全文获取类型
收费全文 | 869篇 |
免费 | 3篇 |
专业分类
化学工业 | 7篇 |
机械仪表 | 1篇 |
轻工业 | 41篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
冶金工业 | 818篇 |
自动化技术 | 3篇 |
出版年
2022年 | 1篇 |
2014年 | 4篇 |
2013年 | 2篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2003年 | 2篇 |
2002年 | 1篇 |
1999年 | 28篇 |
1998年 | 260篇 |
1997年 | 133篇 |
1996年 | 86篇 |
1995年 | 53篇 |
1994年 | 58篇 |
1993年 | 51篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 9篇 |
1985年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 10篇 |
1978年 | 1篇 |
1977年 | 24篇 |
1976年 | 61篇 |
1975年 | 2篇 |
1966年 | 1篇 |
1960年 | 1篇 |
1955年 | 3篇 |
排序方式: 共有872条查询结果,搜索用时 15 毫秒
61.
RT Ahvenainen EU Hurme M H?gg EH Skytt? EK Laurila 《Canadian Metallurgical Quarterly》1998,61(5):591-600
The present study was aimed to investigate the effects of indigestible dextrin and polydextrose, soluble dietary fibers with low molecular weight, on lipid metabolism and disaccharidase activities of intestinal mucosa in rats fed a high sucrose diet. Their effects were compared with those of well-known soluble fibers, pectin, and guar gum, and also with an insoluble fiber, cellulose. Dietary fibers added to diets at the 5% (w/w) level were alpha-cellulose, pectin, guar gum, indigestible dextrin, and polydextrose. Male Sprague-Dawley rats were given free access to test diets for 6 weeks. Body weight gain was the lowest in rats fed guar gum, the highest in rats fed cellulose, and in-between in rats fed other diets. Although guar gum, pectin, and indigestible feeding dextrin had lower plasma lipid values than cellulose feeding did, the differences were statistically insignificant. Liver triglyceride of the guar gum-fed group was about a third that of the cellulose-fed group, but although those of rats fed polydextrose, indigestible dextrin, and pectin were lower than that of cellulose, the differences were insignificant. Liver cholesterol and phospholipid concentrations were similar among groups. Daily fecal excretion of total lipid, cholesterol, and bile acids were highest in rats fed guar gum, followed by pectin-fed and cellulose-fed rats, and the lowest in rats fed indigestible dextrin and polydextrose. Jejunal sucrase activity was low in the order of guar-gum, polydextrose, indigestible dextrin, pectin, and cellulose. The results indicate that the hypolipidemic effect of soluble dietary fibers would be lessened with reduction in molecular weight, but that the lower sucrase activity by soluble fibers with low molecular weight might be beneficial for hypoglycemic effect. 相似文献
62.
EH Schemitsch DC Turchin GI Anderson RJ Byrick JB Mullen RR Richards 《Canadian Metallurgical Quarterly》1998,45(4):738-742
BACKGROUND: The potential to produce fat embolism may be important in determining the ideal method and timing of fracture treatment in patients with preexisting lung injury. METHODS: Four dogs underwent femoral and tibial canal reaming and pressurization. Blood gas samples were analyzed, and pulmonary arterial pressure was monitored at 1 and 72 hours. Animals were killed 72 hours postoperatively, and the lungs, kidneys, and brain were examined histologically and compared with equivalent specimens from four control dogs that had not undergone femoral and tibial canal reaming and pressurization. RESULTS: Postmortem, intravascular fat persisted for 72 hours after induction of pulmonary fat embolism. Mean PaO2 was unchanged from baseline at 72 hours after canal pressurization. Canal pressurization caused a sustained increase in pulmonary arterial pressure (p=0.02) for 1 hour after canal pressurization. The mean pulmonary edema score at 72 hours was 29+/-3. Only a scant polymorph infiltrate (zero to two polymorphs per high-power field) was present at any time. No hyaline membranes were seen at any time. The percentage area occupied by intravascular fat in the lungs was 0.0214+/-0.0058 at 72 hours. No signs of ischemia or inflammation were seen in either the cerebral or the renal specimens. CONCLUSION: This study is the first to show that intravascular fat persists in the lungs, kidneys, and brain for 72 hours after canal pressurization and, by itself, does not cause pathologic evidence of acute inflammation. 相似文献
63.
