全文获取类型
收费全文 | 599篇 |
免费 | 27篇 |
专业分类
林业 | 143篇 |
农学 | 15篇 |
118篇 | |
综合类 | 60篇 |
农作物 | 22篇 |
水产渔业 | 29篇 |
畜牧兽医 | 207篇 |
园艺 | 7篇 |
植物保护 | 25篇 |
出版年
2022年 | 6篇 |
2020年 | 11篇 |
2019年 | 9篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 23篇 |
2011年 | 39篇 |
2010年 | 13篇 |
2009年 | 18篇 |
2008年 | 39篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 21篇 |
2004年 | 20篇 |
2003年 | 26篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1977年 | 4篇 |
1975年 | 7篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1972年 | 8篇 |
1968年 | 4篇 |
1967年 | 6篇 |
1965年 | 4篇 |
1956年 | 4篇 |
1948年 | 7篇 |
1933年 | 5篇 |
1932年 | 12篇 |
1927年 | 7篇 |
1919年 | 6篇 |
1918年 | 5篇 |
1915年 | 4篇 |
1904年 | 5篇 |
1902年 | 3篇 |
排序方式: 共有626条查询结果,搜索用时 15 毫秒
141.
H W Soita J A Meier M Fehr P Yu D A Christensen J J McKinon A F Mustafa 《Archives of Animal Nutrition》2003,57(2):107-116
Twelve multiparous Holstein cows at 72 +/- 20 days in milk were used in a switch-back design with 14-d periods to determine the effect of replacing barley grain into a dairy total mixed ration with micronized or raw flaxseed on nutrient digestibility, milk yield, milk composition. Total mixed diets were (DM basis) 50% barley silage, 50% concentrate mix mainly rolled barley grain and canola meal. Diets were supplemented with 1 kg raw (RF) or micronized (MF) flaxseed to substitute 1 kg of rolled barley grain (C). Neutral detergent fibre, ADF and CP digestibility of the diets were not significantly affected by supplementation; however, calcium digestibility was reduced by 62% and 46% when raw and micronized flax were fed, respectively. Milk yield (38.3, 39.6, and 38.4 kg/d for diets C, RF and MF, respectively) was similar for all diets. Milk fat (3.50, 3.48, and 3.52%) and protein (3.31, 3.34, and 3.31%) for diets C, RF and MF, respectively, were not affected by treatment diets. Concentrations of c9, t11 conjugated linoleic acid (CLA; 0.51, 0.72 and 0.76 g/100 g fatty acids) in milk fat increased (P<0.05) similarly among the two flaxseed supplemented diets. The RF and MF diets significantly increased the C18:1, C18:1 trans-11, C18:2 cis-9, cis-12 and C18:3 in milk fat however, C12:0, C14:0 and C16:0 were significantly reduced compared with control. Replacing barley grain with flaxseed in the diet of lactating cows increased the beneficial fatty acids in milk without depressing nutrient digestibility. Micronization of flaxseed did not reveal any advantage over raw flaxseed. 相似文献
142.
Eberhard Mettenleiter Hans-Peter Meier Gottlieb Ueltschi Helmut Waibl 《Anatomia, histologia, embryologia》1992,21(3):246-255
The possibilities for imaging soft tissue structures, especially fluid-filled cavities such as articulations, bursae or tendon sheaths, have been improved markedly by sonography in recent years. Ultrasonic examinations were performed on the common tendon sheath of the musculus flexor hallucis longus and the musculus tibialis caudalis, from the medioplantar aspect of the tarsus, in 12 sound adult draft- and warm blood horses, and in 5 animals with a distended common sheath. The diagnostic precision of the sonographic examination of the tendon sheath is excellent and is superior to conventional radiography. A nuclear magnetic resonance tomogram of an isolated equine tarsus is presented for comparison method. 相似文献
143.
