全文获取类型
收费全文 | 1222篇 |
免费 | 101篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 218篇 |
金属工艺 | 55篇 |
机械仪表 | 95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 | 270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 | 11篇 |
2021年 | 55篇 |
2020年 | 34篇 |
2019年 | 31篇 |
2018年 | 48篇 |
2017年 | 55篇 |
2016年 | 55篇 |
2015年 | 45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1328条查询结果,搜索用时 46 毫秒
51.
Sung-Dae Kim Sang-Hwa Baek Tae-Yeob Kang So-Jin Park Chulju Kim Han Seo Ko 《Journal of Mechanical Science and Technology》2012,26(10):3339-3345
Thermal behaviors of combined weapon systems were analyzed by developed computational programs in this study. Also, temperature distributions of the materials of the system were measured according to the experimental conditions. Field tests that reflected the calculated thermal flow characteristics and the measured temperature distributions of the materials were prepared in a large environmental tester for the weapon systems. Boundary conditions of the analysis were the inlet and outlet conditions of the environmental tester and the low temperature limit of ?32°C. The soaking time of the system, including a fuel tank and a battery in the environmental tester, was obtained by the programs developed in this study to carry out the experiment in the predicted conditions. 相似文献
52.
Sung Kun Hyuk Shin Hyun Ju Baek Dabin Ryou Hong Sun 《Journal of Mechanical Science and Technology》2017,31(8):4029-4034
Journal of Mechanical Science and Technology - The major function of smoke control system is to prevent smoke from penetrating to vertical shaft or stairwell by pressurizing vestibule where is... 相似文献
53.
Optoelectronics: High‐Performance Planar Perovskite Optoelectronic Devices: A Morphological and Interfacial Control by Polar Solvent Treatment (Adv. Mater. 23/2015) 下载免费PDF全文
54.
A Surface Tailoring Method of Ultrathin Polymer Gate Dielectrics for Organic Transistors: Improved Device Performance and the Thermal Stability Thereof 下载免费PDF全文
Hyejeong Seong Jieung Baek Kwanyong Pak Sung Gap Im 《Advanced functional materials》2015,25(28):4462-4469
Tailoring the surface of the dielectric layer is of critical importance to form a good interface with the following channel layer for organic thin film transistors (OTFTs). Here, a simple surface treatment method is applied onto an ultrathin (<15 nm) organosilicon‐based dielectric layer via the initiated chemical vapor deposition (iCVD) to make it compatible with organic semiconductors without degrading its insulating property. A molecular‐thin oxide capping layer is formed on a 15 nm thick poly(1,3,5‐trimetyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) by a brief oxygen plasma treatment. The capping layer greatly enhances the thermal stability of the dielectrics, without degrading the original mechanical flexibility and insulating performance of the dielectrics. Moreover, the surface silanol functionalities formed by the plasma treatment can also be utilized for the surface modification with silane compounds. The surface‐modified dielectrics are applied to fabricate low‐voltage operating (<5 V) pentacene‐based OTFTs. The highest field‐effect mobility of the device with the surface‐treated 15 nm thick pV3D3 is 0.59 cm2 V?1 s?1, which is improved up to two times compared to the TFT with the pristine pV3D3. It is believed that the simple surface treatment method can widely extend the applicability of the highly robust, ultrathin, and flexible pV3D3 gate dielectrics to design the surface of the dielectrics to match well various kinds of organic semiconductors. 相似文献
55.
Formation and Accumulation of Intragranular Pores in the Hydrothermally Synthesized Barium Titanate Nanoparticles 下载免费PDF全文
Changyeon Baek Ji Eun Wang San Moon Chang‐Hak Choi Do Kyung Kim 《Journal of the American Ceramic Society》2016,99(11):3802-3808
As highly integrated circuits are demanded for high‐performance electric devices, small sizes of barium titanate (BaTiO3) as a dielectric material are desirable for the application of multilayer ceramic capacitors. Since the small sizes of the particles degrade the dielectric property, especially below a certain critical size, understanding the probable cause is significant for the high‐performance capacitors. Here, we have demonstrated nanosized BaTiO3 with average size below 30 nm and a uniform size distribution. High‐resolution transmission electron microscopy (TEM) shows that the as‐synthesized BaTiO3 contains intragranular pores. We have analyzed the correlation between the intragranular pores inside nanoparticles and their phase ratio of cubic and tetragonal. We have found that the presence of the intragranular pores affects low tetragonality of BaTiO3 particles, and the intragranular pores are generated by the accumulation of hydroxyl groups during hydrothermal reaction. Formation and accumulation of intragranular pores have been investigated by ex‐situ synchrotron X‐ray diffraction and TEM analysis, suggesting the phase evolution model of nanosized BaTiO3. 相似文献
56.
