全文获取类型
收费全文 | 807篇 |
免费 | 64篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 12篇 |
综合类 | 2篇 |
化学工业 | 193篇 |
金属工艺 | 15篇 |
机械仪表 | 40篇 |
建筑科学 | 20篇 |
能源动力 | 37篇 |
轻工业 | 90篇 |
水利工程 | 9篇 |
石油天然气 | 9篇 |
无线电 | 67篇 |
一般工业技术 | 164篇 |
冶金工业 | 104篇 |
原子能技术 | 8篇 |
自动化技术 | 104篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 34篇 |
2020年 | 28篇 |
2019年 | 33篇 |
2018年 | 34篇 |
2017年 | 38篇 |
2016年 | 37篇 |
2015年 | 26篇 |
2014年 | 36篇 |
2013年 | 67篇 |
2012年 | 39篇 |
2011年 | 57篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 45篇 |
2007年 | 27篇 |
2006年 | 22篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 13篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 17篇 |
1998年 | 29篇 |
1997年 | 13篇 |
1996年 | 18篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有874条查询结果,搜索用时 15 毫秒
71.
V.A.F. Costa F. Neto da Silva 《International Journal of Heat and Mass Transfer》2003,46(19):3717-3726
The concept of inversion temperature was developed in order to assess the effectiveness of superheated steam as a drying agent when compared with dry or humid air above a given temperature. The inversion temperature can be defined in different ways, for different physical situations, thus leading to strong discrepancies between its reported numerical values. A clear understanding of such definitions and its consequences over the inversion temperature values is of major importance, as well as the way to estimate the inversion temperature of interest for a given practical evaporation process. Analytical expressions are proposed for some possible definitions of the inversion temperature. Special emphasis is devoted to the physical reasoning on the existence of the inversion temperature and how its value is affected by other variables such as humidity level, mass flow rate and geometry of the evaporative system. 相似文献
72.
The use of X-ray diffraction, microscopy, and magnetic measurements for analysing microstructural features of a duplex stainless steel 总被引:1,自引:0,他引:1
M.A. Ribeiro Miranda J.M. Sasaki S.S.M. Tavares H.F.G. de Abreu J.M. Neto 《Materials Characterization》2005,54(4-5):387-393
X-ray diffraction, light optical microscopy, and magnetization saturation measurements were employed to analyse the microstructural features of a UNS S31803 duplex stainless steel modified by high-temperature treatments. The samples were heated to 1300 °C and cooled by different ways to produce five different microstructures. Solution treatments at 1000 °C were also employed to produce another five conditions. Three methods were employed to determine the austenite/ferrite proportions. X-ray diffraction gave higher austenite values than the other methods, due to the influence of texture, but can be successfully used to determine the microstrain level in each phase. Magnetic saturation measurement is a very simple and precise method for quantification of austenite and ferrite volume fractions in samples that were fast-cooled and slow-cooled. Light microscopy can give a fast and precise measurement of the phase proportions and reveals important features related to the morphology of the phases, but in the samples where the austenite content is low, quantification becomes difficult and imprecise. 相似文献
73.
Renata Braga Araújo Guilherme Henrique Trielli Ferreira Gustavo Henrique Orair Wagner Meira Jr. Renato Antônio Celso Ferreira Dorgival Olavo Guedes Neto Mohammed Javeed Zaki 《International journal of parallel programming》2008,36(2):226-249
Analyzing gene expression patterns is becoming a highly relevant task in the Bioinformatics area. This analysis makes it possible
to determine the behavior patterns of genes under various conditions, a fundamental information for treating diseases, among
other applications. A recent advance in this area is the Tricluster algorithm, which is the first algorithm capable of determining
3D clusters (genes × samples × timestamps), that is, groups of genes that behave similarly across samples and timestamps.
However, even though biological experiments collect an increasing amount of data to be analyzed and correlated, the triclustering
problem remains a bottleneck due to its NP-Completeness, so its parallelization seems to be an essential step towards obtaining
feasible solutions. In this work we propose and evaluate the implementation of a parallel version of the Tricluster algorithm
using the filter-labeled-stream paradigm supported by the Anthill parallel programming environment. The results show that
our parallelization scales well with the data size, being able to handle severe load imbalances that are inherent to the problem.
