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排序方式: 共有655条查询结果,搜索用时 265 毫秒
81.
L. Vimala Devi S. Sellaiyan T. Selvalakshmi H.J. Zhang A. Uedono K. Sivaji S. Sankar 《Advanced Powder Technology》2017,28(11):3026-3038
Monoclinic undoped and Tb doped CuO are prepared by solution combustion method and annealed at different temperatures. The effect of annealing and doping on their structural and optical properties of CuO are examined using XRD, FTIR and DRS. The surface and lattice defects in CuO and Tb doped CuO is analyzed qualitatively and quantitatively using positron lifetime and Doppler broadening spectroscopy. The average positron lifetime and electron momentum (energy) S parameter increases owing to the number of vacancies in the CuO lattice upon doping and decreases with increasing temperature. The migration of vacancies from grain to grain boundary region is observed at 600 °C annealed samples. At 800 °C, the overall behavior of lifetime value denotes that the vacancy type defect is recovered, cluster vacancy and microvoids exists with reducing size. The photocatalytic performance of undoped and Tb doped CuO on degradation of methylene blue (MB) and methyl orange (MO) is investigated under visible light for two different lamp power and dye concentration. The influence of annealing temperature and dopant ion on the efficiency is also elaborated. Enhanced photocatalytic efficiency in Tb doped CuO is observed upon annealing. X-ray photoelectron spectroscopy (XPS) result indicates that the valence states of Cu, O and Tb ions exist at the surface of the particles. Brunauer–Emmett–Teller N2 adsorption–desorption analyses were employed to characterize specific surface area and porosity of Tb doped CuO. The doped CuO with pore size of about ~34 nm have a surface area of 16–28 m2/g. The surface area effect plays an important role in the enhanced catalytic performance on Tb doped catalysts. 相似文献
82.
Diabetes is associated with many complications that could lead to death. Diabetic retinopathy, a complication of diabetes, is difficult to diagnose and may lead to vision loss. Visual identification of micro features in fundus images for the diagnosis of DR is a complex and challenging task for clinicians. Because clinical testing involves complex procedures and is time-consuming, an automated system would help ophthalmologists to detect DR and administer treatment in a timely manner so that blindness can be avoided. Previous research works have focused on image processing algorithms, or neural networks, or signal processing techniques alone to detect diabetic retinopathy. Therefore, we aimed to develop a novel integrated approach to increase the accuracy of detection. This approach utilized both convolutional neural networks and signal processing techniques. In this proposed method, the biological electro retinogram (ERG) sensor network (BSN) and deep convolution neural network (DCNN) were developed to detect and classify DR. In the BSN system, electrodes were used to record ERG signal, which was pre-processed to be noise-free. Processing was performed in the frequency domain by the application of fast Fourier transform (FFT) and mel frequency cepstral coefficients (MFCCs) were extracted. Artificial neural network (ANN) classifier was used to classify the signals of eyes with DR and normal eye. Additionally, fundus images were captured using a fundus camera, and these were used as the input for DCNN-based analysis. The DCNN consisted of many layers to facilitate the extraction of features and classification of fundus images into normal images, non-proliferative DR (NPDR) or early-stage DR images, and proliferative DR (PDR) or advanced-stage DR images. Furthermore, it classified NPDR according to microaneurysms, hemorrhages, cotton wool spots, and exudates, and the presence of new blood vessels indicated PDR. The accuracy, sensitivity, and specificity of the ANN classifier were found to be 94%, 95%, and 93%, respectively. Both the accuracy rate and sensitivity rate of the DCNN classifier was 96.5% for the images acquired from various hospitals as well as databases. A comparison between the accuracy rates of BSN and DCNN approaches showed that DCNN with fundus images decreased the error rate to 4%. 相似文献
83.
