全文获取类型
收费全文 | 294篇 |
免费 | 20篇 |
专业分类
电工技术 | 13篇 |
化学工业 | 129篇 |
金属工艺 | 3篇 |
机械仪表 | 9篇 |
建筑科学 | 6篇 |
能源动力 | 7篇 |
轻工业 | 28篇 |
水利工程 | 1篇 |
无线电 | 19篇 |
一般工业技术 | 51篇 |
冶金工业 | 12篇 |
原子能技术 | 17篇 |
自动化技术 | 19篇 |
出版年
2022年 | 5篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 10篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 10篇 |
2009年 | 9篇 |
2008年 | 20篇 |
2007年 | 12篇 |
2006年 | 17篇 |
2005年 | 12篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 12篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有314条查询结果,搜索用时 15 毫秒
81.
Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning, recovery
from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins,
and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. In addition,
several natural food components have been found to show physiological effects, and some of them are considered to be useful
for promoting exercise performance or for prevention of injury. However, these foods should only be used when there is clear
scientific evidence and with understanding of the physiological changes caused by exercise. This article describes various
"functional foods" that have been reported to be effective for improving exercise performance or health promotion, along with
the relevant physiological changes that occur during exercise. 相似文献
82.
Fukushima T Kosaka A Yamamoto Y Aimiya T Notazawa S Takigawa T Inabe T Aida T 《Small (Weinheim an der Bergstrasse, Germany)》2006,2(4):554-560
Free-radical polymerization of an imidazolium ion-based ionic liquid bearing a methacrylate group, gelling with single-walled carbon nanotubes (SWNTs), allows fabrication of a mechanically reinforced, electroconductive soft material (bucky plastic). A film sample of this material displays an excellent conductivity of 1 S cm(-1) and a 120-fold enhancement of the Young's modulus at a 7 wt % content of SWNTs. The conductivity is temperature-dependent in the range 5-300 K, suggesting that the conductive process involves carrier hopping. Scanning electron and atomic force micrographs of a bucky plastic film display the presence of crosslinked networks consisting of finely dispersed SWNTs. Such nanotube networks, developed in the polymer matrix, likely suppress slipping of entrapped polymer molecules via a strong interfacial interaction and also facilitate intertubular carrier transport. Although a bucky plastic derived from a vinylimidazolium ion-based ionic liquid monomer shows a comparable conductivity to that of the methacrylate version, the film is brittle irrespective of the presence or absence of SWNTs. 相似文献
83.
Yasuhiro Watanabe Toshikazu Adachi Hirohiko Someya Shoichiro Koseki Shinichi Ogawa 《Electrical Engineering in Japan》2007,160(1):49-60
JAEA and KEK are jointly constructing the high‐intensity proton accelerator project J‐PARC. Its main accelerator is a 3‐GeV rapid cycling synchrotron (RCS). Two types of resonant excitation systems, parallel and cascade, are introduced to excite DC biased 25‐Hz AC currents through its main magnets. The parallel excitation is adopted for the dipole magnet power supply system, and the cascade excitations are adopted for the seven family quadrupole magnets system. In this paper, the two systems are investigated and analyzed, and an explanation is given as to why the different types are adopted in each system. The authors believe that such hybrid exciting systems are most suitable for a high‐power RCS. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(1): 49–60, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20535 相似文献
84.
Rina Maeda Dr. Toshikazu Bando Prof. Dr. Hiroshi Sugiyama 《Chembiochem : a European journal of chemical biology》2021,22(9):1538-1545
Pyrrole-imidazole (PI) polyamides, which target specific DNA sequences, have been studied as a class of DNA minor-groove-binding molecules. To investigate the potential of compounds for cancer treatment, PI polyamides were conjugated with DNA-alkylating agents, such as seco-CBI and chlorambucil. DNA-alkylating PI polyamides have attracted attention because of their sequence-specific alkylating activities, which contribute to reducing the severe side effects of current DNA-damaging drugs. Many of these types of conjugates have been developed as new candidates for anticancer drugs. Herein, we review recent progress into research on DNA-alkylating PI polyamides and their sequence-specific action on targets associated with cancer development. 相似文献
85.
Daisuke Segawa Maki Yoshida Shinji Nakaya Toshikazu Kadoka 《Microgravity science and technology》2005,17(3):23-30
For bridging between knowledge on droplet combustion and spray combustion, an experimental study was performed on autoignition
and combustion of multiple droplet clusters. The monodispersed suspended-droplet cluster (MSDC) model with which arrangement,
spacing and initial diameter of the droplet are well controlled has been developed. The effects of spacing and arrangement
of droplet on combustion characteristics of the MSDC model in a high-temperature air were examined using microgravity environment
in a drop shaft. The ignition delay and the burning time increased with decreasing the droplet spacing, regardless of the
droplet number and the model dimensions. Larger droplet number with three-dimensional (3D) hexagonal closest packing (HCP)
structure model resulted in longer ignition delay and longer burning time. 3D cubic closest packing (CCP) structure model
showed rather longer ignition delay and much shorter burning time than 2D model. For 3D HCP model, an individual flame which
enveloped each droplet was formed whole in the combustion duration with larger droplet spacing, while the group flame was
formed whole in the combustion duration with smaller droplet spacing. When the droplet spacing was in the intermediate range,
each droplet was ignited to form the individual flame, and each flame merged into the group flame. The diameter of the burning
sphere decreased at the beginning of combustion, and turned to increase afterward. The transition from the individual flame
to the group flame occurred around the time when the burning sphere diameter reached its minimum. The burning sphere diameter
relative to the model diameter increased with decreasing the droplet spacing in the middle stage of combustion. 相似文献
86.
