全文获取类型
收费全文 | 5783篇 |
免费 | 823篇 |
国内免费 | 377篇 |
专业分类
电工技术 | 1512篇 |
综合类 | 586篇 |
化学工业 | 489篇 |
金属工艺 | 261篇 |
机械仪表 | 238篇 |
建筑科学 | 519篇 |
矿业工程 | 206篇 |
能源动力 | 147篇 |
轻工业 | 359篇 |
水利工程 | 128篇 |
石油天然气 | 93篇 |
武器工业 | 43篇 |
无线电 | 799篇 |
一般工业技术 | 481篇 |
冶金工业 | 311篇 |
原子能技术 | 27篇 |
自动化技术 | 784篇 |
出版年
2024年 | 35篇 |
2023年 | 103篇 |
2022年 | 195篇 |
2021年 | 225篇 |
2020年 | 230篇 |
2019年 | 179篇 |
2018年 | 171篇 |
2017年 | 188篇 |
2016年 | 195篇 |
2015年 | 212篇 |
2014年 | 345篇 |
2013年 | 324篇 |
2012年 | 370篇 |
2011年 | 417篇 |
2010年 | 314篇 |
2009年 | 346篇 |
2008年 | 362篇 |
2007年 | 417篇 |
2006年 | 352篇 |
2005年 | 329篇 |
2004年 | 255篇 |
2003年 | 236篇 |
2002年 | 236篇 |
2001年 | 189篇 |
2000年 | 166篇 |
1999年 | 127篇 |
1998年 | 82篇 |
1997年 | 83篇 |
1996年 | 57篇 |
1995年 | 56篇 |
1994年 | 40篇 |
1993年 | 20篇 |
1992年 | 32篇 |
1991年 | 17篇 |
1990年 | 20篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1982年 | 2篇 |
1977年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1959年 | 2篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有6983条查询结果,搜索用时 0 毫秒
1.
2.
The influence of an aggressive environment (0.6 M, aerated NaCl solution) on short fatigue crack initiation and growth behaviour has been studied. The study involved three major test series, namely: air fatigue, corrosion fatigue, and intermittent air fatigue/corrosion fatigue. The above tests carried out under fully reversed torsional loading conditions at a frequency of 5 Hz, showed that it was the non-metallic inclusions which took part in crack initiation resulting from debonding at metal matrix/inclusion interface and pitting of inclusions in both air and corrosove environments, respectively. Short fatigue crack growth results in these two environments obtained by using plastic replication technique, indicated a large effect of microstructure i.e. prior austenite grain boundaries. The stage/stages at which the environmental contribution was dominant has been discussed by considering the results achieved from intermittent tests. However, the mechanisms involved in corrosion fatigue short crack growth have also been described in the light of results obtained from futher investigations carried out by conducting corrosion fatigue tests under applied cathodic potential conditions and tests on hydrogen pre-charged specimens under air fatigue and uniaxial tension conditions. 相似文献
3.
Ackerman Steven J.; Hilsenroth Mark J.; Knowles Eric S. 《Canadian Metallurgical Quarterly》2005,42(2):225
The present study examines the concurrent and predictive relationships between therapist psychodynamic-interpersonal activity and therapist-rated alliance. Ratings from 45 patient and therapist dyads engaged in short term psychodynamic psychotherapy from a point early (3rd or 4th session) and late (the session at which 90% of the treatment was completed) in treatment were used. The results suggest that therapists who have positive views of the alliance early in treatment also have positive views of the alliance later in treatment. Therapists who used psychodynamic-interpersonal activities early in treatment also made use of psychodynamic-interpersonal activities later in treatment. Moreover, the use of psychodynamic-interpersonal activities early in treatment was positively related to both global and specific aspects of therapist-rated alliance late in treatment. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
4.
袁永强 《有色冶金设计与研究》2003,24(3):39-42
结合工程实例,对采用传统的短木桩加新兴的土工合成材料——土工网及碎石垫层构成复合基础,处理河岸挡墙软基进行探讨,该方法在软土层厚度不超过4.0m的条件下,技术可靠,施工简单,工期短,造价低。 相似文献
5.
