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11.
Tobacco leaves depleted of starch, were detached and allowedto assimilate equal amounts of 14CO2 and 12CO2in succession,and vice versa. Distribution of radioactivity in starch, andsugars was determined after assimilation and after disks cutfrom the leaves had been kept in darkness for times up to 40hours. The amount and activity of the CO2 was also determined.14C and 12C were incorporated in equal amounts into starch independentlyof the order in which they were supplied. In contrast sucrosehad high activity 14C was given last, and hexose a low one.The reverse was true when 12C was given last. Activity of respiratoryCO2 was slightly higher when 14C was assimilated last as comparedwith 12C. In the dark only 14C or 12C was at first lost fromstarch, in accordance or removal of discrete layers. Analyticalresults show that starch is the main respiratory substrate andto account for the redistribution of radioactivity in passageto CO2 it is concluded that sucrose occurs at two sites separatedinter-or intra-cellularly, one of which is in equilibrium withthe system intrconverting starch and CO2 and at the other hexosesare produced by inversion. A starch-like polysaccharide is formedduring assimilation which persists in the dark and there isa significant contribution to respiration of carbon from non-carbohydratesources when leaf disks are kept on the dark. 相似文献
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STUDIES ON PLANT CUTICLE 总被引:2,自引:0,他引:2
The waxy coverings of the leaves of different species of plant have been fractionated into wax, acidic, volatile and oil components. The levels of the waxy deposits on the leaves and the relative proportions of the principal components of the waxy coverings differed widely. Wax predominated in the waxy coverings of the leaves of cabbage and cauliflower and acidic materials in those of apple and pear.
The role of ether-soluble acidic constituents in a possible defensive mechanism of leaves against fungi, the contribution of water-soluble acidic constituents to the toxic action of copper fungicides and the influence of the waxy covering on spray deposition, phytotoxicity and the behaviour of DDT deposits on leaves are discussed. Earlier work on the nature of leaf wax components is reviewed. 相似文献
The role of ether-soluble acidic constituents in a possible defensive mechanism of leaves against fungi, the contribution of water-soluble acidic constituents to the toxic action of copper fungicides and the influence of the waxy covering on spray deposition, phytotoxicity and the behaviour of DDT deposits on leaves are discussed. Earlier work on the nature of leaf wax components is reviewed. 相似文献
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Tissue-invasive pollen tube branching occurs in an Australianshrub, Grevillea banksii R.Br. (Proteaceae). Parenchyma andphloem of the ovary wall are soon infiltrated after fertilization,by intercellular branches and the lumina of xylem elements areentered. Ovular tissues are not affected. Grevillea banksii, pollen, haustoria, ovary wall 相似文献
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Monitoring the persistence of Laccaria bicolor as an ectomycorrhizal symbiont of nursery-grown Douglas fir by PCR of the rDNA intergenic spacer 总被引:2,自引:0,他引:2
B. HENRION C. DI BATTISTA D. BOUCHARD D. VAIRELLES B. D. THOMPSON † F. LE TACON F. MARTIN 《Molecular ecology》1994,3(6):571-580
The large-scale inoculation of selected beneficial ectomycorrhizal fungi in forest nurseries has generated renewed interest in the ecology of these symbiotic fungi. However, information on the dissemination and persistence of introduced symbionts is scarce due to the limitation of the current identification methods. To identify ectomycorrhizal fungi on single root tips, we investigated the polymorphism of the PCR-amplified ribosomal DNA intergenic spacer (IGS) from a wide range of ectomycorrhizal fungi. To investigate the reliability of this molecular approach in large-scale surveys, the dissemination and persistence on Douglas fir seedlings of the introduced Laccaria bicolor S238N were assessed in a forest nursery in the Massif Central (France). Several hundred ectomycorrhizas and fruiting bodies were sampled from plots where control and L. bicolor inoculated-Douglas fir seedlings were grown for 1.5 years. PCR typing of mycorrhizas indicated that trees inoculated with L. bicolor S238N remained exclusively colonized by that isolate (or sexually derived isolates) for the entire test period. In contrast, control seedlings were infected by indigenous isolates of Laccaria laccata and Thelephora terrestris. The molecular evidence for the persistence of the introduced mycobiont despite the competition from indigenous isolates of the same species provides further illustration of the potential of exotic species for large-scale microbial application. 相似文献
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Winter Ciliates in a British Columbian Fjord: Six New Species and an Analysis of Ciliate Putative Prey 总被引:1,自引:0,他引:1
ABSTRACT. This work provides the first study of North Pacific planktonic ciliates by quantitative protargol staining. Triplicate water bottle samples were collected at a depth of 2 m (above the shallow pycnocline) at six stations in Indian Arm, British Columbia, on February 15, 1990, and February 26, 1991. Thirty-six ciliate species were observed. Six new species are described from protargolstained specimens: Strombidium lynni n. sp., Strombidium taylori n. sp., Strombidium basimorphum n. sp., Slrombidiurn ventropinnum n. sp., Strobilidium undinum n. sp., and Urotricha cyrtonucleata n. sp.
Ciliate abundance varied significantly (ANOVA, α= 0.05) between sampling sites, ranging from 550 to 6,800 cells/liter in 1990 and from 1,800 to 7,900 cells/liter in 1991. Biomass also varied significantly (ANOVA, α= 0.05) ranging from 3.7 × 105 to 3.3 × 106 pg carbon/liter in 1990 and 3.04 × 106 − 6.97 × 106 pg carbon/liter in 1991. Putative prey were enumerated in three size fractions (1.5–5 μm, 5–10 μm and 10–25 μm). The source of variation in ciliate abundance and biomass was not identified. Parameters of salinity, temperature, putative prey, chlorophyll a and pycnocline depth did not significantly correlate with ciliate biomass or abundance (α= 0.05). 相似文献
Ciliate abundance varied significantly (ANOVA, α= 0.05) between sampling sites, ranging from 550 to 6,800 cells/liter in 1990 and from 1,800 to 7,900 cells/liter in 1991. Biomass also varied significantly (ANOVA, α= 0.05) ranging from 3.7 × 10
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