全文获取类型
收费全文 | 864篇 |
免费 | 22篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 11篇 |
综合类 | 1篇 |
化学工业 | 276篇 |
金属工艺 | 36篇 |
机械仪表 | 12篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 24篇 |
轻工业 | 42篇 |
水利工程 | 4篇 |
无线电 | 71篇 |
一般工业技术 | 159篇 |
冶金工业 | 114篇 |
原子能技术 | 6篇 |
自动化技术 | 113篇 |
出版年
2023年 | 3篇 |
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 24篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 11篇 |
2016年 | 39篇 |
2015年 | 14篇 |
2014年 | 30篇 |
2013年 | 44篇 |
2012年 | 27篇 |
2011年 | 43篇 |
2010年 | 32篇 |
2009年 | 47篇 |
2008年 | 37篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 27篇 |
2004年 | 15篇 |
2003年 | 23篇 |
2002年 | 26篇 |
2001年 | 25篇 |
2000年 | 26篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 18篇 |
1996年 | 27篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 17篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 12篇 |
1977年 | 2篇 |
1974年 | 5篇 |
1973年 | 4篇 |
1966年 | 2篇 |
排序方式: 共有891条查询结果,搜索用时 9 毫秒
11.
Weiping Ma Paul W. Brown Sridhar Komarneni 《Journal of the American Ceramic Society》1996,79(6):1707-1710
Tobermorites were synthesized from oxides and from fly ashes under mild hydrothermal conditions. The bulk compositions of the ash-based formulations were adjusted to give the same [Ca]/[Si + Al] ratio as for the oxides. Selective Cs and Sr exchange with these tobermorites was measured. Compared to those prepared from the oxides and from class C fly ash, the tobermorites obtained from class F fly ash exhibited superior Cs and Sr selective properties. This is apparently a result of more extensive Al incorporation with class F fly ash. For example, tobermorite synthesized from class F fly ash exhibited a cesium K d (mL/g) of 3826 while those prepared from oxides and from class C fly ash showed K d values of 1112 and 796, respectively, under the same conditions. These results suggest that fly ash waste materials can be converted into tobermorite, which can serve as a resource in the separation, immobilization, and disposal of radioactive species such as Cs and Sr. 相似文献
12.
A. K. Sahu G. Selvarani S. Pitchumani P. Sridhar A. K. Shukla 《Journal of Applied Electrochemistry》2007,37(8):913-919
Incorporation of silica particles through a sol-gel process into the anode-catalyst layer with a sol-gel modified Nafion-silica
composite membrane renders easy retention of back-diffused water from the cathode to anode through the composite membrane
electrolyte, increases the catalyst-layer wettability and improves the performance of the Polymer Electrolyte Fuel Cell (PEFC)
while operating under relative humidity (RH) values ranging between 18% and 100% with gaseous hydrogen and oxygen reactants
at atmospheric pressure. A peak power density of 300 mW cm−2 is achieved at a load current-density value of 1200 mA cm−2 for the PEFC employing a sol-gel modified Nafion-silica composite membrane and operating at 18% RH. Under similar operating
conditions, the PEFC with a Membrane Electrode Assembly (MEA) comprising Nafion-silica composite membrane with silica in the
anode-catalyst layer delivers a peak power density of 375 mW cm−2. By comparison, the PEFC employing commercial Nafion membrane fails to deliver satisfactory performance at 18% RH due to
the limited availability of water at its anode, acerbated electro-osmotic drag of water from anode to cathode and insufficient
water back diffusion from cathode to anode causing the MEA to dehydrate. 相似文献
13.
S. Sridhar 《JOM Journal of the Minerals, Metals and Materials Society》2002,54(11):46-50
Viscosities of molten metals and slags play vital roles in many high-temperature phenomena that are important for advancing
process control and product quality in molten-metal processing and casting. Because measuring viscosities of high-temperature
melts is expensive, the need exists for reliable viscosity estimation methods based on the temperature and composition of
the melt. This paper reviews some available models for alloys and slags, and examples are shown for melts of interest to both
ferrous and non-ferrous processing 相似文献
14.
Hydroxyapatite (HAP) coatings were developed on type 316L stainless steel (SS) by electrophoretic deposition at various deposition potentials from 30 to 90 V using the stoichiometric HAP (Ca/P ratio 1.67) powder in a suspension of isopropyl alcohol. The optimum coating parameters were established at 60 V and 3 min, after vacuum sintering at 800 °C. The phase purity of the coated surface was confirmed by XRD and secondary ion mass spectrometry confirmed the presence of both Ca and P on the coated layers. The electrochemical corrosion parameters Ecorr (open circuit potential) and pitting potentials, evaluated in Hank’s solution shifted towards noble direction for the HAP coated specimens in comparison with uncoated type 316L SS. Electrochemical impedance spectroscopic investigations revealed higher polarisation resistance and lower capacitance values after immersing the coated specimens in Hanks solution for 200 h. This indicates the stable nature of the coatings formed. 相似文献
15.
