Author Keywords: power series; curve; surface; intersection problems; curve tracing; geometric continuity 相似文献
全文获取类型
收费全文 | 1773篇 |
免费 | 25篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 350篇 |
金属工艺 | 43篇 |
机械仪表 | 47篇 |
建筑科学 | 54篇 |
矿业工程 | 6篇 |
能源动力 | 34篇 |
轻工业 | 123篇 |
水利工程 | 15篇 |
石油天然气 | 22篇 |
武器工业 | 1篇 |
无线电 | 153篇 |
一般工业技术 | 236篇 |
冶金工业 | 380篇 |
原子能技术 | 11篇 |
自动化技术 | 310篇 |
出版年
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 17篇 |
2016年 | 27篇 |
2015年 | 14篇 |
2014年 | 40篇 |
2013年 | 92篇 |
2012年 | 53篇 |
2011年 | 63篇 |
2010年 | 47篇 |
2009年 | 43篇 |
2008年 | 56篇 |
2007年 | 69篇 |
2006年 | 64篇 |
2005年 | 50篇 |
2004年 | 57篇 |
2003年 | 49篇 |
2002年 | 50篇 |
2001年 | 46篇 |
2000年 | 56篇 |
1999年 | 58篇 |
1998年 | 77篇 |
1997年 | 56篇 |
1996年 | 53篇 |
1995年 | 43篇 |
1994年 | 46篇 |
1993年 | 32篇 |
1992年 | 34篇 |
1991年 | 26篇 |
1990年 | 34篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 15篇 |
1982年 | 10篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1979年 | 19篇 |
1978年 | 16篇 |
1976年 | 14篇 |
1975年 | 18篇 |
1974年 | 16篇 |
1973年 | 11篇 |
1972年 | 11篇 |
1970年 | 11篇 |
排序方式: 共有1800条查询结果,搜索用时 0 毫秒
41.
Results from wear studies in repetitive impact sliding are described in this paper. The material pair studied consisted of steel CPM-10V (specimen) (where CPM denotes crucible particle metallurgy) and 17-4 precipitationhardened (PH) steel (counterface) with transverse sliding velocities of 4 and 8 m s?1. By means of scanning electron microscopy, energy-dispersive analysis of X-rays and X-ray diffraction methods it is shown that the wear is due to a material transport of the counterface 17-4 PH steel to the CPM-10V surface. In the wear process, a change in microhardness of the counterface substrate is apparent, and X-ray diffraction of debris confirms the presence of transformed metal. These products include γ-Fe together with trace amounts of α-Fe2O3; however, virtually no carbide from the CPM-10V steel was detected. 相似文献
42.
J Wayne H Suh Z Misulovin KA Sokol K Inaba MC Nussenzweig 《Canadian Metallurgical Quarterly》1994,1(2):95-107
Effects of etoposide (VP-16) and cytosine arabinoside (Ara-C) on the cell cycle of HL-60 and THP-1 cells were studied by flow cytometry using the bromodeoxyuridine (BrdU)/DNA assay technique to investigate the efficacy of VP-16 for monocytic leukemia cells. VP-16 inhibited the proliferation of THP-1 cells more strongly than that of HL-60 cells at any concentrations used at 24 and 48 hr. VP-16 arrested HL-60 and THP-1 cells in the G2/M phase and reduced them in the G0/G1 and early S phase at higher concentrations. There was no significant difference in the percentage of G2/M phase cells at the same concentration between both cells. However, reduction in the G0/G1 and early S phase cells was more marked in THP-1 than HL-60 cells significantly. On the other hand, Ara-C perturbed the cell cycle of HL-60 cells more than that of THP-1 cells at 24 and 48 hr. These results suggest that the effects of VP-16 on the cell cycle may be more intense in THP-1 than HL-60 cells, and support the efficacy of VP-16 for treating monocytic leukemia in vivo. 相似文献
43.
Applications of power series in computational geometry 总被引:2,自引:0,他引:2
A number of algorithms are presented for obtaining power series expansions of curves and surfaces at a point. Some results on the radius of convergence are given. Two applications of series are given:
1. • for curve tracing algorithms, where a truncated series is used to approximate the curve of intersection of two surfaces
2. • to define nth degree geometric continuity, for arbitrary
44.
The mechanical properties of many materials have been enhanced via cryogenic treatment, which is a cold temperature process performed after traditional heat treatment. In this research the effect of cryogenic treatment on GRCop-84 was examined. Cryogenically and non-cryogenically treated samples were tested identically to determine whether cryogenic treatment has a significant affect on the thermal conductivity of GRCop-84. Optical and electron microscopy were used to characterize the material properties. Cryogenic treatment includes a temper that appears to be responsible for the enhancements observed in GRCop-84. 相似文献
45.
