全文获取类型
收费全文 | 583篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 59篇 |
综合类 | 3篇 |
化学工业 | 193篇 |
金属工艺 | 10篇 |
机械仪表 | 12篇 |
建筑科学 | 29篇 |
能源动力 | 20篇 |
轻工业 | 58篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 33篇 |
一般工业技术 | 92篇 |
冶金工业 | 25篇 |
原子能技术 | 9篇 |
自动化技术 | 60篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 13篇 |
2015年 | 18篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 18篇 |
2011年 | 37篇 |
2010年 | 33篇 |
2009年 | 32篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 21篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1970年 | 1篇 |
1968年 | 2篇 |
排序方式: 共有607条查询结果,搜索用时 0 毫秒
1.
High performance liquid chromatographic separation of a series of mono-, di- and trihydroxylated 5β-cholanic acids which differ
only in position and configuration of hydroxyl groups at positions C-3, C-7 and/or C-12, is reported. The C-24 free acids
were derivatized to four different classes of UV-sensitive esters, i.e.,p-bromophenacyl (BP),m-methoxyphenacyl (MP), 4-nitrophthalimidemethyl (NPM) and 9-anthrylmethyl (AM) esters, and chromatographed on two, variants
of C18 reversed-phase columns (Nova-Pak C18 and Zorbax ODS) with methanol-water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs
were influenced by both the structure of the C-24 ester groups and the nature of the columns used. Excellent chromatographic
properties were found for those derivatives, particularly for the NPM esters. 相似文献
2.
3.
Pouria Pirzadeh Junichi Tatemura Oliver Po Hakan Hac?gümü? 《Journal of Grid Computing》2012,10(1):109-132
Recently there has been a considerable increase in the number of different Key-Value stores, for supporting data storage and
applications on the cloud environment. While all these solutions try to offer highly available and scalable services on the
cloud, they are significantly different with each other in terms of the architecture and types of the applications, they try
to support. Considering three widely-used such systems: Cassandra, HBase and Voldemort; in this paper we compare them in terms
of their support for different types of query workloads. We are mainly focused on the range queries. Unlike HBase and Cassandra
that have built-in support for range queries, Voldemort does not support this type of queries via its available API. For this
matter, practical techniques are presented on top of Voldemort to support range queries. Our performance evaluation is based
on mixed query workloads, in the sense that they contain a combination of short and long range queries, beside other types
of typical queries on key-value stores such as lookup and update. We show that there are trade-offs in the performance of
the selected system and scheme, and the types of the query workloads that can be processed efficiently. 相似文献
4.
The authors have developed a new type of motor consisting of a piezoelectric device and strain wave gearing, and is called a piezoelectric motor. This is a first step in realizing a low-speed, small-size and lightweight motor. The principle of the motor is that the traveling wave is produced by piezoelectric devices and displacement conversion devices without mechanical resonance, and the torque to rotate the motor is generated by a mechanism of strain wave gearing (circular spline and flexspline) without using friction. The motor is operated at variable frequency and its rotational position (angle) is controlled in open-loop because it is basically a synchronous motor. In this paper, the structure and principle of the proposed motor are explained and the driving method and the mechanical characteristics of an experimental motor also are described. The results are as follows:
- 1 The realizability of the proposed piezoelectric motor is verified experimentally. The experimental motor operates at 2920 steps per revolution, and its speed range is 0 to 960 pps [or 0 to 20 (rpms)].
- 2 The torque characteristics are clarified qualitatively.
- 3 The generated torque of the experimental motor is small (less than 0.03 Nm) and therefore the improvement of the torque is an important subject hereafter.
- 4 It is possible to construct the motor with nonmetallic material. This fact is considered to facilitate obtaining a means to lighten the weight of the motor in the future.
5.
