全文获取类型
收费全文 | 1658篇 |
免费 | 35篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 64篇 |
综合类 | 1篇 |
化学工业 | 312篇 |
金属工艺 | 50篇 |
机械仪表 | 39篇 |
建筑科学 | 38篇 |
能源动力 | 57篇 |
轻工业 | 117篇 |
水利工程 | 5篇 |
石油天然气 | 8篇 |
无线电 | 233篇 |
一般工业技术 | 199篇 |
冶金工业 | 412篇 |
原子能技术 | 32篇 |
自动化技术 | 129篇 |
出版年
2023年 | 7篇 |
2021年 | 25篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 25篇 |
2017年 | 23篇 |
2016年 | 21篇 |
2015年 | 19篇 |
2014年 | 30篇 |
2013年 | 61篇 |
2012年 | 54篇 |
2011年 | 71篇 |
2010年 | 57篇 |
2009年 | 65篇 |
2008年 | 50篇 |
2007年 | 54篇 |
2006年 | 47篇 |
2005年 | 41篇 |
2004年 | 38篇 |
2003年 | 52篇 |
2002年 | 49篇 |
2001年 | 39篇 |
2000年 | 41篇 |
1999年 | 44篇 |
1998年 | 151篇 |
1997年 | 95篇 |
1996年 | 86篇 |
1995年 | 51篇 |
1994年 | 43篇 |
1993年 | 46篇 |
1992年 | 20篇 |
1991年 | 31篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 17篇 |
1985年 | 27篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1972年 | 5篇 |
1971年 | 2篇 |
排序方式: 共有1696条查询结果,搜索用时 265 毫秒
1.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献
2.
Photocatalysts have attracted great research interest owing to their excellent properties and potential for simultaneously addressing challenges related to energy needs and environmental pollution. Photocatalytic particles need to be in contact with their respective media to exhibit efficient photocatalytic performances. However, it is difficult to separate nanometer-sized photocatalytic materials from reaction media later, which may lead to secondary pollution and a poor recycling performance. Hydrogel photocatalysts with a three-dimensional (3D) network structures are promising support materials for photocatalysts based on features such as high specific surface areas and adsorption capacities and good environmental compatibility. In this review, hydrogel photocatalysts are classified into two different categories depending on their elemental composition and recent progresses in the methods for preparing hydrogel photocatalysts are summarized. Moreover, current applications of hydrogel photocatalysts in energy conversion and environmental remediation are reviewed. Furthermore, a comprehensive outlook and highlight future challenges in the development of hydrogel photocatalysts are presented. 相似文献
3.
Hiromi Nakano 《Advanced Powder Technology》2019,30(10):2003-2013
In the Li2O–M2O5–TiO2 (M = Nb or Ta) system, Li1+x-yM1-x-3yTix+4yO3 (LMT) forms with a superstructure known as the M-phase, in which the periodical intergrowth layers are inserted in a matrix having a trigonal structure of LiMO3. We have been investigating this unique material focusing on its crystal structure, photoluminescence, and electrical properties.First, the formation area of the superstructure was compared between Nb- and Ta- systems and the difference was accurately analyzed.Second, to apply this unique material as a host material of phosphor, we synthesized new phosphors with various emission colors. Red phosphor, having a high PL intensity with an internal quantum efficiency of 98%, was successfully synthesized and used as a host material of the solid solution for the Ta system. Its high value was the result of the large centroid-to-cation distance of the Eu3+ position in the [(Li, Eu)O12] polyhedral.Further still, toward application of the unique qualities of an electro-ceramic, we successfully fabricated oriented balk ceramics for the Nb system by slip casting in a strong magnetic field of 12 T. As a result, anisotropic electric properties were found along the c-axis, which were caused by the superstructure. We first clarified the mechanism showing that the anisotropic Qf value was due to anisotropic electron conductivity and anisotropic bonding strength within the superstructure. 相似文献
4.
Sakama Chiaki Inoue Katsumi Sato Taisuke 《Annals of Mathematics and Artificial Intelligence》2021,89(12):1133-1153
Annals of Mathematics and Artificial Intelligence - This paper introduces a novel approach to computing logic programming semantics. First, a propositional Herbrand base is represented in a vector... 相似文献
5.
Nonsalt 1‐(arylmethyloxy)pyrene photoinitiators capable of initiating cationic polymerization 下载免费PDF全文
Analysis of photoproducts derived from 1‐(methoxynaphthalen‐1‐ylmethyloxy)pyrene initiators and polymer end groups demonstrated that methoxynaphthalen‐1‐ylmethyl carbocation is involved in the initiation steps for both styrene (St) and cyclohexene oxide (CHO) polymerization. Charge transfer from the pyrenyloxy oxygen atom to the methoxynaphthalen‐1‐ylmethyl chromophore in the singlet excited state is assumed to be responsible for the efficient generation of the carbocation species, which also initiates the copolymerization of St and CHO. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40510. 相似文献
6.
