全文获取类型
收费全文 | 6881篇 |
免费 | 103篇 |
国内免费 | 23篇 |
专业分类
电工技术 | 41篇 |
综合类 | 7篇 |
化学工业 | 895篇 |
金属工艺 | 124篇 |
机械仪表 | 82篇 |
建筑科学 | 51篇 |
矿业工程 | 3篇 |
能源动力 | 299篇 |
轻工业 | 195篇 |
水利工程 | 22篇 |
石油天然气 | 7篇 |
无线电 | 346篇 |
一般工业技术 | 809篇 |
冶金工业 | 3828篇 |
原子能技术 | 25篇 |
自动化技术 | 273篇 |
出版年
2023年 | 38篇 |
2022年 | 81篇 |
2021年 | 109篇 |
2020年 | 87篇 |
2019年 | 86篇 |
2018年 | 142篇 |
2017年 | 78篇 |
2016年 | 84篇 |
2015年 | 77篇 |
2014年 | 114篇 |
2013年 | 217篇 |
2012年 | 163篇 |
2011年 | 196篇 |
2010年 | 157篇 |
2009年 | 144篇 |
2008年 | 123篇 |
2007年 | 122篇 |
2006年 | 95篇 |
2005年 | 81篇 |
2004年 | 68篇 |
2003年 | 89篇 |
2002年 | 53篇 |
2001年 | 49篇 |
2000年 | 39篇 |
1999年 | 194篇 |
1998年 | 1298篇 |
1997年 | 690篇 |
1996年 | 506篇 |
1995年 | 246篇 |
1994年 | 240篇 |
1993年 | 228篇 |
1992年 | 74篇 |
1991年 | 73篇 |
1990年 | 78篇 |
1989年 | 77篇 |
1988年 | 66篇 |
1987年 | 73篇 |
1986年 | 72篇 |
1985年 | 67篇 |
1984年 | 37篇 |
1983年 | 46篇 |
1982年 | 37篇 |
1981年 | 32篇 |
1980年 | 40篇 |
1979年 | 33篇 |
1978年 | 28篇 |
1977年 | 67篇 |
1976年 | 148篇 |
1975年 | 12篇 |
1973年 | 11篇 |
排序方式: 共有7007条查询结果,搜索用时 15 毫秒
1.
Prasad Ravi Kumar Madhu Santanoo Ramotra Prashant Edla Damodar Reddy 《Wireless Networks》2021,27(6):4111-4122
Wireless Networks - In Wireless Sensor Networks (WSNs), where power consumption is a huge concern, the improvement of the network’s lifetime is an area of constant study and innovation. The... 相似文献
2.
Mehmet Dorduncu Junuthula Narasimha Reddy 《Journal of Adhesion Science and Technology》2019,33(2):156-186
This study presents an improved mathematical model to analyse the stress wave propagation in adhesively bonded functionally graded (FG) circular cylinders (butt joint) under an axial impulsive load. The volume fractions of the material constituents in the upper and lower cylinders were functionally tailored through the thickness of each cylinder using a power-law. The effective material properties of both cylinders, which are made of aluminum (Al) and silicon carbide (SiC), at any point were predicted by using the Mori–Tanaka homogenization scheme. In this improved model, the governing equations of the wave propagation include the spatial derivatives of local mechanical properties and were discretized by means of the finite difference method. The influence of these spatial derivatives and the compositional gradient exponent on the displacement and stress distributions of the joint was investigated. The material composition variations of both cylinders affected the displacement and stress fields whereas the compositional gradient exponent had a minor effect. The stress concentrations were alleviated in time, the displacement and stress distributions/variations around/along the upper and lower cylinder-adhesive interfaces were significantly affected by the adhesive layer. The spatial derivatives also affected the temporal histories of the displacement and stress components evaluated at the selected critical points of the upper cylinder, adhesive layer and lower cylinder. The consideration of the spatial local material derivatives provided a more accurate mathematical model of wave propagations through the graded layered structures. 相似文献
3.
4.
5.
