全文获取类型
收费全文 | 3576篇 |
免费 | 18篇 |
专业分类
教育 | 2511篇 |
科学研究 | 551篇 |
各国文化 | 13篇 |
体育 | 151篇 |
综合类 | 7篇 |
文化理论 | 66篇 |
信息传播 | 295篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 33篇 |
2020年 | 23篇 |
2019年 | 40篇 |
2018年 | 96篇 |
2017年 | 139篇 |
2016年 | 201篇 |
2015年 | 143篇 |
2014年 | 85篇 |
2013年 | 179篇 |
2012年 | 170篇 |
2011年 | 185篇 |
2010年 | 101篇 |
2009年 | 46篇 |
2008年 | 85篇 |
2007年 | 72篇 |
2006年 | 63篇 |
2005年 | 707篇 |
2004年 | 483篇 |
2003年 | 315篇 |
2002年 | 145篇 |
2001年 | 72篇 |
2000年 | 43篇 |
1999年 | 32篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有3594条查询结果,搜索用时 15 毫秒
101.
A seven channel polystyrene (PS) microchip has been constructed using a micromilling machine and a high-temperature assembling. Protein A (PA) has been immobilized by a passive sorption on the microchannel walls. Two bioaffinity assays with human immunoglobulin G (hIgG) as a ligand have been carried out. (i) PA as the receptor and fluorescently labeled hIgG (FITC-hIgG) as the ligand, (ii) PA as the receptor with hIgG as the quantified ligand and fluorescently labeled goat anti-human IgG (FITC-gIgG) as the secondary ligand. One incubation step of the assays took only 5 min instead of hours typical for enzyme-linked immunosorbent assay applications. Calibration curves of the dependence of a fluorescence signal on the hIgG concentration in a sample have been obtained in one step due to a parallel arrangement of microchannels. A mathematical model of the PA-FITC-hIgG complex formation in the chip has been developed. The values of the kinetic constant of the PA-FITC-hIgG binding (kon=5.5 m3 mol−1 s−1) and the equilibrium dissociation constant of the formed complex (Kd≤3×10−6 mol m−3) have been obtained by fitting to experimental data. The proposed microchip enables fast evaluation of kinetic and equilibrium constants of ligand-receptor bioaffinity pairs and the ligand quantification. As the use of microfluidic chips for immunoassays is often limited by price, we used procedures and chemicals that allow for an inexpensive construction and operation of the microdevice, e.g., temperature assembling as a fabrication technique, detection via an ordinary digital camera, nonspecific polystyrene as a substrate, passive sorption of biomolecules as an immobilization technique, etc. 相似文献
102.
Adrijana Doroti? Dragana Anton?i? Vanja Radi?i? Biljak Dara Nedi? Andjelo Beleti? 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(3):393-400
Introduction
Hemolysis can occur during sample collection, handling and transport. It is more frequent when the non-laboratory staff performs sampling. The aim of this study was to assess nurses’ knowledge on the causes of hemolysis and consequential impact on the laboratory tests results. Additionally, the differences in knowledge, related to work experience, professional degree and previous education about hemolysis were explored.Materials and methods
An anonymus survey, containing 11 questions on demographics, causes of hemolysis, its impact on biochemical parameters and nurses’ attitude towards additional education in preanalytics, was conducted in four Croatian hospitals. The answers were compared by Chi-squared and Fischer exact test.Results
In total, 562 survey results were collected. Majority of nurses declared familiarity with the term “hemolysis” (99.6%). There were 77% of correct answers regarding questions about the causes of hemolysis, but only 50% when it comes to questions about interference in biochemical tests. The percentage of correct answers about causes was significantly lower (P = 0.029) among more experienced nurses, and higher (P = 0.027) in those with higher professional degree, while influence of previous education was not significant. Also, higher percentage of correct answers about interferences was encountered in nurses with longer work experience (P = 0.039). More than 70% of nurses declared that additional education about preanalytical factors would be beneficial.Conclusion
Croatian nurses are familiar with the definition of hemolysis, but a lack of knowledge about causes and influence on laboratory test results is evident. Nurses are eager to improve their knowledge in this field of preanalytical phase.Key words: hemolysis, nurses, survey, preanalytical phase 相似文献103.
