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61.
62.
Placing text on the graphics screen in any size any angle is an important function of a graphics program. Some microcomputers, however, will not print characters on the graphics screen, and others have very limited ability, such as printing only in 40-character or 80-character mode. Characters are needed for dimensions and notes on the drawing as well as for prompts and messages. Alternate fonts, rotation of the text, and different sizes of text are needed for many applications, not to mention text that is scaled up and down as the user zooms in or out to magnify or reduce the size of the image. This article examines available techniques and discusses the advantages and disadvantages of each. A method is presented for producing stroke generated text by designing each character as a matrix of dots on a standard grid and storing the coordinates of the dots as endpoints of vectors to be used to draw the character. The standard grid is assumed to have its origin in the lower left corner and each coordinate is defined relative to that origin.  相似文献   
63.
This article clarifies key concepts that undergird qualitative research, which is being used increasingly as engineering educators improve classrooms, programs, and institutions. The paper compares quantitative and qualitative research, describes some qualitative data collection strategies used in engineering education, addresses methods for establishing trustworthiness, and discusses strategies for analyzing qualitative data. Also included are illustrative examples of recent engineering education research that features qualitative data analysis and mixed‐method (quantitative and qualitative) approaches.  相似文献   
64.
CADD software and other large, highly interactive, complex programs must keep track of many complex relationships and perform the correct operations with both speed and precision based on these relationships, which are often seemingly in conflict. Computers can evaluate only one relationship at a time and the relationships must be evaluated in a specified order that can vary greatly depending on the outcome of each test. Consequently, writing and debugging a program that will perform correctly under a wide variety of inputs can be a frustrating process that at times can seem to produce two "bugs" for each one that is corrected. Tree structures can be employed to maintain a dynamic diagram of the program structure as it is being created. Graph structures, which are closely associated with tree structures, can be employed to simplify the task of developing and implementing the correct program logic and to identify many of the design logic errors at an early stage.
This article describes the use of tree and graph structures to diagram program structure and logic for an educational CADD package that was written by the author.  相似文献   
65.
This paper considers computer programs that purport to do inference. It finds the essence of their reasoning ability to reside in a particular relationship which exists between the computations described by the texts of those programs and machine-independent formal representations of the theories in which they are said to reason. The principal novelties in the treatment of this question are the use of explicit “abstraction functions” between states of a computation and sets of sentences of a theory, and the notion of global “inference relations” which characterize the set of all inferences of which a system is capable. The central result of the paper is an “arrow-theoretic” characterization of the concept of a knowledge representation, along with the related concept of a knowledge representation realization. The notions of equivalence and subsumption for knowledge representations are defined, as well as equivalence of knowledge representation realizations. Finally, important issues of expression evaluation and control are addressed. The paper concludes with a slogan: “The AI is in the arrows.” Cet article traite des programmes informatiques qui prétendent faire de ľinférence. Ľauteur constate que ľessentiel de leur capacityé de raisonnement réside dans la relation particulière qui existe entre les calculs décrits par les textes de ces programmes et les représentations formelles non liées à un type de machine des théories dans le cadre desquelles ils sont supposés raisonner. Les principales nouveautés dans le traitement de cette question sont ľutilisation de fonctions ?abstraction explicites éntre les etats ?un calcul et les ensembles de phrases ?une théorie, et la notion de relations ?inférence globales qui caractérisent ľensemble de toutes les inférences dont un système est capable. Le principal résultat de cet article est une caractérisation du concept de la représentation des connaissances, ainsi que du concept connexe de la réalisation de la représentation des connaissances. Les notions ?équivalence et de sous-somption pour la représentation des connaissances sont définies, ainsi que ľéquivalence des réalisations de la représentation des connaissances. Enfin, des questions importantes comme ľanalyse et le contrǒle ?expressions sont traitées.  相似文献   
66.
Studies were performed to determine the effects of sorbic hydroxamic acid (SHA) and mastic oil–ethanol (ME) or water‐ethanol (WE) emitters on the growth of Bacillus cereus in high‐moisture, high‐pH (~8.9) English‐style crumpets stored at ambient temperature (25C). While SHA (3000 p.p.m.), alone or in combination with ME emitters, was effective in inhibiting the growth of B. cereus for 14 days in high‐pH crumpets, only SHA formulated crumpets packaged in air had acceptable sensory scores at the end of storage. However, ME emitters alone were ineffective in controlling the growth of this pathogen. This lack of inhibition in crumpets was attributed to the poor absorption of mastic volatiles from the package headspace into the food matrix. Whatever the reason, these preliminary studies showed that SHA has the potential to control the growth of B. cereus in high‐moisture, high‐pH crumpets without compromising product quality.  相似文献   
67.
The reactions with alkali of the disulphide bonds and the primary amino side–chains in wool have been investigated. Formation of dehydroalamine has been postulated and it has been conclusively identified in an alkali–treated, cystine–containing polypeptide. The mechanism of degradation of cystine in such a peptide has been further investigated and it has been shown that cysteine residues, produced from cystine during degradation, are also capable of degrading further to dehydroalanyl residues. The dehydroalanyl residues so produced are capable of reacting not only with other residues to form LAN and LAL, but also with other species present in the alkaline medium. The influence of amines on the cold setting of wool fibres with thioglycollates and on the dyeability of wool has been studied. Mechanisms are postulated to explain these effects.  相似文献   
68.
ABSTRACT: The usual Third World pattern of urbanization does not apply to Chinese urban development. China has not experienced the overurbanization and imbalances that often accompany growth in cities elsewhere. China's unique urban pattern results from national policies aimed at shaping urban growth. When those policies were relaxed, there was a tendency for Chinese urban patterns to conform with those of other Third World nations. Periods of less control corresponded with periods of experimentation with elements of a market economy and China's entry in the world economy. The authors explore the debate between urban bias theory and world system theory by considering how global structures and processes interact with local or national policies.  相似文献   
69.
Defatted soy flour containing low levels of added hydrocolloid (either sodium alginate or methylcellulose) was thermoextruded in a laboratory single-screw extruder, and the effect of operating parameters on selected textural properties (maximum peak force, determined in an Ottawa Measuring (OTMS) cell, and chewiness) and physical properties (bulk density and water absorption capacity) were studied. Adding sodium alginate generally increased OTMS peak force, chewiness and water absorption capacity and increased bulk density. Extruding at a feed moisture content of 22% w/w resulted in the best properties, regardless of the levels of other independent variables. Maximum force and chewiness were positively correlated while bulk density and water absorption capacity were negatively correlated to each other.  相似文献   
70.
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