全文获取类型
收费全文 | 1252篇 |
免费 | 89篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 233篇 |
金属工艺 | 55篇 |
机械仪表 | 97篇 |
建筑科学 | 18篇 |
能源动力 | 77篇 |
轻工业 | 117篇 |
水利工程 | 4篇 |
无线电 | 237篇 |
一般工业技术 | 271篇 |
冶金工业 | 61篇 |
原子能技术 | 32篇 |
自动化技术 | 132篇 |
出版年
2024年 | 1篇 |
2023年 | 25篇 |
2022年 | 26篇 |
2021年 | 55篇 |
2020年 | 34篇 |
2019年 | 32篇 |
2018年 | 48篇 |
2017年 | 55篇 |
2016年 | 56篇 |
2015年 | 46篇 |
2014年 | 71篇 |
2013年 | 100篇 |
2012年 | 96篇 |
2011年 | 98篇 |
2010年 | 69篇 |
2009年 | 69篇 |
2008年 | 75篇 |
2007年 | 37篇 |
2006年 | 45篇 |
2005年 | 36篇 |
2004年 | 52篇 |
2003年 | 34篇 |
2002年 | 26篇 |
2001年 | 21篇 |
2000年 | 26篇 |
1999年 | 16篇 |
1998年 | 28篇 |
1997年 | 22篇 |
1996年 | 11篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1346条查询结果,搜索用时 15 毫秒
991.
Hocheon Yoo Sungmin On Seon Baek Lee Kilwon Cho Jae‐Joon Kim 《Advanced materials (Deerfield Beach, Fla.)》2019,31(29)
Multivalued logic (MVL) computing could provide bit density beyond that of Boolean logic. Unlike conventional transistors, heterojunction transistors (H‐TRs) exhibit negative transconductance (NTC) regions. Using the NTC characteristics of H‐TRs, ternary inverters have recently been demonstrated. However, they have shown incomplete inverter characteristics; the output voltage (VOUT) does not fully swing from VDD to GND. A new H‐TR device structure that consists of a dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT) layer stacked on a PTCDI‐C13 layer is presented. Due to the continuous DNTT layer from source to drain, the proposed device exhibits novel switching behavior: p‐type off/p‐type subthreshold region /NTC/ p‐type on. As a result, it has a very high on/off current ratio (≈105) and exhibits NTC behavior. It is also demonstrated that an array of 36 of these H‐TRs have 100% yield, a uniform on/off current ratio, and uniform NTC characteristics. Furthermore, the proposed ternary inverter exhibits full VDD‐to‐GND swing of VOUT with three distinct logic states. The proposed transistors and inverters exhibit hysteresis‐free operation due to the use of a hydrophobic gate dielectric and encapsulating layers. Based on this, the transient operation of a ternary inverter circuit is demonstrated for the first time. 相似文献
992.
Seung Jung Yu Kwanyong Pak Moo Jin Kwak Munkyu Joo Bong Jun Kim Myung Seok Oh Jieung Baek Hongkeun Park Goro Choi Do Heung Kim Junhwan Choi Yunho Choi Jihye Shin Heeyeon Moon Eunjung Lee Sung Gap Im 《Advanced Engineering Materials》2018,20(3)
993.
Reduction of DNA Folding by Ionic Liquids and Its Effects on the Analysis of DNA–Protein Interaction Using Solid‐State Nanopore 下载免费PDF全文
Ki‐Baek Jeong Ke Luo Min‐Cheol Lim Jong‐Yoon Jung Jae‐Seok Yu Ki‐Bum Kim Young‐Rok Kim 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(31)
DNA folding is not desirable for solid‐state nanopore techniques when analyzing the interaction of a biomolecule with its specific binding sites on DNA since the signal derived from the binding site could be buried by a large signal from the folding of DNA nearby. To resolve the problems associated with DNA folding, ionic liquids (ILs), which are known to interact with DNA through charge–charge and hydrophobic interactions are employed. 1‐n‐butyl‐3‐methylimidazolium chloride (C4mim) is found to be the most effective in lowering the incident of DNA folding during its translocation through solid‐state nanopores (4–5 nm diameter). The rate of folding signals from the translocation of DNA–C4mim is decreased by half in comparison to that from the control bare DNA. The conformational changes of DNA upon complexation with C4mim are further examined using atomic force microscopy, showing that the entanglement of DNA which is common in bare DNA is not observed when treated with C4mim. The stretching effect of C4mim on DNA strands improves the detection accuracy of nanopore for identifying the location of zinc finger protein bound to its specific binding site in DNA by lowering the incident of DNA folding. 相似文献
994.
Carbon Nanomaterials: Unique Tube–Ring Interactions: Complexation of Single‐Walled Carbon Nanotubes with Cycloparaphenyleneacetylenes (Small 26/2018) 下载免费PDF全文
995.
K.-K. Koo H.-R. Lee S. Jeong Y.-S. Oh D.-R. Park Y.-S. Baek 《International Journal of Thermophysics》1999,20(2):589-600
The optimum mole ratio of lithium salts in the H2O + LiBr + LiNO3 + LiI + LiCl system was experimentally determined to be LiBr : LiNO3 : LiI : LiCl = 5 : 1 : 1 : 2. The solubilities were measured at temperatures from 252.02 to 336.75 K. Regression equations on the solubility data were obtained with a least-squares method. Average absolute deviations of the calculated values from the experimental data were 0.15% at temperatures <285.18 K and 0.05% at temperatures 285.18 K. The vapor pressures were measured at concentrations ranging from 50.0 to 70.0 mass% and at temperatures from 330.13 to 434.88 K. The experimental data were correlated with an Antoine-type equation, and the average absolute deviation of the calculated values from the experimental data was 2.25%. The heat capacities were measured at concentrations from 50.0 to 65.0 mass% and temperatures from 298.15 to 328.15 K. The average absolute deviation of the values calculated by the regression equation from the experimental data was 0.24%. 相似文献
996.
