全文获取类型
收费全文 | 4794篇 |
免费 | 181篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 84篇 |
综合类 | 4篇 |
化学工业 | 1044篇 |
金属工艺 | 135篇 |
机械仪表 | 100篇 |
建筑科学 | 118篇 |
矿业工程 | 12篇 |
能源动力 | 137篇 |
轻工业 | 232篇 |
水利工程 | 41篇 |
石油天然气 | 18篇 |
无线电 | 555篇 |
一般工业技术 | 899篇 |
冶金工业 | 921篇 |
原子能技术 | 38篇 |
自动化技术 | 655篇 |
出版年
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 71篇 |
2020年 | 66篇 |
2019年 | 58篇 |
2018年 | 84篇 |
2017年 | 75篇 |
2016年 | 94篇 |
2015年 | 79篇 |
2014年 | 105篇 |
2013年 | 302篇 |
2012年 | 137篇 |
2011年 | 191篇 |
2010年 | 189篇 |
2009年 | 216篇 |
2008年 | 167篇 |
2007年 | 158篇 |
2006年 | 166篇 |
2005年 | 131篇 |
2004年 | 146篇 |
2003年 | 126篇 |
2002年 | 128篇 |
2001年 | 135篇 |
2000年 | 111篇 |
1999年 | 122篇 |
1998年 | 157篇 |
1997年 | 117篇 |
1996年 | 122篇 |
1995年 | 98篇 |
1994年 | 101篇 |
1993年 | 103篇 |
1992年 | 79篇 |
1991年 | 79篇 |
1990年 | 86篇 |
1989年 | 89篇 |
1988年 | 88篇 |
1987年 | 62篇 |
1986年 | 54篇 |
1985年 | 57篇 |
1984年 | 56篇 |
1983年 | 56篇 |
1982年 | 37篇 |
1981年 | 37篇 |
1980年 | 42篇 |
1979年 | 29篇 |
1978年 | 34篇 |
1977年 | 36篇 |
1976年 | 49篇 |
1975年 | 32篇 |
1973年 | 30篇 |
排序方式: 共有4993条查询结果,搜索用时 15 毫秒
1.
Jincy Joy Jessica Pereira Rachida Aid‐Launais Graciela Pavon‐Djavid Alok R Ray Didier Letourneur Anne Meddahi‐Pell Bhuvanesh Gupta 《Polymer International》2019,68(7):1367-1377
The work reported involved the fabrication of an electrospun tubular conduit of a gelatin and polycaprolactone (PCL) blend as an adventitia‐equivalent construct. Gelatin was included as the matrix for increased biocompatibility with the addition of PCL for durability. This is contrary to most of the literature available for biomaterials based on blends of gelatin and PCL where PCL is the major matrix. The work includes the assiduous selection of key electrospinning parameters to obtain smooth bead‐free fibres with a narrow distribution of pore size and fibre diameter. Few reports elucidate the optimization of all electrospinning parameters to fabricate tubular conduits with a focus on obtaining homogeneous pores and fibres. This stepwise investigation would be unique for the fabrication of gelatin–PCL electrospun tubular constructs. The fabricated microfibrous gelatin–PCL constructs had pores of size ca 50–100 μm reportedly conducive for cell infiltration. The measured value of surface roughness of 57.99 ± 17.4 nm is reported to be favourable for protein adhesion and cell adhesion. The elastic modulus was observed to be similar to that of the tunica adventitia of the native artery. Preliminary in vitro and in vivo biocompatibility tests suggest safe applicability as a biomaterial. Minimal cytotoxicity was observed using MTT assay. Subcutaneous implantation of the scaffold demonstrated acute inflammation which decreased by day 15. The findings of this study could enable the fabrication of smooth bead‐free microfibrous gelatin–PCL tubular construct as viable biomaterial which can be included in a bilayer or a trilayer scaffold for vascular tissue engineering. © 2019 Society of Chemical Industry 相似文献
2.
Lokesh Kulhari Kanad Ray Ankit Paptan Nikhil Suri Pramod K Khanna 《International Journal of Applied Ceramic Technology》2020,17(3):1430-1439
Low temperature co-fired ceramic (LTCC) micro-hotplates show wide applications in gas sensors and micro-fluidic devices. It is easily structured in three-dimensional structures. This paper presents the low power consumption micro-hotplates which were developed with PTC (positive temperature coefficient) temperature sensor and inter-digitated electrodes. The paper presents two different structures for micro-hotplate with platinum as a heating element. The PTC temperature sensor using two different materials viz. PdAg and platinum paste are developed with micro-hotplates. The simulation has been achieved through COMSOL for LTCC and alumina micro-hotplates. The temperature variation with power consumption has been measured for the developed LTCC micro-hotplates. The change in resistance of PTC temperature sensors was measured with micro-hotplate temperature. The aim of this study was to place a temperature sensor with the gas sensor module to measure and control the temperature of micro-hotplate. A SnO2 sensing layer is coated on LTCC micro-hotplate using screen printing and characterized for the sensing of carbon monoxide gas (CO). This study will be beneficial for designing hotplates based on LTCC technology with low power consumption and better stability of temperature for gas-sensing applications. 相似文献
3.
