全文获取类型
收费全文 | 1274篇 |
免费 | 15篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 101篇 |
化学工业 | 376篇 |
金属工艺 | 24篇 |
机械仪表 | 31篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 59篇 |
轻工业 | 85篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 80篇 |
一般工业技术 | 293篇 |
冶金工业 | 34篇 |
原子能技术 | 34篇 |
自动化技术 | 144篇 |
出版年
2024年 | 4篇 |
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 23篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 26篇 |
2015年 | 13篇 |
2014年 | 31篇 |
2013年 | 62篇 |
2012年 | 47篇 |
2011年 | 82篇 |
2010年 | 46篇 |
2009年 | 48篇 |
2008年 | 71篇 |
2007年 | 69篇 |
2006年 | 55篇 |
2005年 | 47篇 |
2004年 | 43篇 |
2003年 | 50篇 |
2002年 | 46篇 |
2001年 | 33篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 37篇 |
1997年 | 29篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有1293条查询结果,搜索用时 15 毫秒
1.
Toshimitsu Suzuki Osamu Yamada Yasuhiko Takahashi Yoshihisa Watanabe 《Fuel Processing Technology》1985,10(1):33-43
Hydroliquefaction of low-sulfur Australian coals (Wandoan and Yallourn) was studied using iron carbonyl complexes as catalyst. The addition of Fe(CO)5 (2.8 wt% Fe of coal) increased coal conversion from 48.6 to 85.2% for Wandoan coal, and from 36.7 to 69.7% for Yallourn coal in 1-methylnaphthalene at 425°C under an initial hydrogen pressure of 50 kg cm?2. When molecular sulfur was added to iron carbonyls (Fe(CO)5, Fe2(CO)9 and Fe3(CO)12), higher coal converions ( > 92%) and higher oil yields (>46%) were obtained, along with an increase in the amount of hydrogen transferred to coal from the gas phase (0.2 to 2.8%, d.a.f. coal basis). In the liquefaction studies using a hydrogen donor solvent, tetralin, Fe(CO)5S catalyst increased the amount of hydrogen absorbed from the gaseous phase and decreased the amount of naphthalene dehydrogenated from tetralin. The direct hydrogen transfer reaction from molecular hydrogen to coal fragment radicals seems to be a major reaction pathway. Organic sulfur compounds, dimethyldisulfide and benzothiophene, and inorganic FeS2 and NiS were found to be good sulfur sources to Fe(CO)5. From X-ray diffraction analyses of liquefaction residues, it is concluded that Fe(CO)5 was converted into pyrrhotite (Fe1?xS) when sulfur was present, but into Fe3O4 in the absence of sulfur. 相似文献
2.
The NMR spectra of olefinic protons in the four representative conjugated fatty acid methyl esters, methylcis-9,trans-11-octadecadienoate, methyltrans-9,trans-11-octadecadienoate, methyl α eleostearate, and methyl β eleostearate, were studied. The chemical shift of each olefinic
proton in these compounds was determined by considering their intramolecular environment. Coupling constants were also obtained
as the results of spectral analysis. 相似文献
3.
Hoshino O 《Neural computation》2007,19(2):351-370
Auditory communication signals such as monkey calls are complex FM vocal sounds and in general induce action potentials in different timing in the primary auditory cortex. Delay line scheme is one of the effective ways for detecting such neuronal timing. However, the scheme is not straightforwardly applicable if the time intervals of signals are beyond the latency time of delay lines. In fact, monkey calls are often expressed in longer time intervals (hundreds of milliseconds to seconds) and are beyond the latency times observed in the brain (less than several hundreds of milliseconds). Here, we propose a cochleotopic map similar to that in vision known as a retinotopic map. We show that information about monkey calls could be mapped on a cochleotopic cortical network as spatiotemporal firing patterns of neurons, which can then be decomposed into simple (linearly sweeping) FM components and integrated into unified percepts by higher cortical networks. We suggest that the spatiotemporal conversion of auditory information may be essential for developing the cochleotopic map, which could serve as the foundation for later processing, or monkey call identification by higher cortical areas. 相似文献
4.