Intellectual capital (IC), leading to sustainable competitiveness shapes the patterns of business reality nowadays. IC disclosure has become a critical necessity in this new framework. Being a novel interdisciplinary study, the aim of this paper was to examine IC disclosure by Greek publicly traded firms implementing association and decision rules. Firms were divided into three classes (low, medium and high) according to their IC disclosure, measured by the content analysis methodology. The association rules of each class were specified, highlighting IC reporting profile and focus of the firms belonging to each class. Firms in the high class were shown to have strongly realised the crucial need for a reporting change. Teamwork, corporate culture and extra-firm potential appeared to be underlined. Applying the decision tree methodology, the paper succeeded in proving the remuneration–incentive system, R&D and business collaborations items as the IC reporting-related factors differentiating classes. 相似文献
104.
In this paper, social network analysis techniques and regression models are used to explain the impact of the level of knowledge development on ego-network redundancy in a community of hospital physicians. Our findings document that the level of knowledge development and the extent to which knowledge is homogeneously distributed amongst collaborating physicians are related to the redundancy of their advice networks, albeit with opposite effects. Our results highlight also that the impact of these relationships on network redundancy is moderated based on whether partnering individuals belong to different professional groups. Our results provide valuable input for the management of knowledge networks within professional organizations. 相似文献
105.
Despite the large volume of research and managerial literature on knowledge management, many practitioners seem to find it difficult to appreciate its added value for their managerial work. This paper aims to understand and elaborate the added value that knowledge management as a managerial approach can bring to the management of knowledge-intensive organizations. This study explores empirically the actual management practices of a knowledge-intensive organization and examines how knowledge-related phenomena are managed as embedded aspects of management. This paper makes a contribution to prior discussions concerning the relevance of knowledge management and the role of knowledge management as an embedded management practice. The findings of this study should be useful in explaining practitioners the nature, relevance and value of knowledge management. 相似文献
106.
This paper provides an overview of the knowledge management systems (KMSs) adopted by small and medium enterprises (SMEs). KMSs are divided into two categories: knowledge management tools (KM-Tools) and knowledge management practices (KM-Practices). On the basis of the analysis of the literature, two research questions (RQs) were identified and addressed through semi-structured interviews carried out in a sample of 35 SMEs operating in high-tech industries. The first RQ concerns the degree of adoption of KMSs by SMEs. The second RQ regards the relationship between KM-Tools and KM-Practices. As far as the degree of adoption of KMSs, the paper highlights that SMEs are not a homogeneous world but there are a variety of approaches and behaviours. As far as the relationship between the degree of adoption of KM-Tools and KM-Practices, the paper identifies three groups of SMEs that seem to point out the stages of the process of adoption of KMSs: Introduction, SMEs that deal with the process of knowledge management exploiting practices and tools that are already known; Growth, SMEs that adopt specialist practices of knowledge management acquiring new organisational and managerial competence in the field of knowledge management; Maturity, SMEs that invest in new technology and that acquire new technological competence in the field of knowledge management. This categorisation paves the way for further theoretical and practical implications for both managers and policy makers. 相似文献
107.
