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91.
92.
Effects of a soil fulvic acid on the growth and nutrient content of cucumber (Cucumis sativus) plants 总被引:3,自引:0,他引:3
Summary Cucumber (Cucumis sativus) plants were grown in Hoagland solution to which 20 to 2000 ppm of a soil fulvic acid (FA) were added. The addition of 100
to 300 ppm of FA produced highly significant increases in the growth and development of above and below ground plant parts,
in the uptake of nutrient elements (N, P, K, Ca, Mg, Cu, Fe and Zn), and in the formation of numbers of flowers per plant.
Effects of adding 500 and more ppm of FA were less beneficial. 相似文献
93.
Metabolism of abscisic acid (ABA) was studied after wilting and upon recovery from water stress in individual, detached leaves of Phaseolus vulgaris L. (red kidney bean). Loss of turgor was correlated with accumulation of ABA and its metabolites, resulting in a 10-fold increase in the level of phaseic acid (PA) and a doubling of the level of conjugated ABA. The level of conjugated ABA in turgid leaves was no higher than that of the free acid. These results indicate that accumulation of ABA in wilted leaves resulted from a stimulation of ABA synthesis, rather than from a release from a conjugated form or from inhibition of the metabolism of ABA. The rate of synthesis of ABA was at its maximum between 2.5 and 5 h after turgor was lost, and slackened there-after. In wilted leaves, the rate of conversion of ABA to PA climbed steadly until it matched the rate of synthesis, after about 7.5 h. Upon rehydration of sections from wilted leaves, the rate of synthesis of ABA dropped close to zero within about 3 h, while the rate of conversion to PA accelerated. Formation of PA was two to four times faster than in sections maintained in the wilted condition; it reached a rate sufficient to convert almost one-half of the ABA present in the tissue to PA within 1 h. In contrast, the alternate route of metabolism of ABA, synthesis of conjugated ABA, was not stimulated by rehydration. The role of turgor in the stimulation of the conversion of ABA to PA was investigated. When leaves that had been wilted for 5 h were rehydrated to different degrees, the amount of ABA which disappeared, or that of PA which accumulated during the next 3 h, did not depend linearly on the water potential of the rehydrated leaf. Rather, re-establishment of the slightest positive turgor was sufficient to result in maximum stimulation of conversion of ABA to PA.Abbreviations ABA
abscisic acid
- DPA
dihydrophaseic acid
- PA
phaseic acid
- leaf
leaf water potential
-
osmotic pressure 相似文献
94.
Summary Observations by light, transmission electron and scanning electron microscopy have shown that intercellular spaces (ICS) are formed schizogenously in expanding leaves ofPhaseolus vulgaris. ICS formation occurs in predictable positions at the junctions between three or more cells, and follows three phases of development. The first, initiation, phase occurs soon after cell division, and is marked by the formation of an electron-dense osmiophilic body, probably proteinaceous, at the end of the cell plate/middle lamella of the daughter cell wall and across the adjacent piece of the primary wall of the mother cell. This part of the mother cell wall is digested, involving cellulolysis. The second phase, of cell separation, is marked by the first appearance of the ICS. InPhaseolus primary leaves this phase begins about day 3 after sowing, at which time the leaf area is about 1 cm2. In the final enlargement phase, lysis of cell wall material continues in the region of the middle lamella, and mechanical tensions arising from the rapid expansion of the lamina lead to further separation of the mesophyll cells so that spaces enlarge and merge. 相似文献
95.
Leaves of 26 grass, herb, shrub and tree species were collected from mesotrophic grasslands to assess natural variability in bulk, fatty acid and monosaccharide δ13C values under different grazing management (cattle- or deer-grazed) on three sample dates (May, July and October) such that interspecific and spatiotemporal variations in whole leaf tissues and compound-specific δ13C values could be determined. The total mean leaf bulk δ13C value for plants was −28.9‰ with a range of values spanning 7.5‰. Significant interspecific variation between bulk leaf δ13C values was only determined in October (P = <0.001) when δ13C values of the leaf tissues from both sites was on average 1.5‰ depleted compared to during July and May. Samples from May were significantly different between fields (P = 0.03) indicating an effect from deer- or cattle-grazing in young leaves. The average individual monosaccharide δ13C value was 0.8‰ higher compared with whole leaf tissues. Monosaccharides were the most abundant components of leaf biomass, i.e. arabinose, xylose, mannose, galactose and glucose, and therefore, fluctuations in their individual δ13C values had a major influence on bulk δ13C values. An average depletion of ca. 1‰ in the bulk δ13C values of leaves from the deer-grazed field compared to the cattle-grazed field could be explained by a general depletion of 1.1‰ in glucose δ13C values, as glucose constituted >50% total leaf monosaccharides. In October, δ13C values of all monosaccharides varied between species, with significant variation in δ13C values of mannose and glucose in July, and mannose in May. This provided an explanation for the noted variability in the tissue bulk δ13C values observed in October 1999. The fatty acids C16:0, C18:2 and C18:3 were highly abundant in all plant species. Fatty acid δ13C values were lower than those of bulk leaf tissues; average values of −37.4‰ (C16:0), −37.0‰ (C18:2) and −36.5‰ (C18:3) were determined. There was significant interspecific variation in the δ13C values of all individual fatty acids during October and July, but only for C18:2 in May (P = <0.05). This indicated that seasonal trends observed in the δ13C values of individual fatty acids were inherited from the isotopic composition of primary photosynthate. However, although wide diversity in δ13C values of grassland plants ascribed to grazing management, interspecific and spatiotemporal influences was revealed, significant trends (P = <0.0001) for fatty acid and monosaccharide δ13C values: δ13C16:0 < δ13C18:2 < δ13C18:3 and δ13Carabinose > δ13Cxylose > δ13Cglucose > δ13Cgalactose, respectively, previously described, appear consistent across a wide range of species at different times of the year in fields under different grazing regimes. 相似文献
96.
