全文获取类型
收费全文 | 5647篇 |
免费 | 226篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 68篇 |
综合类 | 2篇 |
化学工业 | 847篇 |
金属工艺 | 98篇 |
机械仪表 | 67篇 |
建筑科学 | 311篇 |
矿业工程 | 41篇 |
能源动力 | 147篇 |
轻工业 | 575篇 |
水利工程 | 43篇 |
石油天然气 | 32篇 |
武器工业 | 3篇 |
无线电 | 560篇 |
一般工业技术 | 848篇 |
冶金工业 | 1061篇 |
原子能技术 | 52篇 |
自动化技术 | 1123篇 |
出版年
2023年 | 41篇 |
2022年 | 44篇 |
2021年 | 122篇 |
2020年 | 80篇 |
2019年 | 119篇 |
2018年 | 156篇 |
2017年 | 134篇 |
2016年 | 178篇 |
2015年 | 134篇 |
2014年 | 179篇 |
2013年 | 349篇 |
2012年 | 252篇 |
2011年 | 312篇 |
2010年 | 216篇 |
2009年 | 215篇 |
2008年 | 271篇 |
2007年 | 237篇 |
2006年 | 214篇 |
2005年 | 174篇 |
2004年 | 158篇 |
2003年 | 134篇 |
2002年 | 158篇 |
2001年 | 74篇 |
2000年 | 85篇 |
1999年 | 99篇 |
1998年 | 248篇 |
1997年 | 169篇 |
1996年 | 150篇 |
1995年 | 85篇 |
1994年 | 100篇 |
1993年 | 95篇 |
1992年 | 67篇 |
1991年 | 48篇 |
1990年 | 66篇 |
1989年 | 62篇 |
1988年 | 38篇 |
1987年 | 43篇 |
1986年 | 40篇 |
1985年 | 49篇 |
1984年 | 62篇 |
1983年 | 36篇 |
1982年 | 30篇 |
1981年 | 28篇 |
1980年 | 38篇 |
1979年 | 30篇 |
1978年 | 24篇 |
1977年 | 36篇 |
1976年 | 55篇 |
1975年 | 24篇 |
1973年 | 26篇 |
排序方式: 共有5878条查询结果,搜索用时 15 毫秒
51.
Scherer HU Wang J Toes RE van der Woude D Koeleman CA de Boer AR Huizinga TW Deelder AM Wuhrer M 《Proteomics. Clinical applications》2009,3(1):106-115
In several autoimmune disorders, including rheumatoid arthritis (RA), autoantibodies are thought to be the driving force of pathogenicity. Glycosylation of the Fc-part of human Igs is known to modulate biological activity. Hitherto, glycosylation of human IgG-Fc has been analyzed predominantly at the level of total serum IgG, revealing reduced galactosylation in RA. Given the pathogenic relevance of autoantibodies in RA, we wished, in the present study, to address the question whether distinct Fc-glycosylation features are observable at the level of antigen-specific IgG subpopulations. For this purpose, we have developed a method for the microscale purification and Fc-glycosylation analysis of anti-citrullinated peptide antibodies (ACPA). ACPA represent a group of autoantibodies that occur with unique specificity in RA patients. Their presence is associated with increased inflammatory disease activity and rapid joint destruction. Results indicate that ACPA of the IgG1 subclass vary considerably from total serum IgG1 with respect to Fc-galactosylation, with galactosylation being higher on ACPA than on serum IgG1 for some patients, while other patients show higher galactosylation on serum IgG1 than on ACPA. Using this method, studies can be performed on the biological and clinical relevance of ACPA glycosylation within RA patient cohorts. 相似文献
52.
