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排序方式: 共有151条查询结果,搜索用时 10 毫秒
61.
Sajal Maity Madhuri Hande Tuomas Lönnberg 《Chembiochem : a European journal of chemical biology》2020,21(16):2321-2328
Oligonucleotides incorporating a central C-nucleoside with either a rigid or flexible benzaldoxime base moiety have been synthesized, and the hybridization properties of their metallacyclic derivatives have been studied by UV melting experiments. In all cases, the metallated duplexes were less stable than their unmetallated counterparts, and the metallacyclic nucleobases did not show a clear preference for any of the canonical nucleobases as a base-pairing partner. With palladated oligonucleotides, increased flexibility translated to less severe destabilization, whereas the opposite was true for the mercurated oligonucleotides; this reflects the greater difficulties in accommodating a rigid PdII-mediated base pair than a rigid HgII-mediated base pair within the base stack of a double helix. 相似文献
62.
Prolonged Dye Release from Mesoporous Silica‐Based Imaging Probes Facilitates Long‐Term Optical Tracking of Cell Populations In Vivo 下载免费PDF全文
Jessica M. Rosenholm Tina Gulin‐Sarfraz Veronika Mamaeva Rasmus Niemi Ezgi Özliseli Diti Desai Daniel Antfolk Eva von Haartman Desiré Lindberg Neeraj Prabhakar Tuomas Näreoja Cecilia Sahlgren 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(12):1578-1592
Nanomedicine is gaining ground worldwide in therapy and diagnostics. Novel nanoscopic imaging probes serve as imaging tools for studying dynamic biological processes in vitro and in vivo. To allow detectability in the physiological environment, the nanostructure‐based probes need to be either inherently detectable by biomedical imaging techniques, or serve as carriers for existing imaging agents. In this study, the potential of mesoporous silica nanoparticles carrying commercially available fluorochromes as self‐regenerating cell labels for long‐term cellular tracking is investigated. The particle surface is organically modified for enhanced cellular uptake, the fluorescence intensity of labeled cells is followed over time both in vitro and in vivo. The particles are not exocytosed and particles which escaped cells due to cell injury or death are degraded and no labeling of nontargeted cell populations are observed. The labeling efficiency is significantly improved as compared to that of quantum dots of similar emission wavelength. Labeled human breast cancer cells are xenotransplanted in nude mice, and the fluorescent cells can be detected in vivo for a period of 1 month. Moreover, ex vivo analysis reveals fluorescently labeled metastatic colonies in lymph node and rib, highlighting the capability of the developed probes for tracking of metastasis. 相似文献
63.
Ayaka Kamada Aviad Levin Zenon Toprakcioglu Yi Shen Viviane Lutz‐Bueno Kevin N. Baumann Pezhman Mohammadi Markus B. Linder Raffaele Mezzenga Tuomas P. J. Knowles 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(9)
Protein‐based fibers are used by nature as high‐performance materials in a wide range of applications, including providing structural support, creating thermal insulation, and generating underwater adhesives. Such fibers are commonly generated through a hierarchical self‐assembly process, where the molecular building blocks are geometrically confined and aligned along the fiber axis to provide a high level of structural robustness. Here, this approach is mimicked by using a microfluidic spinning method to enable precise control over multiscale order during the assembly process of nanoscale protein nanofibrils into micro‐ and macroscale fibers. By varying the flow rates on chip, the degree of nanofibril alignment can be tuned, leading to an orientation index comparable to that of native silk. It is found that the Young's modulus of the resulting fibers increases with an increasing level of nanoscale alignment of the building blocks, suggesting that the mechanical properties of macroscopic fibers can be controlled through varying the level of ordering of the nanoscale building blocks. Capitalizing on strategies evolved by nature, the fabrication method allows for the controlled formation of macroscopic fibers and offers the potential to be applied for the generation of further novel bioinspired materials. 相似文献
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65.
Crosslinkable poly(lactic acid)‐based materials: Biomass‐derived solution for barrier coatings 下载免费PDF全文
The demand for biobased barrier packaging alternatives is constantly growing. Poly(lactic acid) (PLA)‐based polymers are one of the most extensively studied biomass‐derived synthetic polymers; however, they typically lack water‐barrier properties. We synthesized a copolymer of d ,l ‐lactic acid, 1,4‐butanediol, and itaconic acid [poly(d ,l ‐lactic acid–1,4‐butanediol–itaconic acid) (PLABDIA)] via bulk polycondensation. The radical crosslinking reactions of the synthesized polymer were investigated with bulk crosslinking trials to find a formulation that was suitable for a rapidly crosslinkable barrier coating. The crosslinking efficiency was tested with methacrylate and acrylate crosslinkers together with peroxide radical initiators. Poly(ethylene glycol) diacrylate (number‐average molecular weight = 250 g/mol) together with dilauroyl peroxide proved to be the best crosslinker–initiator combination. An aqueous dispersion of PLABDIA was prepared with a thermomechanical method and applied to commercial boxboard on a pilot‐scale line coater. With a coating weight of 10 g/m2, a water vapor transmission rate of 22.8 g/m2d was achieved, and this coating outperformed commercial extruded PLA coatings. The samples also showed very good grease resistance and would, therefore, be a good solution for the packaging of dry and fatty goods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44326. 相似文献
66.
