全文获取类型
收费全文 | 721篇 |
免费 | 19篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 23篇 |
综合类 | 4篇 |
化学工业 | 237篇 |
金属工艺 | 26篇 |
机械仪表 | 5篇 |
建筑科学 | 4篇 |
能源动力 | 58篇 |
轻工业 | 55篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 42篇 |
一般工业技术 | 185篇 |
冶金工业 | 25篇 |
原子能技术 | 16篇 |
自动化技术 | 61篇 |
出版年
2022年 | 5篇 |
2021年 | 18篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 7篇 |
2014年 | 32篇 |
2013年 | 37篇 |
2012年 | 39篇 |
2011年 | 36篇 |
2010年 | 34篇 |
2009年 | 39篇 |
2008年 | 36篇 |
2007年 | 44篇 |
2006年 | 49篇 |
2005年 | 28篇 |
2004年 | 25篇 |
2003年 | 20篇 |
2002年 | 26篇 |
2001年 | 25篇 |
2000年 | 12篇 |
1999年 | 14篇 |
1998年 | 19篇 |
1997年 | 9篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有744条查询结果,搜索用时 187 毫秒
721.
Hydrogen fermentation properties of undiluted cow dung 总被引:2,自引:0,他引:2
Yokoyama H Waki M Ogino A Ohmori H Tanaka Y 《Journal of Bioscience and Bioengineering》2007,104(1):82-85
Anaerobic treatment of undiluted cow dung (15% total solids), so-called dry fermentation, produced hydrogen (743 ml-H(2)/kg-cow dung) at an optimum temperature of 60 degrees C, with butyrate and acetate formation. The hydrogen production was inhibited by the addition of NH(4)(+) in a dose-dependent manner. A bacterium with similarity to Clostridium cellulosi was detected in the fermented dung by a 16S rDNA analysis. 相似文献
722.
Takahiro Mizuta Tomohiro Ikuta Takashi Minemoto Hideyuki Takakura Yoshihiro Hamakawa Takahiro Numai 《Solar Energy Materials & Solar Cells》2006,90(1):46-56
Antireflection (AR) coatings for spherical crystalline silicon solar cells are theoretically optimized from the viewpoint of achieving the largest photon densities in the spherical crystalline silicon solar cells. Because the AR film thickness is optimized with regard to the photon densities in the spherical crystalline silicon solar cells, tolerance in the film thickness can be evaluated. Also, the optimized AR film thicknesses for the spherical crystalline silicon solar cells and planar crystalline silicon solar cells are compared, and analytic expressions for the optimized AR film thicknesses are derived as a function of a quarter-wavelength film thickness. 相似文献
723.
Takashi Minemoto Yasuhiro Hashimoto Wahid Shams-Kolahi Takuya Satoh Takayuki Negami Hideyuki Takakura Yoshihiro Hamakawa 《Solar Energy Materials & Solar Cells》2003,75(1-2):121-126
The effects of conduction band offset of window/Cu(In,Ga)Se2 (CIGS) layers in wide-gap CIGS based solar cells are investigated. In order to control the conduction band offset, a Zn1−xMgxO film was utilized as the window layer. We fabricated CIGS solar cells consisting of an ITO/Zn1−xMgxO/CdS/CIGS/Mo/glass structure with various CIGS band gaps (Eg≈0.97–1.43 eV). The solar cells with CIGS band gaps wider than 1.15 eV showed higher open circuit voltages and fill factors than those of conventional ZnO/CdS/CIGS solar cells. The improvement is attributed to the reduction of the CdS/CIGS interface recombination, and it is also supported by the theoretical analysis using device simulation. 相似文献
724.
Takashi Minemoto Masanori Toda Shingo Nagae Masahiro Gotoh Akihiko Nakajima Kenji Yamamoto Hideyuki Takakura Yoshihiro Hamakawa 《Solar Energy Materials & Solar Cells》2007,91(2-3):120-122
Effects of spectral irradiance distributions on the outdoor performance of amorphous Si//thin-film crystalline Si stacked photovoltaic (PV) modules installed at Shiga-prefecture in Japan have been investigated. Outdoor solar spectrum measurements revealed that more than 95% of annual total spectra were blue-rich compared to AM1.5 standard solar spectrum. The outdoor performance of the modules had a higher spectral dependence than that of polycrystalline Si modules. Also, the peak of the histogram of annual spectral indexes well corresponded to the peak of the outdoor performance. The results indicate that the actual spectral irradiance distribution is important in designing stacked PV modules. 相似文献
725.