Masashi Ishikawa Masae Iwasaki Hailin Zhao Junichi Saito Cong Hu Qizhe Sun Atsuhiro Sakamoto Daqing Ma 《International journal of molecular sciences》2021,22(9)
Inhalational anesthetics was previously reported to suppress glioma cell malignancy but underlying mechanisms remain unclear. The present study aims to investigate the effects of sevoflurane and desflurane on glioma cell malignancy changes via microRNA (miRNA) modulation. The cultured H4 cells were exposed to 3.6% sevoflurane or 10.3% desflurane for 2 h. The miR-138, -210 and -335 expression were determined with qRT-PCR. Cell proliferation and migration were assessed with wound healing assay, Ki67 staining and cell count kit 8 (CCK8) assay with/without miR-138/-210/-335 inhibitor transfections. The miRNA downstream proteins, hypoxia inducible factor-1α (HIF-1α) and matrix metalloproteinase 9 (MMP9), were also determined with immunofluorescent staining. Sevoflurane and desflurane exposure to glioma cells inhibited their proliferation and migration. Sevoflurane exposure increased miR-210 expression whereas desflurane exposure upregulated both miR-138 and miR-335 expressions. The administration of inhibitor of miR-138, -210 or -335 inhibited the suppressing effects of sevoflurane or desflurane on cell proliferation and migration, in line with the HIF-1α and MMP9 expression changes. These data indicated that inhalational anesthetics, sevoflurane and desflurane, inhibited glioma cell malignancy via miRNAs upregulation and their downstream effectors, HIF-1α and MMP9, downregulation. The implication of the current study warrants further study. 相似文献
6.
Reaction rates in the Mg2Ni---H2 system are still unclear, although they are needed for the process/optimization of hydrogen storage reactors. In this article, the rates of hydrogen absorption and desorption of the magnesium nickel alloy were investigated at different pressures up to 2.0 MPa using a constant-temperature thermogravimetric method. The powder of the alloy was microencapsulated with copper to improve the alloy properties (such as cycling strength) as a pretreatment. In the experiments, weight changes of the smallest amount possible of samples were monitored with the help of an ultra-accurate thermobalance, in order to avoid changes of the sample temperature due to the heat of the reaction. The reaction curves obtained revealed unique dependence of temperature and pressure and influence of thermal hysterisis. It is also possible that hydrogen-absorption and-desorption rates of this hydrogen storage alloy are expressed by the rate equation of first-order reversible reaction. 相似文献
7.
Hirosuke Oku Jyutaro Shudo Kunio Mimura Akinori Haratake Junichi Nagata Isao Chinen 《Lipids》1995,30(2):169-172
A neutral lipid class was isolated by thin-layer chromatography from the skin surface lipids of the hairless mouse. The fraction
migrated faster than triglycerides and had a migration rate similar to that of diacyl alkanediols (diester wax). Upon deacylation,
however, the long-chain diols were identified as 1-alkylglycerol ethers based on their chromatographic properties and on the
mass spectra of their nicotinylidene derivatives. Thus, the skin lipid fraction was identified as 1-O-alkyl-diacylglycerol. The alkyl moieties were all saturated and even-numbered and ranged in chainlength from C16 to C22 with 1-O-hexadecylglycerol amounting to 34% of the total glycerol ether moieties. The fatty acids derived from this lipid fraction
were mostly monoenoic with chainlengths ranging from C16 to C24. The major acyl component was eicosenoic acid (20∶1) representing 61% of the total fatty acids. 相似文献
8.
Takatoshi Tsujimura Junichi Fukawa Kiyoshi Endoh Yuuji Suzuki Kazuhiko Hirabayashi Takahiro Mori 《Journal of the Society for Information Display》2014,22(8):412-418
To come out with a successful organic light‐emitting diode (OLED) lighting business, it is very important to have clear differentiation of OLED from LEDs. Flexible OLED has merits, such as capability to be mounted on the curved wall, which is not easy for LEDs to achieve the feature. There are several approaches to make flexible OLEDs especially among those plastic barrier films that can bring high level of flexibility, which could not be achieved by any conventional lighting method. In this paper, barrier films with various water vapor transmission rate values, including 10? 6 order, are applied, and the conditions to have almost no dark spot growth under 85 °C and 85% high temperature/humidity test are shown. Flexible OLED panels are manufactured with the world's first roll‐to‐roll equipment using plastic barrier film. 相似文献
9.