Recommender system is a tool to suggest items to the users from the extensive history of the user's feedback. Though, it is an emerging research area concerning academics and industries, where it suffers from sparsity, scalability, and cold start problems. This paper addresses sparsity, and scalability problems of model-based collaborative recommender system based on ensemble learning approach and enhanced clustering algorithm for movie recommendations. In this paper, an effective movie recommendation system is proposed by Classification and Regression Tree (CART) algorithm, enhanced Balanced Iterative Reducing and Clustering using Hierarchies (BIRCH) algorithm and truncation method. In this research paper, a new hyper parameters tuning is added in BIRCH algorithm to enhance the cluster formation process, where the proposed algorithm is named as enhanced BIRCH. The proposed model yields quality movie recommendation to the new user using Gradient boost classification with broad coverage. In this paper, the proposed model is tested on Movielens dataset, and the performance is evaluated by means of Mean Absolute Error (MAE), precision, recall and f-measure. The experimental results showed the superiority of proposed model in movie recommendation compared to the existing models. The proposed model obtained 0.52 and 0.57 MAE value on Movielens 100k and 1M datasets. Further, the proposed model obtained 0.83 of precision, 0.86 of recall and 0.86 of f-measure on Movielens 100k dataset, which are effective compared to the existing models in movie recommendation. 相似文献
84.
Aruna Devi Balasubramanian Pallikonda Rajasekaran Murugan Arun Prasath Thiyagarajan 《International journal of imaging systems and technology》2019,29(4):399-418
Computer-aided diagnosis (CAD) is a computerized way of detecting tumors in MR images. Magnetic resonance imaging (MRI) has been generally used in the diagnosis and detection of pancreatic tumors. In a medical imaging system, soft tissue contrast and noninvasiveness are clear preferences of MRI. Inaccurate detection of tumor and long time consumption are the disadvantages of MRI. Computerized classifiers can greatly renew the diagnosis activity, in terms of both accuracy and time necessity by normal and abnormal images, automatically. This article presents an intelligent, automatic, accurate, and robust method to classify human pancreas MRI images as normal or abnormal in terms of pancreatic tumor. It represents the response of artificial neural network (ANN) and support vector machine (SVM) techniques for pancreatic tumor classification. For this, we extract features from MR images of pancreas using the GLCM method and select the best features using JAFER algorithm. These features are analyzed by five classification techniques: ANN BP, ANN RBF, SVM Linear, SVM Poly, and SVM RBF. We compare the results with benchmark data set of MR brain images. The analytical outcome presents that the two best features used to classify the MR images using ANN BP technique have 98% classification accuracy. 相似文献
85.
Devi Salam Shuleenda Roy Amarjit Singha Joyeeta Sheikh Shah Alam Laskar Rabul Hussain 《Multimedia Tools and Applications》2018,77(1):661-662
Multimedia Tools and Applications - 相似文献
86.
NCO‐terminated polyurethane membranes were prepared using diisocyanate, diol, and trimethylolpropane (TMP) using an NCO/OH ratio of 1.6 : 1. Prepolymer was chain‐extended using cellulose acetate butyrate (CAB) in the ratios of 2 : 1, 4 : 1, and 3 : 1 of NCO/OH. Polyurethane (PU) membranes were characterized by differential scanning calorimeter (DSC) and thermogravimetry (TGA) to investigate their thermal properties. Equilibrium sorption studies were carried out at 30°C in water and ethyl acetate media as well as in their binary mixtures. The influence of CAB on pervaporation (PV) separation of an ethyl acetate/water (92/8, w/w, i.e., azeotropic composition) mixture was investigated. Membranes in this study showed a selectivity of 42.42 with a flux value of 0.187 kg/m/h for 3 : 1% NCO/OH containing PU membrane. In order to gain a more detailed picture of the molecular transport phenomenon, we performed the sorption gravimetric experiments at 30°, 35°, 40°, and 50°C to compute diffusion, swelling, sorption, and permeability coefficients of PU membranes in the azeotropic mixture of ethyl acetate and water. Activation parameters for diffusion and permeation were computed from the Arrhenius equation to understand the polymer/solvent interactions. Sorption trends and diffusion anomalies were established through an empirical equation after estimating the diffusion parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3405–3414, 2007 相似文献
87.
