全文获取类型
收费全文 | 2112篇 |
免费 | 39篇 |
学科分类
工业技术 | 2151篇 |
出版年
2021年 | 36篇 |
2020年 | 25篇 |
2019年 | 27篇 |
2018年 | 22篇 |
2017年 | 20篇 |
2016年 | 39篇 |
2015年 | 35篇 |
2014年 | 43篇 |
2013年 | 91篇 |
2012年 | 67篇 |
2011年 | 99篇 |
2010年 | 71篇 |
2009年 | 78篇 |
2008年 | 87篇 |
2007年 | 74篇 |
2006年 | 79篇 |
2005年 | 55篇 |
2004年 | 50篇 |
2003年 | 49篇 |
2002年 | 58篇 |
2001年 | 46篇 |
2000年 | 29篇 |
1999年 | 47篇 |
1998年 | 97篇 |
1997年 | 64篇 |
1996年 | 56篇 |
1995年 | 50篇 |
1994年 | 46篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 16篇 |
1990年 | 37篇 |
1989年 | 21篇 |
1988年 | 35篇 |
1987年 | 34篇 |
1986年 | 28篇 |
1985年 | 29篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 27篇 |
1981年 | 12篇 |
1980年 | 25篇 |
1979年 | 13篇 |
1978年 | 16篇 |
1977年 | 26篇 |
1976年 | 30篇 |
1975年 | 15篇 |
1974年 | 15篇 |
1973年 | 13篇 |
1972年 | 10篇 |
排序方式: 共有2151条查询结果,搜索用时 15 毫秒
1.
2.
3.
Hook T.B. Brown J. Cottrell P. Adler E. Hoyniak D. Johnson J. Mann R. 《Electron Devices, IEEE Transactions on》2003,50(9):1946-1951
Lateral scattering of retrograde well implants is shown to have an effect on the threshold voltage of nearby devices. The threshold voltage of both NMOSFETs and PMOSFETs increases in magnitude for conventional retrograde wells, but for triple-well isolated NMOSFETs the threshold voltage decreases for narrow devices near the edge of the well. Electrical data, SIMS, and SUPREM4 simulations are shown that elucidate the phenomenon. 相似文献
4.
5.
In this work, we examine the effect of small additions of cationic quaternary ammonium salts (QAS) of different molecular weight on the rheology of an industrial ceramic suspension deflocculated with sodium polyacrylate and sodium metasilicate. The observed shear thinning behaviors obey the typical power law of fluid rheology. In order to characterize the rheological behavior of these slurries, three new parameters are introduced: a low shear rate consistency index and two transient viscosities, distant from the equilibrium, after increasing and decreasing the shear rates. These parameters vary with polyacrylate molecular weight and on additions of small quantities of QAS, which we found to be useful for decreasing the slurry viscosity. 相似文献
6.
Berrin-Wasserman Stacy; Winnick Wilma A.; Borod Joan C. 《Canadian Metallurgical Quarterly》2003,17(3):429
Does sentence generation and/or stimulus emotionality enhance verbal memory in patients with neurological impairment? This question was addressed by testing 40 patients with unilateral stroke (20 with left-brain and 20 with right-brain damage) and 20 healthy control participants for recall and recognition of 48 target words. During encoding, emotional and nonemotional words were either presented in sentences (read condition) or used to form sentences (generate condition). Both word emotionality and generative processing improved memory performance in all groups. The authors suggest that a similar influence (i.e., cognitive activation) underlies both of these memory-enhancing effects, although the putative origins of the 2 effects are quite different. Neuropsychological underpinnings and clinical implications of these phenomena are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Sood Johanna R.; Cisek Edward; Zimmerman Joan; Zaleski Ellen H.; Fillmore Herbert H. 《Canadian Metallurgical Quarterly》2003,48(1):44
Objective: To replicate and extend P. A. Lichtenberg and colleagues' (1996) cross-disciplinary intervention to improve physical and mental health among older adults. Participants: 14 depressed older adults (6 treatment, 8 control). Setting: The short-term rehabilitation unit of an urban nursing home. Intervention: Occupational therapists were trained to treat depression using pleasant events and cognitive-behavioral therapies. Outcome Measures: Geriatric Depression Scale, the Short Form-12, and the Multi-Level Assessment Instrument: Activities of Daily Living. Results: No significant group differences were found in physical or mental health. However, more control group members (75%) than treatment group members (33%) were depressed at study completion. Conclusions: The treatment of depressive symptoms can be integrated with a nonmental health treatment modality. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
8.
With the aid of automated reasoning techniques, we show that all previously known short single axioms for odd exponent groups are special cases of one general schema. We also demonstrate how to convert the proofs generated by an automated reasoning system into proofs understandable by a human.Authors supported by NSF Grant DMS-9100665 相似文献
9.
PURPOSE: The etiology of voiding dysfunction was determined in men after a cerebrovascular accident who were at risk for obstructive uropathy to evaluate whether the cause of voiding dysfunction could be predicted by the type (obstructive or irritative) or onset of symptoms. MATERIALS AND METHODS: We evaluated 38 men with complaints of voiding dysfunction following a cerebrovascular accident. All patients were of the age when bladder outlet obstruction secondary to benign prostatic hyperplasia would otherwise be prevalent. After a comprehensive history and physical examination, all patients underwent multichannel urodynamic studies at a medium fill rate (20 to 50 ml. per minute). Findings were classified by the Abrams-Griffiths nomogram as obstruction, no obstruction or equivocal. RESULTS: Mean patient age was 70 years (range 54 to 87). Patients were grouped according to the presenting voiding complaints (purely irritative in 42%, purely obstructive in 34% or mixed in 24%). In 34 patients (89%) the onset of symptoms paralleled the occurrence of the cerebrovascular accident. Detrusor hyperreflexia was noted in 82% of the patients. There was no statistically significant difference in the occurrence of detrusor hyperreflexia among the 3 symptom groups (Fisher's exact test). Pressure-flow analysis clearly showed obstruction in 24 patients (63%), no obstruction in 9 (24%) and equivocal results in 5 (13%) according to the nomogram. There was no statistically significant difference in the incidence of obstruction among the 3 symptom groups (Fisher's exact test). CONCLUSIONS: Presenting symptoms did not predict the urodynamic findings of bladder outlet obstruction or detrusor hyperreflexia. The significant incidence of onset of symptoms after stroke suggests that the cerebrovascular accident induced voiding dysfunction in the face of preexisting bladder outlet obstruction may exacerbate the symptoms of the latter condition or vice versa. 相似文献
10.
S Cohrs G Herrendorf J Wiltfang A Rodenbeck J Kinkelbur L Adler G Hajak 《Canadian Metallurgical Quarterly》1996,146(13-14):366-368
10 patients with obstructive sleep apnea syndrome (OSAS) have been treated with the new surgical procedure functional palatoraphy and modified genioplasty. 5 months after surgery 7 patients with an apnea hypopnea index under 10 were cured. Three therapy refractory patients were all overweight with a body mass index of more than 29 kg/m2. Excessively overweight patients should therefore not be operated. Following the selection criteria we introduced an effective new treatment method for OSAS. 相似文献