首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   84篇
  免费   0篇
电工技术   1篇
化学工业   4篇
金属工艺   1篇
能源动力   1篇
轻工业   4篇
无线电   14篇
一般工业技术   3篇
冶金工业   51篇
自动化技术   5篇
  2021年   1篇
  2020年   1篇
  2013年   3篇
  2012年   2篇
  2011年   1篇
  2010年   3篇
  2009年   3篇
  2008年   1篇
  2007年   2篇
  2006年   3篇
  2005年   3篇
  2004年   4篇
  2003年   2篇
  2001年   3篇
  2000年   2篇
  1998年   7篇
  1997年   3篇
  1996年   2篇
  1994年   2篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   7篇
  1989年   2篇
  1988年   2篇
  1987年   4篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   1篇
  1977年   2篇
  1975年   1篇
  1974年   1篇
  1972年   3篇
  1970年   1篇
  1969年   2篇
  1966年   1篇
排序方式: 共有84条查询结果,搜索用时 31 毫秒
11.
12.
Describes the equipment and general operation of the Asia Pacific Cable Network (APCN). Because of its uniqueness to APCN additional detail regarding the powering system and its restoration have been supplied. Once operational in late 1996, APCN will interconnect countries in a region of the world that is experiencing rapid growth in demand for telecommunication services. With trans-Pacific and other interregional networks such as the TPC-5 Cable Network and the FLAG network going into service in 1996 and 1997, APCN will not only serve as a regional network, but as a feeder network to these networks, providing connectivity to other parts of the world. APCN will play an important role as another network in the ever growing global undersea communications network  相似文献   
13.
Many species of bacteria pathogenic to humans, such as Legionella, are thought to have evolved in association with amoebal hosts. Several novel unculturable bacteria related to Legionella have also been found in amoebae, a few of which have been thought to be causes of nosocomial infections in humans. Because amoebae can be found in cooling towers, we wanted to know whether cooling tower environments might enhance the association between amoebae and bacterial pathogens of amoebae in order to identify potential "hot spots" for emerging human pathogens. To compare occurrence of infected amoebae in natural environments with those in cooling towers, 40 natural aquatic environments and 40 cooling tower samples were examined. Logistic regression analysis determined variables that were significant predictors of the occurrence of infected amoebae, which were found in 22 of 40 cooling tower samples but in only 3 of the 40 natural samples. An odds ratio showed that it is over 16 times more likely to encounter infected amoebae in cooling towers than in natural environments. Environmental data from cooling towers and natural habitats combined revealed dissolved organic carbon (DOC) and pH were predictors of the occurrence of the pathogens, however, when cooling tower data alone were analyzed, no variables accounted for the occurrence. Several bacteria have novel rRNA sequences, and most strains were not culturable outside of amoebae. Such pathogens of amoebae may spread to the environment via aerosols from cooling towers. Studies of emerging infectious diseases should strongly consider cooling towers as a source of amoeba-associated pathogens.  相似文献   
14.
Comments on the original article Personality traits and the classification of mental Disorders: Toward a more complete integration in DSM–5 and an empirical model of psychopathology by Robert F. Krueger and Nicholas R. Eaton (see record 2010-13810-003). This article develops the larger theme that the fundamental quantitatively developed architecture of personality provides a sound base for classifying all areas of psychopathology and, more specifically, should underlie the current effort to revise the classification of personality disorders (PDs) in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). My commentary is organized around what I perceive to be four significant problems with the proposed change to a trait-based system: (1) unfamiliarity to clinicians (and possibly unfeasibility), (2) lack of clinical utility, (3) the preliminary quality of the science upon which the proposed change is based, and (4) harmful effects on the diagnosis of borderline personality disorder (BPD). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
15.
In order to improve understanding of how aluminum contributes in non‐ideal explosive mixtures, cast‐cured formulations have been analyzed in a series of cylinder tests and plate‐pushing experiments. This study describes the contribution of 15 % aluminum (median size of 3.2 μm) vs. lithium fluoride (an inert substitute for aluminum; <5 μm) in cast‐cured HMX formulations in different temporal regimes. Small cylinder tests were performed to analyze the detonation and wall velocities (1–20 μs) for these formulations. Near‐field blast effects of 58 mm diameter spherical charges were measured at 152 mm and 254 mm using steel plate acceleration. Pressure measurements at 1.52 m gave information about free‐field pressure at several milliseconds. While the observed detonation velocities for all formulations were within uncertainty, significantly higher cylinder wall velocities, plate velocities, and pressures were observed for the aluminum formulations at ≥2 μs. Additionally, hydrocode calculations were performed to determine how non‐ideal behavior affected the plate test results. Collectively, this work gives a clearer picture of how aluminum contributes to detonation on timescales from 1 μs to about 2 ms, and how the post‐detonation energy release contributes to wall velocities and blast effects. The experiments indicate that significant aluminum reactions occur after the CJ plane, and continue to contribute to expansion at late times.  相似文献   
16.
