全文获取类型
收费全文 | 6173篇 |
免费 | 101篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 51篇 |
综合类 | 1篇 |
化学工业 | 542篇 |
金属工艺 | 70篇 |
机械仪表 | 67篇 |
建筑科学 | 124篇 |
矿业工程 | 4篇 |
能源动力 | 93篇 |
轻工业 | 287篇 |
水利工程 | 21篇 |
石油天然气 | 4篇 |
无线电 | 360篇 |
一般工业技术 | 611篇 |
冶金工业 | 3394篇 |
原子能技术 | 47篇 |
自动化技术 | 600篇 |
出版年
2022年 | 22篇 |
2021年 | 26篇 |
2019年 | 34篇 |
2018年 | 44篇 |
2017年 | 49篇 |
2016年 | 34篇 |
2015年 | 40篇 |
2014年 | 76篇 |
2013年 | 184篇 |
2012年 | 77篇 |
2011年 | 120篇 |
2010年 | 106篇 |
2009年 | 104篇 |
2008年 | 110篇 |
2007年 | 124篇 |
2006年 | 92篇 |
2005年 | 83篇 |
2004年 | 83篇 |
2003年 | 98篇 |
2002年 | 87篇 |
2001年 | 91篇 |
2000年 | 86篇 |
1999年 | 172篇 |
1998年 | 1087篇 |
1997年 | 575篇 |
1996年 | 397篇 |
1995年 | 249篇 |
1994年 | 205篇 |
1993年 | 238篇 |
1992年 | 78篇 |
1991年 | 81篇 |
1990年 | 78篇 |
1989年 | 80篇 |
1988年 | 83篇 |
1987年 | 91篇 |
1986年 | 53篇 |
1985年 | 54篇 |
1984年 | 61篇 |
1983年 | 58篇 |
1982年 | 48篇 |
1981年 | 57篇 |
1980年 | 80篇 |
1979年 | 58篇 |
1978年 | 44篇 |
1977年 | 83篇 |
1976年 | 192篇 |
1975年 | 46篇 |
1974年 | 33篇 |
1972年 | 24篇 |
1966年 | 22篇 |
排序方式: 共有6276条查询结果,搜索用时 15 毫秒
1.
2.
Lewis Gloria J.; Greenburg Sharon L.; Hatch David B. 《Canadian Metallurgical Quarterly》1988,19(1):81
We report the results of the first national survey of psychologists in private practice regarding their participation in peer consultation groups. The sample (71% return) was drawn from 800 randomly selected psychologists listed in the National Register of Health Service Providers in Psychology. We found that 23% of the sample currently belonged to peer consultation groups, and 24% had belonged in the past. Of those not currently in groups, 61% expressed the desire to belong if one were available. There were virtually no significant demographic differences between current members and nonmembers. We examined the following group characteristics: formation, length of existence, size, membership, leadership, theoretical orientation, range of experience, time and place, content, and group process. Groups tended to be small, informal, and leaderless; however, we found great variation among groups on all dimensions. Findings also showed a high degree of satisfaction with membership. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
CL Mesh BL Cmolik DW Van Heekeren JH Lee D Whittlesey LM Graham AS Geha SJ Bowlin 《Canadian Metallurgical Quarterly》1997,11(6):612-619
A premise of cardiac risk stratification is that the added risk of coronary artery bypass grafting (CABG) is offset by the improved safety of subsequent vascular reconstruction (VR). We questioned if elective CABG is patients with severe peripheral vascular disease (PVD) is a relatively high-risk procedure. A cohort study of 680 elective CABG patients from January 1993 to December 1994 was performed using three mutually exclusive outcomes of complication-free survival, morbidity, and mortality. Patient characteristic, operative, and outcome data were prospectively collected. Retrospective review determined that 58 patients had either a standard indication for or a history of VR. Overall CABG mortality was 2.5%, with statistically similar but relatively higher rates for PVD as compared to non-PVD patients. In contrast, major morbidity occurred at rates 3.6-fold higher in PVD patients (39.7%) than in disease-free patients (16.7%) after adjustment for the effects of patient and operative variables (odds ratio [OR] 3.67, 95% confidence interval [CI] 1.93-6.99). CABG morbidity in the PVD patient was most likely in those patients with aortoiliac (OR 9.51, CI 3.20-28.27) and aortic aneurysmal (OR 5.24, CI 1.28-21.41) disease types. CABG in PVD patients is associated with significant major morbidity. Such morbidity may preclude or alter the timing of subsequent VR. 相似文献
4.
