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51.
Speech perception tests are an important part of procedures for diagnosing pre-verbal hearing loss. Merely establishing a child's hearing threshold with and without a hearing aid is not sufficient to ensure an adequate evaluation with a view to selecting cases suitable for cochlear implants because it fails to indicate the real benefit obtained from using a conventional hearing aid reliably. Speech perception tests have proved useful not only for patient selection, but also for subsequent evaluation of the efficacy of new hearing aids, such as tactile devices and cochlear implants. In clinical practice, the tests most commonly adopted with small children are: The Auditory Comprehension Test (ACT), Discrimination after Training (DAT), Monosyllable, Trochee, Spondee tests (MTS), Glendonald Auditory Screening Priocedure (GASP), Early Speech Perception Test (ESP), Rather than considering specific results achieved in individual cases, reference is generally made to the four speech perception classes proposed by Moog and Geers of the CID of St. Louis. The purpose of this classification, made on the results obtained with suitably differentiated tests according to the child's age and language ability, is to detect differences in perception of a spoken message in ideal listening conditions. To date, no italian language speech perception test has been designed to establish the assessment of speech perception level in children with profound hearing impairment. We attempted, therefore, to adapt the existing English tests to the Italian language taking into consideration the differences between the two languages. Our attention focused on the ESP test since it can be applied to even very small children (2 years old). The ESP is proposed in a standard version for hearing-impaired children over the age of 6 years and in a simplified version for younger children. The rationale we used for selecting Italian words reflect the rationale established for the original version, but the choice of single words follows different criteria from the original version. In fact, the two languages differ in important linguistic features so that the test can not be not adapted to the Italian language by simply translating the words involved. As currently there is no children's language dictionary in Italian arranged according to age bracket, we chose words used in children and in pre-school reading material.  相似文献   
52.
This paper presents an analysis of the vertical Bell Laboratories layered space time (VBLAST) receiver used in a multiple-input multiple-output (MIMO) wireless system from the hardware implementation perspective and identifies those processing elements that consume more area and power due to complex signal processing. This paper models a scalable VBLAST receiver based on minimum mean square error (MMSE) nulling criteria assuming a block flat fading channel. After identifying the major area and power consuming blocks, this paper proposes two area and power efficient VLSI architectures for the block that computes pseudoinverse of the channel matrix. This paper discusses different tradeoff issues in both architectures and compares them with the architectures in the literature  相似文献   
53.
The structure and surface morphology of Ni-incorporated diamond like carbon (Ni:DLC) films have been investigated. These films were deposited on Si substrates using pulsed laser deposition (PLD) technique. A KrF Excimer laser (λ = 248 nm) was used for co-ablation from multi component Ni–graphite target. The concentration of Ni was varied by ablating the Ni part of the target with various numbers of laser pulses. The SEM and AFM analysis reveals that the surface is composed of segregates of Ni which increases with the increase in Ni content during the growth process. The structural investigations by XRD and Raman spectroscopy provided information about the orientation of the incorporated constituent and the ordering of the carbon species. Maximum height of the nano structures which were observed on the surface was ∼50 nm. The G-peak of the graphite was shifted towards higher wave number due to enhancement in SP2 sites which have been increased due to the increase in the Ni concentration. A small change in the surface roughness ranging from 7.78 nm to 13.1 nm due to increased Ni concentration was also observed.  相似文献   
54.
Vegetable oils have chances to be used in Diesel engines as alternative fuels contributing to the solution of some agricultural, environmental and economical problems. Direct use of them has some technical problem yet but as blended fuels with diesel fuel or esters they have places on the application area. In this paper the effect of the compression ratio on ignition delay is investigated in an ASTM-CER engine working with four different types of vegetable oil of Turkish origin (sunflower, corn, soybean, and olive oil) blended with grade No.2-D diesel fuel at a ratio of 20/80 (v/v) and the results are compared with baseline diesel fuel. Longer ignition delay periods have generally been obtained for blend fuels ranking from olive oil to sunflower oil as compared to diesel fuel.  相似文献   
55.
Theoretical analysis of time-of-arrival (TOA)-based high-precision ranging algorithm for the dynamic spectrum access networks (DSANs) is performed. The asymptotic frequency-domain Cramer-Rao bound (CRB) of the ranging algorithm that takes the frequency-dependent feature (FDF) and phase of multipath components (MPCs) into account is derived through Whittle formula. The effects of FDF-MPCs and related parameters such as absolute bandwidth and operating center frequency on the ranging accuracy are investigated. The results show that the impacts of the FDF-MPCs on the ranging accuracy can be significant and it is recommended utilizing as large absolute bandwidth as possible at low operating center frequencies to obtain high-precision distance information of the users in the DSANs  相似文献   
56.
Loyalty to one's extended family, a well-known Japanese tradition, has broken down following World War II. Child rearing in Japan, therefore, has been changing gradually and clearly. Traditionally, child rearing was taught to young mothers by the grandmothers. However, recently young couples are no longer living with their parents. Therefore, there are no advisers nor consultants available at home for their child rearing. Commercialism has certainly invaded the field of child rearing, including too many guidebooks and even baby-sitting companies. Children's lives have become much more competitive, busy and unnatural in comparison with those of 20-30 years ago. This might be one cause of the increased incidence of bullying, school phobia and psychological disorders in children.  相似文献   
57.