Reports an error in "What counts in the development of young children's number knowledge" by Susan C. Levine, Linda Whealton Suriyakham, Meredith L. Rowe, Janellen Huttenlocher and Elizabeth A. Gunderson (Developmental Psychology, 2010[Sep], Vol 46[5], 1309-1319). A coding error resulted in incorrect item-level data being reported on the point-to-x task (not the children‘s overall performance on this task) in Table 2 and in the section of the Results headed Point-to-X Task Performance (second column, p. 1314). In the first paragraph in the section, the correct average score for knowledge of cardinal meanings of the number words. In the second paragraph in the section, there is an example illustrating children’s greater performance on items involving a target and a distractor that were one digit apart. An additional adjustment in the second paragraph involves the finding that children performed better when at least one of two choice sets was a small number (1–3) than when both choice sets were greater than or equal to 4. More information for the corrections and the corrected table are given in the erratum. (The following abstract of the original article appeared in record 2010-17955-026.) Prior studies indicate that children vary widely in their mathematical knowledge by the time they enter preschool and that this variation predicts levels of achievement in elementary school. In a longitudinal study of a diverse sample of 44 preschool children, we examined the extent to which their understanding of the cardinal meanings of the number words (e.g., knowing that the word “four” refers to sets with 4 items) is predicted by the “number talk” they hear from their primary caregiver in the early home environment. Results from 5 visits showed substantial variation in parents' number talk to children between the ages of 14 and 30 months. Moreover, this variation predicted children's knowledge of the cardinal meanings of number words at 46 months, even when socioeconomic status and other measures of parent and child talk were controlled. These findings suggest that encouraging parents to talk about number with their toddlers, and providing them with effective ways to do so, may positively impact children's school achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
17.
The phase partitioning of additives in polymer blends has a large impact on the performance of the blend. Therefore, it is necessary to be able to quantify the level of the additives in each phase. A 1H–NMR method is presented to determine the partitioning of additives between the rubber and rigid phases of a high‐impact polystyrene (HIPS) material. In one case, a HIPS material was modified with 2,6‐di‐tert‐butyl‐4‐methyl‐phenol (Ionol, CAS# 128‐37‐OMF) as a stabilizer for both phases. HIPS materials with varying levels of Ionol were melt‐blended by extrusion and the total level of additives was determined analytically for these standard materials. The 1H–NMR method was used to determine the level of Ionol in the poly(butadiene) rubber phase. The Ionol was found to preferentially partition into the rubber phase with a partition coefficient of about 2. A second example of the same concept, instead utilizing 13C–NMR, involved the analysis of the partition coefficient for both Tinuvin P and Tinuvin 770 (CAS# 2440‐22‐4 and 52829‐07‐9), partitioning between the rigid and rubber phases of an ethylene–propylene–diene‐modified (EPDM) toughened styrene–ran–acrylonitrile (SAN) copolymer. The partition coefficient was determined to be 0.5 for Tinuvin P and 1.3 for Tinuvin 770. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1963–1970, 2001  相似文献   
18.
Intraoperative radiation therapy (IORT) in its broadest sense refers to the delivery of irradiation at the time of an operation. This article will discusses the rationale for and results of both intraoperative electron radiation therapy and intraoperative high dose rate brachytherapy when used in conjunction with surgical exploration and resection and external beam radiation therapy and chemotherapy. Both IORT methods evolved with similar philosophies as an attempt to achieve higher effective doses of irradiation while dose limiting structures are surgically displaced.  相似文献   
19.
This study examined the relationships of the Schedule for Nonadaptive and Adaptive Personality (SNAP) model of personality to 4 targeted personality disorders (PDs) in a large multisite sample of patients. Data were examined from 529 patients, who were assigned 1 of 5 primary diagnoses: borderline, schizotypal, avoidant, and obsessive-compulsive PDs and major depression without PD. Patients were administered the SNAP questionnaire and results were compared among diagnostic groups and between patient groups and nonclinical norms. Results indicated that the dimensions of the model appear to have considerable promise in differentiating normal from abnormal personality, particularly in the propensity of individuals with PDs to manifest negative affects and interpersonal detachment. Furthermore, the model appeared to successfully distinguish specific PDs, a property that represents a particular challenge for dimensional models of personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号