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51.
《Computer Aided Geometric Design》2014,31(9):613-630
One major issue in CAGD is to model complex objects using free-form surfaces of general topology. A natural approach is curvenet-based design, where designers directly create and modify feature curves. These are interpolated by smoothly connected, multi-sided patches, which can be represented by transfinite surfaces, defined as a combination of side interpolants or ribbons. A ribbon embeds Hermite data, i.e., prescribed positional and cross-derivative functions along boundary curves.The paper focuses on two transfinite schemes: the first is an enhanced and extended variant of a multi-sided generalization of the classical Coons patch (Várady et al., 2011); the second one is based on a new concept of combining doubly curved composite ribbons, each one interpolating three adjacent sides. Main contributions include various ribbon parameterizations that surpass former methods in quality and computational efficiency. It is proven that these surfaces smoothly interpolate the prescribed ribbon data. Both formulations are based on non-regular convex polygonal domains and distance-based, rational blending functions. A few examples illustrate the results. 相似文献
52.
《Information Security Journal: A Global Perspective》2013,22(1):46-54
Abstract Biometrics can be defined as science by which an individual is identified through analyses of physical data and behavioral characteristics.1 The measurement of an individual's characteristics quantifies his or her physical, behavioral characteristics. The physically unique characteristics include, but are not limited to, fingerprints, hand or palm geometry, retina or iris scans, voice or facial characteristics, keystroke patterns, and gait. These presumably unique characteristics are used, in turn, to recognize (identify), authenticate, deny, or grant access based on the individual's characteristics. 相似文献
53.
Qiang Sang Jian‐Zhou Zhang 《International journal of imaging systems and technology》2013,23(4):338-345
An automatic method has been developed to interpolate between neighboring slices in a gray‐scale data set by anisotropic diffusion of feature point correspondence. The feature point extracted is registered to form the feature vector. Thus a three dimensional (3D) weight anisotropic vector diffusion is introduced to spread the feature vector to the correspondence vector, which estimates spatial correspondence between adjacent slices. Bilinear interpolation is made along the direction of correspondence vector. Experiments are performed on medical data sets to evaluate the proposed method, showing that the new algorithm achieves good quality and improvement in efficiency relative to the traditional methods. © 2013 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 23, 338–345, 2013 相似文献
54.
A. Benzaza 《International journal of control》2013,86(12):2784-2790
In this paper, we study the feedback stabilisation of homogeneous bilinear systems on a Banach state-space. Sufficient conditions for weak and strong stabilisation are given. A decay rate of the stabilised state is explicitly estimated. Applications to heat and transport equations are provided. 相似文献
55.
基于插值法建立乳制品中酪蛋白的核磁共振磷谱定量检测方法。结果表明,该方法的检出限为0.38 g/L(信噪比(RSN)=3),定量限为1.25 g/L(RSN=10);在5.00~35.00 g/L质量浓度范围内线性良好,相关系数R2大于0.999;加标回收率在91.94%~105.10%范围区间;日内精密度在0.65%~1.40%范围区间;日间精密度在1.40%~1.80%范围区间。对市售不同乳制品中酪蛋白含量进行检测,该方法与GB 31638—2016《酪蛋白》测定结果误差在±5%以内,满足方法可行性对比分析验证要求。该方法相比常规方法样品前处理简单、定量准确性高,大大缩短了检测时间,且有更广泛的适用性,满足乳制品中酪蛋白快速定量检测的要求。 相似文献
56.
针对区域地面沉降监测点数量有限、分布不均的情况,一般采用空间插值的手段建立表面拟合模型来解决。基于分形插值,采用随机选择迭代函数的思想对传统的趋势面拟合法作出改进,改进后拟合优度系数提高0.03,达到0.995,且改进前后的拟合结果符合显著性检验的要求。实验结果表明:改进前后趋势面拟合法拟合结果满足地面沉降监测的精度要求,改进后方法的拟合优度更高,对现实地面沉降量变化的描绘更加真实,可为沉降灾害评价工作提供更准确的依据。 相似文献
57.
To deal with uncertainty of the spectral distribution, we consider minimax interpolation and extrapolation problems in Lp for stationary processes. The interpolation and extrapolation problems can be regarded as a linear approximation problem on the unit disk in the complex plane. Although the robust one-step-ahead predictor and interpolator has already been considered separately in the previous literature, we give two conditions for the uncertainty class to find the minimax interpolator and extrapolator in the general framework from both the point of view of the observation set and the point of view of evaluation on the interpolation and extrapolation error under the Lp-norm. We show that there exists a minimax interpolator and extrapolator for the class of spectral densities ε-contaminated by unknown spectral densities under our conditions. When the uncertainty class contains spectral distribution functions which are not absolutely continuous to the Lebesgue measure, we show that there exists an approximate interpolator and extrapolator in Lp such that its maximal interpolation and extrapolation error is arbitrarily close to the minimax error when the spectral distributions have densities. Our results are applicable to the stationary harmonizable stable processes. 相似文献
58.
59.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
60.
Five-axis machining plays an important role in manufacturing by dint of its high efficiency and accuracy. While two rotation axes benefit the flexibility of machining, it also brings limitations and challenges. In order to further balance machining precision and efficiency, an improved feedrate scheduling method is presented considering geometric error and kinematic constraints for the Non Uniform Rational B-Spline (NURBS) interpolation in five-axis machining. A simplification method is proposed to calculate the geometric error which describes the deviation between the ideal tool path and the real tool path induced by the non-linear movement. A linear relation between geometric error and feedrate is built to limit the feedrate. The constraints determined by single axis kinematic performance and tangential kinematic performance are also considered. Under these constraints, a constrained feedrate profile is determined. Aiming to get more constant feedrate in the difficult-to-machine areas, this work proposes a scheduling method which combines morphological filtering and S-shape acceleration/deceleration (acc/dec) mode. Simulations and experiments are performed to compare the proposed feedrate scheduling method with two previous feedrate scheduling method and the results prove that the proposed feedrate scheduling method is reliable and effective. 相似文献