Valeria Meier Jürgen Besserer Malgorzata Roos Carla Rohrer Bley 《Veterinary and comparative oncology》2019,17(1):21-31
Previous trials showed the importance of administering radiation therapy (RT) with small doses per fraction in canine pelvic tumours to maintain acceptable toxicity levels. With increased accuracy/precision of RT, namely intensity‐modulated RT (IMRT), this approach might be challenged. Theoretical toxicity calculations for a new definitive‐intent moderately hypofractionated RT protocol for canine anal sac adenocarcinomas (ASAC) were performed, focussing on the risk of toxicity in pelvic organs at risk (OAR). Computed tomography datasets of 18 dogs with stage 3b ASAC were included. Re‐planning with margins for daily image‐guidance/IMRT was performed and a new protocol isoeffective to previously described definitive‐intent protocols was computed. Dose‐volume information were derived from individual plans and used for normal tissue complication probability (NTCP) computations. A 12 × 3.8 Gy protocol was computed for risk estimation. Tumour volumes ranged from 27.9 to 820.4 cm3 (mean 221.3 cm3 ± 188.9). For late rectal toxicity/bleeding ≥grade 2, median risk probability was 2.3% inter quartile range (IQR: 5.9; 95% confidence interval (CI): 1.2, 8.4) (rho = 0.436) and 3.4% (IQR: 0.96; 95%CI: 3.1, 4.0) (rho = 0.565), respectively. Median late toxicities in urinary bladder, kidneys and small bowel were <1%, except in one kidney. Myelopathy/myelonecrosis had a median risk probability of 4.1% (IQR: 23.5; 95%CI: 2.1, 25.2) (rho = 0.366) and 5.6% (IQR: 13.5; 95%CI: 3.1, 14.1) (rho = 0.363), respectively. However, graded risk showed a probability estimate for late spinal cord toxicity of ≥5% in 8/18 patients. The daily‐imaging IMRT 12 × 3.8 Gy protocol for canine ASAC seems tolerable for most cases, even in advanced disease. Theoretical dose computations serve as estimate, but are safe measures before implementing new protocols into clinical use. 相似文献
144.
Alan Akers Eberhard Ammermann Ernst Buschmann Norbert Gtz Walter Himmele Gisela Lorenz Ernst-Heinrich Pommer Costin Rentzea Franz Rhl Hardo Siegel Bernhard Zipperer Hubert Sauter Matthias Zipplies 《Pest management science》1991,31(4):521-538
In spite of considerable efforts by many workers, there has been a lack of progress in the area of amine fungicides since fenpropimorph. Random synthesis of a large variety of different amine compounds, as well as intelligent structural modification of the lead structure fenpropimorph (well over 15 000 amines have been screened at BASF alone) have not led to a new market product so far. Further work has been focused on the reported mode of action of fenpropimorph, notably on the inhibition of the sterol Δ14-reductase. Although some doubt has to be cast on the hypothesis that fenpropimorph behaves as a sterol mimic, the concept of ‘high energy intermediate’ inhibitors has been employed successfully. Rational drug design of azasterol mimics has led to a number of very potent inhibitors of the sterol Δ14-reductase which also displayed high fungicidal activity in the greenhouse. Although many of these compounds are more powerful reductase inhibitors than fenpropimorph, under field conditions none showed significant advantages over this established fungicide. Most likely, fenpropimorph already exhibits the maximum fungicidal activity which can be attained by blocking the sterol Δ14-reductase. This would mean that, with the development of the ‘second generation’ amine fungicide fenpropimorph, this class of compounds has already virtually been optimized. 相似文献
145.
HYPOFRACTIONATED RADIOTHERAPY FOR MACROSCOPIC CANINE SOFT TISSUE SARCOMA: A RETROSPECTIVE STUDY OF 50 CASES TREATED WITH A 5 × 6 GY PROTOCOL WITH OR WITHOUT METRONOMIC CHEMOTHERAPY 下载免费PDF全文
146.
Stummer P Fuchs-Baumgartinger A Franz S Nell B 《Veterinary journal (London, England : 1997)》2008,175(1):141-143
A 3-year old female goat with nephrotic syndrome was presented because of severe bilateral chemosis. The diagnosis was based on clinical findings, decreased packed cell volume, increased serum urea and creatinine, decreased serum protein and protein loss via the urinary tract. At post mortem examination, a chronic glomerulonephritis and interstitial nephritis were found. In addition to severe conjunctival oedema, ascites and subcutaneous oedema in the region of the larynx were noted. Immunohistochemistry for the detection of chlamydial antigen in the conjunctiva was negative. This is the first report of severe chemosis caused by nephrotic syndrome in a goat. 相似文献
147.
