全文获取类型
收费全文 | 38094篇 |
免费 | 3753篇 |
国内免费 | 2406篇 |
专业分类
电工技术 | 2234篇 |
技术理论 | 2篇 |
综合类 | 3810篇 |
化学工业 | 931篇 |
金属工艺 | 904篇 |
机械仪表 | 2174篇 |
建筑科学 | 8718篇 |
矿业工程 | 776篇 |
能源动力 | 407篇 |
轻工业 | 423篇 |
水利工程 | 487篇 |
石油天然气 | 963篇 |
武器工业 | 420篇 |
无线电 | 4902篇 |
一般工业技术 | 1101篇 |
冶金工业 | 584篇 |
原子能技术 | 189篇 |
自动化技术 | 15228篇 |
出版年
2024年 | 102篇 |
2023年 | 523篇 |
2022年 | 843篇 |
2021年 | 1017篇 |
2020年 | 1152篇 |
2019年 | 852篇 |
2018年 | 628篇 |
2017年 | 772篇 |
2016年 | 826篇 |
2015年 | 1194篇 |
2014年 | 2398篇 |
2013年 | 1932篇 |
2012年 | 2671篇 |
2011年 | 3100篇 |
2010年 | 2406篇 |
2009年 | 2518篇 |
2008年 | 2700篇 |
2007年 | 3124篇 |
2006年 | 2651篇 |
2005年 | 2387篇 |
2004年 | 1961篇 |
2003年 | 1824篇 |
2002年 | 1354篇 |
2001年 | 1153篇 |
2000年 | 932篇 |
1999年 | 664篇 |
1998年 | 473篇 |
1997年 | 381篇 |
1996年 | 316篇 |
1995年 | 280篇 |
1994年 | 211篇 |
1993年 | 181篇 |
1992年 | 137篇 |
1991年 | 109篇 |
1990年 | 64篇 |
1989年 | 73篇 |
1988年 | 69篇 |
1987年 | 45篇 |
1986年 | 31篇 |
1985年 | 42篇 |
1984年 | 45篇 |
1983年 | 39篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
2.
资源型产业发展为推进国家经济增长和工业化进程提供了重要保障。为深入了解资源型产业的研究情况,以CNKI数据库为数据源,搜集2000—2020年关于资源型产业的核心及以上期刊论文,利用CiteSpace软件从发文作者与研究机构分布、关键词共现网络和时区图谱等方面,绘制知识图谱,进行可视化分析。研究发现:资源型产业领域的研究成果愈加丰富,但研究群体间联系合作较少,且现有的合作研究主要集中在所处地域资源富集和具有学科优势的研究机构及学者;资源型产业领域的研究热点可概括为产业发展、资源型城市、产业集群、产业结构、产业链和产业集聚等方面;针对资源型产业领域未来可从资源型产业相关理论研究、创新发展模式和可持续发展等方面深入展开。 相似文献
3.
Software is a central component in the modern world and vastly affects the environment’s sustainability. The demand for energy and resource requirements is rising when producing hardware and software units. Literature study reveals that many studies focused on green hardware; however, limited efforts were made in the greenness of software products. Green software products are necessary to solve the issues and problems related to the long-term use of software, especially from a sustainability perspective. Without a proper mechanism for measuring the greenness of a particular software product executed in a specific environment, the mentioned benefits will not be attained. Currently, there are not enough works to address this problem, and the green status of software products is uncertain and unsure. This paper aims to identify the green measurements based on sustainable dimensions in a software product. The second objective is to reveal the relationships between the elements and measurements through empirical study. The study is conducted in two phases. The first phase is the theoretical phase, where the main components, measurements and practices that influence the sustainability of a software product are identified. The second phase is the empirical study that involved 103 respondents in Malaysia investigating current practices of green software in the industrial environment and further identifying the main sustainability dimensions and measurements and their impact on achieving green software products. This study has revealed seven green measurements of software product: Productivity, Usability, Cost Reduction, Employee Support, Energy Efficiency, Resource Efficiency and Tool Support. The relationships are statistically significant, with a significance level of less than 0.01 (p = 0.000). Thus, the hypothesised relationships were all accepted. The contributions of this study revolve around the research perspectives of the measurements to attain a green software product. 相似文献
4.
Yumin An Yi Yang Yongna Jia Wenbo Han Yehong Cheng 《Journal of the American Ceramic Society》2022,105(4):2385-2391
Biomimetic Bouligand architecture is constructed in the ceramic to improve its toughness. Firstly, unidirectional carbon fiber-reinforced ZrB2-SiC ceramic films are achieved through a vacuum-assisted filtration method using graphene oxide. Then, ceramic films are helically assembled at a fixed angle of 30° in the graphite die based on the fiber orientation. Finally, the spark plasma sintering method was utilized to densify helical assembly carbon fiber/ceramic films. By constructing Bouligand structure, high fracture toughness (7.4 MPa·m0.5) and work of fracture (∼1055 J/m2) are achieved in ZrB2-based ceramic. The toughening mechanisms mainly are crack deflection, twisting and branching, carbon fiber pulling out, and bridging. 相似文献
5.
