全文获取类型
收费全文 | 661篇 |
免费 | 20篇 |
专业分类
电工技术 | 20篇 |
综合类 | 1篇 |
化学工业 | 153篇 |
金属工艺 | 28篇 |
机械仪表 | 9篇 |
建筑科学 | 37篇 |
能源动力 | 19篇 |
轻工业 | 95篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 54篇 |
一般工业技术 | 78篇 |
冶金工业 | 117篇 |
原子能技术 | 32篇 |
自动化技术 | 36篇 |
出版年
2022年 | 12篇 |
2021年 | 25篇 |
2020年 | 11篇 |
2019年 | 6篇 |
2018年 | 15篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 20篇 |
2014年 | 15篇 |
2013年 | 36篇 |
2012年 | 26篇 |
2011年 | 52篇 |
2010年 | 25篇 |
2009年 | 32篇 |
2008年 | 37篇 |
2007年 | 24篇 |
2006年 | 24篇 |
2005年 | 27篇 |
2004年 | 27篇 |
2003年 | 20篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 34篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1977年 | 5篇 |
1976年 | 8篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 4篇 |
1970年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有681条查询结果,搜索用时 0 毫秒
51.
In single-objective optimization problems, with only one optimal design objective, the absolute optimal solution to maximize/minimize the objective function can be determined. However, in most real design problems, the optimization problems are multi-objective, where two or more independent design objectives must be optimized simultaneously, and no single absolute optimal solution necessarily exists. In these cases, it is helpful for designers to recognize the range of alternative solutions that exist in Pareto-optimal sets and choose an acceptable solution from among them. In this paper, the authors carried out multi-objective optimization using Multiple Objective Genetic Algorithms through a real case study involved in indoor environmental design – the design of outer windows. Then the authors analyzed structure of Pareto-optimal solution sets. Here we present the analysis process as well as the case study details, and show how the method proposed here is effective at finding an acceptable solution for multi-objective optimization problems. 相似文献
52.
In residential building design, areaways can act as an open subsurface space to help improve the living environment in adjacent basements for residential purposes, mainly by wind-induced natural ventilation. The accurate prediction of effective air change rate is quite important; nevertheless so far little is known about this kind of ventilation issue. In order to acquire more knowledge in this field and make accurate ventilation predictions, direct measurement of ventilation rate was performed in this study using small-scale wind tunnel models. In the experiment, considering ventilation induced only by the exterior wind, we applied the constant tracer gas flow technique to measure the time-averaged ventilation rate for nine wind directions for each case. Furthermore, the relationships between the ventilation rate and a variety of parameters including wind direction, opening type, plan area of the areaway space and building coverage ratio, etc. were investigated and analyzed in detail. The findings of the present study can provide fundamental data for the design of areaway space in the urban residential buildings. 相似文献
53.
Douglas A. Kuntz Dr. Shinichi Nakayama Kayla Shea Hitoshi Hori Prof. Dr. Yoshihiro Uto Dr. Hideko Nagasawa Prof. Dr. David. R. Rose Prof. Dr. 《Chembiochem : a European journal of chemical biology》2010,11(5):673-680
Golgi α‐mannosidase II (GMII) is a key enzyme in the N‐glycosylation pathway and is a potential target for cancer chemotherapy. The natural product swainsonine is a potent inhibitor of GMII. In this paper we characterize the binding of 5α‐substituted swainsonine analogues to the soluble catalytic domain of Drosophila GMII by X‐ray crystallography. These inhibitors enjoy an advantage over previously reported GMII inhibitors in that they did not significantly decrease the inhibitory potential of the swainsonine head‐group. The phenyl groups of these analogues occupy a portion of the binding site not previously seen to be populated with either substrate analogues or other inhibitors and they form novel hydrophobic interactions. They displace a well‐organized water cluster, but the presence of a C(10) carbonyl allows the reestablishment of important hydrogen bonds. Already approximately tenfold more active against the Golgi enzyme than the lysosomal enzyme, these inhibitors offer the potential of being extended into the N‐acetylglucosamine binding site of GMII for the creation of even more potent and selective GMII inhibitors. 相似文献
54.