Bruno Guimarães João Firmino-Machado Stanislav Tsisar Benedita Viana Marco Pinto-Sousa Pedro Vieira-Marques Ricardo Cruz-Correia Maria Amélia Ferreira 《Anatomical sciences education》2019,12(2):138-153
Currently, medical education context poses different challenges to anatomy, contributing to the introduction of new pedagogical approaches, such as computer-assisted learning (CAL). This approach provides insight into students' learning profiles and skills that enhance anatomy knowledge acquisition. To understand the influence of anatomy CAL on spatial abilities, a study was conducted. A total of 671 medical students attending Musculoskeletal (MA) and Cardiovascular Anatomy (CA) courses, were allocated to one of three groups (MA Group, CA Group, MA + CA Group). Students' pre-training and post-training spatial abilities were assessed through Mental Rotations Test (MRT), with scores ranging between 0-24. After CAL training sessions, students' spatial abilities performance improved (9.72 ± 4.79 vs. 17.05 ± 4.57, P < 0.001). Although male students in both MA Group and CA Group show better baseline spatial abilities, no sex differences were found after CAL training. The improvement in spatial abilities score between sessions (Delta MRT) was correlated with Musculoskeletal Anatomy training sessions in MA Group (r = 0.333, P < 0.001) and MA + CA Group (r = 0.342, P < 0.001), and with Cardiovascular Anatomy training sessions in CA Group (r = 0.461, P = 0.001) and MA + CA Group (r = 0.324, P = 0.001). Multiple linear regression models were used, considering the Delta MRT as dependent variable. An association of Delta MRT to the amount of CAL training and the baseline spatial abilities was observed. The results suggest that CAL training in anatomy has positive dose-dependent effect on spatial abilities. 相似文献
108.
Andreas Bauer Jan Romberg Bernhard Sch?tz 《Informatik - Forschung und Entwicklung》2005,49(3):194-205
Zur Beherrschung der komplexen vernetzten und verteilten Funktionen von Automotive-Software ist eine Beschreibung des zu erstellenden
Systems auf verschiedenen Abstraktionsebenen und schrittweise überg?nge zwischen diesen Ebenen notwendig. Neben der Definition
geeigneter Ebenen werden zur Unterstützung echtzeitkritischer Systemanteile ein einheitliches Berechnungsmodell, ebenenspezifische
Beschreibungstechniken, sowie methodische Regeln für diese Abstraktionsebenen eingeführt und in den Werkzeugprototypen AutoFocus integriert. 相似文献
109.
Wolfgang Schr?der-Preikschat Daniel Lohmann Fabian Scheler Olaf Spinczyk 《Informatik - Forschung und Entwicklung》2007,22(1):5-22
Design, implementation, and re-engineering of operating systems are still an ambitious undertaking.
Despite, or even because, of the long history of theory and practice in this field, adapting existing systems
to environments of different conditions and requirements as originally specified or assumed, in terms of
functional and/or non-functional respects, is anything but simple. Especially this is true for the embedded
systems domain which, on the one hand, calls for highly specialized and application-aware system abstractions
and, on the other hand, cares a great deal for easily reusable implementations of these abstractions.
The latter aspect becomes more and more important as embedded systems technology is faced with an innovation
cycle decreasing in length. Software for embedded systems needs to be designed for variability, and this
is in particular true for the operating systems of this domain. The paper discusses dimensions of variability
that need to be considered in the development of embedded operating systems and presents approaches that
aid construction and maintenance of evolutionary operating systems.
CR subject classification C.3; D.2.11; D.2.13; D.4.7 相似文献
110.
Elke Achtert Christian B?hm Peer Kr?ger Peter Kunath Alexey Pryakhin Matthias Renz 《Informatik - Forschung und Entwicklung》2007,15(3):179-195
The reverse k-nearest neighbor (RkNN) problem, i.e. finding all objects in a data set the k-nearest
neighbors of which include a specified query object, has received increasing attention recently. Many
industrial and scientific applications call for solutions of the RkNN problem in arbitrary metric spaces
where the data objects are not Euclidean and only a metric distance function is given for specifying
object similarity. Usually, these applications need a solution for the generalized problem where the
value of k is not known in advance and may change from query to query. In addition, many applications
require a fast approximate answer of RkNN-queries. For these scenarios, it is important to generate
a fast answer with high recall. In this paper, we propose the first approach for efficient approximative
RkNN search in arbitrary metric spaces where the value of k is specified at query time. Our approach
uses the advantages of existing metric index structures but proposes to use an approximation of the
nearest-neighbor-distances in order to prune the search space. We show that our method scales significantly
better than existing non-approximative approaches while producing an approximation of the true query
result with a high recall. 相似文献