全文获取类型
收费全文 | 418篇 |
免费 | 11篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 74篇 |
金属工艺 | 14篇 |
机械仪表 | 4篇 |
建筑科学 | 38篇 |
矿业工程 | 1篇 |
能源动力 | 10篇 |
轻工业 | 59篇 |
石油天然气 | 1篇 |
无线电 | 38篇 |
一般工业技术 | 58篇 |
冶金工业 | 99篇 |
原子能技术 | 3篇 |
自动化技术 | 26篇 |
出版年
2022年 | 5篇 |
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 13篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 21篇 |
2009年 | 8篇 |
2008年 | 16篇 |
2007年 | 11篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 13篇 |
2003年 | 10篇 |
2002年 | 11篇 |
2001年 | 13篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 32篇 |
1997年 | 21篇 |
1996年 | 18篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1990年 | 4篇 |
1988年 | 3篇 |
1985年 | 3篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1966年 | 3篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1963年 | 5篇 |
1956年 | 2篇 |
1929年 | 2篇 |
排序方式: 共有429条查询结果,搜索用时 15 毫秒
311.
312.
Douglas A. Spicer Thomas Astle Lisa R. Booth Russell House Karin A. Hughes Robert J. Kaiser Amy L. Springer 《Journal of The Association for Laboratory Automation》2002,7(4):50
We have developed a method for the automated purification of DNA sequencing reactions using the RapXtract™ 384 Dye Terminator Removal Kit and the Quadra 3™ Workstation. The process enables purification of 384 reactions in five minutes, significantly impacting the through-put potential of sequencing laboratories. The RapXtract technology utilizes superparamagnetic particles, (i.e., particles that are not themselves magnetic but that respond to a magnetic field) and eliminates the need for centrifugation, vacuum filtration, or modified primers. The Quadra 3 Workstation is a 384-channel liquid handling system, fitted with a retractable magnetic nest designed to incorporate a 384 magnetic separator. The combined technologies result in reduced variability associated with manual methods for sequencing reaction purification. 相似文献
313.
Andreas Springer Andreas Stelzer Robert Weigel 《e & i Elektrotechnik und Informationstechnik》2004,121(1):1-1
Ohne Zusammenfassung 相似文献
314.
R Meurer G Van Riper W Feeney P Cunningham D Hora MS Springer DE MacIntyre H Rosen 《Canadian Metallurgical Quarterly》1993,178(6):1913-1921
Equilibrium binding studies on canine mononuclear and granulocytic cells allow the identification of a single high affinity receptor for the human C-C chemokine RANTES (dissociation constant, 14 +/- 8 pM), that, in contrast to the human RANTES receptor, has no affinity for human macrophage inflammatory protein 1 alpha (hMIP-1 alpha). A single intradermal injection of hRANTES in dog resulted in eosinophil- and macrophage-rich inflammatory sites within 4 h. Cell infiltration peaked at 16-24 h after hRANTES injection. There was histological evidence of intravascular activation of eosinophils at 4 h, although eosinophils in the vasculature and interstitium contained apparently intact granules. Monocytes were the predominant cells adherent to venular endothelium at 16-24 h. Human MIP-1 alpha elicited no response in canine dermis, whereas monocyte chemoattractant protein 1 caused mild perivascular cuffing with monocytes. In contrast, human interleukin 8 induced a neutrophilic dermal infiltrate that was maximal by 4 h after challenge. This provides the first direct evidence in vivo that RANTES has significant proinflammatory activity and, in addition, could be a mediator in atopic pathologies characterized by eosinophilic and monocytic inflammatory responses. 相似文献
315.
Representatives of the family Methanosarcinaceae were analyzed phylogenetically by comparing partial sequences of their methyl-coenzyme M reductase (mcrI) genes. A 490-bp fragment from the A subunit of the gene was selected, amplified by the PCR, cloned, and sequenced for each of 25 strains belonging to the Methanosarcinaceae. The sequences obtained were aligned with the corresponding portions of five previously published sequences, and all of the sequences were compared to determine phylogenetic distances by Fitch distance matrix methods. We prepared analogous trees based on 16S rRNA sequences; these trees corresponded closely to the mcrI trees, although the mcrI sequences of pairs of organisms had 3.01 +/- 0.541 times more changes than the respective pairs of 16S rRNA sequences, suggesting that the mcrI fragment evolved about three times more rapidly than the 16S rRNA gene. The qualitative similarity of the mcrI and 16S rRNA trees suggests that transfer of genetic information between dissimilar organisms has not significantly affected these sequences, although we found inconsistencies between some mcrI distances that we measured and and previously published DNA reassociation data. It is unlikely that multiple mcrI isogenes were present in the organisms that we examined, because we found no major discrepancies in multiple determinations of mcrI sequences from the same organism. Our primers for the PCR also match analogous sites in the previously published mcrII sequences, but all of the sequences that we obtained from members of the Methanosarcinaceae were more closely related to mcrI sequences than to mcrII sequences, suggesting that members of the Methanosarcinaceae do not have distinct mcrII genes. 相似文献
316.
