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排序方式: 共有469条查询结果,搜索用时 62 毫秒
31.
Joshua D. Caldwell Kendrick X. Liu Marko J. Tadjer Orest J. Glembocki Robert E. Stahlbush Karl D. Hobart Fritz Kub 《Journal of Electronic Materials》2007,36(4):318-323
Stacking faults within 4H-SiC PiN diodes are known to be detrimental to device operation. Here, we present electroluminescence
(EL) images of 4H-SiC PiN diodes providing evidence that electrically and optically stimulated Shockley stacking fault (SSF)
propagation is a reversible process at temperatures as low as 210°C. Optical beam induced current (OBIC) images taken following
complete optical stressing of a PiN diode and that lead to a small number of completely propagated SSFs provide evidence that
such defects propagate across the n–/p+ interface and continue to grow throughout the p+ layer. These observations bring about
questions regarding the validity of the currently accepted driving force mechanism for SSF propagation. 相似文献
32.
B. Vanderborght A. Albu-Schaeffer A. Bicchi E. Burdet D.G. Caldwell R. Carloni M. Catalano O. Eiberger W. Friedl G. Ganesh M. Garabini M. Grebenstein G. Grioli S. Haddadin H. Hoppner A. Jafari M. Laffranchi D. Lefeber S. Wolf 《Robotics and Autonomous Systems》2013,61(12):1601-1614
Variable Impedance Actuators (VIA) have received increasing attention in recent years as many novel applications involving interactions with an unknown and dynamic environment including humans require actuators with dynamics that are not well-achieved by classical stiff actuators. This paper presents an overview of the different VIAs developed and proposes a classification based on the principles through which the variable stiffness and damping are achieved. The main classes are active impedance by control, inherent compliance and damping actuators, inertial actuators, and combinations of them, which are then further divided into subclasses. This classification allows for designers of new devices to orientate and take inspiration and users of VIA’s to be guided in the design and implementation process for their targeted application. 相似文献
33.
J. D. Caldwell B. S. Cooke M. K. Greer 《Journal of the American Oil Chemists' Society》2011,88(11):1669-1674
Analysis of used frying oil samples by high performance liquid chromatography–size exclusion chromatography (HPLC–SEC or HPSEC)
was compared to AOCS Official Method Cd 20-91 (silica gel column chromatography) for the purpose of developing a rapid analysis
of total polar compounds (TPC). In a direct comparison of the two analytical methods using four different sets of used frying
oils (21 total oil samples) ranging from fresh to discard quality (4.3 to 35.4% TPC by column chromatography), the weight
percent total polar compounds (%TPC) determined by HPLC–SEC averaged 0.71% higher than the values by silica gel column chromatography.
Reproducibility of the HPLC–SEC method of s
r = 0.30 and RSDr% = 1.22 compares to the variability of s
r = 0.29 and RSDr = 1.3 for samples of approximately the same %TPC, reported in AOCS Method Cd 20-91. Because the rapid method does not separate
pure (non-polar) triacylglycerol (TAG) and polar, oxidized TAG (OX-TAG), a high concentration of OX-TAG will quantitatively
affect the results. This places practical limits on the types of studies to which the method may be applied if a separate
analysis for the OX-TAG is not performed. Advantages of the HPLC–SEC method include the following. It uses about 75% less
solvent than standard column chromatography methods for determination of %TPC. This HPLC–SEC method is very similar to AOCS
Official Method Cd 22-91, and thus, also separates and quantifies polymerized triacylglycerols. The HPLC–SEC method determines
both TAG polymer concentration and %TPC of used frying oils in about 1 h. 相似文献
34.
35.
