全文获取类型
收费全文 | 306篇 |
免费 | 8篇 |
专业分类
林业 | 7篇 |
农学 | 28篇 |
12篇 | |
综合类 | 17篇 |
农作物 | 23篇 |
水产渔业 | 24篇 |
畜牧兽医 | 174篇 |
植物保护 | 29篇 |
出版年
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2003年 | 2篇 |
2002年 | 2篇 |
1999年 | 3篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 19篇 |
1989年 | 15篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1971年 | 3篇 |
1969年 | 2篇 |
1967年 | 2篇 |
1960年 | 3篇 |
1958年 | 4篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1955年 | 3篇 |
1954年 | 2篇 |
1946年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有314条查询结果,搜索用时 31 毫秒
81.
82.
83.
J.A. BACON R.G. ULRICH J.P. DAVIS E.M. THOMAS S.S. JOHNSON G.A. CONDER N.C. SANGSTER J.T. ROTHWELL R.O. MCCRACKEN B.H. LEE M.F. CLOTHIER T.G. GEARY & D.P. THOMPSON 《Journal of veterinary pharmacology and therapeutics》1998,21(3):190-198
PNU-87407 and PNU-88509, β-ketoamide anthelmintics that are structurally related to each other and to the salicylanilide anthelmintic closantel, exhibit different anthelmintic spectra and apparent toxicity in mammals. The basis for this differential pharmacology was examined in experiments that measured motility and adenosine triphosphate (ATP) levels in larval and adult stages of the gastrointestinal nematode, Haemonchus contortus , and in a vertebrate liver cell line and mitochondria. PNU-87407 and PNU-88509 both exhibited functional cross-resistance with closantel in larval migration assays using closantel-resistant and -sensitive isolates of H. contortus . Each compound reduced motility and ATP levels in cultured adult H. contortus in a concentration- and time-dependent manner; however, motility was reduced more rapidly by PNU-88509, and ATP levels were reduced by lower concentrations of closantel than the β-ketoamides. Tension recordings from segments of adult H. contortus showed that PNU-88509 induces spastic paralysis, while PNU-87407 and closantel induce flaccid paralysis of the somatic musculature. Marked differences in the actions of these compounds were also observed in the mammalian preparations. In Chang liver cells, ATP levels were reduced after 3 h exposures to 0.25 μ M PNU-87407, 1 μ M closantel or 10 μ M PNU-88509. Reductions in ATP caused by PNU-88509 were completely reversible, while the effects of closantel and PNU-87407 were irreversible. PNU-87407, closantel and PNU-88509 uncoupled oxidative phosphorylation in isolated rat liver mitochondria, inhibiting the respiratory control index (with glutamate or succinate as substrate) by 50% at concentrations of 0.14, 0.9 and 7.6 μ M , respectively. 相似文献
84.
The response of epidermal cells to attempted penetration by Erysiphe graminis was examined in the fifth leaf of 13 barley lines selected for partial resistance. In leaf segments fixed and stained 72 h after inoculation cell reactions were classified as susceptible or as exhibiting non-hypersensitive or hypersensitive resistance. The proportion of cells with each type of reaction varied in a continuous manner among the lines and there were significant differences between lines in the levels of non-hypersensitive and hypersensitive resistance. Crosses were made between lines exhibiting high and low levels of each resistance mechanism. Fifty challenged epidermal cells per duplicate leaf segment were examined on 45-50 F2 plants derived from two such crosses. The frequency distribution of each of the three types of cell reaction in the fifth leaf was found to be continuous and, in general, normally distributed and in no case was there a significant difference between parent and progeny mean values, suggesting that the two resistance mechanisms were under the control of several genes showing predominantly additive gene action. 相似文献
85.
Vitrification has been the method of choice for the cryopreservation of bovine oocytes, as rapid cooling decreases chilling sensitivity. The aim of this study was to determine the in vitro and in vivo survival and the viability of immature oocytes vitrified using super‐cooled liquid nitrogen. Immature oocytes were randomly allocated to three groups: (i) non‐vitrified control group, (ii) vitrified in normal (?196°C) liquid nitrogen (LN2) and (iii) vitrified in super‐cooled LN2 (≤?200°C). Open‐pulled glass micropipettes were used as vitrification containers. Immature oocytes were in vitro‐matured, fertilized and cultured to the blastocyst stage. In vitro viability was assessed by cleavage and blastocyst rates on days 2 and 7 of culture respectively. Vitrified blastocysts derived from the immature vitrified oocytes were directly transferred to synchronous recipients. The in vitro embryo development of vitrified immature oocytes was not influenced by the LN2 state. After direct transfer (one embryo per recipient) of 16 embryos obtained from immature vitrified oocytes (eight from each vitrified group), two healthy calves were born in each group. These results indicated that vitrification of immature bovine oocytes using glass micropipettes under normal or super‐cooled LN2, resulted in viable blastocysts and live calves following in vitro embryo production. 相似文献
86.
Hereditary cerebellar abiotrophy in Australian Kelpie dogs 总被引:1,自引:0,他引:1
87.
88.
JOSEPH HARARI MS dvm dipiomate acvs THOMAS E. BESSER dvm phd diplomate acvm SCOTT B. GUSTAFSON dvm ms dipiomate acvs KATRINA MEINKOTH dvm 《Veterinary surgery : VS》1993,22(1):27-30
Bacteria in blood cultures in 30 dogs undergoing high-speed dental scaling and tooth extraction were examined. One or more positive blood cultures were identified in 9 of 30 (30%) dogs. Pasteurella spp. were most frequently (5 dogs) isolated and were sensitive to ampicillin, penicillin, cephalothin, chloramphenicol, tetracycline, amoxicillin with clavulanic acid, and sul-famethoxazole with trimethoprim. Twg groups of 15 dogs each, anesthetized or sedated but not undergoing dental procedures, served as non-dentistry controls. There were no significant (p < .05) differences between the number of positive cultures in dentistry and non-dentistry groups. In healthy dogs undergoing high-speed dental scaling and tooth extraction, the occurrence of bacteria in blood cultures was much lower than previously reported. The clinical significance of positive blood cultures was uncertain. 相似文献
89.
90.
The development of powdery mildew on seven spring barley varieties lacking effective major resistance factors was compared in a small-plot field trial. Differences were observed at later growth stages indicating partial resistance in some varieties. Latent period and sporulation capacity were examined on the fifth or sixth leaf of these varieties plus several known to be susceptible, using plants raised under spore-free conditions. Latent period was extended in most partially resistant varieties compared with susceptible controls, more so at 5°C than at 10°C. Cumulative total spore production per colony over the 16-day sporulation period differed markedly between varieties, the most resistant yielding one-third as many spores as the susceptible controls. There was evidence that these resistance components were correlated with each other and with previous estimates of infection frequency. The significance of this finding, in relation to selection for improved levels of partial resistance, is discussed. 相似文献