Rina Sakai Yuji Morikawa Chiaki Kondo Hiroyuki Oka Hirofumi Miyajima Kihei Kubo Takeki Uehara 《International journal of molecular sciences》2014,15(10):17256-17269
In vitro mammalian cytogenetic tests detect chromosomal aberrations and are used for testing the genotoxicity of compounds. This study aimed to identify a supportive genomic biomarker could minimize the risk of misjudgments and aid appropriate decision making in genotoxicity testing. Human lymphoblastoid TK6 cells were treated with each of six DNA damage-inducing genotoxins (clastogens) or two genotoxins that do not cause DNA damage. Cells were exposed to each compound for 4 h, and gene expression was comprehensively examined using Affymetrix U133A microarrays. Toxicogenomic analysis revealed characteristic alterations in the expression of genes included in cyclin-dependent kinase inhibitor 1A (CDKN1A/p21)-centered network. The majority of genes included in this network were upregulated on treatment with DNA damage-inducing clastogens. The network, however, also included kinesin family member 20A (KIF20A) downregulated by treatment with all the DNA damage-inducing clastogens. Downregulation of KIF20A expression was successfully confirmed using additional DNA damage-inducing clastogens. Our analysis also demonstrated that nucleic acid constituents falsely downregulated the expression of KIF20A, possibly via p16 activation, independently of the CDKN1A signaling pathway. Our results indicate the potential of KIF20A as a supportive biomarker for clastogenicity judgment and possible mechanisms involved in KIF20A downregulation in DNA damage and non-DNA damage signaling networks. 相似文献
7.
An ultrasonic treatment system, using a TiO2 photocatalyst, was used to disinfect Legionella pneumophila. A kinetic study of the process indicates that TiO2 significantly improves the disinfection process. The concentrations of viable cells were reduced to 6% of the initial concentrations in the presence of 0.2 g/ml TiO2 after a 30 min of treatment period, while only an 18% reduction was observed in the absence of TiO2. The potency of the disinfection could be enhanced, to some extent, by increasing the amount of TiO2 used. Cell concentrations were decreased by an order of 3 within 30 min of treatment in the presence of 1.0 g/ml TiO2. The disinfection power in the presence of TiO2 versus Al2O3 was also compared and the findings showed that TiO2 induced a higher cell killing. No significant effect of initial cell concentration on the disinfection was found in the range of 102-107 CFU/ml after a 30 min of treatment period. The mechanism of cell killing was investigated by examining the effects of OH radical scavengers such as ascorbic acid, histidine and glutathione. The disinfection power was reduced in samples that contained these radical scavengers, thus indicating the importance of OH radicals. 相似文献
8.
Reed (Phragmites australis), a commonly used macrophyte in the wetlands constructed for water purification, was investigated as a new biosorbent for the removal of Cu(2+), Cd(2+), Ni(2+), Pb(2+) and Zn(2+) from aqueous solution. The metal adsorption capacity of reed biomass was improved significantly by water-wash, base- and acid-treatment. The maximum sorption of NaOH-pretreated reed biomass was observed near neutral pH for Cu(2+), Cd(2+), Ni(2+) and Zn(2+), while that for Pb(2+) was from an acidic range of pH 4.0 or higher. The maximum metal adsorption capacity on a molar basis assumed by Langmuir model was in the order of Cu(2+)>Ni(2+)>Cd(2+)>Zn(2+)>Pb(2+). Reed biosorbent showed a very high adsorption affinity value, which helps predict its high ability to adsorb heavy metals at low concentration. Desorption of heavy metals and regeneration of the biosorbent was attained simultaneously by acid elution. Even after three cycles of adsorption-elution, the adsorption capacity was regained completely and the desorption efficiency of metal was maintained at around 90%. 相似文献
9.
Yoshihito Nakagawa Yukihiro Akao Kohei Taniguchi Akemi Kamatani Tomomitsu Tahara Toshiaki Kamano Naoko Nakano Naruomi Komura Hirokazu Ikuno Takafumi Ohmori Yasutaka Jodai Masahiro Miyata Mistuo Nagasaka Tomoyuki Shibata Naoki Ohmiya Ichiro Hirata 《International journal of molecular sciences》2015,16(1):1526-1543
Accumulating data indicates that certain microRNAs (miRNAs or miRs) are differently expressed in samples of tumors and paired non-tumorous samples taken from the same patients with colorectal tumors. We examined the expression of onco-related miRNAs in 131 sporadic exophytic adenomas or early cancers and in 52 sporadic flat elevated adenomas or early cancers to clarify the relationship between the expression of the miRNAs and the endoscopic morphological appearance of the colorectal tumors. The expression levels of miR-143, -145, and -34a were significantly reduced in most of the exophytic tumors compared with those in the flat elevated ones. In type 2 cancers, the miRNA expression profile was very similar to that of the exophytic tumors. The expression levels of miR-7 and -21 were significantly up-regulated in some flat elevated adenomas compared with those in exophytic adenomas. In contrast, in most of the miR-143 and -145 down-regulated cases of the adenoma-carcinoma sequence and in some of the de novo types of carcinoma, the up-regulation of oncogenic miR-7 and/or -21 contributed to the triggering mechanism leading to the carcinogenetic process. These findings indicated that the expression of onco-related miRNA was associated with the morphological appearance of colorectal tumors. 相似文献
10.