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   268篇
  免费   5篇
综合类   2篇
化学工业   37篇
金属工艺   4篇
机械仪表   6篇
建筑科学   8篇
矿业工程   1篇
能源动力   1篇
轻工业   33篇
水利工程   1篇
石油天然气   2篇
无线电   7篇
一般工业技术   16篇
冶金工业   120篇
原子能技术   2篇
自动化技术   33篇
  2021年   2篇
  2020年   5篇
  2019年   2篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2015年   5篇
  2013年   10篇
  2012年   6篇
  2011年   9篇
  2010年   6篇
  2009年   11篇
  2008年   10篇
  2007年   10篇
  2006年   9篇
  2005年   5篇
  2004年   6篇
  2003年   9篇
  2002年   8篇
  2001年   5篇
  2000年   9篇
  1999年   5篇
  1998年   10篇
  1997年   4篇
  1996年   8篇
  1995年   6篇
  1994年   6篇
  1993年   14篇
  1992年   5篇
  1991年   5篇
  1990年   2篇
  1989年   6篇
  1988年   2篇
  1987年   6篇
  1986年   7篇
  1985年   2篇
  1984年   5篇
  1983年   3篇
  1982年   6篇
  1981年   5篇
  1980年   2篇
  1979年   2篇
  1978年   3篇
  1977年   4篇
  1975年   2篇
  1974年   2篇
  1968年   2篇
  1964年   3篇
  1961年   2篇
  1957年   1篇
排序方式: 共有273条查询结果,搜索用时 0 毫秒
41.
115 rape victims (aged 15–71 yrs) were examined at 2 wks and at 1, 2, 4, 8, and 12 mo after the assault. A matched control group of 87 nonvictims was seen at the same intervals. To control for the effects of repeated testing, 3 additional groups of 22–26 victims were assessed only once at 2, 4, or 8 mo postrape. All Ss completed the Beck Depression Inventory and the Hamilton Psychiatric Rating Scale for Depression. Depressive symptoms were significantly higher in victims of rape than in nonvictim controls following the assault. By 4 mo postrape, depressive symptoms in the victim group had diminished to the level shown by the nonvictim control group. Results from the single-testing victim groups indicated that repeated assessment affected the self-report measure, but not the interviewer-rated measure. Variables reflecting pre-rape functioning were more predictive of continued problems with depressive symptoms than were demographic variables or variables associated with the rape and its aftermath. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
42.
One of the assumptions underlying the F test of parallelism of 2 or more regression lines is that the within-group residual variances are homogeneous. In the present study, a 2-group Monte Carlo investigation examined the effect of violating this assumption for F, a large-sample chi-square approximation (U?), and an approximate F test (F*). In terms of Type I error probabilities, the standard F test performed acceptably well as long as sample sizes were equal. This was not true when sample sizes were unequal, with F* proving to be clearly superior. The pattern of results parallel exactly what is known about the robustness of the F test when testing for mean differences in the presence of unequal variances. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
43.
This paper describes the interactive multimedia injection molding tutor developed at the University of Massachusetts Amherst. The purpose of the tutor is to use visually stimulating animations in order to enable the user, a student or anyone not familiar with the process of injection molding, in understanding the relationship between part design and the ease or difficulty of producing the part. Preliminary evaluations indicate that the tutor can be successful in achieving these objectives.  相似文献   
44.
This article explores how, following bereavement, textile artwork may be able to make a connection with the viewer and allow a progression of their work of mourning. It takes an interdisciplinary approach, drawing from the literature of psychoanalytical theory, affectivity, and textile thinking to understand the importance of cloth as artwork in the grieving process. The article draws on the practice-based textile research of the author which, together with responses to the artworks made, discusses the way viewers can make an emotional investment in textile artwork and considers the concept of exhibitionary affect to increase the emotional connection of the viewer to the work.  相似文献   
45.
Response time information is important in most applications involving transient temperature measurements with thermocouples. Traditionally, the response time of a thermocouple is measured in a laboratory at a reference condition. The laboratory response time information is useful for comparative evaluation of thermocouples but may have little relationship with the response time for the sensor in service. This is because of the effects of installation and process operating conditions on response time.

A method has been developed and validated for response time testing of thermocouples as installed in an operating process. The details are reviewed in this paper. The method is referred to as the Loop Current Step Response Test. The test involves an internal heating of the thermocouple by applying an electrical current to the thermocouple extension wires. The current is then terminated and the thermocouple output is monitored as it returns to ambient temperature. This transient output is analyzed to identify the time constant of the thermocouple. A mathematical transformation is used to convert the internal transient data to the response of the thermocouple for an external temperature perturbation.  相似文献   

46.
