全文获取类型
收费全文 | 371篇 |
免费 | 0篇 |
专业分类
化学工业 | 3篇 |
金属工艺 | 4篇 |
机械仪表 | 2篇 |
建筑科学 | 16篇 |
能源动力 | 1篇 |
轻工业 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 5篇 |
冶金工业 | 333篇 |
自动化技术 | 5篇 |
出版年
2020年 | 1篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2005年 | 2篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 9篇 |
1998年 | 91篇 |
1997年 | 55篇 |
1996年 | 37篇 |
1995年 | 27篇 |
1994年 | 17篇 |
1993年 | 22篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1978年 | 2篇 |
1977年 | 9篇 |
1976年 | 30篇 |
1975年 | 2篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
31.
An effective topical and regional anesthetic technique using 25% cocaine paste combined with intravenous midazolam hydrochloride was used in 554 patients undergoing functional endoscopic sinus surgery. The operative fields were excellent and all procedures were completed with little patient disturbance. Patients recovered rapidly from sedation and were usually fit for discharge on the same day. There were no anesthetic complications. The major surgical complication rate was 0.5%. 相似文献
32.
33.
Roberta Capello 《Papers in Regional Science》1994,73(2):189-208
ABSTRACT This paper focuses on the idea that new telecommunication technologies are "enabling technologies" for processes of industrial and spatial restructuring. How-ever, they remain only a necessary and not a sufficient condition to generate processes of decentralization of industrial activities and local development. A vast literature on the effects of now information technologies ou industrial restructuring and regional development has been reviewed, with the aim of focusing on the linkages between new telecommunication technologies and the economic characteristics of new industrial and spatial systems. The paper is divided into two parts. The first part analyzes in depth the nature of the new technologies in order to understand their real capacity and potential to reshape industrial and spatial systems. An interpretation on the technological, organizational and economic features of adoption processes is crucial Id understand the real capabilities of these technologies. The second part is focused on an empirical investigation of the effects of these new technologies on the location of industrial activities, and, conse quently, on local development, for a sample of firms located in Italy. 相似文献
34.
35.
EA Halm MJ Fine TJ Marrie CM Coley WN Kapoor DS Obrosky DE Singer 《Canadian Metallurgical Quarterly》1998,279(18):1452-1457
CONTEXT: Many groups have developed guidelines to shorten hospital length of stay in pneumonia in order to decrease costs, but the length of time until a patient hospitalized with pneumonia becomes clinically stable has not been established. OBJECTIVE: To describe the time to resolution of abnormalities in vital signs, ability to eat, and mental status in patients with community-acquired pneumonia and assess clinical outcomes after achieving stability. DESIGN: Prospective, multicenter, observational cohort study. SETTING: Three university and 1 community teaching hospital in Boston, Mass, Pittsburgh, Pa, and Halifax, Nova Scotia. PATIENTS: Six hundred eighty-six adults hospitalized with community-acquired pneumonia. MAIN OUTCOME MEASURES: Time to resolution of vital signs, ability to eat, mental status, hospital length of stay, and admission to an intensive care, coronary care, or telemetry unit. RESULTS: The median time to stability was 2 days for heart rate (< or =100 beats/min) and systolic blood pressure (> or =90 mm Hg), and 3 days for respiratory rate (< or =24 breaths/min), oxygen saturation (> or =90%), and temperature (< or =37.2 degrees C [99 degrees F]). The median time to overall clinical stability was 3 days for the most lenient definition of stability and 7 days for the most conservative definition. Patients with more severe cases of pneumonia at presentation took longer to reach stability. Once stability was achieved, clinical deterioration requiring intensive care, coronary care, or telemetry monitoring occurred in 1% of cases or fewer. Between 65% to 86% of patients stayed in the hospital more than 1 day after reaching stability, and fewer than 29% to 46% were converted to oral antibiotics within 1 day of stability, depending on the definition of stability. CONCLUSIONS: Our estimates of time to stability in pneumonia and explicit criteria for defining stability can provide an evidence-based estimate of optimal length of stay, and outline a clinically sensible approach to improving the efficiency of inpatient management. 相似文献
36.
37.
38.
WN Roberts JP Brodeur J DeWitt SZ Carr CM Wise ME Carr 《Canadian Metallurgical Quarterly》1996,47(11):1081-1087
Electroimmunodiffusion (Laurell rocket) determinations of factor VIII-related antigen in plasma were ordered to determine the cost/benefit ratio for factor VIII-related antigen as a putative test for endothelial damage in suspected vasculitis. Twenty-seven consecutive patients referred for vasculitis or suspected vasculitis were identified and followed up for an average of 9.1 +/- months (range: one to thirty-three months) in a prospective, unblinded study performed in a clinic, associated with a 1054-bed inner-city university hospital. There was no difference in Westergren erythrocyte sedimentation rate (WESR) in patients with final diagnosis of systemic vasculitis (SV) (38 +/- 12 mm/hour) compared to those without vasculitis (NV) (27 +/- 7) as the final diagnosis. The mean plasma concentration of factor VIII-related antigen was significantly elevated in SV (344 +/- 100%) when compared with NV (147 +/- 39%) (P < 0.016). The factor VIII-related antigen test in this study was 2.56 times more likely (crude odds ratio) than the WESR to contribute to a change in diagnosis or therapy (P = 0.016). Positive and negative predictive values (PPV and NPV) for factor VIII-related antigen (abnormal at greater than 220% of the normal value) were both 70%. PPV and NPV for WESR were 56% and 86%, respectively. The factor VIII-related test was less cost-effective than the WESR in the follow-up period unless it was important to define complete remission or differentiate vasculitis flare from infection. The authors conclude that factor VIII-related antigen is a useful test in the initial diagnosis of vasculitis. 相似文献
39.
40.
WN Rida 《Canadian Metallurgical Quarterly》1996,15(21-22):2393-404; discussion 2405-12
Traditionally, measures of vaccine efficacy have focused on a vaccine's ability to prevent infection or disease. HIV vaccination, however, may have important indirect effects by reducing the level of infectiousness of vaccinees who become infected. This latter effect is not captured by the usual estimators of vaccine efficacy. To obtain an estimate of a vaccine's effect on infectiousness, Koopman and Little have proposed a trial design in which HIV-uninfected couples are randomized to the vaccine or control arm of the study. At least one member is assumed to be at risk of HIV infection from outside the partnership. Using this design, we formulate martingales from counting processes which record the number of infected participants over the course of the trial. An alternative estimator of a vaccine's effect on infectiousness along with an estimate of its variance is derived from these martingales. The precision of the estimate is shown to depend on the secondary attack rate within the couple. High secondary attack rates are required for narrow confidence intervals unless very large studies are contemplated. 相似文献