全文获取类型
收费全文 | 906篇 |
免费 | 5篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 44篇 |
金属工艺 | 18篇 |
机械仪表 | 2篇 |
建筑科学 | 4篇 |
矿业工程 | 1篇 |
能源动力 | 10篇 |
轻工业 | 12篇 |
无线电 | 58篇 |
一般工业技术 | 64篇 |
冶金工业 | 666篇 |
原子能技术 | 3篇 |
自动化技术 | 25篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2015年 | 4篇 |
2014年 | 13篇 |
2013年 | 16篇 |
2012年 | 9篇 |
2011年 | 11篇 |
2010年 | 16篇 |
2009年 | 17篇 |
2008年 | 16篇 |
2007年 | 9篇 |
2006年 | 12篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 20篇 |
1998年 | 181篇 |
1997年 | 114篇 |
1996年 | 74篇 |
1995年 | 67篇 |
1994年 | 35篇 |
1993年 | 41篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1982年 | 6篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 21篇 |
1976年 | 62篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有911条查询结果,搜索用时 62 毫秒
101.
PB Mortier VL Martinot Y Anastassov JF Kulik A Duhamel PN Pellerin 《Canadian Metallurgical Quarterly》1997,34(3):247-255
We have analysed randomized controlled studies which reported the incidence of postoperative nausea and vomiting (PONV) after propofol anaesthesia compared with other anaesthetics (control). Cumulative data of early (0-6 h) and late (0-48 h) PONV were recorded as occurrence or non-occurrence of nausea or vomiting. Combined odds ratio and number-needed-to-treat were calculated for propofol as an induction or maintenance regimen, early or late outcomes, and different emetic events. This was performed for all control event rates and within a range of 20-60% control event rates. We analysed 84 studies involving 6069 patients. The effect of propofol on PONV was dependent mainly on the method of administration, time of measurement and range of control event rates. When all studies were included the number-needed-to-treat to prevent PONV with propofol was more than 9 when used for induction of anaesthesia and at best 6 when used for maintenance. Within the 20-60% control event rate range, best results were achieved with propofol maintenance to prevent early PONV: the number-needed-to-treat to prevent early nausea was 4.7 (95% confidence interval 3.8-6.3), vomiting 4.9 (4-6.1) and any emetic event 4.9 (3.7-7.1). Within the 20-60% control event rate, of five patients treated with propofol for maintenance of anaesthesia, one will not vomit or be nauseated in the immediate postoperative period who would otherwise have vomited or been nauseated. This may be clinically relevant. In all other situations the difference between propofol and control may have reached statistical significance but was of doubtful clinical relevance. Treatment efficacy should be established within a defined range of control event rates for meaningful estimates of efficacy and for comparisons. 相似文献
102.
VL Hendricks-Ferguson 《Canadian Metallurgical Quarterly》1997,14(2):73-80; discussion 81-2
Nursing application of the concept of hope in the pediatric oncology clinical setting is currently in its infancy. This article presents a systematic analysis of the concept of hope for use by the pediatric oncology nurse in the care of the pediatric adolescent oncology patient. The literature review addresses health and illness states as areas significant to the analysis and application of hope. This article defines critical attributes, antecedents, and consequences of hope; constructs case examples (a model, a borderline, and contrary cases); includes an operational definition of adolescent hopefulness; and summarizes empirical referents of hope. Through clinical assessment of hope in the pediatric adolescent oncology patient and ongoing research of hope in this population, evaluation of the potential benefits of hope to this population's adaptation to varying health states will be further demonstrated. 相似文献
103.
IB Shchepotin VL Valetsky VA Chorny M Shabahang RJ Nauta RR Buras SR Evans 《Canadian Metallurgical Quarterly》1997,33(9):1413-1418
Medical consequences of many nuclear accidents on humans are well studied, but the results pertaining to gastric cancer patients who were exposed to radiation as a result of the Chernobyl nuclear accident have not been analysed. In this study, the outcome of the surgical treatment of 68 gastric cancer patients who were exposed to radiation as a result of the Chernobyl nuclear accident was compared with that of 117 consecutive gastric cancer patients from uncontaminated areas of the Ukraine. Patients in the study group was significantly younger than that of the control group. Comparative analysis showed the same frequency of regional metastases (65.7% versus 71.1%, P > 0.05), but a smaller number of distant metastases (23.8% versus 38.1%, P < 0.05) in the study group. 41.2% of patients in the study group underwent total gastrectomy compared to 19.6% of patients in the control group (P = 0.002). Postoperative complications developed in 13.2% of patients in the study group, while postoperative mortality in the study group was 7.3% compared to 1.7% in the control group. A significant decrease in CD16 cells was noted in patients from the study group following the operative procedure. Young age, invasive tumours with smaller number of distant metastases, frequent necessity for total gastrectomy and combined operations with adjacent organs, a higher level of postoperative morbidity and mortality and low levels of natural killer cells (CD16+) with a tendency to decrease after surgery are characteristic of patients with carcinoma of the stomach affected by the Chernobyl accident. 相似文献
104.