BB Horswell CL Castiglione AE Poole LA Assael 《Canadian Metallurgical Quarterly》1993,51(2):145-9; discussion 149-50
The double-reversing Z-plasty of Furlow for closure of the soft palate was used in 34 children with various types of cleft palate. Mean age at repair was 12.8 months. Intraoperative experience was favorable, with acceptable operating time and blood loss. Length of hospitalization averaged 1.9 days. Postoperatively, two children experienced temporary stridor, which resolved within 24 to 48 hours. One child had dehiscence of the hard palate (Von Lagenbeck repair) 4 weeks postoperatively, and three children developed small oronasal fistulae. Early speech evaluation demonstrated adequate soft palate mobility in 33 of 34 patients, with observable velopharyngeal function. Twelve children had mild velar compromise, with eight exhibiting slight nasal air escape. 相似文献
5.
Lewis V. McCarty Richard Donelson Robert f. Hehemann 《Metallurgical and Materials Transactions A》1991,22(1):969-974
A mathematical model describes the carburization kinetics of tungsten powders mixed with carbon and heated in hydrogen. It
is based on diffusion of carbon through a shell of WC growing into particles which are modeled as spheres. The activation
energy is 58 kcal/mole in the temperature range 1056 to 1833 °C. Hydrogen gas is important to transport carbon as methane
or acetylene, but increased hydrogen pressure increases the rate of carburization so little that an adsorbed species such
as CH probably controls the carbon concentration at the particle surface.
Formerly with the Lamp Metals Laboratory, deceased, was Professor of Metallurgy at Case Western Reserve University Cleveland
OH. 相似文献
6.
Terahertz (THz) imaging is rapidly developing. We present two new methods, based respectively on (a) a broadband thermal source (globar) and (b) a coherent, monochromatic source (optically-pumped THz laser). A room-temperature detector (Golay cell) is employed. Image quality is similar to that reported by others using more complex sources (quantum cascade lasers) and detectors (superconducting tunneling junctions). 相似文献
7.
Influence of ion bombardment on the properties and microstructure of unbalanced magnetron deposited niobium coatings 总被引:3,自引:0,他引:3
The effect of the ion bombardment to unbalanced magnetron deposited, approximately 1.5 and 4.5 μm thick, Nb coatings have been investigated as the bias voltage was varied from UB=−75 to −150 V. Increasing bias voltage increased the hardness of the coating from 4.5 to 8.0 GPa. This was associated with residual stress and Ar incorporation into the Nb lattice. Strong {110} texture developed in the samples deposited at low bias voltages, while beyond UB=−100 V a {111} texture became dominant. However, strong {111} texture was observed only with the thicker 3Nb coatings. Secondary electron microscopy investigation of the coating topography showed fewer defects in the thicker coatings. All coatings exhibited good corrosion resistance, with the thicker coatings clearly outperforming the thinner ones. Excessive bias voltages (UB=−150 V) was found to lead to poor adhesion and loss of corrosion resistance. 相似文献
8.
Ozone measurement based on the optical absorption of visible light at 603 nm using polymer optical fibres is investigated and tested. Comparisons with a commercial UV based sensor demonstrate the ability of the visible based sensor to measure high concentrations over a range 27-127 mg/litre. A resolution of 5 mg/litre is also demonstrated for this sensor. 相似文献
9.