Yuta Uenoyama Atsushi Matsuda Kazune Ohashi Koji Ueda Misaki Yokoyama Takuya Kyoutou Kouji Kishi Youichi Takahama Masaaki Nagai Takaaki Ohbayashi Osamu Hotta Hideki Matsuzaki 《International journal of molecular sciences》2022,23(9)
Aberrant glycosylation of IgA1 is involved in the development of IgA nephropathy (IgAN). There are many reports of IgAN markers focusing on the glycoform of IgA1. None have been clinically applied as a routine test. In this study, we established an automated sandwich immunoassay system for detecting aberrant glycosylated IgA1, using Wisteria floribunda agglutinin (WFA) and anti-IgA1 monoclonal antibody. The diagnostic performance as an IgAN marker was evaluated. The usefulness of WFA for immunoassays was investigated by lectin microarray. A reliable standard for quantitative immunoassay measurements was designed by modifying a purified IgA1 substrate. A validation study using multiple serum specimens was performed using the established WFA-antibody sandwich automated immunoassay. Lectin microarray results showed that WFA specifically recognized N-glycans of agglutinated IgA1 in IgAN patients. The constructed IgA1 standard exhibited a wide dynamic range and high reactivity. In the validation study, serum WFA-reactive IgA1 (WFA+-IgA1) differed significantly between healthy control subjects and IgAN patients. The findings indicate that WFA is a suitable lectin that specifically targets abnormal agglutinated IgA1 in serum. We also describe an automated immunoassay system for detecting WFA+-IgA1, focusing on N-glycans. 相似文献
5.
Wataru Tamura Arata Yasuda Ken Suto Masasuke Hosokawa Osamu Itoh Jun-Ichi Nishizawa 《Journal of Electronic Materials》2003,32(10):1079-1084
Effects of Bi doping in PbTe liquid-phase epitaxial layers grown by the temperature difference method under controlled vapor
pressure (TDM-CVP) are investigated. For Bi concentrations in the solution, xBi, lower than 0.2 at.%, an excess deep-donor level (activation energy Ed≈0.03–0.04 eV) appears, and Hall mobility is low. In contrast, for xBi>0.2 at.%, Hall mobility becomes very high, while carrier concentration is in the range of 1017 cm−3. Inductive coupled plasma (ICP) emission analysis shows that, for xBi=1 at.%, Bi concentration in the epitaxial layer is as high as NBi=2.3–2.7 × 1019 cm−3. These results indicate that Bi behaves not only as a donor but also as an acceptor, and the nearest neighbor or very near
donor-acceptor (D-A) pairs are formed, so that strong self-compensation of Bi takes place. Carrier concentration for highly
Bi-doped layers shows a minimum at a Te vapor pressure of 2.2 × 10−5 torr for growth temperature 470°C, which is coincident with that of the undoped PbTe. 相似文献
6.
Jun-ichi Nishizawa Akihiko Murai Hiroki Makabe Osamu Ito Tomoyuki Kimura Ken Suto Yutaka Oyama 《Solid-state electronics》2004,48(12):2251-2254
The tunnel injection transit time (TUNNETT) diodes with p+p+n+n−n+ structure were fabricated by liquid phase epitaxy (LPE). About 100 Å tunnel junction (p+n+) was successfully prepared by the double impurity diffusion of Ge and S during LPE growth. Continuous wave (CW) oscillation was realized at 51.520 GHz in the V-band cavity with the phase noise of −60 dBc/Hz at 1 kHz bandwidth. 相似文献
7.