Lukas C. Gerber Dirk Mohn Giuseppino Fortunato Monika Astasov‐Frauenhoffer Thomas Imfeld Tuomas Waltimo Matthias Zehnder Wendelin J. Stark 《Polymer Engineering and Science》2011,51(1):71-77
Polymer fibers are used for a wide range of materials in contact with the human body. Since bacterial contamination may cause diseases, it is desirable to provide fibers with antimicrobial properties. This work investigates the ability of silver‐tricalcium phosphate nanoparticles (Ag/TCP) to build a reactive system when incorporated in polyamide fibers. In the presence of bacteria, the TCP carrier particles are biodegraded and trigger the release of silver. For this work, Ag/TCP nanoparticles (1.3 wt% silver) were produced by flame spray synthesis and subsequently processed with polyamide 6 to fibers (125‐μm thick, containing 260 ppm silver) with the aid of extrusion and melt‐spinning for subsequent antibacterial testing. The fibers were contaminated with the clinically relevant strains Escherichia coli or Streptococcus sanguinis, respectively. The reactive fibers demonstrated significantly reduced plate count within 24 h (the number of colony forming units was reduced by 99.999% with E. coli and 99.6% with S. sanguinis compared with pure PA6 reference fibers). These reactive properties of easily integrated antibacterial silver suggest an implementation of intelligent fibers to a wide range of applications. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers 相似文献
67.
Pressure drop evolution during filtration of bimodal aerosol was studied experimentally. A low-pressure drop pre-filter upstream of the actual collection filter was demonstrated to significantly reduce the pressure drop growth rate, when the aerosol is dominated by coarse particles. The pressure drop evolution during depth-filtration, that took place mainly in a pre-filter, could be predicted by adding up the separately measured contributions from the unimodal fine and coarse aerosols. However, the cake filtration (pre-filter was not used) of coarse particles alone resulted in a faster clogging rate as compared to the same amount of coarse particles accompanied with fine particles (mass ratio coarse:fine 3:1). Apparently, fine particles deposited on coarse particles affect their surface properties and thus the porosity of the cake formed. 相似文献
68.
Hongjia Zhu Masako Narita Jerelle A. Joseph Georg Krainer William E. Arter Ioana Olan Kadi L. Saar Niklas Ermann Jorge R. Espinosa Yi Shen Masami Ando Kuri Runzhang Qi Timothy J. Welsh Rosana Collepardo-Guevara Masashi Narita Tuomas P. J. Knowles 《Chembiochem : a European journal of chemical biology》2023,24(1):e202200450
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70.
When donating money to a (say, charitable) cause, it is possible to use the contemplated donation as a bargaining chip to induce other parties interested in the charity to donate more. Such negotiation is usually done in terms of matching offers, where one party promises to pay a certain amount if others pay a certain amount. However, in their current form, matching offers allow for only limited negotiation. For one, it is not immediately clear how multiple parties can make matching offers at the same time without creating circular dependencies. Also, it is not immediately clear how to make a donation conditional on other donations to multiple charities when the donor has different levels of appreciation for the different charities. In both these cases, the limited expressiveness of matching offers causes economic loss: it may happen that an arrangement that all parties (donors as well as charities) would have preferred cannot be expressed in terms of matching offers and will therefore not occur.In this paper, we introduce a bidding language for expressing very general types of matching offers over multiple charities. We formulate the corresponding clearing problem (deciding how much each bidder pays, and how much each charity receives), and show that it cannot be approximated to any ratio in polynomial time unless P = NP, even in very restricted settings. We give a mixed integer program formulation of the clearing problem, and show that for concave bids, the program reduces to a linear program. We then show that the clearing problem for a subclass of concave bids is at least as hard as the decision variant of linear programming. We also consider the case where each charity has a target amount, and bidders? willingness-to-pay functions are concave. Here, we show that the optimal surplus can be approximated to a ratio m, the number of charities, in polynomial time (and no significantly better approximation is possible in polynomial time unless P = NP); no polynomial-time approximation ratio is possible for maximizing the total donated, unless P = NP. Subsequently, we show that the clearing problem is much easier when bids are quasilinear—for maximizing surplus, the problem decomposes across charities, and for maximizing the total donated, a greedy approach is optimal if the bids are concave (although this latter problem is weakly NP-hard when the bids are not concave). For the quasilinear setting, we study the mechanism design question. We show that an ex-post efficient mechanism is impossible even with only one charity and a very restricted class of bids. We also show that there can be benefits to linking the charities from a mechanism design standpoint. Finally, we discuss an experiment in which we used this methodology to collect money for victims of the 2004 Indian Ocean Tsunami. 相似文献