全文获取类型
收费全文 | 5304篇 |
免费 | 338篇 |
国内免费 | 7篇 |
学科分类
工业技术 | 5649篇 |
出版年
2023年 | 67篇 |
2022年 | 45篇 |
2021年 | 168篇 |
2020年 | 135篇 |
2019年 | 145篇 |
2018年 | 149篇 |
2017年 | 163篇 |
2016年 | 187篇 |
2015年 | 148篇 |
2014年 | 205篇 |
2013年 | 360篇 |
2012年 | 340篇 |
2011年 | 432篇 |
2010年 | 330篇 |
2009年 | 310篇 |
2008年 | 332篇 |
2007年 | 270篇 |
2006年 | 234篇 |
2005年 | 204篇 |
2004年 | 163篇 |
2003年 | 150篇 |
2002年 | 138篇 |
2001年 | 76篇 |
2000年 | 69篇 |
1999年 | 67篇 |
1998年 | 83篇 |
1997年 | 63篇 |
1996年 | 52篇 |
1995年 | 59篇 |
1994年 | 55篇 |
1993年 | 38篇 |
1992年 | 43篇 |
1991年 | 24篇 |
1990年 | 32篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1987年 | 30篇 |
1986年 | 18篇 |
1985年 | 37篇 |
1984年 | 20篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 26篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 16篇 |
1976年 | 15篇 |
1975年 | 8篇 |
1973年 | 12篇 |
排序方式: 共有5649条查询结果,搜索用时 312 毫秒
31.
Jonathan J. Cook 《Software》2004,34(9):815-845
We discuss P#, our implementation of a tool that allows interoperation between a concurrent superset of the Prolog programming language and C#. This enables Prolog to be used as a native implementation language for Microsoft's .NET platform. P# compiles a linear logic extension of Prolog to C# source code. We can thus create C# objects from Prolog and use C#'s graphical, networking and other libraries. We add language constructs on the Prolog side that allow concurrent Prolog code to be written. A primitive predicate is provided that evaluates a Prolog structure on a newly forked thread. Communication between threads is based on the unification of variables contained in such a structure. It is also possible for threads to communicate through a globally accessible table. All of the new features are available to the programmer through new built-in Prolog predicates. We discuss two software engineering tools implemented using P#. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
32.
The current era of Information, Communication and Media Technologies (ICMT) has ushered in the era of eBusiness and the Information Society where traditional managerial paradigms are challenged and new business models are sought. One central area of managerial discourse is STRATEGY. Based upon a pilot study with leading European managers, consultants and academics, we offer a structured perspective on what may be the shape of things to come for STRATEGIC PLANNING in the context of eBusiness and the Information Society. Normative implications are explored. 相似文献
33.
We show new upper bounds for problems in the W-hierarchy of fixed-parameter complexity. A crucial ingredient of our proofs
is an extension to the W-RAM model, which permits more-powerful operations but remains equivalent to the original. We use
the extended model to give new upper bounds for Subsetsum, Maximum Irredundant Set, and various problems concerning intersection
of finite-state machines. 相似文献
34.
Here, we describe the development of a reacting flow multi-species/combustion methodology, implemented as an extension to the differential reduced ejector analysis (DREA) computer program [Mathematical and computer modeling, vol. 31, 2000, p. 21; Appl. Math. Model. 25 (2001) 427; Comput. Math. Appl. 43(10–11); NASA Contractor Report, 1998]. Use of the single fluid IVP solver framework that was developed for the original DREA model has been directly coupled into the combustion formulation. With these modifications, the analysis has an elementary single step reaction Fuel+Oxidizer→Product combustion capability. Though approximate in nature, the simplicity and efficiency of the DREA formulation make it suitable for its original niche, namely design and preliminary design environments where more complex and expensive models may be inappropriate. 相似文献
35.
36.
37.
It is common knowledge today that application of sound manufacturing concepts and techniques will only provide cost-effective, long-term return when manufacturing functions are totally integrated with the operators, maintenance engineers and other associated personnel. This paper presents a human-centred methodology and its associated knowledge-based tool, to utilize equipment failure information for the purpose of machine down-time minimization. Based upon a structured and rigorous assessment of each breakdown, and combined with total employee participation, continuous improvement of maintenance function and operational effectiveness of equipment can be made a reality. 相似文献
38.
Xiao-Ying Wang Jonathan M. Garibaldi Benjamin Bird Michael W. George 《Applied Intelligence》2007,27(3):237-248
Recently Fourier Transform Infrared (FTIR) spectroscopic imaging has been used as a tool to detect the changes in cellular
composition that may reflect the onset of a disease. This approach has been investigated as a mean of monitoring the change
of the biochemical composition of cells and providing a diagnostic tool for various human cancers and other diseases. The
discrimination between different types of tissue based upon spectroscopic data is often achieved using various multivariate
clustering techniques. However, the number of clusters is a common unknown feature for the clustering methods, such as hierarchical
cluster analysis, k-means and fuzzy c-means. In this study, we apply a FCM based clustering algorithm to obtain the best number
of clusters as given by the minimum validity index value. This often results in an excessive number of clusters being created
due to the complexity of this biochemical system. A novel method to automatically merge clusters was developed to try to address
this problem. Three lymph node tissue sections were examined to evaluate our new method. These results showed that this approach
can merge the clusters which have similar biochemistry. Consequently, the overall algorithm automatically identifies clusters
that accurately match the main tissue types that are independently determined by the clinician. 相似文献
39.
Four studies involving 573 female and 272 male college students demonstrated that multiple forms and measures of aggression were associated with high levels of sensation seeking, impulsivity, and a focus on the immediate consequences of behavior. Multiple regression analyses and structural equation models supported a theoretical model based on the general aggression model (C. A. Anderson & B. J. Bushman, 2002), positing that hostile cognition and negative affect mediate the relationships between the aforementioned individual differences and aggression. Sensation seeking also predicted a desire to engage in physical and verbal aggression. The final study demonstrated that relative to those scoring low, individuals scoring high on the consideration of future consequences are only less aggressive when aggression is likely to carry future costs. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
40.
Handley Simon J.; Evans Jonathan St. B. T.; Thompson Valerie A. 《Canadian Metallurgical Quarterly》2006,32(3):559
Under the suppositional account of conditionals, when people think about a conditional assertion, "if p then q," they engage in a mental simulation in which they imagine p holds and evaluate the probability that q holds under this supposition. One implication of this account is that belief in a conditional equates to conditional probability [P(q/p)]. In this paper, the authors examine a further implication of this analysis with respect to the wide-scope negation of conditional assertions, "it is not the case that if p then q." Under the suppositional account, nothing categorically follows from the negation of a conditional, other than a second conditional, "if p then not-q." In contrast, according to the mental model theory, a negated conditional is consistent only with the determinate state of affairs, p and not-q. In 4 experiments, the authors compare the contrasting predictions that arise from each of these accounts. The findings are consistent with the suppositional theory but are incongruent with the mental model theory of conditionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献