LM Vieira da Silva VL Formigli MP Cerqueira L Kruchevsky 《Canadian Metallurgical Quarterly》1997,1(6):444-450
To evaluate vaccination coverage in children 0 to 5 years of age, a cross-sectional study based on a household survey was carried out in 1992 in the Pau de Lima Health District, Salvador, Bahia, Brazil, using a cluster sampling technique. The district was subdivided into 30 small areas that were homogeneous with respect to socioeconomic characteristics. Information on the vaccination status of 385 children was obtained through verification of a vaccination card or campaign voucher, or, in the absence of these items, through verbal confirmation from the mother or other responsible person. Based on all the sources of information, the study found vaccination coverage rates in the entire age range of 69% for polio vaccine; 56% for DTP; 74% for measles vaccine; and 87% for BCG. These results suggest that rates obtained from routine records of the health services and vaccination campaigns may be overestimates. The authors discuss the implications of the low coverage rates found in the entire age group and especially among children under 1 year old. 相似文献
105.
SC Finnemann VL Bonilha AD Marmorstein E Rodriguez-Boulan 《Canadian Metallurgical Quarterly》1997,94(24):12932-12937
Phagocytosis of shed photoreceptor rod outer segments (ROS) by the retinal pigment epithelium (RPE) is essential for retinal function. Here, we demonstrate that this process requires alpha(v)beta5 integrin, rather than alpha(v)beta3 integrin utilized by systemic macrophages. Although adult rat RPE expressed both alpha(v)beta3 and alpha(v)beta5 integrins, only alpha(v)beta3 was expressed at birth, when the retina is immature and phagocytosis is absent. Expression of alpha(v)beta5 was first detected in RPE at PN7 and reached adult levels at PN11, just before onset of phagocytic activity. Interestingly, alpha(v)beta5 localized in vivo to the apical plasma membrane, facing the photoreceptors, and to intracellular vesicles, whereas alpha(v)beta3 was expressed basolaterally. Using quantitative fluorimaging to assess in vitro uptake of fluorescent particles by human (ARPE-19) and rat (RPE-J) cell lines, alpha(v)beta5 function-blocking antibodies were shown to reduce phagocytosis by drastically decreasing (85%) binding of ROS but not of latex beads. In agreement with a role for alpha(v)beta5 in phagocytosis, immunofluorescence experiments demonstrated codistribution of alpha(v)beta5 integrin with internalized ROS. Control experiments showed that blocking alpha(v)beta3 function with antibodies did not inhibit ROS phagocytosis and that alpha(v)beta3 did not colocalize with phagocytosed ROS. Taken together, our results indicate that the RPE requires the integrin receptor alpha(v)beta5 specifically for the binding of ROS and that phagocytosis involves internalization of a ROS-alpha(v)beta5 complex. Alpha(v)beta5 integrin does not participate in phagocytosis by other phagocytic cells and is the first of the RPE receptors involved in ROS phagocytosis that may be specific for this process. 相似文献
106.
This paper develops a copy network architecture that can maintain the cell sequence integrity in multi-channel ATM switching. The architecture is internally nonblocking in the sense that the copying process of cells is constrained only by the availability of output channels. By using a relative ordering among the inputs, shared buffering, and a new switching paradigm called the nonblocking binary group network, we show how the cell sequence integrity can be maintained. Next, assuming the fanout request values of cells are distributed independently from cell to cell, we formulate a method of analyzing the performance of the copy network. This method uses the technique of tagged Markov chains to derive the stationary distributions for the number of cells in the copy network from which, delay, throughput, and cell loss probability can be accurately calculated as critical performance measures. We conduct a numerical study for the proposed architecture using this method wherein the effects of key network and traffic variables such as buffer and network sizes, and the mean and the variance of fanout request values are determined under arbitrary types of fanout distribution. Finally, we quantify the performance improvement due to fanout splitting which allows the fanout request from a single cell to be satisfied over multiple time slots 相似文献
107.