Bioaccumulation, temporal trend, and geographical distribution of synthetic musks in the marine environment 总被引:3,自引:0,他引:3
Nakata H Sasaki H Takemura A Yoshioka M Tanabe S Kannan K 《Environmental science & technology》2007,41(7):2216-2222
Bioaccumulation of synthetic musks in a marine food chain was investigated by analyzing marine organisms at various trophic levels, including lugworm, clam, crustacean, fish, marine mammal, and bird samples collected from tidal flat and shallow water areas of the Ariake Sea, Japan. Two of the polycyclic musks, HHCB and AHTN, were the dominant compounds found in most of the samples analyzed, whereas nitro musks were not detected in any of the organisms, suggesting greater usage of polycyclic musks relative to the nitro musks in Japan. The highest concentrations of HHCB were detected in clams (258-2730 ng/g lipid wt.), whereas HHCB concentrations in mallard and black-headed gull were low, and comparable with concentrations in fish and crab. These results are in contrast to the bioaccumulation pattern of polychlorinated biphenyls; for which a positive correlation between the concentration and the trophic status of organisms was found. Such a difference in the bioaccumulation is probably due to the metabolism and elimination of HHCB in higher trophic organisms. Temporal trends in concentrations of synthetic musks were examined by analyzing tissues of marine mammals from Japanese coastal waters collected during 1977-2005. HHCB concentrations in marine mammals have shown significant increase since the early 1990s, suggesting a continuous input of this compound into the marine environment. Comparison of the time trend for HHCB with those for PCBs and PBDEs suggested that the rates of increase in HHCB concentrations were higher than the other classes of pollutants. To examine the geographical distribution of HHCB, we have analyzed tissues of fish, marine mammals, and birds collected from several locations. Synthetic musks were not detected in a sperm whale (pelagic species) from Japanese coastal water and in eggs of south polar skua from Antarctica. While the number of samples analyzed is limited, these results imply a lack of long-range transportation potential of synthetic musks in the environment. 相似文献
55.
YoonKeun Chae JinWon Park Shinsuke Mori Masaaki Suzuki 《Journal of Industrial and Engineering Chemistry》2012,18(4):1237-1241
The partial reduction of TiO2 was attempted by heat treatment and plasma-heat treatment and it was carried out to investigate the photocatalytic characteristics of partially reduced TiO2 (TiO2?x) in the visible-light region. As a result, the plasma-heat treatment shows significantly stronger than the heat treatment for the visible-light photocatalytic activity of TiO2. The red-shifted absorption bands in the visible-light region of TiO2?x by plasma-heat treatment gave broader than one by heat treatment. The TiO2?x by heat treatment and plasma-heat treatment was changed white to beige color, and white to navy, respectively. 相似文献
56.
Shinsuke Takase Kazuo Kashiyama Seizo Tanaka Tayfun E. Tezduyar 《Computational Mechanics》2011,48(3):293-306
We show that combination of the Deforming-Spatial-Domain/Stabilized Space–Time and the Streamline-Upwind/Petrov–Galerkin formulations
can be used quite effectively for computation of shallow-water flows with moving shorelines. The combined formulation is supplemented
with a stabilization parameter that was originally introduced for compressible flows, a compressible-flow shock-capturing
parameter adapted for shallow-water flows, and remeshing based on using a background mesh. We present a number of test computations
and provide comparisons to theoretical results, experimental data and results computed with nonmoving meshes. 相似文献
57.
Takashi Wakuda Kazuo Azuma Hiroyuki Saimoto Shinsuke Ifuku Minoru Morimoto Ichiro Arifuku Masahito Asaka Takeshi Tsuka Tomohiro Imagawa Yoshiharu Okamoto Tomohiro Osaki Saburo Minami 《Journal of Functional Foods》2013,5(1):516-523
The effects of pear vinegar (PV), which was specially brewed for enhanced galacturonic acid content, on the DSS-induced ulcerative colitis (UC) mouse model were evaluated. PV improved clinical symptoms, colon inflammation, and histological tissue injury in the DSS-induced acute UC mouse model. Moreover, PV suppressed inflammation due to acute UC by suppressing the myeloperoxidase (MPO)-mediated activation of inflammatory cells such as leukocytes and decreasing the serum concentration of IL-6. Our results demonstrated the protective action of PV in the DSS-induced acute UC mouse model. On the other hand, commercial apple vinegar did not show a protective effect in the DSS-induced acute UC mouse model. Our findings indicate that PV may act as a new functional food for inflammatory bowel disease patients. 相似文献
58.
