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1.
The purpose of this study was to define normal gross anatomic structures in the equine stifle with magnetic resonance images. Magnetic resonance (MR) images were made in sagittal, 15° supinated, transverse, and dorsal planes of two equine stifles. The MR images were scrutinized by comparing MR images to dissection specimens and frozen cross sections of stifle joints. Sagittal and 15° supinated images were the most valuable in assessing articular cartilage, subchondral bone, and soft tissue structures within the joint. Cranial and caudal cruciate ligaments, medial and lateral menisci, meniscotibial and meniscofemoral ligaments, long digital extensor tendon, and patellar ligaments were easily evaluated. MR images provided substantially more gross anatomical information than the currently available imaging modalities.  相似文献   
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Journal of Plant Diseases and Protection - Mastreviruses are an emerging group of viruses transmitted by leafhoppers and infect both monocot and dicot plants. Chickpea chlorotic dwarf virus...  相似文献   
4.
An image-based stated choice approach was used to investigate the conditions determining why visitors to an urban forest in Vienna feel crowded or not. Respondents (N=213) evaluated several sets of images depicting trail use scenarios with different levels of social crowding conditions and several types of social interferences. Forest users were segmented into three groups based on their global evaluations of use levels during weekends and work days, resulting in a crowding-averse, a crowding-tolerant, and a crowding-indifferent segment. Crowding-averse respondents reacted much more negatively to scenarios with high-use levels, heterogeneous trail use conditions, and violations of personal minimum spatial requirements caused by the presence of others. This user group felt overcrowded because social conditions experienced in the area interfered with their main visiting goals, especially to walk with their dog unleashed and to recreate. By contrast, crowding-tolerant respondents disliked very low-use and high-use situations, and preferred a certain amount of social stimulation in the form of some encounters, and more heterogeneous trail use conditions.  相似文献   
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Soil organic carbon (SOC) and nitrogen (N) are two of the most important indicators for agricultural productivity. The primary objective of this study was to investigate the changes in SOC and N in the deep soil profile (up to 100 cm) and their relationships with crop productivity under the influence of long-term (since 1990) fertilization in the wheat-maize cropping system. Treatments included CK (control), NP (inorganic N and phosphorus (P) fertilizers), NPK (inorganic N, P and potassium fertilizers), NPKM (NPK plus manure), and M (manure). Crop yield and the properties of topsoil were measured yearly from 2001 to 2009. C and N contents were measured at five different depths in 2001 and 2009. The results showed that wheat and maize yields decreased between 2001 and 2009 under the inorganic fertilizer (NP and NPK) treatments. The average yield between 2001 and 2009 under the NP, NPK, NPKM, and M treatments (compared with the CK treatment) increased by 38, 115, 383, and 381%, respectively, for wheat and 348, 891, 2 738, and 1 845%, respectively, for maize. Different long-term fertilization treatments significantly changed coarse free particulate (cfPOC), fine free particulate (ffPOC), intramicroaggregate particulate (iPOC), and mineral-associated (mSOC) organic carbon fractions. In the experimental years of 2001 and 2009, soil fractions occurred in the following order for all treatments: mSOC>cfPOC>iPOC>ffPOC. All fractions were higher under the manure application treatments than under the inorganic fertilization treatments. Compared to the inorganic fertilization treatments, manure input enhanced the stocks of SOC and total N in the surface layer (0–20 cm) but decreased SOC and N in the deep soil layer (80–100 cm). This reveals the efficiency of manure in increasing yield productivity and decreasing risk of vertical loss of nutrients, especially N, compared to inorganic fertilization treatments. The findings provide opportunities for understanding deep soil C and N dynamics, which could help mitigate climate change impact on agricultural production and maintain soil health.  相似文献   
6.
Humus properties in various Ap horizons from field plots, that have been cultivated in long-term experiments under different management conditions, were investigated by pyrolysis-field ionization mass spectrometry (Py-FIMS) and 13C-NMR spectroscopy. The results of Py-FIMS were evaluated by correlation and principal component analysis from reproducible data sets of bulk soil samples and extracted humic substances, and allowed a distinct discrimination on the basis of humus quality and composition. The chemical subunits suitable for discrimination are the major plant constituents carbohydrates, lignin, and proteinaceous materials as well as their humification products. The contribution of these compound classes to soil organic matter decreased with the intensity of management. CPMAS and solution 13C NMR spectra of soils and humic substances demonstrated that with more intense management, both the intensities of the phenolic region (140–160 ppm) and the aromatic region (110–140 ppm) decreased. The combination of both independent methods MS and NMR, together with microbiological and biochemical data, yields the general result that intensive soil management leads to a less active humus.  相似文献   
7.
