全文获取类型
收费全文 | 254篇 |
免费 | 7篇 |
专业分类
林业 | 10篇 |
农学 | 6篇 |
基础科学 | 3篇 |
27篇 | |
综合类 | 34篇 |
农作物 | 35篇 |
水产渔业 | 16篇 |
畜牧兽医 | 117篇 |
园艺 | 2篇 |
植物保护 | 11篇 |
出版年
2023年 | 1篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 7篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 5篇 |
2008年 | 20篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 19篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 23篇 |
2001年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1964年 | 3篇 |
1961年 | 2篇 |
1945年 | 2篇 |
1944年 | 6篇 |
1943年 | 10篇 |
排序方式: 共有261条查询结果,搜索用时 187 毫秒
51.
Robert J. Brosnan Eugene P. Steffey Betsy Vaughan 《Research in veterinary science》2011,90(1):138-145
Digital perfusion pressure (DPP) equals mean arterial pressure (MAP) at the hoof coronet minus digital interstitial pressure (DIP) within the hoof. To test whether lamellar blood flow (LBF) changes proportionately to DPP, anesthesia was induced and maintained with isoflurane in six horses to target a MAP of 60 mmHg. Arterial, venous, and hoof interstitial pressures were measured in each pelvic limb. LBF was measured using fluorescent microspheres during dobutamine infusions targeting either 60 (low), 80 (medium), or 100 (high) mmHg MAP. Following euthanasia, hoof lamina was collected for microsphere isolation. To reduce intra-individual variability, medium and high pressures and flows were divided by their respective low pressure and flow baseline values, yielding indexed variables of ΔLBF and ΔDPP. The ΔLBF correlated negatively with the ΔDPP. We conclude that LBF was not solely determined by passive pressure-flow relationships and that systemic hypertension may not effectively increase dermal LBF in horses. 相似文献
52.
Prevalence of canine gastrointestinal helminths in urban Lusaka and rural Katete Districts of Zambia
Faecal samples were collected from January 2010 through September 2010 to determine the prevalence of gastrointestinal (GI) helminths infestation in dogs in urban Lusaka and rural Katete Districts of Zambia. A total of 452 faecal samples (n=160 Katete, n=292 Lusaka) were examined by faecal flotation for the presence of helminth eggs and 82.5% of dogs were positive for GI helminths in Katete compared to 76% for Lusaka. Positive results with the presence of at least one parasite corresponded to 72.9% Ancylostoma caninum, 11% Toxocara canis, 4.8% Toxascaris leonina, 2.4% Dipylidium caninum, 0.7% Taeniidae and 0.3% T. vulpis, species for Lusaka while Katete recorded 70.6% A. caninum, 18.1% T. vulpis, 11.1% T. canis, 13.1% D. caninum, 3.8% T. leonina, and 0.6% Taeniidae. Except for T. vulpis and D. caninum (p<0.05) the results indicated no significant difference in the prevalence of the identified GI helminth between Lusaka and Katete. There was no significant difference in the prevalence between genders of GI helminth infestation demonstrated in this study and only A. caninum showed significant difference in prevalence by age category. The study also showed the presence of zoonotic intestinal helminths A. caninum, T. canis and D. caninum. The study highlights that there was no significant difference in spectrum and prevalence of GI helminths between urban and rural areas in Zambia. It further brings to light the importance of educating owners of dogs on the importance of regular deworming of dogs and control of ectoparasites in order to minimise the risk that these dogs pose to them and the public. 相似文献
53.
Sack C Smoker M Chamkasem N Thompson R Satterfield G Masse C Mercer G Neuhaus B Cassias I Chang E Lin Y Macmahon S Wong J Zhang K Smith RE 《Journal of agricultural and food chemistry》2011,59(12):6383-6411
Seven FDA pesticide laboratories collaborated to develop and validate an LC-MS/MS method to determine 173 pesticides in <20 min. The average determination coefficient (r2) was >0.99 for all but two compounds tested. The limits of detection were <20 ng/mL for all compounds and <10 ng/mL for 363 of the 368 transitions reported. The method was used to determine pesticides in two AOAC sponsored proficiency samples. The LC-MS/MS determination was used for the analysis of oranges, carrots and spinach using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) method. Each matrix was fortified at 20, 100, 400, and 1000 ng/g. No false positive responses were detected in controls of the three matrices. 165 pesticides had recoveries between 70 and 130%, and 161 had minimum detection levels less than 10 ng/g. Recoveries of 169 compounds for the 1000 ng/g spikes were within 50-150%. A matrix effect study indicated all three matrices caused a small net suppressing effect, the most pronounced attributable to the citrus matrix. The procedure proved to be accurate, precise, linear, sensitive and rugged, and adds 100 pesticides to the scope of the FDA pesticide program. 相似文献
54.
