全文获取类型
收费全文 | 1272篇 |
免费 | 62篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 75篇 |
综合类 | 2篇 |
化学工业 | 364篇 |
金属工艺 | 30篇 |
机械仪表 | 41篇 |
建筑科学 | 32篇 |
能源动力 | 45篇 |
轻工业 | 99篇 |
水利工程 | 2篇 |
无线电 | 75篇 |
一般工业技术 | 271篇 |
冶金工业 | 101篇 |
原子能技术 | 91篇 |
自动化技术 | 109篇 |
出版年
2023年 | 7篇 |
2022年 | 3篇 |
2021年 | 35篇 |
2020年 | 21篇 |
2019年 | 30篇 |
2018年 | 24篇 |
2017年 | 35篇 |
2016年 | 38篇 |
2015年 | 38篇 |
2014年 | 34篇 |
2013年 | 83篇 |
2012年 | 54篇 |
2011年 | 84篇 |
2010年 | 65篇 |
2009年 | 61篇 |
2008年 | 76篇 |
2007年 | 70篇 |
2006年 | 50篇 |
2005年 | 42篇 |
2004年 | 49篇 |
2003年 | 35篇 |
2002年 | 42篇 |
2001年 | 29篇 |
2000年 | 27篇 |
1999年 | 24篇 |
1998年 | 50篇 |
1997年 | 31篇 |
1996年 | 22篇 |
1995年 | 29篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 3篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有1337条查询结果,搜索用时 15 毫秒
991.
K Wakabayashi K Nakamura M Masaki W Yamamoto K Denda Y Nakamura H Yanagawa 《Canadian Metallurgical Quarterly》1995,50(4):839-848
To obtain basic data concerning the availability of medical care for intractable diseases in a large city and its environs, we analyzed the data of Saitama Prefecture. These data were selected from a nationwide survey conducted by the Epidemiology of Intractable Diseases Research Committee of the Ministry of Health and Welfare in Japan. The characteristics of medical institutions visited by patients with 26 intractable diseases were analyzed. The patients were receiving financial aid for treatment. The subjects were 4234 patients in 1984 and 6804 patients in 1988. In addition, we compared the data of 1984 with those of 1988. The results are as follows: 1) In both years, the characteristics of medical institutions which were visited varied in terms of the individual disease. The proportion of patients who visited medical institutions in the same medical service area and in the same prefecture were both very low. The percentage of patients who visited medical institutions in Tokyo was more than 30% of the total, and was more than 50% for the disease with the highest proportion of patients. The dependency on Tokyo for medical institutions was inversely proportional to the distance from Tokyo. Most patients were highly dependent on a large hospital, but the proportion of patients with SMON and ulcerative colitis who visited a large hospital was markedly lower than that for other diseases. 2) A comparison of the data of 1984 with those of 1988 showed that in most of medical service areas, the proportion of patients who visited medical institutions in the same medical service area and in Saitama Prefecture increased, but in Tokyo Prefecture the proportion decreased. We continuously observed a high dependency on a university hospital located about 60km distance from downtown Tokyo, but the dependency slightly decreased in 1988. When a new branch of a university hospital opened, many intractable disease patients then depended on that branch. These results suggest that the self-sufficiency levels of medical services for intractable diseases gradually rose in Saitama Prefecture. The illness behavior of intractable disease patients in Saitama Prefecture did not show any remarkable changes, therefore those results in Saitama Prefecture might indicate a universal characteristic of medical institutions visited by intractable disease patients who live in the envirous of a large city (Tokyo). 相似文献
992.
993.
Hiroshi?NishiharaEmail author Masaki?Murata 《Journal of Inorganic and Organometallic Polymers and Materials》2005,15(1):147-156
We describe here our recent research on -conjutgated organometallic polymers containing ferrocenyl groups. Internuclear electronic interactions through the -conjugated spacer display unique redox and optical properties. The dependence of the redox properties on the number of ferrocene moieties in oligo(1,1-ferrocenylene)s were analyzed by the neighboring-site interaction model. The electronic structure in the mixed-valence states of biferrocene and terferrocene were estimated using the infrared (IR) spectra. Intervalence-transfer (IT) bands in the mixed-valence states of oligo(1,1-ferrocenylene)s were rationalized by taking into account the change in neighboring-site interaction by photo-electron transfer. Near-IR photoconductivity was found for the charge transfer complex of oligo- and poly-(1,1-ferrocenylene)s with tetracycanoethylene (TCNE). Redox and optical properties of azo-bridged ferrocene oligomers and a polymer was also analyazed based on the neighboring-site interaction model. Metallacyclization reaction of para-bis(ferrocenylethynyl)benzene with CpCo(PPh3)2 affforded a ferrocene-containing cyclobutadienecobalt polymer, of which redox property indicates strong intra-unit and weak inter-unit interactions. 相似文献
994.
