全文获取类型
收费全文 | 1285篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 99篇 |
综合类 | 3篇 |
化学工业 | 375篇 |
金属工艺 | 28篇 |
机械仪表 | 42篇 |
建筑科学 | 15篇 |
能源动力 | 185篇 |
轻工业 | 86篇 |
石油天然气 | 1篇 |
无线电 | 83篇 |
一般工业技术 | 168篇 |
冶金工业 | 137篇 |
原子能技术 | 25篇 |
自动化技术 | 67篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 18篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 38篇 |
2011年 | 79篇 |
2010年 | 50篇 |
2009年 | 52篇 |
2008年 | 63篇 |
2007年 | 56篇 |
2006年 | 41篇 |
2005年 | 44篇 |
2004年 | 48篇 |
2003年 | 52篇 |
2002年 | 37篇 |
2001年 | 21篇 |
2000年 | 25篇 |
1999年 | 23篇 |
1998年 | 76篇 |
1997年 | 52篇 |
1996年 | 46篇 |
1995年 | 25篇 |
1994年 | 28篇 |
1993年 | 25篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 10篇 |
1983年 | 16篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 10篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有1314条查询结果,搜索用时 31 毫秒
101.
Yoshihito Nakagawa Yukihiro Akao Kohei Taniguchi Akemi Kamatani Tomomitsu Tahara Toshiaki Kamano Naoko Nakano Naruomi Komura Hirokazu Ikuno Takafumi Ohmori Yasutaka Jodai Masahiro Miyata Mistuo Nagasaka Tomoyuki Shibata Naoki Ohmiya Ichiro Hirata 《International journal of molecular sciences》2015,16(1):1526-1543
Accumulating data indicates that certain microRNAs (miRNAs or miRs) are differently expressed in samples of tumors and paired non-tumorous samples taken from the same patients with colorectal tumors. We examined the expression of onco-related miRNAs in 131 sporadic exophytic adenomas or early cancers and in 52 sporadic flat elevated adenomas or early cancers to clarify the relationship between the expression of the miRNAs and the endoscopic morphological appearance of the colorectal tumors. The expression levels of miR-143, -145, and -34a were significantly reduced in most of the exophytic tumors compared with those in the flat elevated ones. In type 2 cancers, the miRNA expression profile was very similar to that of the exophytic tumors. The expression levels of miR-7 and -21 were significantly up-regulated in some flat elevated adenomas compared with those in exophytic adenomas. In contrast, in most of the miR-143 and -145 down-regulated cases of the adenoma-carcinoma sequence and in some of the de novo types of carcinoma, the up-regulation of oncogenic miR-7 and/or -21 contributed to the triggering mechanism leading to the carcinogenetic process. These findings indicated that the expression of onco-related miRNA was associated with the morphological appearance of colorectal tumors. 相似文献
102.
Functionally graded nano‐TiO2 epoxy matrix composites were successfully fabricated using a centrifugal method. In the preparation of the composite, the aggregation of nano‐TiO2 occurred during curing, which had a negative effect on the composite performance. To solve this problem, we introduced a silane coupling agent to modify the surface of the nano‐TiO2, thereby improving the performance and mechanical properties simultaneously. The modified nano‐TiO2 (s‐TiO2) had better dispersion in the epoxy resin, making it possible to produce depth gradients of the mechanical properties of functionally graded materials (FGMs). The s‐TiO2 was characterized with respect to functional groups, morphology, and chemical elements using transmission electron microscopy, X‐ray photoelectron spectroscopy, and Fourier‐transform infrared spectroscopy. The results show that a silane layer was successfully coated on the surface. Also, the gradients of the mechanical and permittivity properties of the FGM indicated that by modifying the surface of the nano‐filler, it is possible to fabricate nano‐filler‐reinforced epoxy matrix FGMs using a centrifugal method. POLYM. COMPOS., 35:557–563, 2014. © 2013 Society of Plastics Engineers 相似文献
103.
