全文获取类型
收费全文 | 2112篇 |
免费 | 70篇 |
国内免费 | 8篇 |
学科分类
工业技术 | 2190篇 |
出版年
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 43篇 |
2020年 | 25篇 |
2019年 | 39篇 |
2018年 | 42篇 |
2017年 | 33篇 |
2016年 | 49篇 |
2015年 | 44篇 |
2014年 | 62篇 |
2013年 | 119篇 |
2012年 | 102篇 |
2011年 | 133篇 |
2010年 | 118篇 |
2009年 | 129篇 |
2008年 | 126篇 |
2007年 | 118篇 |
2006年 | 97篇 |
2005年 | 75篇 |
2004年 | 86篇 |
2003年 | 70篇 |
2002年 | 56篇 |
2001年 | 41篇 |
2000年 | 42篇 |
1999年 | 39篇 |
1998年 | 58篇 |
1997年 | 39篇 |
1996年 | 37篇 |
1995年 | 26篇 |
1994年 | 29篇 |
1993年 | 21篇 |
1992年 | 25篇 |
1991年 | 26篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 22篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 19篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 16篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1974年 | 4篇 |
1972年 | 3篇 |
排序方式: 共有2190条查询结果,搜索用时 15 毫秒
81.
Masahiro Takahashi Yutaka Kimura Mitsuki Hagiwara Keiki Kishikawa Shigeo Kohmoto 《Synthetic Metals》2011,161(15-16):1557-1562
Improved synthesis and reinvestigation of the magnetic properties of triphenylamine bearing three nitronylnitroxide radicals (1) were carried out. Single crystal X-ray crystallographic analysis of 1 established that its molecular shape had a C3-symmetry. Our newly prepared 1 showed different physical properties from those of reported. SQUID measurements of 1 showed that each of the three spins of 1 behaved independently at room temperature. In contrast, the three spins coupled antiferromagnetically at lower temperature as low as ca. 1.8 K. These spin behaviors can be explained by a regular triangular antiferromagnetic model (J/kB = ?3.3 K) and interpreted as a spin frustration system. 相似文献
82.
Kiyoharu Nakagawa Hirokazu Oda Akira Yamashita Masahiro Okamoto Yoichi Sato Hidenori Gamo Mikka Nishitani-Gamo Kazuyuki Ogawa Toshihiro Ando 《Journal of Materials Science》2009,44(1):221-226
We developed a novel spherical carbon material. The spherical carbon is composed of a high density of carbon nanotubes or
nanofilaments, and includes an oxidized diamond particle as a core. Syntheses of this carbon in high volume with high selectivity
may be possible. It is expected that this carbon will be useful as a catalyst material for fuel cells, electric double-layer
capacitors, etc. 相似文献
83.
Konosuke Nishida Yasuo Yanagibashi Masahiro Osako 《The International journal of environmental studies》2013,70(3):237-249
The adoption of the sensory odor test will prevail widely in many local self governments in Japan in order to evaluate and regulate the complex odor in fields. This is also done by the tri‐angle choice bag test. However, this procedure has several problems in the reliability and reproducibility of the results obtained. It is desired to solve these problems by the mechanization of the method. From this point of view, an experimental study on the flow rate of test odor has been carried out and the results obtained are described in this paper. It is confirmed that the optimum flow rate of test odor is about 41/min at the inlet of the mask in the dynamic sniffing method. 相似文献
84.
Kei Masaki Yusuke K. Shibama Shinji Sakurai Masahiro Katayama Akira Sakasai 《Fusion Engineering and Design》2011,86(9-11):1872-1876
JT-60 is planned to be upgraded to JT-60SA tokamak machine with fully superconducting coils, which is a project of the JA-EU satellite tokamak program under both Broader Approach program and Japanese domestic program. The JT-60SA vacuum vessel (VV) has a D-shape poloidal cross section and a toroidal configuration with 10° facet segmented in toroidal direction. The material of the VV is 316L stainless steel with low cobalt content of <0.05 wt%. A double wall structure is adopted for the VV to ensure high rigidity and high toroidal one-turn resistance simultaneously.Fundamental welding R&D and a trial manufacturing of the 20° upper half of the VV have been performed to study the manufacturing procedure. After the confirmation of the quality of the mock-up, manufacturing of the actual VV started in November 2009. 相似文献
85.
Masahiro Nagae Tetsuo Yoshio Yoshito Takemoto Jun Takada 《Journal of the American Ceramic Society》2001,84(5):1175-1177
For pure molybdenum nitrided at 1373 K in NH3 gas, microstructural observations of a molybdenum nitride layer were conducted through a transmission electron microscope. The molybdenum nitride layer consisted of two molybdenum nitrides: an outer one of γ-Mo2 N and an inner one of β-Mo2 N. A great number of (011)[0 1] type twins were observed in the β-Mo2 N phase, whereas the microstructure of the γ-Mo2 N phase was almost free from lattice defects except for slightly observed {111}〈112〉 type twin. 相似文献
86.