Lida T Nakamori R Yabuta R Yada S Takagi Y Mano N Ikegawa S Goto J Nambara T 《Lipids》2002,37(1):101-110
A facile and efficient synthesis of the carboxyl-linked glucosides of bile acids is described. Direct esterification of unprotected
bile acids with 2,3,4,6-tetra-O-benzyl-d-glucopyranose in pyridine in the presence of 2-chloro-1,3,5-trinitrobenzene as a coupling agent afforded a mixture of the
α- and β-anomers (ca. 1∶3) of the 1-O-acyl-d-glucoside benzyl ethers of bile acids, which was separated effectively on a C18 reversedphase chromatography column (isolated yields of α- and β-anomers are 4–9% and 12–19%, respectively). Subsequent hydrogenolysis
of the α- and β-acyl glucoside benzyl ethers on a 10% Pd−C catalyst in acetic acid/methanol/EtOAc (1∶2∶2, by vol) at 35°C
under atmospheric pressure gave the corresponding free esters in good yields (79–89%). Chemical specificities such as facile
hydrolysis and transesterification of the acyl glucosides in various solvents were also discussed. 相似文献
10.
Jiangyan Zhang Tielong Shen Junichi Kako Shozo Yoshida 《International Journal of Control, Automation and Systems》2009,7(4):659-667
In this paper, the speed control problem of internal combustion engines is investigated based on mean-value engine models.
The dynamics of internal combustion engines is a complicated nonlinear system, and usually, it is difficult to know the exact
values of the physical parameters. First, a Lyapunov-based design method is shown without requiring the full information of
the physical parameters. Then, to improve transient performance, the design method is extended to several cases under different
operation conditions. Numerical simulation results are presented for comparing the proposed design methods. Finally, experiments
are conducted on an engine test bench and the results demonstrate the validity of the proposed design methods.
Recommended by Editorial Board member Myotaeg Lim under the direction of Editor Hyun Seok Yang. The authors are grateful to
Kai Zheng for his assistance of the model identification experiments.
Jiangyan Zhang received the B.E. and M.E. degrees in Electrical Engineering, Yanshan University, China, in 2005 and 2008, respectively.
Now, she is a Ph.D. candidate with the Department of Engineering and Applied Sciences, Sophia University, Tokyo, Japan. Her
current research interests include nonlinear system control theory and applications to powertrain system control.
Tielong Shen received the Ph.D. degree in Mechanical Engineering from Sophia University, Tokyo, Japan, March, 1992. From April 1992, he
has been a faculty member of the Chair of Control Engineering in Department of Mechanical Engineering, Sophia University,
where he currently serves as professor of the Department of Engineering and Applied Science. His research interests include
control theory and application in mechanical systems, power systems, and automotive powertrain. Currently, he is an Associate
Editor for the IEEE Control System Society Conference Editorial Board, and is serving as Associate Editor of Journal of Control
Theory and Applications, and the Regional Editor Asia-Pacific for International Journal of Modeling, Identification and Control
etc.
Junichi Kako received the B.E. degree from Nagoya Institute of Technology, Nagoya, Japan. He joined Toyota Motor Corporation, Tokyo, Japan
in 1989. He worked on various aspects of automotive powertrain control. From 1989 to 1994, he took part in the team for the
development of Laboratory Automation (LA) system, Engineering Office Automation (EOD) system, and embedded system of powertrain
control. During 1995–2001, he focused on the engine control systems in Powertrain Management Engineering Division. In 2002,
he was with Future Project Division in which he was responsible for the R&D of model-based engine control system. Currently,
he is developing engine control systems in the Powertrain Management Engineering Division, Toyota Motor Corporation.
Shozo Yoshida received the M.S. degree in Engineering from Kyoto University, Kyoto, Japan. He joined Toyota Motor Corporation, Tokyo, Japan
in 2000. From 2000 to 2004, he was with Future Project Division and worked on physical combustion modeling for Model-based
Control Development. Since 2005, he has been with the Powertrain Management Engineering Division Toyota Motor Corporation,
and is a member of the R&D of Model-based Engine Calibration. 相似文献