Ozone decomposition of 2-methylisoborneol (MIB) in adsorption phase on high silica zeolites with preventing bromate formation 总被引:5,自引:0,他引:5
This work elucidates the applicability of our newly developed adsorptive ozonation process for the decomposition of 2-methylisoborneol (MIB), a typical taste and odor chemical, without the formation of possibly carcinogenic bromate ions. First, zeolite adsorbents were screened for their ability to adsorb MIB with a batch-type adsorption experimental apparatus and a flow-type decomposition experimental apparatus included an adsorbent-packed column. The USY zeolite with the highest silica to alumina ratio (SiO(2)/Al(2)O(3) molar ratio=70) showed the best performance as an adsorbent. Using this adsorbent, an ozonation experiment on an MIB solution including bromide ions was performed under various retention times using the flow-type apparatus. As a result, sufficient decomposition of MIB was achieved with preventing bromate formation. 相似文献
995.
Mitsunori?TakanoEmail author Junichi?Higo Hironori?K.?Nakamura Masaki?Sasai 《Natural computing》2004,3(4):377-393
What granularity is needed to carry out computer simulations of biomolecular reactions/motions? This is one of the central issues of the in silico biomolecular computing. In this paper, we addressed this issue by studying model granularity dependence of the native structure dynamics of protein molecules. We conducted molecular dynamics simulations employing three different protein models: the model with full atomic details and two coarse-grained models in which only Cα atoms interacting with each other through simple potentials are considered. In addition to the observed agreement among the three models in terms of isotropic thermal fluctuation, principal component analysis showed that the coarse-grained models can also reproduce the anisotropy (or directionality) of the fluctuation, particularly of collective modes having relevance to molecular function. This indicates that the dependence of the essential dynamics of a protein molecule on the model granularity is weak, although it was also shown that incorporation of the Lennard–Jones-type potential into the harmonic-potential-based coarse-grained model improves the reproducibility to some degree, and that a plastic nature of structural dynamics observed in the full atomic model transforms into an elastic one in the coarse-grained models. The coarse-grained model can be applied to a molecular motor system, which may lead to a new view of biomolecular computing in the context of biological physics. 相似文献
996.
Track maintenance train operators’ attitudes to job,organisation and management,and their correlation with accident/incident rate 总被引:1,自引:1,他引:0
Kenji?ItohEmail author Henning?Boje?Andersen Masaki?Seki 《Cognition, Technology & Work》2004,6(2):63-78
The present paper reports the results of a questionnaire-based survey of night train operators attitudes toward management, operating procedures, and other organisational issues that potentially impact on safety. Responses were collected from all of the operators of track maintenance trains servicing the Japanese high-speed railway (Shinkansen). Two versions of the questionnaire, the TMAQ (Train Management Attitudes Questionnaire), were developed based on Helmreichs FMAQ (Flight MAQ) and its derivative, the SMAQ (Ship MAQ). The TMAQ and its progenitor seek to elicit respondents views of, and attitudes to, a range of safety related factors including morale, motivation, leadership and human relations in their organisation.To identify dimensions of safety culture as elicited through the TMAQ, a principal component analysis was applied to the questionnaire responses of the original TMAQ. The analysis yielded seven attitude factors, including morale and motivation. Of the seven factors, a close correlation was identified between the factor scores representing operators morale and motivation and the actual accident/incident rates for each of the five branches belonging to a single-track maintenance company. A branch that employed train operators having relatively higher morale and motivation exhibited a lower accident/incident rate. Furthermore, the very same correlation was also found for company based responses collected from all track maintenance companies working for the high-speed railway.In addition to the branch and company based comparisons for track maintenance train operators, we also compared attitude factors between different groups of operators (drivers and supervisors), and between two different periods surveyed in a two year interval. Finally, we examined differences in terms of attitude factors between track maintenance operators and seafarers surveyed by applying slightly different variants of the same generic form of questionnaire (Helmreichs SMAQ). Based on these survey results, we discuss potential risk factors for accidents of track maintenance trains and some implications for improving railway safety. 相似文献
997.
