全文获取类型
收费全文 | 1683篇 |
免费 | 186篇 |
国内免费 | 139篇 |
专业分类
电工技术 | 36篇 |
技术理论 | 1篇 |
综合类 | 91篇 |
化学工业 | 332篇 |
金属工艺 | 65篇 |
机械仪表 | 104篇 |
建筑科学 | 129篇 |
矿业工程 | 68篇 |
能源动力 | 51篇 |
轻工业 | 285篇 |
水利工程 | 16篇 |
石油天然气 | 16篇 |
武器工业 | 6篇 |
无线电 | 192篇 |
一般工业技术 | 182篇 |
冶金工业 | 15篇 |
原子能技术 | 11篇 |
自动化技术 | 408篇 |
出版年
2024年 | 6篇 |
2023年 | 116篇 |
2022年 | 93篇 |
2021年 | 84篇 |
2020年 | 77篇 |
2019年 | 57篇 |
2018年 | 43篇 |
2017年 | 59篇 |
2016年 | 43篇 |
2015年 | 55篇 |
2014年 | 102篇 |
2013年 | 113篇 |
2012年 | 218篇 |
2011年 | 207篇 |
2010年 | 104篇 |
2009年 | 107篇 |
2008年 | 84篇 |
2007年 | 147篇 |
2006年 | 106篇 |
2005年 | 51篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 17篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1980年 | 4篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有2008条查询结果,搜索用时 15 毫秒
1.
Energy resources are an important material foundation for the survival and development of human society, and the relationship between energy and economy is interactive and complementary. This paper analyzes the energy consumption–economic growth nexus in Chinese provinces using novel and recent nonparametric time-series as well as panel data empirical approaches. The dataset covers 30 provinces over the period of 1980–2018. The empirical analysis indicates the presence of a nonlinear functional form and smooth structural changes in most of the provinces. The nonparametric empirical analysis validates the presence of a nonlinear unit root problem in energy consumption and economic growth, and nonlinear cointegration between the variables. Additionally, the nonparametric panel cointegration test reports evidence of convergence in energy consumption and economic growth patterns across the provinces. The nonparametric regression analysis finds economic growth to have a positive effect, on average, on energy consumption in all provinces, except for Beijing. Further, the energy environmental Kuznets curve exists between economic growth and energy consumption in 20 out of 30 Chinese provinces. The Granger causality analysis reveals the presence of a mixed causal relationship between economic growth and energy consumption. The empirical findings have important implications for Chinese authorities in planning for improving energy efficiency, decoupling between economic growth and energy consumption, and reducing the environmental footprint of provinces. 相似文献
2.
《Applied catalysis. B, Environmental》2005,55(2):123-132
The photocatalytic oxidation of resorcinol, a potent endocrine disrupting chemical, in oxygenated aqueous suspensions of pure and cupric ions modified Degussa P25 titanium dioxide has been investigated at pH 3.0 ± 0.5. The initial rate of photocatalytic oxidation of resorcinol increased until an optimum dissolved cupric ions concentration was reached at 1.04 mM. At the optimum concentration of cupric ions, the initial rate of photocatalytic mineralisation and degradation of resorcinol was improved by 400%. The observed beneficial effect of cupric ions on the initial rate of resorcinol oxidation could be attributed to the formation of complex and its participation in the photoredox cyclic reaction.Two of the initial oxidation intermediates detected were 1,2,3-trihydroxybenzene and 1,2,4-trihydroxybenzene. These intermediates were formed via hydroxylation of the aromatic ring of resorcinol. Evidences have revealed that 1,2,4-trihydroxybenzene interacted strongly with cupric ions forming copper(II)-trihydroxybenzoate complexes that possessed good adsorption onto TiO2 surface. These dual-effects help to draw the metal ions closer to the photocatalyst surface and subsequently trigger the electron trapping mechanism by cupric ions. As a result, this improved the charge carriers’ separation. Furthermore, in the presence of oxygen, reoxidation of photoreduced cupric ions occurred and this eliminated the possibility of copper photodeposition, while inducing a photoredox cyclic reaction to regenerate copper species that may potentially act as co-catalyst for the oxidation of 1,2,4-trihydroxybenzene. In contrast, no obvious complex formation was seen between 1,2,3-trihydroxybenzene and cupric ions. This pointed to an intriguing finding which indicates that the positioning of functional group on benzene ring influences the role of cupric ions. 相似文献
3.
光照一致性是增强现实中实现虚实融合的重要方面,实时地估计出户外场景中的光照方向,对实现户外场景光照一致性和增强真实感具有重要意义.针对光照方向估计问题,首先归纳了户外场景光照方向估计的特点,把现有的光照方向估计方法分为借助光测球等特殊标定物的估算方法、立体视觉法和人工智能法3类方法.然后总结了各类方法的基本原理和有代表性的研究工作,并且比较了各类方法的优缺点和适用范围.最后,根据实际应用中存在的问题和挑战,展望了户外增强现实系统光照方向估计的研究方向. 相似文献
4.
