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排序方式: 共有193条查询结果,搜索用时 15 毫秒
71.
基于近红外光谱的番茄黄化曲叶病抗病性识别研究   总被引:1,自引:0,他引:1  
使用传统的聚合酶链反应技术检测番茄(Lycopersicon esculentum Mill.)植株是否有黄化曲叶病的抗病基因,进而确定植株是否具有抗病性;采集鉴定后的植株叶片的近红外漫反射光谱,采用多种方法对原始光谱进行预处理,并将不同预处理后的数据以及原始光谱作为输入,利用支持向量机建立抗病性的识别模型。采用标准正态变量变换和去趋势算法预处理后所建立的模型对预测集的识别准确率可以达到96.153 8%。表明通过近红外光谱技术可以识别番茄植株对黄化曲叶病是否具有抗病性。  相似文献   
72.
为探索不同烘烤条件下烤烟纤维素含量近红外光谱检测模型,采用偏最小二乘回归法(PLS)对不同烘烤条件下的共85个样品,分别基于全部波长建立模型。常规烘烤时,定标集r=0.9949,RMSE=0.1122;交叉验证集r=0.9234,RMSE=0.4636;预测集r=0.8982,RMSE=0.6963。低温烘烤时,定标集r=0.9811,RMSE=0.3279;交叉验证集r=0.9456,RMSE=0.5290;预测集r=0.9938,RMSE=0.1608。高温烘烤时,定标集r=0.9128,RMSE=0.4381;交叉验证集r=0.8215,RMSE=0.6162;预测集r=0.9743,RMSE=0.1986。结果表明,采用偏最小二乘法预测不同烘烤条件下烤烟纤维素含量是可行的。  相似文献   
73.
The aim of this work was to assess the effect of the presence of ash on maximum temperature reached (MTR) estimation using near infrared reflectance (NIR) spectroscopy. The degree of combustion (ash produced by heating to 100, 300, 500 and 700 °C), the type (ash from Pinus halepensis and Rosmarinus officinalis), and different quantities of ash (0–20% in 2% interval) were evaluated in a soil heated at seven different temperatures (100 °C–700 °C). Results showed that the estimation of MTR on samples with ash, using partial least squares (PLS) models constructed with samples without ash, could be erroneous. Both, ash quantity and degree of combustion affected the estimation of MTR. However, using discriminant analysis, a good classification of samples (> 97% correctly classified) according to the heating temperature classes (unheated, 100, 200, 300, 400, 500, 600 and 700 °C) was obtained despite the presence of ash.  相似文献   
74.
NIR spectroscopy presents a huge interest in exploring chemical changes during dough mixing. The aim of the present study is to investigate the potential of 2D correlation spectroscopy (2D COS) and moving-window 2D (MW2D) correlation spectroscopy to explore the time dependence of NIR spectral responses during wheat flour dough mixing. NIR spectra were continuously recorded (between 1400 and 2325 nm) during mixing of bread type-dough (based on flour, water and yeast), using an FT-NIR spectrometer with a deported probe. The probe was positioned inside the mixer in contact with the dough. The 2D spectra calculated using raw and second derivative NIR spectra were interpreted in terms of physico-chemical events. Nine different industrial flours were used as raw material to validate the analysis. The results obtained using the 2D COS and the MW2D methods give the possibility to ascribe chemical vibrations (starch, water and gluten) to NIR absorbance changes occurring during dough mixing. The analysis of the NIR spectra identified wavelength shift associated to both dough “free water” and protein secondary structure modifications. During this study, only the MW2D method allowed to identify clearly the time dependence of physico-chemical mechanisms from NIR variation bands.  相似文献   
75.
