全文获取类型
收费全文 | 2582篇 |
免费 | 87篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 162篇 |
综合类 | 3篇 |
化学工业 | 710篇 |
金属工艺 | 84篇 |
机械仪表 | 67篇 |
建筑科学 | 85篇 |
能源动力 | 113篇 |
轻工业 | 247篇 |
水利工程 | 12篇 |
石油天然气 | 8篇 |
武器工业 | 2篇 |
无线电 | 141篇 |
一般工业技术 | 531篇 |
冶金工业 | 191篇 |
原子能技术 | 66篇 |
自动化技术 | 255篇 |
出版年
2023年 | 9篇 |
2022年 | 6篇 |
2021年 | 67篇 |
2020年 | 27篇 |
2019年 | 38篇 |
2018年 | 44篇 |
2017年 | 43篇 |
2016年 | 65篇 |
2015年 | 38篇 |
2014年 | 91篇 |
2013年 | 185篇 |
2012年 | 147篇 |
2011年 | 155篇 |
2010年 | 137篇 |
2009年 | 161篇 |
2008年 | 140篇 |
2007年 | 124篇 |
2006年 | 103篇 |
2005年 | 94篇 |
2004年 | 76篇 |
2003年 | 55篇 |
2002年 | 65篇 |
2001年 | 44篇 |
2000年 | 53篇 |
1999年 | 47篇 |
1998年 | 96篇 |
1997年 | 53篇 |
1996年 | 59篇 |
1995年 | 35篇 |
1994年 | 39篇 |
1993年 | 44篇 |
1992年 | 25篇 |
1991年 | 25篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 29篇 |
1985年 | 27篇 |
1984年 | 23篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 15篇 |
1978年 | 6篇 |
1977年 | 17篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1971年 | 6篇 |
排序方式: 共有2677条查询结果,搜索用时 125 毫秒
71.
Kazuko Yamasaki Kenneth J. Mackin Masanori Ohshiro Kotaro Matsushita Eiji Nunohiro 《Artificial Life and Robotics》2008,12(1-2):122-124
We studied the networks of the temperature record in the atmosphere. They are made by the strength of the synchronization,
including the delay between temperatures at locations on Earth. We consider these locations as nodes, and we consider a pair
of locations as a link if the synchronization between them is stronger than a threshold. The network is scale-free, which
is thought to contribute to the stability of the climate.
This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January
25–27, 2007 相似文献
72.
Watanabe M Takemasa I Kawaguchi N Miyake M Nishimura N Matsubara T Matsuo E Sekimoto M Nagai K Matsuura N Monden M Nishimura O 《Proteomics. Clinical applications》2008,2(6):925-935
In the development of novel biomarkers, the proteomic approach is advantageous because using it the cancer-associated proteins can be directly identified. We previously developed a 2-nitrobenzenesulfenyl (NBS) method to improve quantitative proteome analysis. Here, we applied this method to proteomic profiling of colorectal carcinoma (CRC) to identify novel proteins with altered expression in CRC. Each pair of tumor and normal tissue specimens from 12 CRC patients was analyzed, and approximately 5000 NBS-labeled paired peaks were quantified. Peaks with altered signal intensities (>1.5-fold) and occurring frequently in the samples (>70%) were selected, and 128 proteins were identified by MS/MS analyses as differentially expressed proteins in CRC tissues. Many proteins were newly revealed to be CRC related; 30 were reported in earlier studies of CRC. Six proteins that were up-regulated in CRC (ZYX, RAN, RCN1, AHCY, LGALS1, and VIM) were further characterized and validated by Western blot and immunohistochemistry. All six were found to be CRC-localized, either in cancer cells or in stroma cells near the cancer cells. These results indicate that the proteins identified in this study are novel candidates for CRC markers, and that the NBS method is useful in proteome mining to discover novel biomarkers. 相似文献
73.
