全文获取类型
收费全文 | 48863篇 |
免费 | 5128篇 |
国内免费 | 3635篇 |
专业分类
电工技术 | 4478篇 |
综合类 | 4320篇 |
化学工业 | 6769篇 |
金属工艺 | 2798篇 |
机械仪表 | 3505篇 |
建筑科学 | 3932篇 |
矿业工程 | 1416篇 |
能源动力 | 1548篇 |
轻工业 | 3291篇 |
水利工程 | 1114篇 |
石油天然气 | 2122篇 |
武器工业 | 781篇 |
无线电 | 6146篇 |
一般工业技术 | 5051篇 |
冶金工业 | 1721篇 |
原子能技术 | 735篇 |
自动化技术 | 7899篇 |
出版年
2024年 | 224篇 |
2023年 | 654篇 |
2022年 | 1294篇 |
2021年 | 1953篇 |
2020年 | 1490篇 |
2019年 | 1207篇 |
2018年 | 1339篇 |
2017年 | 1534篇 |
2016年 | 1399篇 |
2015年 | 2163篇 |
2014年 | 2614篇 |
2013年 | 3207篇 |
2012年 | 3547篇 |
2011年 | 3789篇 |
2010年 | 3679篇 |
2009年 | 3569篇 |
2008年 | 3456篇 |
2007年 | 3286篇 |
2006年 | 3083篇 |
2005年 | 2495篇 |
2004年 | 1944篇 |
2003年 | 1757篇 |
2002年 | 1814篇 |
2001年 | 1626篇 |
2000年 | 1169篇 |
1999年 | 805篇 |
1998年 | 490篇 |
1997年 | 389篇 |
1996年 | 358篇 |
1995年 | 284篇 |
1994年 | 207篇 |
1993年 | 194篇 |
1992年 | 160篇 |
1991年 | 92篇 |
1990年 | 93篇 |
1989年 | 63篇 |
1988年 | 50篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 21篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1976年 | 3篇 |
1973年 | 4篇 |
1959年 | 5篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Hao Liang Zhiqiang Zheng Zengchang Li Jie Xu Biao Chen Hui Zhao Qijin Zhang Hai Ming 《应用聚合物科学杂志》2004,93(2):681-685
A step‐index polymer optical fiber (SI POF) containing Rhodamine B in poly(methyl methacrylate) (PMMA) has been fabricated by a preform technique. Fluorescence of different fiber lengths were observed and discussed. A high gain (23 dB) for a SI POF with 60‐cm length, 400‐μm diameter was obtained. The Rhodamine B content of the doped SI POF is 5 ppm‐wt. The signal wavelength providing the highest gain for a 60 cm SI POF is around 630 nm, and the optimum fiber length is about 60 cm at 10 kW launched pump power. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 681–685, 2004 相似文献
62.
63.
64.
Yulian Jiang Jianchang Liu Shubin Tan Pingsong Ming 《International journal of systems science》2014,45(9):1869-1879
In this paper, a robust consensus algorithm is developed and sufficient conditions for convergence to consensus are proposed for a multi-agent system (MAS) with exogenous disturbances subject to partial information. By utilizing H∞ robust control, differential game theory and a design-based approach, the consensus problem of the MAS with exogenous bounded interference is resolved and the disturbances are restrained, simultaneously. Attention is focused on designing an H∞ robust controller (the robust consensus algorithm) based on minimisation of our proposed rational and individual cost functions according to goals of the MAS. Furthermore, sufficient conditions for convergence of the robust consensus algorithm are given. An example is employed to demonstrate that our results are effective and more capable to restrain exogenous disturbances than the existing literature. 相似文献
65.
We present an interactive method for mesh segmentation that is inspired by the classical live‐wire interaction for image segmentation. The core contribution of the work is the definition and computation of wires on surfaces that are likely to lie at segment boundaries. We define wires as geodesics in a new tensor‐based anisotropic metric, which improves upon previous metrics in stability and feature‐awareness. We further introduce a simple but effective mesh embedding approach that allows geodesic paths in an anisotropic path to be computed efficiently using existing algorithms designed for Euclidean geodesics. Our tool is particularly suited for delineating segmentation boundaries that are aligned with features or curvature directions, and we demonstrate its use in creating artist‐guided segmentations. 相似文献
66.
Yi Zhang Bin Li Pinggen Rao Ming Lü Jianqing Wu 《Journal of the American Ceramic Society》2007,90(5):1615-1618
The leucite crystallization kinetics from a hydrothermally derived precursor seeded with nano-crystalline leucite was investigated by X-ray diffraction and non-isothermal differential thermal analysis. The nano-crystalline leucite was prepared by high-energy milling of high-purity leucite powder and the leucite precursor was prepared by the hydrothermal method of silica sol, aluminum nitrate, and potassium nitrate. After the seeds were introduced, the crystallization temperature of the precursor was lowered by 100°C and the transition phase kalsilite did not appear during the crystallization process. When the seeded precursor was heat treated at 700°C, a small amount of cubic leucite was stabilized to room temperature. The seeded precursor showed an exothermic peak between 800° and 920°C under different heating rates. The activation energy for the growth of leucite from the seeded precursor was 256(SD9) kJ/mol. 相似文献
67.
Haixia Xiang Cuiping Yu Jinchun Gao Shulan Li Yongle Wu Ming Su Yuanan Liu 《国际射频与微波计算机辅助工程杂志》2014,24(3):401-411
This article introduces the concurrent dual‐band digital predistortion (DPD) architecture with only one upconvertion unit, which is suitable for the linearization of wideband power amplifiers (PAs) excited by concurrent dual‐band signals. By extending the conventional dynamic deviation reduction (DDR) model to the concurrent dual‐band mode, we propose two DDR‐based concurrent dual‐band models, the dual‐band DDR (DB‐DDR) model and the simplified dual‐band DDR (SDB‐DDR) model. The performance of these two models is experimentally assessed with two types of wideband PAs (a GaN Class F PA and a GaN Doherty PA) driven by the concurrent dual‐band signal, and compared with the prior two‐dimensional digital predistortion (2D‐DPD) model and the two‐dimensional modified memory polynomial (2D‐MMP) model. The results prove the good DPD performance and low computational complexity of the proposed models. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:401–411, 2014. 相似文献
68.
管材超声波分层检测作为控制产品质量的关键步骤,必须引起相关从业人员的重视,特别是要重点分析分层缺陷检测中盲区的构成原因和分布特征。只有这样,才能切实保证检测结果的准确性,更好地控制管材质量。通过对超声波分层缺陷检测的重要性进行阐释,分析了其中盲区的构成和分布等问题。 相似文献
69.
70.