全文获取类型
收费全文 | 18675篇 |
免费 | 2296篇 |
国内免费 | 1263篇 |
专业分类
电工技术 | 1487篇 |
技术理论 | 1篇 |
综合类 | 1540篇 |
化学工业 | 2533篇 |
金属工艺 | 1304篇 |
机械仪表 | 1301篇 |
建筑科学 | 1435篇 |
矿业工程 | 662篇 |
能源动力 | 548篇 |
轻工业 | 1469篇 |
水利工程 | 472篇 |
石油天然气 | 807篇 |
武器工业 | 222篇 |
无线电 | 2463篇 |
一般工业技术 | 2061篇 |
冶金工业 | 721篇 |
原子能技术 | 273篇 |
自动化技术 | 2935篇 |
出版年
2024年 | 145篇 |
2023年 | 376篇 |
2022年 | 787篇 |
2021年 | 1190篇 |
2020年 | 833篇 |
2019年 | 607篇 |
2018年 | 714篇 |
2017年 | 773篇 |
2016年 | 674篇 |
2015年 | 964篇 |
2014年 | 1306篇 |
2013年 | 1357篇 |
2012年 | 1530篇 |
2011年 | 1573篇 |
2010年 | 1317篇 |
2009年 | 1203篇 |
2008年 | 1288篇 |
2007年 | 1146篇 |
2006年 | 997篇 |
2005年 | 808篇 |
2004年 | 538篇 |
2003年 | 374篇 |
2002年 | 347篇 |
2001年 | 297篇 |
2000年 | 225篇 |
1999年 | 172篇 |
1998年 | 125篇 |
1997年 | 93篇 |
1996年 | 75篇 |
1995年 | 88篇 |
1994年 | 88篇 |
1993年 | 63篇 |
1992年 | 34篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 19篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 10篇 |
1979年 | 3篇 |
1974年 | 3篇 |
1970年 | 2篇 |
1959年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Ren X Xue Y Liu J Zhang K Zheng J Luo G Guo C Mu Y Shen J 《Chembiochem : a European journal of chemical biology》2002,3(4):356-363
A novel dicyclodextrinyl ditelluride (2-TeCD) compound was devised as a functional mimic of the glutathione peroxidase (GPX) enzymes that normally remove hydroperoxides from the cell. The GPX activity of the mimic was found to be 46.7 U microM(-1), which is 46 times as active as Ebselen, a well-known GPX mimic. A detailed steady-state kinetic study was undertaken to probe the reason for the high catalytic efficiency of 2-TeCD. This high efficiency can be explained based on both the binding of the substrate to the cyclodextrin and the catalytic mechanism of 2-TeCD, which is different from that of diselenide compounds. 2-TeCD exhibits good water solubility and is chemically and biologically stable. The biological effect of 2-TeCD was evaluated by its ability to protect mitochondria from oxidative damage. 2-TeCD exhibited excellent antioxidant capacity in comparison with Ebselen. 相似文献
102.
103.
In this work, magnesia from natural brucite mineral has been used firstly for catalytic degradation of nitrobenzene and aniline
in presence of ozone. Compared with single ozonation, the catalytic ozonation accelerated markedly the degradation of nitrobenzene
and aniline. The influences of hydroxyl radical scavengers, pH values, and reaction temperatures on degradation were investigated.
It was found that the essential of catalysis was the homogeneous catalysis of hydroxyl ions in water, which accelerated the
generation of hydroxyl radicals. As a catalyst, magnesia from natural brucite has supplied an economical and feasible choice
for catalytic ozonation of nitrobenzene and aniline in industrial wastewater. 相似文献
104.
Zhenbao Liu Sicong Tang Weiwei Xu Shuhui Bu Junwei Han Kun Zhou 《Computer Graphics Forum》2014,33(7):269-278
Since indoor scenes are frequently changed in daily life, such as re‐layout of furniture, the 3D reconstructions for them should be flexible and easy to update. We present an automatic 3D scene update algorithm to indoor scenes by capturing scene variation with RGBD cameras. We assume an initial scene has been reconstructed in advance in manual or other semi‐automatic way before the change, and automatically update the reconstruction according to the newly captured RGBD images of the real scene update. It starts with an automatic segmentation process without manual interaction, which benefits from accurate labeling training from the initial 3D scene. After the segmentation, objects captured by RGBD camera are extracted to form a local updated scene. We formulate an optimization problem to compare to the initial scene to locate moved objects. The moved objects are then integrated with static objects in the initial scene to generate a new 3D scene. We demonstrate the efficiency and robustness of our approach by updating the 3D scene of several real‐world scenes. 相似文献
105.