Role of Heavy Meromyosin in Heat‐Induced Gelation in Low Ionic Strength Solution Containing l‐Histidine 下载免费PDF全文
Toru Hayakawa Yuri Yoshida Masanori Yasui Toshiaki Ito Jun‐ichi Wakamatsu Akihito Hattori Takanori Nishimura 《Journal of food science》2015,80(8):C1641-C1645
The gelation of myosin has a very important role in meat products. We have already shown that myosin in low ionic strength solution containing l ‐histidine forms a transparent gel after heating. To clarify the mechanism of this unique gelation, we investigated the changes in the nature of myosin subfragments during heating in solutions with low and high ionic strengths with and without l ‐histidine. The hydrophobicity of myosin and heavy meromyosin (HMM) in low ionic strength solution containing l ‐histidine was lower than in high ionic strength solution. The SH contents of myosin and HMM in low ionic strength solution containing l ‐histidine did not change during the heating process, whereas in high ionic strength solution they decreased slightly. The heat‐induced globular masses of HMM in low ionic strength solution containing l ‐histidine were smaller than those in high ionic strength solution. These findings suggested that the polymerization of HMM molecules by heating was suppressed in low ionic strength solution containing l ‐histidine, resulting in formation of the unique gel. 相似文献
104.
Toshiaki Arai Narihiro Morosawa Kazuhiko Tokunaga Yasuhiro Terai Eri Fukumoto Takashige Fujimori Tatsuya Sasaoka 《Journal of the Society for Information Display》2011,19(2):205-211
Abstract— The stability and reliability of oxide‐semiconductor TFTs were investigated. The contact material to the oxide semiconductor affected the thermal stability of the TFT, and a molybdenum‐contact source/drain showed good stability. And the passivating film and TFT structure affected the stability against bias stress and humidity stress, and dc‐sputtered Al2O3 passivation and fully covered channel structure with an etching stopper or source/drain showed good reliability. Moreover, high photo‐stability was confirmed by the bias‐enhanced photo‐irradiation stress test. An 11.7‐in.‐diagonal qHD AMOLED display was demonstrated to provide an applicable solution for a large‐sized OLED and an ultra‐high‐definition LCD‐TV mass production. 相似文献
105.
106.
Hachijojima is a gourd-shaped volcanic island in the Pacific Ocean. Nishiyama and Higashiyama volcanoes consist of basalt lava and associated pyroclastic rocks. A promising geothermal resource was found in south Higashiyama, associated with an uplift of Tertiary rocks consisting of mainly andesite lava and related pyroclastic rocks, overlain by Quaternary volcanic rocks. Steep high-temperature (over 250°C) and high-pressure gradients occur in the deeper portion of the system near the Tertiary–Quaternary contact, indicating the presence of a cap rock. The cap rock formed by deposition of hydrothermal minerals. Geothermal fluid ascends from the deeper portions to shallow depths along vertical fractures through the cap rock. These vertical fractures form the geothermal reservoir in the Tertiary formation. Three wells were drilled into these vertical fractures, and approximately 30 t/h of superheated steam was obtained from each well during flow tests. The geothermal fluid is mainly a mixture of seawater and meteoric water in an approximate ratio of 1 to 2, based on chemical analyses, with a portion of volcanic gas included. At present a 3.3 MWe, geothermal power plant is being constructed here. 相似文献
107.
