全文获取类型
收费全文 | 266篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
林业 | 5篇 |
农学 | 28篇 |
12篇 | |
综合类 | 10篇 |
农作物 | 23篇 |
水产渔业 | 27篇 |
畜牧兽医 | 134篇 |
植物保护 | 29篇 |
出版年
2017年 | 2篇 |
2015年 | 3篇 |
2012年 | 2篇 |
2011年 | 8篇 |
2010年 | 6篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 3篇 |
2003年 | 2篇 |
1998年 | 5篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 16篇 |
1989年 | 8篇 |
1988年 | 11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 |
1966年 | 1篇 |
1963年 | 1篇 |
1960年 | 3篇 |
1959年 | 1篇 |
1958年 | 4篇 |
1957年 | 2篇 |
1956年 | 2篇 |
1955年 | 3篇 |
1954年 | 2篇 |
1953年 | 1篇 |
1946年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 15 毫秒
1.
WILLIAM B. THOMAS DVM DONALD C. SORJONEN DVM MS Diplomate ACVIM STEPHEN T. SIMPSON DVM MS Diplomate ACVIM 《Veterinary surgery : VS》1991,20(6):409-412
Twenty-eight surgical procedures were performed in 23 dogs with atlantoaxial subluxation. Dorsal stabilization in seven dogs resulted in two recoveries and five failures of fixation. Ventral decompression and stabilization in 18 dogs resulted in eight recoveries and four failures of fixation. Six dogs died or were euthanatized within 7 days of ventral stabilization. Using either technique, four of seven nonambulatory dogs recovered. 相似文献
2.
Résumé. Des plantules de mais sont cultivées à partir de la graine, à 1'obscurite ct i la lumiere, sur des solutions tamponnées (pH5,8) d'hydrazidemalfrque (HM) de concentrations allant de 10' a 10−3 M. AUX faibles concentrations (10° et 10−6 M), I'HM stimule la croissance et la formation des racines; aux autres concentrations, it est inhibiteur. L'inhibition de croissance provoquee par I'HM est accompagnee d'une augmentation de poids sec et de la teneur en anthocyanes.
L'HM n'influence pas in vitro la destruction de I'auxine par des extraits de mais, mais les extraits de plantes traitees par cette substance degradent l'hormone moins rapidement; parallelement, l'activite catalasique est diminuee mais l'activite péroxydasique est augmented. Le mode d'action de I'HM sur la croissanee et la rhizogenpse, compart à celui de la lumierc, est discute en rapport avec ses effets sur le raetabolisme auxinique. 相似文献
L'HM n'influence pas in vitro la destruction de I'auxine par des extraits de mais, mais les extraits de plantes traitees par cette substance degradent l'hormone moins rapidement; parallelement, l'activite catalasique est diminuee mais l'activite péroxydasique est augmented. Le mode d'action de I'HM sur la croissanee et la rhizogenpse, compart à celui de la lumierc, est discute en rapport avec ses effets sur le raetabolisme auxinique. 相似文献
3.
THOMAS I. OFUYA 《Integrated Pest Management Reviews》1997,2(4):199-207
Cowpea, Vigna unguiculata (L.) Walpers, is a major dietary staple in tropical Africa where it is most often cultivated. The production is, however, greatly hampered by severe infestation and damage by insect pests including the cowpea aphid, Aphis craccivora Koch. The damage and bionomics of the aphid are briefly introduced. Chemical, cultural, physical and biological methods, and use of plant resistance for A. craccivora control in cowpea are reviewed. Finally, prospects for integrated pest management are discussed 相似文献
4.
Experiments were conducted to examine the processes leading up to the infection of Lolium temulentum by crown rust ( Puccinia coronata ), stem rust ( P. graminis ) and brown rust ( P. loliina ), and the effects of temperature on these processes and sporulation. Uredia of all three rusts were produced freely if the adaxial leaf surface was inoculated, but did not form following inoculation of the abaxial surface. Light and scanning electron microscopy revealed abnormal growth of germlings on the abaxial surface which had amorphous sheet-like epicuticular waxes and very few stomata. On the adaxial leaf surface germ tubes of all the rusts orientated at right angles to the long axis of the leaf. However, the directional growth of germ tubes was often disrupted when they contacted the surface of bulliform cells at the base of leaf grooves. For P. loliina the optimum temperatures for urediospore germination and sub-stomatal vesicle formation were 12–16°C, and 8–20°C for appressorium formation. The optimum temperatures, for the same stages of fungal development, for P. coronata and P. graminis were higher. Urediospore production of P. loliina was higher at 10°C than at 25°C, but was similar at both temperatures for P. coronata . 相似文献
5.
