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991.
SM Stick PR Burton L Gurrin PD Sly PN LeSou?f 《Canadian Metallurgical Quarterly》1996,348(9034):1060-1064
INTRODUCTION: Infants of mothers who smoke have reduced respiratory function and are more likely to develop wheezing. Little evidence is available on the effect of in-utero cigarette-smoke exposure as opposed to postnatal exposure to environmental tobacco smoke. We used a previously validated non-invasive method to measure the time to peak tidal expiratory flow (tPTEF) as a proportion of expiratory time (tE) in newborn infants soon after birth to examine the effects of a family history of asthma and in-utero cigarette-smoke exposure on the infants' respiratory function. METHODS: We collected respiratory-function data from 500 healthy infants of mothers taking part in the Western Australia Pregnancy Cohort Study. During behaviourally defined quiet sleep, measurements were obtained a median of 58 h (range 26-159) after the infants were born. We used uncalibrated inductance plethysmography. The uncalibrated volume signal was differentiated to flow and used to calculate respiratory rate, total inspiratory time, tE, and tPTEF. Mothers answered questionnaires on demographic, medical, and pregnancy characteristics, including smoking history. Serum cotinine measurements were available to validate self-reported smoking history in a subset of mothers (238). RESULTS: Data suitable for analysis were obtained from 461 infants. In multivariate regression analysis, lower values of tPTEF/tE were independently associated with respiratory rate (beta coefficient per 10 breaths/min 0.018 [SE 0.005], p < 0.01), age (beta coefficient per 10 h -0.008 [0.003], p < 0.01), maternal smoking during pregnancy (> 10 cigarettes daily; beta coefficient -0.049 [0.022], p < 0.05), maternal hypertension during pregnancy (-0.037 [0.015], p < 0.02), and a family history of asthma (-0.028[0.014], p < 0.05). CONCLUSIONS: In-utero smoke exposure, a family history of asthma, and maternal hypertension during pregnancy are associated with reduced respiratory function after birth. We speculate that these factors adversely affect lung development in utero. 相似文献
992.
Two methods are demonstrated for obtaining the quasi-static C-V curves of an MIS structure containing a non-ideal insulator. Compensation for current leakage in the insulator is achieved by taking the difference in the total currents obtained for each polarity of the ramp voltage. In the second method, the compensated C-V curve is obtained by subtracting off the leakage current which is directly measured by scanning the bias voltage in a step-wise fashion. Tests to determine when these methods are successful are also discussed. 相似文献
993.
Describes modifications of the psychoanalytic approach to benefit adults who, because of acting-out behavior, are considered not amenable to psychotherapy. Case profiles of 2 males, one who could not be faithful in marriage and the other who was involved in dangerous promiscuity, are presented as examples. Four principles (avoiding limit setting, extending perspectivism, maintaining active interest, and setting achievable goals) for working with such patients are presented. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
The predictions from two simple field equation models for calculating temperature distributions in tissue, namely, the Pennes' bioheat transfer equation (BHTE) and an effective thermal conductivity equation (ETCE), were compared to in vivo experimental temperature measurements made under hyperthermic conditions generated by scanned focused ultrasound. The models were kept simple (i.e. homogenous isotropic properties, no separate blood vessels included) in order to concentrate attention on the predictive abilities of these field equations using a minimum number of free parameters. Simulated results were fitted to the experimental data (multiple, linear temperature profiles in the thigh muscles of greyhound dogs) by minimizing a performance index using a golden section searth. This search determined a value for the single free parameter in each model (blood perfusion in the BHTE, and effective thermal conductivity in the ETCE) which minimized the square error difference between the experimental and simulated temperatures. The results showed that (a) the simple BHTE model could qualitatively reproduce the major features of the temperature patterns seen experimentally better than the ETCE model could, and (b) the simple BHTE model produced better quantitative fits to the experimental data than did the simple ETCE model. In addition, blood perfusion predictions from the BHTE model compared well to measurements done with coloured microspheres. Finally, the experimental results showed that individual, large blood vessels appeared to have a major influence in producing asymmetries in the experimental data in 21% of the measured temperature profiles. 相似文献
995.
996.