Tajima K Orisaka M Yata H Goto K Hosokawa K Kotsuji F 《Microscopy research and technique》2006,69(6):450-458
We developed a culture system in which two types of ovarian follicular cells were allowed to attach to opposite sides of a collagen membrane. Using this in vitro cell culture system, we studied the effects of granulosa- and theca-cell interaction on the morphology, structure, and function of bovine ovarian follicular cells. In the first part of the study, we explored how the interaction between theca and granulosa cells affects the morphology and structure of the cells. This study was done using follicular cells collected from bovine ovarian follicles at the early developmental stage. Granulosa cells cultured alone were flattened, and formed a monolayer sheet. By contrast, granulosa cells cultured with theca cells were convex, and formed multilayer sheets. Theca cells cultured alone were thin, flat, and spindle-shaped. Theca cells cultured with granulosa cells were also spindle-shaped; however, they appeared convex and more densely packed when compared with theca cells cultured alone. In the second part of the study, the possible role of the cellular interaction in the control of differentiation and growth of granulosa and theca cells was investigated. When follicular cells were isolated from the early stage of follicular development, theca cells reduced progesterone and inhibin production by granulosa cells and augmented the growth of granulosa cells. When the cells were isolated from the late stage of follicular development, by contrast, theca cells augmented hormonal production by granulosa cells, and did not affect the growth of granulosa cells. The growth and androstenedione production by theca cells were increased by the presence of granulosa cells, irrespective of the origin of follicular cells. These results demonstrated that communication between two types of follicular cells results in reciprocal modulation of their morphology, structure, growth, and function. Cellular interactions seem to be one of the major factors controlling the differentiation and growth of the follicular cells during the follicular maturation process. In contrast to granulosa and theca cells cultured alone, cells in the coculture seemed to possess morphological and functional characteristics more similar to those of cells in the growing follicular wall in vivo. Thus, we speculate that the interaction between these two types of follicular cells is essential for the maintenance of original structure and function of the bovine follicular wall. 相似文献
74.
Norman Makoto Su Hiroko N. Wilensky David F. Redmiles 《Computer Supported Cooperative Work (CSCW)》2012,21(2-3):111-162
We explore how the notion of communities of practice (CoPs) was translated and popularized from its original inception by Lave and Wenger in 1991. We argue that the Institute for Research on Learning (IRL), a spin-off of Xerox PARC, proved instrumental in enrolling CoPs into the knowledge management (KM) discipline. IRL objectified, packaged, and made a business out of CoPs. CoPs in KM are now a formalized process coupled with technological artifacts to build groups of people who effectively share knowledge across boundaries. Drawing from participant observations, archival documents, and interviews with KM practitioners in the aerospace industry as well as key players of IRL, our research seeks to unveil the invisible history that the popularization of a theory can often obscure. We argue that CoPs provide a case study for understanding how abstract concepts in science are strategically and subconsciously reified, or made objects of inquiry, and appropriated by actors. This reification of a “soft” science blurs the line between theory and technology. 相似文献
75.
Summary
Copolymerization of vinyl chloride (VC) and ethylene with Cp*Ti( OCH3)3/MAO catalyst was investigated. The Cp*Ti( OCH3)3/MAO catalyst initiated the copolymerization of VC with ethylene, although the copolymer yields were low. In the 13C NMR spectra of the copolymers, the peaks based on junction part between VC and ethylene was observed, but the signals were
small. From DSC measurement of the copolymers, only one glass transition temperature was observed. Thus, it is clear that
the copolymerization with Cp*Ti( OCH3)3/MAO catalysts gave the copolymer, and the copolymer consisting of block sequence rather than random copolymer.
Received: 13 November 2002/Revised: 6 January 2003/Accepted: 10 January 2003
Correspondence to Kiyoshi Endo 相似文献
76.
Toru Yamaguchi Makoto Sato Tomohiro Takagi 《Journal of Intelligent and Robotic Systems》1998,23(2-4):183-199
This paper proposes a multi-agent system that carries out cooperative work. To achieve this, we use Fuzzy Associative Memory Organizing Unit Systems (FAMOUS) and Conceptual Fuzzy Sets (CFS). By using these proposed methods, each agent robot can decide its own behaviour to suit the situation in its environment. We apply this system to an Intelligent Transportation System (ITS) and do simulations. 相似文献
77.
