全文获取类型
收费全文 | 8629篇 |
免费 | 136篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 74篇 |
综合类 | 5篇 |
化学工业 | 1096篇 |
金属工艺 | 113篇 |
机械仪表 | 207篇 |
建筑科学 | 233篇 |
矿业工程 | 33篇 |
能源动力 | 188篇 |
轻工业 | 527篇 |
水利工程 | 47篇 |
石油天然气 | 12篇 |
武器工业 | 2篇 |
无线电 | 639篇 |
一般工业技术 | 1173篇 |
冶金工业 | 3670篇 |
原子能技术 | 118篇 |
自动化技术 | 634篇 |
出版年
2021年 | 64篇 |
2020年 | 51篇 |
2019年 | 52篇 |
2018年 | 59篇 |
2017年 | 69篇 |
2016年 | 71篇 |
2015年 | 59篇 |
2014年 | 106篇 |
2013年 | 237篇 |
2012年 | 160篇 |
2011年 | 254篇 |
2010年 | 180篇 |
2009年 | 185篇 |
2008年 | 212篇 |
2007年 | 208篇 |
2006年 | 216篇 |
2005年 | 152篇 |
2004年 | 168篇 |
2003年 | 158篇 |
2002年 | 141篇 |
2001年 | 144篇 |
2000年 | 135篇 |
1999年 | 214篇 |
1998年 | 1043篇 |
1997年 | 578篇 |
1996年 | 465篇 |
1995年 | 289篇 |
1994年 | 252篇 |
1993年 | 287篇 |
1992年 | 120篇 |
1991年 | 125篇 |
1990年 | 124篇 |
1989年 | 126篇 |
1988年 | 108篇 |
1987年 | 117篇 |
1986年 | 114篇 |
1985年 | 118篇 |
1984年 | 104篇 |
1983年 | 89篇 |
1982年 | 88篇 |
1981年 | 124篇 |
1980年 | 110篇 |
1979年 | 93篇 |
1978年 | 86篇 |
1977年 | 150篇 |
1976年 | 254篇 |
1975年 | 79篇 |
1974年 | 47篇 |
1973年 | 68篇 |
1972年 | 46篇 |
排序方式: 共有8771条查询结果,搜索用时 15 毫秒
111.
BV Venkataraman S Dutt J Czekajewski L Nennerfelt C Williams 《Canadian Metallurgical Quarterly》1995,39(3):283-286
A simple method has been developed for continuous monitoring of metabolic activity of an isolated, perfused rat heart by O2/CO2 respirometer. Since respirometer provides vital data on oxygen consumption and carbon dioxide production of a preserved organ on a continuous basis over a long period of time, it will be possible to use this method to monitor viability of not only isolated heart but also any given donor organ under preservation. 相似文献
112.
JD Wagner L Zhang JK Williams TC Register DM Ackerman B Wiita TB Clarkson MR Adams 《Canadian Metallurgical Quarterly》1996,16(12):1473-1480
OBJECTIVES: To assess retinal complications and to identify risk factors for retinal complications following aqueous shunt procedures. MATERIALS AND METHODS: Records of 38 consecutive aqueous shunt procedures that were performed on 36 patients at the Eye Institute of the Medical College of Wisconsin, Milwaukee, from June 1993 to March 1995 (minimum follow-up, 6 months) were reviewed. The mean +/- SD follow-up was 11.4 +/- 5.2 months (median, 10.5 months). RESULTS: Twelve patients (32%) had the following retinal complications: 4 serous choroidal effusions (10%) that required drainage, 3 suprachoroidal hemorrhages (8%), 2 vitreous hemorrhages (5%), 1 rhegmatogenous retinal detachment (3%), 1 endophthalmitis (3%), and 1 scleral buckling extrusion (3%). Surgical procedures for retinal complications were required in 8 (67%) of these 12 patients. Visual acuity decreased 2 lines or more in 9 (75%) of these 12 patients. The median onset of a postoperative retinal complication was 12.5 days, with 10 patients (83%) experiencing complications within 35 days. Serous choroidal effusions developed in 10 other patients (26%), and these effusions resolved spontaneously. Visual acuity decreased 2 lines or more in 2 (20%) of these additional 10 patients. Patients who experienced serious retinal complications were significantly older, had a higher rate of hypertension, and postoperative ocular hypotony. Serious retinal complications were distributed evenly among patients with Krupin valves with discs and Molteno and Baerveldt devices. Experience with the Ahmed glaucoma valve implant was limited. CONCLUSION: Aqueous shunt procedures may be associated with significant retinal complications and subsequent visual loss. 相似文献
113.
