全文获取类型
收费全文 | 37135篇 |
免费 | 4303篇 |
国内免费 | 2491篇 |
学科分类
工业技术 | 43929篇 |
出版年
2024年 | 156篇 |
2023年 | 649篇 |
2022年 | 1473篇 |
2021年 | 1869篇 |
2020年 | 1487篇 |
2019年 | 1091篇 |
2018年 | 1265篇 |
2017年 | 1432篇 |
2016年 | 1304篇 |
2015年 | 2135篇 |
2014年 | 2504篇 |
2013年 | 2750篇 |
2012年 | 3179篇 |
2011年 | 3328篇 |
2010年 | 2876篇 |
2009年 | 2600篇 |
2008年 | 2543篇 |
2007年 | 2304篇 |
2006年 | 2123篇 |
2005年 | 1691篇 |
2004年 | 1247篇 |
2003年 | 786篇 |
2002年 | 693篇 |
2001年 | 557篇 |
2000年 | 481篇 |
1999年 | 320篇 |
1998年 | 205篇 |
1997年 | 158篇 |
1996年 | 158篇 |
1995年 | 125篇 |
1994年 | 81篇 |
1993年 | 69篇 |
1992年 | 76篇 |
1991年 | 50篇 |
1990年 | 34篇 |
1989年 | 44篇 |
1988年 | 18篇 |
1987年 | 11篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1977年 | 1篇 |
1966年 | 1篇 |
1959年 | 6篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
12.
13.
Kang Zhang Rong‐rong Wang Kai‐rui Zhang Fei Cheng Yu Tian Yi Lin Mi Zhou Pu‐xin Zhu 《Polymer International》2020,69(3):274-279
A series of hyperbranched poly(citric polyethylene glycol) (PCPEG) materials with varied polyethylene glycol (PEG) chain lengths as plasticizers were mixed with maize starch (MS) via cooking and film‐forming. The structure, pasting property, plasticization, aging property, moisture absorption and compatibility of plasticized starches were studied by means of Fourier transform infrared spectroscopy, X‐ray diffraction, rapid viscosity analysis, tension testing, moisture absorption measurements and scanning electron microscopy. Compared with PEG and citric acid, PCPEG was more effective in promoting starch chain movement and inhibiting the retrogradation of starch film. Also, PCPEG/MS had smaller moisture content. The longer the plasticizer chain, the better were the aging resistance and moisture resistance of starch. But with an increase of PEG chain length, mechanical properties of PCPEG/MS deteriorated and the compatibility between PCPEG and MS decreased. The hyperbranched derivative of PEG with longer chain exhibited improved plasticization and compatibility with starch. © 2019 Society of Chemical Industry 相似文献
15.
Bin Zhang Xuesong Jiang Fei Shen Xueming He Yong Fang Qiuhui Hu 《International Journal of Food Science & Technology》2021,56(6):2588-2595
This work intends to develop an online experimental system for screening of deoxynivalenol (DON) contamination in whole wheat meals by visible/near-infrared (Vis/NIR) spectroscopy and computer vision coupling technology. Spectral and image information of samples with various DON levels was collected at speed of 0.15 m s−1 on a conveyor belt. The two-type data were then integrated and subjected to chemometric analysis. Discriminant analysis showed that samples could be classified by setting 1000 μg kg−1 as the cut-off value. The best correct classified rate obtained in prediction was 93.55% based on fusion of spectral and image features, with reduced prediction uncertainty as compared to single feature. However, quantification of DON by quantitative analysis was not successful due to poor model performance. These results indicate that, although not accurate enough to provide conclusive result, this coupling technology could be adopted for rapid screening of DON contamination in cereals and feeds during processing. 相似文献
16.
17.
为提高稀疏表示跟踪模型性能,提出一种分段加权的反向稀疏跟踪算法,将跟踪问题转化为在贝叶斯框架下寻找概率最高的候选对象问题,构造不同的分段权重函数来分别度量候选目标与正负模板的判别特征系数。通过池化来降低跟踪结果的不确定性干扰,选择正负模板加权系数差值最大的候选表示作为跟踪结果。实验表明,在光照变化、遮挡、快速运动、运动模糊情况下,所提出的算法可以确保跟踪结果的准确性和鲁棒性。 相似文献
18.
19.
Xiao-Guang Yue Guang Zhang Qu Wu Fei Li Xian-Feng Chen Gao-Feng Ren Mei Li 《稀有金属(英文版)》2015,(2):125-132
In order to predict the wearing of stellite alloys,the related methods of rare metals data processing were discussed. The method of opposite degree(OD) algorithm was put forward to predict the wearing of stellite alloys.OD algorithm is based on prior numerical data, posterior numerical data and the opposite degree between numerical forecast data. To compare the performance of predicted results based on different algorithms, the back propagation(BP) and radial basis function(RBF) neural network methods were introduced. Predicted results show that the relative error of OD algorithm is smaller than those of BP and RBF neural network methods. OD algorithm is an effective method to predict the wearing of stellite alloys and it can be applied in practice. 相似文献
20.
Shengyue Gu Shouyang Zhang Fei Liu Wei Li 《Journal of the European Ceramic Society》2018,38(15):5082-5091
Y2Hf2O7 possesses low thermal conductivity and high melting point, which make it promising for a new anti-ablation material. For evaluating the thermal stability and the potential applications of Y2Hf2O7 on anti-ablation protection of C/C composites, Y2Hf2O7 ceramic powder was synthesized by solution combustion method and Y2Hf2O7 coating was prepared on the surface of SiC coated C/C composites using SAPS. Results shown that the coating exhibits good ablation resistance under the heat flux of 2.4?MW/m2 with the linear and mass ablation rates are 0.16?μm?s?1 and ?0.028?mg?s?1, respectively, after ablation for 40?s. With the prolonging of the ablation time, the increasing thermal stress causes the increase of cracks. Moreover, the chemical erosion from SiO2 and the physical volatilization of low temperature molten products aggravate failure of the Y2Hf2O7 coating. 相似文献