Sensor Fusion System Using Recurrent Fuzzy Inference 总被引:1,自引:0,他引:1
Futoshi Kobayashi Fumihito Arai Toshio Fukuda Koji Shimojima Makoto Onoda Norimasa Marui 《Journal of Intelligent and Robotic Systems》1998,23(2-4):201-216
In robotic and manufacturing systems, it is difficult to measure the state of systems accurately because of many uncertain factors and noise, and it is very important to estimate the state of systems. We must measure the phenomena of systems by multiple sensors and estimate the state of systems by acquiring information of sensors. However, we can not acquire all of sensor information synchronically, because each sensor has particular sensor information and measuring time. For estimating the state of systems by multiple sensors, a multi-sensor fusion system fusing various sensory information is needed. In this paper, we propose a Recurrent Fuzzy Inference (RFI) with recurrent inputs and apply it to a multi-sensor fusion system for estimating the state of systems. The membership functions of RFI are expressed by Radial Basis Function (RBF) with insensitive ranges. The shape of the membership functions can be adjusted by a learning algorithm. The learning algorithm is based on the steepest descent method and incremental learning which can add new fuzzy rules. The effectiveness of the multi-sensor fusion system using RFI will be shown through a numerical experiment of moving robot and estimation of surface roughness in grinding process. 相似文献
78.
Carbon nanotubes (CNTs) were produced by laser ablation of a graphite composite target in argon and nitrogen ambient gas. To investigate the effect of nitrogen gas on CNTs formation, the plasma plume was examined using optical emission spectroscopy. The vibrational temperature of C2 molecules was estimated by fitting of a Swan band spectrum. The temperature in N2 ambient gas is lower than that in Ar ambient gas. In a nitrogen atmosphere, the spectrum intensity of C2 Swan band was enhanced and CN violet system was also observed. Soot collected in the reaction tube was observed using FE-SEM and TEM. The soot deposited in the nitrogen gas contained more bundled CNTs than those in Ar ambience. 相似文献
79.
Hiroshige Kikura Junichiro Matsushita Mitsuo Matsuzaki Yuji Kobayashi Masanori Aritomi 《Science and Technology of Advanced Materials》2004,5(5-6):703
This paper reports the experimental research on thermal behaviour and particle size evaluation of primary clusters of ferromagnetic nano-particles in a water-based magnetic fluid. The magnetic fluids are suspensions of ultra fine particles coated with a molecular layer of dispersant in a liquid carrier such as water or kerosene. The particles are coated with single- or double-layer of surfactant to achieve stable dispersion. Numerous experimental studies have indicated the existence of the primary cluster of ferromagnetic nano-particles in a water-based magnetic fluid. The purpose of this research is to evaluate the particle size of the primary clusters by applying the Einstein's equation for Brownian motion assuming that the primary cluster has a spherical-shape. The thermal behaviour of ferromagnetic nano-particles in magnetic fluids is investigated through the micro visualization using the optical darkfield microscope system and particle tracking velocimetry data processing system. Real-time visualization of the Brownian motion of primary clusters in a water-based magnetic fluid was carried out. The experimental results clarified that the primary cluster size depends upon the concentration of the ferromagnetic nano-particle in the magnetic fluid. 相似文献
80.
One-step route to a hybrid TiO2/TixW1?xN nanocomposite by in situ selective carbothermal nitridation
Zo? Schnepp Martin J Hollamby Masahiko Tanaka Yoshitaka Matsushita Yoshio Katsuya Yoshio Sakka 《Science and Technology of Advanced Materials》2012,13(3)
Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/TixW1−xN) was synthesized by an ammonia-free sol–gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5 nm diameter) of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/TixW1−xN at low W content to an isostructural mixture of Ti-rich and W-rich TixW1−xN at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide. 相似文献