A sound in-plant pollution control strategy can only be defined by paying due attention to bio-recalcitrance and toxicity. In this context the levels of toxicity and inert COD introduced to textile dyebath discharges by two alternative auxiliary chemicals, namely natural tannin (NT) and synthetic tannin (ST), were investigated. The effect of 40 minutes ozonation at 1,000 mg h(-1) at pH 3.5 on the segregated effluent streams containing the above-mentioned tannin formulations was evaluated in terms of changes in toxicity and recalcitrance. The effect of ozonation on the COD distribution of raw and ozonated NT and ST samples according to their molecular weight cut-offs was also assessed. Both untreated tannin formulations exerted high acute toxicity towards marine microalgae Phaeodactylum tricornutum. Moderate decrease in the toxicity levels of both tannins was observed upon ozonation. The raw NT formulation with a COD content more than twice that of its alternative raw ST had an initially inert soluble COD content of only 25 mg/L, while the initially inert COD was 135 mg/L for ST. As the initially inert soluble COD content of NT was considerably lower, this textile auxiliary did not need chemical pretreatment to improve its biodegradability. On the other hand, the initially inert soluble COD content of ST was reduced by 70% by ozone pretreatment. In terms of residual COD contents achievable after passing through a biological treatment system, raw NT and pretreated ST formulations yielded 100 and 95 mg/L COD, respectively. The highest proportion of COD (46% for NT and 88% for ST) was found in the <1 kDa range. The same fraction increased to 93% for NT after ozonation, while for ST no significant change was observed in the COD distribution of the molecular weight cut-offs after ozonation.  相似文献   
58.
A test procedure developed to determine the mixed-mode impact resistance of fibre reinforced concrete materials is described. Results are presented from a series of experiments using a repeated drop-weight impact apparatus for the impact resistance of both polypropylene and steel fibre reinforced concrete. The behaviour of the mixed-mode specimen geometry was investigated under impact loading condition. The effect of the fibre types and contents on the impact fracture energy of the specimens was investigated. A close investigation was made of the positions and formations of the crack patterns. The fracture performance of the plain and fibre reinforced concrete was investigated with the proposed geometry using 1.0, 2.0 and 3.0% by weight in the case of steel fibre, and 0.1, 0.2 and 0.3% by weight in the case of polypropylene fibre.
Resume Aux charges statiques auxquelles les structures en béton sont soumises s'ajoutent souvent des charges dynamiques, parfois significatives, qu'il convient de prendre en compte dans le calcul. Cet article décrit un mode opératoire visant à déterminer la résistance au choc en mode mixte de béton renforcé de fibres (FRC). On y présente les résultats d'une série d'essais utilisant une machine d'essai au choc à répétition (mouton) pour évaluer la résistance de béton renforcé de fibres d'acier et de fibres de polypropylène. On a mis au point une géométrie d'éprouvettes en mode mixte qu'on a soumises à des essais au choc, et on a étudié l'effet des types et des pourcentages de fibres sur la résistance des éprouvettes à la rupture par choc. On s'est aussi livré à une étude précise des emplacements et de la formation des fissures. On a examiné la résistance à la rupture de béton ordinaire et de béton de fibres dans la géométrie proposée avec des pourcentages de 1, 2 et 3% en poids de fibres d'acier, et de 0,1, 0,2 et 0,3% pour les fibres de polypropylène.
  相似文献   
59.
Polyphenol oxidase (PPO) was purified from Boletus erythropus using a Sepharose 4B-L-tyrosine-p-amino benzoic acid affinity column. Optimum pH and temperature were found to be 8.0 and 20 °C, respectively, using 4-methylcatechol as a substrate. The enzyme was extremely stable between pH 3.0 and 9.0 after 24 h incubation at 4 °C. B. erythropus PPO was also quite stable between 10 and 30 °C after 4 h incubation. The Km and Vmax values were calculated as 2.8 mM and 1430 U/mg protein by Lineweaver–Burk curve, respectively. The enzyme activity was inhibited by sodium metabisulfite, ascorbic acid, sodium azide and benzoic acid. It was seen that the mushroom PPO was an effective biocatalyst in selected organic solvents, such as dichloromethane, dichloroethane and toluene, when catechin was used as a substrate. All data support that B. erythropus has a highly active PPO, possessing similar biochemical and kinetic characteristics to other plant PPOs.  相似文献   
60.
A potential candidate that can be used for emulating different propagation environments is the reverberation chamber (RVC). Since mobility is of primary concern for wireless communication systems, understanding of its consequences is crucial. Mobility causes spectral broadening whose impact is generally evaluated through the observation of Doppler spectrum. In this study, investigation of Doppler spectrum characteristics through the use of an RVC and the methods for the purpose of its manipulation are presented. This study verifies that the Doppler spectrum can be manipulated in various ways. However, unless a precise setup is established it is almost impossible to obtain very specific Doppler shapes in RVCs such as widely known Jakes’ spectrum. Also, a different interpretation of mobility for wireless channels is given by the use of a new concept called motion intensity. This concept is elaborated in terms of both its technical aspects and its impact on wireless channel characterization.  相似文献   
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