全文获取类型
收费全文 | 2418篇 |
免费 | 96篇 |
国内免费 | 64篇 |
专业分类
电工技术 | 62篇 |
综合类 | 140篇 |
化学工业 | 124篇 |
金属工艺 | 59篇 |
机械仪表 | 52篇 |
建筑科学 | 58篇 |
矿业工程 | 18篇 |
能源动力 | 29篇 |
轻工业 | 114篇 |
水利工程 | 27篇 |
石油天然气 | 9篇 |
武器工业 | 5篇 |
无线电 | 78篇 |
一般工业技术 | 83篇 |
冶金工业 | 1592篇 |
原子能技术 | 8篇 |
自动化技术 | 120篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 36篇 |
2021年 | 40篇 |
2020年 | 38篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 22篇 |
2016年 | 25篇 |
2015年 | 27篇 |
2014年 | 39篇 |
2013年 | 45篇 |
2012年 | 70篇 |
2011年 | 73篇 |
2010年 | 73篇 |
2009年 | 77篇 |
2008年 | 73篇 |
2007年 | 82篇 |
2006年 | 78篇 |
2005年 | 52篇 |
2004年 | 37篇 |
2003年 | 30篇 |
2002年 | 24篇 |
2001年 | 31篇 |
2000年 | 16篇 |
1999年 | 50篇 |
1998年 | 464篇 |
1997年 | 294篇 |
1996年 | 169篇 |
1995年 | 97篇 |
1994年 | 71篇 |
1993年 | 91篇 |
1992年 | 16篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 7篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 12篇 |
1980年 | 16篇 |
1979年 | 1篇 |
1978年 | 9篇 |
1977年 | 48篇 |
1976年 | 131篇 |
1975年 | 6篇 |
1955年 | 2篇 |
排序方式: 共有2578条查询结果,搜索用时 0 毫秒
131.
132.
EM Yoshida LA Mandl SR Erb AB Buckley CH Scudamore NA Buskard 《Canadian Metallurgical Quarterly》1997,24(4):274-275
The loss of immunotolerance has been implicated in the pathogenesis of both primary biliary cirrhosis (PBC) and idiopathic, immune-mediated thrombocytopenic purpura (ITP). An association between these two autoimmune diseases has been well described. We describe a 41-year-old woman in whom ITP developed 457 days after liver transplantation for PBC while receiving immunosuppressive medications sufficient to maintain allograft function. Our case report, the first to describe post-transplant ITP in association with PBC, demonstrates the persistence of the underlying immune dysregulation of PBC after transplantation. The practice of decreasing the dosage of immunosuppressive medication to maintenance levels after transplantation may unmask the effects of this defect in immunotolerance. 相似文献
134.
Previous research has documented differences in the pattern of EEG activation between 3-month-old infants of depressed mothers and infants of nondepressed mothers. In the present study, EEG was recorded in even younger 1-month-old infants of depressed and nondepressed mothers. The infants of depressed mothers exhibited greater relative right frontal EEG asymmetry (due to reduced left frontal activation), and this pattern at 1 month was significantly related to 3-month EEG asymmetry. Right frontal EEG asymmetry was also related to more frequent negative facial expressions (sad and pre-cry faces) during the Brazelton exam. Finally, the infants of depressed mothers showed more indeterminate sleep, were less active, and cried less than infants of nondepressed mothers. 相似文献
135.
KB Avraham T Hasson T Sobe B Balsara JR Testa AB Skvorak CC Morton NG Copeland NA Jenkins 《Canadian Metallurgical Quarterly》1997,6(8):1225-1231
Deafness is the most common form of sensory impairment in humans. Mutations in unconventional myosins have been found to cause deafness in humans and mice. The mouse recessive deafness mutation, Snell's waltzer, contains an intragenic deletion in an unconventional myosin, myosin VI (locus designation, Myo6). The requirement for Myo6 for proper hearing in mice makes this gene an excellent candidate for a human deafness disorder. Here we report the cloning and characterization of the human unconventional myosin VI (locus designation, MYO6) cDNA. The MYO6 gene maps to human chromosome 6q13. The isolation of the human gene makes it now possible to determine if mutations in MYO6 contribute to the pathogenesis of deafness in the human population. 相似文献
136.
137.
NA Johnson 《Canadian Metallurgical Quarterly》1997,162(8):564-570
Medical officers in the U.S. Army are tasked with screening, evaluating, and processing soldiers in accordance with AR 600-9, the Army's height and weight standards regulation. This essay traces the origins of the Army's weight standards to the present day. The Army's height and weight standards have varied markedly, from the crude subjective assessment of selective service candidates at the local draft examination boards at the turn of the century to the modern, highly accurate methods currently used in anthropomorphic research. The strictness of military recruitment and retention standards closely paralleled changing military personnel requirements in any particular era. Racial integration and the influx of women into the ranks had noteworthy effects on this history. The evolution of the Army's weight-control program and screening standards reflects advancements in medical knowledge and technology, societal and political pressure, and the empirical tests of world wars. 相似文献
138.
Edible coatings with low potassium sorbate permeability could be used to increase the microbial stability of food surfaces. However, such coatings could induce anaerobic food conditions if their oxygen permeability were low. the oxygen permeability of an edible emulsion film (average thickness, 55 μm), composed of methylcellulose and palmitic acid (weight ratio of 3:1), was evaluated at 24°C, atmospheric pressure, and at different percentages of relative humidity (RH). RH values in the 0–57% range had no significant effect on oxygen transmission rate (OTR); calculated OTR values ranged from 660 to 740 mL O2 (STP)/m2 24h atm. At 79% RH, the OTR doubled to 1,500 mL O2 (STP)/m2 24h atm. This effect correlated well with the moisture isotherm for the film which showed a low moisture content in the 0–57% RH range and a rapid increase at higher RH values. OTR values, particularly at high relative humidity, indicate no risk of developing anaerobic conditions on the food surface. 相似文献
139.
140.
简要介绍了各种正在研究开发中的天然气制合成气技术,催化部分氧化制合成气较好的工业化应用前景。对此过程中采用的催化剂和反应器也进行了介绍。 相似文献