Juana Maria de Lourdes Medina-Contreras Patrick Mailloux-Salinas Juventino III Colado-Velazquez Norma Leticia Gomez Viquez Gómez-Viquez Rodrigo Velázquez-Espejel Ana del Carmen Susunaga-Notario David Julian Arias-Chávez Guadalupe Bravo 《Journal of the science of food and agriculture》2020,100(7):3212-3219
4.
P. L. Sun E. K. Cerreta G. T. Gray III J. F. Bingert 《Metallurgical and Materials Transactions A》2006,37(10):2983-2994
Commercial purity aluminum AA1050 was subjected to equal channel angular extrusion (ECAE) that resulted in an ultrafine-grained
(UFG) microstructure with an as-received grain size of 0.35 μm. This UFG material was then annealed to obtain microstructures
with grain sizes ranging from 0.47 to 20 μm. Specimens were compressed at quasi-static, intermediate, and dynamic strain rates
at temperatures of 77 and 298 K. The mechanical properties were found to vary significantly with grain size, strain rate,
and temperature. Yield stress was found to increase with decreasing grain size, decreasing temperature, and increasing strain
rate. The work hardening rate was seen to increase with increasing grain size, decreasing temperature, and increasing strain
rate. The influence of strain rate and temperature is most significant in the smallest grain size specimens. The rate of work
hardening is also influenced by strain rate, temperature, and grain size with negative rates of work hardening observed at
298 K and quasi-static strain rates in the smallest grain sizes and increasing rates of work hardening with increasing loading
rate and grain size. Work hardening behavior is correlated with the substructural evolution of these specimens. 相似文献
5.
Jack J. Domet III T.M. Rajkumar Domet III David Yen 《Information Systems Management》1994,11(4):39-45
The realization of digital multimedia's full business potential requires networking. This article discusses the value-added benefits to the corporation of networked multimedia as well as the choice of architectures and technologies needed to deliver multimedia networking solutions. 相似文献
6.
7.
Using Web resources to construct multilingual medical thesaurus for cross-language medical information retrieval 总被引:1,自引:0,他引:1
Due to the language barrier, non-English users are unable to retrieve the most updated medical information from the U.S. authoritative medical websites, such as PubMed and MedlinePlus. However, currently, there is no any cross-language medical information retrieval (CLMIR) system that can help Chinese-speaking consumers cross the language barrier in finding useful English medical information. A few CLMIR systems utilize MeSH (Medical Subject Headings) to help overcome the language barrier. Unfortunately, the traditional Chinese version of MeSH is currently unavailable.In this paper, we employ a semi-automatic term translation method to construct a Chinese–English MeSH by exploiting abundant multilingual Web resources, including Web anchor texts and search–result pages. Through this method, we have developed a Chinese–English Mesh Compilation System to assist knowledge engineers in compiling a Chinese–English medical thesaurus with more than 19,000 entries. Furthermore, this thesaurus has been used to develop a prototypical system for cross-language medical information retrieval, MMODE, which can help consumers retrieve top-quality English medical information using Chinese terms. 相似文献
8.
This paper examines the long-term impact of structural features and physical amenities on the residential satisfaction of renters in multifamily housing. A cumulative logit analysis of 7,206 rented multifamily units in the 2005 American Housing Survey indicates that features creating separated space (additional room, bathroom, garage/carport, or balcony/patio) were associated with significantly higher satisfaction, even when holding total unit area constant. Conversely, violation of space separation by noise intrusion through walls, floors, or ceilings created dramatically negative effects. Other amenities such as a fireplace, disposal, or dishwasher had no statistically significant impact. Tracking a cohort of 5,170 rented multifamily units from 1997 to 2005 revealed somewhat similar effects on the satisfaction trajectory of residents during this period. More bathrooms, bedrooms, and other rooms, as well as the presence of a balcony/patio were associated with satisfaction improvements. Analyzing cohort units undergoing modifications during the tracking period revealed that the addition of a bathroom or central air conditioning had the clearest impact on satisfaction, followed by the addition of a balcony/patio, other room, dishwasher, or garage/carport. 相似文献
9.
10.