全文获取类型
收费全文 | 2465篇 |
免费 | 78篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 21篇 |
综合类 | 5篇 |
化学工业 | 948篇 |
金属工艺 | 39篇 |
机械仪表 | 41篇 |
建筑科学 | 318篇 |
矿业工程 | 6篇 |
能源动力 | 65篇 |
轻工业 | 188篇 |
水利工程 | 16篇 |
石油天然气 | 2篇 |
武器工业 | 4篇 |
无线电 | 122篇 |
一般工业技术 | 311篇 |
冶金工业 | 127篇 |
原子能技术 | 32篇 |
自动化技术 | 300篇 |
出版年
2022年 | 16篇 |
2021年 | 52篇 |
2020年 | 29篇 |
2019年 | 28篇 |
2018年 | 34篇 |
2017年 | 25篇 |
2016年 | 77篇 |
2015年 | 59篇 |
2014年 | 62篇 |
2013年 | 112篇 |
2012年 | 93篇 |
2011年 | 131篇 |
2010年 | 103篇 |
2009年 | 104篇 |
2008年 | 100篇 |
2007年 | 91篇 |
2006年 | 96篇 |
2005年 | 87篇 |
2004年 | 73篇 |
2003年 | 50篇 |
2002年 | 62篇 |
2001年 | 49篇 |
2000年 | 53篇 |
1999年 | 67篇 |
1998年 | 55篇 |
1997年 | 56篇 |
1996年 | 53篇 |
1995年 | 54篇 |
1994年 | 43篇 |
1993年 | 29篇 |
1992年 | 41篇 |
1991年 | 40篇 |
1990年 | 31篇 |
1989年 | 40篇 |
1988年 | 26篇 |
1987年 | 33篇 |
1986年 | 30篇 |
1985年 | 23篇 |
1984年 | 30篇 |
1983年 | 27篇 |
1982年 | 17篇 |
1981年 | 29篇 |
1980年 | 23篇 |
1979年 | 19篇 |
1978年 | 19篇 |
1977年 | 22篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 21篇 |
1973年 | 19篇 |
排序方式: 共有2545条查询结果,搜索用时 375 毫秒
41.
42.
High Conductivity in Molecularly p‐Doped Diketopyrrolopyrrole‐Based Polymer: The Impact of a High Dopant Strength and Good Structural Order 下载免费PDF全文
Yevhen Karpov Tim Erdmann Ivan Raguzin Mahmoud Al‐Hussein Marcus Binner Uwe Lappan Manfred Stamm Kirill L. Gerasimov Tetyana Beryozkina Vasiliy Bakulev Denis V. Anokhin Dimitri A. Ivanov Florian Günther Sibylle Gemming Gotthard Seifert Brigitte Voit Riccardo Di Pietro Anton Kiriy 《Advanced materials (Deerfield Beach, Fla.)》2016,28(28):6003-6010
43.
Daniele Colombo Slah Drira Ralf Frotscher Manfred Staat 《International journal for numerical methods in engineering》2023,124(2):402-433
Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element. 相似文献
44.
To understand the handling behaviour of a three-wheeled tilting vehicle, models of the vehicle with different level of detail,
corresponding to specific fields of investigation, have been developed. Then the proposed kinematics of the three-wheeler
are assessed and optimized with respect to desired dynamic properties by applying a detailed multibody system model. The partially
unstable nature of the motion of the vehicle suggests the application of an analytically derived, simplified model, to allow
for focusing on stability aspects and steady-state handling properties. These investigations reveal the necessity of employing
a steer-by-wire control system to support the driver by stabilizing the motion of the vehicle. Thus, an additional basic vehicle
model is derived for control design, and an energy-efficient control strategy is presented. Numerical simulation results demonstrate
the dynamic properties of the optimized kinematics and the control system, approved by successful test runs of a prototype. 相似文献
45.
46.
