全文获取类型
收费全文 | 448篇 |
免费 | 9篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 156篇 |
金属工艺 | 3篇 |
机械仪表 | 21篇 |
建筑科学 | 22篇 |
矿业工程 | 1篇 |
能源动力 | 8篇 |
轻工业 | 24篇 |
水利工程 | 2篇 |
无线电 | 42篇 |
一般工业技术 | 70篇 |
冶金工业 | 39篇 |
原子能技术 | 4篇 |
自动化技术 | 62篇 |
出版年
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 31篇 |
2012年 | 33篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 21篇 |
2007年 | 30篇 |
2006年 | 17篇 |
2005年 | 21篇 |
2004年 | 8篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有457条查询结果,搜索用时 15 毫秒
31.
C. Charles Chen Gabor Kaszas Judit E. Puskas Joseph P. Kennedy 《Polymer Bulletin》1989,22(5-6):463-470
Mono- and bifunctionaltert-alcohols, i.e., cumyl alcohol (CumOH), 2,4,4-trimethyl-2-pentanol (TMPOH), 2,6-dihydroxy-2,4, 4, 6-tetramethylheptane (TMHDiOH), in conjunction with BCl3 have been shown to be efficient initiating systems for the living polymerization of isobutylene (IB) in CH3Cl or CH2Cl2 solvents in the –10° to –80°C range. The living nature of the polymerizations was demonstrated by linear Mn versus amount of polyisobutylene (PIB) formed (WPIB) plots starting at the origin and corresponding horizontal number of PIB moles formed (N) versus WPIB plots. Quenching with methanol producestert-chlorine terminated PIBs. Quantitative dehydrochlorination of the latter products yields exo-olefin (isopropylidene) end groups. These experiments demonstrate that living carbocationic polymerizations have in fact been conducted in these laboratories long ago (1) without having been recognized as such. 相似文献
32.
Kabacoff Robert I.; Miller Ivan W.; Bishop Duane S.; Epstein Nathan B.; Keitner Gabor I. 《Canadian Metallurgical Quarterly》1990,3(4):431
Investigated the psychometric properties of the McMaster Family Assessment Device (FAD [N. Epstein et al; see PA, Vol 71:2891]), a multidimensional measure of family functioning, using data from psychiatric (n?=?1,138), nonclinical (n?=?627), and medical (n?=?298) samples. Internal scale reliabilities and factorial validity were assessed for each group, and results were compared across groups. In general, scale reliabilities were favorable and the hypothesized factor structure of the FAD was supported. Results also support the use of the 60-item version over the original 53-item version. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
Michael Jeserich Bela Merkely Pascal Schlosser Simone Kimmel Gabor Pavlik Stephan Achenbach 《Magma (New York, N.Y.)》2017,30(3):309-316
Objective
To evaluate three-dimensional T2-weighted fast spin echo triple inversion recovery sequences (STIR+) for the diagnosis of myocardial edema in patients with suspected early myocarditis after respiratory or gastrointestinal tract viral infection and at follow-up.Materials and methods
We prospectively examined 28 patients with suspected myocarditis and 37 controls matched for gender and age. An ECG-triggered STIR+ was used to cover the entire left ventricle in short-axis images with 10-mm slice thickness and no interslice gap. The global signal intensity ratio (heart muscle in relation to skeletal muscle) was calculated (global STIR+ ratio) to evaluate edema. All patients had repeat examinations at follow-up (mean interval 4.9 months, 1–12 months).Results
The mean global STIR+ ratio was 2.15 ± 0.4 in the initial examination of patients as compared to 1.78 ± 0.3 in controls (p < 0.0001) and 1.89 ± 0.3 in patients at follow-up (p = 0.0001 vs. first visit). Left ventricular ejection fraction did not differ between patients and controls at baseline and at follow-up.Conclusion
We could identify a significantly higher global STIR+ ratio in patients with suspected myocarditis compared to controls, and a dynamic change during follow-up. The global STIR+ ratio may, therefore, be useful for the diagnosis of myocarditis and should be further explored.34.
35.
36.
