全文获取类型
收费全文 | 1234篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 82篇 |
综合类 | 6篇 |
化学工业 | 280篇 |
金属工艺 | 36篇 |
机械仪表 | 46篇 |
建筑科学 | 16篇 |
能源动力 | 90篇 |
轻工业 | 87篇 |
水利工程 | 2篇 |
无线电 | 106篇 |
一般工业技术 | 217篇 |
冶金工业 | 111篇 |
原子能技术 | 53篇 |
自动化技术 | 134篇 |
出版年
2023年 | 5篇 |
2022年 | 22篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 20篇 |
2016年 | 23篇 |
2015年 | 21篇 |
2014年 | 34篇 |
2013年 | 66篇 |
2012年 | 41篇 |
2011年 | 67篇 |
2010年 | 52篇 |
2009年 | 61篇 |
2008年 | 72篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 56篇 |
2004年 | 55篇 |
2003年 | 46篇 |
2002年 | 33篇 |
2001年 | 30篇 |
2000年 | 25篇 |
1999年 | 24篇 |
1998年 | 41篇 |
1997年 | 49篇 |
1996年 | 39篇 |
1995年 | 23篇 |
1994年 | 20篇 |
1993年 | 13篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 4篇 |
1974年 | 6篇 |
1972年 | 3篇 |
排序方式: 共有1266条查询结果,搜索用时 15 毫秒
101.
Haruhisa Kato Ayako Nakamura Masanori Horie Shigehisa Endoh Katsuhide Fujita Hitoshi Iwahashi Shinichi Kinugasa 《Carbon》2011,(12):3989-3997
Stable dispersions of carbon black and nanodiamond in culture medium were prepared by adding a pre-mixed dispersion of commercial carbon black or nanodiamond in aqueous bovine serum albumin (BSA) solution to culture medium. Dynamic light scattering revealed that carbon black and nanodiamond dispersions prepared in both NaCl solution and culture medium were highly stable. From DLVO theory and the results of zeta potential measurements, the theoretical effect of the electrostatic interactions between adsorbed BSA molecules was found to be minimal. The asymmetric flow field-flow fractionation measurements revealed that 0.05 or 0.56 mg/mL of BSA molecules were adsorbed on 0.11 or 1.09 mg/mL of carbon black, respectively, indicating 1:2 complexation of BSA with the colloidal particles. In the case of nanodiamond, 0.06 or 0.60 mg/mL of BSA molecules were adsorbed on 0.10 or 1.05 mg/mL of nanodiamond, respectively, indicating 1:2 complexation of BSA, which is the same ratio as in the case of carbon black. The adsorbed BSA molecules served as an effective stabilizing agent for the carbon black and nanodiamond, ensuring dispersion stability for at least 1 week. The preparation of the dispersions can be easily carried out by other researchers for toxicity studies. 相似文献
102.
Norihisa Saeki Hiromi Sakamoto Teruhiko Yoshida 《International journal of molecular sciences》2014,15(5):7958-7973
Gastric cancer (GC) is one of the major malignant diseases worldwide, especially in Asia. It is classified into intestinal and diffuse types. While the intestinal-type GC (IGC) is almost certainly caused by Helicobacter pylori (HP) infection, its role in the diffuse-type GC (DGC) appears limited. Recently, genome-wide association studies (GWAS) on Japanese and Chinese populations identified chromosome 1q22 as a GC susceptibility locus which harbors mucin 1 gene (MUC1) encoding a cell membrane-bound mucin protein. MUC1 has been known as an oncogene with an anti-apoptotic function in cancer cells; however, in normal gastric mucosa, it is anticipated that the mucin 1 protein has a role in protecting gastric epithelial cells from a variety of external insults which cause inflammation and carcinogenesis. HP infection is the most definite insult leading to GC, and a protective function of mucin 1 protein has been suggested by studies on Muc1 knocked-out mice. 相似文献
103.
