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991.
张磊 《特种铸造及有色合金》2007,27(9):725-727
研究了在重力自蔓延法制备陶瓷内衬复合钢管过程中在复合热管底部出现的多孔层现象,以及各类添加剂对其的影响,分析了多孔层出现的原因,探讨了抑制措施。试验结果表明,SiO2的存在是产生多孔层的主要原因,并且多孔层部分随着SiO2含量的增加而增加,助燃剂也能导致多孔层的出现。当SiO2的质量分数小于2%时,适量加入氟化物,可以有效减少多孔层的体积。 相似文献
992.
在影响粘土砂旧砂再生效果的诸多因素中,旧砂中水分含量是最重要的因素。本文就水分含量对再生效果的影响规律、再生效果最佳的水分含量等进行了研究和分析,得出了如下结论:并非含水量越低再生效果就越好,而是存在一个去泥率低谷区;再生效果最佳的适宜水分含量为1~2%。 相似文献
993.
根据炉渣结构的共存理论和相图,推导了CaOB2O3和FeOFe2O3B2O3渣系的热力学计算模型。结果表明:(1)理论计算的CaOB2O3渣系的作用浓度NCaO及NB2O3与实测的活度aCaO及aB2O3一致;(2)理论计算的FeOFe2O3B2O3渣系的氧化能力NFetO与实测的炉渣FetO的活度值相符合。这说明本文提出的热力学计算模型是合理的。 相似文献
994.
This paper is concerned with the existence and exponential stability of anti-periodic solutions of bidirectional associative memory (BAM) neural networks with multiple delays. Applying inequality techniques and Lyapunov method, Sufficient conditions which ensure the existence and exponential stability of anti-periodic solutions of the BAM neural networks are presented. Our results are new and supplement some previously known ones. 相似文献
995.
996.
Atmospheric water vapour content (WVC) is a vital parameter in the study of climate change. Various methods have been developed to derive atmospheric WVC from remotely sensed data. In this study, we compared three methods for retrieving atmospheric WVC from thermal infrared data in the Meteosat Second Generation-SEVIRI channels 9 (10.8 μm) and 10 (12.0 ?m). The three methods are (1) the split-window covariance-variance ratio method using a spatial moving window (method 1); (2) the split-window covariance-variance ratio method using a temporal moving window (method 2); and (3) the varying surface temperature method using split-window channel data (method 3). The derived WVC using these three methods was compared to two WVC data sets from European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data and the MODIS WVC product. Compared with these two data sets, the derived WVC using method 1 performed proved optimal. The valid pixels using methods 1 and 2 are greater than those using method 3. Furthermore, method 2 can be used to retrieve WVC over pixels where method 1 is invalid. 相似文献
997.
Yong Lin Xiaoping Xin Hongbin Zhang Xu Wang 《International journal of remote sensing》2015,36(19-20):5031-5044
Ecological time series data are widely used in ecological research thanks to the development of remote-sensing technologies and fixed ecological research stations. However, the serial correlation issue with time series, which violates the fundamental assumption of independence for traditional statistical models or analysis, is rarely considered by ecologists in vegetation–climate relationship research. In addition, the issue of time lags between climate change and vegetation response is also often ignored. Inadequate consideration of these issues produces misleading results in some cases. In this article, we propose an approach based on the Autoregressive Integrated Moving Average (ARIMA) model and the nonparametric test to address serial correlation issue and distribution requirements for the valid statistical analysis of time series data. With Hulunber meadow steppe as a case, we applied this approach to analyse the role of climate factors in vegetation dynamics based on leaf area index (LAI) data and climatic data. The results showed that the LAI dynamics of Hulunber meadow steppe were mainly related to temperature with the time lag of zero, whereas the impact of precipitation on LAI dynamics was not statistically obvious. The comparison of regression models that deal with serial correlation and residual normality to different extents showed that ignoring the serial correlation issue with time series data likely produces misleading results, highlighting the importance of serial correlation removal. The combination of nonparametric correlation tests with ARIMA-based cross-correlation analysis also proved quite useful in reducing the chance of spurious correlation and time lags resulting from outlier values in ARIMA-based cross-correlation. 相似文献
998.
Hadar Averbuch‐Elor Yunhai Wang Yiming Qian Minglun Gong Johannes Kopf Hao Zhang Daniel Cohen‐Or 《Computer Graphics Forum》2015,34(2):131-142
We present a distillation algorithm which operates on a large, unstructured, and noisy collection of internet images returned from an online object query. We introduce the notion of a distilled set, which is a clean, coherent, and structured subset of inlier images. In addition, the object of interest is properly segmented out throughout the distilled set. Our approach is unsupervised, built on a novel clustering scheme, and solves the distillation and object segmentation problems simultaneously. In essence, instead of distilling the collection of images, we distill a collection of loosely cutout foreground “shapes”, which may or may not contain the queried object. Our key observation, which motivated our clustering scheme, is that outlier shapes are expected to be random in nature, whereas, inlier shapes, which do tightly enclose the object of interest, tend to be well supported by similar shapes captured in similar views. We analyze the commonalities among candidate foreground segments, without aiming to analyze their semantics, but simply by clustering similar shapes and considering only the most significant clusters representing non‐trivial shapes. We show that when tuned conservatively, our distillation algorithm is able to extract a near perfect subset of true inliers. Furthermore, we show that our technique scales well in the sense that the precision rate remains high, as the collection grows. We demonstrate the utility of our distillation results with a number of interesting graphics applications. 相似文献
999.
1000.