DA Spain TM Bergamini JF Hoffmann EH Carrillo JD Richardson 《Canadian Metallurgical Quarterly》1998,64(6):522-5; discussion 525-6
Multiple-trauma patients are at increased risk for deep venous thrombosis (DVT) but are also at increased risk of bleeding, and the use of heparin may be contraindicated. Sequential pneumatic compression devices (SCDs) are an alternative for DVT prophylaxis. However, lower extremity fracture or soft tissue injury may preclude their use. In these circumstances, foot pumps (FPs) are often substituted, yet little clinical data exist to support their use. We identified 184 consecutive high-risk trauma patients who received DVT prophylaxis with compression devices. We reviewed demographic data, mechanism of injury, Injury Severity Score, injury pattern, and method of prophylaxis. Generally, SCDs were preferred, but FPs were substituted in patients with lower extremity injuries. Occurrences of DVT or pulmonary embolism were also noted. Patients surviving less than 48 hours were excluded. SCDs were used in 118 patients (64%) and FPs in 66 patients (34%). There were no differences in age, Injury Severity Score, or presence of shock on admission. As expected, FP patients were more likely to have lower extremity fractures (65 vs 26%; P < 0.05) and were also more likely to have associated pelvic fracture (59 vs 25%; P < 0.05) and chest injury (61 vs 26%, P < 0.05). There was no difference in the incidence of head injury, although SCD patients had more severe head injuries (Glasgow Coma Score, 7.9 vs 10.5; P < 0.05). The overall incidence of DVT was 5.4 per cent (10 of 184), with no differences between the two groups (SCD 7% vs FP 3%). Three patients had a pulmonary embolism (FP, two; SCD, one), none of which were fatal. Compression devices provide adequate DVT prophylaxis with a low failure rate (3-8%) and no device-related complications. FPs appear to be a reasonable alternative in the high-risk trauma patient when lower extremity fractures precludes use of SCD. 相似文献
64.
The Ilizarov method has broad applications for the generation of bone and soft tissue via an external fixator composed of small pins, tensional wires, rings, hinges and distractors. The success of the technique depends on adherence to Ilizarov's principles of tension-stress phenomenon: preservation of the tissues' blood supply, frequent distraction in small increments, and full function of the extremity. 相似文献
65.
EH Uhlenhuth PE Alexander GM Dempsey W Jones BS Coleman AM Swiontek 《Canadian Metallurgical Quarterly》1998,47(1-3):183-190
Heart sounds produce an incessant noise during lung sounds recordings. This noise severely contaminates the breath sounds signal and interferes in the analysis of lung sounds. In this paper, the use of a wavelet transform domain filtering technique as an adaptive de-noising tool, implemented in lung sounds analysis, is presented. The multiresolution representations of the signal, produced by wavelet transform, are used for signal structure extraction. In addition, the use of hard thresholding in the wavelet transform domain results in a separation of the nonstationary part of the input signal (heart sounds) from the stationary one (lung sounds). Thus, the location of the heart sound noise (1st and 2nd heart sound peaks) is automatically detected, without requiring any noise reference signal. Experimental results have shown that the implementation of this wavelet-based filter in lung sound analysis results in an efficient reduction of the superimposed heart sound noise, producing an almost noise-free output signal. Due to its simplicity and its fast implementation the method can easily be used in clinical medicine. 相似文献
66.
67.
Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States 总被引:3,自引:0,他引:3
RC Lawrence CG Helmick FC Arnett RA Deyo DT Felson EH Giannini SP Heyse R Hirsch MC Hochberg GG Hunder MH Liang SR Pillemer VD Steen F Wolfe 《Canadian Metallurgical Quarterly》1998,41(5):778-799
OBJECTIVE: To provide a single source for the best available estimates of the national prevalence of arthritis in general and of selected musculoskeletal disorders (osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, the spondylarthropathies, systemic lupus erythematosus, scleroderma, polymyalgia rheumatica/giant cell arteritis, gout, fibromyalgia, and low back pain). METHODS: The National Arthritis Data Workgroup reviewed data from available surveys, such as the National Health and Nutrition Examination Survey series. For overall national estimates, we used surveys based on representative samples. Because data based on national population samples are unavailable for most specific musculoskeletal conditions, we derived data from various smaller survey samples from defined populations. Prevalence estimates from these surveys were linked to 1990 US Bureau of the Census population data to calculate national estimates. We also estimated the expected frequency of arthritis in the year 2020. RESULTS: Current national estimates are provided, with important caveats regarding their interpretation, for self-reported arthritis and selected conditions. An estimated 15% (40 million) of Americans had some form of arthritis in 1995. By the year 2020, an estimated 18.2% (59.4 million) will be affected. CONCLUSION: Given the limitations of the data on which they are based, this report provides the best available prevalence estimates for arthritis and other rheumatic conditions overall, and for selected musculoskeletal disorders, in the US population. 相似文献
68.
EH Schreiber 《Canadian Metallurgical Quarterly》1997,80(2):636-638
To examine whether group hypnosis would improve college students' achievement examination grades, including a midterm and final test of 30 educational psychology students who were hypnotized were compared with those of two control groups of 34 and 32 students. Analysis indicated for these intact classes the hypnotized group had a significantly higher mean score on final examination than those of the control groups, although differences in examination scores were nonsignificant at midterm. Suggestions for further research are made. 相似文献
69.
70.
Voice disorders related to occupation and work environment are often observed in ENT consultations. Advising these patients requires not only the investigation of their vocal capacities but also knowledge about their vocal load. The patient will name extreme demands as the reason for vocal problems whereas the employer will want to know if the patient is capable of doing the work required of him. For an objective measurement of vocal load, a voice accumulator has been developed. This portable instrument records total speaking time and sound level over a period of several hours. The data can be transferred to a personal computer which analyses voiced time (s) between 60 and 112 dB(A)s. Thus, more precise and objective documentation of vocal demands in some professions can finally be obtained. With these results, it is possible to monitor vocal ability or disability during vocal rehabilitation. 相似文献