148.
Adrenal cortex reactivity in dairy cows differs between lactational stages and between different feeding levels 下载免费PDF全文
J. J. Gross R. S. Zbinden F. Dohme‐Meier R. M. Bruckmaier 《Journal of animal physiology and animal nutrition》2018,102(1):e309-e315
Changes in ACTH challenge test characteristics in dairy cows changing their physiological status at different lactational stages and different feeding levels were not investigated in terms of repeatability yet. In 23 multiparous Holstein cows (10 cows fed a sole fresh herbage diet without concentrate, 13 cows fed with concentrate), three ACTH challenge tests were performed: once during pregnancy shortly prior to drying off ( T1 ), and in week 3 ( T2 ) and 8 ( T3 ) after parturition. Test characteristics were correlated to performance and metabolic parameters: DMI, BW, energy balance (EB), plasma concentrations of free fatty acids (NEFA) and beta‐hydroxybutyrate (BHB). Basal plasma cortisol concentrations were higher at T1 compared with T2 and T3 (p < .05). The adrenal cortex sensitivity (expressed as total AUC (AUCt) of cortisol response after ACTH application) was lowest at T2 compared with T1 and T3 (p < .05). Ranking of the individual animals’ responses was not repeatable between time points of the ACTH tests. Enhancing the energy deficiency during early lactation by omission of concentrate did not affect baseline cortisol concentrations in plasma, but decreased peak height at T2 (p < .05). Baseline plasma cortisol concentrations were positively correlated with cortisol peak values after ACTH application, previous lactation performance, milk yield and BW (p < .05). The AUCt was positively correlated with baseline cortisol concentrations, EB and DMI. Cortisol release after ACTH injection was lower in animals with high plasma concentrations of NEFA, BHB and with higher contents of fat and free fatty acids in milk (p < .05). Cortisol peak height after ACTH administration was higher in cows with a more positive EB, higher DMI and lower plasma concentrations of NEFA and BHB. In summary, cortisol responses to ACTH challenges in this study were not repeatable in dairy cows changing their physiological status. 相似文献
149.
The influence of spaying and its timing relative to the onset of puberty on urinary and general behaviour in Labrador Retrievers 下载免费PDF全文
Orsolya Balogh Natalie Borruat Angela Andrea Meier Sonja Hartnack Iris M. Reichler 《Reproduction in domestic animals》2018,53(5):1184-1190
Benefits and risks of spaying on the behaviour of female dogs are controversially discussed. Increased aggressiveness and male urinary behaviour were postulated to be the consequence of masculinization after spaying in some female dogs. To investigate if spaying or its timing relative to the onset of puberty may have a masculinization effect, urinary behaviour, that is, frequency of urination, urinary posture and ground scratching after urination were recorded in 58 female Labrador Retrievers during 15 min of a daily walk with their owners. General behaviour of the dogs during the walks was assessed using an owner questionnaire. Data were analysed for age, reproductive status, lifetime of ovary exposure and/or time interval since spaying. Urinary behaviour of intact females (n = 12) and dogs spayed before (n = 17) or after (n = 29) puberty was similar and not influenced by age, lifetime of ovary exposure and/or time interval since spaying. Owners of spayed dogs described more frequent or more intense fear reaction in their animals in response to loud noises, unfamiliar objects approaching on or near the sidewalk, or if they were approached by unknown dogs barking, growling or jumping. In conclusion, we found no evidence of a masculinization effect after spaying on urinary behaviour in female Labrador Retrievers. In contrast to popular belief, gonadectomy did not inevitably result in a behaviourally more stable dog. Extrapolation of our findings from female Labrador Retrievers to other breeds should be performed with caution, as the effect of spaying on behaviour may differ among dog breeds. 相似文献
150.