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排序方式: 共有243条查询结果,搜索用时 15 毫秒
71.
Walter W. WENZEL Cornelia MESMER Eric J. FLORIDA Markus PUSCHENREITER Holger KIRCHMANN 《土壤圈》2022,32(4):543-554
Diffusive gradients in thin films (DGT) measurements have been shown to outperform other phosphorus (P) tests in soils with strong P sorption, but this has not been confirmed for moderately weathered European soils. We compared the performance of DGT in predicting wheat grain yield in Swedish long-term fertility experiments with those of standard intensity (water-extractable P (P-H2O)) and quantity (ammonium lactate-extractable P (P-AL)) tests. A Mitscherlich-type model was used to fit wheat yield response to P application rates (0, 15, 30 or 35, and 45 kg P ha-1 year-1) in each individual trial replicate to estimate the maximum yield. For trials with clear plateau-type yield responses and the goodness of fit (R2) > 0.75, relative yields (RYs) were calculated for each P treatment and plotted against the soil P test results (n=143). The goodness of the Mitscherlich-type fits decreased in the following order:DGT-measured P (P-DGT) (R2=0.35) > P-H2O (R2=0.18) > P-AL (R2=0.13). When excluding soils with P-AL:P-DGT ≥ 0.1 L g-1, R2 was considerably improved to 0.55 for P-AL, 0.46 for P-H2O, and 0.65 for P-DGT (n=61). At 95% of maximum yield, the upper limit of P deficiency for P-DGT was 44.8 (the soils with P-AL:P-DGT < 0.1 L g-1) and 61.9 μg L-1 (all soils), falling within the range reported for other European and Australian soils (6.0-142 μg L-1). We show that in the investigated Swedish soils, DGT performed better than the quantity and intensity tests, which is attributed to its ability to capture P diffusion and resupply from the soil solid phase, similar to plant roots in the rhizosphere. 相似文献
72.
In a three‐year survey several control methods of nitrogen (N) supply in strawberry were investigated. It was found that Nmin analysis could be used as a measurement of control from the beginning of the season, indicating the need of additional N supply. Leaf dry matter analysis, taken during flowering, could be used as an indicator thus making it possible to make corrections within the season, if needed. When leaf dry matter analysis was compared to leaf sap analysis, correlations were evident for the majority of nutrients, N being an important exception. It was concluded that the use of Nmin‐ and leaf dry matter analyses combined might make corrections in N fertilization within the same year possible. 相似文献
73.
Journal of Plant Diseases and Protection - In the original publication of the article, the first author name is incorrectly published. 相似文献
74.
Fleur Longuetaud Alexandre Piboule Holger Wernsdörfer Catherine Collet 《European Journal of Forest Research》2013,132(4):621-634
The objective of the study was to analyse to which extent horizontal crown plasticity reduces inter-tree competition at stand scale, and how it relates to species growth strategy. Two components of crown plasticity defined at the individual tree level (crown shape distortion, CSD and crown displacement relative to stem, CRD) were analysed and their relative importance in the reduction of competition was quantified. Inter-tree competition at stand scale was estimated using spatial pattern analysis and crown overlap estimation. Measurements were performed in a mixed broadleaved stand of Western Europe. Crown plasticity was shown to regularise the spatial distribution of crowns in comparison with the corresponding stems and to reduce inter-tree competition by optimising space occupation. A significant reduction in crown overlap was observed, mainly due to CRD and secondarily to CSD. At the species level, CSD and CRD were positively correlated. In addition, both were negatively correlated with species shade-tolerance scores. In particular, three European temperate tree species showed contrasting responses, which were related to their known specific ecological strategies. Fagus sylvatica, known to be a highly shade-tolerant species, showed large crowns, low CSD and CRD, indicating a low plasticity and suggesting a strong competitive ability. At the opposite, Quercus sp., known to be clearly less shade-tolerant, exhibited a reduced growth, associated with high CSD and CRD, indicating high crown plasticity and probably a lower competitive ability. For this species, plasticity could be described as passive. Last, Carpinus betulus, known to have a relatively good shade-tolerance, showed a contrasting behaviour with high CSD and CRD and a strong presence in the stand, suggesting high crown plasticity and a good competitive ability. In that case, plasticity was described as rather adaptive. 相似文献
75.
Khin Maung Sint Stergios Adamopoulos Gerald Koch František Hapla Holger Militz 《Wood Science and Technology》2013,47(1):43-58
Methylated N-methylol melamine (NMM) is known for its ability to enhance physico-mechanical properties, anti-fungal ability, and hydrophobicity and was therefore used to impregnate two less used and non-durable wood species from Myanmar, Bombax ceiba and Bombax insigne. Solution uptake, weight percent gain and nitrogen content were increased by increasing melamine concentrations with B. ceiba always achieving higher values compared with B. insigne. According to the leaching results, a higher degree of condensation after curing as well as a better crosslinking of NMM could be obtained at higher temperatures. However, both curing temperatures used (90 and 120 °C) resulted in almost the same amount of nitrogen fixed in the cell wall. UV microspectrophotometry confirmed the penetration of the NMM into different morphological regions of wood tissues, which was again supported by the analysis of point measurement spectra of treated and untreated specimens. 相似文献
76.