In order to evaluate the climatic and soil variables which control the denitrification processes in the field, measurements of N2O-losses using the C2H2 inhibition technique were carried out in an Inceptisol cropped with spring wheat. The silty sand was amended with mineral fertilizer (120 kg N ha?1) or additionally with sewage sludge (620 kg total N ha?1). Soil temperature, moisture, nitrate and available carbon, the release of nitrous oxide (N2O) from the soil surface as well as the N2O concentrations along the soil profile were measured from March until November 1985 The N2O surface fluxes from the inorganically fertilized field were well correlated with those from the sewage sludge amended plots (r = 0.76). Multivariate correlation analyses show that particularly soil moisture and nitrate content had a significant effect on the nitrate respiration. The correlation with the soil water content was more clearly expressed by the N2O surface fluxes than by the N2O concentrations of the soil air. The N2O surface fluxes during 1985 totalled about 3 kg N ha?1 in the minerally fertilized field. Sewage sludge amendments increased the N2O evolution by 5 times. Spatial variability was high and the N2O surface fluxes were not well correlated (r = 0.4) with the N2O concentrations in the soil atmosphere. These experiments provide the background data for a denitrification model and better knowledge about the variables which have to be considered for its validation.  相似文献   
8.
Three melanoid fungi, namely Alternaria alternata, Curvularia lunata and Drechslera australiensis were grown on 14C-glucose and then fractionated into cell wall, cytoplasm and melanin. The decomposition of these fractions and their contribution to the stable organic matter fraction was studied in a marginally sodic soil. The rate of decomposition of fungal melanins was less than that of the cell wall or cytoplasm which had the highest rate of decomposition. However, the contribution of these fractions to the humic acid fraction was very low. Most of the 14C-activity was recovered in the humin fraction.  相似文献   
9.
Catechol and chlorocatechols occur as intermediary metabolites during the degradation of naturally-occurring and synthetic aromatic compounds. Their degradation in soil was assessed under laboratory conditions using 14C-tracing techniques. Degradation of all compounds to CO2 was rapid during the first 2 weeks (5–10% week?1, but gradually decreased to below 1% week?1 after 3 months. After 6 months. 44% of 4,5-dichlorocatechol, 38% of 4-chloro- and tetrachlorocatechols, and 30% of catechol were degraded to CO2. In comparison, chlorophenols were degraded at similar rates, and chloroanilines were degraded more slowly. A mixed extradant of citric acid-ascorbic acid-acetone (1:1:2) was found to be most effective in extracting the catcchols from variously-treated soil samples. Recovery of added 14C from freshly fortified soils ranged from 74% for catechol to 98%, for tetrachlorocatechol. After equilibration of 14C-chemical with soil for 5–20 days, the extractability decreased to 38% for catechol, but remained over 86% for tetrachlorocatechol. Sterilization of soil before 14C addition had little effect on 14C extractability. After incubation of treated soil for 5 months, only 20–35% of residual 14C could be extracted. More than half of the nonextractable 14C-residues from incubated soil could be further removed by Na-pyrophosphate extraction.  相似文献   
10.
【目的】建立准确、无损的适宜于苹果不同品种和枝梢类型的叶面积估算模型。【方法】以富士及嘎啦不同长度的营养枝梢和果台枝梢叶片为试材,采用数字扫描仪获取叶片长度(LL)、宽度(LW)和叶面积(LA)等叶片形态参数,并采用决定系数(R2)、均方根误差(RMSE)、赤池信息准则(AIC)对建立的17个有常数项和无常数项叶面积模型精度进行筛选和适宜性评价。【结果】共获得5 207枚叶片形态参数,其中叶面积变异系数最大,达51.59%。叶片形态受品种及枝梢类型的显著影响,其中长枝梢叶片长、宽和叶面积显著大于同类型短枝梢叶片,而营养枝梢叶片长、宽和叶面积显著大于同长度果台枝梢,嘎啦叶片相比富士更为细长。以LL和LW复合变量为自变量的模型5:LA=a(LL×LW)、模型6:LA=a(LL+LW)2、模型9:LA=aLL2+bLW2、模型16:LA=a(LL×LW)b、模型17:LA=(LL×LW)b的精度可满足富士和嘎啦各类枝梢叶面积的估算,但需针对各品种和枝梢类型单独建...  相似文献   
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