Coupled multielectrode array sensors made of carbon steel and stainless steels were evaluated and compared with electrochemical noise (EN) sensors. Good correlations between sensor signals and solution corrosivity were observed for all multielectrode array sensors. Some correlation between the average pit index and solution corrosivity was observed for the carbon steel EN sensors, but not for the stainless steel EN sensors. The time-average noise resistances from the stainless steel EN sensors correlate well with solution corrosivity. There were, however, large random fluctuations and drifting for all EN signals, which make the EN sensors unreliable as real-time monitors. 相似文献
16.
Karen Twietmeyer Sridhar Sadasivan 《Journal of the Society for Information Display》2016,24(5):312-322
Quantum dots (QDs) are increasingly the technology of choice for wide color gamut displays. Two popular options to incorporate QDs into displays include on‐edge and on‐surface solutions. The opto‐mechanical design for an on‐edge QD solution including a LED light bar (“on‐edge QD light bar”) is more complex than the design for a standard white phosphor LED light bar. In this paper, we identify and investigate a range of design parameters for an on‐edge QD light bar, and we show that these parameters have significant influence on system efficiency and color uniformity. The effects of varying these parameters are explored through the use of a custom adjustable testbed and optical raytracing methods. Our testbed data demonstrate the inherent trade‐offs between efficiency and color uniformity and provide guidance for the design of high‐performing displays. The optical raytracing data demonstrate a good predictive capability and support the use of optical modeling methods for a detailed exploration of a wider range of design parameters. 相似文献
17.
Abstract. In this paper two problems on the class of k -trees, a subclass of the class of chordal graphs, are considered: the fast reordering problem and the isomorphism problem. An O(log
2
n) time parallel algorithm for the fast reordering problem is described that uses O(nk(n-k)/\kern -1ptlog n) processors on a CRCW PRAM proving membership in the class NC for fixed k . An O(nk(k+1)!) time sequential algorithm for the isomorphism problem is obtained representing an improvement over the O(n
2
k(k+1)!) algorithm of Sekharan (the second author) [10]. A parallel version of this sequential algorithm is presented that runs in
O(log
2
n) time using O((nk((k+1)!+n-k))/log n) processors improving on a parallel algorithm of Sekharan for the isomorphism problem [10]. Both the sequential and parallel
algorithms use a concept introduced in this paper called the kernel of a k -tree. 相似文献
18.
This article analyzes the transmission line characteristics of plasmonic hybrid metal insulator metal (HMIM) waveguide, circular ring resonator (CRR) based dual-band band-pass filters with two transmission poles in both pass-bands in the optical regime using coupled line feed. The transmission line characteristics of an HMIM waveguide, such as characteristic impedance (ZPV), effective refractive index (neff) and propagation length (Lspp), have been obtained by using full wave simulation. Using basic HMIM slot waveguide, a CRR with periodic loading of double- and triple-ring CRR is numerically analyzed. Two input ports have been used for excitation, which are located at the separation of 180° positions along the CRR, and are coupled with the ring by parallel coupled lines, producing the dual pass-bands with the synchronous excitation of two transmission poles. The proposed double-ring dual-band band-pass filter (DR-DB-BPF) offers 35 dB extinction ratio (ER), 299.69 nm free spectral range (FSR) and narrow band full width half maximum (FWHM) of 78.057—112.43 nm. The triple-ring DB-BPF (TR-DB-BPF) has 22.5 dB ER, FSR of 292.18 nm and FWHM of 42.751—59.58 nm. The proposed filters are very useful in the development of dual-band filters for electronic photonic integrated circuits (EPICs), as the optical signals are filtered at two wavelengths simultaneously. 相似文献
19.
Using the method of drilling holes, the residual stress distributions were determined in two titanium alloys, IMI-685 and IMI-318, in the machined, polished, shot-peened and cyclically stressed (MPSC) as well as the heat-treated and quenched (HTQ) conditions. In IMI-318, the effect of shot-peening pressure on the residual stress distribution was also studied. Tensile cyclic stressing relaxed the shot-peen induced residual stresses in the longitudinal direction and the extent of relaxation depended on the degree of cyclic softening present in the material. In both alloys, in the post- heat-treated and quenched condition, the residual stresses were tensile in nature. In IMI-318, a decrease in the shot-peening pressure led to residual stresses of lower magnitudes. The peak residual stress was present closer to the surface when the shot-peening pressure was increased. 相似文献
20.