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31.
Identification of Components of Male-Produced Pheromone of Coffee White Stemborer, Xylotrechus quadripes 总被引:2,自引:0,他引:2
Hall DR Cork A Phythian SJ Chittamuru S Jayarama BK Venkatesha MG Sreedharan K Vinod Kumar PK Seetharama HG Naidu R 《Journal of chemical ecology》2006,32(1):195-219
The coffee white stem borer, Xylotrechus quadripes Chevrolat (Coleoptera: Cerambycidae), is the foremost pest of arabica coffee in India, Sri Lanka, China, Vietnam, and Thailand.
Previous work showed that female beetles were attracted to traps baited with male beetles. Analyses of volatiles from male
X. quadripes of Indian origin by gas chromatography (GC) linked to electroantennographic (EAG) recording from a female beetle antenna
showed three male-specific components comprising more than 90% of the volatiles, two of which elicited EAG responses. The
major EAG-active component was produced at up to 2 μg hr−1 insect−1 and was identified as (S)-2-hydroxy-3-decanone (I) by comparison of GC data, and mass (MS), infrared, and nuclear magnetic resonance (NMR) spectra with those of synthetic
standards. The second component was identified as 3-hydroxy-2-decanone (II) produced in part by isomerization of I under the conditions of the GC analysis, although the NMR spectrum suggested it is naturally produced at up to 7% of I. The minor component that elicited an EAG response, present at 7% of the amount of I, was identified as (S,S)-2,3-dihydroxyoctane (III) from GC and MS data. 2-Hydroxy-3-octanone (0.2–0.5% of I), 2,3-decanedione (2% of I), 2-phenylethanol (3% of I), and octanoic acid (4% of I) were also identified in volatiles from male beetles. A general, stereospecific synthetic route to the enantiomers of 2-hydroxy-3-alkanones
from the enantiomers of ethyl lactate was developed. The enantiomers of III were synthesized from (E)-2-octene by Sharpless asymmetric dihydroxylation. (S)-(I) was attractive to male X. quadripes in laboratory bioassays, but addition of (S,RS)-(III) at 10% of I reduced attractiveness. In field trials carried out in India with sticky, cross-vane traps, (S)- and (RS)-(I) attracted male X. quadripes and addition of (S,S)-(III) at 10% of I reduced attractiveness. Significant numbers of female Demonax balyi Pascoe (Coleoptera: Cerambycidae) were sometimes caught in traps baited with (S)-(I) alone. 相似文献
32.
William Ong Nicolas Marinval Junquan Lin Mui Hoon Nai Yee‐Song Chong Coline Pinese Sreedharan Sajikumar Chwee Teck Lim Charles Ffrench‐Constant Marie E. Bechler Sing Yian Chew 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(37)
A key hallmark of many diseases, especially those in the central nervous system (CNS), is the change in tissue stiffness due to inflammation and scarring. However, how such changes in microenvironment affect the regenerative process remains poorly understood. Here, a biomimicking fiber platform that provides independent variation of fiber structural and intrinsic stiffness is reported. To demonstrate the functionality of these constructs as a mechanotransduction study platform, these substrates are utilized as artificial axons and the effects of axon structural versus intrinsic stiffness on CNS myelination are independently analyzed. While studies have shown that substrate stiffness affects oligodendrocyte differentiation, the effects of mechanical stiffness on the final functional state of oligodendrocyte (i.e., myelination) has not been shown prior to this. Here, it is demonstrated that a stiff mechanical microenvironment impedes oligodendrocyte myelination, independently and distinctively from oligodendrocyte differentiation. Yes‐associated protein is identified to be involved in influencing oligodendrocyte myelination through mechanotransduction. The opposing effects on oligodendrocyte differentiation and myelination provide important implications for current work screening for promyelinating drugs, since these efforts have focused mainly on promoting oligodendrocyte differentiation. Thus, the platform may have considerable utility as part of a drug discovery program in identifying molecules that promote both differentiation and myelination. 相似文献
33.
