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321.
Group cohesion is an important construct in understanding the behavior of different types of groups. However, controversy exists about how to conceptualize and measure cohesion, and a central issue is its dimensionality. Consequently, researchers have used factor analysis to examine the structure of the construct of cohesion and measures of it. Our goals in writing this article were to review critically how factor analysis has been used to understand group cohesion, make some recommendations for future factor analytic work, and point out some weaknesses and strengths in using factor analysis to explore cohesion. 相似文献
322.
A new series of phases MICa2Nb3O10 (MI = Li, Na, K, Rb, Cs, NH4, Tl) has been prepared and characterized. Their unit cells are tetragonal. The structures consist of treble perovskite sheets interleaved with MI sheets. According to the MI nature, the relative displacement of adjacent treble perovskite sheets, parallel to (001) is O, or 相似文献
323.
Bosilevac JM Nou X Barkocy-Gallagher GA Arthur TM Koohmaraie M 《Journal of food protection》2006,69(8):1808-1813
Lactic acid has become the most commonly used organic acid for treatment of postevisceration beef carcasses. Many processors have also implemented 2% lactic acid washes on preevisceration carcasses. We previously demonstrated that hot water washing and steam vacuuming are effective carcass interventions. Because of the effectiveness of hot water, we compared its use with that of lactic acid as a preevisceration wash in a commercial setting. A commercial hot water carcass wash cabinet applying 74 degrees C (165 degrees F) water for 5.5 s reduced both aerobic plate counts and Enterobacteriaceae counts by 2.7 log CFU/100 cm2 on preevisceration carcasses. A commercial lactic acid spray cabinet that applied 2% L-lactic acid at approximately 42 degrees C (105 to 110 degrees F) to preevisceration carcasses reduced aerobic plate counts by 1.6 log CFU/100 cm2 and Enterobacteriaceae counts by 1.0 log CFU/100 cm2. When the two cabinets were in use sequentially, i.e., hot water followed by lactic acid, aerobic plate counts were reduced by 2.2 log CFU/100 cm2 and Enterobacteriaceae counts were reduced by 2.5 log CFU/100 cm2. Hot water treatments reduced Escherichia coli O157:H7 prevalence by 81%, and lactic acid treatments reduced E. coli O157:H7 prevalence by 35%, but the two treatments in combination produced a 79% reduction in E. coli O157:H7, a result that was no better than that achieved with hot water alone. These results suggest that hot water would be more beneficial than lactic acid for decontamination of preevisceration beef carcasses. 相似文献
324.
Atchison DA Scott DH Charman WN 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(9):2963-2973
We have used the Hartmann-Shack technique previously to measure ocular aberrations along the horizontal meridian of the visual field. This requires considerable modifications from the technique for measuring the aberrations corresponding to the fovea. We now further develop the technique so that it can be used for any meridian of the visual field. Allowance is made for any auxiliary optics placed in front of the eye to compensate for the limited range of the Hartmann-Shack technique and for the case where aberrations are estimated at a wavelength other than the measuring wavelength. Zernike wave aberrations are converted to peripheral refractions. Examples are presented showing the developments, and we discuss change in wave aberrations when converting from a circular to an elliptical pupil. 相似文献
325.
Off-axis reciprocal-space mapping was performed on aluminum gallium nitride deep-ultraviolet light-emitting diode base layers.
The results indicate that aluminum gallium nitride films growing on aluminum nitride-on-sapphire templates initially grow
in compression, nearly lattice matched to the relaxed aluminum nitride buffer layer with approximately 0.5% biaxial strain.
This compressive strain may be partially relieved over the course of the thick aluminum gallium nitride growth when a high-quality
aluminum nitride and superlattice layer is used. Additionally, a growth interruption appears to allow growth of an unstrained
aluminum gallium nitride layer without a gradual release of compressive strain. Growth on a bulk aluminum nitride substrate
appears to yield an aluminum gallium nitride layer in tension rather than compression. 相似文献
326.