The integration of three-dimensional spatial distributions into building simulations is of significant interest, and computational
fluid dynamics (CFD) analysis is widely employed in building design processes. For example, based on the experience of architects
and engineers, CFD analyses are often conducted under steady boundary conditions to determine the degree of attainment of
indoor environments. However, CFD analyses have large calculation costs and cannot be often used for simulations with unsteady
boundary conditions such as energy simulations in the building design processes. Thus, we developed a method that calculates
sensitivities from heat sources to an arbitrary point in an indoor environment and integrates them into simulations with unsteady
boundary conditions. In the proposed method, CFD analysis is employed under steady boundary conditions to calculate the response
factors, and the resulting sensitivities are integrated into simulations under unsteady boundary conditions. In the present
study, the proposed method was applied to optimize the variables of an air conditioning control system. With our method, temperature
changes at a sensor over time are calculated from the time series of air supply temperature. In total, 800 calculations were
conducted, and the optimal variables that allow the temperature at the sensor to reach the target value quickly were obtained.
Except for the time required to calculate the response factors, the optimization in the present study took only a few seconds.
If only CFD analysis was used for the optimization, the calculations would take a year. Thus, calculating the sensitivities
via CFD analysis and utilizing the results in simulations is a useful approach for solving optimization problems. Moreover,
the proposed method is applicable to simulations that require three-dimensional spatial distributions to enhance the accuracy
of the calculation such as energy simulations. 相似文献
59.
K Kajiwara E Sugaya N Yuyama H Nagasawa T Tsuda A Sugaya M Motoki K Shimizu-Nishikawa M Kimura 《Canadian Metallurgical Quarterly》1997,47(1-2):49-58
To determine the molecular mechanism of regulation of pentylenetetrazol (PTZ)-induced calcium entry by the seizure-related gene, PTZ-17, the role of the 3'-untranslated region (3'UTR) and also interaction between 3'UTR and intracellular factors were investigated. PTZ-induced calcium inward current in Xenopus oocytes injected with PTZ-17 RNA varied in magnitude among strains of mice: RNA derived from the DBA/2 mouse, which has a high susceptibility to convulsions, showed the largest current and that from the BALB/c mouse with a low susceptibility to convulsions showed no PTZ response. The sequence of 3'UTR showed alterations among mouse strains: 3'UTR of BALB/c showed a sequence alteration from T to G and that of DBA/2 showed a GTG insertion compared with that of B6. The 3'UTR also regulated the translation of chloramphenicol acetyltransferase (CAT) RNA depending on its sequence. A particular region within the 3'UTR demonstrated interaction with 60- and 47-kDa proteins. Sequence alterations in this region corresponded to disappearance or increase in PTZ-induced calcium entry. These findings suggest that a particular region within 3'UTR of the seizure-related gene, PTZ-17, is involved in PTZ-induced calcium entry via interaction between mRNA and specific RNA-binding proteins. 相似文献
60.
Keisuke Fukushima Hiroshi Fujimoto Shinsuke Nakagawa 《Electrical Engineering in Japan》2008,162(1):66-72
In a short‐span seeking‐mode of hard disk drives, the resonance modes are getting crucial obstruction to meet the demand on high‐speed data access. In this paper, a novel vibration suppression perfect tracking control (PTC) method is proposed based on controllable canonical realization. In the proposed method, it is assumed that the plant is modeled as the rigid and primary resonance mode. By using this model, the feed forward controller is designed with PTC by multirate sampling control in order to suppress the primary vibration. Additionally, the higher‐order resonance vibration is attenuated by using the trajectory MHVT. The proposed method achieved 16% faster seeking than MPVT, a conventional method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 66–72, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20546 相似文献