全文获取类型
收费全文 | 98篇 |
免费 | 1篇 |
专业分类
林业 | 1篇 |
农学 | 3篇 |
5篇 | |
综合类 | 16篇 |
农作物 | 1篇 |
畜牧兽医 | 68篇 |
园艺 | 2篇 |
植物保护 | 3篇 |
出版年
2015年 | 1篇 |
2014年 | 2篇 |
2012年 | 3篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 6篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1950年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有99条查询结果,搜索用时 15 毫秒
1.
T.L. Blanchard DVM MS Dip ACT J.B. Jorgensen BS D.D. Varner DVM MS Dip ACT D.W. Forrest MS PhD J.W. Evans MS PhD 《Journal of Equine Veterinary Science》1996,16(5):195-201
To investigate effects of thermally-induced testicular degeneration on hormonal and seminal parameters in stallions, the scrotum was insulated for 36 hours in two mature (5-year-old mixed breed and 11-year-old Throughbred) stallions. Semen was collected daily for 10 days (DSO) prior to, and at intervals after, scrotal insulation. When DSO determinations were not being made, semen was collected 3 times weekly. Jugular blood samples were collected at 15-minute intervals for 6 hours from each stallion prior to, and at intervals after, scrotal insulation. A mouse interstitial cell testosterone assay was modified to quantify biologic activity of equine luteinizing hormone (BLH) in plasma samples. Immunoactive luteinizing hormone (ILH) and testosterone (T) concentrations were determined in plasma samples by routine RIA procedures. Percentages of progressively motile and morphologically normal spermatozoa began to decrease by 1 to 2 weeks postinsulation, reached nadir values at 3 to 3-1/2 weeks postinsulation, and returned to preinsulation values by 7 weeks postinsulation. Total number of spermatozoa and total number of progressively motile, morphologically normal spermatozoa in ejaculates at DSO returned to normal by 8 weeks postinsulation in stallion 2 and 12 weeks postinsulation in stallion 1. Concentrations of BLH and ILH increased, and while T concentrations decreased, immediately postinsulation. The increase in ILH concentrations was greater than the increase in BLH concentrations, resulting in a decrease in the BLH:ILH (B:I) ratio. Following the peak in LH secretion immediately postinsulation, LH concentrations gradually decreased while T concentrations increased. The B:I ratio was elevated from 1 to 13 weeks postinsulation compared to immediately postinsulation. In addition to changes in spermatozoal quality in ejaculates, stallion response to scrotal insulation included increased secretion of luteinizing hormone and impaired Leydig cell function (as determined by reduced testosterone concentration in circulating plasma). The proportion of biologically active LH secreted in response to thermal testicular injury increased during the recovery phase. 相似文献
2.
Antoine LF Gady Freddy WK Hermans Marion HBJ Van de Wal Eibertus N van Loo Richard GF Visser Christian WB Bachem 《Plant methods》2009,5(1):13-14
Background
The establishment of mutant populations together with the strategies for targeted mutation detection has been applied successfully to a large number of organisms including many species in the plant kingdom. Considerable efforts have been invested into research on tomato as a model for berry-fruit plants. With the progress of the tomato sequencing project, reverse genetics becomes an obvious and achievable goal. 相似文献3.
We studied the relationship of serum prolactin, estradiol-17 beta, and progesterone concentrations to plasma calcium, phosphorus, and free hydroxyproline concentrations, as well as to dry matter intake, in 14 aged dairy cows (mean of 4.5 parities), 7 of which became paretic, from 28 days before to 4 days after calving. Plasma calcium and phosphorus concentrations and dry matter intake decreased more at parturition in paretic cows than in nonparetic cows. Prolactin concentrations were not different between paretic and nonparetic cows, but were variable. Concentrations of estradiol were higher in paretic cows from 15 to 5 days before parturition, whereas hydroxyproline concentration was lower in paretic cows on days 10 through 3 before parturition. Progesterone concentration was lower in paretic cows and decreased earlier at parturition, compared with that in nonparetic cows. The findings suggested that high estradiol concentrations in late pregnancy inhibit bone resorption and predispose aged cows to parturient paresis. The earlier decrease in progesterone concentration at parturition and lower concentrations throughout late pregnancy might have contributed to the greater inappetence in paretic cows at parturition. The importance of prolactin in the pathogenesis of parturient paresis is not clear. 相似文献
4.