Matrix influence on the piezoelectric properties of piezoelectric ceramic/polymer composite exhibiting particle alignment 下载免费PDF全文
Shogo Mamada Naoyuki Yaguchi Masanori Hansaka Masafumi Yamato Hirohisa Yoshida 《应用聚合物科学杂志》2015,132(15)
This study was addressed to the influence of an electric field strength applied at fabrication process and matrix properties, such as the dielectric constant and the Young's modulus, on “pseudo‐1‐3 piezoelectric ceramic/polymer composite” in order to further enhance the piezoelectricity of that. The pseudo‐1‐3 piezoelectric ceramic/polymer composite consists of linearly ordered piezoelectric ceramic particles in polymer material. Silicone gel, silicone rubber, urethane rubber, and poly‐methyl‐methacrylate, which exhibit different dielectric constants and Young's modulus, were used as matrices to evaluate the matrix influence. The piezoelectricity of the pseudo‐1‐3 piezoelectric ceramic/polymer composite was evaluated using the piezoelectric strain constant d33. The d33 is one of the indices of the piezoelectric properties for piezoelectric materials. As a result, it was confirmed that d33 of the pseudo‐1‐3 piezoelectric ceramic/polymer composite increased with the increase of the electric filed strength applied at fabrication process, though, it reached a constant value at a certain strength value. Further it was confirmed that dielectric constant of the matrix had a small influence on d33 of the pseudo‐1‐3 piezoelectric ceramic/polymer composite, however, in case of matrix of lower Young's modulus, d33 was increase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41817. 相似文献
104.
Taeko Izumi Yoshihiro Yagimuma Masanori Haga 《Journal of the American Oil Chemists' Society》1997,74(7):875-878
Enyzmatic amidation of the primary amines β-alanine ethyl ester and 3-aminopropionitrile with methyl laurate by means of immobilized
lipase (Candida antarctica lipase, CAL) resulted in the formation in good yield of N-lauroyl-β-alanine ethyl ester and 3-(N-lauroylamino)-propionitrile, respectively. When 3-amino-propionitrile was used as substrate, diisopropyl ether was a suitable
solvent. Changing the reaction temperature (12–80°C) did not affect the yields, and room temperature was a suitable temperature
for this reaction. In the investigation of reaction conditions, the use of equimolar amounts (5 mmol) of substrate and ester,
along with 0.5 g of CAL, in diisopropyl ether gave the best yield (99.3%) after 24 h of incubation at 24°C. The enzyme activity
in the amidation reaction did not decrease even after six uses. With β-alanine ethyl ester hydrochloride as substrate, diisopropyl
ether was unsuited as a solvent owing to the low solubility of the substrate in this solvent.
In this reaction, the best yield (82.0%) was attained by using dioxane as solvent. CAL achieved higher extents of amide synthesis
with long-chain than with short-chain ester substrates. The enzyme accepted only nonbulky primary amines as substrates. 相似文献
105.
106.
Shiro Yamamoto Keiji Saeki Kazunari Takebayashi Yasunori Tashiro Masatoshi Kawasaki 《International Journal of Cast Metals Research》2013,26(1):1-8
The exacting quality required of hemispherical heavy-walled steel castings, used in nuclear power applications, has been remarkably improved by the adoption of a newly developed metal-mould process. This technique is dependent on the use of a metal core. The optimum conditions for solidification were determined by the finite element analytical method. The appropriate wall-thickness of the chill elements was also investigated using data based on actual experience. The core was designed in such a manner that the surface carried a series of concave “dimples” in the manner of a golf-ball, the pattern being intended to prevent the formation of cracks, generated on the casting surface when in contact with a metal mould. Stresses caused by solidification shrinkage were reduced by splitting the core. In the event, the casting structure conformed well to the results of the solidification analysis. Radiographic examination revealed a high level of soundness, with no trace of internal defects. No anisotropy was detected in mechanical properties. It is shown that this process is being currently employed in the manufacture of actual products. 相似文献
107.
