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   164篇
  免费   0篇
电工技术   2篇
化学工业   21篇
金属工艺   3篇
机械仪表   2篇
建筑科学   6篇
矿业工程   1篇
轻工业   39篇
水利工程   1篇
石油天然气   2篇
无线电   12篇
一般工业技术   15篇
冶金工业   46篇
自动化技术   14篇
  2023年   1篇
  2022年   3篇
  2021年   2篇
  2018年   1篇
  2014年   1篇
  2013年   4篇
  2012年   3篇
  2011年   7篇
  2010年   10篇
  2009年   2篇
  2008年   6篇
  2007年   4篇
  2006年   10篇
  2005年   4篇
  2004年   4篇
  2003年   1篇
  2002年   2篇
  2001年   5篇
  2000年   4篇
  1999年   1篇
  1998年   13篇
  1997年   12篇
  1996年   10篇
  1995年   5篇
  1994年   3篇
  1993年   1篇
  1992年   1篇
  1991年   5篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   3篇
  1984年   4篇
  1983年   1篇
  1980年   3篇
  1978年   1篇
  1977年   4篇
  1976年   3篇
  1974年   2篇
  1973年   1篇
  1971年   3篇
  1970年   3篇
  1969年   2篇
  1968年   2篇
  1961年   1篇
排序方式: 共有164条查询结果,搜索用时 0 毫秒
81.
82.
Sparfloxacin, a new orally administered fluoroquinolone, was tested against 14,182 clinical strains isolated (generally blood stream and respiratory tract cultures) at nearly 200 hospitals in the United States (USA) and Canada. Sparfloxacin activity was compared with 13 other compounds by Etest (AB BIODISK, Solna, Sweden), broth microdilution, or a standardized disk diffusion method. Using the Food and Drug Administration/product package insert MIC breakpoint for sparfloxacin susceptibility (< or = 0.5 microgram/ml), 94% of Streptococcus pneumoniae (2666 isolates) and 89% of the other streptococci (554 isolates) were susceptible. However, at < or = 1 microgram/ml (the breakpoint for all nonstreptococcal species) sparfloxacin susceptibility rates increased to 100% and 98%, respectively, for the two groups of streptococci. Only 50% and 65% of pneumococci were susceptible to ciprofloxacin (MIC90, 3 micrograms/ml) and penicillin (MIC90, 1.5 micrograms/ml), respectively. Although there were significant differences between regions in the USA in the frequency of penicillin-resistant pneumococcal strains, results indicate that the overall sparfloxacin MIC90 was uniformly at 0.5 microgram/ml. Nearly all (> or = 99%) Haemophilus species and Moraxella catarrhalis, including those harboring beta-lactamases, were susceptible to sparfloxacin, ciprofloxacin, and amoxicillin/clavulanic acid. Only cefprozil and macrolides demonstrated lower potency and spectrum against these two species. Sparfloxacin was active against oxacillin-susceptible Staphylococcus aureus (96 to 97%), Klebsiella spp. (95%), and other tested enteric bacilli (93%). Comparison between broth microdilution MIC and disk diffusion interpretive results for M. catarrhalis, Staphylococcus aureus, and the Enterobacteriaceae showed an absolute intermethod categorical agreement of > 95% using current sparfloxacin breakpoints, in contrast to those of cefpodoxime for S. aureus where a conspicuous discord (98% versus 59%) between methods was discovered. These results demonstrate that sparfloxacin possesses sufficient in vitro activity and spectrum versus pathogens that cause respiratory tract infections (indications), especially strains resistant to other drug classes such as the earlier fluoroquinolones, oral cephalosporins, macrolides, and amoxicillin/clavulanic acid. The sparfloxacin susceptibility breakpoint for streptococci may require modification (< or = 1 microgram/ml) based on the MIC population analysis presented here. A modal MIC (0.38 to 0.5 microgram/ml) was observed at the current breakpoint. Regardless, sparfloxacin inhibited 89% (nonpneumococcal Streptococcus spp.) to 100% (Haemophilus spp., M. catarrhalis) of the isolates tested with a median activity of 97% against indicated species.  相似文献   
83.
