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51.
G. Halldórsson † V. Sigurdsson Æ. TH. Thórsson E. S. Oddsdóttir A. Sigurgeirsson K. Anamthawat-Jónsson 《Agricultural and Forest Entomology》2004,6(1):31-37
Abstract 1 The Random Amplified Polymorphic DNA (RAPD) method was used to investigate genetic diversity of anholocyclic populations of the green spruce aphid, Elatobium abietinum Walker, in north‐west Europe. 2 The results showed that the aphid in this region was divided genetically into three major groups. Aphids from the British Isles and north‐west France comprised the first group, the second group consisted of aphids from Denmark and Iceland, and the third group consisted of aphids from Norway. 3 The results indicated a significant level of gene flow within and between sites and geographical regions, especially in the British Isles and north‐west France. Lateral migration of the aphid and/or sexual reproduction is likely to have facilitated the gene flow. 4 The implications of these findings on management of the green spruce aphid are discussed. 相似文献
52.
The chemical composition and energy contents of copepods and cladocerans in relation to their size 总被引:4,自引:0,他引:4
The chemical composition and energy contents of four different species of cladocerans, one species of a calenoid copepod, and mixed samples of four species of cyclopoid copepods were quantitatively determined. The relative chemical composition, expressed as a percentage of the total organic matter (excluding chitin) of each of the different species analysed, were very similar. The mean relative composition for all species was 71·2% protein, 9·5% carbohydrates, 19·3% lipids, 16·5% total nitrogen and 2·1% total phosphate–phosphorus. A substantial amount of the total nitrogen was found to be non-protein nitrogen (mean of 23·3% of total nitrogen). The calorific value was calculated from the estimated amounts of proteins, carbohydrates and lipids using conversion factors. The relationship between the calculated organic matter and the chemical oxygen demand (COD) was found to be constant and did not vary much for the different species. The ratio of total organic matter to COD has a mean value of 0·51. Calorific values ranged from 5847 to 6353 cal/g total organic matter. The amounts of chemical substances or energy contents per individual Copepoda or Cladocera were calculated. Regression lines together with their correlation coefficients have been computed to describe the relationship between the amount of chemical constituents and energy contents per individual, and the length of the individual. The results are extensively compared with those given in the literature and differences are discussed. 相似文献
53.
S. DEMETER G. HORVÁTH F. JOÓ N. HALÁSZ ÁGNES FALUDI-DÁNIEL 《Physiologia plantarum》1974,32(3):222-227
Stacking of chloroplast lamellae, isolated from normal and carotenoid mutant chloroplasts of maize (Zea mays L.), was determined after a high-salt treatment. Stacking of isolated lamellae under favourable ionic conditions was almost identical with that occurring in intact chloroplasts; thus, differences in granum content could be attributed to the architectural properties of lamellae. Gaussian analyses, performed on the red band of room temperature absorption spectra, have shown that chloroplasts with lamellae of high stacking capacity contain relatively more Chl a662 than chloroplasts containing lamellae of low stacking capacity. The presence of Chl a705–708 was characteristic of preparations containing considerable amounts of stroma lamellae. 相似文献
54.
The role of natural and synthetic auxins in regulation of ion transport and ATPase activity was studied in rice roots (Oryza sativa L. cv. Dunghan Shah). In vivo treatment of seedlings with 2,4-dichlorophenoxyacetic acid at 2 × 10?6M for a short period enhanced subsequent Ca2+ stimulated K+ influx and ATPase activity, while a longer treatment diminished both K+ influx and ATPase activity. Indoleacetic acid at 10?10–10?8M induced ATPase activity. In in vitro experiments both 2,4-dichloro phenoxyacetic acid and indoleacetic acid (10?10–10?8M) stimulated Ca2+, K+-ATPase activity of a plasmalemma rich micro somal fraction from the roots. Acetone extracted ATPase preparations lost their activity. The enzyme regained its activity and its sensitivity towards ions (Ca2++ K+) when reconstituted with phosphatidyl choline. Addition of auxins also indicated that the presence of the lipid was necessary in the interaction between the ATPase and auxins. Auxins and ions probably interact with the intact ATPase lipoprotein complex, which may possess a receptor site for the auxins, possibly as a sub unit. 相似文献
55.