Although memory disorders are frequently seen in survivors of brain injuries, remediation of patients with severe memory disorders is still relatively neglected in clinical practice due to pessimism by clinicians regarding the efficacy of such remediation. With respect to memory journal training, a further reason for this neglect is likely the lack of readily accessible protocols that therapists can use to work with these patients. The purpose of the present paper is to describe a new memory journal training protocol that was developed to teach brain injury survivors how to compensate for severe memory impairments by using three strengths of most brain injury survivors: immediate attention, procedural memory, and old learning. A training protocol is described that involves baseline testing and a needs assessment, five levels of training exercises, and discharge probe testing. It is concluded that patients with severely impaired memory abilities can learn the present system when care is taken to individualize journals, conduct proper needs assessments, and provide structured training exercises geared to the strengths of memory impaired persons. 相似文献
114.
115.
Ideas derived from the study of the process of crystallization may provide insights into molecular recognition in biological systems. Both processes exploit the cooperativity which arises from the formation of a large array of weak interactions. 相似文献
116.
Aeromagnetic compensation using neural networks 总被引:1,自引:0,他引:1
Peter M. Williams 《Neural computing & applications》1993,1(3):207-214
Airborne magnetic surveys in geophysical exploration can be subject to interference effects from the aircraft. Principal sources are the permanent magnetism of various parts of the aircraft, induction effects created by the earth's magnetic field and eddy-current fields produced by the aircraft's manoeuvres. Neural networks can model these effects as functions of roll, pitch, heading and their time derivatives, together with vertical acceleration, charging currents to the generator, etc., without assuming an explicit physical model. Separation of interference effects from background regional and diurnal fields can also be achieved in a satisfactory way. 相似文献
117.
It was for the first time that of the fifth year of monitoring of Plantago lanceolata L., reproduced within the thirty-kilometer zone of Chernobyl NPP disaster, the authors discovered high incidence of seedlings with various morphological abnormalities. It is suggested that the damages observed are related to the cumulative effect of radiation. 相似文献
118.
GC Borgia P Fantazzini C Palmonari G Timellini 《Canadian Metallurgical Quarterly》1996,14(7-8):899-901
NMR Relaxation and Imaging have been applied to study preparation processes of ceramic porous samples. Relaxation analysis gives a clear characterization of the materials, with high sensitivity. Differences in the method of preparation and steps as low as 25 degrees C in the firing temperatures are well detectable. Furthermore, the images permit distinguishing the different samples. The effects of the contrast in relaxation times dominate those due to the different porosities of the samples. Scanning Electron Microscopy confirms the interpretation that the changes in relaxation times are due to different pore space structures associated with the different firing temperatures. The higher the firing temperature, the larger are the pores and the higher is the amount of compact, sintered matrix, leading to higher relaxation times. 相似文献
119.
PURPOSE: The purpose of this research is to obtain the tablet coating distribution from weight distributions of uncoated and coated tablets. METHODS: The method of deconvolution with digital smoothing was used to calculate the distribution of coating applied to a tablet population from separate random measurements of individual uncoated and coated tablets. RESULTS: It was demonstrated that the calculated coating weight distribution agrees well with the measured distribution. The effect of the smoothing factor on the solution is illustrated. CONCLUSIONS: This method can be used during development to facilitate process scale-up/optimization. In routine production, the method can assess the reproducibility and consistency of a coating process. 相似文献
120.
Activation of auditory cortex during silent lipreading 总被引:1,自引:0,他引:1
GA Calvert ET Bullmore MJ Brammer R Campbell SC Williams PK McGuire PW Woodruff SD Iversen AS David 《Canadian Metallurgical Quarterly》1997,276(5312):593-596
Watching a speaker's lips during face-to-face conversation (lipreading) markedly improves speech perception, particularly in noisy conditions. With functional magnetic resonance imaging it was found that these linguistic visual cues are sufficient to activate auditory cortex in normal hearing individuals in the absence of auditory speech sounds. Two further experiments suggest that these auditory cortical areas are not engaged when an individual is viewing nonlinguistic facial movements but appear to be activated by silent meaningless speechlike movements (pseudospeech). This supports psycholinguistic evidence that seen speech influences the perception of heard speech at a prelexical stage. 相似文献