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81.
The costs and benefits of defensive traits in plants can have an ecological component that arises from the effect of defenses
on the natural enemies of herbivores. We tested if glandular trichomes in Datura wrightii, a trait that confers resistance to several species of herbivorous insects, impose an ecological cost by decreasing rates
of predation by the natural enemies of herbivores. For two common herbivores of D. wrightii, Lema daturaphila and Tupiocoris notatus, several generalized species of natural enemies exhibited lower rates of predation on glandular compared to non-glandular
plants. Lower rates of predation were associated with reductions in the residence time and foraging efficiency of natural
enemies on plants with glandular trichomes, but not with direct toxic effects of glandular exudate. Our results suggest that
the benefit of resistance to herbivores conferred by glandular trichomes might be offset by the detrimental effect of this
trait on the natural enemies of herbivores, and that the fitness consequences of this trichome defense might depend on the
composition and abundance of the natural-enemy community. 相似文献
82.
M. V. Sapotsky S. A. Romanova A. M. Polyakova V. I. Malinovsky 《Journal of Phytopathology》2005,153(7-8):440-444
83.
Leif Abrell † Pablo G. Guerenstein‡ Wendy L. Mechaber‡ Gert Stange†§ Thomas A. Christensen‡ Koji Nakanishi † John G. Hildebrand‡ 《Global Change Biology》2005,11(8):1272-1282
Moths can detect changes in environmental carbon dioxide (CO2) with extremely high sensitivity, but the role of CO2 in the biology of these and other insects is not well understood. Although CO2 has been demonstrated to influence egg‐laying (oviposition) behavior of the pyralid moth Cactoblastis cactorum and nectar foraging of the sphingid moth Manduca sexta, information about the generalized role of CO2 in the behavioral biology of these species is lacking. Comparative data are necessary to properly assess how the behaviors of different species may be modified by steadily rising levels of greenhouse gases in the environment. Experiments carried out in Biosphere 2 addressed whether changes in ambient CO2 levels play a role in the oviposition behaviors of M. sexta moths. In the first series of experiments, oviposition was measured inside a flight cage with different levels of nearly ambient or elevated CO2 (400, 800 or 1200 ppm). For each concentration, hostplants used as oviposition sites were grown from seed at a CO2 level that matched the environment inside the flight cage. Under homogenous levels of CO2, we observed no significant difference in oviposition behavior at the concentrations tested. In a second series of experiments, two groups of hostplants, each surrounded by a mini free‐air CO2 enrichment (FACE) ring, were assembled inside a flight cage. In this choice test, a dynamic plume of artificially high CO2 was generated around one group of test plants, while ambient CO2 was released around the second (control) group. After eggs were counted on both plant groups, M. sexta females showed a small preference for ovipositing on the control plants. Therefore, in contrast to C. cactorum females tested under similar dynamic flow conditions, M. sexta female oviposition was not strongly inhibited by elevated CO2. To investigate this phenomenon further, we used electrophysiological recording and found that the CO2 receptor cells in M. sexta, unlike those in C. cactorum, are not readily affected by elevated levels of ambient CO2. These findings therefore suggest that elevated background levels of CO2 affect the physiology of the CO2 detection system of M. sexta to a lesser extent than that of C. cactorum, and this correlates well with the observed differences in oviposition behavior between the two species under elevated levels of environmental CO2. Hostplants of C. cactorum are crassulacean acid metabolism plants that generate nocturnal CO2 sinks on the cladode surfaces, whereas, M. sexta hostplants are nocturnal sources of respiratory CO2. We hypothesize that the abrupt and continuing increase in global ambient CO2 levels will differentially alter the behavior and physiology of moths that use CO2 sinks and sources as sensory cues to find hostplants. 相似文献
84.
经紫外诱变氯酸钾筛选,得到一个低硝酸还原酶(NADH:硝酸氧化还原酶.EC1.6.6.1.,以下简写为NR)活力的细胞株。其主要特征:NR活力低,约为正常型的1/5;对氯酸钾具有较强的抗性;不适合在单纯以硝酸盐为氮源的培养基上生长,能在以(NH_4)_2SO_4为唯一氮源的培养基上生长。蛋白电泳表明,此细胞株与正常型有不同的蛋白带。这些特征在没有选择压力的培养基上培养二年后,仍保持不变,说明此细胞株是一个遗传型的变异株。 相似文献
85.