Repurposing the Chemical Scaffold of the Anti‐Arthritic Drug Lobenzarit to Target Tryptophan Biosynthesis in Mycobacterium tuberculosis 下载免费PDF全文
Dr. Genevieve L. Evans Dr. Swarna A. Gamage Dr. Esther M. M. Bulloch Prof. Edward N. Baker Prof. William A. Denny Assoc. Prof. J. Shaun Lott 《Chembiochem : a European journal of chemical biology》2014,15(6):852-864
The emergence of extensively drug‐resistant strains of Mycobacterium tuberculosis (Mtb) highlights the need for new therapeutics to treat tuberculosis. We are attempting to fast‐track a targeted approach to drug design by generating analogues of a validated hit from molecular library screening that shares its chemical scaffold with a current therapeutic, the anti‐arthritic drug Lobenzarit (LBZ). Our target, anthranilate phosphoribosyltransferase (AnPRT), is an enzyme from the tryptophan biosynthetic pathway in Mtb. A bifurcated hydrogen bond was found to be a key feature of the LBZ‐like chemical scaffold and critical for enzyme inhibition. We have determined crystal structures of compounds in complex with the enzyme that indicate that the bifurcated hydrogen bond assists in orientating compounds in the correct conformation to interact with key residues in the substrate‐binding tunnel of Mtb‐AnPRT. Characterising the inhibitory potency of the hit and its analogues in different ways proved useful, due to the multiple substrates and substrate binding sites of this enzyme. Binding in a site other than the catalytic site was found to be associated with partial inhibition. An analogue, 2‐(2‐5‐methylcarboxyphenylamino)‐3‐methylbenzoic acid, that bound at the catalytic site and caused complete, rather than partial, inhibition of enzyme activity was found. Therefore, we designed and synthesised an extended version of the scaffold on the basis of this observation. The resultant compound, 2,6‐bis‐(2‐carboxyphenylamino)benzoate, is a 40‐fold more potent inhibitor of the enzyme than the original hit and provides direction for further structure‐based drug design. 相似文献
327.
C. Commault J. M. Dion D. H. Trinh T. H. Do 《International Journal of Adaptive Control and Signal Processing》2011,25(1):1-17
This paper addresses the sensor classification problem for fault detection and isolation (FDI) with observability requirement in a structural way. The system under consideration is a linear system subject to additive faults and affected by unknown input disturbances. This system is equipped with a sensor network subject to sensor failures. We represent the dynamics of the system by a linear parameterized state space model called linear structured model. The underlying prior knowledge on the system is reduced to the existence or non‐existence of relations between variables in the model. A dedicated residual set using a bank of observers is designed in order to detect and isolate the faults. The failure of some sensors may affect the observability of the system which is a natural requirement in order to build stable observers and also may affect the FDI solvability. The main contribution of this paper is to classify the sensors with respect to their importance in case of failure relatively to the considered FDI problem. More precisely, we characterize the sensors that are essential i.e. whose failure leads to FDI solvability loss and those which are useless for such property. We also quantify the relative importance of the sensors which are not useless. The proposed graph approach is visual, easy to handle and close to the physical structure of the system. It is well adapted to large‐scale systems and essentially leads to polynomial algorithms here. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
328.
The incorporation of carbon nanotubes to thermoplastic fibers can potentially improve mechanical, thermal and electrical properties. In this article, a methodology to tailor the mechanical properties of carbon nanotube/nylon fibers is presented. Multiwalled nanotubes (MWNT) were combined to polyamide 12 through melt compounding and twin‐screw extrusion. Pellets containing between 0 and 5.0 wt % MWNT were extruded and subsequently melt spun with a capillary rheometer to produce filaments. To further promote the alignment of the polymer chains and MWNTs, postdrawing parameters were systematically investigated: temperature, drawing speed and elongation. The best improvements in terms of elastic modulus and yield strength were measured at 140°C and 500% elongation, whereas drawing speed was shown to have a negligible effect. It was confirmed through electron microscopy and X‐ray diffraction that these enhancements were mainly induced by the alignment of the polymer chains along the fibers' axis. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4375–4382, 2013 相似文献