全文获取类型
收费全文 | 409篇 |
免费 | 9篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 62篇 |
金属工艺 | 19篇 |
机械仪表 | 17篇 |
建筑科学 | 5篇 |
能源动力 | 12篇 |
轻工业 | 30篇 |
无线电 | 57篇 |
一般工业技术 | 60篇 |
冶金工业 | 120篇 |
原子能技术 | 12篇 |
自动化技术 | 15篇 |
出版年
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 3篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 5篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 14篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 23篇 |
2008年 | 16篇 |
2007年 | 23篇 |
2006年 | 13篇 |
2005年 | 16篇 |
2004年 | 7篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 39篇 |
1997年 | 30篇 |
1996年 | 32篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 15篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1959年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有420条查询结果,搜索用时 656 毫秒
21.
A service provisioning system for distributed personalization with private data protection 总被引:1,自引:0,他引:1
Personalized services can provide significant user benefits since they adapt their behavior to better support the user. Personalized services use a variety of data related to the user to decide their behavior. Thus personalized service needs a provisioning system that can collect the data that impacts service behavior and allows selection of the most appropriate service. However, in the coming ubiquitous environment, some data necessary for determining service behavior might be unavailable due to two possible reasons. One is that the data does not exit. The other is that the data exists but cannot be accessed. For example, users do not want to disclose their personal information, and service providers do not also want to expose data related to their knowhow in services. This paper describes a new service provisioning system for distributed personalization with private data protection. Specifically, the system selects applicable services by assessing how well each candidate service behaves when some data is missing. It then executes those selected services while hiding the users’ and providers’ private data in a distributed manner. We first summarize the requirements for a personalized service system, and introduce our fundamental policies for the system. The two main components of our system are then described in detail. One component is a service assessment mechanism that can judge if a service can work without data that can be used for adaptation. The second component is a service execution mechanism that can utilize private data while still ensuring privacy. This component divides service logic and executes divided logic where necessary data is available. The paper finally describes our prototype implementation and its performance evaluation results. 相似文献
22.
Abdul Manaf Hashim Seiya Kasai Kouichi Iizuka Tamotsu Hashizume Hideki Hasegawa 《Microelectronics Journal》2007,38(12):1268-1272
Theoretical analysis of potential distribution in the interdigital-gated high electron mobility transistor (HEMT) plasma wave device was carried out. The dc I–V characteristics of capacitively coupled interdigital structure showed that uniformity of electric field under the interdigital gates was improved compared to the dc-connected interdigital gate structure. Admittance measurements of capacitively coupled interdigital gate structure in the microwave region of 10–40 GHz showed the conductance modulation by drain–source voltage. These results indicate the existence of plasma wave interactions. 相似文献
23.
Takeshi Kasai 《化学工程与技术》1989,12(1):218-225
Most chemical engineers presently accept that the mass transfer rate in desorption from the solid to the gas phase or from the liquid to the gas phase is accelerated with increasing temperature in the liquid or the solid phase, or increasing partial pressure of inert gas in the gas phase, and/or decreasing total system pressure in the gas phase. Nevertheless, many reports about such mass transfer are still based on the former concept, which completely contradicts the actual phenomena mentioned above. Here, we discuss the contradiction and suggest a way of resolving it in terms of diffusion theory. 相似文献
24.
Y Ninomiya T Kishimoto T Yamazawa H Ikeda Y Miyashita H Kasai 《Canadian Metallurgical Quarterly》1997,16(5):929-934
Age is the most important factor for the durability of biological valves. With an original design the Carpentier-Edwards pericardial valve showed improved results at 10 years. The influence of age on valve related complications is studied with a 10 year follow up on 807 valvular replacements. METHODS: Between January 1984 and December 1993, 807 patients underwent valve replacements with a Carpentier-Edwards pericardial bioprosthesis. Patients, 193 were younger than 60 years, 284 between 60 and 70 years and 330 patients were older than 70 years. All patients but seven were followed up for an average of 4.18 years after their operation and total follow up was 3373 patient years. Patients were divided into three groups of age: group I, less than 60 years; group II, 60-70 years; group III, over 70 years. A retrospective comparison was made between age groups. RESULTS: At 11 years, valve related complications included 97 patients with 27 valve related deaths. Rates of valve related death increase with age linearized rate were 0.3, 0.6 and 1.2%, respectively. No difference was observed for rates of all valve related morbidity: 2.6, 2.4 and 3.5%, respectively. Risk of thromboembolism increased with age, linearized rates were: 0.3, 0.7 and 1.3%. Risk of deterioration and reoperation decreased with age, rates of deterioration were 0.8, 0.1 and 0%. Other valve related events had the same incidence in all groups. No statistical difference was observed between group II and group III for deteriorations and reoperations. CONCLUSIONS: The performance of the Carpentier-Edwards pericardial valve is the same at 10 years in group II and III. This study supports the clinical use of this tissue valve in patients over 60 years. The results in group I are satisfactory, nevertheless, a more durable biological valve is needed for young patients. 相似文献
25.
