全文获取类型
收费全文 | 15926篇 |
免费 | 227篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 208篇 |
综合类 | 3篇 |
化学工业 | 2180篇 |
金属工艺 | 369篇 |
机械仪表 | 355篇 |
建筑科学 | 570篇 |
矿业工程 | 74篇 |
能源动力 | 338篇 |
轻工业 | 1283篇 |
水利工程 | 93篇 |
石油天然气 | 122篇 |
无线电 | 1558篇 |
一般工业技术 | 2396篇 |
冶金工业 | 4974篇 |
原子能技术 | 167篇 |
自动化技术 | 1487篇 |
出版年
2022年 | 90篇 |
2021年 | 110篇 |
2019年 | 120篇 |
2018年 | 144篇 |
2017年 | 113篇 |
2016年 | 105篇 |
2015年 | 116篇 |
2014年 | 246篇 |
2013年 | 624篇 |
2012年 | 330篇 |
2011年 | 433篇 |
2010年 | 357篇 |
2009年 | 355篇 |
2008年 | 480篇 |
2007年 | 462篇 |
2006年 | 453篇 |
2005年 | 411篇 |
2004年 | 336篇 |
2003年 | 375篇 |
2002年 | 326篇 |
2001年 | 333篇 |
2000年 | 330篇 |
1999年 | 407篇 |
1998年 | 1334篇 |
1997年 | 852篇 |
1996年 | 612篇 |
1995年 | 436篇 |
1994年 | 389篇 |
1993年 | 409篇 |
1992年 | 279篇 |
1991年 | 253篇 |
1990年 | 271篇 |
1989年 | 222篇 |
1988年 | 224篇 |
1987年 | 213篇 |
1986年 | 207篇 |
1985年 | 261篇 |
1984年 | 219篇 |
1983年 | 212篇 |
1982年 | 209篇 |
1981年 | 191篇 |
1980年 | 211篇 |
1979年 | 145篇 |
1978年 | 143篇 |
1977年 | 245篇 |
1976年 | 325篇 |
1975年 | 149篇 |
1974年 | 140篇 |
1973年 | 115篇 |
1970年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
Cinematic primitives for multimedia 总被引:5,自引:0,他引:5
The development of robust frameworks in interactive multimedia for representing story elements to the machine so that they can be retrieved in multiple contexts is addressed. Interactive multimedia is discussed as a user-directed form of storytelling, and the nature of cinematic storytelling is examined. It is proposed that content can be represented in layers. This model for layered information will allow programs to take advantage of the relation between cinematic sequences and the world they represent. The collection of content by the camera and microphone is considered in this context. The use of the methodology to build meaningful, context-rich sequences is discussed 相似文献
13.
Hydroelectric generators of less than 20 kilowatts can be in remote areas served only by a single-phase line. For high efficiency and low cost, a three-phase induction generator should be used. This three-phase generator can operate with balanced voltages and currents when the ``phase-splitting' circuit uses two capacitors connetted to two different single-phase voltage sources. 相似文献
14.
Bordini Ernest J.; Tucker Jalie A.; Vuchinich Rudy E.; Rudd Edmund J. 《Canadian Metallurgical Quarterly》1986,95(4):346
Assessed whether women self-handicap with alcohol consumption prior to engaging in a social evaluation task, which may be more relevant to their self-esteem than the intellectual tasks used in past self-handicapping studies on substance use. 113 women (aged 19–32 yrs), who were evaluated as normal drinkers, performed either a solvable or an insolvable social judgment task and then received either success feedback or no feedback. Ss received access to alcoholic and nonalcoholic beverages while awaiting a retest. The study terminated before the retest. The self-handicapping hypothesis that noncontingent success would produce relatively greater alcohol consumption was not supported. Regardless of feedback, insolvable test Ss consumed more alcohol than did solvable test Ss. Findings suggest that the hypothesis may be limited as a general model of alcohol consumption in both sexes. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
15.
16.
Plastic deformation and fracture of binary TiAl-base alloys 总被引:4,自引:0,他引:4
The mechanical behavior of binary TiAl alloys containing 46 to 60 at. pct Al has been studied in bulk materials preparedvia rapid solidification processing. Bending and tensile tests were carried out at room temperature as a function of Al concentration.
A few alloys were also tested from liquid nitrogen temperature to ∼ 1000°C. Deformation substructures were studied by analytical
transmission electron microscopy and fracture modes by scanning electron microscopy (SEM). It was found that both microstructure
and composition strongly affect the mechanical behavior of TiAl-base alloys. A duplex structure, which contains both primary
y grains and transformedγ/α
2 lamellar grains, is more deformable than a single-phase or a fully transformed structure. The highest plasticities are observed
in duplex alloys containing 48–50 at. pct Al after heat treatment in the center of theγ + α phase field. The deformation of these duplex alloys is facilitated by 1/2[110] slip and {111} twinning, but very limited
superdislocation slip occurs. The twin deformation is suggested to result from a lowered stacking fault energy due to oxygen
depletion or an intrinsic change in chemical bonding. Other factors, such as grain size and grain boundary chemistry and structure,
are important from a fracture point of view. The results on the deformation and fracture modes as a function of test temperature
are also discussed. 相似文献
17.
Canham R.O. Smith S.L. Tyrrell A.M. 《Vision, Image and Signal Processing, IEE Proceedings -》2005,152(6):741-749
Complex and highly distorted line drawings are produced by subjects attempting the Rey Complex Figure test, a clinical test of neuropsychological assessment. However, the marking scheme conventionally employed can be subjective and unreliable. In this paper, the first stages in automating this scoring system are investigated using a robust technique to locate a reduced set of scoring sections and a knowledge-based system that employs spatial metrics and fuzzy approximation techniques. Testing the technique using clinical data produced encouraging results that support the argument that this is a feasible approach for implementing a fully automated system, and that in its current state, can be immediately applied in a semi-automated system. 相似文献
18.
A Notghi R Hutchinson D Kumar NB Smith LK Harding 《Canadian Metallurgical Quarterly》1994,35(7):976-981
Segmental colonic transit has been measured in 101 patients. Two MBq of 111Indium absorbed on resin pellets and encapsulated in an enteric coated capsule was given at 7 00 am. Hourly images during the first day, and three images during each subsequent day were acquired for up to three days. Using all scan and patient data the scans were categorised in one of the five patterns of colonic transit: normal, rapid, right delay, left delay, or generalised delay. The geometric centres and per cent activity at each time point was compared between the five groups of colonic transit patients to find the best time for imaging and so to distinguish the five groups. During the first day, early images did not help in diagnosis of patterns of transit, however, in the later images (six hours onwards after the ingestion of the activity) the rapid transit groups could be identified. Images at 27 and 51 hours were both required to distinguish all five groups of patients from each other. Only in the 'normal' transit patients was there some excretion of the activity during the course of the second day, otherwise there was no difference in the images taken in the course of a day (second or third day). A simplified protocol requires a minimum of three images to distinguish all five patterns of colonic transit. The activity should be ingested in the morning (7 00 am) and the first image taken at the end of the working day (8-10 hours after ingestion), the second image on the morning of the second day, and the third image during the course of the third day. This simple protocol would provide all the clinically relevant information necessary for correct classification of the colonic transit. 相似文献
19.
J Smith 《Canadian Metallurgical Quarterly》1993,306(6891):1524-1526