全文获取类型
收费全文 | 4110篇 |
免费 | 32篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 13篇 |
综合类 | 16篇 |
化学工业 | 54篇 |
金属工艺 | 13篇 |
机械仪表 | 28篇 |
建筑科学 | 23篇 |
矿业工程 | 13篇 |
能源动力 | 11篇 |
轻工业 | 65篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
武器工业 | 1篇 |
无线电 | 46篇 |
一般工业技术 | 64篇 |
冶金工业 | 3721篇 |
原子能技术 | 10篇 |
自动化技术 | 64篇 |
出版年
2024年 | 10篇 |
2023年 | 9篇 |
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 9篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 15篇 |
2014年 | 19篇 |
2013年 | 35篇 |
2012年 | 27篇 |
2011年 | 24篇 |
2010年 | 21篇 |
2009年 | 25篇 |
2008年 | 17篇 |
2007年 | 14篇 |
2006年 | 15篇 |
2005年 | 26篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 113篇 |
1998年 | 1220篇 |
1997年 | 706篇 |
1996年 | 415篇 |
1995年 | 251篇 |
1994年 | 197篇 |
1993年 | 212篇 |
1992年 | 39篇 |
1991年 | 25篇 |
1990年 | 42篇 |
1989年 | 36篇 |
1988年 | 48篇 |
1987年 | 37篇 |
1986年 | 35篇 |
1985年 | 35篇 |
1983年 | 4篇 |
1982年 | 15篇 |
1981年 | 19篇 |
1980年 | 25篇 |
1979年 | 2篇 |
1978年 | 12篇 |
1977年 | 83篇 |
1976年 | 149篇 |
1975年 | 11篇 |
1955年 | 3篇 |
排序方式: 共有4152条查询结果,搜索用时 0 毫秒
91.
AS Boiadzhian SA Petrosian SA Petrosian KG Karagezian 《Canadian Metallurgical Quarterly》1995,344(6):827-829
92.
PS Gill RT Mitsuyasu T Montgomery J Huang S Cabriales M Testa BM Espina AM Levine SA Miles 《Canadian Metallurgical Quarterly》1997,3(5):278-283
The aim of this study was to evaluate psychosocial quality of life after heart transplantation. We examined 29 patients (25 M and 4 F), average age was 43.5 y (18-62 y). The age at time of heart transplantation was 43 years (17-55 y). The time after heart transplantation was 3.3 year (0.3-9 y). Spielberger's Questionnaire of Anxiety, Knobloch's inventory of neuroticism, Freiburg's Personality Inventory and Quality of Life Inventory were used, 33% of patients demonstrated increasing frequency and 29% of patients increasing intensity of neurotic symptoms. 23% of patients presented increasing levels of anxiety (as a state). The personality dimensions (depression, excitability and low emotional stability) displayed high frequency. The results showed that patients were more satisfied with family support, with sexual activities, and less satisfied with financial situation, social activities, social isolations, sleep, memory, excitability, fatigue. 41.5% of patients returned back to work. The results indicate that these psychosocial factors play an important role in quality of life after heart transplantation. That is why if is necessary to dedicate an increasing attention to them. (Tab. 1, Fig. 6, Ref. 14.) 相似文献
93.
94.
95.
96.
Ratnadwip Singha Shuvam Sarkar Arup Ghosh Shubhankar Roy Sajal Barman Mohammad Balal Sudipta Roy Barman Prabhat Mandal 《Advanced Quantum Technologies》2023,6(3):2200116
In recent years, the pursuit of new topological materials has created a vast and ever growing catalogue of compounds. However, the example of elemental topological metals is still rather limited. So far, the non-trivial topological states have been probed in only a handful of elements and that too rarely in a transition metal. By combining the angle-resolved photoemission spectroscopy (ARPES) and magnetotransport measurements, here, ruthenium (Ru) is experimentally confirmed to be a topological metal, validating a recent theoretical prediction. The ARPES data for Ru(0001) provide evidence of the topological surface state related to the bulk Dirac node. Ru also exhibits a prominent planar Hall effect, thus further indicating its Dirac semimetallic nature. Large electron and hole mobilities are estimated, which are comparable to several topological semimetals. The non-trivial nature of electronic band of Ru is also supported by the large non-saturating transverse magnetoresistance. 相似文献
97.