Tomás Sánchez López Damith Chinthana Ranasinghe Bela Patkai Duncan McFarlane 《Information Systems Frontiers》2011,13(2):281-300
Deployment of embedded technologies is increasingly being examined in industrial supply chains as a means for improving efficiency
through greater control over purchase orders, inventory and product related information. Central to this development has been
the advent of technologies such as bar codes, Radio Frequency Identification (RFID) systems, and wireless sensors which when
attached to a product, form part of the product’s embedded systems infrastructure. The increasing integration of these technologies
dramatically contributes to the evolving notion of a “smart product”, a product which is capable of incorporating itself into
both physical and information environments. The future of this revolution in objects equipped with smart embedded technologies
is one in which objects can not only identify themselves, but can also sense and store their condition, communicate with other
objects and distributed infrastructures, and take decisions related to managing their life cycle. The object can essentially
“plug” itself into a compatible systems infrastructure owned by different partners in a supply chain. However, as in any development
process that will involve more than one end user, the establishment of a common foundation and understanding is essential
for interoperability, efficient communication among involved parties and for developing novel applications. In this paper,
we contribute to creating that common ground by providing a characterization to aid the specification and construction of
“smart objects” and their underlying technologies. Furthermore, our work provides an extensive set of examples and potential
applications of different categories of smart objects. 相似文献
53.
We describe a fast, data-driven bandwidth selection procedure for kernel conditional density estimation (KCDE). Specifically, we give a Monte Carlo dual-tree algorithm for efficient, error-controlled approximation of a cross-validated likelihood objective. While exact evaluation of this objective has an unscalable O(n2) computational cost, our method is practical and shows speedup factors as high as 286,000 when applied to real multivariate datasets containing up to one million points. In absolute terms, computation times are reduced from months to minutes. This enables applications at much greater scale than previously possible. The core idea in our method is to first derive a standard deterministic dual-tree approximation, whose loose deterministic bounds we then replace with tight, probabilistic Monte Carlo bounds. The resulting Monte Carlo dual-tree algorithm exhibits strong error control and high speedup across a broad range of datasets several orders of magnitude greater in size than those reported in previous work. The cost of this high acceleration is the loss of the formal error guarantee of the deterministic dual-tree framework; however, our experiments show that error is still amply controlled by our Monte Carlo algorithm, and the many-order-of-magnitude speedups are worth this sacrifice in the large-data case, where cross-validated bandwidth selection for KCDE would otherwise be impractical. 相似文献
54.
An adaptive, real-time, traffic monitoring system 总被引:1,自引:0,他引:1
In this paper we describe a computer vision-based traffic monitoring system able to detect individual vehicles in real-time.
Our fully integrated system first obtains the main traffic variables: counting, speed and category; and then computes a complete
set of statistical variables. The objective is to investigate some of the difficulties impeding existing traffic systems to
achieve balanced accuracy in every condition; i.e. day and night transitions, shadows, heavy vehicles, occlusions, slow traffic
and congestions. The system we present is autonomous, works for long periods of time without human intervention and adapts
automatically to the changing environmental conditions. Several innovations, designed to deal with the above circumstances,
are proposed in the paper: an integrated calibration and image rectification step, differentiated methods for day and night,
an adaptive segmentation algorithm, a multistage shadow detection method and special considerations for heavy vehicle identification
and treatment of slow traffic. A specific methodology has been developed to benchmark the accuracy of the different methods
proposed. 相似文献
55.
Tom Kontogiannis 《Cognition, Technology & Work》2010,12(2):103-118
Distributed supervisory control systems often rely on complex and centralized plans to cope with a variety of unanticipated
situations. Replanning requires practitioners to forgo standard procedures in favor of making simple plans without simplifying,
managing task coupling, and anticipating team needs to provide decentralized and elaborate plans. This article proposes a
plan classification scheme to study what features of plans facilitate or hinder adaptation and a framework to examine how
features of plans influence the cognitive processes of replanning. The plan features have been assigned to the categories
of plan complexity, coupling, and control. Plans are task networks sharing similar features of complexity and coupling to
technical systems. The proposed framework sets out to explore how plan features influence the processes of recognizing plan
disruptions, reviewing challenges and different team stances, repairing plans to resolve new risks, and reacting by coordinating
team efforts to execute plans. The framework draws on the Extended Control Model (ECOM) to integrate the four processes of
replanning into a set of control loops. The benefits of this framework are illustrated in the context of operator training
and decision support. 相似文献
56.
