全文获取类型
收费全文 | 474篇 |
免费 | 22篇 |
专业分类
电工技术 | 14篇 |
化学工业 | 170篇 |
金属工艺 | 21篇 |
机械仪表 | 7篇 |
建筑科学 | 7篇 |
能源动力 | 17篇 |
轻工业 | 32篇 |
石油天然气 | 2篇 |
无线电 | 51篇 |
一般工业技术 | 101篇 |
冶金工业 | 42篇 |
原子能技术 | 10篇 |
自动化技术 | 22篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 16篇 |
2017年 | 8篇 |
2016年 | 15篇 |
2015年 | 5篇 |
2014年 | 21篇 |
2013年 | 25篇 |
2012年 | 25篇 |
2011年 | 33篇 |
2010年 | 18篇 |
2009年 | 24篇 |
2008年 | 23篇 |
2007年 | 23篇 |
2006年 | 29篇 |
2005年 | 14篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 15篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有496条查询结果,搜索用时 437 毫秒
61.
Norimasa Kashiwagi Kohei Yamashita Hiroyuki Furuta Prof. Yoshiya Ikawa Prof. 《Chembiochem : a European journal of chemical biology》2009,10(17):2745-2752
The template effect plays important roles not only in modern synthetic and enzymatic catalysis but also in the ancient “RNA‐polypeptide (RNP) world,” which has been postulated to be a crucial stage in the origin of life. To mimic primitive template catalysis of peptide ligations by RNAs, we previously reported the design and synthesis of a ternary RNP complex in which the ligation of two peptides was significantly facilitated by a template RNA with two peptide‐binding units. However, RNA molecules also promoted the ligation reaction in a nonspecific manner through electrostatic interactions between RNA and basic peptides. In this study, we suppressed this effect by reducing the length of the original template derived from the Tetrahymena intron RNA. This modification, however, decreased the template ability for the specific reaction. As an alternative RNA that was as effective as the original template, we found that a self‐dimerizing RNA was a promising template for peptide ligation without a nonspecific effect. 相似文献
62.
We examined the structural features of muscle spindles at the equatorial and juxtaequatorial regions in the extensor digitorum longus muscle of adult (12 months) and aged (25 months) rats. In aged muscle spindles, the lamellated layers of the spindle capsule were a little increased in number compared to those in the adult ones. Two novel muscle spindles were observed in the aged muscle. In one muscle spindle, the spindle capsule contained four thin intrafusal muscle fibers invested by the inner capsule and two muscle fibers between the layers of the spindle capsule. Serial semithin sections revealed that the latter lacked the investment of the spindle capsule at the polar region. The other muscle spindle contained four intrafusal muscle fibers: two thin sensory-innervated muscle fibers invested by the inner capsule and two thick muscle fibers similar in structural features to neighboring extrafusal muscle fibers and lacking sensory innervation within the wide periaxial space. These findings suggest that two muscle fibers between the layers of the spindle capsule may be invested by the newly formed capsular cells during aging, while two thick fibers within the periaxial space may fail to receive the sensory innervation during the early development and follow the course of extrafusal fiber differentiation. 相似文献
63.
64.
65.
Kitaoka Haru Amano Ken-ichi Nishi Naoya Sakka Tetsuo 《Optimization and Engineering》2022,23(2):1033-1055
Optimization and Engineering - The Nelder-Mead (NM) method is a popular derivative-free optimization algorithm owing to its fast convergence and robustness. However, it is known that the method... 相似文献
66.