Urban dwellers experience conflicting thoughts and feelings about urban woodlands; valued for their natural qualities, the relief they provide from the stress of modern urban living and the opportunities they afford for children's play and exploration. At the same time the seclusion inherent in this type of urban greenspace seems fraught with risk from crime, vandalism and abuse. Whilst many of these characteristics are well-researched, less is known about the differing perceptions of particular social groups. This study aimed to explore the ways in which age affects urban dwellers’ aspirations, values and fears concerning the woods, and woodland accessibility, focusing on the views of elderly people (aged over 65). This pilot study was based in Norfolk Heritage Park, an urban park containing a variety of woodland settings located in Sheffield, UK. The questionnaire survey (participantsn=97) revealed that although walking is the most popular leisure activity, most respondents did not visit urban parks as often as they would like, regardless of age. Whilst many of the meanings associated with urban woodland (“relaxation”, “peacefulness”, “seasonal change”, “scenery” and “education”) were shared amongst age groups, it seemed that the elderly respondents particularly valued the woods for their links with the past, and opportunities for immersion in the natural world. Some respondents from all age groups had fears about their personal security in the woodland, and the concerns of the elderly were heightened by their perceived frailty, reduced mobility and sense of vulnerability; this age group had a corresponding need for particular measures to alleviate these problems. The study provides preliminary evidence for the idea that adults of different ages have differing perceptions and requirements in relation to urban woodlands. Due to the small sample size and other methodological issues, further research is needed to confirm and develop the findings. 相似文献
5.
6.
J B Jorgensen 《Acta veterinaria Scandinavica》1977,18(4):532-544
A porcine strain of Mycobacterium avium, Serotype 2, was used for intravenous inoculation of pigs in doses 5, 1, 10−1, 10−2 and 10−3 mg (1 mg = 78 × 106 viable units), 2 pigs per dose.Dose 5 mg proved fatal for both of the inoculated pigs, which were killed in extremis 64 and 69 days, respectively, after inoculation. Dose 1 mg caused clinical disease in 1 of 2 pigs, but was not lethal. Post mortem, the clinically affected pigs showed a generalized granulomatous tuberculosis. The other pig given 1 mg and the pigs given smaller doses, showed no clinical signs, and lesions and presence of acid-fasts were mostly limited to the lymph nodes of the lung, liver and digestive tract.All the pigs showed delayed hypersensitivity to avian PPD tuberculin (1000 t.u.) and some of them cross-reacted with human PPD tuberculin (1000 t.u.). The clinically affected pigs gave a very weak response to tuberculin, the others a strong response.The smallest dose capable of establishing an infection and producing tuberculous lesions was not determined, but seems to be less than 10−3 mg (78000 viable organisms). 相似文献
7.
S K Heimbecher K V Jorgensen R L Price 《Journal of the Association of Official Analytical Chemists》1988,71(2):285-287
Spray-dried skim milk, naturally contaminated with aflatoxin M1, was added to either raw or pasteurized whole milk to a final concentration of 1.1 microgram aflatoxin M1/L milk. Formalin (37% w/w) was added to the milk solutions to final concentrations of 0, 0.025, 0.05, and 0.1% formaldehyde. Samples were stored in the dark at 21 degrees C in plastic and glass containers and were analyzed for aflatoxin M1 at 0, 1, 2, 3, and 4 weeks. This experiment was repeated using only raw milk and glass containers. Aflatoxin M1 analyses were done at 0, 1, and 2 weeks. Aflatoxin M1 losses increased over time and with increased formaldehyde concentration. With both experiments, aflatoxin M1, levels after 2 weeks were less than 0.05 micrograms/L in samples containing 0.1% formaldehyde. 相似文献
8.
Jorgensen WL 《Science (New York, N.Y.)》2004,303(5665):1813-1818
An overview is given on the diverse uses of computational chemistry in drug discovery. Particular emphasis is placed on virtual screening, de novo design, evaluation of drug-likeness, and advanced methods for determining protein-ligand binding. 相似文献
9.
Jorgensen RA 《Science (New York, N.Y.)》2011,333(6046):1103-1104
10.
Alkaline hydrolyzates of RNA made in vivo by Escherichia coli contain ribonucleoside-3'-monophosphate-5'-triphosphates. These probably arise by hydrolysis of the initial nucleoside triphosphate from the 5' terminus of the nascent RNA chains. Logarithmically growing cultures, labeled for 45 seconds with (32)P-labeled phosphate, yield about 2000 molecules of labeled tetraphosphate per cell, this yield increasing only slightly with continued labeling. Only the tetraphosphates of adenosine and guanosine have been found in Escherichia coli, and these two are present in approximately equal amounts. 相似文献