Hybrid films of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) were prepared with different molecular weights of poly(ethylene oxide) (PEO). The cross-linking reaction between PEO and PEDOT:PSS was performed at high temperature and confirmed by using differential scanning calorimeter (DSC), contact angle measurement, and solid-state 1H NMR. The effect of chemical reaction on the conductivity and morphology of these hybrid films was studied by using 4-point probe and atomic force microscope (AFM), respectively. As-spun PEO/PEDOT:PSS films have lower electric conductivity due to the addition of nonconductive PEO, and exhibits no molecular weight dependence on conductivity. After chemical cross-linking reaction at high temperature, only PEDOT:PSS films with lowest molecular weight PEO additives show enhanced conductivity with increasing reaction time. AFM result indicates that the heat-treated PEO/PEDOT:PSS hybrid films show grain-like morphology compared to ethylene glycol treated PEDOT:PSS films which shows continuous PEDOT domain. In the present work we demonstrate that the cross-linking reaction can be used to improve the wet stability of PEDOT:PSS nanofiber, showing good water resistance and excellent dimensional stability. 相似文献
87.
88.
Cationic copolymerizations of vinyl ether monomers [2-methoxyethyl vinyl ether: MOVE, 2-(2-methoxyethoxy)ethyl vinyl ether: MEEVE, 2-adamantyl vinyl ether: AdVE, 2-(2-vinyloxyethoxy)ethyl methacrylate: VEEM] were performed to obtain three types of vinyl ether copolymers [poly(MOVE-AdVE)s, poly(MEEVE-AdVE)s, and poly(MEEVE-VEEM)s] with different composition rates. Poly(MOVE-AdVE) and poly(MEEVE-AdVE) obtained at monomer feed ratio of 1:1 exhibited the glass transition temperatures (Tg) of 55 and 28 °C, respectively, but the Tg's of copolymers were near or lower than room temperature when the feed ratio of AdVE decreased. Poly(MOVE-AdVE)s and poly(MEEVE-AdVE) with Tg's above room temperature afforded free-standing membranes by casting them from toluene solutions. They exhibited relatively high CO2 permeability and high CO2/N2 separation factors (P(CO2) = 22–36 barrers, P(CO2)/P(N2) = 19–40). The Tg's of poly(MEEVE-VEEM)s were very low and around ?70 °C irrespective of the difference of monomer feed ratio. Methacrylate groups in poly(MEEVE-VEEM)s partially reacted under heating to give crosslinked polymer membranes. The crosslinked membranes showed high CO2/N2 selectivity, especially the poly(MEEVE-VEEM) membrane possessing the highest ratio of MEEVE exhibited high CO2 permeability and high selectivity (P(CO2) = 120 barrers, P(CO2)/P(N2) = 55). 相似文献
89.
Kenneth R. Hobson David L. Wood Laurence G. Cool Peter R. White Toshikazu Ohtsuka Isao Kubo Eugene Zavarin 《Journal of chemical ecology》1993,19(9):1837-1846
The attraction of the red turpentine beetle,Dendroctonus valens, to the resin volatiles of its host,Pinus ponderosa, is elicited by three chiral monoterpenes. In field assays response was greatest to (S)-(–)--pinene; 92% (S)-(–)--pinene found inP ponderosa resin was not attractive. However, 75% (R)-(+)--pinene, which occurs inPinus lambertiana, a sympatric host ofD. valens, was attractive. (S)-(–)--Pinene interrupted response to (R)-(+)--pinene. (S)-(+)-3-Carene from both hosts was attractive at the (R)-(+)--pinene level. Three sympatric coniferous nonhosts each have the same attractive monoterpenes but produce less resin. These studies demonstrate the importance of chirality of host compounds in the host finding behavior of this bark beetle. 相似文献
90.
Toshikazu Kawaguchi Dhesingh Ravi Shankaran Sook Jin Kim Kiyoshi Matsumoto Kiyoshi Toko Norio Miura 《Sensors and actuators. B, Chemical》2008,133(2):467-472
In order to develop the fully integrated portable surface plasmon resonance (SPR) system for detection of explosives, the amplification strategy of SPR signal was investigated. Indirect competitive inhibition method allowed the middle-sized SPR sensor to detect trinitrotoluene (TNT) at ppt level. However, this enhanced SPR signal was not high enough to detect TNT at ppt level by a miniaturized SPR sensor. Therefore, localized surface plasmon resonance (LSPR) effect using Au nanoparticle as further signal amplification approach was used. The amplification method of indirect competitive inhibition and LSPR were combined together for fabrication of the immunosurface using Au nanoparticle. TNT detectable range of this immunosurface was from 10 ppt (10 pg/ml) to 100 ppb (100 ng/ml), which was almost comparable to that without Au nanoparticle. The observed resonance angle change due to binding monoclonal TNT antibody (M-TNT Ab) with the immunosurface modified with Au nanoparticle was amplified to four times higher than that in absence of Au nanoparticle. 相似文献