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41.
Yusaku Takita Kimiaki Inokuchi Osamu Kobayashi Fumiaki Hori Noboru Yamazoe Tetsuro Seiyama 《Journal of Catalysis》1984,90(2):232-240
The gas-phase oxidation of methyl ethyl ketone was studied on metal oxide catalysts in the presence of water vapor. Two types of competitive partial oxidations, i.e., biacetyl formation and oxidative scission reaction leading to acetaldehyde and acetic acid, took place on every oxide studied at 400–500 K. An approximate linear relationship was observed between the selectivity of each reaction and the acid-base property of the oxides; the former reaction was accelerated on the basic oxides such as Co3O4, while the latter reaction became predominant on the acidic oxides. As Co3O4 was the most effective biacetyl former of single-component oxides, modification of Co3O4 was examined to develop more effective catalysts for biacetyl synthesis. Scission reaction took the place of biacetyl formation over a catalyst where Co2+ ions were located in Y zeolite by an ion-exchanged method. Scission reaction was suppressed when Co oxide was supported on basic oxides such as MgO or CaO; however, the selectivity to biacetyl was slightly decreased due to the occurrence of a new reaction, acetone formation. The addition of Na2O or Li2O to Co3O4 was found to improve the selectivity to biacetyl without loss of catalytic activity. The maximum efficiency (13%) in biacetyl formation was attained at a Li content of ca. 7 at.%. 相似文献
42.
The dose-frequency relationship for each of 2 types of lethal mutations, fractional- and whole-lethal, was obtained using X-rays on Drosophila melanogaster. The results show that fractional-lethal mutations are induced by X-rays, and also that the proportion of fractional-lethal mutations in the total of mutations tends to decrease with increasing doses, namely, 61% at o R, 47% at 500 R, 37% at 1000 R and 20% at 2000 R. The same tendency is observed with visible mutations. In order to consider the problems related to the above results, the relationship between the true frequency and the observed frequency of the induced lethal mutations is discussed, taking into consideration the existence of the ostensible whole-lethal and the ostensible normal. 相似文献
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44.
Chiodarelli N Masahito S Kashiwagi Y Li Y Arstila K Richard O Cott DJ Heyns M De Gendt S Groeseneken G Vereecken PM 《Nanotechnology》2011,22(8):085302
Carbon nanotubes (CNT) are known to be materials with potential for manufacturing sub-20 nm high aspect ratio vertical interconnects in future microchips. In order to be successful with respect to contending against established tungsten or copper based interconnects, though, CNT must fulfil their promise of also providing low electrical resistance in integrated structures using scalable integration processes fully compatible with silicon technology. Hence, carefully engineered growth and integration solutions are required before we can fully exploit their potentialities. This work tackles the problem of optimizing a CNT integration process from the electrical perspective. The technique of measuring the CNT resistance as a function of the CNT length is here extended to CNT integrated in vertical contacts. This allows extracting the linear resistivity and the contact resistance of the CNT, two parameters to our knowledge never reported separately for vertical CNT contacts and which are of utmost importance, as they respectively measure the quality of the CNT and that of their metal contacts. The technique proposed allows electrically distinguishing the impact of each processing step individually on the CNT resistivity and the CNT contact resistance. Hence it constitutes a powerful technique for optimizing the process and developing CNT contacts of superior quality. This can be of relevant technological importance not only for interconnects but also for all those applications that rely on the electrical properties of CNT grown with a catalytic chemical vapor deposition method at low temperature. 相似文献
45.
Ryoichi Monzen Takasumi Hosoda Yusaku Takagawa Chihiro Watanabe 《Journal of Materials Science》2011,46(12):4284-4289
The effects of addition of 0.01 and 0.03 wt% Mg on the bend formability and strength of a Cu–1.8 wt% Be–0.21 wt% Co alloy
aged at 320 °C for 30 min have been investigated metallographically. The addition of Mg to the Cu–Be–Co alloy enhances the
bend formability and strength of the alloy. The enhancement of strength is caused by the increase in volume fraction of
g\textI¢ \gamma_{\text{I}}^{\prime } precipitates in the Cu matrix. In bending of the alloys with and without 0.01 and 0.03 wt% Mg, a number of micro necks first
arise along grain boundaries, and part of them grows, resulting in surface wrinkles, which finally lead to surface cracking.