Lu Yang Tomohiro Yendo Mehrdad Panahpour Tehrani Toshiaki Fujii Masayuki Tanimoto 《Journal of Visual Communication and Image Representation》2010,21(5-6):542-560
In this paper, we present a new view synthesis method in multiview camera configurations of Free viewpoint TV (FTV) where potential depth errors are considered. The emphasis is on the artifacts eliminating for photorealistic synthesis especially near object boundaries. In contrast to conventional techniques which ignore geometry errors, we first categorize the artifact cases and depth modes. Furthermore, this paper infers the complementarity principle of the artifacts from left and right references. This complementarity guarantees the effectiveness of our reliability-based synthesis. The reliability reasoning is crucial for artifacts reduction. The reliable and unreliable areas from different views can be correctly labeled. Then artifacts caused by unreliable pixels from one reference can be replaced by the reliable pixels from the other reference. As a final result, artifacts of novel view are demonstrated to be significantly reduced on different multiview sequences. 相似文献
108.
Ali Dashti Ahmad Ramazani SA Yuichi Hiraoka Sang Yull Kim Toshiaki Taniike Minoru Terano 《Polymer International》2009,58(1):40-45
BACKGROUND: Kinetic and morphological aspects of slurry propylene polymerization using a MgCl2‐supported Ziegler–Natta catalyst synthesized from a Mg(OEt)2 precursor are investigated in comparison with a ball‐milled Ziegler–Natta catalyst. RESULTS: The two types of catalyst show completely different polymerization profiles: mild activation and long‐standing activity with good replication of the catalyst particles for the Mg(OEt)2‐based catalyst, and rapid activation and deactivation with severe fragmentation of the catalyst particles for the ball‐milled catalyst. The observed differences are discussed in relation to spatial distribution of TiCl4 on the outermost part and inside of the catalyst particles. CONCLUSION: The Mg(OEt)2‐based Ziegler–Natta catalyst is believed to show highly stable polymerization activity and good replication because of the uniform titanium distribution all over the catalyst particles. Copyright © 2008 Society of Chemical Industry 相似文献
109.
Yanyong Liu Toshiaki Hanaoka Tomohisa Miyazawa Kazuhisa Murata Kiyomi Okabe Kinya Sakanishi 《Fuel Processing Technology》2009,90(7-8):901-908
Fischer–Tropsch (F–T) synthesis was carried out in a gas-flowed slurry-phase reaction system over Mn- and Zr-modified Co/SiO2 catalysts. A 0.5 L stirred tank slurry reactor (STSR) was used for catalyst screening and a 12.5 L slurry bubble column reactor (SBCR) was used for trial pilot operation. While using the 0.5 L reactor for catalyst screening, Co supported on the SiO2 with an average pore size of 10 nm showed a high catalytic performance for the F–T synthesis due to the suitable Co particle size in the catalyst. Zr promoter improved the activity and Mn promoter improved the stability of Co/SiO2 catalyst for the F–T synthesis. H2-TPR profiles indicated that Zr and Mn promoters improved the reduction degree of Co3O4 particles (on SiO2 surface) to Co0 active species in H2 flow at low temperature. While using the 12.5 L reactor for trial pilot operation over Mn–Zr–Co/SiO2 catalyst, the space-time yield (STY) of C5+ hydrocarbons (liquid fuel) showed almost the same values when various solvents (n-C16H34, n-C14H30, diesel from petrol station, F–T crude oil) were used. Diesel and F–T crude oil are suitable for using in a large-scaled F–T synthesis plant owing to the low prices. Mn–Zr–Co/SiO2 catalyst achieved a STY of C5+ hydrocarbons larger than 1000 g-C5+ kg-cat? 1 h? 1 in the 12.5 L reactor. The production capacity of liquid fuel from the 12.5 L reactor reached to 15.6 L per day (assumed for 24 h continuous operation). The stirring was very important for the F–T synthesis both reaction in the 0.5 L reactor and reaction in the 12.5 L reactor. The shape of slurry reactor also influenced the CO conversion for the F–T synthesis: reaction in the 12.5 L SBCR gave a higher CO conversion than that of reaction in the 0.5 L STSR (at the same W/F value under the same stirring speed) because the slender column reactor (SBCR) extended the residue time of reaction gas in the slurry-phase containing catalyst. 相似文献
110.