T Ohki K Watanabe T Negoro K Aso Y Haga K Kasai M Kito N Maeda 《Canadian Metallurgical Quarterly》1997,6(3):219-224
Demonstration of the full extent of abnormality in patients with the Struge-Weber syndrome (SWS) is important for prognosis and in planning surgery to remove the seizure focus. We compared single-photon emission computed tomography (SPECT), MRI and CT in nine children under the age of 4 years with seizures as part of SWS, in an attempt to determine the optimal method of imaging in different clinical settings. Seven unilateral and two bilateral cases were studied by interictal 99mtechnetium hexamethylpropyleneamineoxime (HMPAO) SPECT, and contrast-enhanced CT and MRI, giving information on 11 abnormal hemispheres. All imaging modalities showed abnormalities in every child. Perfusion imaging showed focal regions of decreased uptake in 9 of 11 (82%) abnormal hemispheres and demonstrated a widespread decrease but no focal defect in 2; it also revealed crossed cerebellar diaschisis in 2 cases. CT demonstrated typical gyriform calcification in 9 of 11 (82%) affected hemispheres. Contrast-enhanced MRI showed more extensive involvement than contrast-enhanced CT in 5 of 11 (45%) cases. The area of hypoperfusion shown by SPECT was smaller than the area of contrast enhancement on MRI in 6 of 11 cases (55%), comparable in 3 (27%) and larger in 2 cases (18%). CT is sufficient to confirm the clinical diagnosis of SWS, but MRI frequently shows more extensive abnormal areas. 99mTc HMPAO imaging is a useful addition when it is important to know the full extent of the disease, for example prior to surgery. It is likely to detect areas of hypoperfusion, representing ischaemic regions, which may act as an epileptogenic focus and may not be shown by CT or MRI. 相似文献
26.
Takahiro Yokoyama Akito Masuhara Tsunenobu Onodera Hitoshi Kasai Hidetoshi Oikawa 《Synthetic Metals》2009,159(9-10):897-899
Core/shell hybridized nanocrystals composed of Ag nanoparticle core and polydiacetylene shell were fabricated successfully by means of “co-reprecipitation/microwave irradiation method”. The hybridized nanocrystals were characterized using transmission electron microscopy (TEM) observation and UV–vis absorption spectroscopy. UV–vis spectral measurements revealed that polydiacetylene shell was the red phase while π-conjugated backbone is distorted. Detailed mechanism of formation of the red phase was discussed. 相似文献
27.
Nakazawa M. Okamoto S. Omiya T. Kasai K. Yoshida M. 《Photonics Technology Letters, IEEE》2010,22(3):185-187
28.
Ohmori T Morita H Tanaka M Miyauchi K Kasai D Furukawa K Miyashita K Ogawa N Masai E Fukuda M 《Journal of Bioscience and Bioengineering》2011,111(4):437-442
Rhodococcus jostii RHA1 accumulates chlorobenzoates (CBA) during the degradation of polychlorinated biphenyls (PCBs). CBA degradation is considered one of the rate-limiting steps in the complete degradation of PCBs. To reduce the accumulation of CBAs, the upper pathway enzyme genes for PCB degradation of RHA1 were introduced into a CBA-degrading bacterium, Burkholderia sp. NK8. The resulting recombinant strain exhibited no biphenyl 2,3-dioxygenase (BphA) activity encoded by bphAaAbAcAd genes, which encode the large and small subunits of the terminal oxygenase component and the ferredoxin and reductase subunits responsible for electron transfer from NADH to the large subunit. The remaining enzyme genes involved in the transformation of biphenyl to benzoate, bphB2C1D1, which encode dehydrogenase, ring-cleavage dioxygenase and hydrolase, conferred activities to NK8. To obtain the BphA activity of RHA1 in NK8, sets of BphA genes were constructed by combining the bphAaAbAcAd genes of RHA1 and bphA3A4 of Pseudomonas pseudoalcaligenes KF707, encoding the ferredoxin and reductase subunits. Hybrid derivatives of BphA containing the KF707 bphA3 conferred BphA activity to NK8, and a derivative containing the RHA1 bphAaAb and KF707 bphA3A4 genes exhibited the highest BphA activity. A plasmid containing the RHA1 bphAaAb and KF707 bphA3A4 genes plus the RHA1 bphB2C1D1 genes was constructed and introduced into NK8. The resulting recombinant strain efficiently degraded 2-, 3- and 4-chlorobiphenyls with an apparent reduction in CBA accumulation in comparison to the recombinant mutant strain, which had an insertion in the cbeA gene to inactivate CBA dioxygenase. 相似文献
29.
Allan Abraham B. Padama Bhume Chantaramolee Hiroshi Nakanishi Hideaki Kasai 《International Journal of Hydrogen Energy》2014
The absorption of H atom in H-covered Pd(110) (1 × 2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H2 is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system. 相似文献
30.
Niobate nanosheets prepared by exfoliation of layered hexaniobate K4Nb6O17 were sequentially decorated with two noble metal nanoparticles, gold and silver, through two-step photochemical reactions. First, cationic bis(ethylenediamine)gold(III) ions were electrostatically adsorbed on the anionic niobate nanosheets, and reduced to gold nanoparticles by UV excitation of the photocatalytically active niobate nanosheets. Then, the surface plasmon band of the photodeposited gold nanoparticles was excited with visible light, by which the silver cations introduced to the system together with citrate anions were reduced to silver nanoparticles. Spectroscopic and transmission electron microscopic observations indicated the formation of morphologically different silver nanoparticles, for example nanorods and core-shell particles. 相似文献