全文获取类型
收费全文 | 6338篇 |
免费 | 51篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 22篇 |
综合类 | 3篇 |
化学工业 | 355篇 |
金属工艺 | 83篇 |
机械仪表 | 39篇 |
建筑科学 | 93篇 |
矿业工程 | 10篇 |
能源动力 | 31篇 |
轻工业 | 195篇 |
水利工程 | 9篇 |
石油天然气 | 26篇 |
无线电 | 244篇 |
一般工业技术 | 373篇 |
冶金工业 | 4627篇 |
原子能技术 | 17篇 |
自动化技术 | 271篇 |
出版年
2021年 | 24篇 |
2019年 | 20篇 |
2018年 | 21篇 |
2016年 | 30篇 |
2015年 | 26篇 |
2014年 | 36篇 |
2013年 | 104篇 |
2012年 | 55篇 |
2011年 | 67篇 |
2010年 | 73篇 |
2009年 | 72篇 |
2008年 | 81篇 |
2007年 | 75篇 |
2006年 | 76篇 |
2005年 | 59篇 |
2004年 | 59篇 |
2003年 | 66篇 |
2002年 | 67篇 |
2001年 | 43篇 |
2000年 | 60篇 |
1999年 | 172篇 |
1998年 | 1307篇 |
1997年 | 732篇 |
1996年 | 536篇 |
1995年 | 289篇 |
1994年 | 297篇 |
1993年 | 303篇 |
1992年 | 75篇 |
1991年 | 87篇 |
1990年 | 111篇 |
1989年 | 91篇 |
1988年 | 100篇 |
1987年 | 100篇 |
1986年 | 87篇 |
1985年 | 57篇 |
1984年 | 39篇 |
1983年 | 51篇 |
1982年 | 50篇 |
1981年 | 43篇 |
1980年 | 75篇 |
1979年 | 38篇 |
1978年 | 39篇 |
1977年 | 110篇 |
1976年 | 239篇 |
1975年 | 35篇 |
1974年 | 14篇 |
1972年 | 20篇 |
1971年 | 14篇 |
1970年 | 21篇 |
1969年 | 12篇 |
排序方式: 共有6398条查询结果,搜索用时 390 毫秒
51.
The kinematic error compensation of robot manipulators is at present being attempted by improving the precision of the nominal robot kinematic parameters. This paper addresses the problem of kinematic compensation using a new mathematical joint model proposed to account for shortcomings in existing methods. The corrected manipulator transformation is formulated in terms of “generalized Jacobians”: relating differential errors at the joints to the differential change in the manipulator transformation. The details of application are discussed for a particular industrial manipulator. 相似文献
52.
Dynamically-compacted Inconel 718 powder has been heat treated in order to examine the evolution of microstructural recovery and hardness, recrystallization and grain coarsening, and interparticle-adhesion and fracture response. Following dynamic compaction the compacted powders are imperfectly bonded and the material is fairly brittle; the shock wave has caused significant hardening; local microstructures and properties are variable from particle surface to interior. Following annealing at 900 to 1000° C, virtually complete recrystallization occurs giving rise to a material which is softened and has a fine-scale microstructure. Little improvement in fracture response occurs, however, because the oxidized prior-particle surfaces do not weld together. Shock-wave consolidation offers the possibility of producing monolithic, microstructurally-fine materials, providing suitable post-consolidation thermo-mechanical processes are developed to overcome the limited bonding problem. 相似文献
53.
54.
Zautra Alex J.; Okun Morris A.; Robinson Sharon E.; Lee Douglas; Roth Sanford H.; Emmanual Jansen 《Canadian Metallurgical Quarterly》1989,8(1):1
Studied the relation between life stress and immune parameters for 33 30–70 yr old female rheumatoid arthritis (RA) patients interviewed during 3 routine monthly clinic checkups. Life stress from major and minor events, coping efficacy, and self-reported psychological distress were assessed, and immunofluorescence of T-cells and B-cells was performed on the blood drawn during each visit. Small stressful events were positively related to the proportion of circulating B-cells, psychological distress was inversely related to proportion of circulating T-cells, and major life events were associated with lower T-helper/T-suppressor cell ratios. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
55.
56.
57.
PA Smanik KY Ryu KS Theil EL Mazzaferri SM Jhiang 《Canadian Metallurgical Quarterly》1997,138(8):3555-3558
The active iodide uptake of the thyroid gland in humans is mediated by the human sodium iodide symporter (hNIS). In this report, we show that hNIS expression was detected primarily in thyroid tissue, but also in breast, colon, and ovary tissues. Expression of hNIS is greatly reduced in thyroid tumors compared to normal thyroid tissue. Among tumor tissues, hNIS expression appears to be variable, consistent with the variable response to radioiodide treatment observed for thyroid carcinomas. The coding region of hNIS is interrupted by 14 introns, and the nucleotide sequence of each exon-intron junction is reported. Using this information, an alternatively spliced form of hNIS was identified. Finally, the chromosome location of the hNIS gene was mapped to chromosome 19p. 相似文献
58.
59.
T. M. Morris 《Journal of the Institute of Brewing》1987,93(1):13-17
Haze measurements have been obtained for suspensions of polystyrenelatex particles of known diameter using two light scattering instruments which measure at angles of 90° and 13° respectively. The results agree well with the theory of light scattering and demonstrate the significant effects of particle size and angle of detection upon the instrumental values for haze. This information has been used to correlate the particle size distributions of a number of beers, as measured by Coulter Counter, with the corresponding, measured haze values. 相似文献
60.
P Carder AH Wyllie CA Purdie RG Morris S White J Piris CC Bird 《Canadian Metallurgical Quarterly》1993,8(5):1397-1401
Mutations in the p53 tumour suppressor gene are amongst the most frequent genetic abnormalities acquired in tumours. Recent studies in vitro suggest that mutant p53 destabilises the genome and facilitates development of aneuploidy. Here, in a study of 83 colorectal carcinomas, we demonstrate that alterations in p53 (detected by immunocytochemical stabilisation) precede and apparently facilitate divergence of aneuploid sub-clones. Aneuploidy in these tumours (but not those with normal p53) is predominantly in the subtetraploid range, suggesting that endoreduplication is important in its origin. This association with a specific phase of carcinoma progression is not shared by other commonly acquired genetic abnormalities in these tumours. These observations highlight the critical role of p53 in the regulation of abnormal chromosome replication and afford an explanation for the association between p53 abnormalities, aneuploidy and biological aggression in cancer. 相似文献