Maehara Fumiaki Nakamura Osamu Takanashi Hitoshi 《Wireless Personal Communications》2000,15(3):181-197
We propose a novel SIR weighting postdetection combining diversity scheme with a new accurate SIR estimation method. The SIR is estimated and used as the weighting factor to compensate severe cochannel interference, one of the most important issues for PCS in terms of frequency utilization. Theimprovement offered by the proposal depends on SIR estimation accuracy.The SIR is, in this paper, estimated by a matched filter where theauto-correlation between received signal and unique word is calculated. Computer simulationsconfirm that the SIR of each diversity branch can be estimated easily andaccuratelyby the proposed SIR estimation method. The proposed diversity scheme achievesaperformance very close to that of ideal SINR weighting diversity underRayleighfading with severe cochannel interference. When average SIR = 10 dB and thenumber of branches(L)=4, the proposed diversity scheme lowers the requiredEb/N0 by 5 dB at BER = 1×10-3compared to conventional maximal ratio combining diversity. This paper alsopresentsthe unique word length required to realize adequate performance, i.e.,robustnessagainst high-pitch Rayleigh fading. 相似文献
8.
Overview on Technical Issues for Future Mobile Network and a Proposal of DLC Scheme in Wireless Link
This paper gives an overview on technical issues for future mobile networks. the QoS control for multimedia services, security function, expansion of network capacity, expansion of address space, multicast function, radio link quality and mobility control of terminals are taken up as technical issues.Then, a novel DLC scheme in wireless link named EREP-ARQ (Estimation and Report of Error Pattern ARQ) which can reduce the retransmission ratio is proposed. In this scheme, error pattern generated in the radio link is estimated at the receiver side and the estimated error pattern is returned to the transmission side. If the estimation is correct, no retransmission is needed. Compared to conventional SR-ARQ, throughput can be improved by17% and Cell Loss Ratio (or Packet Loss Rate) can be reduced to less than 1/10 by the proposed EREP-ARQ. 相似文献
9.
Chil-Woo Lee Osamu Hasegawa Wiwat Wongwarawipat Hiroshi Dohi Mitsuru Ishizuka 《Journal of Visual Communication and Image Representation》1991,2(4)
This paper describes a system that can synthesize realistic sequential images of moving goldfish based on the image understanding result of real goldfish. To analyze and synthesize images in real-time, we have constructed a hardware system that consists of 32 paralell transputers with a high-speed visual-data interface called VIT (Visual Interface for Transpputer Network). The system is very flexible and powerful for various types of image processing because it can be extended according to the required computational cost. In the understanding process, we assume that the target object, a goldfish in this case, deforms its shape pliably in 3-D space and moves only in a two-dimensional direction. A modeling, called the Bone-Structured Solid Modeler, which is suitable for representing deformable objects such as living things, plays an important role in the understanding and synthesis processes of the deformable object. Three types of constraints for motion, namely, static, dynamic, and object, are utilized to verify the estimated pose and orientation of the object. In the motion synthesis process, realistic moving images are synthesized by controlling the model employing the motion understanding result. Simulation results are presented to show the effectiveness of the system. The technology discussed in this paper is expected to play a key role in the realization of future visual human interfaces. 相似文献
10.
Keiji Sakaki Toshihiro Yokochi Osamu Suzuki Toshikatsu Hakuta 《Journal of the American Oil Chemists' Society》1990,67(9):553-557
The extraction of oil from fungi (Mortierella ramanniana var.angulispora) was studied using carbon dioxide (CO2), nitrous oxide (N2O), trifluoromethane (CHF3) and sulfur hexafluoride (SF6) under supercritical conditions. The oil solubility was highest in SC-N2O followed by SC-CO2, while both SC-CHF3 and SC-SF6 showed poorer solvent power. The recorded oil solubilities at 333 K and 24.5 MPa were 2.3 wt% in N2O, 0.48 wt% in CO2, 0.0099 wt% in CHF3 and 0.0012 wt% in SF6.
The oil solubilities in SC-N2O and SC-CO2 were measured over the pressure range 15.7–29.4 MPa and at temperatures ranging from 313–353 K. N2O always showed greater solvent power than did CO2 at the same temperature and pressure. The solvent power of a supercritical fluid increases with density at a given temperature,
and increases with temperature at constant density.
The change in neutral lipid composition of the extracted oil with the extraction ratio was measured. Free fatty acids or diglycerides
were extracted more easily than triglycerides or sterol esters. The change in fatty acid composition was also measured. The
proportion of γ-linolenic acid in the extract remained constant throughout the extraction. 相似文献