Prof. Dr. Britto S. Sandanaraj Pavankumar Janardhan Bhandari Mullapudi Mohan Reddy Akshay Bhagwan Lohote Dr. Bankanidhi Sahoo 《Chembiochem : a European journal of chemical biology》2020,21(3):408-416
The custom design of protein–dendron amphiphilic macromolecules is at the forefront of macromolecular engineering. Macromolecules with this architecture are very interesting because of their ability to self-assemble into various biomimetic nanoscopic structures. However, to date, there are no reports on this concept due to technical challenges associated with the chemical synthesis. Towards that end, herein, a new chemical methodology for the modular synthesis of a suite of monodisperse, facially amphiphilic, protein–dendron bioconjugates is reported. Benzyl ether dendrons of different generations (G1–G4) are coupled to monodisperse cetyl ethylene glycol to form macromolecular amphiphilic activity-based probes (AABPs) with a single protein reactive functionality. Micelle-assisted protein labeling technology is utilized for site-specific conjugation of macromolecular AABPs to globular proteins to make monodisperse, facially amphiphilic, protein–dendron bioconjugates. These biohybrid conjugates have the ability to self-assemble into supramolecular protein nanoassemblies. Self-assembly is primarily mediated by strong hydrophobic interactions of the benzyl ether dendron domain. The size, surface charge, and oligomeric state of protein nanoassemblies could be systematically tuned by choosing an appropriate dendron or protein of interest. This chemical method discloses a new way to custom-make monodisperse, facially amphiphilic, protein–dendron bioconjugates. 相似文献
6.
Adem Sreedhar I. Neelakanta Reddy Qui Thanh Hoai Ta Gitae Namgung Eunbin Cho Jin-Seo Noh 《Ceramics International》2019,45(6):6985-6993
In this paper, novel morphology correlation between silver nanowires (AgNWs) and cobalt (Co)-doped ZnO (Co-ZnO) flake-like thin films (nanowire/flake-like) has been proposed for enhanced photoelectrochemical (PEC) water splitting activity. Here in, high-quality AgNWs/Co-ZnO heterostructures enabled superior visible light water splitting activity compared to the pure ZnO and AgNWs/ZnO. To address the strategic effect of AgNWs coupling and transition metal (Co-2?at%) doping into the ZnO host lattice, we have carried out the X-ray diffraction, field emission scanning microscopy, X-ray photoelectron spectroscopy, UV–Vis transmittance, water contact angle and PEC analyses. In this way, PEC water splitting activity was mainly examined by linear sweep voltammetry (I-V), amperometric I-t and photoconversion efficiency (η) studies. The experimental results provide clear evidence of morphology correlation between AgNWs and Co-ZnO flake-like structures for strong visible light absorption. Specifically, AgNWs/Co-ZnO composites exhibited significant enhancement in the photocurrent density (7.0?×?10?4 A/cm2) than AgNWs/ZnO (3.2?×?10?4 A/cm2) and pure ZnO (1.5?×?10?6 A/cm2). As a result, detailed AgNWs/Co-ZnO geometry has great potential for photoconversion efficiency (0.73%). In a word, the merits of controllable AgNWs/Co-ZnO heterostructure are proposed to improve the visible light harvesting and charge carrier generation for energy conversion devices. 相似文献
7.
Vedantham Ramachandran Reddy Edara Sreenivasa 《Multimedia Tools and Applications》2020,79(29-30):21487-21512
Multimedia Tools and Applications - Facial expression is the most common technique is used to convey the expressions of human beings. Due to different ethnicity and age, faces differ from one... 相似文献
8.
Mohan B. Ponnuchamy G. Mohan Muralikrishna Venkateswara Rao Mannava G. Srinivas Reddy 《Ceramics International》2018,44(13):15019-15023
Nanocrystalline nickel oxide (NiO) was prepared from nickel hydroxide by Spark plasma sintering (SPS) and the mechanisms involved in the densification of NiO were studied. Reverse precipitated nickel hydroxide powders were SPS processed at 400, 600 and 700?°C with 70?MPa pressure. Pure NiO with 12?nm crystallite size formed after 400?°C sintering process. However NiO grains had grown to 18 and 38?nm after 600 and 700?°C sintering respectively. NiO pellets prepared using 600 and 700?°C SPS sintering schedules had relative densities of 83% and 94% respectively. Two displacement rate regimes were observed during densification of NiO in both 600 and 700?°C sintering processes. Decomposition of nickel hydroxide and particle sliding of NiO led to first displacement rate maximum while inverse Hall-Petch based plastic deformation facilitated densification during the constant second displacement rate regime. No densification occurred during sintering holding times indicating the limited role that diffusion played during densification. 相似文献
9.
P. Sampath Brijesh Kakarla Raghava Reddy C. Venkata Reddy Nagaraj P. Shetti Raghavendra V. Kulkarni Anjanapura V. Raghu 《化学工程与技术》2020,43(7):1240-1248
Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency. 相似文献
10.