Onyeike EN Omubo-Dede TT 《Plant foods for human nutrition (Dordrecht, Netherlands)》2002,57(3-4):223-231
The effects of heat treatments on the proximate composition, energy content, and levels of some antinutritional factors in brown and marble-colored African yam bean (AYB) seed flours were investigated. In raw brown and marble-colored AYB seed flours; moisture content, dry matter, crude protein, crude fat, ash, total carbohydrate and caloric value did not differ significantly at the 5% level. Autoclaving and cooking slightly increased the moisture level. Crude protein, crude fat, and ash contents were decreased by autoclaving and were further decreased by cooking. The decrease was not, however, considerable for the AYB that is not eaten raw and whose full nutritional potential as a legume can be derived only when heat treated, as previous reports have indicated for legume seeds.The levels of the toxicants were generally higher in the raw brown AYB compared to the marble-colored, and were generally reduced by both autoclaving and cooking. In the most commonly available and consumed marble-colored AYB, autoclaving at 121 °C, 15 psi for 20 min decreased cyanogenic glycosides by 46%, oxalate by 48.9%, tannin by 15.0%, saponin by 14.8% and trypsin inhibitors by 61.3% while cooking for 3.5 hours in tap water decreased these toxic factors by 66.5%, 70.3%, 72.2%, 48.7%, and 86.0%, respectively.The results indicate that for raw samples, varietal difference did not significantly affect nutrient composition though the toxicants were generally higher in the brown AYB than the marble-colored. Autoclaving decreased both nutrient value and the level of toxicants in the two seed types; values were further reduced by cooking. Of the toxicants, trypsin inhibitor was found to be the most heat-labile and of the heat treatment methods, cooking to tenderness is recommendable. 相似文献
55.
56.
Eugene A. Talley Thomas J. Fitzpatrick William L. Porter 《American Journal of Potato Research》1970,47(7):231-244
Free amino acid content, total nitrogen, extractable nitrogen, ratio of extractable to total nitrogen, solids content, and specific gravity in Cobbler, Katahdin, Kennebec, Red Pontiac, and Russet Burbank potatoes was studied. Each variety was grown in six different locations (Idaho, Maine, Pennsylvania, Wisconsin, Long Island, and the Red River Valley) during the years 1961 through 1963. The mean values for each factor, with significant differences indicated, are listed along with the high and low range, the coefficient of variation and the overall mean. The percent of total variance contributed by each of the variables and their interactions also are listed. Long Island potatoes had the highest nitrogen and amino acid content. Varietal differences were less significant. Proline was the most variable of the constituents measured. Aspartic and glutamic acids had the highest variability with respect to years grown. The effect of each variable varies from one constituent to another. 相似文献
57.
58.
59.
Gabriel Schiller Eugene D. Ungar Yehezkel Cohen 《Forest Ecology and Management》2002,170(1-3):117-126
Water use by vegetation is the most important parameter which is directly related to plant anatomical and eco-physiological characters, and to soil–bedrock water availability. This basic parameter is important in decision making, planning and management of the open areas under semiarid climatic conditions like those of Israel. Attempts were made to quantify the water use by Phillyrea latifolia L. by means of the heat pulse method. This method provides continuous monitoring of the convective heat pulse velocity (HPV) in the trunk xylem, thus facilitating the quantification of the transpiration flux per tree. The daily and annual water use by this species was estimated by extrapolations from the single-tree transpiration rates, based on the relationship between the leaf area of the measured trees and the entire area.
The lithological properties of the bedrock formations in each of the research sites caused significant differences between sites in the average daily transpiration rate and, hence, in the total water use by the P. latifolia scrub formation. The daily transpiration, averaged over a year, ranged between 4.00 and 8.15 l per day per tree, and the estimated annual water use ranged between 179.4 and 365.5 mm, i.e., between 30 and 61% of the annual rainfall in the winter preceding the measurements in 1993. 相似文献
60.
von Storch et al. (Reports, 22 October 2004, p. 679) criticized the ability of the "hockey stick" climate field reconstruction method to yield realistic estimates of past variation in Northern Hemisphere temperature. However, their conclusion was based on incorrect implementation of the reconstruction procedure. Calibration was performed using detrended data, thus artificially removing a large fraction of the physical response to radiative forcing. 相似文献