全文获取类型
收费全文 | 4995篇 |
免费 | 183篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 74篇 |
综合类 | 8篇 |
化学工业 | 970篇 |
金属工艺 | 156篇 |
机械仪表 | 116篇 |
建筑科学 | 50篇 |
矿业工程 | 16篇 |
能源动力 | 308篇 |
轻工业 | 227篇 |
水利工程 | 36篇 |
石油天然气 | 20篇 |
无线电 | 664篇 |
一般工业技术 | 1163篇 |
冶金工业 | 726篇 |
原子能技术 | 34篇 |
自动化技术 | 636篇 |
出版年
2023年 | 77篇 |
2022年 | 100篇 |
2021年 | 178篇 |
2020年 | 147篇 |
2019年 | 127篇 |
2018年 | 173篇 |
2017年 | 158篇 |
2016年 | 188篇 |
2015年 | 110篇 |
2014年 | 185篇 |
2013年 | 414篇 |
2012年 | 218篇 |
2011年 | 235篇 |
2010年 | 198篇 |
2009年 | 269篇 |
2008年 | 179篇 |
2007年 | 129篇 |
2006年 | 128篇 |
2005年 | 111篇 |
2004年 | 99篇 |
2003年 | 101篇 |
2002年 | 88篇 |
2001年 | 69篇 |
2000年 | 66篇 |
1999年 | 71篇 |
1998年 | 145篇 |
1997年 | 108篇 |
1996年 | 120篇 |
1995年 | 83篇 |
1994年 | 83篇 |
1993年 | 80篇 |
1992年 | 59篇 |
1991年 | 69篇 |
1990年 | 68篇 |
1989年 | 47篇 |
1988年 | 46篇 |
1987年 | 45篇 |
1986年 | 42篇 |
1985年 | 47篇 |
1984年 | 31篇 |
1983年 | 25篇 |
1982年 | 26篇 |
1981年 | 35篇 |
1980年 | 20篇 |
1979年 | 30篇 |
1978年 | 30篇 |
1977年 | 27篇 |
1976年 | 33篇 |
1975年 | 15篇 |
1973年 | 13篇 |
排序方式: 共有5204条查询结果,搜索用时 31 毫秒
61.
Some batches of detonator housings made up of Chromium plated Zn–Al alloy were found in an extensively cracked condition after few months of storage at room temperature. An analysis of the failure showed that the cracks were due to intergranular corrosion facilitated by segregation of lead at the grain boundaries. Improper chromium plating further aggravated the corrosion problem. This failure case emphasises the need for strict control of chemical composition for components made from Zn–Al alloy and the process of Cr plating of the components. 相似文献
62.
Das Abhishek Ozdemir Serkan Memik Gokhan Zambreno Joseph Choudhary Alok 《Computer Architecture Letters》2008,7(1):5-8
As transistor feature sizes continue to shrink intothe sub-90nm range and beyond, the effects of process variationson critical path delay and chip yields have amplified. A commonconcept to remedy the effects of variation is speed-binning, bywhich chips from a single batch are rated by a discrete range offrequencies and sold at different prices. In this paper, we discussstrategies to modify the number of chips in different bins andhence enhance the profits obtained from them. Particularly, wepropose a scheme that introduces a small Substitute Cacheassociated with each cache way to replicate the data elementsthat will be stored in the high latency lines. Assuming a fixedpricing model, this method increases the revenue by as much as13.8% without any impact on the performance of the chips. 相似文献
63.
Provision of automated support for planning protocol-directed therapy requires a computer program to take as input clinical data stored in an electronic patient-record system and to generate as output recommendations for therapeutic interventions and laboratory testing that are defined by applicable protocols. This paper presents a synthesis of research carried out at Stanford University to model the therapy-planning task and to demonstrate a component-based architecture for building protocol-based decision-support systems. We have constructed general-purpose software components that (1) interpret abstract protocol specifications to construct appropriate patient-specific treatment plans; (2) infer from time-stamped patient data higher-level, interval-based, abstract concepts; (3) perform time-oriented queries on a time-oriented patient database; and (4) allow acquisition and maintenance of protocol knowledge in a manner that facilitates efficient processing both by humans and by computers. We have implemented these components in a computer system known as EON. Each of the components has been developed, evaluated, and reported independently. We have evaluated the integration of the components as a composite architecture by implementing T-HELPER, a computer-based patient-record system that uses EON to offer advice regarding the management of patients who are following clinical trial protocols for AIDS or HIV infection. A test of the reuse of the software components in a different clinical domain demonstrated rapid development of a prototype application to support protocol-based care of patients who have breast cancer. 相似文献
64.
The effectiveness of Cocos nucifera pollen extract immunotherapy (CPE-IT) was studied in 96 patients allergic to C. nucifera pollen. A placebo-controlled study was performed at random for a period of 6-12 months. The clinical status of the patients measured by the symptom-medication scores demonstrated that C. nucifera pollen-allergic patients had significant (p < 0.005) clinical improvement after CPE-IT in comparison to placebo treatment. Serological study resulted a significant reduction (p < 0.001) of specific IgE and significant elevation (p < 0.01) of specific IgG in post-therapeutic patients' sera which were correlated significantly (r = 0.45, p < 0.001); the changes of the above immunoglobulin levels in the placebo-treated patients were nonsignificant. However, there was no correlation between symptom-medication scores and changes in specific serum IgE or IgG levels. 相似文献
65.
66.
67.
McFee J.E. Ellingson R.O. Elliott J. Das Y. 《IEEE transactions on instrumentation and measurement》1996,45(1):153-158
An experimental instrument is described which explicitly estimates location of ferrous rods parallel to a plane of measurement by analyzing simultaneous magnetic field and position data. The instrument consists of a unit containing a fluxgate magnetometer, position sensor and signal-conditioning circuits, connected to a unit containing a microprocessor, displays and associated electronics. An operator scans the sensor unit over the measurement surface, and the microprocessor estimates location, rod length and diameter. Experiments to estimate the parameters of horizontal typical reinforcing rods under a horizontal plane showed that the axis position could be estimated with an error of less than 0.5 cm, the length with a precision of <5 cm (<3.5%) and the depth with a precision of <0.4 cm at depths of 8 to 18 cm. Estimation of rod diameter was unreliable due to the presence of substantial remanent magnetization 相似文献
68.
69.
A typical or conventional workstation for a repetitive drill press operation was evaluated and subsequently redesigned by incorporating the concepts and principles of work design and ergonomics. The production task comprised of drilling four holes on a prepared steel plate. A methods–time measurement (MTM) analysis was conducted to eliminate unnecessary motions and improve the necessary (work) motions involved in task performance. The specific features of the redesigned workstation were specially designed equipment (jig, fixture, etc.), a suitable adjustable chair, proper work height, a placement of tools/equipment within reach envelope, and a comprehensive operator training method. An experimental investigation was conducted to evaluate and test the redesigned workstation in terms of operator productivity (production quantity and quality output) and satisfaction. The increases in quantity (number of holes drilled) and quality (number of good holes drilled) output were 22 and 50%, respectively, for the redesigned workstation compared to the typical or conventional workstation. The high improvement in quality output (50%) could be attributed to the improved design of the jig and fixture and the comprehensive operator training method, which emphasizes the quality aspect of production output. The improvement in operator satisfaction (scores) were highly significant. This investigation has demonstrated the beneficial effect of a combined work design and ergonomics approach, especially for the redesign of a workstation for a repetitive drill press operation. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 395–410, 2007. 相似文献
70.