Jin-Gyeong Cho Hee-Jung Park Gyu-Won Huh Seung Su Lee Myun-Ho Bang Kyoung-Sook Choi Chang-Hwan Oh Sung-Kwon Ko Soo-Yeul Cho Kap-Yong Chai Jin-Ho Kim Nam-In Baek 《Food science and biotechnology》2014,23(6):1815-1820
The flavonoids, wighteone (1), naringenin (2), genistein (3), isoliquiritigenin (4), daidzein (5), daidzin (6), genistein-8-C-β-d-apiofuranosyl-(1→6)-O-β-d-glucopyranoside (7), ambocin (8), and genistin (9) were isolated from roots of Pueraria mirifica. Chemical structures of the compounds were determined based on spectroscopic data analysis. Flavonoids 1, 2, 4, 7, and 8 were isolated for the first time. The contents of 6 flavonoids in P. mirifica roots was determined to be 2.5±0.01 (1), 14.8±0.09 (3), 18.6±0.18 (5), 17.3±0.11 (6), 10.4±0.05 (7), and 6.0±0.02 (9) mg/kg, respectively, using HPLC. 相似文献
997.
Vertically grown Si nanowires were prepared as a nanotemplate for conducting polymers. Electrochromic (EC) PEDOT (poly(3,4-ethylenedioxythiophene)) layer was successfully grown on Si nanowires by electrochemical polymerization method to form PEDOT nanowires having average wall thickness of approximately 60nm. As-prepared conductive nanowire electrode was applied to a low voltage working EC device by fabricating an all solid state EC device. The EC properties of the device were enhanced in the nanowire structure, showing reversible fast optical transition by applying +/-2V. The response time (t(R)) of the EC device from the PEDOT grown on Si nanowires was approximately 0.7s, which was much faster than that from PEDOT film coated on ITO glass electrochemically (t(R)=1.9s). 相似文献
998.
Seung-Cheol?Baek Soon-Bum?Kwon Heuy-Dong?KimEmail author 《Journal of Mechanical Science and Technology》2004,18(3):407-418
Prandtl-Meyer expansion flow with homogeneous condensation is investigated experimentally and by numerical computations. The
steady and unsteady periodic behaviors of the diabatic shock wave due to the latent heat released by condensation are considered
with a view of technical application to the condensing flow through steam turbine blade passages. A passive control method
using a porous wall and cavity underneath is applied to control the diabatic shock wave. Two-dimensional, compressible Navier-Stokes
with the nucleation rate equation are numerically solved using a third-order TVD (Total Variation Diminishing) finite difference
scheme. The computational results reproduce the measured static pressure distributions in passive and no passive Prandtl-Meyer
expansion flows with condensation. From both the experimental and computational results, it is found that the magnitude of
steady diabatic shock wave can be considerably reduced by the present passive control method. For no passive control, it is
found that the diabatic shock wave due to the heat released by condensation oscillates periodically with a frequency of 2.40
kHz. This unsteady periodic motion of the diabatic shock wave can be completely suppressed using the present passive control
method. 相似文献
999.
Mechanical characterization of micro/nanoscale structures for MEMS/NEMS applications using nanoindentation techniques 总被引:6,自引:0,他引:6
Mechanical properties of micro/nanoscale structures are needed to design reliable micro/nanoelectromechanical systems (MEMS/NEMS). Micro/nanomechanical characterization of bulk materials of undoped single-crystal silicon and thin films of undoped polysilicon, SiO(2), SiC, Ni-P, and Au have been carried out. Hardness, elastic modulus and scratch resistance of these materials were measured by nanoindentation and microscratching using a nanoindenter. Fracture toughness was measured by indentation using a Vickers indenter. Bending tests were performed on the nanoscale silicon beams, microscale Ni-P and Au beams using a depth-sensing nanoindenter. It is found that the SiC film exhibits higher hardness, elastic modulus and scratch resistance as compared to other materials. In the bending tests, the nanoscale Si beams failed in a brittle manner with a flat fracture surface. The notched Ni-P beam showed linear deformation behavior followed by abrupt failure. The Au beam showed elastic-plastic deformation behavior. FEM simulation can well predict the stress distribution in the beams studied. The nanoindentation, scratch and bending tests used in this study can be satisfactorily used to evaluate the mechanical properties of micro/nanoscale structures for use in MEMS/NEMS. 相似文献
1000.
Young?Nam?Kim Jae?Jung?Hwang Kyung?Yun?Baek Cheon?Seok?Cha In?Young?YangEmail author 《Journal of Mechanical Science and Technology》2003,17(1):48-56
This paper investigates the collapse characteristics of CF/Epoxy composite tubes subjected to axial loads as changing interlaminar
number and outer ply orientation angle. The tubes are aften used for automobiles, aerospace vehicles, trains, ships, and elevators.
We have performed static and dynamic impact collapse tests by a way of building impact test machine with vertical air-compression.
It is fanad that CF/Epoxy tube of the 6 interlaminar number (C-type) with 90° outer orientation angle and trigger absorbed
more energy than the other tubes (A, B and D types). Also collapse mode depended upon outer orientation angle of CF/Epoxy
tubes and loading type as well ; typical collapse modes of CF/Epoxy tubes are wedged, splayed and fragmentcl. 相似文献