全文获取类型
收费全文 | 171513篇 |
免费 | 34830篇 |
国内免费 | 5909篇 |
专业分类
电工技术 | 55482篇 |
技术理论 | 4篇 |
综合类 | 9431篇 |
化学工业 | 26519篇 |
金属工艺 | 3377篇 |
机械仪表 | 6982篇 |
建筑科学 | 7036篇 |
矿业工程 | 2489篇 |
能源动力 | 13440篇 |
轻工业 | 9073篇 |
水利工程 | 3505篇 |
石油天然气 | 2138篇 |
武器工业 | 790篇 |
无线电 | 23565篇 |
一般工业技术 | 22472篇 |
冶金工业 | 3202篇 |
原子能技术 | 2646篇 |
自动化技术 | 20101篇 |
出版年
2024年 | 414篇 |
2023年 | 1666篇 |
2022年 | 3160篇 |
2021年 | 4180篇 |
2020年 | 6845篇 |
2019年 | 8750篇 |
2018年 | 7879篇 |
2017年 | 9615篇 |
2016年 | 9777篇 |
2015年 | 10117篇 |
2014年 | 13430篇 |
2013年 | 12473篇 |
2012年 | 13850篇 |
2011年 | 14448篇 |
2010年 | 10850篇 |
2009年 | 10530篇 |
2008年 | 10299篇 |
2007年 | 11203篇 |
2006年 | 10019篇 |
2005年 | 8190篇 |
2004年 | 6878篇 |
2003年 | 5830篇 |
2002年 | 4926篇 |
2001年 | 4227篇 |
2000年 | 3597篇 |
1999年 | 2439篇 |
1998年 | 1188篇 |
1997年 | 987篇 |
1996年 | 935篇 |
1995年 | 728篇 |
1994年 | 633篇 |
1993年 | 409篇 |
1992年 | 370篇 |
1991年 | 254篇 |
1990年 | 205篇 |
1989年 | 164篇 |
1988年 | 114篇 |
1987年 | 96篇 |
1986年 | 70篇 |
1985年 | 76篇 |
1984年 | 98篇 |
1983年 | 67篇 |
1982年 | 75篇 |
1981年 | 36篇 |
1980年 | 30篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1977年 | 17篇 |
1976年 | 7篇 |
1959年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Volumetric mass transfer coefficients, kLa, just as power input are considered as essential parameters for mechanically agitated gas‐liquid contactors in relation to their optimization and design. The knowledge of power input is crucial for the prediction of other mass transfer characteristics. A power input correlation is created for the industrial design of the process with a non‐coalescent batch that would be appropriate for a broad range of operational conditions. The recommended resulting correlation is able to predict the power input for impellers in industrial‐scale design for a significant scope of operational conditions. 相似文献
72.
为将我国最严格水资源管理制度的实践与二元水循环理论相结合,提高“三条红线”控制指标的科学性与合理性,本文以SWAT模型为基础,通过改进子流域划分方法、添加经济社会模块和人工用水模块,对其人工侧支循环模拟进行了系统的完善,开发了基于SWAT的水量-水质-水效联合调控模型SWAT_WAQER。以广西南流江流域为例,从国民经济用水量、河道径流与水质等方面对模型进行校验,并在此基础上划分了2030年“三条红线”控制指标。结果表明:该模型性能良好,能够用于不同节水情景下的国民经济用水量、污染物排放量、水功能区水质达标结果分析,可以作为科学制定“三条红线”控制指标的有力支撑工具。 相似文献
73.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
74.
Computer‐Interpretable Guidelines (CIGs) are the dominant medium for the delivery of clinical decision support, given the evidence‐based nature of their source material. Therefore, these machine‐readable versions have the ability to improve practitioner performance and conformance to standards, with availability at the point and time of care. The formalisation of Clinical Practice Guideline knowledge in a machine‐readable format is a crucial task to make it suitable for the integration in Clinical Decision Support Systems. However, the current tools for this purpose reveal shortcomings with respect to their ease of use and the support offered during CIG acquisition and editing. In this work, we characterise the current landscape of CIG acquisition tools based on the properties of guideline visualisation, organisation, simplicity, automation, manipulation of knowledge elements, and guideline storage and dissemination. Additionally, we describe the CompGuide Editor, a tool for the acquisition of CIGs in the CompGuide model for Clinical Practice Guidelines that also allows the editing of previously encoded guidelines. The Editor guides the users throughout the process of guideline encoding and does not require proficiency in any programming language. The features of the CIG encoding process are revealed through a comparison with already established tools for CIG acquisition. 相似文献
75.