A general method of chromatogram correction for skewed instrument spreading in gel permeation chromatography is presented. The correction method is so general that there is no restriction on the shape of the spreading function. It admits nonsymmetric, non-Gaussian as well as nonconvolution type. Aspects of solution techniques are discussed and an illustrative example is given to elucidate the method. 相似文献
106.
Absorption coefficients of phytoplankton, colored detrital matter (CDM), non-algal particles (NAP), colored dissolved organic matter (CDOM), and their relative contributions to total non-water absorption (at ? w) are essential variables for bio-optical and radiative transfer models. Light absorption properties showed large range and variability sampled at 194 stations throughout Lake Chaohu between May 2013 and April 2015. The at ? w was dominated by phytoplankton absorption (aph) and NAP absorption (ad). The contribution of CDOM absorption to at ? w was lower than 30%. Phytoplankton and NAP were the primary sources of spatial and vertical variability in absorption properties. Light absorption by CDOM, though significant in magnitude, was relatively constant. CDM absorption (adg) was dominated by NAP. The spatial variation of the absorption coefficients from each of the optically active constituents were driven by several main inflow rivers in the western and middle part of Lake Chaohu. Algal blooms and bottom resuspension contributed to vertical variability as observed by phytoplankton and NAP profiles. Specific absorption of phytoplankton had significant spatial and seasonal variations without vertical variation. The spectral slope of absorption showed no significant spatial variability (p > 0.05). Variations of absorption affected different ranges of remote sensing reflectance (Rrs) spectrum, thereby increasing the difficulty of applying the remote sensing algorithm in optically complex waters. Parameters and relationships presented in this study provide useful information for bio-optical models and remote sensing of lakes similar to Lake Chaohu in terms of optical properties. 相似文献
107.
108.
该文基于三维自由水面垂向分层动网格的Euler-Lagrangian模式,采用VC方式(Vertex-Centered)的非结构化有限体积方法离散三维浅水方程,模拟渤海的潮汐水流运动过程。以此为水动力背景场,采用油、水分离的Lagrangian粒子追踪模型,对渤海海域发生的溢油漂移扩散问题进行模拟。其油品的蒸发、乳化和溶解等风化作用以引入综合衰减系数的方式考虑。模型对油膜的漂移路径、厚度和面积进行了实时模拟和预测,用多个测站的同步连续实测值对水动力模式进行了参数率定与模型验证,油膜输运扩散的计算结果也与相关报告数据进行了对比,均吻合良好,说明模型具有较高的可靠性与重现性。 相似文献
109.
针对复杂工业系统动态非线性故障检测过程精度低和计算量大的问题,提出了一种改进的动态核主元分析故障检测方法,该方法首先利用不可区分度剔除相关程度较小或者不相关变量,减少数据量,然后通过观测值扩展对筛选后的新数据构建增广矩阵,并对矩阵使用核主元分析提取变量数据的非线性空间相关特征,最后通过监测T 2和SPE 两种统计量诊断出系统发生故障及识别故障变量。仿真实验证明,该方法能对风力发电机故障进行有效监测和诊断,与KPCA方法相比,改进的动态核主元分析方法对微小故障更为敏感。 相似文献
110.
Jianjun Lei Kun Feng Meimin Wu Shuai Li Chunping Hou 《Multimedia Tools and Applications》2014,72(1):825-842
Rate control plays an important role in regulating bit streams in video coding. In order to obtain good coding performance, the hierarchical B prediction structure has been adopted in Multi-view Video Coding (MVC). However, the conventional rate control scheme is not efficient in the hierarchical B prediction structure. In this paper, we propose a rate control algorithm to address this problem. First, the accurate estimation of Mean Absolute Distortion (MAD) of the current frame is desired for both quantization parameter (QP) selection and Rate Distortion Optimization (RDO). Considering the hierarchical B structure, a bi-directional MAD prediction model is proposed to predict the MAD of the current frame by using the actual MADs of the encoded frames in the lower Temporal Layers (TLs). Second, the number of header bits has a close relationship with the TLs in the hierarchical B prediction structure. Therefore, we propose an enhanced prediction method in which a proportional relationship of the header bits is introduced if the frames are located in different TLs. Experimental results show that our proposed algorithm can achieve both accurate target bit rate and good coding performance. 相似文献