Two donor–acceptor-type alternating copolymers consisting of 2,1,3-benzoselenadiazole and carbazole derivatives with thiophene or selenophene π-bridges were synthesized by Suzuki cross-coupling polymerization, and their optical, electrochemical, and photovoltaic properties were compared. The selenophene π-bridged copolymer (PCz-DSeBSe) exhibited a smaller band-gap (1.82 eV) than the thiophene-bridged polymer (PCz-DTBSe; 1.89 eV). PCz-DSeBSe also showed a deeper highest occupied molecular orbital energy level (−5.36 eV) than PCz-DTBSe (−5.20 eV). Moreover, the PCz-DSeBSe thin film showed higher crystallinity and hole mobility than the PCz-DTBSe thin film. Organic photovoltaic devices were fabricated using the polymers as the donors and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. The device using PCz-DSeBSe showed a higher open circuit voltage (Voc), short circuit current density (Jsc), and power conversion efficiency (PCE) than that using PCz-DTBSe. The fabricated indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/PCz-DSeBSe:PC71BM/LiF/Al device showed the maximum PCE of 2.88% with a Jsc of 7.87 mA/cm2, an Voc of 0.80 V, and a fill factor of 0.50 under AM 1.5G irradiation (100 mW/cm2). 相似文献
57.
Man Young Kim Seung Wook Baek Jae Hyun Park 《Numerical Heat Transfer, Part B: Fundamentals》2013,63(6):617-635
The radiative heat transfer in a complex two-dimensional enclosure with obstacles with participating medium is very important in practical engineering applications. In order to deal with this problem, in this study the finite-volume method (FVM) for radiation has been derived using the unstructured grid system. A general discretization equation was formulated by introducing the directional weight and the step scheme for spatial differencing. For its comparison and validation, two test cases, an equilateral triangular enclosure and a square enclosure with baffle, were chosen. Then, more complex and practical cases, such as a semicircular enclosure with cylinder hole, a square enclosure with finned internal cylinder, and a furnace with embedded cooling pipes, were investigated. All the results obtained by the unstructured FVM agreed very well with the exact solutions as well as the results obtained by the zone method. Furthermore, the wiggling behavior occurring in the blocked-off FVM was not produced by the unstructured FVM. Three types of manipulation of control angle overlap were also examined here. It was found that the solutions depended on the type of manipulation of control angle overlap, especially when the number of control angles was small. Usually, both the pixelation method and exact treatment introduced here yielded better solutions than the bold approximation. 相似文献
58.
Do-Sik Shim Jong-Youn Son Eun-Mi Lee Gyeong-Yun Baek 《International Journal of Material Forming》2017,10(4):581-596
This paper focuses on the corrugated thin-walled sheet metal in the roll bending process. The main defect that appears in corrugated panels subjected to high amounts of bending deformation is a wavy edge. Edge defects are caused by excessive longitudinal stress and strain near the edge of the plate, and local edge buckling may occur when some critical value of the bending radius is exceeded. This paper proposes two different approaches to avoid a wavy edge for a formed panel: excessive stress on the edge region is restrained by controlling the length of the cross-sectional end of the corrugated panel while considering the stress distribution, and the bending radius in each forming step is determined by considering the strain limit at which the initial edge waviness occurs to avoid excessive compression at particular steps. The experimental and numerical results indicated that the two proposed design strategies can minimize wavy edges in the formed shape. 相似文献
59.
A pin power reconstruction method that is readily applicable to multigroup problems with superior accuracy is presented for applications involving rectangular fuel assemblies. It employs a two-dimensional (2D), fourth order Legendre expansion of the source distribution that naturally leads to a group-decoupled, 2D semi-analytic solution of the neutron diffusion equation. The four surface average currents and four corner fluxes are used as the boundary conditions to uniquely specify the homogenous solution. The corner fluxes and source expansion coefficients are iteratively determined using the condition of corner point balance and the orthogonal property of the Lengedre functions. Corner discontinuity is incorporated in the calculation of the corner fluxes which turns out to be very effective in the cases of enrichment zoning. The accuracy of the proposed method is assessed by performing the two-step core calculations for the L336C5, C5G7MOX, and MOX core transient benchmark problems and then by comparing with the direct whole-core transport solutions. The results indicate that the proposed method is as accurate as the fully analytic method and works well irrespective the number of groups. However, it is also noted that somewhat larger errors are inevitable at the peripheral assemblies near the reflector in which the error associated with a prioi generation of the homogenized cross-sections and form functions is not trivial. 相似文献
60.
Seong-Joon Baek Aaron Park Jinyoung Kim Aigou Shen Jiming Hu 《Chemometrics and Intelligent Laboratory Systems》2009,98(1):24-30
In this paper, we consider a new background elimination method for Raman spectra. The proposed method is based on peak detection, smoothing, and interpolation. Since the background is usually slowly varying with respect to wavelength, we could estimate the background by eliminating significant peaks. For this purpose, we seek the peaks by inspecting the smoothed derivative of a given spectrum. After clipping out the corresponding peak regions, we estimate the background by applying a modified linear interpolation. Then the background is eliminated from the measured Raman spectrum by simple subtraction. The experimental results showed that the proposed method gave satisfactory results for real Raman spectra as well as synthetic data. As the proposed method requires no prior knowledge of spectrum, we expect that the method could be applied to other spectral data as well. 相似文献