全文获取类型
收费全文 | 48145篇 |
免费 | 15259篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 820篇 |
综合类 | 9篇 |
化学工业 | 19645篇 |
金属工艺 | 568篇 |
机械仪表 | 957篇 |
建筑科学 | 2164篇 |
矿业工程 | 115篇 |
能源动力 | 1193篇 |
轻工业 | 8480篇 |
水利工程 | 354篇 |
石油天然气 | 102篇 |
无线电 | 7644篇 |
一般工业技术 | 13482篇 |
冶金工业 | 1643篇 |
原子能技术 | 112篇 |
自动化技术 | 6132篇 |
出版年
2023年 | 103篇 |
2022年 | 224篇 |
2021年 | 537篇 |
2020年 | 1680篇 |
2019年 | 3383篇 |
2018年 | 3430篇 |
2017年 | 3786篇 |
2016年 | 4332篇 |
2015年 | 4213篇 |
2014年 | 4273篇 |
2013年 | 5878篇 |
2012年 | 3239篇 |
2011年 | 3034篇 |
2010年 | 3164篇 |
2009年 | 3049篇 |
2008年 | 2606篇 |
2007年 | 2396篇 |
2006年 | 2082篇 |
2005年 | 1690篇 |
2004年 | 1650篇 |
2003年 | 1575篇 |
2002年 | 1513篇 |
2001年 | 1252篇 |
2000年 | 1230篇 |
1999年 | 595篇 |
1998年 | 241篇 |
1997年 | 215篇 |
1996年 | 176篇 |
1995年 | 135篇 |
1994年 | 157篇 |
1993年 | 124篇 |
1992年 | 101篇 |
1991年 | 79篇 |
1990年 | 86篇 |
1989年 | 74篇 |
1988年 | 66篇 |
1987年 | 69篇 |
1986年 | 58篇 |
1985年 | 76篇 |
1984年 | 70篇 |
1983年 | 66篇 |
1982年 | 65篇 |
1981年 | 63篇 |
1980年 | 50篇 |
1979年 | 66篇 |
1977年 | 59篇 |
1976年 | 44篇 |
1975年 | 37篇 |
1974年 | 36篇 |
1973年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Bijan Nasri‐Nasrabadi Akif Kaynak Shayan Seyedin Zahra Komeily‐Nia Abbas Z Kouzani 《Polymer International》2019,68(5):922-928
Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry 相似文献
2.
Ida-Marie Andersson Björn Bergenståhl Marcela Alexander Marie Paulsson Maria Glantz 《International Journal of Food Science & Technology》2021,56(1):480-492
During whey powder production, the feed is subjected to several heat treatments which can cause lactosylation of proteins. In this study, lactosylation of whey proteins was evaluated in spray-dried powders before and after storage by varying the native protein fraction as well as the serum protein/lactose ratio in the powders. The lactosylation of native α-lactalbumin and β-lactoglobulin in the powders before storage was not affected to a large extent by the protein denaturation or if the feed had been heat treated in a high or low lactose environment. After storage (relative humidity of 23.5%, 30 °C, 25 days), the kinetic of lactosylation tended to increase with increasing native protein fraction and bulk protein content in the powders. An explanation could be that proteins dissolved in the lactose glassy structure might have a lower reactivity, while proteins present in the protein glassy structure with dissolved lactose may display higher lactosylation reactivity. 相似文献
3.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
4.
Karolina Storesund Francine Amon Anne Steen‐Hansen Shayesteh Haghighatpanah Ida Larsson 《火与材料》2021,45(1):181-190
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production. 相似文献
5.
Franois Ancien Fabrizio Pucci Marianne Rooman 《International journal of molecular sciences》2021,22(9)
Sphingomyelin phosphodiesterase (SMPD1) is a key enzyme in the sphingolipid metabolism. Genetic SMPD1 variants have been related to the Niemann-Pick lysosomal storage disorder, which has different degrees of phenotypic severity ranging from severe symptomatology involving the central nervous system (type A) to milder ones (type B). They have also been linked to neurodegenerative disorders such as Parkinson and Alzheimer. In this paper, we leveraged structural, evolutionary and stability information on SMPD1 to predict and analyze the impact of variants at the molecular level. We developed the SMPD1-ZooM algorithm, which is able to predict with good accuracy whether variants cause Niemann-Pick disease and its phenotypic severity; the predictor is freely available for download. We performed a large-scale analysis of all possible SMPD1 variants, which led us to identify protein regions that are either robust or fragile with respect to amino acid variations, and show the importance of aromatic-involving interactions in SMPD1 function and stability. Our study also revealed a good correlation between SMPD1-ZooM scores and in vitro loss of SMPD1 activity. The understanding of the molecular effects of SMPD1 variants is of crucial importance to improve genetic screening of SMPD1-related disorders and to develop personalized treatments that restore SMPD1 functionality. 相似文献
6.
Juliano Henrique Borges Daniel Minutti de Oliveira Sofia Helena Valente de Lemos-Marini Bruno Geloneze Ezequiel Moreira Gonçalves Gil Guerra-Júnior 《Lipids》2021,56(1):101-110
We aimed to compare detailed fat distribution and lipid profile between young adults with congenital adrenal hyperplasia due to 21-hydroxylase enzyme deficiency and a control group. We also verified independent associations of treatment duration and daily hydrocortisone dose equivalent (HDE) with lipid profile within patients. This case–control study included 23 patients (7 male and 16 female) matched by an age range of young adults (18–31 years) with 20 control subjects (8 male and 12 female). Dual energy X-ray absorptiometry was used to measure the fat distribution. Male patients demonstrated elevated indices of fat mass for total (7.7 ± 2.1 vs. 4.5 ± 1.3 kg/m2, p = 0.003), trunk (4.0 ± 1.2 vs. 2.2 ± 0.8 kg/m2, p = 0.005), android (0.63 ± 0.24 vs. 0.32 ± 0.15 kg/m2, p = 0.008), gynoid (1.34 ± 0.43 vs. 0.74 ± 0.24 kg/m2, p = 0.005), arm (0.65 ± 0.16 vs. 0.39 ± 0.10 kg/m2, p = 0.009), and leg regions (2.7 ± 0.8 vs. 1.6 ± 0.4 kg/m2, p = 0.005) than the control group, but not in females. However, female patients demonstrated elevated ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (1.90 ± 0.46 vs. 1.39 ± 0.47, p = 0.009) than the control group, but not in males. Total fat mass was inversely correlated with total testosterone (r = −0.64, p = 0.014) and positively correlated with leptin in males (r = 0.75, p = 0.002). An elevated daily HDE (β = 0.43, p = 0.038 and β = 0.47, p = 0.033) and trunk to total fat mass ratio (β = 0.46, p = 0.025, and β = 0.45, p = 0.037) were independently correlated with impaired lipid profile markers. Although there is no altered lipid profile, male patients demonstrated an increased fat distribution. However, female patients presented with an impaired lipid profile marker but demonstrated close values of normal fat distribution. Interestingly, the dose of glucocorticoid therapy can have some role in the lipid mechanisms. 相似文献
7.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018) 下载免费PDF全文
8.
9.
SPEEK/cSMM membrane for simultaneous electricity generation and wastewater treatment in microbial fuel cell 下载免费PDF全文
10.
Efficacy of Crude and Purified Chitinases (SsChi50) Extracted from Offal Red Scorpion Fish in Biological Control of Chickpea Weevil (Callosobruchus maculatus L.) 下载免费PDF全文