Vladimirs Biziks Bruno Andersons Ļubova Beļkova Elīna Kapača Holger Militz 《Wood Science and Technology》2013,47(4):717-735
Birch wood (Betula pendula) samples were treated in a thermal regime (140, 160, 180 °C) for 1 h and investigated by means of scanning electron microscopy (SEM). SEM microimages of the wood cross-section were taken from one and the same place before and after the thermal treatment (magnification 100–2,000×). The results of measurements of areas and linear sizes of the birch wood cells show significant changes, which depend on the thermal treatment conditions and the type of the cell: libriform, tracheid, vessel and ray. After the treatment at 180 °C, the integrity of wood morphological structure begins to break up. Voids and cracks are formed between fibres, thus leading to a decline in the mechanical properties of the wood. 相似文献
77.
Germar Eisenacher Robert Scheidemann Martin Neumann Bernhard Droste Holger Völzke 《Wood Science and Technology》2013,47(2):369-380
An extensive series of large deformation crushing tests with spruce wood specimens was conducted. Material orientation, lateral constraint and loading rate were varied. Regarding material orientation, a reduction in the softening effect and the general force level was observed with a higher fiber-load angle. A comparison with characteristics gained by application of Hankinson’s formula showed discrepancies in compression strength and the beginning of the hardening effect. Lateral constraint of the specimens caused a multiaxial stress state in the specimens, which was quantified with the applied measuring method. Further, a higher force level compared to specimens without lateral constraint and significant hardening effect at large deformations resulted. Thus, the influence of a multiaxial stress state on the force level could be determined. An increase in the loading rate led to higher force levels at any displacement value and material orientation. 相似文献
78.
Stephan Schulz Tatiana Yuyunkina Holger Pagel Lukas Y. Wick Christian Poll Thilo Streck Ellen Kandeler Michael Schloter 《Biology and Fertility of Soils》2012,48(8):933-940
In the present study, the temporal and spatial variation of the abundance of the alkane monooxygenase gene alkB and 16S rRNA genes in different soil compartments was analysed in the presence or absence of 2-methyl-4-chlorophenoxyacetic acid (MCPA) after the addition of pea litter to soil in a microcosm study. Samples were analysed shortly after litter addition (T0) and 1?week (T1), 3?weeks (T3) and 6?weeks (T6) after the addition of litter. In addition also, the quantity and quality of litter-derived alkanes was analysed and measured. The results revealed a fast and complete degradation of MCPA in all compartments throughout the experiment. Nevertheless, significant changes in the distribution patterns of short- and middle-chained alkanes suggest an interaction of MCPA and alkane degradation. alkB gene copy numbers were highly influenced by the time point of analysis and by the investigated soil compartment. Overall, an increase in alkB gene copy numbers from T0 to T3 was visible in the upper soil compartments whereas a decrease compared to T0 was measured in the deeper soil compartments. MCPA addition resulted in an increase of alkB abundance at T6. Gene copy numbers of 16S rRNA were not influenced by sampling time and soil compartment. In contrast to the control treatments, a slight increase in 16S rRNA gene copy numbers was visible at T1 and T3 compared to T0 in all soil compartments. 相似文献
79.
Seth Nii-Annang Holger Grünewald Dirk Freese Reinhard F. Hüttl Oliver Dilly 《Biology and Fertility of Soils》2009,45(5):531-538
The impact of alley cropping on post-lignite mine soils developing from quaternary deposits after 9 years of recultivation
was evaluated on the basis of microbial indicators, organic C and total N contents, and the isotope characteristics of soil
C. Soils were sampled at the 0 to 3, 3 to 10, and 10 to 30 cm depths under black locust (Robinia pseudoacacia L.), poplar (Populus spp.), the transition zone and in the middle of alley under rye (Secale cereale). There was no significant effect of vegetation on microbial properties presumably, due to the high variability, whereas organic
C and total N contents at the 0- to 3-cm layer were significantly higher under black locust and poplar than in the transition
zone and rye field. Organic C total N contents, and basal respiration, microbial biomass, and microbial quotient decreased
with soil depth. Soil organic C and total N contents were more than doubled after 9 years of recultivation, with annual C
and N accretion rate of 162 g C
org m−2 year−1 and 6 g N
t m−2 year−1. Microbial properties indicated that the soils are in early stages of development; the C isotope characteristics confirmed
that the sequestered C was predominantly from C3 plants of the alley cropping. 相似文献
80.
Tonje Økland Jørn-Frode Nordbakken Holger Lange Ingvald Røsberg Nicholas Clarke 《Scandinavian Journal of Forest Research》2016,31(8):766-776
Effects of clear-cut harvesting on ground vegetation plant species diversity and their cover are investigated at two Norway spruce sites in southern Norway, differing in climate and topography. Experimental plots at these two sites were either harvested conventionally (stem-only harvesting) or whole trees including crowns, twigs and branches were removed (whole-tree harvesting), leaving residue piles on the ground for some months. We compare the number of plant species in different groups and their cover sums before and after harvesting, and between the different treatments, using non-parametric statistical tests. An overall loss of ground vegetation biodiversity is induced by harvesting and there is a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles assembled during whole-tree harvesting and the physical damage made during the harvesting of residues in these piles. The presence of the residue piles had a clear negative impact on both species numbers and cover. Pile residue harvesting on unfrozen and snow-free soil caused more damage to the forest floor in the steep terrain at the western site compared to the eastern site. 相似文献