The mechanical property of age‐hardenable Al‐alloys is governed by the state of ageing, which determines the microstructure and consequently, their corrosion behavior which is a vital aspect for a number of applications. This article presents a comparative assessment of corrosion behavior of under‐, peak‐ and over‐aged Al‐Mg‐Si alloy. Corrosion characteristics have been determined via immersion tests in 0.1 M ortho‐phosphoric acid solution and intergranular corrosion (IGC) tests. Corroded surfaces are examined by field emission scanning electron micrographs‐energy dispersive spectroscopy and 3D optical profilometer. The obtained results reveal that the corrosion rate at a specific immersion time as well as the depth of IGC increases in the order for under‐, peak‐, and over‐aged states. Irrespective of the state of ageing, corrosion loss increases linearly but the rate of corrosion decreases rapidly with increasing immersion time. The dominant mode of corrosion in under‐aged alloy is identified as localized pitting, while peak‐aged is highly susceptible to IGC in contrast extensive pitting corrosion is observed for over‐aged alloy. The observed differences in corrosion behavior are explained considering characteristics of precipitates. Formation of β (Mg2Si) in case of over‐aged alloy and presence of inclusions like AlFeMnSi particles are found to accelerate pitting corrosion. 相似文献
76.
For rechargeable wireless sensor networks, limited energy storage capacity, dynamic energy supply, low and dynamic duty cycles cause that it is unpractical to maintain a fixed routing path for packets delivery permanently from a source to destination in a distributed scenario. Therefore, before data delivery, a sensor has to update its waking schedule continuously and share them to its neighbors, which lead to high energy expenditure for reestablishing path links frequently and low efficiency of energy utilization for collecting packets. In this work, we propose the maximum data generation rate routing protocol based on data flow controlling technology. For a sensor, it does not share its waking schedule to its neighbors and cache any waking schedules of other sensors. Hence, the energy consumption for time synchronization, location information and waking schedule shared will be reduced significantly. The saving energy can be used for improving data collection rate. Simulation shows our scheme is efficient to improve packets generation rate in rechargeable wireless sensor networks. 相似文献
77.
An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model. 相似文献
78.
79.
A new strategy for the selective coating of tin sulfide (SnS) on the surface of moth‐eye patterned (MEP) conducting polymer film is studied by considering the optical properties of the antireflective moth‐eye pattern and flexibility of polymer films. The semiconductor SnS is selectively coated on the surface of MEP microdomes of poly(3,4‐ethylenedioxythiophene) poly(styrene‐sulfonate) (PEDOT:PSS) film. The SnS coated MEP film is obtained by using pore selectively SnS thin layer functionalized polystyrene honeycomb‐patterned porous (HCP) film as a template. Aqueous PEDOT:PSS solution is poured on the SnS functionalized HCP films and detached for the fabrication of SnS coated MEP films. The films show a satisfactory photo‐responsive property under solar stimulated light illumination due to the antireflective MEP structure of PEDOT film and homogenous SnS coating on the surface of the conducting polymer. 相似文献
80.
This paper considers the state‐dependent interference relay channel (SIRC) in which one of the two users may operate as a secondary user and the relay has a noncausal access to the signals from both users. For discrete memoryless SIRC, we first establish the achievable rate region by carefully merging Han‐Kobayashi rate splitting encoding technique, superposition encoding, and Gelfand‐Pinsker encoding technique. Then, based on the achievable rate region that we derive, the capacity of the SIRC is established in many different scenarios including (a) the weak interference regime, (b) the strong interference regime, and (c) the very strong interference regime. This means that our capacity results contain all available known results in the literature. Next, the achievable rate region and the associated capacity results are also evaluated in the case of additive Gaussian noise. Additionally, many numerical examples are investigated to show the value of our theoretical derivations. 相似文献