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   96篇
  免费   0篇
教育   23篇
科学研究   34篇
各国文化   2篇
体育   13篇
文化理论   7篇
信息传播   17篇
  2022年   2篇
  2021年   2篇
  2019年   5篇
  2018年   7篇
  2017年   8篇
  2016年   11篇
  2015年   5篇
  2014年   8篇
  2013年   19篇
  2012年   6篇
  2011年   5篇
  2010年   3篇
  2009年   3篇
  2008年   3篇
  2007年   1篇
  2006年   2篇
  2005年   2篇
  2003年   1篇
  2002年   2篇
  1999年   1篇
排序方式: 共有96条查询结果,搜索用时 15 毫秒
51.
This paper discusses Ernst Mach’s interpretation of the principle of energy conservation (EC) in the context of the development of energy concepts and ideas about causality in nineteenth-century physics and theory of science. In doing this, it focuses on the close relationship between causality, energy conservation and space in Mach’s antireductionist view of science. Mach expounds his thesis about EC in his first historical-epistemological essay, Die Geschichte und die Wurzel des Satzes von der Erhaltung der Arbeit (1872): far from being a new principle, it is used from the early beginnings of mechanics independently from other principles; in fact, EC is a pre-mechanical principle which is generally applied in investigating nature: it is, indeed, nothing but a form of the principle of causality. The paper focuses on the scientific-historical premises and philosophical underpinnings of Mach’s thesis, beginning with the classic debate on the validity and limits of the notion of cause by Hume, Kant, and Helmholtz. Such reference also implies a discussion of the relationship between causality on the one hand and space and time on the other. This connection plays a major role for Mach, and in the final paragraphs its importance is argued in order to understand his antireductionist perspective, i.e. the rejection of any attempt to give an ultimate explanation of the world via reduction of nature to one fundamental set of phenomena.  相似文献   
52.

Background:

Presently the necessity of fasting time for coagulation tests is not standardized. Our hypothesis is that this can harm patient safety. This study is aimed at evaluating whether a light meal (i.e. breakfast) can jeopardize laboratory coagulation tests.

Materials and methods:

A blood sample was firstly collected from 17 fasting volunteers (12 h). Immediately after blood collection, the volunteers consumed a light meal. Then samples were collected at 1, 2 and 4 h after the meal. Coagulation tests included: activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen (Fbg), antithrombin III (AT), protein C (PC) and protein S (PS). Differences between samples were assessed by Wilcoxon ranked-pairs test. The level of statistical significance was set at P < 0.05. Mean % differences were determined and differences between and baseline and 1, 2 and 4h samples were compared with reference change value (RCV).

Results:

A significantly higher % activity of AT was observed at 1 h and 4 h after meal vs. baseline specimen [113 (104–117) and 111 (107–120) vs. 109 (102–118), respectively; P = 0.029 and P = 0.016]. APTT at 2 h was found significantly lower than baseline samples [32.0 (29.9–34.8) vs. 34.1 (32.2–35.2), respectively; P = 0.041]. The results of both Fbg and PS tests were not influenced by a light meal. Furthermore, no coagulation tests had significant variation after comparison with RCV.

Conclusion:

A light meal does not influence the laboratory coagulation tests we assessed, but we suggest that the laboratory quality managers standardize the fasting time for all blood tests at 12 hours, to completely metabolize the lipids intake.  相似文献   
53.
54.

Introduction:

The measurement of cardiospecific troponins is pivotal in the diagnostic and prognostic approach of patients with suspected acute myocardial infarction (AMI). However, no information is available on the commutability of results between the novel highly-sensitive (HS) troponin T (TnT) and I (TnI) immunoassays.

Materials and methods:

The study population consisted in 47 consecutive patients presenting at the emergency department (ED) of the Academic Hospital of Parma with suspected AMI. TnI was measured with the novel prototype Beckman Coulter HS-AccuTnI immunoassay on Access 2, whereas TnT was measured with the Roche HS-TnT immunoassay on Cobas.

Results:

Eight out of the 47 patients (17%) were finally diagnosed as having an AMI. The overall correlation between TnT and TnI for total patient group was acceptable (r = 0.944; P < 0.01). Nevertheless, when the analysis of data was carried out in separate groups according to the final diagnosis of AMI, two different equation results were obtained, i.e., HS-TnT = HS-AccuTnI × 0.349 + 20 (r = 0.823; P < 0.01) in non-AMI patients, and HS-TnT = HS-AccuTnI × 0.134 + 67 (r = 0.972; P < 0.01) in those with AMI.