Structures, function, and transformational changes of the sugar chains of glycohormones 总被引:1,自引:0,他引:1
A Kobata 《Journal of cellular biochemistry》1988,37(1):79-90
Human chorionic gonadotropin (hCG), human luteinizing hormone, human thyroid-stimulating hormone, and human follicle-stimulating hormone are closely related family of proteins which share a common alpha-subunit. However, their sugar moieties are quite different. hCG contains five acidic asparagine-linked sugar chains. These five sugar chains are derived by sialylation from three neutral oligosaccharides: two biantennary (N-1 and N-2) and one monoantennary (N-3) complex-type oligosaccharides. Although hCG purified from the urine of pregnant women is more enriched in sialylated sugar chains than that purified from placenta, the molar ratio of N-1, N-2, and N-3 of these two hCGs are the same (1:2:1). Comparative study of the sugar moieties of the alpha- and beta-subunits of hCG revealed that alpha contains 1 mol each of N-2 and N-3, while beta contains 1 mol each of N-1 and N-2. This specific distribution of oligosaccharides at the four asparagine loci of the hCG molecule is now helping us to consider the functional role of the sugar moiety of glycohormones. hCG is produced not only by the trophoblast but also by various trophoblastic diseases. The hCGs purified from the urine of patients with hydatidiform mole contain the same oligosaccharides as normal hCG. However, those from the urine of choriocarcinoma patients contain five additional neutral oligosaccharides. In contrast, hCGs from invasive-mole patients contain three of the five oligosaccharides, specifically found in choriocarcinoma hCGs. The malignant transformational change of the sugar moiety of hCG can be explained by an increase of a fucosyltransferase, which forms the Fuc alpha 1----6GlcNAc group and by ectopic expression and subsequent modification of N-acetylglucosaminyltransferase IV. The appearance of tumor-specific sugar chains of hCG has been used to develop a new diagnostic method for invasive mole and choriocarcinoma. 相似文献
86.
The effect of abiotic stresses such as light, dark conditions and formaldehyde (HCHO) deprivation with dimedone, was investigated on the growth and HCHO level in Datura innoxia Mill. callus cultures. The HCHO as its dimedone adduct form (formaldemethone) was isolated and characterised by overpressured layer chromatography (OPLC). In the cultures cultivated both in dimedone free and dimedone containing medium the endogenous HCHO level was in general higher in light than in the dark. The HCHO deprivation with dimedone did not influence basically the actual endogenous HCHO level in Datura callus tissues, however, the tissue mass was changed. 相似文献
87.
The utilisation and accumulation of 15N-labeled metabolites by a 15N-labeled transformed root culture of Daturastramonium L. was investigated by in vivo 15N-nuclear-magnetic-resonance (NMR) spectroscopy. After resuspension in spent growth medium, the pools of [15N]glutamate and [15N]glutamine were rapidly depleted and there was an increase in the 15N-NMR signals from conjugated putrescines and hyoscyamine. The signal from the conjugated putrescines passed through a maximum
2 d after the roots were resuspended, and it was concluded that putrescine could be stored as putrescine conjugates prior
to its utilisation in other pathways. The transient accumulation of 15N-label in the hydroxy-cinnamoylputrescines was reduced when the de-differentiation of the root cultures into a suspension
culture was initiated by exposure to a medium containing α-napthaleneacetic acid and kinetin. This led to the hypothesis that
phytohormone-induced de-differentiation of the root cultures required the presence of free polyamines, and this was tested
using two potent inhibitors of putrescine biosynthesis, dl-α-difluoromethylarginine and dl-α-difluoromethylornithine. In-vivo 15N-NMR spectra of roots grown in 15N-enriched medium supplemented with these inhibitors showed that the 15N-labelling of the conjugated polyamines and hyoscyamine was markedly reduced. dl-α-difluoromethylarginine also prevented the phytohormone induced de-differentiation of the root cultures, and this effect
could be reversed by the supply of exogenous putrescine. Thus the supply of putrescine appears to play a crucial role in mediating
the phytohormone induced de-differentiation of the root culture.
Received: 13 September 1997 / Accepted: 12 November 1997 相似文献
88.
I. E. Maldonado-Mendoza T. Ayora-Talavera V. M. Loyola-Vargas 《Plant Cell, Tissue and Organ Culture》1993,33(3):321-329
The aim of this paper was the screening of the variability of growth patterns, biomass and tropane alkaloid production of
500 hairy root lines ofDatura stramonium. Data on the long term stability in alkaloid production of these lines for more than 5 years are also provided. In an effort
to obtain high alkaloid-producing root clones, it is demonstrated that systematic selection is necessary. Comparisons are
made, mainly concerning alkaloid production and its stability, with normal root cultures initiated from the same mother plants
when necessary. Hairy root cultures were found to have a hyoscyamine and scopolamine bioproductivity of 2 orders of magnitude
higher than mother plants. 相似文献
89.
THE EFFECTS OF ELEVATED CO2 ON PLANTS 总被引:6,自引:2,他引:4
90.
In haploid, diploid, triploid, tetraploid and hexaploid cytotypes of the scopalamine-yieldingDatura innoxia, the amino acid profiles were studied. The results suggest that the amino acid composition is influenced quantitatively by increasing ploidy levels, but in an irregular way. 相似文献