全文获取类型
收费全文 | 1274篇 |
免费 | 86篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 588篇 |
金属工艺 | 31篇 |
机械仪表 | 21篇 |
建筑科学 | 39篇 |
矿业工程 | 11篇 |
能源动力 | 58篇 |
轻工业 | 214篇 |
水利工程 | 10篇 |
石油天然气 | 1篇 |
无线电 | 32篇 |
一般工业技术 | 164篇 |
冶金工业 | 23篇 |
原子能技术 | 2篇 |
自动化技术 | 151篇 |
出版年
2024年 | 4篇 |
2023年 | 10篇 |
2022年 | 112篇 |
2021年 | 157篇 |
2020年 | 43篇 |
2019年 | 64篇 |
2018年 | 44篇 |
2017年 | 53篇 |
2016年 | 61篇 |
2015年 | 57篇 |
2014年 | 74篇 |
2013年 | 119篇 |
2012年 | 69篇 |
2011年 | 78篇 |
2010年 | 56篇 |
2009年 | 45篇 |
2008年 | 34篇 |
2007年 | 28篇 |
2006年 | 43篇 |
2005年 | 26篇 |
2004年 | 21篇 |
2003年 | 23篇 |
2002年 | 10篇 |
2001年 | 4篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 5篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1967年 | 1篇 |
排序方式: 共有1362条查询结果,搜索用时 15 毫秒
31.
32.
Ewa Watorek Tomasz Golebiowski Mariusz Kusztal Krzysztof Letachowicz Waldemar Letachowicz Hanna Augustyniak Bartosik Jerzy Garcarek Katarzyna Madziarska Wacław Weyde Marian Klinger 《Hemodialysis international. International Symposium on Home Hemodialysis》2014,18(1):113-117
Elderly patients, defined as octogenarians and nonagenarians, are an increasing population entering renal replacement therapy. Advanced age appears as an exclusive factor negatively influencing dialysis practice. Elderly patients are referred late for the initiation of hemodialysis and more likely are offered catheters rather than arteriovenous fistulae (AVF), which increase mortality and negatively affect quality of life. We present our approach to the creation of vascular access for hemodialysis in this demanding population. In 2006–2012, 39 patients aged 85.9 ± 2.05 with end‐stage renal disease, mainly resulting from ischemic nephropathy, were admitted to the Department of Nephrology to establish permanent vascular access for hemodialysis: preferably AVF. Temporary dialysis catheters were implanted in uremic emergency to bridge the time to fistula creation/maturation. AVF was attempted in 87.2% of the patients. Primary AVF function was achieved in 54% of the patients. Cumulative proportional survival of AVF at months 12 and 24 was 81.5%. Ninety‐four percent of AVF were localized on the forearm: 74% in the distal and 20% in the proximal part. Mean duration of hemodialysis therapy was 20.80 ± 19.45 months. The mean time of AVF use was 15.9 ± 20.2 months. Until present, 38% have been dialyzed using AVF for 31.0 ± 18.8 months. Five patients died with functioning fistula. Eight patients initiated hemodialysis therapy with fistula. During further observation, the use of AVF increased to 62%. Elderly patients should not be denied creation of AVF as a rule. The outcome of AVF benefits more from acknowledging individual vascular conditions rather than age of the patient. 相似文献
33.
Conventional fuels used for supplying internal combustion piston engines include petrols and diesel oils produced from petroleum. These are a non-renewable energy source. The environmental policy of the European Union is geared towards increasing the share of renewable fuels in the overall energy consumption. An alternative fuel originating from a renewable source, which could be used for feeding self-ignition internal combustion engines are the fatty acid methyl esters (FAME) of plant oils. The paper reports selected results of testing a 1.3 MULTIJET SDE 90 PS self-ignition engine with the Common Rail reservoir feed system supplied with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME). Tests were carried out on an engine test bed equipped with an eddy-current brake. The purpose of the tests was to determine the economic–energy and ecological indices of engine operation. The concentrations of exhaust gas gaseous components were measured using a MEXA-1600DEGR analyzer, while the particulate concentrations, with a MEXA-1230PM analyzer. In addition, the variations of working medium pressures in the engine chamber and of fuel pressure upstream the injector were recorded as a function of crankshaft rotation angle using the AVL IndiSmart 612 indication system for this purpose. The physicochemical properties of fuels used in the tests were determined using a fuel analyzer. The obtained testing results made it possible to determine and assess the operation indices of the engine fed with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME) with slightly higher ester contents than the requirements of the currently applicable diesel oil standard. 相似文献
34.