The cracking is initiated from voids formed by destruction of bar-like γ precipitates in discontinuous precipitation (DP)
cells and propagates along grain boundaries. The addition of Mg decreases the width of DP cells, resulting in better bend
formability. This arises because smaller stress concentration due to less inhomogeneous deformation develops in cells and,
as a result, destruction of the γ precipitates in cells occurs less easily as the cell width decreases. 相似文献
46.
Observation of sperm development and determination of their morphological characteristics are very important to the understanding of phylogenetic relationships and the study of sperm function during fertilization. Although ultrastructural studies of sperm development in the testes of the fruit fly Drosophila have been performed, there are few reports describing electron microscopic morphology of mature sperm, that is, those released from the testes to the seminal vesicles. Here, we present the first report of the sagittal organization of Drosophila sperm head and neck regions by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The head and tail structures of a mature sperm, for example, the acrosome, nucleus, and flagellum, were easy to distinguish by the morphological characteristics of the sperm surface by SEM. The morphological relationships between the surface and internal structures of mature sperm were confirmed by observing longitudinal sections with TEM. Our approach overcame the technical difficulties involved in sample preparation for electron microscopic observation of the Drosophila mature sperm head, and therefore, this study serves as an important foundation for future genetic dissection of sperm ultrastructure and function in male sterile mutants. Microsc. Res. Tech. 77:661–666, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
47.
Kondoh Takashi; Nishijo Hisao; Takamura Yusaku; Kawanishi Chiemi; Torii Kunio 《Canadian Metallurgical Quarterly》1996,110(5):1187
It has been reported that specific alteration of rhythm of environmental temperature (SART) stress induces various physiological changes. In this study, changes in taste preference during SART stress were investigated in rats. Rats were given free access to six amino acid solutions, saline, and water in a choice paradigm. During SART stress, daily food intake increased significantly by 50% whereas the rate of body weight gain decreased significantly to one third that observed during the prestress baseline period. In addition, consumption of histidine solution increased significantly, whereas intakes of water, monosodium glutamate, saline, glycine, arginine, lysine, and threonine were unaffected. Results suggest that a specific preference for histidine emerges during SART stress, which may be related to the stress-induced changes in the histamine turnover in the brain and peripheral tissues. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
48.
Numerical simulations have been performed to predict pressure transients in deep geothermal reservoirs at sub- and super-critical temperatures. First, pressure drawdown and buildup tests of reservoirs with different initial conditions were simulated. The calculated pressure responses are dominated by non-linear changes of fluid kinematic viscosity and compressibility. The pressure of a super-critical zone is shown to cause complex behavior. Short- and long-term production tests in both unbounded and bounded reservoirs were then simulated. Unbounded and bounded reservoirs exhibit very similar short-term production behavior near or above the critical temperature (375–400°C). Unbounded reservoirs of low transmissivity (kh = 1 darcy-meter) exhibit long-term production behavior that depends on whether the reservoir is sub-critical (300–375°C) or super-critical (400°C); substantial increases in flowing enthalpy and declines in feedpoint pressure occur at early times in the super-critical reservoir. 相似文献
49.
50.
In recent servomotor control systems using highspeed microprocessors, it is difficult to obtain accurate speed information by using a low-resolution shaft encoder because encoder pulses are very sparse in the low-speed range. To overcome this problem, the instantaneous speed observer is proposed, system stability is improved, and strong disturbance rejection control is realized. However, when the inertia moment changes, the estimated instantaneous speed has error because the observer uses the nominal value of the inertia moment to calculate the instantaneous speed. For this reason, the identification method of the inertia moment for the “position input-type” speed observer is proposed but it operated at about 50 rpm speed command. This paper proposes some novel identification methods for the “average speed-input type” instantaneous speed observer and identifies the inertia moment in the very low speed range below 1 rpm. 相似文献