Nishanta Barman Arpita Shome Saurav Kumar Priyam Mondal Karan Jain Mizuki Tenjimbayashi Uttam Manna 《Advanced functional materials》2023,33(22):2214840
Non-sticking droplets wrapped with fine hydrophobic particles, namely liquid marbles, can be transported both on solid and water pool without an undesired spill of the inner encapsulated liquid. While the stimuli-responsive release of the inner liquid in the target area is proposed, the time-programmed release is not yet achieved. Herein, the hydrophobicity of nanoclay is modulated via a catalyst-free 1,4-conjugate addition reaction to form liquid marbles. This nanoclay liquid marble is robust and stable in air but collapses on the liquid pool with a specific lifetime. The lifetime of the liquid marble can be modulated over seconds to hours scale depending on the selection of chemically modulated wettability of the nanoclay. The critical mechanism of lifetime modulation is responsible for controlling the coalescence kinetics between the water pool and inner liquid by nanoclays’ high diffusion length and chemically varied water spreading potential. The NC liquid marble's programmable lifetime to ‘time-bomb’ type drug release and cascade chemical reaction is applied—without requiring any external intervention. 相似文献
98.
Sreya Pal Pratap Kumar Pal Raisa Fabiha Supriyo Bandyopadhyay Anjan Barman 《Advanced functional materials》2023,33(37):2304127
Coupling between spin waves (SWs) and other waves in nanostructured media has emerged as an important topic of research because of the rich physics and the potential for disruptive technologies. Herein, a new phenomenon is reported in this family involving coupling between SWs and hybridized phonon-plasmon waves in a 2D periodic array of magnetostrictive nanomagnets deposited on a silicon substrate with an intervening thin film of aluminium that acts as a source of surface plasmons. Hybridized phonon-plasmon waves naturally form in this composite material when exposed to ultrashort laser pulses and they non-linearly couple with SWs to produce a new breed of waves – acousto-plasmo-spin waves that can exhibit a “frequency comb” spanning more than one octave. This phenomenon, that we call acousto-plasmo-magnonics resulting from tripartite coupling of magnons, phonons and plasmons, is studied with time-resolved magneto-optical-Kerr-effect microscopy. The findings also reveal the presence of parametric amplification in this system; energy is transferred from the hybridized phonon-plasmon modes to the acousto-plasmo-spin wave modes to amplify the latter. This opens a path to design novel active metamaterials with tailored and enhanced response. It may enable high-efficiency magneto-mechanical-plasmonic frequency mixing in the GHz−THz frequency regime and provide a unique avenue to study non-linear coupling, parametric amplification, and frequency comb physics. 相似文献
99.
针对产品结构设计要素之间存在非功能作用且作用关系形式不统一、不易识别、表达拓展性差等问题,提出了基于结构可拓模型的产品结构方案再设计方法。考虑非功能作用与结构的关联关系,基于可拓理论提出产品结构基元概念,即实体元、交互元、可供性元,并基于此构建产品结构可拓模型,用于表达产品结构设计要素及作用关系。借助需求—可供性—交互关系—结构多个设计域映射机制,通过需求—可供性映射挖掘产品待改进可供性,通过可供性—交互关系—结构映射确定产品待改进结构。对可供性元进行拓展分析得到产品可行结构方案集。采用优度评价法选取最优结构方案。给出结构可拓变换规则,实现产品结构再设计方案。最后以跟腱康复装置再设计为例,验证了所提出方法的可行性和有效性。 相似文献
100.
The convection in a vertical channel filled with a porous medium saturated by a nanofluid is studied numerically. The effects of Brownian motion and thermophoresis are incorporated in the model used for nanofluid. Also, the flow within the porous region is governed by Brinkman's equation. The generalized eigenvalue problem for the perturbed state is obtained from a normal mode analysis and solved using the Chebyshev spectral collocation method. The Rayleigh number is expressed as an implicit function of the wavenumber with other parameters. The critical wavenumber and the critical Rayleigh number are calculated for different parameters. The preferred modes under critical conditions are detected. 相似文献