Oligomeric Composition of Polyols From Fatty Acid Methyl Ester: The Effect of Ring‐Opening Reactants of Epoxide Groups 下载免费PDF全文
Tuan Noor Maznee Tuan Ismail Nor Azowa Ibrahim Mohd Azmil Mohd Noor Seng Soi Hoong Kosheela Devi Poo Palam Shoot Kian Yeong Zainab Idris Christi M. Schiffman Ibrahim Sendijarevic Emilia Abd Malek Norhazlin Zainuddin Vahid Sendijarevic 《Journal of the American Oil Chemists' Society》2018,95(4):509-523
Commercial availability of fatty acid methyl ester (FAME) from palm oil targeted for biodiesel offers a good feedstock for the production of structurally well‐defined polyols for polyurethane applications. The effect of molecular weight (MW), odd and even carbon numbers, and the linear and branched structure reactants used in the ring‐opening reaction of epoxidized fatty acid methyl ester (E‐FAME) on the properties of polyols was investigated. Conversions of E‐FAME to PolyFAME polyols were confirmed by Fourier transform infrared analysis, oxirane oxygen content, and hydroxyl number. Gel permeation chromatography (GPC) calibrated against polyether polyols as a standard and vapor pressure osmometry were used for MW determination. GPC chromatograms of PolyFAME polyols clearly demonstrated the formation of oligomers during ring‐opening reactions. MW, and odd and even carbon numbers in a structure of linear diols and branched diol used in the syntheses of PolyFAME polyols did not have an effect on crystallinity, glass transition, or melt temperatures measured using Differential scanning calorimetry (DSC). PolyFAME polyols ring‐opened with water, methanol, and 1,2‐propanediol contained secondary hydroxyl groups, whereas PolyFAME polyols ring‐opened with linear diols contained a mixture of primary and secondary hydroxyl groups. It was found that the concentration of primary hydroxyl groups increased significantly by increasing the number of carbons from C2 to C3 in the linear diols. The viscosity of PolyFAME polyols also increased with the MW of linear diols used in the E‐FAME ring‐opening reaction. These findings would be beneficial for formulators in choosing the most cost effective polyols for polyurethane formulations. 相似文献
88.
In the present study, an Enterococcus gallinarum strain was isolated from effluent treatment plant of a textile industry based on its ability to decolourize C.I. Direct Black 38 (DB38), a benzidine-based azo dye. Effects of dye concentration and medium composition on dye decolourization were studied. The strain was found to decolourize DB38 even under aerobic conditions. Kinetics of DB38 decolourization was also examined, and V(max) and K(s) of decolourization were found to be higher in Luria broth (12.8 mg l(-1)h(-1) and 490.6 mg l(-1)) than in minimal medium (4.09 mg l(-1)h(-1) and 161.84 mg l(-1)). However, decolourization rate/biomass was found to be higher in minimal medium than in Luria broth, indicating greater decolourization efficiency of biomass in the former. The study also revealed biodegradation of DB38 to benzidine and its further deamination to 4-aminobiphenyl (4-ABP) by the culture. Ammonia released during this process was used as nitrogen source for growth of the culture. 相似文献
89.
The present work discusses the combined effect of High Density Polyethylene Homo polymer and Styrene-Butadiene-Styrene on properties of Viscosity Grade 30 asphalt commonly used in India. Six blends of binders were prepared using varying percentages of both polymers and were evaluated for rheological properties. Use of both polymers leads to higher viscosity, while blending with HDPH polymer only leads to marginal increase in viscosity when compared to unmodified binder. Comparison of dynamic modulus and phase angle master curves indicated, significant differences were found among master curves obtained with different aging conditions when compared to unaged condition especially at lower reduced frequencies. 相似文献
90.
S Sailaja Devi M Radhakrishna Reddy P Sambasiva Reddy K Hussain Reddy K Mohana Raju 《Polymer International》2000,49(11):1338-1342
A series of polymer supported cobalt complexes have been synthesized by the reaction of Co(II)‐SALEN (salicylaldehyde ethylenediimine) and other variations thereof with the chelating resin containing vinyl pyridine. The polymer supported complexes have been characterized by electronic and infrared spectra. The presence of polymer supports has a marked influence on the UV–visible bands observed in the electronic spectra of cobalt complexes. These polymer supported complexes are also investigated by cyclic voltammetry. The electronic spectral data and cyclic voltammetric data for free complexes and polymer supported complexes are compared. The discernible differences in the spectral and electrochemical data suggest the presence of pentacoordinate cobalt in the polymer matrix. © 2000 Society of Chemical Industry 相似文献