针对块对角表示(block diagonal representation, BDR)子空间聚类算法在对子空间重叠的高维数据聚类时效果较差的问题,提出成对约束的块对角子空间聚类(constrained subspace clustering with block diagonal representation, CBDR)算法,设计主动式学习策略,获取用户提供的少量数据点成对信息,以改进BDR算法的性能,给出CBDR算法的目标函数和求解过程。在测试集上的试验结果表明,CBDR算法的聚类错误率和归一化互信息指标比BDR和SBDR(structured block diagonal representation)算法好,而且主动式选取点对方法优于随机选取点对方法,使用少于5‰的约束信息可降低BDR的聚类错误率达到5%以上。 相似文献
5.
Silicon - Hollow glass microsphere (HGM)/silicone rubber composite material was prepared by using silicone resin as the transition layer between silicone rubber and HGM. Silane coupling agent was... 相似文献
6.
7.
为使学生能深刻理解电路分析方法,调动学生学习的积极性,提高教学质量,将Matlab/Simulink这个工具应用于电路分析的教学过程中。具体以直流稳态电路分析、线性动态电路的时域分析、线性动态电路复频域分析为例,通过建模、Matlab编程、Simulink仿真对电路进行分析。阐述了Matlab/Simulink工具的应用特点:利用Matlab矩阵运算能力,可以解电路方程;利用图形函数,可以得到简明、生动的图形;Matlab中的Simulink工具箱可以仿真得到结果。Matlab/Simulink若在电路分析教学中合适运用,有利于提高电路分析的教学质量。 相似文献
8.
海带生长素IAA分离纯化及高效液相色谱分析 总被引:2,自引:0,他引:2
对海带(Laminaria japonica Aresch.)中的生长素IAA的分离纯化条件进行优化,结果以超声法破碎细胞、采用体积分数95%乙醇浸提,乙醚萃取,硅胶脱色,然后通过Sephadex LH20柱层析为最佳条件,利用反向高效液相色谱(RP-HPLC)方法对IAA进行了定性和定量分析.实验表明:该方法操作简便、准确,重现性好,毒性较低,通过RP-HPLC结果可初步确定纯化产物中含有IAA,产量可达65~95μg/kg(鲜重).研究结果为进一步生物活性的研究和海带生长素及其他植物生长促进剂的开发和利用奠定了基础. 相似文献
9.
针对图像训练对的去雾算法难以应对遥感图像中训练样本对不足,且模型泛化的问题,提出一种基于级联生成对抗网络(GAN)的遥感图像去雾方法。为解决成对遥感数据集的缺失,提出了学习雾生成的U-Net GAN(UGAN)和学习去雾的像素注意GAN(PAGAN)。所提方法通过UGAN学习如何使用未配对的清晰遥感图像和带雾遥感图像集在保留遥感图像细节的同时对无雾图像进行加雾处理,然后引导PAGAN学习如何正确地对此类图像进行去雾。为了减少生成的带雾遥感图像和去雾后遥感图像之间的差异,在PAGAN中加入自我注意机制,用生成器从低分辨率图像中所有位置的细节线索生成高分辨率细节特征,用判别器检查图像远端部分的细节特征是否彼此一致。与特征融合注意网络(FFANet)、门控上下文聚合网络(GCANet)和暗通道先验(DCP)等去雾方法相比,级联GAN方法无需大量成对数据来反复训练网络。实验结果表明该方法能够有效地去除雾和薄云,在目视效果和定量指标上均优于对比方法。 相似文献
10.
宋远明 《武汉理工大学学报(材料科学英文版)》2014,29(1):93-96
Circulating fluidized bed combustion (CFBC) ash can be used as supplementary cementitious material for concrete production for its high pozzolanic activity. We investigated the effect of curing conditions on the hydration and performance of CFBC ash-Portland cement system (30: 70, by mass) including hydration products, paste microstructure, linear expansion ratio, chemically combined water content and compressive strength. The results show that tobermorite rather than ettringite is generated under the condition of autoclaved curing. The expansion and mortar strength of the system cured in water is higher than those cured in air at a given age, and the strength and bulk volume may retract under the condition of air curing. In addition, autoclaved curing facilitates the increase of strength gain at early curing ages (the increase rate lowers down in the following ages) and the improvement of system volume stability. It is suggested that sufficient water is necessary for the curing of CFBC ash cementitious system, and autoclaved curing may be considered where volume stability is a primary concern. 相似文献