BACKGROUND: The physiological and pharmacological consequences of repeated aero-allergen challenge have not been previously characterized in conscious, sensitized guinea-pigs. OBJECTIVES: This study was undertaken to compare the effects of two anti-inflammatory compounds, dexamethasone and Ro 20- 1724, on an acute and chronic airway inflammation, in terms of airway function, reactivity and leucocyte infiltration. METHODS: Sensitized guinea-pigs received eight saline or ovalbumin (OvA) inhalation exposures over 4 weeks and either vehicle, the type 4 PDE inhibitor, Ro 20-1724 (3 mgkg(-1)), or dexamethasone (1.5 mg/kg(-1)), 30 min before and 6 h after each challenge. Airway function of the conscious animal (sGaw) was monitored over the duration of the first and final OvA challenge. Airway reactivity to the thromboxane mimetic, U46619, was also determined following the final OvA exposure as was the leucocyte infiltration. RESULTS: The first antigen challenge induced a large early (0-3h) and smaller late (17-24h) bronchoconstrictor response. Neither phase was affected by the drug treatments. The final OvA challenge induced early and late phase bronchoconstrictor responses but of similar magnitude. The late phase was also significantly prolonged. Ro 20-1724 and dexamethasone significantly attenuated both phases. Airway reactivity to the inhaled thromboxane mimetic, U46619, was also significantly enhanced at 120h after the final OvA exposure in contrast to the saline challenged group. This hyperreactivity was attenuated by Ro 20-1724 and dexamethasone. Bronchoalveolar lavage after repeated OvA exposures revealed eosinophilia which was attenuated by Ro 20-1724 and dexamethasone. CONCLUSIONS: This model demonstrates differential airway responses to acute and chronic antigen challenge. Repeated administration of dexamethasone and Ro 20-1724 with each OvA exposure attenuated all of the chronic inflammatory responses: early and late phase responses, hyperreactivity and eosinophilia. 相似文献
108.
JR Bockoven G Wernovsky VL Vetter TS Wieand TL Spray LA Rhodes 《Canadian Metallurgical Quarterly》1998,66(4):1383-1388
BACKGROUND: The Ross procedure is performed for a variety of left ventricular outflow tract diseases in children. The preoperative hemodynamic burden of pressure or volume overload and associated ventricular hypertrophy can predispose to ventricular arrhythmias. Additional procedures performed with the Ross procedure (eg, Konno) may damage the conduction system. METHODS: Between January 1995 and February 1997, the Ross procedure was performed in 42 patients, 31 (74%) of whom had 71 prior interventions. Concomitant procedures (n = 42 in 23 patients) included 17 annular-enlarging procedures. Screening was performed for perioperative conduction and rhythm abnormalities. RESULTS: There was one postoperative death. Perioperative ventricular tachycardia occurred in 12 patients (29%), with 2 receiving antiarrhythmic medication for ventricular tachycardia at discharge. Transient complete heart block occurred in 3 patients, all of whom had concomitant procedures performed in the subaortic area; all patients were discharged in sinus rhythm and no patient received a permanent pacemaker. CONCLUSIONS: The Ross procedure can be performed successfully in children with complex cardiac disease with low mortality and perioperative morbidity. The incidence of perioperative ventricular tachycardia is high (29%), suggesting the need for vigilant perioperative monitoring and long-term surveillance. 相似文献
109.
110.
Maiti B. Tobin P.J. Okada Y. Reid K.G. Ajuria S.A. Hegde R.I. Kaushik V. 《Electron Device Letters, IEEE》1996,17(6):279-281
Reoxidation of an oxynitride gate dielectric grown by NO anneal of thermal oxide has been studied. This process has demonstrated ~3-5X improvement of QBD of active edge intensive capacitors in comparison to thermal oxide, N2O and NO oxynitride. This improvement is believed to be due to the reduction of local thinning of the gate dielectric at the field oxide edge which also reduces local build-up of positive charge near the gate electrode at the isolation edges 相似文献