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排序方式: 共有1791条查询结果,搜索用时 15 毫秒
91.
RK Valicenti LG Gomella M Ismail SG Mullholland RO Petersen BW Corn 《Canadian Metallurgical Quarterly》1998,82(10):1909-1914
BACKGROUND: The authors evaluated the effect of postoperative radiation therapy on freedom from biochemical failure (bNED) in men with prostate carcinoma who had pathologic seminal vesicle invasion after radical prostatectomy and negative pelvic lymph node dissection (pT3cN0). METHODS: Between 1989 and 1995, 375 men underwent radical prostatectomy at Thomas Jefferson University Hospital. Fifty-three men (13%) had pT3cN0 prostate carcinoma and were the subject of this analysis. Men in whom prostate specific antigen (PSA) could not be detected were deemed free of biochemical failure. RESULTS: Of the 53 men with pT3cN0 prostate carcinoma, 18 had an elevated PSA immediately after surgery and received salvage radiation therapy (RT). The 3-year bNED rate for this group was only 38%. At 3 months, PSA could not be detected in the other 35 men. Fifteen of those 35 men underwent early adjuvant RT, and the other 20 were observed for biochemical failure. The 3-year bNED rate for the 15 patients treated with immediate adjuvant RT was 86%, compared with 48% for the 20 men who were observed (P = 0.01). CONCLUSIONS: These data suggest that early adjuvant RT for men with pT3cN0 prostate carcinoma and no detectable PSA postoperatively reduces the likelihood of future biochemical failure. Men with pT3cN0 prostate carcinoma and a persistently elevated postoperative PSA level are less likely to benefit from RT and should be considered for systemic therapy. 相似文献
92.
Evenson K. Jennings D. Petersen F. Mucha J. Jimenez J. Charlton R. Howard C. 《Quantum Electronics, IEEE Journal of》1977,13(6):442-444
Optically pumped FIR lasers are currently in use in both frequency metrology and laser magnetic resonance spectroscopy programs in the NBS Boulder labs. The laser for use in frequency metrology is a CW 71 μm methyl alcohol waveguide laser with over 100 mW output for frequency synthesis. Another laser with an intracavity absorption cell for laser spectroscopy has been constructed and is nearly transversely pumped. The metrology technique used to measure the frequency of these lasers is briefly reviewed and a unique power meter is described. 相似文献
93.
A thin-film composite reverse osmosis (RO) membrane has been developed that provides excellent performance when used in single-pass seawater systems. This membrane, designated FT-30, gives superior performance in such areas as flux, salt rejection, chemical stability, and microbiological resistance. In addition, it is resistant to some oxidizing disinfectant agents, although it is not fully resistant to chlorine; elements fabricated from the membrane have shown damage after 2,000 to 2,500 hours exposure to seawater at 0.5 milligrams per liter (mg/l) active chlorine. It appears that the membrane can operate continuously at active chlorine concentrations below 0.2 mg/l.Several long-term studies were carried out at the OWRT Wrightsville Beach Test Facilities. In actual trials in seawater systems, salt rejections as high as 99.5 percent and fluxes of 23 gfd have been obtained when tested at 800 psi and 25°C. Some of the elements have been in continuous operation for over 4, 000 hours with no deterioration in salt rejection and with only the normal flux decline usually associated with compaction and scaling. Other elements have been installed in small seawater systems with normal intermittant use for almost two years with no serious loss in performance. 相似文献
94.
Clifford C. Petersen 《IIE Transactions》1974,6(2):143-150
A heuristic algorithm for solving capital budgeting problems is described. The algorithm proceeds from an initial solution, obtained with the use of ranking procedures, and progressively improves the solution through exchange operations. Computational experience in solving a set of 30-variable, 5-constraint problems is described and the approach to optimal values with increasing computation time is shown. The results show considerable time advantage over 0-1 implicit enumeration techniques. In only two of twenty-eight problems were the solutions nonoptimal, and in these two cases the objective function values for the heuristic solutions were within 0.5 percent of those for the optimal solutions. A brief investigation was conducted on larger problems (60 variables, 5 constraints); the time advantage is even greater on problems of that size. Details of the problems and their optimal solutions are available to interested readers upon request to the author. 相似文献
95.
Major process accidents have typically occurred not through a single failure, but through a combination of events, some of which had contributors from past actions and failures (latent or unrevealed failures). People are integral and key features of business systems; therefore systems, tools, and equipment should be designed with the potential capabilities and limitations of people in mind. This paper demonstrates the benefits of using human factors approaches to improve system safety and reliability. Practical examples from past experience are quoted and a framework for human error prediction is described. Guidance is given on the practicalities of deriving recommendations from these types of studies. 相似文献
96.
Imaging through scattering materials is an important research area that is generally limited to medical diagnostic applications. Published techniques typically use a method of time- or coherence-gating of ballistic photons that separates these early photons in order to acquire an image without the large background created by the later-arriving diffuse light. Because of the limited number of ballistic photons and the typically low signal-to-noise ratios of these schemes, a large number of averages or scans is necessary. If the desired image is changing rapidly, however, single images of this transient are required. We have therefore evaluated a two-dimensional, single-shot method that can be used for imaging rapid transients in scattering environments. 相似文献
97.
98.
The N-acylethanolamine phospholipids (NAPE) are precursors for N-acylethanolamines (NAE), including anandamide (20∶4-NAE), which is a ligand for the cannabinoid receptors. Previously, NAPE
were believed to be found only in injured tissue, e.g., after neurodegenerative insults. Neuronal injury may occur in response
to seizure activity. Therefore, we investigated the effect of pentylenetetrazol (PTZ)-induced seizures in PTZ-kindled mice
on the level of NAPE in the brain. Male NMRI mice were kindled with PTZ injections 3 times/wk, thereby developing clonic seizures
in response to PTZ. Mice were killed within 30 min after the clonic seizure on the test day (12th injection) and the brains
were collected. Eight species of NAPE were analyzed as the glycerophospho-N-acylethanolamines by high-performance liquid chromatography-coupled electrospray ionization mass spectrometry. No effect
of the PTZ kindling on the NAPE levels in murine brains was observed. Total NAPE in control mice cortex (n=4) was 16.4±3.0 μmol/g wet weight of which 20∶4-NAPE accounted for 3.6 mol%, and the major species was 16∶0-NAPE, accounting
for 52.1 mol%. Determination of the activity of NAPE-hydrolyzing phospholipase D and of N-acyltransferase in brain membrane preparations from adult and 3-d-old mice revealed an enzyme pattern in the adult mice that
was favorable for NAE accumulation as opposed to NAPE accumulation. Thus, there was no difference in NAPE levels; at present,
however, this does not exclude that NAE may accumulate during seizure. 相似文献
99.
L.?BaillieEmail author D.?Benyon C.?Macaulay M.?G.?Petersen 《Cognition, Technology & Work》2003,5(1):33-43
This paper argues that the current involvement of end users in the design of technological artefacts is too superficial.
It is common to involve people in requirements generation, but rarely in product inception or design. A study is reported
involving five households in central Scotland, who were each visited on three occasions, using a new investigative framework.
Illustrative examples are provided of the strengths and weaknesses of the methods used. Despite the latter, it is demonstrated
that the general public can both generate and critique design ideas and that valuable contributions to understanding people's
relationships with technologies can be expected both from children and from the elderly.
Electronic Publication 相似文献
100.