M.S. AlBuriahi H.H. Hegazy Faisal Alresheedi I.O. Olarinoye H. Algarni H.O. Tekin H.A. Saudi 《Ceramics International》2021,47(5):5951-5958
This research article aims to study the effect of CdO addition on the radiation shielding characteristics of boro-tellurite glasses in the composition of 50B2O3 - (50-x) TeO2- xCdO, where x = 0, 10, 20, 30, 40 and 50 mol%. These glasses were exposed to gamma radiation and the transmitted gamma photons were evaluated for energies varying from 15 keV to 15 MeV using Geant4 simulation toolkit. The number of transmitted photons was then used to characterize the gamma shielding for the studied glasses in terms of linear/mass attenuation coefficients, MFP, Zeff, and HVL. The simulation outcomes were theoretically confirmed by using Phy-X software. The beta (electron) shielding characterization of the involved glasses was also investigated by determining the projectile range and stopping power using ESTAR software. Additionally, the fast neutron shielding characterization of the glasses was achieved by evaluating removal cross-section (ΣR). The results reveal that the CdO has a small influence on the shielding performance of the boro-tellurite glasses against gamma, beta, and neutron radiations. The shielding performance of the boro-tellurite glasses was compared with that of common shielding materials in terms of MFP. It can be concluded that the boro-tellurite glasses regardless of the concentration of CdO content have promising shielding performance to be used for radiation applications. 相似文献
6.
7.
Keun-Young Shin Sung Gook Jin Bong June Sung 《Nanoscale and Microscale Thermophysical Engineering》2018,22(1):39-51
Preparation of three-dimensional (3D) networks has received significant attention as an effective approach for applications involving transport phenomena, such as thermal management materials, and several nanomaterials have been examined as potential building blocks of 3D networks for the improvement of heat conduction in polymer nanocomposites. For that purpose, nanocarbons such as graphene and graphite nanoplatelets have been spotlighted as suitable filler materials because of their excellent thermal conductivities (ca. 102–103 W·(m·K)?1 along their lateral axes) and morphological merits. However, the implications of morphological features such as the lateral length and thickness of graphene or graphene-like materials have not yet been identified. In this study, a controlled dissociation of bulk graphite to graphite nanosheets (GNSs) using a low-cost, ecofriendly bead mill process was extensively examined and, when configured in a 3D framework architecture formation, the size-controlled GNSs demonstrated that the thermal conductivities of a 3D interconnected framework of GNSs and the corresponding polymer nanocomposite were intimately correlated with the size of the GNSs, thus demonstrating the successful preparation of an efficient thermal management material without highly sophisticated efforts. The capability of controlling the lateral size and thickness of the GNSs as well as the use of a 3D interconnected framework architecture should greatly assist the commercialization of high-quality graphene-based thermal management materials in a scalable production process. 相似文献
8.
随着高校办学规模的不断扩大,原基于师生服务中心的现场人工报修方式,已无法满足日益增长的后勤报修维修的需求。根据学校的实际情况,对学校后勤管理系统进行分析,得出高职院后勤管理系统应满足在线报修、在线查看、维修反馈、在线评价等功能的需求;同时对高校后勤报修系统进行系统架构设计、网络架构设计、UML类图设计、数据库设计等。通过C#完成系统的编写,最终实现后勤报修系统的开发。 相似文献
9.
In this paper, we describe the design and the management of an agent-based system that supports distributed brainstorming activities. The support system is a highly coordinated IoT application composed of many locally installed interface devices, multimedia communication functions, and cloud functions that process application logic and store meeting data. The system is designed to support a variety of brainstorming sessions, so its functionalities must be modifiable and enable the system to be adapted to different environments and user requirements without any loss of performance. System accessibility should be also ensured from any location for any user. These constraints require a flexible and usable support system.We further discuss the aspects of flexibility and usability that are important in a support system for distributed brainstorming, from which we propose a conceptual schema for flexible and usable support systems. To realize this schema, we present a resource-oriented architecture that can modify the brainstorming support system’s structure and functions. Flexibility is achieved thanks to an agent-based system that manages resources and operates on them according to users’ requests.We also describe the system architecture, which is organized around a set of channels dedicated to different services proposed to the users. We present in detail a video channel that ensures user awareness during synchronized activities. We then conduct several experiments verifying the usability of important channels in the architecture and present the results of these experiments.Finally, we discuss experimental scenarios that show how the system owes its adaptability to management based on an agent organization that supports distributed brainstorming and other activities. 相似文献
10.
Richard Herriott 《CoDesign》2018,14(3):203-217
This paper examines patient-involvement in the process used to design new hospitals. Denmark is in the midst of a phase of hospital building. This recent experience is studied by means of expert interviews with senior practitioners involved in three projects. Examined thematically, the data covers the structure of the design process, identification and ranking of stakeholders, the methods of user-involvement and approaches to accessibility. The paper adds new insight on an under-studied area, design for hospitals and makes recommendations for a change of approach to user-participation in their design. It highlights the difficulties in applying the methods of user-centred design and Design for All in large projects. 相似文献