Scott R Boss Laurie J Kirsch Ingo Angermeier Raymond A Shingler R Wayne Boss 《欧洲信息系统杂志》2009,18(2):151-164
Information security has become increasingly important to organizations. Despite the prevalence of technical security measures, individual employees remain the key link – and frequently the weakest link – in corporate defenses. When individuals choose to disregard security policies and procedures, the organization is at risk. How, then, can organizations motivate their employees to follow security guidelines? Using an organizational control lens, we build a model to explain individual information security precaution-taking behavior. Specific hypotheses are developed and tested using a field survey. We examine elements of control and introduce the concept of ‘mandatoriness,’ which we define as the degree to which individuals perceive that compliance with existing security policies and procedures is compulsory or expected by organizational management. We find that the acts of specifying policies and evaluating behaviors are effective in convincing individuals that security policies are mandatory. The perception of mandatoriness is effective in motivating individuals to take security precautions, thus if individuals believe that management watches, they will comply. 相似文献
46.
47.
The prevalence of Campylobacter (>90%) and Salmonella (33%) in turkeys at slaughter has been estimated. This report describes studies to estimate the time of entry of Campylobacter and Salmonella into the brooder house, which is the first stage of commercial turkey production. In trial 1, birds (∼100 per time point) were monitored by conventional culture at three intervals (0, 9, and 16 days of age). Campylobacter spp. were not detected in poults at the day of hatch; Salmonella was isolated from the ceca (3.9%) and yolk sac (0.1%). By day 9, Salmonella were frequently isolated from the ceca (55%) and small intestine (45%) while Campylobacter was not cultured. By day 16, the prevalence of Salmonella in the ceca (21%) and small intestine (5.1%) had declined; Campylobacter was infrequently isolated from either the ceca (2%) or small intestine (3%). In trial 2, poults (50 per time point at 5, 20, and 33 days of age) were monitored for Campylobacter and Salmonella by real-time polymerase chain reaction (PCR); Salmonella was also monitored by conventional culture. Whereas Campylobacter was not detected by real-time PCR in the ceca of 5-day-old birds, it was detected on days 20 (92%) and 33 (90%). In contrast, Salmonella was isolated from young birds at days 5 (98%), 20 (98%), and 33 (98%), after which time the turkeys were moved to the finisher house. At slaughter at 138 days, Salmonella prevalence in the ceca had declined (4.5%) in contrast to the prevalence of Campylobacter (92%). Antimicrobial sensitivity profiles of the Salmonella isolates indicated an increase of sulfonamide-resistant isolates throughout the brooder stage. Genotyping by pulsed-field gel electrophoresis analysis of Salmonella (45 isolates per sampling time) indicated fluctuating populations as the birds matured. 相似文献
48.
49.
Peter Lloyd Woodfield Andrew Seagar Wayne Hall 《International Journal of Thermophysics》2012,33(2):259-278
Vibrating wire viscometers rely on the principle that the viscosity of the fluid surrounding the wire provides the dominant damping action on the motion of the wire. However, some residual damping is always present due to other effects such as internal friction of the wire (anelastic relaxation), losses through the wire supports, and magnetic damping. Magnetic damping is a physical mechanism that has received relatively less attention than internal friction in the context of viscometers. The phenomenon arises because the current induced by the motion of the wire contributes to the magnetic field in such a way as to oppose its own motion. For a test circuit using a 40 μm diameter tungsten wire in a 0.3 T magnetic field, surprisingly, the effect of magnetic damping was found to be of a similar order of magnitude to other non-viscous damping effects. The effect can be accounted for by including the internal impedance of the oscillating voltage source in the model and it disappears completely for a perfect oscillating current source. 相似文献
50.
Srinivasan Arjun Tekalur Arun Shukla Martin Sadd K. Wayne Lee 《Construction and Building Materials》2009,23(5):1795-1802
There are various methods to determine the compressive and tensile strength of asphalt concrete under static loading conditions and most studies on asphalt strength and fracture have been conducted under such loading conditions. However, pavement materials also have to withstand a wide variety of loading and temperature conditions which may vary from quasi-static to high-strain rate impact, and pavement breakdown may occur due to fracture and/or fatigue failure. In the present study, a bituminous mix with 30% RAP has been characterized under quasi-static (10?3–10?4 strain/s) and high-strain rate (200–700 strain/s) regimes. The experimental studies have been performed to better understand the compressive, tensile and fracture response of bituminous mixes. Split Hopkinson pressure bar (SHPB) and its modifications were used for high-strain rate characterization of this bituminous mixture. It was observed that the mechanical properties of the hot mix asphalt (HMA) changed significantly under high-strain rate testing. Also, the failure mechanisms observed under the high-strain rate loading were found to be considerably different from those obtained in static testing, where failure of binder was a predominant mechanism. It was observed that high-strain rate loading caused trans-aggregate failures in the specimens; in addition to failure of the binder. 相似文献