Yuliarto B Zhou H Yamada T Honma I Katsumura Y Ichihara M 《Analytical chemistry》2004,76(22):6719-6726
Self-ordered and structure-controlled transparent films of tin-modified mesoporous silica (Sn/Si ratio of 0.5-3%) were first prepared using a molecule surfactant template method employing spin coating. A surface photovoltage (SPV) NO(2) gas sensor was then fabricated using these self-ordered tin-modified mesoporous silica thin films based on a metal-insulator-semiconductor structure. Highly sensitive tin-modified mesoporous silica was obtained that could detect NO(2) gas concentrations of as low as 300 ppb at room temperature. The detection mechanism for NO(2) is believed to involve both the surface area, which contributes to the change in dielectric constant, and the amount of tin incorporated, which contributes to the change in charge. It was found that, in this SPV sensor, the optimal Sn/Si ratio of 0.5% delivered record-high sensing performance. 相似文献
998.
The carbonation technique was applied to accelerate the hydration of low heat portland cement (LHC). Before carbonation, the demoulded pastes were precured in water for 0, 2, 7, and 21 d, respectively. The results show that procuring time in water strongly influences the carbonation process. The phenolphthalein test indicates that the paste precured in water for a shorter time is more quickly carbonated than that for a longer time. The content of calcium hydroxide increases with increasing the procuring time in water, whereas, the amount of absorbed carbon dioxide changes contrarily. Scanning electron microscope (SEM) observation shows that portlandite always fills up big air bubbles in the paste during precuring in water, and the mercury intrusion porosimetry (MIP) results show that there are less large capillary pores in the paste precured in water for a longer time. It is found that the paste without precuring in water has more carbon dioxide absorption during curing in carbon dioxide atmosphere, and its total pore volume decreases remarkably with an increase in the carbonation time than that precured in water. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface area analyses indicate that the carbonate products are vaterite and calcite; CxSHy,, formed from carbonation has low BET surface area in comparison with that of C-S-H formed from curing in water. 相似文献
999.
Kato T. Ninomiya Y. Masaki I. 《Intelligent Transportation Systems, IEEE Transactions on》2002,3(4):252-260
Preceding vehicle recognition is an important enabling technology for developing a driver assistance system and an autonomous vehicle system. However, this is difficult for computer vision to achieve because of the variety of shapes and colors in which vehicles are made. In this paper, we propose a novel vision-based preceding vehicle recognition method, which has the capability of recognizing a wide selection of vehicles. In the proposed method, classifiers learned from "vehicle" training samples and "nonvehicle" training samples are used to enable recognition. We also propose a novel classification method, the "multiclustered modified quadratic discriminant function" (MC-MQDF). The MC-MQDF is capable of estimating the complex distribution due to the variety of different possible appearances for preceding vehicles. In order to confirm the feasibility of recognizing various vehicles, and to demonstrate the advantage of the MC-MQDF over the MQDF, classification experiments were carried out using the images of various vehicles. In a complex distribution test including a variety of vehicles, the classification rate for the MC-MQDF was approximately 98%, whereas the classification rate for the ordinary MQDF technique was approximately 93%. This supports the superiority of the MC-MQDF technique over the MQDF technique, and demonstrates the feasibility of recognizing a variety of different vehicles. 相似文献
1000.
Atomic structures of an Au (110) 2 x 1 reconstructed surface were analysed quantitatively using an exit wave reconstructed by the three-dimensional Fourier filtering method in high-resolution transmission electron microscopy. To reconstruct the exit wave in a relatively thick crystal, a practical criterion was proposed in the present analysis. In the 'pseudo-exit wave' obtained by the proposed criterion, relaxation of surface atoms was clearly visible in the top three layers. The atoms' displacement was measured to be about 5-20 pm. For quantitative analysis of the atom column positions, image contrast calculations were performed using a structural model of the Au (110) reconstructed surface. Calculations confirmed that the reconstructed pseudo-exit wave could represent the atom column positions directly with an accuracy of several pm, even for a relaxed surface, provided the sample thickness was <7 nm. 相似文献