Masami Kashiwa Shintaro Nishimoto Kazuaki Takahashi Michihiko Ike Masanori Fujita 《Journal of Bioscience and Bioengineering》2000,89(6):528
High concentrations of soluble selenium, selenate and selenite, have acute and chronic toxicity toward living things. With the aim of developing a biological process for selenium removal, the effects of a variety of parameters on the reduction of soluble selenium by a Bacillus sp. strain SF-1, which is capable of reductively transforming selenate into selenite and, subsequently, into nontoxic insoluble elemental selenium, were studied. The bacterial strain could effectively reduce 20 mM of selenate to selenite and 2 mM of selenite to elemental selenium in the presence of an appropriate carbon source and in the absence of oxygen. The reduction rate of selenate to selenite was much higher than that of selenite to elemental selenium, resulting in the transient accumulation of selenite during selenate reduction. The selenate reduction rate increased with increases in the selenate concentration up to 20 mM, while the rate of selenite reduction decreased sharply at selenite concentrations of more than 2 mM. The elemental selenium transformed from selenate via selenite was found both inside and outside the cells. Bacillus sp. SF-1 was able to utilize a variety of organic acids or sugars as a carbon source in selenate reduction. Although the copresence of sulfate did not inhibit selenate reduction, it was completely inhibited by some other oxyanions, including nitrate. A model sequencing batch system using the bacterial strain was developed and exhibited good performance in the treatment of wastewater containing high concentrations of selenate. 相似文献
108.
109.
Wei Zhang Kenji Ochi Michiya Fujiki Masanobu Naito Masaaki Ishikawa Kei‐ichi Kaneto Wataru Takashima Akinori Saeki Shu Seki 《Advanced functional materials》2010,20(22):3941-3947
In this paper a simple, casting solution technique for the preparation of two‐dimensional (2D) arrays of very‐high molecular weight (MW) 1D‐Pc supramolecular inorganic polymers is described. The soluble fluoroaluminium tetra‐tert‐butylphthalocyanine (ttbPcAlF) is synthesized and characterized, which can be self‐assembled to form 2D arrays of very‐high‐MW 1D‐Pc supramolecular inorganic polymers. High‐resolution transmission electron microscopy (HRTEM) demonstrates that the 1D‐ttbPcAlF, having a cofacial ring spacing of ~0.36 nm and an interchain distance of ~1.7 nm, self‐assembles into 2D‐nanosheets (~140 nm in length, ~20 nm in width, and equivalent to MW of 3.2 × 105 g mol?1). The film cast from a 1,2‐dichloroethane (DCE) solution shows a minimum hole‐mobility of ~0.3 cm2 V?1 s?1 at room temperature by flash‐photolysis time‐resolved microwave conductivity (TRMC) measurements and a fairly high dark dc‐conductivity of ~1 × 10?3 S cm?1. 相似文献
110.
In this paper, a microrobot soccer-playing game, such as that of MIROSOT (Microrobot World Cup Soccer Tournament), is adopted
as a standard test bed for research on multiple-agent cooperative systems. It is considerably complex and requires expertise
in several difficult research topics, such as mobile microrobot design, motor control, sensor technology, intelligent strategy
planning, etc., to build up a complete system to play the game. In addition, because it is an antagonistic game, it appears
ideal to test whether one method is better than other. To date there have been two different kinds of architecture for building
such system. One is called vision-based or centralized architecture, and the other is known as robot-based or decentralized
architecture. The main difference between them lies in whether there exists a host computer system which responds to data
processing and strategy planning, and a global vision system which can view the whole playground and transfer the environment
information to the host computer in real time. We believe that the decentralized approach is more advanced, but in the preliminary
step of our study, we used the centralized approach because it can lighten any overload of the microrobot design. In this
paper, a simplified layer model of the multiple-agent cooperative system is first proposed. Based on such a model, a system
for a microrobot soccer-playing game is organized. At the same time a simple genetic algorithm (SGA) is used for the autonomous
evolution of cooperative behavior among microrobots. Finally, a computer simulation system is introduced and some simulated
results are explained.
This work was presented, in part, at the Third International Symposium on Artificial Life and Robotics, Oita, Japan, January
19–21, 1998. 相似文献