Burton Martha W.; Baum Shari R.; Blumstein Sheila E. 《Canadian Metallurgical Quarterly》1989,15(3):567
This study examines the extent to which acoustic parameters contribute to lexical effects on the phonetic categorization of speech. Experiment 1 was designed to replicate previous findings. Two test continua were created varying in voice onset time. Results of both identification and reaction time (RT) range data showed an effect of lexical status at the phonetic boundary, but only in the slowest RT ranges, suggesting that lexical effects on phonetic categorization are postperceptual. Experiment 2 explored whether the lexical effect would emerge when the stimulus continua more nearly approximated the parameter values of natural speech. Both identification and RT range data indicated that the lexical effect disappeared. These results suggest that without attention to the acoustic structure of the stimuli, the role of top–down processing in phonetic categorization may be overemphasized. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
N. B. B. Obasi A. C. Igboechi T. V. Benjamin 《Journal of the American Oil Chemists' Society》1990,67(10):624-625
The fixed oil ofThevetia peruviana (Pers.) K. Schum. (T. neriifolia Juss) was obtained by solvent extraction, and its yield and composition were studied to reflect the effect of seasonal variations.
Ripe and unripe seeds collected in December and February (the dry season) gave average yields of 72 and 52%, v/w, respectively,
and those of May and August (the rainy season) gave 56 and 41%, v/w, respectively.
Sitosterol was isolated and identified from the unsaponifiable fraction. Oleic, linoleic, stearic and palmitic acids were
shown to be present in all the oils, while myristic, lauric, capric and caprylic acids were identified only in the oil from
unripe seeds collected in the rainy season. The physical and chemical constants of the oils are given also. 相似文献
998.
A Tomie C Cunha EM Mosakowski NM Quartarolo LA Pohorecky D Benjamin 《Canadian Metallurgical Quarterly》1998,139(1-2):154-159
Approach responses, consummatory behaviors, and directed motor responses maintained by food reward resemble autoshaping CRs and are increased by lower doses of ethanol. This study evaluated the effects of presession i.p. injections of ethanol doses (0.00, 0.25, 0.50, 0.70. or 1.00 g/kg) on the acquisition of lever-press autoshaping CR performance in groups of male Long-Evans hooded rats. Paired groups received 15 daily sessions of Pavlovian autoshaping procedures, wherein the insertion of a retractable lever for 5 s (CS) was followed by the response-independent presentation of food (US). Ethanol facilitated lever-press autoshaping CR acquisition, as revealed by dose-related increases in the number of trials on which CRs were performed. The form of the dose-effect curve was inverted U-shaped with maximal responding induced during sessions 1-5 by the 0.70 g/kg ethanol dose. A similar dose-effect curve was observed during sessions 11-15, revealing that the effects of ethanol on autoshaping CR performance were relatively stable. A pseudoconditioning control group injected presession with 0.50 g/kg ethanol received training wherein the food US was presented randomly with respect to the lever CS. Few lever-presses were performed by the Random 0.50 group, indicating that ethanol's effects on autoshaping CR acquisition and maintenance observed in the Paired 0.50 group were not due to its psychomotor activating effects. A non-injection control group performed more autoshaping CRs than did the control group injected presession with saline, indicating that daily presession i.p. injections per se suppress autoshaping CR performance. Results reveal that low doses of ethanol enhance Pavlovian conditioning of directed motor and consummatory-like responding maintained by food reward. Implications for autoshaping accounts of impulsivity and drug abuse are considered. 相似文献
999.
DR Benjamin CV Robinson JP Hendrick FU Hartl CM Dobson 《Canadian Metallurgical Quarterly》1998,95(13):7391-7395
Nanoflow electrospray ionization has been used to introduce intact Escherichia coli ribosomes into the ion source of a mass spectrometer. Mass spectra of remarkable quality result from a partial, but selective, dissociation of the particles within the mass spectrometer. Peaks in the spectra have been assigned to individual ribosomal proteins and to noncovalent complexes of up to five component proteins. The pattern of dissociation correlates strongly with predicted features of ribosomal protein-protein and protein-RNA interactions. The spectra allow the dynamics and state of folding of specific proteins to be investigated in the context of the intact ribosome. This study demonstrates a potentially general strategy to probe interactions within complex biological assemblies. 相似文献
1000.
This paper challenges the notion that undergraduate engineering education is simply about learning content and suggests, to those responsible for engineering courses, ways of thinking about teaching, learning and assessing which might help students to learn more effectively 相似文献