Decheng Li Yasuhiro Kato Koichi Kobayakawa Hideyuki Noguchi Yuichi Sato 《Journal of power sources》2006,160(2):1342-1348
LiNi1/3Mn1/3Co1/3O2 prepared by a spray drying method exhibited poor cyclic performance when it was operated at rates of 0.5C and 2C in 3–4.6 V. A metal oxide (ZrO2, TiO2, and Al2O3) coating (3 wt%) could effectively improve its cyclic performance at both 0.5C and 2C. Electrochemical impedance spectroscopy (EIS) studies suggested that both the surface resistance and the charge transfer resistance of the bare LiNi1/3Mn1/3Co1/3O2 significantly increase after 100 cycles, whose origin is mainly related to the change in both the particle surface and electrode morphologies. The presence of a thin metal oxide layer could remarkably suppress the increase in the total resistance (sum of the surface resistance and the charge transfer resistance), which was attributed to the improvement in good cyclic performances. 相似文献
726.
To examine the usefulness of measurement of adenosine triphosphate (ATP)-related compounds for estimation of the quality of canned and/or retorted fishes, we investigated the ATP-related compounds, in sashimi (for raw-eating)-grade and for-cooking-grade chub mackerel Scomber japonicus before and after retort process (121 °C for 30 min) by HPLC method. By the deterioration (storage time) and retort process, inosine monophosphate (IMP), an umami-taste compound, was decreased and inosine (HxR), hypoxantine (Hx) and the K-value, an index of fish freshness defined as the ratio of the sum of HxR and Hx to the sum of ATP-related compounds, were increased. By the retorting, the K-values of sashimi-grade, for-cooking-grade and unacceptable-grade meats were increased from 9.9%, 26.6% and 70% to 36%, 46% and 81%, respectively. These results suggest that the measurement of ATP-related compounds in retorted fish products may estimate the freshness in raw materials, the product quality and/or the good manufacture practices. 相似文献
727.
Hideyuki Kobayashi Akihiko Sugiura 《IEEJ Transactions on Electrical and Electronic Engineering》2012,7(4):383-389
We propose a system to estimate the traffic congestion distance using IEEE 802.15.4, that is extended by multicommunication frequency division multiplexing. Our proposed system is developed at 20% equipped rate, where five lanes are considered. Furthermore, in our proposed system, it is assumed that the equipped rate in all lanes increases. Our proposed method can estimate an error rate lower than 10% approximately at on equipped rate greater than 50%. Additionally, we use 16 terminals in the actual environment. From the actual experiment, we find that our proposed method involving the use of communication pattern 2 is 300% faster than the existing method. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
728.
Hyung-Mok Kim Junya Inoue Hideyuki Horii 《International Journal of Rock Mechanics and Mining Sciences》2004,41(6):959-974
Underground excavation can induce significant deformation of pre-existing joints in rock mass. Due to the sliding and opening of the joints, consequent changes in the flow characteristics of a jointed rock mass would be anticipated. In the present work, a number of numerical techniques are employed and combined in order to evaluate the excavation-induced changes in the flow properties of a jointed rock mass. These are represented by the Micromechanics-Based Continuum (MBC) model analysis (FE excavation analysis in a jointed rock mass), and FracMan/Mafic package (FE flow and transport analysis in the discrete network of joints). A separate computational module connecting these two codes is incorporated to modify initially imposed transmissivities into the excavation-induced ones. The effect of excavation on the flow properties is evaluated by including these excavation-induced transmissivity changes of individual joints in the FE flow analysis. The excavation-induced transmissivities are calculated by the numerical and analytical techniques developed for flow through a single rock joint. The calculation of the excavation-induced transmissivity involves the distributions of shear displacements and normal stresses around the excavation, and implicitly takes into account the effect of surface geometric roughness. A test simulation for a deep underground repository is performed to illustrate the typical results predicted in the proposed approach. 相似文献
729.
Sensitive detection of near-infrared (NIR) spectra of several organic liquids has been carried out by surface plasmon resonance (SPR) NIR spectroscopy. For all the liquids, 50- to 100-fold enhancements of the absorption peaks were obtained in the combination band region 4500-4000 cm(-1) using a gold film with a thickness of 14 nm. The SPR peak shows up as an unnecessary broadband peak or trend in an SPR-NIR spectrum, and it was difficult to separate it from the absorption signals. In order to remove the contribution of SPR from the raw SPR-NIR spectrum, the second-order derivative has been employed. The second derivative of the SPR-NIR spectrum was reasonably comparable to that of the corresponding transmittance spectrum. Two simple algorithms for sample identification from the second-derivative data have been proposed. One is similarity, which directly compares the second-derivative spectrum of an unknown sample with that of a known reference sample. The other is fitness, which is defined as a ratio of the common part of absorption peak wavenumbers of the sample and the reference. Although both methods are unfit for the identification of a minor component in a mixture, a major component can be definitely identified by choosing an informative wavenumber region. It was found that the wavenumber region 4250-4080 cm(-1) is especially useful for the identification of similar molecules such as normal alkanes. 相似文献
730.
We demonstrate the use of self-assembled bionanostructures in polymer light-emitting diodes. Amyloid fibrils formed by protein misfolding were decorated with a soluble luminescent conjugated polymer. This conjugated polymer complex with amyloid fibrils was used as the active layer in a light emitting diode, resulting in a 10-fold increase in external quantum efficiency compared with pristine polymer, because of improved carrier injection. 相似文献