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81.
We present a case of sudden death in a 24-year-old, healthy white female who was physically active and participated in sports, including soccer. Two weeks prior to her death, an insurance physical examination revealed an abnormal electrocardiogram which demonstrated flipped T waves in the anterior leads. There was no other remarkable medical history. At autopsy, only one coronary ostium was demonstrated and it originated from the right aortic sinus. Approximately 0.8 cm from this right coronary artery (RCA) ostium, a left coronary artery (LCA) branched off the RCA at a 90-degree angle. The LCA had luminal diameter of 0.4 m but the LCA had a luminal diameter of only 0.1 cm. The LCA coursed anterior to the base of the pulmonary artery and down the anterior ventricular septum reflecting the usual course of the left anterior descending (LAD) coronary artery. The LCA and RCA paths appeared to merge or terminate at the anterior left ventricular myocardium which was discolored gray, a process that involved the inner and middle thirds of the myocardium. Based on the autopsy findings, we certified the cause of death as a probable arrhythmia due to myocardial fibrosis and dystrophic calcification resulting from complications of an anomalous hypoplastic left coronary artery. Anomalies of coronary arteries have been classified and studied at autopsy and by clinical angiography. Coronary artery anomalies can be divided into minor and major forms with major anomalies often resulting in cardiac dysfunction that may cause failure and death. Minor anomalies, in general, have no pathophysiological significance and are compatible with life. Minor anomalies include variations in number and location of coronary ostia. A single coronary ostia is exceedingly rare in hearts with no other congenital malformations. The prognostic significance can be unpredictable. A single coronary artery has the potential to be dangerous if obstructed at its main stem, or if it branches at an acute angle. Additionally, hypoplasia of one or more coronary arteries has been found to be associated with sudden death.  相似文献   
82.
McConnell  S. 《Computer》1998,31(5):100-102
Some people in the software development community think “process” is a four letter word. They think software processes are rigid, restrictive, and inefficient. They hold that the best way to run a project is to hire the best people you can, give them all the resources they ask for, and turn them loose to do what they do best. Sure, they say, there will be some amount of unproductive work is (also known as “thrashing”). After all, developers will make mistakes. But they will also be able to quickly and efficiently correct these mistakes at a cost that is less overall than the cost of processes. This point of view has intuitive appeal. At the beginning of a project, a focus on process certainly does take time away from productive work. If that trend were to continue throughout the project, it wouldn't make sense to spend much time on process. Software industry experience, however, has found that for projects that don't pay attention to establishing effective processes early are forced to slap them together late, when slapping them together takes more time and does less good. The article points out the problems caused by inattention to process, explains what happens when a project thrashes, and discusses the use of process versus creativity  相似文献   
83.
As an undergraduate computer science student, the author thought that the main reason to create new routines, instead of leaving all the code in one big routine, was to avoid duplicate code. This is undoubtedly the most popular reason for creating a routine, and it's a good one. Similar code in two routines is a warning sign. David Parnas says that if you use copy and paste while you're coding, you're probably committing a design error. Instead of copying code, move it into its own routine. Future modifications will be easier because you will need to modify the code in only one location. The code will be more reliable because you will have only one place in which to be sure that the code is correct. That is one good reason to create a routine, but it hardly makes a complete list. There are many additional reasons to create routines, and many of them are more important than avoiding duplicate code: reducing complexity; limiting effects of changes; hiding sequences; improving performance; hiding data structures; hiding global data; promoting code reuse; planning for a family of programs; improving readability; improving portability; isolating use of nonstandard language functions; and isolating complex operations  相似文献   
84.
