruses causing diseases on pepper and tomato in the department of Alibori in northern Benin, 451 samples of pepper and tomato were analyzed by ELISA using 11 specific antibodies. The highest virus incidence among the surveyed districts was recorded on pepper in Malanville (56.18%), followed by Karimama (39.32%). The most frequently found viruses were Pepper veinal mottle virus (PVMV), Cucumber mosaic virus (CMV), and Potato virus Y-necrotic (PVY-n), accounting respectively for 22.39%, 21.73% and 15.96% of the collected samples. Tomato yellow leaf curl virus (TYLCV) was detected in only 2.43% of the samples, whereas Alfalfa mosaic virus (AMV), Chilli veinal mottle virus (ChiVMV), Tomato mosaic virus (ToMV) and Tomato spotted wilt virus (TSWV) were not detected in any of the samples tested. Double and triple infections involving different virus combinations were found, respectively, in 14.86% and 4% of the samples. Five plant species (Euphorbia hirta Linnaeus, Moringa oleifera Lam, Leucas martinicencis (Jacquin) R. Brown, Combretum micranthum G. Don, Abelmoschus esculentus L. Moench.) out of 30 samples belonging to 13 botanical families, collected within or nearby tomato and pepper fields, were found infected with PVMV, PVY-n, and CMV. Control measures to reduce the impact of viruses on pepper and tomato production are discussed. This is the first report of viruses infecting pepper and tomato in Benin. 相似文献
155.
Catherine A. Loughin DVM Diplomate ACVS ACCT Leonard J. Marino MD FAAP 《Veterinary surgery : VS》2014,43(7):888-894
156.
Brian P. Grossbard DVM Catherine A. Loughin DVM Diplomate ACVS ACCT Leonard J. Marino MD FAAP Joseph Sackman Scott E. Umbaugh BSE MSEE PhD Patrick S. Solt BSEE MSCS Jakia Afruz BSAPECE MSAPECE Peter Leando PhD DSc DAc Martin L. Lesser PhD EMT‐CC Meredith Akerman MS 《Veterinary surgery : VS》2014,43(7):869-876
157.
Scott L McGee P Walsh C Fanning S Sweeney T Blanco J Karczmarczyk M Earley B Leonard N Sheridan JJ 《Veterinary microbiology》2009,134(3-4):288-293
Verotoxigenic E. coli (VTEC) belong to a diverse range of serotypes. Serotypes O157 and O26 are predominately identified in VTEC-associated disease in Europe, however due to difficulty in detection little is known about the epidemiology of non-O157 serotypes. This study reports the identification of 7 VTEC serotypes from cattle faeces and soil. Cattle faeces samples (n=128) were taken from animals in 6 different farms, with soil samples (n=20) obtained from 1 farm. After sample incubation in modified tryptone soy broth (mTSB) supplemented with streptomycin sulphate samples were plated onto sorbitol MacConkey (SMAC) also supplemented with streptomycin sulphate. Bacteria detected on the plates were subjected to biochemical testing, antibiotic resistance profiling, and PCR to detect typical virulence genes, beta-lactamase and class 1 integron associated genes. Serotyping was performed on isolates positive for virulence genes. E. coli was identified from 103 samples, with verotoxin genes present in 7 E. coli isolates. Of these 7 isolates, 5 were resistant to 5 or more antibiotics. The isolate resistant to 9 antimicrobials contained a class 1 integron structure. Serotyping identified 7 separate VTEC, O2:H27, O26:H11, O63:H(-), O148:H8, O149:H1, O174:H21 and ONT:H25. Six of these VTEC have been previously associated with human disease, however with the exception of O26:H11, these serotypes have been rarely reported worldwide. Increased surveillance is required to determine the prevalence of these and other non-O157 VTEC. The presence of multi-antibiotic resistance in these isolates is of concern, and the overall implications for public health must be ascertained. 相似文献
158.
Bolder SG Hendrickx H Sagis LM van der Linden E 《Journal of agricultural and food chemistry》2006,54(12):4229-4234
Fibril formation in mixtures of whey proteins upon heating at pH 2 was investigated. Fibrils were found to coexist with other structures, such as spherulites. These spherulites consist of radially oriented fibrils. At total protein concentrations above 6 wt %, transparent gels were formed. Changing the ratio between the various whey proteins did not affect this gelation concentration as long as beta-lactoglobulin (beta-lg) was present, suggesting that beta-lg was dominant in the gelation. Pure alpha-lactalbumin and pure bovine serum albumin did not form fibrils, nor did they gel upon heating at pH 2 and 80 degrees C for up to 10 h. They did however induce a decrease in the beta-lg concentration needed for gel formation upon heating at pH 2. Our results suggest that beta-lg is the only fibril forming protein at the conditions used and that no mixed fibrils are formed. 相似文献
159.
Many compounds derived from living organisms have found a use in crop protection. These compounds have formed the basis of chemical synthesis programmes to derive new chemical products; they have been used to identify new biochemical modes of action that can be exploited by industry-led discovery programmes; some have been used as starting materials for semi-synthetic derivatives; and many have been used or continue to be used directly as crop protection agents. This review examines only those compounds derived from living organisms that are currently used as pesticides. Plant growth regulators and semiochemicals have been excluded from the review, as have living organisms that exert their effects by the production of biologically active secondary metabolites. 相似文献
160.
Effect of stirring and seeding on whey protein fibril formation 总被引:3,自引:0,他引:3
Bolder SG Sagis LM Venema P van der Linden E 《Journal of agricultural and food chemistry》2007,55(14):5661-5669
The effect of stirring and seeding on the formation of fibrils in whey protein isolate (WPI) solutions was studied. More fibrils of a similar length are formed when WPI is stirred during heating at pH 2 and 80 degrees C compared to samples that were heated at rest. Addition of seeds did not show an additional effect compared to samples that were stirred. We propose a model for fibril formation, including an activation, nucleation, growth, and termination step. The activation and nucleation steps are the rate-determining steps. Fibril growth is relatively fast but terminates after prolonged heating. Two processes that possibly induce termination of fibril growth are hydrolysis of nonassembled monomers and inactivation of the growth ends of the fibrils. Stirring may break up immature fibrils, thus producing more active fibrils. Stirring also seems to accelerate the kinetics of fibril formation, resulting in an increase of the number of fibrils formed. 相似文献