The paper analyzes the hypothesis that the distribution of dominant plant species and characteristics of plant communities are related to groundwater depth. The results showed that variations of groundwater depth impacted distributions and characteristics of dominant plant communities. However, besides groundwater depth, the community composition and species diversity were also influenced by physiognomy of the habitat. Based on the similarity coefficient, the differences between dominant plant communities were significant at different groundwater depths. Compared with other results relating to desert vegetation and groundwater depth, variations of community distribution were similar at the large spatial scale. However, in this extremely arid region, there were significant differences in community type and community succession when compared with other arid regions, especially in relationship to deep groundwater depth. With groundwater depth from deep to shallow, communities transformed with the sequence of Alhagi communities, Tamarix spp. communities, Populus communities, Phragmites communities, and Sophora communities. At groundwater depth of less than 6.0 m, the community type and composition changed, and the species diversity increased. Among these dominant species, Tamarix exhibited the biggest efficiency in resource utilization according to niche breadth, which means it possessed the best adaptability to environmental conditions at the oasis margins. 相似文献
6.
A series of trials was conducted to compare the digestibility of organic matter in castrated male sheep and non-lactating and lactating cows given diets containing lucerne cobs. Similar digestibility coefficients were determined when sheep and non-lactating cows were given hay and lucerne cobs, but lactating cows digested diets of hay, lucerne cobs and concentrates less well than sheep. It is concluded that if sheep are used in digestibility trials with diets containing processed lucerne and concentrates intended for milking cows, appreciable errors of prediction of digestibility of organic matter may arise. 相似文献
7.
P. E. L. THOMAS 《Weed Research》1969,9(1):1-8
Summary. The effects of all combinations of five desiccation treatments, two temperatures and three durations of desiccation on the survival of Cyperus esculentus tubers and two-node Cynodon dactylon rhizome fragments were examined in laboratory and glasshouse experiments.
Cyperus esculentus tuber survival was greater at 22°C than at 4°C. Duration of desiccation did not influence tuber survival, except at the lower temperature.
Survival of Cynodon dactylon rhizome fragments was greatly influenced by desiccation treatment, duration of desiccation and the interaction of these two factors. No buds survived when rhizomes reached 50% of their original weight, indicating good tolerance of desiccation since the original dry-matter content of rhizomes in this experiment was 41·2%. 相似文献
Cyperus esculentus tuber survival was greater at 22°C than at 4°C. Duration of desiccation did not influence tuber survival, except at the lower temperature.
Survival of Cynodon dactylon rhizome fragments was greatly influenced by desiccation treatment, duration of desiccation and the interaction of these two factors. No buds survived when rhizomes reached 50% of their original weight, indicating good tolerance of desiccation since the original dry-matter content of rhizomes in this experiment was 41·2%. 相似文献
8.
This paper describes some recent experimental and theoreticalwork on the growth and spread of fire in the open and discussessome examples of field data in terms of the theoretical calculationspresented. The lengths of flames from laboratory fires have been relatedto the size and rate of burning of the fuel by formulae derivedfrom a simplified dimensional analysis. The effects of a windblowing across a long fuel bed on the length and orientationof flames are also described. The scaling laws for flame heightsuggest that in the horizontal spread of fire, heat transferfrom the flames above the fuel bed is important primarily withshallow fuel beds. It is suggested that the main effect of a wind on crib firesis aerodynamic. The wind deflects the advancing fire front fromthe vertical, but perpendicular to this deflected front therate of spread of fire, at least for cribs, is roughly the sameas in still air. However, a theory of spread allowing for heattransfer through the fuel bed and radiation from the flamespredicts that there can be a stable fast spreadas well as a slow spread. In fastspread the flames are thick and control the spread. In slow spread radiant heat transfer from theburning zone is usually responsible for the spread. The flamesare thin and of low emissivity. The most important factors determiningthe rate of slow spread R are pb the bulk densityof the fuel bed and ø the deflection from the verticalof the front of burning fuel which varies with wind speed. Rpb cos ø is approximately constant over a wide rangeof conditions with an order of magnitude of 510 mg cm2s1. 相似文献
9.
10.