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1.
目的 为了解决目前消色算法中不能同时保持原始图像的对比度,颜色一致性和灰度像素特征的问题,提出一种新的优化算法,最大限度地同时保留这些视觉特性。方法 为了保持原始图像的结构和局部对比度信息,用双高斯模型构建像素对之间的误差能量项;为了保持颜色一致性,采用局部线性嵌入模型构建能量项,确保原始图像中颜色一致的像素在结果图像中也拥有一样的灰度级;为了保持灰度像素特征,先标记出原始图像中的灰度像素,并强制规定这些像素的灰度值是已知的且在消色变换的过程中始终不变,然后用双高斯模型构建出灰度像素与其他像素之间的误差能量项。线性结合这3个能量项,得到目标能量函数,再通过迭代法求解出使总能量值达到最小的灰度值,从而得到了最终的消色结果。结果 实验结果表明,本文算法能够同时较好地保持原始图像中的对比度、颜色一致性和灰度像素特征。结论 本文算法基本符合人类对图像对比度变化的感知程度,而且能够很好地保持细节信息和全局结构,可应用于数字打印、模式识别等方面,具有很大的应用价值。  相似文献   
2.
Reversible contrast mapping (RCM) and its various modified versions are used extensively in reversible watermarking (RW) to embed secret information into the digital contents. RCM based RW accomplishes a simple integer transform applied on pair of pixels and their least significant bits (LSB) are used for data embedding. It is perfectly invertible even if the LSBs of the transformed pixels are lost during data embedding. RCM offers high embedding rate at relatively low visual distortion (embedding distortion). Moreover, low computation cost and ease of hardware realization make it attractive for real-time implementation. To this aim, this paper proposes a field programmable gate array (FPGA) based very large scale integration (VLSI) architecture of RCM-RW algorithm for digital images that can serve the purpose of media authentication in real-time environment. Two architectures, one for block size (8 × 8) and the other one for (32 × 32) block are developed. The proposed architecture allows a 6-stage pipelining technique to speed up the circuit operation. For a cover image of block size (32 × 32), the proposed architecture requires 9881 slices, 9347 slice flip-flops, 11291 number 4-input LUTs, 3 BRAMs and a data rate of 1.0395 Mbps at an operating frequency as high as 98.76 MHz.  相似文献   
3.
Preliminary results illustrate the possibility of charge contrast imaging (CCI) of polymeric materials. Possible CCI images of low-density polyethylene and polyvinyl chloride reveal details that may aid in the characterization of the microstructure of polymeric materials. These pictures were obtained with a Hitachi S-3000N variable pressure scanning electron microscope with the environmental secondary electron detector (ESED).  相似文献   
4.
地区洪峰流量模比系数综合频率曲线法是规范允许的资料短缺地区使用的方法,能够反映地区洪峰流量模比系数的综合规律。该方法能充分利用水库坝址处的历史洪水调查结果,计算成果相对合理。水文比拟法是解决无资料或缺少资料的小流域设计洪水计算问题简单实用的方法之一,在该计算方法中流域面积具有十分重要的作用,对计算成果会产生较大的影响。  相似文献   
5.
Based on column approximation (CA) assumption, many-beam Schaeublin–Stadelmann diffraction equations are employed for simulating the transmission electron microscopy (TEM) diffraction image contrast of dislocation loops within thin TEM foil of finite thickness, and two beam and many beam diffraction conditions are compared. Moreover, the effects of materials anisotropy and free surface relaxation induced elastic fields distortion of dislocation loops on the black-white image contrast are specially focused. It is found that anisotropy has a remarkable impact on the TEM image contrast of dislocation loop, and free surface relaxation induced image forces can change the black-white contrast features when dislocation loops are near TEM foil free surfaces. Thus, in order to make reliable judgment on the nature of defects, effects of free surface and anisotropy should be included when analysing irradiation induced dislocation loops and other type of defects in in-situ electron, proton, heavy-ion irradiation experiments under TEM environments.  相似文献   
6.
