全文获取类型
收费全文 | 7463篇 |
免费 | 636篇 |
国内免费 | 435篇 |
学科分类
工业技术 | 8534篇 |
出版年
2024年 | 15篇 |
2023年 | 69篇 |
2022年 | 135篇 |
2021年 | 166篇 |
2020年 | 178篇 |
2019年 | 157篇 |
2018年 | 148篇 |
2017年 | 207篇 |
2016年 | 226篇 |
2015年 | 258篇 |
2014年 | 515篇 |
2013年 | 476篇 |
2012年 | 631篇 |
2011年 | 631篇 |
2010年 | 499篇 |
2009年 | 507篇 |
2008年 | 459篇 |
2007年 | 613篇 |
2006年 | 488篇 |
2005年 | 413篇 |
2004年 | 344篇 |
2003年 | 255篇 |
2002年 | 237篇 |
2001年 | 178篇 |
2000年 | 145篇 |
1999年 | 114篇 |
1998年 | 96篇 |
1997年 | 81篇 |
1996年 | 47篇 |
1995年 | 46篇 |
1994年 | 36篇 |
1993年 | 31篇 |
1992年 | 29篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1980年 | 4篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有8534条查询结果,搜索用时 265 毫秒
81.
文章根据时代变迁、社会发展和市场需求,以独立院校建筑学专业及一年级设计课教学定位为背景,结合天津地区两所高校在一年级设计课教学等多方面差异化比较分析,辩证分析独立院校建筑学一年级设计基础课程关于教学内容、培养模式、实践教学、考核方式等方面的教学特色,意在为培养“执行建筑师”建造牢固基础。 相似文献
82.
论文提出了一种基于快速独立分量分析的高光谱图像降维算法.利用虚拟维数算法估计需要保留的独立分量数目,采用非监督端元提取算法自动获取端元矢量,并对快速独立分量分析的混合矩阵进行有效初始化.采用最大噪声分离变换对原始数据进行预处理,利用快速独立分量分析从变换后的主分量中依次提取出各端元对应的独立分量,最后对各个独立分量分别实施无损压缩.实验结果表明,该算法降维后的独立分量具有较好的地物分类性能,并且可以获得较好的压缩性能. 相似文献
83.
84.
Poly(glycidyl methacrylate) (PGMA) beads with an average size of 350 μm were synthesized by suspension polymerization technique. The PGMA beads were first modified with iminodiacetonitrile (IDAN). Then, the IDAN‐modified beads were subsequently modified by hydroxylamine. The IDAN modification and the conversion of the nitrile groups to amidoxime were followed by FT‐IR spectroscopy. The surface morphology and thermal behavior of the PGMA and its modified forms were also characterized by scanning electron microscopy and thermogravimetric analysis techniques, further confirming modification and amidoximation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
85.
The synthesis and application of polybenzoxazine adsorption resin was studied. First, the precursor was synthesized by the solventless method. And then a kind of spherical and granular polybenzoxazine resin was obtained using reverse‐phase suspension polymerization technique in the process of solidification. Besides, the influence of dispersion medium, the volume ratio of precursor to medium, the solidification temperature, and the agitation speed were studied in detail in the process of polymerization. Second, the spherical shape of the polybenzoxazine resin was identified by scanning electronic microscope and the thermal stability of resin was measured by thermogravimetric analysis. Finally, the adsorption capacity of the spherical resin on pyridine was studied in cyclohexane systems. The correlation coefficient of Langmuir adsorption constant temperature line was bigger than 0.99, which indicated that the equilibrium sorption date was coincident with the Langmuir isotherm equation. And the saturated adsorptive capacity of dried resin achieved 222.2 mg g?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
86.
In this paper, a generalized robust H ∞ filtering method is proposed for a class of singular Markovian jump systems, whose generality is mainly embodied that the desired filter could bear perturbances in terms of uncertainties on its parameter matrices. Firstly, an LMI condition of robust mode‐dependent filter is developed. Based on the given result, a new approach to mode‐independent H ∞ filter is presented, which establishes a direct connection between mode‐dependent and mode‐independent filters. Secondly, when the transition rate matrix is with elementwise bounded uncertainties or partially unknown, sufficient conditions of such robust mode‐dependent and mode‐independent filters are all developed within LMI frameworks. Finally, a numerical example is used to demonstrate the effectiveness of the proposed methods. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
87.
Won Seok Lyoo Chan Sik Park Joon Ho Kim Han Do Ghim Ji Youl Lee Jinwon Lee Chul Joo Lee 《应用聚合物科学杂志》2003,88(3):832-839
Vinyl pivalate (VPi) was suspension‐polymerized to synthesize high molecular weight (HMW) poly(vinyl pivalate) (PVPi) with a high conversion above 95% for a precursor of syndiotacticity‐rich HMW poly(vinyl alcohol) (PVA). Also, the effects of the polymerization conditions on the conversion, molecular weight, and degree of branching (DB) of PVPi and PVA prepared by the saponification of PVPi were investigated. Bulk polymerization was slightly superior to suspension polymerization in increasing the molecular weight of PVA. On the other hand, the latter was absolutely superior to the former in increasing the conversion of the polymer, indicating that the suspension polymerization rate of VPi was faster than that of the bulk one. These effects could be explained by a kinetic order of a 2,2′‐azobis(2,4‐dimethylvaleronitrile) concentration calculated by the initial rate method. Suspension polymerization of VPi at 55°C by controlling various polymerization factors proved to be successful in preparing PVA of HMW [number‐average degree of polymerization (Pn): 8200–10,500], high syndiotactic diad content (58%), and very high yield (ultimate conversion of VPi into PVPi: 94–98%). In the case of the bulk polymerization of VPi at the same conditions, the maximum Pn and conversion of 10,700–11,800 and 32–43% were obtained, respectively. The DB was lower and the Pn was higher with PVA prepared from PVPi polymerized at lower initiator concentrations. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 832–839, 2003 相似文献
88.
介绍了室式分离机的转鼓结构及工作过程.为提高这种机器的分离效率,重点对室式分离机的转鼓结构做了改进.通过对室式分离机改进型转鼓中悬浮液的流动速度进行分析,为实现不停机自动排渣提供理论基础. 相似文献
89.
GPS定位速度快、精度高,在土建等工程中得到普及应用,针对GPS定位中的精度保证问题提出了一些措施和建议,可供实际应用参考. 相似文献
90.
基于1/4汽车悬架为控制对象,建立了汽车悬架动力学模型.以线性二次型最优(LQG)控制和改进后的半主动开关(on-off)控制为控制策略,在MATLAB/Simulink软件平台上进行仿真.与被动悬架比较,采用正弦激励下的频域分析和随机路面激励下的时域分析,证明了LQG控制和半主动开关控制在汽车控制工程中的可行性. 相似文献