To exploit larger amounts of instruction level parallelism, processors are being built with wider issue widths and larger numbers of functional units. Instruction fetch rate must also be increased in order to effectively exploit the performance potential of such processors. Block-structured ISAs provide an effective means of increasing the instruction fetch rate. We define an optimization, called block enlargement, that can be applied to a block-structured ISA to increase the instruction fetch rate of a processor that implements that ISA. We have constructed a compiler that generates block-structured ISA code, and a simulator that models the execution of that code on a block-structured ISA processor. We show that for the SPECint95 benchmarks, the block-structured ISA improves the performance of an aggressive wide issue, dynamically scheduled processor by 15% while using simpler microarchitectural mechanisms to support wide issue and dynamic scheduling.  相似文献   
84.
OBJECTIVE: To determine the role of weight loss in the treatment of idiopathic intracranial hypertension (IIH) in obese women. METHODS: Chart review of 250 patients with suspected IIH revealed 58 women who met our criteria, did not undergo early surgical intervention, and had adequate documentation of visual status, papilledema, and weight at the baseline evaluation and at 6 months or longer. Patients were divided into two groups based on whether weight loss > or = 2.5 kg occurred during any 3-month interval. Papilledema grade, visual acuity, and visual field grade at 6 months or longer and the time to improve each were recorded. RESULTS: Mean time in months to improve one grade for papilledema and visual field in one eye was 4.0 versus 6.7 (p = 0.013) and 4.6 versus 12.2 (p = 0.032), respectively, for the 38 patients with weight loss compared with the 20 patients with no weight loss. Papilledema resolved in 28/38 with weight loss (mean, 7.6 months) and 8/20 without weight loss (mean, 10.2 months; p = 0.352). There were no differences in final visual acuity or visual field between the two groups, but the papilledema grade was slightly better in the worst eye in each patient at baseline in the weight loss group (p = 0.03). CONCLUSIONS: Weight reduction is associated with more rapid recovery of both papilledema and visual field dysfunction in patients with IIH compared with those who do not lose weight.  相似文献   
85.
The strength of freeze-bonds in thin saline ice has been investigated through two series (in 2008 and 2009) of experiments in the Hamburg Ship Model Basin (HSVA) as a function of the normal confinement (σ), the submersion time (Δt) and the initial ice temperature (Ti). The freeze-bonds were mostly formed in a submerged state, but some were also formed in air. The experimental set-up was improved in the 2009 experiments. In 2008 a ductile-like failure mode dominated (78%), whereas in 2009 the brittle-like dominated (93%). We suggest that this is a combined ice and test set-up effect. The 2009 experimental procedures allowed for careful sample handling giving higher strength and it was softer. Both these things should provoke a more brittle-like force-time response. The average freeze-bond strength in brittle-like samples was around 9 kPa while in ductile-like samples was around 2 kPa. The maximum freeze-bonds strength were measured for short submersion times, from 1 to 20 min, and reached a maximum value of 30 kPa.A Mohr-Coulomb like failure model was found appropriate to represent the freeze-bond shear strength as function of the normal confinement. Saline freeze-bonds in saline water had cohesion/friction angle around 4 and 1.4 kPa/25° for the brittle- and ductile-like samples respectively, which fitted well with previously published data.A bell-shape dependence for τc vs. Δt was found, which agreed with the predictions by Shafrova and Høyland (2007). We suggest that this is essentially a freeze-bond porosity effect and propose three phases in time with subsequent cooling, heating and equilibrium to account for this trend. Qualitative experiments showed that the submersion time and the initial ice temperature were strongly coupled.To account for the connection between contact time, block dimensions and ice properties and the freeze-bond strength, dimensionless number were used. Fourier scaling was more appropriate than Froude scaling to scale freeze-bonds.The freeze-bonding made in air developed fast (in less than 30 s) when the ice was cold and dry, but no freeze-bonding occurred for the same contact times when the ice was warm and wet.  相似文献   
86.