Using pre-etchings containing chromium trioxide, phosphoric acid, and sulphuric acid the residual compounds of chromium, phosphor, and sulphur are tied irreversibly on the surface of polypropylene and ethylene-propylene-copolymers. The staying depends on the morphology of the polymer surface and obtains first maxima after short times of etching. The covering of the polymers influences the peel strength of the galvanically deposited metal layer. Residual sulphuric compounds have a stronger influence than phosphoric compounds. Residual chromium compounds exert no effect on the peel strength. 相似文献
317.
The structure of a 15–20 μm thick copper layer, which is deposited electrochemically on copolymers of acrylonitrile, butadiene and styrene from bathes containing additives is extremely distorted. This is caused by microstresses and paracrystalline lattice distortions. On the other hand, the structure of the copper layer deposited from a pure bath is independent of the chemical pre-conditioning of the polymer surface, necessary for plating, and equal to that of a high crystalline pure copper. 相似文献
318.
Dipl.-Ing. Dr. Helmut Springer 《Forschung im Ingenieurwesen》1979,45(4):119-132
Zusammenfassung Ein vom Autor angegebenes N?herungsverfahren zur ?konomischen Berechnung hydrodynamischer Lager wird benutzt, um nichtlineare
und instation?re Schwingungen von Vertikalrotoren für gro?e Schwingungsamplituden in den Radialführungslagern zu untersuchen.
Das reale Rotorsystem wird mit Hilfe balkenf?rmiger finiter Elemente angen?hert. Statische und dynamische Unwuchten der Rotormassen,
gyroskopische Effekte, die Wirkung magnetischer Zugkr?fte und viskoser D?mpfungskr?fte werden berücksichtigt. Die nichtlinearen
Lagerkr?fte in den Kippsegmentradiallagern berechnen sich durch L?sung der instation?ren Reynolds-Gleichung für jedes einzelne
Kippsegment unter Berücksichtigung der Segmentmassentr?gheit und der Nachgiebigkeit der Segmentunterstützung in der elastischen
Lagerkonstruktion. In einem Berechnungsbeispiel wird ein Vertikalrotor mit 28 Freiheitsgraden untersucht. Die instation?ren
Schwingungen des Rotor- und Lagersystems zufolge radialer Sto?erregung oder pl?tzlich auftretender Unwuchten werden berechnet
und die nichtlinearen Einflüsse diskutiert. Für harmonisch verlaufende Lagerkr?fte wird schlie?lich die dynamische Lagersteifigkeit
am Beispiel eines zw?lfsegmentigen Führungslagers als Funktion der Wellenschwingungsamplitude ermittelt.
Herrn Professor Dr.Heinz Parkus zur Vollendung seines 70. Lebensjahres gewidmet 相似文献
319.
A semi‐analytical curved element for linear elasticity based on the scaled boundary finite element method
下载免费PDF全文
![点击此处可从《International journal for numerical methods in engineering》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fabian Krome Hauke Gravenkamp 《International journal for numerical methods in engineering》2017,109(6):790-808
This work introduces a semi‐analytical formulation for the simulation and modeling of curved structures based on the scaled boundary finite element method (SBFEM). This approach adapts the fundamental idea of the SBFEM concept to scale a boundary to describe a geometry. Until now, scaling in SBFEM has exclusively been performed along a straight coordinate that enlarges, shrinks, or shifts a given boundary. In this novel approach, scaling is based on a polar or cylindrical coordinate system such that a boundary is shifted along a curved scaling direction. The derived formulations are used to compute the static and dynamic stiffness matrices of homogeneous curved structures. The resulting elements can be coupled to general SBFEM or FEM domains. For elastodynamic problems, computations are performed in the frequency domain. Results of this work are validated using the global matrix method and standard finite element analysis. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
320.
MS Springer A Burk JR Kavanagh VG Waddell MJ Stanhope 《Canadian Metallurgical Quarterly》1997,94(25):13754-13759
The subclass Theria of Mammalia includes marsupials (infraclass Metatheria) and placentals (infraclass Eutheria). Within each group, interordinal relationships remain unclear. One limitation of many studies is incomplete ordinal representation. Here, we analyze DNA sequences for part of exon 1 of the interphotoreceptor retinoid binding protein gene, including 10 that are newly reported, for representatives of all therian orders. Among placentals, the most robust clades are Cetartiodactyla, Paenungulata, and an expanded African clade that includes paenungulates, tubulidentates, and macroscelideans. Anagalida, Archonta, Altungulata, Hyracoidea + Perissodactyla, Ungulata, and the "flying primate" hypothesis are rejected by statistical tests. Among marsupials, the most robust clade includes all orders except Didelphimorphia. The phylogenetic placement of the monito del monte and the marsupial mole remains unclear. However, the marsupial mole sequence contains three frameshift indels and numerous stop codons in all three reading frames. Given that the interphotoreceptor retinoid binding protein gene is a single-copy gene that functions in the visual cycle and that the marsupial mole is blind with degenerate eyes, this finding suggests that phenotypic degeneration of the eyes is accompanied by parallel changes at the molecular level as a result of relaxed selective constraints. 相似文献