全文获取类型
收费全文 | 772篇 |
免费 | 5篇 |
专业分类
化学工业 | 6篇 |
金属工艺 | 6篇 |
机械仪表 | 1篇 |
建筑科学 | 1篇 |
轻工业 | 8篇 |
水利工程 | 1篇 |
无线电 | 7篇 |
一般工业技术 | 15篇 |
冶金工业 | 719篇 |
原子能技术 | 4篇 |
自动化技术 | 9篇 |
出版年
2023年 | 1篇 |
2021年 | 2篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2003年 | 3篇 |
2002年 | 28篇 |
2001年 | 32篇 |
2000年 | 9篇 |
1999年 | 21篇 |
1998年 | 204篇 |
1997年 | 96篇 |
1996年 | 64篇 |
1995年 | 42篇 |
1994年 | 22篇 |
1993年 | 34篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 14篇 |
1976年 | 44篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1955年 | 3篇 |
1939年 | 2篇 |
1930年 | 1篇 |
1929年 | 1篇 |
1923年 | 2篇 |
排序方式: 共有777条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
WK Halford 《Canadian Metallurgical Quarterly》1998,18(6):613-633
Behavioral couples therapy (BCT) was first described thirty years ago, and the conceptual basis of the approach has been evolving ever since. Whilst BCT in its current form is a well established treatment for relationship problems, there are significant limitations to its efficacy, and there are a number of new developments intended to enhance the efficacy of the approach. Currently BCT primarily is a skills training therapy, targeting change in couple's interactions to promote greater relationship satisfaction. Current developments focus on broadening this traditional emphasis on changing couple interactions to greater attention to reducing negative emotional responses to partner behaviors (increasing acceptance), and increasing self-directed personal change efforts. Future developments of BCT are likely to pay greater attention to different types of couple interaction which are associated with sustained relationship satisfaction, the individual vulnerabilities partners bring to relationships, and the environmental stresses impinging upon the couple. 相似文献
35.
36.
37.
To investigate whether abnormally accumulated betaAPP may be responsible for denervation of muscle fibers that are present in hereditary inclusion-body myopathy (h-IBM) and sporadic inclusion-body myositis (s-IBM), we cultured five h-IBM and eight normal muscle biopsies. In eight other experiments, a 3 kb human 751-betaAPP-cDNA was transferred, using adenovirus vector, into cultured normal myotubes immediately after myoblast fusion. In all experiments, cultured muscle fibers were co-cultured with fetal rat spinal cord. Controls had no detectable betaAPP epitopes, whereas betaAPP epitopes were greatly increased in cultured h-IBM muscle and in cultured normal muscle after betaAPP-gene transfer. Innervated normal cultured muscle fibers were continuously contracting and fully cross-striated, and they had acetylcholine receptors (AChRs) and acetylcholinesterase (AChE) accumulated only at the neuromuscular junctions (NMJs). By contrast, both groups of betaAPP-overexpressing cultured muscle fibers were not contracting and not cross-striated; and did not have NJMs containing AChRs and AChE. Our results suggest that over-expression of betaAPP in cultured muscle fibers inhibits their innervation, and that the accumulation of betaAPP in muscle fibers of both h- and s-IBM patients may be responsible for their not becoming or remaining properly innervated or reinnervated, i.e. a 'myogenous-dysinnervation' mechanism. 相似文献
38.
HY Dou JC Wu WL Peng C Chang WK Chi YD Chu CP Hu 《Canadian Metallurgical Quarterly》1998,5(6):428-434
Polyvinyl siloxane impression materials have applications in a variety of indirect procedures in prosthodontics and restorative dentistry. Favourable handling properties, good patient acceptance and excellent physical properties have resulted in their popularity in today's practice. In this review, the chemistry and important physical properties of polyvinyl siloxanes are summarized, and recent clinical questions of improved hydrophilics, tray adhesives, disinfection, and glove-induced polymerization inhibition are addressed. 相似文献
39.
Local damage to reinforced concrete structures caused by impact of aircraft engine missiles Part 1. Test program, method and results 总被引:3,自引:0,他引:3
T. Sugano H. Tsubota Y. Kasai N. Koshika H. Ohnuma W.A. von Riesemann D.C. Bickel M.B. Parks 《Nuclear Engineering and Design》1993,140(3):387-405
Structural damage induced by an aircraft crashing into a reinforced concrete structure includes local damage caused by the deformable engines, and global damage caused by the entire aircraft. Local damage to the target may consist of spalling of concrete from its front face together with missile penetration into it, scabbing of concrete from its rear face, and perforation of missile through it. Until now, local damage to concrete structures has been mainly evaluated by rigid missile impact tests. Past research work regarding local damage caused by impact of deformable missiles has been limited. This paper presents the results of a series of impact tests of small-, intermediate-, and full-scale engine models into reinforced concrete panels. The purpose of the tests was to determine the local damage to a reinforced concrete structure caused by the impact of a deformable aircraft engine. 相似文献
40.
AM van Berkel C Boland WK Redekop JJ Bergman AK Groen GN Tytgat K Huibregtse 《Canadian Metallurgical Quarterly》1998,30(8):681-686
BACKGROUND AND STUDY AIMS: Clogging of biliary stents continues to be a major clinical problem. Different polymer materials may have different effects on clogging. In vitro studies have shown a direct relation between the frictional coefficient of a polymer and the amount of encrusted material. Teflon appeared to be the best polymer for biliary stents. Two different types of stents made of Teflon have been tested in clinical practice and showed favourable patency rates. However, a randomized trial has never been performed. We compared the patency of an Amsterdam-type polyethylene stent with a Teflon stent in a prospective randomized trial. PATIENTS AND METHODS: Between September 1995 and November 1996, 42 patients received a Teflon stent and 42 patients a polyethylene stent. All patients had a distal malignant biliary stricture without a previous drainage procedure. Diagnoses included carcinoma of the pancreas (n = 76), papilla (n = 1), bile duct (n = 5) and metastases (n = 2). The internal and external diameter (10 Fr), length (9 cm) and stent design (a straight stent with two side flaps and one side hole at each end) were similar for both stents. RESULTS: A reduction in bilirubin of more than 20% within one week was seen in 91% of the patients. Early complication rates were similar in both groups (10%). The median follow-up was 142 days. Stent dysfunction occurred in 28 Teflon and 29 polyethylene stents. The thirty-day mortality was 14% in both groups. Patient survival did not differ significantly between the groups (median survival: Teflon 165 days, polyethylene 140 days). The median stent patency was 83 days for Teflon and 80 days for polyethylene stents, and was not significantly different either. CONCLUSION: Teflon material did not improve patency in biliary stents with an Amsterdam-type design. 相似文献