High‐Performance Dibenzoheteraborin‐Based Thermally Activated Delayed Fluorescence Emitters: Molecular Architectonics for Concurrently Achieving Narrowband Emission and Efficient Triplet–Singlet Spin Conversion
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Thermally activated delayed fluorescence (TADF) materials, which enable the full harvesting of singlet and triplet excited states for light emission, are expected as the third‐generation emitters for organic light‐emitting diodes (OLEDs), superseding the conventional fluorescence and phosphorescence materials. High photoluminescence quantum yield (ΦPL), narrow‐band emission (or high color purity), and short delayed fluorescence lifetime are all strongly desired for practical applications. However, to date, no rational design strategy of TADF emitters is established to fulfill these requirements. Here, an epoch‐making design strategy is proposed for producing high‐performance TADF emitters that concurrently exhibiting high ΦPL values close to 100%, narrow emission bandwidths, and short emission lifetimes of ≈1 µs, with a fast reverse intersystem crossing rate of over 106 s?1. A new family of TADF emitters based on dibenzoheteraborins is introduced, which enable both doped and non‐doped TADF‐OLEDs to achieve markedly high external electroluminescence quantum efficiencies, exceeding 20%, and negligible efficiency roll‐offs at a practical high luminance. Systematic photophysical and theoretical investigations and device evaluations for these dibenzoheteraborin‐based TADF emitters are reported here. 相似文献
67.
Xu Sugang Yoshikane Noboru Shiraiwa Masaki Tsuritani Takehiro Zhang Xiaocheng Awaji Yoshinari Wada Naoya 《Photonic Network Communications》2020,40(3):175-193
Photonic Network Communications - To achieve fast recovery of optical transport networks after a disaster, we investigate a novel scheme enabling cooperation between carriers. Carriers can take... 相似文献
68.
69.
Kaori Takemura Rina Watanabe Ryuji Kameishi Naoya Sakaguchi Hiroyuki Kamachi Atsushi Kume Ichirou Karahara Yuko T. Hanba Tomomichi Fujita 《Microgravity science and technology》2017,29(6):467-473
The photosynthetic and anatomical responses of bryophytes to changes in gravity will provide crucial information for estimating how these plant traits evolved to adapt to changes in gravity in land plant history. We performed long-term hypergravity experiments at 10g for 4 and 8 weeks using the moss Physcomitrella patens with two centrifuges equipped with lighting systems that enable long-term plant growth under hypergravity with irradiance. The aims of this study are (1) to quantify changes in the anatomy and morphology of P. patens, and (2) to analyze the post-effects of hypergravity on photosynthesis by P. patens in relation to these changes. We measured photosynthesis by P. patens for a population of gametophores (e.g., canopy) in Petri dishes and plant culture boxes. Gametophore numbers increased by 9% for a canopy of P. patens, with 24–27% increases in chloroplast sizes (diameter and thickness) in leaf cells. In a canopy of P. patens, the area-based photosynthesis rate (A canopy) was increased by 57% at 10g. The increase observed in A canopy was associated with greater plant numbers and chloroplast sizes, both of which involved enhanced CO2 diffusion from the atmosphere to chloroplasts in the canopies of P. patens. These results suggest that changes in gravity are important environmental stimuli to induce changes in plant growth and photosynthesis by P. patens, in which an alteration in chloroplast size is one of the key traits. We are now planning an ISS experiment to investigate the responses of P. patens to microgravity. 相似文献
70.
Gyo Kitahara Mitsuhiro Ikawa Satoshi Matsuoka Shunto Arai Tatsuo Hasegawa 《Advanced functional materials》2021,31(52):2105933
Semiconducting π-conjugated polymers are the most promising candidates for flexible electronics owing to their facile processability and mechanical robustness; however, achieving steep and stable switching operations in polymer thin-film transistors (TFTs) remains a serious challenge. Herein, it is shown that whole optimizations for eliminating interfacial carrier traps throughout the conductive path are necessary in achieving TFTs showing both exceptionally sharp switching and bias-stress-free characteristics. Inverted-coplanar-type TFTs composed of a highly lyophobic amorphous perfluoropolymer gate–dielectric interfaced with a push-coated semiconducting polymer layer are manufactured. The use of the dielectric allows the establishment of bias-stress-free characteristics with minimized contact resistance. Additionally, fairly sharp on/off switching TFTs with the smallest normalized subthreshold swing can be obtained by utilizing a particular donor–acceptor copolymer that involves a self-passivation mechanism working to achieve a trap-minimized interface. These findings have opened a way for low-power and robust device operations in polymer-based flexible electronics. 相似文献