The numbers of diagnosed patients by melanoma are drastic and contribute more deaths annually among young peoples. An approximately 192,310 new cases of skin cancer are diagnosed in 2019, which shows the importance of automated systems for the diagnosis process. Accordingly, this article presents an automated method for skin lesions detection and recognition using pixel‐based seed segmented images fusion and multilevel features reduction. The proposed method involves four key steps: (a) mean‐based function is implemented and fed input to top‐hat and bottom‐hat filters which later fused for contrast stretching, (b) seed region growing and graph‐cut method‐based lesion segmentation and fused both segmented lesions through pixel‐based fusion, (c) multilevel features such as histogram oriented gradient (HOG), speeded up robust features (SURF), and color are extracted and simple concatenation is performed, and (d) finally variance precise entropy‐based features reduction and classification through SVM via cubic kernel function. Two different experiments are performed for the evaluation of this method. The segmentation performance is evaluated on PH2, ISBI2016, and ISIC2017 with an accuracy of 95.86, 94.79, and 94.92%, respectively. The classification performance is evaluated on PH2 and ISBI2016 dataset with an accuracy of 98.20 and 95.42%, respectively. The results of the proposed automated systems are outstanding as compared to the current techniques reported in state of art, which demonstrate the validity of the proposed method.  相似文献   
7.
A novel differential interference contrast microscope (DICM) is proposed in this research. It is constituted by inserting a Savart shear prism between the objective and sample of a polarising microscope having a rotatable analyser as the phase‐shifter, and it is with the ability to enhance image contrast using the principle of shearing interferometry. This letter is to introduce the configuration, interpret the interference patterns and present the experimental setup of the DICM. In addition, this letter is to display the experimental results from the uses of the setup; the results demonstrate the validity and ability of the DICM.  相似文献   
8.
M. LIU 《Journal of microscopy》2018,269(3):221-229
Differential interference contrast‐photothermal microscopy (DIC‐PTM), as a promising tool for trace analysis of nonfluorescent compounds, suffered low sensitivity in nanospace especially for aqueous samples, due to the poor thermophysical property of water and the unoptimised configuration. To improve its performance, a five‐layer DIC‐PTM model is built and influences of different parameters on the photothermal signal are investigated. The initial phase shift φ0 between two branches of the probe beam is found to be a key factor determining the detection sensitivity and response linearity: at a large φ0 (≤π/2) both a high sensitivity and a good linearity can be achieved, while a high signal‐to‐noise ratio occurs at a small φ0. The steady‐state photothermal phase shift φdc has little impact on the linearity, which, however, is greatly influenced by the range of periodic photothermal phase shift φac. By introducing two coatings into a nanospace to confine the photothermal effect within and around the sample, the sensitivity can be enhanced from a few times to over 100 times. On an optimised DIC‐PTM configuration and chip structure, detection limit down to 10?3 cm?1 (or 40 molecules in a detection volume of 0.2 fL) was achieved in a 300‐nm‐thick nanospace. This work paves a way for optimising the DIC‐PTM and chip structure for sensitive detection of analytes in nanospaces.  相似文献   
9.
Epithelial cell dynamics can be difficult to study in intact animals or tissues. Here we use the medusa form of the hydrozoan Clytia hemisphaerica, which is covered with a monolayer of epithelial cells, to test the efficacy of an orientation‐independent differential interference contrast microscope for in vivo imaging of wound healing. Orientation‐independent differential interference contrast provides an unprecedented resolution phase image of epithelial cells closing a wound in a live, nontransgenic animal model. In particular, the orientation‐independent differential interference contrast microscope equipped with a 40x/0.75NA objective lens and using the illumination light with wavelength 546 nm demonstrated a resolution of 460 nm. The repair of individual cells, the adhesion of cells to close a gap, and the concomitant contraction of these cells during closure is clearly visualized.  相似文献   
10.
郭凌华  王晶  孙栗媛  温蕾  党玲玉 《包装工程》2018,39(15):210-215
目的从相对反差最大时密度最佳的角度出发,结合网点扩大,构建基于回归算法的数学模型,确定最佳的实地密度,从而提高印刷品的质量。方法获取过版样张,根据测量的实地密度、相对反差和网点扩大值作出三维坐标图,并基于回归算法建立相对反差K、网点扩大与实地密度函数关系的数学模型;利用该模型找到相对反差最大时,网点扩大和实地密度的参数匹配算法;网点扩大在国标范围(15%~20%)内,最终以方差最小原则确定最佳的实地密度。结果基于回归算法找到了当相对反差最大时实地密度和网点扩大的参数匹配符合函数y=ax+b,确定了C,M,Y,BK油墨的最佳实地密度分别为1.551,1.612,0.975,1.828。结论基于回归算法确定最佳实地密度的方法能够保证相对反差良好,网点扩大适宜,提高了印刷品的清晰度和鲜艳程度,对印刷的质量控制具有一定的指导意义。  相似文献   
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