Reviews the book, The social world of children learning to talk by B. Hart and T. Risley (1999). Betty Hart and Todd Risley's second book reporting the results of a longitudinal study of language development among children, ranging in age from 9 to 36 months, and their families. Rather than providing too little information from which to draw accurate conclusions, this second volume is a forceful and important follow-up to their earlier work, Meaningful differences in the everyday lives of young American children (Hart & Risley, 1996). This second volume focuses on the children themselves and the changes they make in social interactions and language production across the span of infancy, toddlerhood, and early preschool years. Learning to talk is an important volume in its own right, offering a detailed and rich picture of the relation between social and language development in young children. Serious students of language development, psychologists interested in early development, and practitioners or researchers interested in early development and intervention will all profit from this important contribution to our understanding of young children and their families. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
85.
Modern tools often separate the visual and physical aspects of operation, requiring users to manipulate an instrument while viewing the results indirectly on a display. This can pose usability challenges particularly in applications, such as laparoscopic surgery, that require a high degree of movement precision. Magnification used to augment the view and, theoretically, enable finer movements, may introduce other visual-motor disruptions due to the apparent speed of the visual motion on screen (i.e., motion scaling). In this research, we sought to better understand the effects of visual magnification on human movement performance and control in operating a tool via indirect vision. Ten adult participants manipulated a computer mouse to direct a pointer to targets on a display. Results (Experiment 1) showed that, despite increased motion scaling, magnification of the view on screen enabled higher precision control of the mouse pointer. However, the relative effectiveness of visual magnification ultimately depended on the scale of the physical movement, and more specifically the precision limits of the whole-hand grip afforded by the mouse. When the physical scale of the hand/mouse movement was reduced (Experiment 2), fine-precision control began to reach its limits, even at full magnification. The role of magnification can thus be understood as “amplifying” the particular skill level afforded by the effecting limb. These findings suggest a fruitful area for future research is the optimization of hand-control interfaces of tools to maximize movement precision. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
86.
We report on the application of confocal and multiphoton microscopic techniques for the evaluation of the latest generation of micro optical components. The optical emitting characteristics of arrays of matrix addressable GaN micrometer-sized light emitting diodes (micro-LEDs) have been measured using a commercial confocal microscope utilising the LEDs' own emission along with reflection confocal microscopy to determine the surface structure. Multiphoton induced luminescence from the 10-20-micron diameter emitters has also been used to examine the structure of the device and we compare this with electrically induced emission. In related work, the optical properties of micro lens arrays (10-100-micron diameter) fabricated in SiC, Sapphire, and Diamond have been determined using transmission confocal microscopy. Such optical microscopy techniques offer a simple, non-destructive method to determine the structure and performance of such novel devices.  相似文献   
87.
Composites in North America   总被引:1,自引:0,他引:1  
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88.
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90.
4-OH-2,3-trans-nonenal (HNE), a major aldehydic lipid peroxidation product, has been shown to cause cellular toxicities and has been linked to a number of pathophysiological processes including atherogenesis. Specifically, in vitro exposure of erythrocyte plasma membrane preparations to HNE resulted in the inhibition of membrane transport function and integrity. To characterize the nature of the inhibitory effects of HNE on plasma membrane regulatory mechanisms, we investigated its effects on substrate and calmodulin (CaM) stimulation on erythrocyte Ca2+ transport and (Ca2+ + Mg2+)-ATPase activities. Concentration-effect relationship analysis in erythrocyte membrane "ghosts" and inside-out vesicles (IOVs) yielded purely noncompetitive kinetics for Ca2+, ATP, and CaM activation of (Ca2+ + Mg2+)-ATPase and Ca2+ transport. Reductions of Vmax from direct addition of 0.1 mM HNE to the assay incubation mixtures ranged from 23 to 41%. Similarly, pretreatment with HNE of both membrane ghosts and IOVs resulted in a concentration-dependent inactivation of ATPase and transport activities without changes in affinity for Ca2+, ATP, or CaM. Conversely, pretreatment of CaM itself did not impair its ability to stimulate (Ca2+ + Mg2+)-ATPase activity threefold. Moreover, HNE-pretreated membranes exhibited unaltered acetylcholinesterase activity compared to sham-pretreated membranes. Together, these results suggest that HNE may structurally, and thus irreversibly, modify one or more functionally important sites on the transport protein itself.  相似文献   
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