35.
In this work, we aim at quantifying quantum channel output similarity. In order to achieve this, we introduce the notion of quantum channel superfidelity, which gives us an upper bound on the quantum channel fidelity. This quantity is expressed in a clear form using the Kraus representation of a quantum channel. As examples, we show potential applications of this quantity in the quantum control field. 相似文献
36.
37.
Effects of the spray drying conditions of chokeberry (Aronia melanocarpa L.) juice concentrate on the physicochemical properties of powders 下载免费PDF全文
Jolanta Gawałek Ewa Domian Antoni Ryniecki Sławomir Bakier 《International Journal of Food Science & Technology》2017,52(9):1933-1941
A semi‐industrial spray drying process of chokeberry juice concentrate using maltodextrin was analysed. The influence of the content and dextrose equivalent (DE) of maltodextrin, inlet air temperature and rotary disc atomiser speed was studied on the physicochemical properties of the obtained powders. The size and structure of the powder particles, bulk density, moisture content, flowability, yield and total polyphenol content were analysed. An increase in carrier content from 50% to 70% caused a 4.9% increase in total polyphenol retention, better flowability (Hausner ratio decrease of 0.17) and greater yield of the powder (60%). An increase in the drying temperature (150–170 °C) caused larger particle size and improved powder flowability but also resulted in greater loss of total polyphenols. A decrease in rotary atomiser speed (11 000–15 000 rpm) had a moderate influence on particle size and improvement in flowability but had no effect on polyphenol retention. Changes in the DE (8–22) of maltodextrin as a carrier indicated a moderate growing dependence on particle size and worse flowability. 相似文献
38.
Katarzyna E. Sartowska Agnieszka Korwin‐Kossakowska Ewa Polawska Paulina Lipinska Grazyna Sender 《International Journal of Food Science & Technology》2014,49(12):2635-2642
The objective of the study was to evaluate the impact of birds’ sex on the carcass composition and meat (breast muscle) nutritional value in Japanese quails in a large‐scale four‐generation study. Standard poultry feed was used, based on maize, soya bean meal and wheat. Four generations of quails were housed up to the age of 17 weeks each. Then samples of breast muscle were collected after dissection and analysed for basic nutrient content and for fatty acids composition. Results were analysed by GLM procedure in SAS, and significance of differences between birds of different sex was estimated by Duncan's test. Dissection revealed marked differences between birds’ of different sex in case of relative organ weight. Results of meat analyses showed no differences in the basic composition. Fatty acids analyses showed a more advantageous profile in female meat. 相似文献
39.
40.
We present a review of the experimental and theoretical methods used in the discovery of new metal–hydrogen materials systems for hydrogen storage applications. Rather than a comprehensive review of all new materials and methods used in the metal hydride community, we focus on a specific subset of successful methods utilizing theoretical crystal structure prediction methods, computational approaches for screening large numbers of compound classes, and medium-throughput experimental methods for the preparation of such materials. Monte Carlo techniques paired with a simplified empirical Hamiltonian provide crystal structure candidates that are refined using density functional theory. First-principle methods using high-quality structural candidates are further screened for an estimate of reaction energetics, decomposition enthalpies, and determination of reaction pathways. Experimental synthesis utilizes a compacted-pellet sintering technique under high-pressure hydrogen at elevated temperatures. Crystal structure determination follows from a combination of Rietveld refinements of diffraction patterns and first-principles computation of total energies and dynamical stability of competing structures. The methods presented within are general and applicable to a wide class of materials for energy storage. 相似文献