Further more, the parallelization strategy is applicable to any depth-first searches. 相似文献
74.
EP Souza Neto PG Durand F Sassolas C Vial JJ Lehot 《Canadian Metallurgical Quarterly》1998,42(7):876-879
The arm is particularly vulnerable to neurological injury, due to the intimate anatomical relationship between the brachial plexus and the traction zones. Severe injuries of the brachial plexus can be caused by compression, traction or laceration. Fortunately, many deficits are superficial and permanent neurovascular deficits are rare. Nevertheless, it is important to identify the probable cause of the injury since the prognosis for recovery directly depends on the underlying nature of the neurological deficit. Two anaesthetised children who suffered brachial plexus injury during cardiac catheterisation are reported. The first, with Ebstein's anomaly and significant pulmonary valve stenosis, presented, after the procedure, with a right arm motor deficit with proximal predominance. The second patient, with tetralogy of Fallot and pulmonary atresia, presented difficulty in left arm abduction and external rotation on awakening. The risk factors for brachial plexus lesions during anaesthesia are discussed. These include improper positioning, anaesthetic agents, extreme variations of body mass index and anatomical anomalies. Prevention, evolution and treatment of the brachial plexus injury are also considered. With proper care by the cardio-radiologist and anaesthesiologist the frequency of this injury can be reduced. 相似文献
75.
A mixed lumped-differential formulation for double-pipe heat exchangers is presented that radially lumps the temperature distribution in the outer channel, providing a differential problem for the inner channel that involves a more general type of boundary condition for the wall temperature. The generalized integral transform technique is extended to allow for the analytical solution of this class of problems. Applicability limits for the simplified model are then established in terms of related parameters, based on numerical results obtained for bulk temperatures and Nusselt numbers, as compared to more involved approaches for the complete differential model. 相似文献
76.
The use of the long palmar muscle in surgeries of muscular transposition and transplantation in orthopedic and plastic surgeries has encouraged the investigation of arterial branches for the long palmar muscle. This study was carried out in 58 upper limbs of child cadavers aged up to one year. It was observed that the muscle was not present in 31.04% of the forearms. It more frequently presents one to two arterial branches which arise mainly, from the ulnar artery (85.71%) and less frequently from brachial artery (22.86%). The arterial branches penetrate the muscle through the posterior face, 62.71% being at the proximal third and 33.90% at the medium third. The most frequent models of the branch disposition were from one to two branches of the ulnar artery which penetrate the proximal thirds (28.57%) and two branches of the ulnar artery, the median and proximal thirds, respectively (17.14%). 相似文献
77.
Using Bulk Built-in Current Sensors to Detect Soft Errors 总被引:2,自引:0,他引:2
Connecting a built-in current sensor in the design bulk of a digital system increases sensitivity for detecting transient upsets in combinational and sequential logic. SPICE simulations validate this approach and show only minor penalties in terms of area, performance, and power consumption 相似文献
78.
The (1–3, 1–4)‐β‐Glucanases in Malting Barley: Enzyme Survival and Genetic and Environmental Effects
J.E. Georg‐Kraemer E. Caiero E. Minella J.F. Barbosa‐Neto S.S. Cavalli 《Journal of the Institute of Brewing》2004,110(4):303-308
Eighteen barley genotypes used in Brazilian malting barley breeding programs were characterized in relation to (1–3, 1–4)‐β‐glucanase activity in green and kilned malt. They were tested to determine the loss of enzyme activity during kilning in the malting process and the environmental effects on enzyme activity were measured. The genotypes analyzed showed great variation regarding the enzyme activity in both kinds of malt, in a range from 531.94 to 934.31 U/kg in green malt, and from 187.02 to 518.40 U/kg in dry malt. The mean enzyme activity loss during kilning was close to 60%, very similar to the results obtained in other studies. The loss among genotypes varied from 8.04% to 71.54%. The enzyme activity varied significantly under the different environments tested, showing existence of environmental effects on the genotypes analyzed. Embrapa 127 was the genotype that exhibited the highest enzyme activity in finished malt although it had shown a low activity in green malt, reflecting a negligible loss of activity during kilning. The data indicate promising results to malting barley breeding due to the wide variability exhibited by genotypes as to enzyme activity and levels of isoenzyme with high thermostability. 相似文献
79.
80.