Maize is the main crop cultivated worldwide with more than 1 billion metric tons produced annually and is one of the most relevant sources of protein for human consumption in developing countries. Proteins and peptides isolated from maize exert relevant antioxidant activity which is increased by enzymatic hydrolysis. However, there is limited information about the antioxidant potential of proteins isolated from Quality Protein Maize (QPM) varieties and their hydrolysates. The aim of this research was to determine the differences in protein profile and antioxidant activity of protein fractions and hydrolysates between a hybrid white maize (Asgrow 773) and a QPM variety (CML-502). The biophysical evaluation and the total protein quantification by Kjeldahl and fractions by ninhydrin were consistent with the changes due to the breeding process of the QPM material. The antioxidant potential of the hydrolysates obtained from albumins and globulins had a 3-fold increase in both maize varieties. The prolamins hydrolysates presented an increase of 7-fold for the normal variety and 2-fold for the QPM variety. The results of this research allow indicate that the QPM varieties are a source of antioxidant peptides and promising candidates in the search for proteins and peptides with other bioactivities.  相似文献   
76.
77.
近红外光谱法无损检测番茄可溶性固形物含量的研究   总被引:2,自引:0,他引:2  
应用近红外漫反射光谱技术对番茄可溶性固形物含量进行了非破坏性检测分析,比较了10种不同的光谱预处理方法对偏最小二乘法(PLS)模型的影响.结果表明,常数偏移消除是适合建立近红外光谱法无损检测番茄可溶性固形物含量PLS模型的最优光谱预处理方法,最能反映番茄可溶性固形物含量信息的光谱波段为11998.9-5449.8cm-1和4601.3~4246.5 cm-1.用偏最小二乘法建立的定量分析模型,其预测值和实测值的相关系数为0.954,校正标准差为0.321%,预测标准差为0.475%.近红外漫反射光谱法可非破坏性分析番茄中可溶性固形物的含量.  相似文献   
78.
现代近红外光谱技术——人造板性能无损检测的新方法   总被引:5,自引:1,他引:4  
文中介绍了现代近红外光谱技术原理、测试步骤、技术特点及在人造板性能测试中的技术及初步应用。  相似文献   
79.
氮磷钾对甜菜硝酸还原酶与亚硝酸还原酶的影响   总被引:1,自引:0,他引:1  
以当前甜菜生产主栽品种KWS0143为试材,采用"3414"试验设计,探讨了氮磷钾肥对甜菜硝酸还原酶和亚硝酸还原酶活性的影响,及2种酶活性与甜菜产、质量的关系。结果表明,在甜菜生育期间,2种酶活性基本呈双峰曲线变化;随着施氮水平的升高,酶活性增强;磷肥与酶活性在生育中期呈显著或极显著正相关关系;硝酸还原酶活性在甜菜生育中前期、后期与产量、产糖量表现显著或极显著正相关关系,亚硝酸还原酶活性在甜菜生育中期与产量、产糖量正相关关系达到极显著水平。酶活性与含糖率则一直保持着负相关关系。  相似文献   
80.
The usefulness of classifying the Alpaca wool samples according to their color, sex and location is associated with their economic value in the market, hence adequate methods for rapid classification are needed to assess the of wool value. This study evaluated the potential of the visible and near infrared (vis–NIR) spectroscopy combined with multivariate statistical analysis to classify Alpaca (Lama Pacos) fiber samples according to age (1 and 2–3-year-old), sex (Male and Female) and color (Black, Brown, LF and White). Samples (n = 291) were scanned in reflectance mode in the wavelength range of 400–2500 nm using a monochromator instrument (FOSS NIRSystems6500, Inc., Silver Spring, MD, USA). Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to classify fiber samples. Cross-validation was used for validation of classification models developed. Results showed that PLS-DA correctly classified 100% of fiber samples into ages, intermediate classification rates were obtained for color, while lower classification rates were obtained for the discrimination of wool samples according to sex. The results from this study suggested that vis–NIR spectroscopy in combination with multivariate data analysis can be used as a rapid method to classify Alpaca fiber samples according to age, sex and color.  相似文献   
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