Huan-Bang Li Takashi Takahashi Masahiro Toyoda Yasuyuki Mori Ryuji Kohno 《Wireless Personal Communications》2009,51(4):697-709
Wireless Body Area Network (WBAN) is expected to play an important role in supporting medical and healthcare services with
increased convenience and comfort. One main advantage of WBAN is that it enables automatic biosignal collection in real time
which is essential in medical treatment and healthcare vigilance. To harmonize with the strong demands from both medical and
healthcare societies, and information and communications technology industries, IEEE 802 Standard Committee set up a task
group of TG15.6 to develop an IEEE wireless standard on WBAN. In this paper, we first review the main activities of TG15.6
with the updated status. Then, we present a prototype WBAN system that is implemented by using ultra-wideband technology.
Multi-hop mechanism is adopted to guarantee reliable connection. Finally, we describe an experimental system that uses the
developed WBAN system by combining with satellite communication in supporting remote medical treatment and healthcare. In
case of less of medical resources such as in emergency, in rural or isolated areas, such a system is important in sending
the corresponding biosignal to a remote hospital in real time to help patient management. The relative delay of WBAN data
delivery via satellite is measured which is dependent on the satellite link capacity. 相似文献
87.
A model for simulating a long-term diffusion in concrete under submerged conditions has been developed. The model focuses on the interaction between cement hydrates and electrolyte solution adopting the physical properties of concrete as alternative parameters for estimating long-term diffusion. The model was verified by the large variety of long-term experimental data involving verification of cement hydrates, porosity properties, pH value, element distribution, and chloride penetration for sulphate-resistant Portland cement (SRPC) concretes. Evaluating impacts of hundreds of years’ exposure on concrete durability, a simulation was also performed for an exposure time of 500 years. The results confirmed the importance of ion–cement-hydrate interaction in the evaluation of a long-term diffusion of harmful substances such as chlorides into concrete. The simulation results show also that the solid phases of the SRPC concrete mix that was used are stable in the long-term. The threshold concentration of chlorides which may initiate reinforcement corrosion defined as Cl?/OH? ratio could be exceeded in concrete after moderate exposure period under the conditions investigated with typical protective concrete layers. Using of case-specific values for a threshold chloride content and evaluating the method used for estimating the initiation time of reinforcement corrosion are recommended in the structures with a long-design service life. 相似文献
88.
Masahiro Kotani Yusuke Yasufuku Naoki Inoue Ken Kurihara Hiroyuki Kawada 《Mechanics of Time-Dependent Materials》2013,17(2):261-274
This study aims to investigate the effects of a hydrothermal environment on the creep behavior of woven glass fiber reinforced plastics (GFRPs) and to propose a method for predicting their lifetime. Toward this end, experiments were carried out in air and deionized water at 40, 60, 80 and 95 °C. Static tensile tests of woven GFRP were conducted in air and in deionized water to evaluate its mechanical properties and to determine suitable experimental conditions for subsequent constant tensile load tests. The mechanical properties of the woven GFRP decreased with an increase in temperature and with water immersion. Constant tensile load tests were also conducted in air and in deionized water to investigate the creep behavior and fracture time. The fracture time decreased with an increase in stress and water temperature and demonstrated the possibility of a threshold stress for fracturing. In addition, the fracture time during each constant tensile load test was predicted using a modified Reiner–Weissenberg (R-W) criterion, which is a failure criterion for linear viscoelastic materials based on the accumulation of dissolved energy within the GFRP. In this study, the R-W criterion was modified to consider the effects of degradation and its acceleration, which are due to the applied stress and immersion in a solution. The predicted results were in good agreement with the experimental data when considering the effects of hydrothermal aging. 相似文献
89.
Shiplu Roy Chowdhury Yuichi Muneyuki Yasunori Takezawa Masahiro Kino-oka Atsuhiro Saito Yoshiki Sawa Masahito Taya 《Journal of Bioscience and Bioengineering》2010,109(3):310-313
The transitional behaviors of myoblasts toward differentiation were investigated in the cultures at the low and high seeding densities (respectively, X0 = 1.0 × 103 and 2.0 × 105 cells/cm2). In the culture at the low seeding density, an increase in confluence degree accompanied a decrease in growth potential (Rp), being Rp = 0.85 and 0.11 at t = 48 and 672 h, respectively. Myoblasts seeded at the high density resulted in the immediate cessation of growth with keeping the low range of Rp = 0.02–0.09 throughout the culture. The reduction of Rp led to the generation of three subpopulations of cells in proliferative, quiescent and differentiated states. Close cell contacts in the confluent state of high seeding culture induced cell quiescence to a higher extent with suppressing differentiation. 相似文献
90.