全文获取类型
收费全文 | 7818篇 |
免费 | 647篇 |
国内免费 | 397篇 |
专业分类
电工技术 | 398篇 |
综合类 | 479篇 |
化学工业 | 1232篇 |
金属工艺 | 509篇 |
机械仪表 | 399篇 |
建筑科学 | 605篇 |
矿业工程 | 362篇 |
能源动力 | 176篇 |
轻工业 | 454篇 |
水利工程 | 147篇 |
石油天然气 | 661篇 |
武器工业 | 56篇 |
无线电 | 962篇 |
一般工业技术 | 952篇 |
冶金工业 | 382篇 |
原子能技术 | 54篇 |
自动化技术 | 1034篇 |
出版年
2024年 | 50篇 |
2023年 | 148篇 |
2022年 | 285篇 |
2021年 | 358篇 |
2020年 | 303篇 |
2019年 | 268篇 |
2018年 | 261篇 |
2017年 | 290篇 |
2016年 | 252篇 |
2015年 | 352篇 |
2014年 | 397篇 |
2013年 | 516篇 |
2012年 | 499篇 |
2011年 | 537篇 |
2010年 | 461篇 |
2009年 | 445篇 |
2008年 | 383篇 |
2007年 | 423篇 |
2006年 | 410篇 |
2005年 | 353篇 |
2004年 | 218篇 |
2003年 | 187篇 |
2002年 | 152篇 |
2001年 | 142篇 |
2000年 | 155篇 |
1999年 | 199篇 |
1998年 | 161篇 |
1997年 | 118篇 |
1996年 | 114篇 |
1995年 | 105篇 |
1994年 | 92篇 |
1993年 | 54篇 |
1992年 | 47篇 |
1991年 | 36篇 |
1990年 | 22篇 |
1989年 | 21篇 |
1988年 | 15篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有8862条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Marijan Dravinski Yuqing Niu 《International journal for numerical methods in engineering》2002,53(2):445-472
Time‐harmonic Green's functions for a triclinic anisotropic full‐space are evaluated through the use of a symbolic computation system.This procedure allows evaluation of the Green's functions for the most general anisotropic materials. The proposed computational algorithms are programmed in a MATLAB environment by incorporating symbolic calculations performed using Maple Computer Algebra System. Extensive testing of the numerical results has been performed for both displacement and stress fields. The tests demonstrate the accuracy of the proposed algorithm in evaluating the Green's functions. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
995.
通过屯兰矿无纸化办公OA系统的开发和应用,创造一个集成的办公环境,提高工作效率,使所有的办公人员都在同一个桌面环境下一起工作,摆脱时间和地域的限制,实现协同工作与知识管理。使其有效地为领导决策提供支持、达到信息充分共享、无纸化办公、文档一体化管理、提高工作效率、规范企业管理、降低办公费用等目标。 相似文献
996.
地下工程中逆作法的现状及发展趋势 总被引:2,自引:0,他引:2
本文根据国内外地下工程中逆作法施工的现状,分析研究了逆作法施工的优缺点,推荐并介绍了几种提高过作法施工质量的关键技术,总结并提出了逆作法发展的趋势。 相似文献
997.
Jia Dongyong Zhang Jianmin Niu Zhigang Sun Hongchang 《Frontiers of Mechanical Engineering in China》2007,2(2):235-238
This paper analyzed the inverse kinematics for the new Parallel rotate slider-XY axes (PRS-XY) style hybrid machining tool and educed the five axes linkage inverse kinematics transform formula on the basis of the coordinates
of the X, Y, Z, A and B virtual axes. The program for the PRS-XY style hybrid machining tool in accordance with the program manner for the common
numerical control (NC) machine tool was made. The results of the experiments prove that the inverse kinematics transform formula
is correct.
Translated from Journal of Modern Manufacturing Engineering, 2006, (4): 33–35, 49 [译自: 现代制造工程] 相似文献
998.
光纤式表面粗糙度测量仪的研制 总被引:1,自引:0,他引:1
本文论述了光纤表面粗糙度测量仪研制过程中关键问题的解决方法,对非线性特性的参数计算,零点漂移,信号噪声,不同加工表面特性差异的处理都给出了完美的解决方法。该仪器以光散射理论为测量原理,用光纤为传输媒介,并用单片机8098进行计算,数据处理和测量智能控制。 相似文献
999.
In a companion paper (see ibid., p.747-54, June 1993) studying short-pulse radiation from current elements in the presence of plane layered dielectric media, various alternatives for constructing the transient field in terms of spectral-domain wave functions are explored. Two distinctive synthesis options are structured around conventional time-harmonic and nonconventional time-dependent basis wave functions, respectively. To understand the characteristic properties of each, the frequency-wavenumber dispersion relation for the layered environment is explored here in detail. Especially interesting is the behavior of the nonconventional time-domain leaky modes, which exhibit anomalies not encountered in their conventional time-harmonic counterparts. An example is given of how these time-domain modal basis fields synthesize highly resolved short-pulse radiation from a source in a dielectric layer 相似文献
1000.
Fibrinopeptide B (M(r) 1552.58) was employed as a calibration compound for matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) post-source decay (PSD) fragment ion analysis in the negative mode. Experiments were performed by using both continuous and delayed extraction, with the maximum reflectron voltages being 30 and 21 kV, respectively. For comparison, a common positive ion PSD calibrant, ACTH(18-39) (M(r) 2466.7), was also employed with positive ion calibration constants being applied to negative ion spectra. Using fibrinopeptide B as the calibrant, the negative ion PSD results for angiotensin II (M(r) 1046.2), renin substrate tetradecapeptide (horse) (M(r) 1759.0), and the custom-synthesized peptide (K2G4)2 (M(r) 987.1) showed a factor of 1.5-2 improvement in absolute mass accuracy. Typical absolute mass-to-charge ratio accuracies were within +/- 1 Thompson and were achieved even when the peptide being analyzed was more massive than fibrinopeptide B. In addition, both calibrants showed increased accuracy when experiments were conducted in the delayed extraction mode. Other advantages of using fibrinopeptide B are its moderate cost and the ability to perform calibration and sample analysis for negative ion PSD under the same instrumental conditions. 相似文献