Sadia Saif Arifa Tahir Tayyaba Asim Yongsheng Chen Mujeeb Khan Syed Farooq Adil 《Saudi Journal of Biological Sciences》2019,26(7):1364-1371
In this study, the leaves extract of Cordia myxa, has been used for the first time to synthesize zinc oxide (ZnO) hierarchical microstructures. The solution combustion method was employed as a self-sustaining reaction between zinc nitrate and the leaves extract. The surface properties of leaves mediated ZnO microstructures were determined by UV–Visible spectral analysis, Fourier transform infrared (FT-IR), Cold field emission-scanning electron microscopy (CFE-SEM), Energy dispersive X-ray (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In addition, the effect of the leaves extract concentration on ZnO structures, size and surface properties was also studied. ZnO structures synthesized employing C. myxa were found to be hexagonal, triangular and round in shape which was determined using CFE-SEM. X-ray diffraction (XRD) analysis confirmed the crystalline nature of compounds. Furthermore, C. myxa mediated ZnO microstructures shows good bactericidal activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. 相似文献
97.
《Saudi Journal of Biological Sciences》2022,29(1):472-479
Bidens bipinnata is widely utilized medicinal plant for treatment of diseases like malaria, sore throat, acute nephritis and dysentery. However, despite its traditional uses Bidens bipinnata is not widely explored for its antimicrobial effect. Thus, the current study is aimed to form antimicrobial activity report of Bidens bipinnata extracts, along with isolation and evaluation of antibacterial activity of the isolated compounds through bioassay-guided purification. Hexane extract of its leaves has appeared to be most active thus it is exposed to automated column chromatography. Further purification using High-performance liquid chromatography has led to isolation of active peaks, identified by Gas Chromatography-mass spectrometry, as 16-Pregnenolone and 9-Octadecenoic acid (Z)-, methyl ester. Their antimicrobial activity was confirmed via broth dilution procedure on Staphylococcus aureus, 16-Pregnenolone revealed a strong antimicrobial activity with MIC50 of 72 μg/mL whereas 9-Octadecenoic acid (Z)-, methyl ester display an MIC50 of >250 μg/mL. Present study is the first report on isolation of these compounds from Bidens bipinnata. 相似文献
98.
C. U. Hesemann G. Schröder 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1982,62(4):325-328
Summary The nuclear DNA content of rye leaf cells was cytophotometrically determined. At the commencement of differentiation nuclei in rye leaves remain standing at G1 phase. With further differentiation a remarkable diminution of nuclear DNA content occurs in diploid cells. The largest number of cells showing a loss of nuclear DNA content were found in the top of the leaf. The age of the leaf and the extent of diminution in nuclear DNA content are correlated.Dedicated to Professor Dr. J. Straub in honour of his 70th birthday 相似文献
99.
橡胶树叶片高光谱特征分析 总被引:4,自引:1,他引:3
从光谱曲线特征和光谱变换特征分析橡胶树(Hevea brasiliensis)叶片反射曲线特征.结果表明,蓝边、红边、黄边位置特征分别出现于525 nm、725 nm、550 nm波段附近,红谷位置特征变化较大,并提取了红边积分面积等重要光谱变量特征.叶片氮含量与反射光谱的相关分析表明橡胶树叶片氮素敏感波段为700~1300 nm,其中730 nm处相关性最好,达到0.8422的极显著水平,以730 nm处的反射率与叶片氮含量建立线性模型,其复相关系数R2达到0.7094. 相似文献
100.
Leaf traits and associated ecosystem characteristics across subtropical and timberline forests in the Gongga Mountains,Eastern Tibetan Plateau 总被引:20,自引:0,他引:20
Knowledge of how leaf characteristics might be used to deduce information on ecosystem functioning and how this scaling task could be done is limited. In this study, we present field data for leaf lifespan, specific leaf area (SLA) and mass and area-based leaf nitrogen concentrations (Nmass, Narea) of dominant tree species and the associated stand foliage N-pool, leaf area index (LAI), root biomass, aboveground biomass, net primary productivity (NPP) and soil available-N content in six undisturbed forest plots along subtropical to timberline gradients on the eastern slope of the Gongga Mountains. We developed a methodology to calculate the whole-canopy mean leaf traits to include all tree species (groups) in each of the six plots through a series of weighted averages scaled up from leaf-level measurements. These defined whole-canopy mean leaf traits were equivalent to the traits of a leaf in regard to their interrelationships and altitudinal trends, but were more useful for large-scale pattern analysis of ecosystem structure and function. The whole-canopy mean leaf lifespan and leaf Nmass mainly showed significant relationships with stand foliage N-pool, NPP, LAI and root biomass. In general, as elevation increased, the whole-canopy mean leaf lifespan and leaf Narea and stand LAI and foliage N-pool increased to their maximum, whereas the whole-canopy mean SLA and leaf Nmass and stand NPP and root biomass decreased from their maximum. The whole-canopy mean leaf lifespan and stand foliage N-pool both converged towards threshold-like logistic relationships with annual mean temperature and soil available-N variables. Our results are further supported by additional literature data in the Americas and eastern China. 相似文献