全文获取类型
收费全文 | 3058篇 |
免费 | 14篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 83篇 |
金属工艺 | 4篇 |
机械仪表 | 2篇 |
建筑科学 | 5篇 |
轻工业 | 45篇 |
石油天然气 | 1篇 |
无线电 | 35篇 |
一般工业技术 | 49篇 |
冶金工业 | 2779篇 |
自动化技术 | 66篇 |
出版年
2021年 | 4篇 |
2018年 | 4篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 17篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 11篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 13篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 91篇 |
1998年 | 892篇 |
1997年 | 446篇 |
1996年 | 318篇 |
1995年 | 186篇 |
1994年 | 129篇 |
1993年 | 190篇 |
1992年 | 45篇 |
1991年 | 27篇 |
1990年 | 36篇 |
1989年 | 28篇 |
1988年 | 36篇 |
1987年 | 33篇 |
1986年 | 31篇 |
1985年 | 38篇 |
1984年 | 11篇 |
1983年 | 14篇 |
1982年 | 25篇 |
1981年 | 17篇 |
1980年 | 37篇 |
1979年 | 5篇 |
1978年 | 12篇 |
1977年 | 61篇 |
1976年 | 123篇 |
1975年 | 6篇 |
1974年 | 8篇 |
1972年 | 4篇 |
1969年 | 6篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有3072条查询结果,搜索用时 15 毫秒
31.
32.
Y Munakata JL McClelland MH Johnson RS Siegler 《Canadian Metallurgical Quarterly》1997,104(4):686-713
Infants seem sensitive to hidden objects in habituation tasks at 3.5 months but fail to retrieve hidden objects until 8 months. The authors first consider principle-based accounts of these successes and failures, in which early successes imply knowledge of principles and failures are attributed to ancillary deficits. One account is that infants younger than 8 months have the object permanence principle but lack means-ends abilities. To test this, 7-month-olds were trained on means-ends behaviors and were tested on retrieval of visible and occluded toys. Means-ends demands were the same, yet infants made more toy-guided retrievals in the visible case. The authors offer an adaptive process account in which knowledge is graded and embedded in specific behavioral processes. Simulation models that learn gradually to represent occluded objects show how this approach can account for success and failure in object permanence tasks without assuming principles and ancillary deficits. 相似文献
33.
34.
35.
MH West RE Barsley JE Hall S Hayne M Cimrmancic 《Canadian Metallurgical Quarterly》1992,37(6):1480-1488
This article is a discussion of the use of narrow-band light sources coupled with cameras equipped with band-pass filters to document patterned injuries on human skin. Several case reports are included. 相似文献
36.
Can a few seconds of high school teachers' nonverbal (NV) behavior predict students' ratings of these teachers (SRT)? Yes, but NV-SRT relations varied among various instructional situations. NV behaviors while administering the class and using the board were unrelated to SRT. Positive judgments of NV behavior while disciplining the class and interacting with students were positively related to SRT. NV behaviors in frontal teaching were negatively related to SRT. The most negative NV-SRT relations were found for teachers' differential NV behavior toward high- versus low-achieving students. Teacher differentiality and SRT have rarely been investigated in high school. The structure of SRT seems to differ between high school and college, and students' anger about teachers' differentiality strongly predicted their evaluations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
The viability of developing an SiC fibre-reinforced titanium/titanium aluminide hybrid matrix composite was explored. The
hybrid composites are expected to be used at temperatures beyond those attainable in conventional titanium matrix composites
while improving the damage tolerance of the titanium aluminide matrix composites. The room-temperature mechanical characteristics
studied were tensile strength, fracture toughness, low-cycle fatigue life and fatigue crack growth rate. The mechanisms of
damage initiation and propagation under various loading conditions were also characterized. The directions for developing
a satisfactory composite with hybrid titanium/titanium aluminide matrix are also addressed. 相似文献
38.
Methotrexate therapy in rheumatoid arthritis: a life table review of 587 patients treated in community practice 总被引:2,自引:0,他引:2
R Buchbinder S Hall PN Sambrook GD Champion A Harkness D Lewis GO Littlejohn MH Miller PF Ryan 《Canadian Metallurgical Quarterly》1993,20(4):639-644
To determine whether methotrexate (MTX) maintains its effectiveness in rheumatoid arthritis (RA) in the setting of community based private rheumatology practice we used life table analysis to review the combined experience of a group of these practices. Of 587 patients with RA who started to take MTX, total termination rate at 70 months was 24.4% with most terminations prompted by drug toxicity. Older age (greater than 65 years) was associated with higher rates of toxicity. Treatment termination rates varied substantially between rheumatologists. We conclude that MTX therapy for RA is well tolerated and maintains effectiveness for at least 70 months. 相似文献
39.
Intramuscular phenol neurolysis is a well-known procedure used to decrease spasticity and improve function in patients who have failed to respond to more conservative forms of intervention. Traditionally, this approach has been limited to spasticity reduction in limb muscles, and its use in managing spasticity of the facial muscles has not been described in the literature. This case report describes a new and previously unreported application of intramuscular neurolysis for managing severe unrelenting facial muscle spasticity in a postanoxic encephalopathic patient. Prior to the procedure, hypertonicity in the orbicularis oris muscle was so profound that it limited speech and affected cosmetic, hygienic, and nutritional status. After intramuscular phenol neurolysis of the orbicularis oris muscle, the patient's level of functioning improved. 相似文献
40.
In enteric bacteria, chromosomally encoded permeases specific for lactose, maltose, and melibiose are allosterically regulated by the glucose-specific enzyme IIA of the phosphotransferase system. We here demonstrate that the plasmid-encoded raffinose permease of enteric bacteria is similarly subject to this type of inhibition. 相似文献