T. Petrisor Jr. R. B. Mos M. Nasui M. S. Gabor A. Augieri G. Celentano D. De Felicis E. Bemporad L. Ciontea T. Petrisor 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2493-2500
In the present paper, we analyze the role of in situ grown BaZrO3 (BZO) inclusions in YBa2Cu3O7?x (YBCO) thin films prepared by chemical solution deposition using a low fluorine coating solution, on the field angle dependence of the critical current density, J c (??), data using the vortex path model. In order to form a coherent picture on the BZO doping influence on the pinning properties of the YBCO matrix, detailed structural analyses performed by X-ray diffraction techniques and microstructural evaluation by transmission electron microscopy are also presented. The evaluation of different contributions to the overall, J c , permitted us to prove the effectiveness of the BZO inclusions acting as isotropic pinning centers, reflected in a uniform component of high relative value with respect to other components. For the studied 10 mol % BZO doping concentration, a threefold increase in the critical current density, J c , of the YBCO host is measured, in self-field at 77 K, corresponding to a value of J c =2.9MA/cm2, whereas a factor 10 is measured at 1 T (J c =0.35 MA/cm2). 相似文献
37.
Hirokazu Yoshizawa Gabor C. Temes 《IEEE transactions on circuits and systems. I, Regular papers》2007,54(1):193-199
This paper describes high-precision switched-capacitor (SC) track-and-hold amplifier (THA) stages. They use a novel continuous-time correlated double sampling (CDS) scheme to desensitize the operation to amplifier imperfections. Unlike earlier predictive-CDS amplifiers, the circuits do not need a sampled-and-held input signal for their operation. During the tracking period, an auxiliary continuous-time signal path is established, which predicts the output voltage during the holding period. This allows accurate operation even for low amplifier gains and large offsets over a wide input frequency range. Extensive simulations were performed to compare the performance of the proposed THAs with earlier circuits utilizing CDS. The results verify that their operation is far more robust than that of any previously described SC amplifiers 相似文献
38.
Oxide layers were grown on tubular samples of Zr–1%Nb under conditions simulating those in VVER-type pressurised water reactors, viz. in near-neutral borate solutions in an autoclave at 290 °C. These samples were investigated using electrochemical impedance spectroscopy which was found to be suitable to follow in situ the corrosion process. A –CPEoxRox– element was used to characterise the oxide layer on Zr–1%Nb. Both the CPEox coefficient, σox, and the parallel resistance, Rox, were found to be thickness dependent. The layer thickness, however, can only be calculated after a calibration procedure. The temperature dependence of the CPEox element was also found to be anomalous while the temperature dependence of Rox indicates that the oxide layer has semiconductor properties. The relaxation time – defined as (Roxσox)1/ – was found to be quasi-independent of oxidation time and temperature; thus it is characteristic to the oxide layer on Zr–1%Nb. 相似文献
39.
40.
Songfeng Guo Garrett G Grindle Erica L Authier Rory A Cooper Shirley G Fitzgerald Annmarie Kelleher Rosemarie Cooper 《IEEE transactions on neural systems and rehabilitation engineering》2006,14(1):83-90
Increased physical activity is important for reducing the risk of cardiovascular disease. However, among people with disabilities, inactivity is prevalent. In order to encourage exercise among members of this group, an exercise system combining arm ergometry with video gaming, called the GAME(Cycle) was previously developed. User input was received through an arm crank ergometer on a swivel, with the angular velocity of the ergometer resistance wheel controlling one axis and rotation of ergometer about the swivel controlling the other. The purpose of this study was to detail the algorithms used in this device and present novel features included in a second generation of the GAME(Cycle). The features include a wheel on base, a steering return mechanism, and wireless fire buttons. A focus group of clinicians (n = 8), wheelchair users (n = 8), and clinician wheelchair users (n = 2) was conducted to evaluate the features of the GAME(Cycle). The focus group suggested improvements to the steering mechanism and to reduce vibration in the system. However, the focus group enjoyed the GAME(Cycle) and felt that it would encourage exercise among persons with disabilities. 相似文献