ABSTRACT. Fixed honey-bees were conditioned to a scent in a one-trial learning paradigm. In contrast to free-flying colour-conditioned bees, fixed scent-conditioned bees do not show a biphasic time dependence of the conditioned response. Small metal probes were used to cool localized areas of the antennal lobes, alpha-lobes, and calyces of the mushroom bodies of the brain at various times after conditioning. Localized cooling impaired the formation of memory in all three structures. The susceptibility to impairment after conditioning lasted approximately 3 min in the antennal lobes, 7 min in the alpha-lobes, and 10 min in the calyx area. It was possible to determine the influence of the contralateral hemisphere (relative to the learning antenna) by conditioning bees with only one antenna. No contralateral impairment was found in the antennal lobes; there were minor effects in the alphalobes; contralateral cooling led to reductions of the conditioned response only in the calyx area. The temperature dependence of memory impairment was different for the antennal lobes and the mushroom bodies (alpha-lobes and calyces). The latter were most sensitive to cooling at 5°C. No correlation between cooling duration and impairment of memory was found in the antennal lobes, but there was a linear relation between impairment and cooling duration in the alpha-lobes. Brief cooling (5 or 10 s) resulted in significant impairment of memory formation only in the calyx area. A series of control experiments proved that the impairment of memory is due to a reversible block of neural activity. It was possible to show that the impairment is specific for the three neural structures analysed, by cooling the lobula of the optic system at various times after conditioning. Lesions of the brain or application of KCl also resulted in time-dependent reductions of the conditioned response. Cooling the entire animal at various times after conditioning led to similar memory impairment to that resulting from localized cooling of the alphalobes. 相似文献
56.
Hypophysiotropic Centers in the Brain of Amphibians and Fish 总被引:2,自引:0,他引:2
The subject is the localization of three different hypophysiotropiccenters in the brain of amphibians and fish. The thyrotropic hormone-releasing hormone (TRH) in Xenapus mayoriginate from the dorsal magno-cellular neurons of the preopticnucleus. This hypothesis is based on correlative changes betweenthese cells and alterations in thyroid activity during metamorphosis.Experimental data are in support of a functional relationshipbetween certain preoptic neurons and the thyrotropic activityof the pituitary. The MSH inhibiting activity of the hypothalamus is effectedby means of an aminergic innervation of the pars intermediain amphibians, teleosts and elasmobranchs. In amphibians theaminergic fibers originate from the caudal part of the paraventricularorgan (PVO); in elasmobranchs probably from the nucleus mediushypothalamicus(NMI); in teleosts the origin still has to beinvestigated. Two centers producing gonadotropic hormone-releasing hormone(GRH) have been demonstrated. Lesion experiments lead to thehypothesis that GRH is produced in the caudal hypothalamus,i.e., in the nucleus infundibularis ventralis of amphibiansand in the nucleus lateralis tuberis of fishes. ImmunoHuorescencestudies indicate in both groups the presence of neurons, infront of the preoptic area in the telencephalon, and these neuronsare immuno-reactive with anti-mammalian LH-RH. 相似文献
57.
CREVECOEUR M.; PENEL C.; GREPPIN H.; GASPAR TH. 《Journal of experimental botany》1986,37(8):1218-1224
Spinach plants were induced to flower by transferring them fromshort days to continuous light. Their leaf laminae releasedmore ethylene than those from vegetative plants. These leavesalso exhibited a greater capacity to convert exogenous ACC intoethylene. Cell wall preparations from the leaves of continuouslyilluminated plants also converted exogenous ACC into ethylenemore readily than extracts from short day plants. These effectsand also those previously reported for peroxidases appear verysimilar to these brought about by various environmental stressessuch as pollution and mechanical irritation. Key words: Ethylene, floral induction, stress, photoperiod, spinach 相似文献
58.
New Insights into ABA-Mediated Processes 总被引:2,自引:0,他引:2
59.
THÉOPHILE KAZMIERCZAK VÉRONIQUE GRUBER FLORIAN FRUGIER MATHILDE CLEMENT PIERRE FRENDO DIDIER HEROUART ERIC BONCOMPAGNI 《Plant, cell & environment》2014,37(3):658-669
PRAF proteins are present in all plants, but their functions remain unclear. We investigated the role of one member of the PRAF family, MtZR1, on the development of roots and nitrogen‐fixing nodules in Medicago truncatula. We found that MtZR1 was expressed in all M. truncatula organs. Spatiotemporal analysis showed that MtZR1 expression in M. truncatula roots was mostly limited to the root meristem and the vascular bundles of mature nodules. MtZR1 expression in root nodules was down‐regulated in response to various abiotic stresses known to affect nitrogen fixation efficiency. The down‐regulation of MtZR1 expression by RNA interference in transgenic roots decreased root growth and impaired nodule development and function. MtZR1 overexpression resulted in longer roots and significant changes to nodule development. Our data thus indicate that MtZR1 is involved in the development of roots and nodules. To our knowledge, this work provides the first in vivo experimental evidence of a biological role for a typical PRAF protein in plants. 相似文献
60.
Sonja Melman Ellen NC Schoorel Carmen Dirksen Anneke Kwee Luc Smits Froukje de Boer Madelaine Jonkers Mallory D Woiski Ben Willem J Mol Johannes PR Doornbos Harry Visser Anjoke JM Huisjes Martina M Porath Friso MC Delemarre Simone MI Kuppens Robert Aardenburg Ivo MA Van Dooren Francis PJM Vrouenraets Frans TH Lim Gunilla Kleiverda Paulien CM van der Salm Karin de Boer Marko J Sikkema Jan G Nijhuis Rosella PMG Hermens Hubertina CJ Scheepers 《Implementation science : IS》2013,8(1):1-8