L Chambers A Brown DI Pritchard S Sreedharan K Brocklehurst NA Kalsheker 《Canadian Metallurgical Quarterly》1998,253(3):837-840
Human exposure to papain, a cysteine proteinase, is associated with hypersensitivity reactions. We demonstrate in mice that enzymatically active papain preferentially induces an IgG1 response and results in mast cell degranulation, both features typical of an allergic reaction. Inactive papain, blocked with E-64, appears to desensitize mice to subsequent challenge by active enzyme. These results suggest that the enzymatic activity of papain is critical in inducing an allergic response and that the use of inactive allergens may be a possible strategy for desensitizing allergic individuals. 相似文献
34.
Towards improved characterization of high-risk releases using heterogeneous indoor sensor systems 总被引:1,自引:0,他引:1
The sudden release of toxic contaminants that reach indoor spaces can be hazardous to building occupants. For an acutely toxic contaminant, the speed of the emergency response strongly influences the consequences to occupants. The design of a real-time sensor system is made challenging both by the urgency and complex nature of the event, and by the imperfect sensors and models available to describe it. In this research, we use Bayesian modeling to combine information from multiple types of sensors to improve the characterization of a release. We discuss conceptual and algorithmic considerations for selecting and fusing information from disparate sensors. To explore system performance, we use both real tracer gas data from experiments in a three-story building, along with synthetic data, including information from door-position sensors. The added information from door-position sensors is found to be useful for many scenarios, but not always. We discuss the physical conditions and design factors that affect these results, such as the influence of the door positions on contaminant transport. We highlight potential benefits of multisensor data fusion, challenges in realizing those benefits, and opportunities for further improvement. 相似文献
35.
36.
The use of thermodynamic data in the calculation of limiting oxygen pressures for the existence of ternary oxides is demonstrated in the case of LaMO3 and La2MO4 (M=Mn, Fe, Co, Ni or Cu) compounds using the literature data on the relevant chemical equilibria. The standard Gibbs' energy of formation, G
f
0
, of LaCuO3 is estimated from the values of G
f
0
of the other LaMO3 compounds calculated from the literature and is given as
(kJ mol–1)= –1095.0+0.2351 T (K). The validity of this expression is qualitatively verified with the help of experimental conditions reported in the literature for the synthesis of this compound. Similar considerations are used to predict values of 0.03 and 30 atm to be the oxygen pressure range for the existence of a quarternary compound, YBa2Cu3O9–y
at 1273 K. The superconducting transition temperature, T
c, is qualitatively predicted to show a maximum for the sample annealed under an oxygen pressure in the range 1 to 30 atm at 1273 K. 相似文献
37.
S.K. Chaturvedi T.M. Abdel-Salam S.S. Sreedharan F.B. Gorozabel 《Applied Thermal Engineering》2009,29(10):2093-2099
Direct expansion solar-assisted heat pump (DX-SAHP) systems have been proposed as viable alternatives to conventional solar-assisted heat pump systems. This study proposes the use of two-stage DX-SAHP systems for high temperature applications in the range of 60–90 °C. The study investigates the capability of these systems of meeting loads with high temperature requirements. The thermal performance of the systems is analyzed for refrigerant R-134a, using a one-cover solar collector. Comparisons between the two-stage DX-SAHP and the single-stage DX-SAHP systems are performed and presented. A graphical procedure is illustrated and used for sizing the solar collector area and the heat pump compressor displacement capacity for the two DX-SAHP systems. 相似文献
38.
39.
40.
R. Subasri T. Mathews K. Swaminathan O. M. Sreedharan 《Journal of Nuclear Materials》2002,300(2-3):237-241
The sodium potential in the test electrode (a) Pt,O2,Na2ZrO3,ZrO2 was measured by using the emf technique employing Na-β″-alumina as the solid electrolyte in conjunction with (b) Pt,O2,Al2O3,NaAl11O17, (c) Pt,O2,Na2MoO4,Na2Mo2O7 and (d) Pt,Na2CO3,CO2,O2 as the reference electrodes over the ranges 880–1045, 700–800 and 850–940 K, respectively. The emf results between electrodes (b) and (c) were utilized for internal consistency checks. From the results on cells formed between (a) and (b) and those on (a) and (c), the standard Gibbs energy of formation, ΔfGo (kJ/mol) of Na2ZrO3 was determined to be −1699.4+0.3652T (K) valid over the temperature range 700–1045 K. The break in the emf data at 1045 K was corroborated by independent TG/DTA measurements carried out on Na2ZrO3 which exhibited an endotherm at 1055 K indicative of a phase transition in Na2ZrO3. 相似文献