全文获取类型
收费全文 | 3542篇 |
免费 | 214篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 58篇 |
综合类 | 14篇 |
化学工业 | 731篇 |
金属工艺 | 70篇 |
机械仪表 | 69篇 |
建筑科学 | 192篇 |
矿业工程 | 4篇 |
能源动力 | 104篇 |
轻工业 | 368篇 |
水利工程 | 30篇 |
石油天然气 | 24篇 |
无线电 | 303篇 |
一般工业技术 | 597篇 |
冶金工业 | 475篇 |
原子能技术 | 35篇 |
自动化技术 | 685篇 |
出版年
2023年 | 54篇 |
2022年 | 80篇 |
2021年 | 117篇 |
2020年 | 58篇 |
2019年 | 68篇 |
2018年 | 80篇 |
2017年 | 83篇 |
2016年 | 127篇 |
2015年 | 118篇 |
2014年 | 132篇 |
2013年 | 208篇 |
2012年 | 185篇 |
2011年 | 237篇 |
2010年 | 222篇 |
2009年 | 165篇 |
2008年 | 178篇 |
2007年 | 150篇 |
2006年 | 153篇 |
2005年 | 123篇 |
2004年 | 105篇 |
2003年 | 77篇 |
2002年 | 87篇 |
2001年 | 73篇 |
2000年 | 51篇 |
1999年 | 75篇 |
1998年 | 141篇 |
1997年 | 79篇 |
1996年 | 60篇 |
1995年 | 55篇 |
1994年 | 35篇 |
1993年 | 42篇 |
1992年 | 21篇 |
1991年 | 20篇 |
1990年 | 19篇 |
1989年 | 29篇 |
1988年 | 21篇 |
1987年 | 19篇 |
1986年 | 13篇 |
1985年 | 27篇 |
1984年 | 11篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1977年 | 10篇 |
1976年 | 28篇 |
1975年 | 6篇 |
1973年 | 7篇 |
1971年 | 6篇 |
1968年 | 6篇 |
排序方式: 共有3759条查询结果,搜索用时 57 毫秒
1.
Michael Lommel Vera Froese Moritz Sieber Marvin Jentzsch Tim Bierewirtz Ümit Hasirci Tim Rese Josef Seefeldt Sebastian Schimek Ulrich Kertzscher Christian Oliver Paschereit 《Indoor air》2021,31(6):1860-1873
The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier. 相似文献
2.
3.
Dr. Blijke S. Kroezen Gabriele Conti Benedetta Girardi Dr. Jonathan Cramer Dr. Xiaohua Jiang Dr. Said Rabbani Jennifer Müller Maja Kokot Enrico Luisoni Prof. Daniel Ricklin Dr. Oliver Schwardt Prof. Beat Ernst 《ChemMedChem》2020,15(18):1706-1719
Siglecs are members of the immunoglobulin gene family containing sialic acid binding N-terminal domains. Among them, Siglec-8 is expressed on various cell types of the immune system such as eosinophils, mast cells and weakly on basophils. Cross-linking of Siglec-8 with monoclonal antibodies triggers apoptosis in eosinophils and inhibits degranulation of mast cells, making Siglec-8 a promising target for the treatment of eosinophil- and mast cell-associated diseases such as asthma. The tetrasaccharide 6’-sulfo-sialyl Lewisx has been identified as a specific Siglec-8 ligand in glycan array screening. Here, we describe an extended study enlightening the pharmacophores of 6’-sulfo-sialyl Lewisx and the successful development of a high-affinity mimetic. Retaining the neuraminic acid core, the introduction of a carbocyclic mimetic of the Gal moiety and a sulfonamide substituent in the 9-position gave a 20-fold improved binding affinity. Finally, the residence time, which usually is the Achilles tendon of carbohydrate/lectin interactions, could be improved. 相似文献
4.
Bart J Kemps Flip R Bamelis Bart De Ketelaere Kristof Mertens Kokou Tona Eddy M Decuypere Josse G De Baerdemaeker 《Journal of the science of food and agriculture》2006,86(9):1399-1406
The objective of this research was to investigate the feasibility of visible transmission spectroscopy for the non‐destructive assessment of the freshness of an individual egg. A total of 600 intact white‐shelled eggs of the same flock (Lohmann, 40 weeks of age) were measured. To obtain a considerable variation in freshness, groups consisting of 60 eggs were stored (18 °C, 55% RH) for 0, 2, 4, 6, 8, 10, 12, 14, 16 and 18 days. The non‐destructive spectral measurements were compared with the two most widely used destructive freshness parameters, namely Haugh units and albumen pH. A partial least squares (PLS1) model was built in order to predict Haugh units and pH of the albumen based on the transmission spectra. The correlation coefficients between the predicted value and the measured value were 0.842 and 0.867 for Haugh unit and pH of the albumen, respectively. These results show that the light transmission spectrum of an egg provides quantitative information about egg freshness. Relevant information concerning egg freshness is restricted to the interval between 570 and 750 nm. Furthermore, the models obtained for both destructive parameters were strikingly similar, indicating that Haugh unit and pH have the same physico‐chemical background. Copyright © 2006 Society of Chemical Industry 相似文献
5.
van Dick Rolf; Wagner Ulrich; Pettigrew Thomas F.; Christ Oliver; Wolf Carina; Petzel Thomas; Castro Vanessa Smith; Jackson James S. 《Canadian Metallurgical Quarterly》2004,87(2):211
Furthering G. W. Allport's (1954) contentions for optimal contact, the authors introduce a new construct: the perceived importance of contact. They propose that perceived importance is the best proximal predictor of contact's reduction of prejudice. If individuals have opportunities for contact at work or in the neighborhood, their chances to have intergroup acquaintances and friends increase. Intergroup contact among acquaintances and friends can be perceived as more or less important, which in turn determines intergroup evaluations. A 1st study shows that the new measure of perceived importance is indeed distinct from established quantity and quality indicators. The results are cross-validated in a 2nd study that also sheds light on the meaning of importance. In 3rd and 4th studies, structural equation analyses and a meta-analysis support the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
A. Alt Dr.‐Ing. H. Mertens U. Arz L. Blessing C. Berger 《Materialwissenschaft und Werkstofftechnik》2007,38(5):402-409
High cycle fatigue of bolted connections Extensive tests regarding the influences on the fatigue of bolt‐nut‐connections of preloading with torsion, of preloading with yielding, of loading with superimposed bending and of the tested lot are processed. These influences are not yet known according to VDI 2230. New testing devices were designed for these tests, which allow a far less expensive operation and may easily be used for bolts of diameters up to M100 and testing frequencies up to 1000 Hz. The validity of fatigue resistance according to VDI 2230 is specified with respect to the test results. The determined influence of the tested lots is unexpectedly high. The manufacturing process of bolts should be improved to minimize this influence. 相似文献
8.
9.
10.