We present the design and development of an organic package that is compatible with fully released RF microelectromechanical systems (MEMS). The multilayer organic package consists of a liquid-crystal polymer film to provide near hermetic cavities for MEMS. The stack is further built up using organic thin-film polyimide. To demonstrate the organic package, we have designed and implemented a 2-bit true-time delay X-band phase shifter using commercially available microelectromechanical switches. The packaged phase shifter has a measured insertion loss of 2.45 plusmn 0.12 dB/bit at 10 GHz. The worst case phase variation of the phase shifter at 10 GHz is measured to less than 5deg. We have also conducted temperature cycling (-65degC to 150degC) and 85/85 to qualify the packaging structures.  相似文献   
87.
Responds to the comments by T. van Strien (see record 2010-14873-003) on the current authors' original article, "Assessing yourself as an emotional eater: Mission impossible?" (see record 2009-20990-009). In her commentary, van Strien suggests that it may not be "impossible" to self assess for emotional eating, as a close inspection of the results of Evers et al reveals that their “no emotional eaters” did not show the typical stress response of eating less. This opens the possibility that the null findings of Evers et al may be simply explained by misclassification of “no emotional eaters” versus “emotional eaters” because of their use of median splits (a procedure notorious for possible misclassification of subjects into distinct groups). In this reply Evers et al address this criticism and other critiques of their study, and conclude that their results are in line with studies that have indicated that self-assessed emotional eating may reflect beliefs about emotional eating rather than one’s actual eating behavior when being emotional. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
88.
The electrical resistivity of high purity CaSi2, CaGe2, SrSi2, SrGe2, BaSi2 and BaGe2 was measured in the temperature range from 20°C to 800°C by a 4-point technique. CaSi2, CaGe2 and SrSi2 show metallic, SrGe2, BaSi2 and BaGe2 semiconducting behaviour. This difference can be explained by the change of the structure of the “anion”-sublattices and the change of the metal-distances in the metal-sublattices.  相似文献   
89.
Changes in spinal length were used to evaluate a new concept for an office chair. This so-called dynamic chair imparts passive forced motion to the seated subject. The passive forced motion is a rotary movement about an axis, perpendicular to the seat with amplitude of 0.6 degrees and a frequency of 0.08 Hz. Change of stature is assumed to provide a measure for spinal load. Eight subjects were measured in two situations: static (without motion) and dynamic. In both situations the same office tasks were performed and the duration of the sitting period was 1 h. To allow for the normal shrinkage curve the starting time was the same on each of the measurement days. The results indicated a significant difference: when sitting on the dynamic chair the average spinal length increased in comparison to the spinal length in the static chair, where average spinal length decreased. It was concluded that there is spinal distress relief due to the passive motion of the chair.  相似文献   
90.
Coaching has become an important managerial instrument of support. However, there is lack of research on its effectiveness. The authors conducted a quasi-experimental study to figure out whether coaching really leads to presupposed individual goals. Sixty managers of the federal government were divided in two groups: one group followed a coaching program, the other did not. Before the coaching program started (Time 1), self-efficacy beliefs and outcome expectancies were measured, linked to three central domains of functioning: setting one's own goals, acting in a balanced way and mindful living and working. Four months later (Time 2), the same variables were measured again. Results showed that the coached group scored significantly higher than the control group on two variables: outcome expectancies to act in a balanced way and self-efficacy beliefs to set one's own goals. Future examination might reveal whether coaching will also be effective among managers who work at different management levels, whether the effects found will be long-lasting, and whether subordinates experience differences in the way their manager functions before and after the coaching. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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