This paper proves several generic variants of context lemmas and thus contributes to improving the tools for observational semantics of deterministic and non-deterministic higher-order calculi that use a small-step reduction semantics. The generic (sharing) context lemmas are provided for may- as well as two variants of must-convergence, which hold in a broad class of extended process- and extended lambda calculi, if the calculi satisfy certain natural conditions. As a guide-line, the proofs of the context lemmas are valid in call-by-need calculi, in call-by-value calculi if substitution is restricted to variable-by-variable and in process calculi like variants of the -calculus. For calculi employing beta-reduction using a call-by-name or call-by-value strategy or similar reduction rules, some iu-variants of ciu-theorems are obtained from our context lemmas. Our results reestablish several context lemmas already proved in the literature, and also provide some new context lemmas as well as some new variants of the ciu-theorem. To make the results widely applicable, we use a higher-order abstract syntax that allows untyped calculi as well as certain simple typing schemes. The approach may lead to a unifying view of higher-order calculi, reduction, and observational equality. 相似文献
47.
Ahmed Fadl Zongqin Zhang Sebastian Geller Jonas Tölke Manfred Krafczyk Donna Meyer 《Microsystem Technologies》2009,15(9):1379-1387
The efficiency of the valve-less rectification micropump depends primarily on the microfluidic diodicity (the ratio of the
backward pressure drop to the forward pressure drop). In this study, different rectifying structures, including the conventional
structures (nozzle/diffuser and Tesla structures), were investigated at very low Reynolds numbers (between 0.2 and 60). The
rectifying structures were characterized with respect to their design, and a numerical approach was illustrated to calculate
the diodicity for the rectifying structures. In this study, the microfluidic diodicity was evaluated numerically for different
rectifying structures including half circle, semicircle, heart, triangle, bifurcation, nozzle/diffuser, and Tesla structures.
The Lattice Boltzmann Method (LBM) was utilized as a numerical method to simulate the fluid flow in the microscale. The results
suggest that at very low Reynolds number flow, rectification and multifunction micropumping may be achievable by using a number
of the presented structures. The results for the conventional structures agree with the reported results. 相似文献
48.
49.
A fundamental challenge for enterprises is to ensure compliance of their business processes with imposed compliance rules stemming from various sources, e.g., corporate guidelines, best practices, standards, and laws. In general, a compliance rule may refer to multiple process perspectives including control flow, time, data, resources, and interactions with business partners. On one hand, compliance rules should be comprehensible for domain experts who must define, verify, and apply them. On the other, these rules should have a precise semantics to avoid ambiguities and enable their automated processing. Providing a visual language is advantageous in this context as it allows hiding formal details and offering an intuitive way of modeling the compliance rules. However, existing visual languages for compliance rule modeling have focused on the control flow perspective so far, but lack proper support for the other process perspectives. To remedy this drawback, this paper introduces the extended Compliance Rule Graph language, which enables the visual modeling of compliance rules with the support of multiple perspectives. Overall, this language will foster the modeling and verification of compliance rules in practice. 相似文献
50.
During the last years a new generation of process-aware information systems has emerged, which enables process model configurations at buildtime as well as process instance changes during runtime. Respective model adaptations result in a large number of model variants that are derived from the same process model, but slightly differ in structure. Generally, such model variants are expensive to configure and maintain. In this paper we address two scenarios for learning from process model adaptations and for discovering a reference model out of which the variants can be configured with minimum efforts. The first one is characterized by a reference process model and a collection of related process variants. The goal is to improve the original reference process model such that it fits better to the variant models. The second scenario comprises a collection of process variants, while the original reference model is unknown; i.e., the goal is to “merge” these variants into a new reference process model. We suggest two algorithms that are applicable in both scenarios, but have their pros and cons. We provide a systematic comparison of the two algorithms and further contrast them with conventional process mining techniques. Comparison results indicate good performance of our algorithms and also show that specific techniques are needed for learning from process configurations and adaptations. Finally, we provide results from a case study in automotive industry in which we successfully applied our algorithms. 相似文献