Conclusions:

This study suggests the existence of two biological relationships between TnI and TnT in plasma, depending on the source of release from the myocardium. Moreover, the non-commutability of data between HS-TnT and HS-AccuTnI jeopardizes the clinical decision making, makes it impossible to calculate the delta or reference change value using the two biomarkers and to finally establish a reliable kinetics of troponin release from the injured myocardium.  相似文献   
55.
We investigate if and to what extent the receipt of a “selective” subsidy – a public subsidy awarded through a competitive procedure – helps new technology-based firms (NTBFs) to access R&D alliances. In particular, we theoretically enquire and empirically analyze which founding team-level characteristics allow NTBFs to: i) get a selective subsidy; and ii) access an R&D alliance with another firm or a public research organization/university, once the subsidy is awarded. We use a sample of 902 NTBFs that operate in Italy, where industrial policy has never had an explicit and exclusive mandate neither for targeting NTBFs nor for easing their access to R&D networks. By means of several identification strategies and estimation methods, our results point to the relevance of selective subsidies in facilitating NTBFs to enter R&D alliances, independently from the objective of the policy measure. Second, founders’ technical education figures as a key determinant to get the first selective subsidy. Finally, founders’ previous industry-specific work experience allows NTBFs to better exploit the selective subsidy, by positively moderating the impact of the subsidy on the likelihood to establish a corporate R&D alliance.  相似文献   
56.
It is often argued that small–medium enterprises (SMEs) do not manage knowledge the same way as large firms, but may need appropriate approaches to capture and exploit external knowledge effectively. This paper compares two opposite approaches to knowledge management (KM): one is called ‘deliberate’ or ‘planned’, and the other ‘emergent’. These approaches are analysed with reference to the management of knowledge pertaining to client–supplier relationships, which are particularly important in the case of small companies providing knowledge-intensive business services (KIBS). A case study of a small KIBS company is illustrated, which has developed two different projects, based on different approaches to KM, for managing knowledge referring to clients. The case shows that, for a small company, an emergent approach to KM can be more suitable than a deliberate one for managing such knowledge. The implications of this result for KM research and practice are then examined.  相似文献   
57.
By using a panel design in a sample of 298 undergraduate/master students at an Italian public university, the present study aimed to test longitudinally the interplay among environmental attitudes, pro-environmental behavior, social identity, and pro-environmental institutional climate. The relationships were tested with cross-lagged analysis based on two waves over a 2-month period. The cross-lagged panel analysis revealed positive cross-lagged effects of social identity on environmental attitudes and pro-environmental institutional climate perceptions on social identity. Environmental attitudes and social identity at Time 1 did not predict Time 2 pro-environmental behavior. Pro-environmental behavior at Time 1 did not predict Time 2 environmental attitudes. Pro-environmental institutional climate perceptions at Time 1 did not predict Time 2 pro-environmental behavior. Finally, social identity at Time 1 did not predict Time 2 pro-environmental institutional climate perceptions.  相似文献   
58.

Introduction

In vitro human diagnostic (IVD) company recalls are a common practice aimed to either minimize a potential error or eliminate an existing failure. In this case report, we aim to provide a critical analysis of a recent IVD recall and to provide a practical framework about what to do when an IVD company recalls product(s) based on the International Organization for Standardization - ISO 15189:2012 standard.

Case report

In 2014, Abbott Laboratories® (Green Oaks, IL) published an urgent field safety notice regarding a product recall (Architect Intact parathyroid hormone (PTH) Assay List Number 8K25) with immediate action required. The IVD company explained the reasons for the recall as follows: i) Abbott has confirmed that a performance shift in the Architect Intact PTH assay has the potential to generate falsely elevated results on patient samples; ii) results generated with impacted lots may demonstrate a positive shift relative to those generated with previous reagent and/or calibrator lots. This issue may also impact established Architect Intact PTH reference ranges; iii) the magnitude of shift averages approximately 13% to 45%; iv) Abbott Architect Intact PTH controls do not detect the shift; and v) all current reagent, calibrator, and control inventory are impacted. The recall could have resulted in ~40,000 inaccurate laboratory tests reported by 18 laboratories from Italy (Lombardy region).

Conclusion

IVD company recalls have a serious impact on the patient safety and require a thorough investigation and responsible approach to minimize the possible damage. Medical laboratories accredited according to the ISO 15189 standard have procedures in place to manage such situations and ensure that patient safety is maintained when such recalls are issued.Key words: clinical laboratory techniques, patient safety, laboratory variability, reference standards, quality control, parathyroid hormone  相似文献   
59.
This paper proposes a novel query expansion method to improve accuracy of text retrieval systems. Our method makes use of a minimal relevance feedback to expand the initial query with a structured representation composed of weighted pairs of words. Such a structure is obtained from the relevance feedback through a method for pairs of words selection based on the Probabilistic Topic Model. We compared our method with other baseline query expansion schemes and methods. Evaluations performed on TREC-8 demonstrated the effectiveness of the proposed method with respect to the baseline.  相似文献   
60.
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