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61.
JAYNE E. ELLIS MICHAEL A. WYDER LINDA ZHOU ARUN GUPTA HARRY RUDNEY EDNA S. KANESHIRO 《The Journal of eukaryotic microbiology》1996,43(3):165-170
The lipids of purified preparations of Pneumocystis carinii carinii freshly isolated from infected rats were analyzed and compared with those of whole lungs from normal and methylprednisolone-immunosuppressed uninfected rats. In this study, the neutral lipid fraction was examined in detail; the relative concentrations of individual classes making up this fraction were quantified. Of particular interest was the nature of the organism's ubiquinone (coenzyme Q, CoQ) fraction because atovaquone, a hydroxynaphtho-quinone (566C80) analog of ubiquinone, is efficacious in the treatment of P. carinii pneumonia. The ubiquinone concentration in both P. carinii and lung tissues was relatively low compared to that present in rat heart and liver tissues. Two homologs were identified in the organism: CoQ10 was the predominant homolog with lesser amounts of CoQ9 present. In contrast, the lungs of normal and immunosuppressed uninfected rats had CoQ9 and lesser amounts of CoQ8 , but no detectable CoQ10 . Furthermore, radiolabeled mevalonic acid was incorporated in vitro into the ubiquinone fraction of P. carinii indicating that the organism has the de novo branch of the isoprenoid biosynthetic pathway leading to polyprenyl formation. Hence, it was concluded that CoQ10 (if not both CoQ110 and CoQ9 ) in P. carinii as not scavenged from the host but was synthesized by the organism. Although lung tissues contained substantial free fatty acids, the organism was enriched in these lipids. The high concentration of free fatty acids and relatively low level of triglycerides in P. carinii suggest that fatty acids may represent major carbon sources for ATP production by the organism. 相似文献
62.
Field experiments comparing six spraying programmes and two fungicides for control of coffee berry disease were carried out at three sites during 1968. These established that protection of the crop by sprays applied throughout the long rains (February–July) gave the best control and increased yields threefold. Early season spray programmes, which reduced the sporulating capacity of the pathogen in coffee twigs, but which ceased before the end of the rainy season, gave no disease control in the late crop (harvested October-December) and yields were less than in unsprayed controls. All programmes which gave protection at the onset of the rains gave some disease control in the early crop (harvested June-August). Captafol (‘Ortho-Difolatan’ 80 WP) was better than a 50% copper formulation (‘Perenox’). Conditions suitable for infection, as determined from meteorological records, occurred frequently during both rainy seasons. Estimates of sporulating capacity and data from spore trappings showed that although inoculum from the bark might initiate an epidemic, subsequent disease progress was more dependent upon spores derived from diseased berries; these accounted for most of the inoculum dispersed during the greater part of the season. Removal of the early crop, which was very small, had no detectable effect on disease in the late crop. Although losses were greatest with early season spray programmes, these did nevertheless delay the onset of the epidemic. However, the subsequent rate of disease increase was greatest and ‘scab’ lesion formation least in these treatments. ‘Scab’ lesions were most abundant in those treatments which caused least delay; in unsprayed coffee, it appeared that early exposure to infection resulted in ‘scab’ lesion formation which subsequently retarded the rate of disease progress. Tree height was positively correlated with disease incidence, but there was little effect of tree aspect. Crop density had a small effect on disease incidence within branches. 相似文献
63.
The relationship between seed moisture content and seed longevityin sesame (Sesamum indicum L.) in hermetic storage at 50 °Cis logarithmic. The logarithmic relationship is maintained from15 per cent down to 2 per cent the lowest moisture contenttested but above 15 per cent this air-dryrelationship no longer holds since further increase in seedmoisture content does not reduce longevity. Tentative estimatesof constant values for the improved seed viability equationare provided, and implications for long-term storage are discussed. Sesame, Sesamum indicum L., seed storage, improved viability equation, seed moisture content, seed longevity prediction 相似文献
64.
ABSTRACT. Vairimorpha invictae n. sp. infects the red imported fire ant, Solenopsis invicta Buren, in Brazil. The parasite is dimorphic, producing two morphologically distinct types of spores, which develop sequentially in the same fat cells or oenocytes in the fat body. The binucleate free spores develop from disporous sporonts; the uninucleate octospores develop from multinucleate sporonts within a sporophorous vesicle. Infected cells are transformed into large sacs which contain both types of spores in mature adult hosts. Mature free spores are often present by the time the larvae pupate, but mature octospores are found only in adult hosts. Masses of spores may be seen through the intact cuticle by low power phase-contrast microscopy; there are no other physical signs and no behavioral signs of infection. Attempts to transmit the infection in the laboratory failed. 相似文献
65.
66.