57.
We give an example of a monoid with finitely many left and right ideals, all of whose Schützenberger groups are presentable by finite complete rewriting systems, and so each have finite derivation type, but such that the monoid itself does not have finite derivation type, and therefore does not admit a presentation by a finite complete rewriting system. The example also serves as a counterexample to several other natural questions regarding complete rewriting systems and finite derivation type. Specifically it allows us to construct two finitely generated monoids M and N with isometric Cayley graphs, where N has finite derivation type (respectively, admits a presentation by a finite complete rewriting system) but M does not. This contrasts with the case of finitely generated groups for which finite derivation type is known to be a quasi-isometry invariant. The same example is also used to show that neither of these two properties is preserved under finite Green index extensions. 相似文献
58.
Yongjun Shen Elke Hermans Da Ruan Geert Wets Tom Brijs Koen Vanhoof 《Expert systems with applications》2011,38(12):15262-15272
Data envelopment analysis (DEA) is a powerful analytical research tool for measuring the relative efficiency of a homogeneous set of decision making units (DMUs) by obtaining empirical estimates of relations between multiple inputs and multiple outputs related to the DMUs. To further embody multilayer hierarchical structures of these inputs and outputs in the DEA framework, which are prevalent in today’s performance evaluation activities, we propose a generalized multiple layer DEA (MLDEA) model. Starting from the input-oriented CCR model, we elaborate the mathematical deduction process of the MLDEA model, formulate the weights in each layer of the hierarchy, and indicate different types of possible weight restrictions. Meanwhile, its linear transformation is realized and further extended to the BCC form. To demonstrate the proposed MLDEA model, a case study in evaluating the road safety performance of a set of 19 European countries is carried out. By using 13 hierarchical safety performance indicators in terms of road user behavior (e.g., inappropriate or excessive speed) as the model’s input and 4 layered road safety final outcomes (e.g., road fatalities) as the output, we compute the most optimal road safety efficiency score for the set of European countries, and further analyze the weights assigned to each layer of the hierarchy. A comparison of the results with the ones from the one layer DEA model clearly indicates the usefulness and effectiveness of this improvement in dealing with a great number of performance evaluation activities with hierarchical structures. 相似文献
59.
Tom Oomen Author Vitae Jeroen van de Wijdeven Author Vitae Author Vitae 《Automatica》2009,45(4):981-1666
Iterative Learning Control (ILC) is a control strategy to improve the performance of digital batch repetitive processes. Due to its digital implementation, discrete time ILC approaches do not guarantee good intersample behavior. In fact, common discrete time ILC approaches may deteriorate the intersample behavior, thereby reducing the performance of the sampled-data system. In this paper, a generally applicable multirate ILC approach is presented that enables to balance the at-sample performance and the intersample behavior. Furthermore, key theoretical issues regarding multirate systems are addressed, including the time-varying nature of the multirate ILC setup. The proposed multirate ILC approach is shown to outperform discrete time ILC in realistic simulation examples. 相似文献
60.
James Gray Yang-Hui He Anton Ilderton André Lukas 《Computer Physics Communications》2009,180(1):107-119
We give a simple tutorial introduction to the Mathematica package STRINGVACUA, which is designed to find vacua of string-derived or inspired four-dimensional N=1 supergravities. The package uses powerful algebro-geometric methods, as implemented in the free computer algebra system Singular, but requires no knowledge of the mathematics upon which it is based. A series of easy-to-use Mathematica modules are provided which can be used both in string theory and in more general applications requiring fast polynomial computations. The use of these modules is illustrated throughout with simple examples.