Eberhard W. Neuse Maria G. Meirim David D. NDa Gregg Caldwell 《Journal of Inorganic and Organometallic Polymers》1999,9(4):221-230
Ferrocene, the parent of the metallocene family of organotransition metal compounds, has come to occupy a significant niche in cancer research. Developmental work in the authors' laboratory has been focused on the synthesis of antiproliferative ferrocene conjugates in which the bioactive ferrocene unit is covalently, yet bioreversibly bound (anchored) to water-soluble carrier polymers designed in accordance with requisite biomedical specifications. The anchoring link in most of these conjugates has been an aliphatic spacer containing the biofissionable amide group. In this communication the synthesis of a class of ferrocene conjugates is reported in which the ferrocene group is carrier-anchored through spacers containing an ester link, of interest here because of potentially different drug release behavior. The carriers are polyamides equipped with variously spaced hydroxyl side groups, to which the ferrocenylation agent, 4-ferrocenylbutanoic acid, is connected through esterification. The coupling reactions, mediated by carbodiimide agent and catalyzed by 4-(dimethylamino)pyridine, are carried out in DMF at temperatures not exceeding 65°C, and the water-soluble product polymers are isolated in yields of typically 70–85% by precipitation, aqueous dialysis, and freeze-drying. With the molar feed ratios chosen in these coupling experiments, the incorporation of ferrocene, assessed by 1H NMR spectroscopy, corresponds to iron contents of roughly 2.5–5.5%, by mass. The conjugates will be included in a forthcoming bioactivity screening program. 相似文献
36.
E. P. Gorzkowski S. B. Qadri B. B. Rath R. Goswami J. D. Caldwell 《Journal of Electronic Materials》2013,42(5):799-804
We have demonstrated that large quantities of β-SiC nanostructures can be obtained from rice husk agricultural waste by using controlled conditions in a thermogravimetric setup. This simple and inexpensive method of producing these structures on a large scale is critical for applications in nanoelectronics, nanosensors, and biotechnology. The temperature and atmosphere are two critical elements in forming either α-cristobalite (SiO2) or β-SiC. Using different characterization methods (x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy), we have shown that pyrolysis of rice husks in argon atmosphere at 1375°C results in simultaneous formation of carbon nanotubes, β-SiC nanowires/nanorods, and β-SiC powder. 相似文献
37.
38.
Dr. Shinpei Uno Dr. Alexander H. Harkiss Dr. Roy Chowdhury Dr. Stuart T. Caldwell Tracy A. Prime Dr. Andrew M. James Dr. Brendan Gallagher Dr. Julien Prudent Prof. Dr. Richard C. Hartley Prof. Dr. Michael P. Murphy 《Chembiochem : a European journal of chemical biology》2023,24(11):e202200774
The targeting of bioactive molecules and probes to mitochondria can be achieved by coupling to the lipophilic triphenyl phosphonium (TPP) cation, which accumulates several hundred-fold within mitochondria in response to the mitochondrial membrane potential (Δψm). Typically, a simple alkane links the TPP to its “cargo”, increasing overall hydrophobicity. As it would be beneficial to enhance the water solubility of mitochondria-targeted compounds we explored the effects of replacing the alkyl linker with a polyethylene glycol (PEG). We found that the use of PEG led to compounds that were readily taken up by isolated mitochondria and by mitochondria inside cells. Within mitochondria the PEG linker greatly decreased adsorption of the TPP constructs to the matrix-facing face of the mitochondrial inner membrane. These findings will allow the distribution of mitochondria-targeted TPP compounds within mitochondria to be fine-tuned. 相似文献
39.
40.
Eberhard W. Neuse Gregg Caldwell 《Journal of Inorganic and Organometallic Polymers》1997,7(3):163-181
As a follow-up study to previous work involving the platination of polyamide carriers through metal chelation by side group-incorporated ethylenediamine ligands, the present investigation is concerned with the synthesis of platinum-containing polymers in which the metal-coordinating ethylenediamine segments are components of the main chain. Two chloro groups in cis geometry are attached to each Pt atom as additional ligands, complementing a square-planar cis-diaminedichloroplatinum(II) complex system. The water-soluble polymeric carriers are synthesized by Michael-type addition polymerization, interfacial polymerization, and high-temperature solution polycondensation techniques and are crudely fractionated by stepwise aqueous dialysis, ultimately in tubing with a molecular mass cutoff of 25,000. Carrier platination is brought about by treatment with tetrachloroplatinate(II) anion in aqueous solution, care being taken to exercise strict control of reaction variables and workup conditions in an effort to restrict platination to the given ligands and avoid metal aquation or hydroxylation. The platinum conjugates, with Pt contents ranging from about 11 to 23% by mass, are completely soluble in aqueous media when freshly prepared, although long-term storage at room temperature in the solid state is conducive to gradual loss of solubility. The conjugates are of interest as carcinostatic agents. 相似文献