Myers Mark G.; MacPherson Laura; McCarthy Denis M.; Brown Sandra A. 《Canadian Metallurgical Quarterly》2003,15(2):163
The goal of the present studies was to construct and validate a short form of the 50-item Smoking Consequences Questionnaire (SCQ; T. H. Brandon & T. B. Baker, 1991), a measure of smoking outcome expectancies. In Study 1, a 21-item short form (S-SCQ) was derived from a sample of 107 young adults previously treated for substance abuse. In Study 2, the measure was cross-validated on 125 adolescents in treatment for substance abuse. Confirmatory factor analyses revealed good model fit and factorial invariance for the 4 S-SCQ subscales across both samples. Validation analyses on each sample found that subscale scores generally correlated significantly with smoking-related variables. The present studies provide initial evidence for the utility of the S-SCQ when used with young adults and adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
This paper presents a partial scan algorithm, calledPARES (PartialscanAlgorithm based onREduced Scan shift), for designing partial scan circuits. PARES is based on the reduced scan shift that has been previously proposed for generating short test sequences for full scan circuits. In the reduced scan shift method, one determines proch FFs must be controlled and observed for each test vector. According to the results of similar analysis, PARES selects these FFs that must be controlled or observed for a large number of test vectors, as scanned FFs. Short test sequences are generated by reducing scan shift operations using a static test compaction method. To minimize the loss of fault coverage, the order of test vectors is so determined that the unscanned FFs are in the state required by the next test vector. If there are any faults undetected yet by a test sequence derived from the test vectors, then PARES uses a sequential circuit test generator to detect the faults. Experimental results for ISCAS'89 benchmark circuits are given to demonstrate the effectiveness of PARES. 相似文献
7.
利用短周期地脉动推断深层地基S波速度 总被引:3,自引:0,他引:3
从二维随机波场的相关理论出发,提出了如何从短周期地脉动(频率>0.5Hz)时域信号中计算Rayleigh波弥散曲线,进而反演深层地基剪切波(S波)速度的理论方法和分析技术,并结合实测信号的分析结果,探讨了该方法的可行性和实用性。 相似文献
8.
短毫米波和亚毫米波接收机的发展现状 总被引:1,自引:0,他引:1
本文概述了短毫米和亚毫米波接收机的发展现状,介绍了接收机的重要组成部件:混频器、振荡器和放大器的发展水平以及毫米波单片集成电路的现状,给出了接收机的最新性能指标。 相似文献
9.
Ken Kato Yasuhiro Kasuga Masanori Fujiwara Kazuo Onda 《Electrical Engineering in Japan》1996,116(4):94-108
Laboratory-scale and parametric experiments of SO2 and NOx removal from the simulated combustion gas by pulsed corona discharge have been performed by changing the combustion gas composition and temperature, the electrode configuration of plasma reactor, and the polarity of high-voltage electrode. The following results are obtained: 1) the higher the concentration of H2O and O2, the higher the efficiency of desulfurization and denitrification at the same specific input; 2) the pulsed corona discharge with a voltage pulsewidth as short as 200 ns of negative polarity shows the possibility to attain almost 90 percent deSOx and deNOx efficiency at the specific discharge input of 20 J/g, which is almost the same as the specific input in the electron-beam process; 3) the deNOx characteristics show a little temperature dependence in the range of 70 to 130°C, but the deSOx efficiency increases rapidly in the temperature region below 100°C suggesting the thermochemical dependence of deSOx reaction; 4) when desulfurization and denitrification proceed, the white dendritic powder deposits on the plasma reactor whose composition is identified to be 49 mol% (NH4)2SO4 and 47 mol% of 2NH4NO3 · (NH4)2SO4, and the ratio of SO2, NO and NH3 of the deposit is almost equal to that of supplied gas. 相似文献
10.