The Development of Desiccation-tolerance and Maximum Seed Quality During Seed Maturation in Six Grain Legumes 总被引:3,自引:0,他引:3
Physiological maturity, i.e. the time when seedsreach their maximum dry weight during development, occurredwhen maturation drying on the parent plant in the field hadreduced seed moisture content to approximately 60 per cent infaba bean (Vicia faba L.), lentil (Lens culinaris Medic.), chickpea(Cicer arietinum L.), white lupin (Lupinus albus L.), soya bean(Glycine max [L.] Merr.) and pea (Pisum sativum L.) The onsetof desiccation-tolerance, i.e. the ability of seeds to germinatefollowing harvest and rapid artificial drying, coincided withphysiological maturity, except in pea where it occurred a littleearlier at about 70 per cent moisture content. Maximum seedquality as determined by maximum viability, minimum seedlingabnormalities and maximum seedling size occurred in pea, chickpeaand lupin when seeds were harvested for rapid drying at physiologicalmaturity; but for maximum seed quality in the other speciesmaturation drying had to proceed further - to about 45 per centmoisture content in soya bean and to about 30 per cent moisturecontent in lentil and faba bean seed crops. Much of this variationamongst the six species, however, was due to differences inthe variation in maturity within each seed crop. Results forindividual pods showed that peak maturity, i.e. maximum seedquality following harvest and rapid artificial drying, was achievedin all six species once maturation drying had reduced the moisturecontent of the seeds to 4550 per cent. In pea, faba beanand soya bean there was a substantial decline in viability andan increase in seedling abnormalities when harvest was delayedbeyond the optimal moisture content for harvest. 相似文献
67.
68.
Equine Culicoides hypersensitivity in Florida: biting midges collected in light traps near horses 总被引:1,自引:0,他引:1
ELLIS C. GREINER VALERIE A. FADOK † EDWIN B. RABIN 《Medical and veterinary entomology》1988,2(2):129-135
Twenty-three species of Culicoides were trapped near pruritic horses during a 2-year survey in Florida. Nearly 99% of the biting midges collected were represented by Culicoides insignis Lutz, C. edeni Wirth and Blandon, C. stellifer (Coquillett), C. niger Root and Hoffman, C. haematopotus Malloch and C. venustus Hoffman. The relative contribution to the total catch by each of these species varied among collection sites. Seasonally, different species attain their largest population sizes at different times. Association of species collected in light traps with the seasonality of lesion development on the horses suggests that more than one species must be involved in causing Culicoides hypersensitivity in horses from Florida. Nulliparous females were present in most months that females of the same species were active; in some cases, species were trapped in each month of the year, particularly at the more southerly sites. The species of biting midge most likely to be involved in Culicoides hypersensitivity in horses in Florida are C. insignis, C. stellifer and C. venustus based upon their mammalophilic behaviour and seasonality. 相似文献
69.
ROSEMARY A. COLE KATHLEEN PHELPS P. R. ELLIS J. A. HARDMAN 《The Annals of applied biology》1987,110(1):135-143
Two carrot cultivars which represented contrasting levels of resistance to carrot fly, Psila rosae, were grown in a replicated field experiment at Wellesbourne in 1984–85. Seed was sown on five occasions between April and August 1984 and the crop harvested after a minimum growth in the field of 16 wk on seven occasions between August 1984 and February 1985. A highly significant correlation (r = -0.78; P > 0.001) between the levels of carrot fly damage and the concentration of chlorogenic acid in the roots enabled a model to be formulated to predict the relative predisposition to carrot fly larval damage; high levels of chlorogenic acid early in the season predisposed roots to severe attack when they were older. 相似文献
70.
A comparison was made over five seasons of carrot fly (Psila rosae) damage on two carrot cultivars, Sytan and Danvers, which represented the extremes of resistance discovered in screening trials at Wellesbourne. Plants were harvested regularly during the seasons and at each harvest the number and weight of roots was recorded and carrot fly damage was assessed using various techniques; in 1979-80 the numbers of carrot fly larvae and pupae in and around root samples were counted. The experiments confirmed repeatedly the relative resistance of cv. Sytan compared with Danvers. The estimated reduction in carrot fly larvae on Sytan relative to Danvers in early November in four seasons ranged from 40% to 67%. When tested against first generation carrot fly attack the reduction in larvae on Sytan was 54%. There were 45% fewer mines per root on Sytan resulting in less damage at each harvest in all seasons. Larvae took longer to develop on Sytan than Danvers and 18% more plants of Sytan survived carrot fly attack. Differences in seedstock, season, sowing time, generation of carrot fly, plant size and density did not account for observed differences in damage between the two cultivars. The studies indicated satisfactory practical techniques for assessing carrot fly damage in cultivar screening trials. 相似文献