The present study examined whether school-age children show risk compensation and engage in greater risk taking when wearing safety gear compared to when not doing so when running an obstacle course containing hazards that could lead to physical injury. Because sensation seeking has been shown to influence risk taking, this child attribute was also assessed and related to risk compensation. Children 7-12 years of age were videotaped navigating the obstacle course twice, once wearing safety gear and once without safety gear, with reverse directions used to minimize possible practice effects. The time it took the child to run through the course and the number of reckless behaviors (e.g., falls, trips, bumping into things) that the child made while running the course were compared for the gear and no-gear conditions. Results indicated that children went more quickly and behaved more recklessly when wearing safety gear than when not wearing gear, providing evidence of risk compensation. Moreover, those high in sensation seeking showed greater risk compensation compared with other children. Implications for childhood injury prevention are discussed.  相似文献   
47.
Over the past several years, students, academic program faculty, and internship training directors have become increasingly concerned about the inequity between the demand for predoctoral internship slots and the limited supply of those placements. This article presents data from the 1999 Association of Psychology Postdoctoral and Internship Centers' (APPIC) Match, along with the results of 2 studies conducted by the authors. Results indicate that the number of internship positions available in the U.S. and Canada may be nearly balanced with the number of first-time internship applicants and that the current imbalance may result, in large part, from a carryover of unplaced applicants from previous selection processes. Furthermore, approximately ? of unmatched applicants are able to find internship positions subsequent to the conclusion of the matching process, although many of these positions are in non-American Psychological Association-accredited and non-APPIC-member programs. Implications of these findings for the profession and for student applicants are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
48.
Microwave energy can be used to polymerize embedding polymers used for light and electron microscopy, providing novel and ultrarapid processing methods to accomplish cell and tissue embedments. These quick methods steadily show promise for diagnosis of disease where rapid methods can be crucial. This review is intended to answer some of the questions microscopists may have in attempting to utilize such microwave embedding procedures and to provide a comparison of results using divergent Medcast and LR White.  相似文献   
49.
We have recently introduced several important improvements in the measurement of distillation curves for complex fluids. The modifications include a composition-explicit data channel for each distillate fraction (for both qualitative and quantitative analysis) and corrosivity assessment of each distillate fraction. The composition-explicit information is achieved with a new sampling approach that allows precise qualitative as well as quantitative analyses of each fraction, on the fly. We have applied the new method to a variety of fluids, including simple n-alkanes, rocket propellant, gasoline, jet fuels, and a hydrocarbon fluid made corrosive with dissolved hydrogen sulfide. In the current contribution, we present the application of the advanced distillation curve method to two samples of crude oil. A primary motivation behind the work is to precisely measure the distillation curves of these oils using our advanced distillation apparatus; these low uncertainty measurements of true thermodynamic state points can be used for equation of state development and differentiation of crude oil samples. Then, the information content of each distillation was extended much further by use of the composition-explicit data channel: gas chromatography–mass spectrometry (GC–MS), infrared spectrophotometry (IR), gas chromatography with sulfur chemiluminescence detection (GC–SCD), and the copper strip corrosion test (CSCT) were used for each distillate volume fraction sampled. Consequently, for each volume fraction of crude oil distillate sampled, we can address the composition, quantitate the total sulfur content, and measure the corrosivity.  相似文献   
50.
Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants over the last three decades, and are now ubiquitous in the marine environment. While the harmful effects of PBDEs on the abnormal development and reproductive impairment in mammals and fish are well documented, the effects on marine invertebrates remain virtually unknown. Using three model intertidal species accross three phyla, including the polychaete Hydroides elegans (Phylum Annelida), the gastropod Crepidula onyx (Phylum Mollusca), and the barnacle Balanus amphitrite (Phylum Arthopoda), this study demonstrated that (a) chronic exposure to BDE-47 (at spiking concentrations up to 1000 ng L(-1)) throughout the entire larval stage did not affect settlement, development or growth of all three species per se, despite bioaccumulation was clearly evident (measured body burden ranging from approximately 7000 to 13?000 ng BDE-47 g(-1) lipid), and (b) BDE-47, at measured concentrations of 15 and 113 ng g(-1) lipid, reduced the bacterial abundance in biofilms and resulted in a concomitant change in larval settlement pattern of all the model intertidal species across three phyla.  相似文献   
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