全文获取类型
收费全文 | 1666篇 |
免费 | 65篇 |
专业分类
电工技术 | 23篇 |
综合类 | 2篇 |
化学工业 | 303篇 |
金属工艺 | 31篇 |
机械仪表 | 35篇 |
建筑科学 | 65篇 |
矿业工程 | 7篇 |
能源动力 | 50篇 |
轻工业 | 86篇 |
水利工程 | 14篇 |
石油天然气 | 3篇 |
无线电 | 217篇 |
一般工业技术 | 335篇 |
冶金工业 | 276篇 |
原子能技术 | 16篇 |
自动化技术 | 268篇 |
出版年
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 25篇 |
2020年 | 15篇 |
2019年 | 29篇 |
2018年 | 33篇 |
2017年 | 30篇 |
2016年 | 41篇 |
2015年 | 35篇 |
2014年 | 47篇 |
2013年 | 90篇 |
2012年 | 65篇 |
2011年 | 106篇 |
2010年 | 71篇 |
2009年 | 103篇 |
2008年 | 62篇 |
2007年 | 80篇 |
2006年 | 80篇 |
2005年 | 72篇 |
2004年 | 61篇 |
2003年 | 32篇 |
2002年 | 50篇 |
2001年 | 31篇 |
2000年 | 31篇 |
1999年 | 32篇 |
1998年 | 68篇 |
1997年 | 60篇 |
1996年 | 42篇 |
1995年 | 31篇 |
1994年 | 29篇 |
1993年 | 22篇 |
1992年 | 16篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 22篇 |
1988年 | 17篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 10篇 |
1976年 | 19篇 |
1975年 | 3篇 |
1971年 | 3篇 |
1964年 | 3篇 |
排序方式: 共有1731条查询结果,搜索用时 15 毫秒
1.
J Stagsted S Ziebe S Satoh GD Holman SW Cushman L Olsson 《Canadian Metallurgical Quarterly》1993,268(3):1770-1774
Peptides derived from the alpha 1-region of the murine H-2Dk molecule enhance glucose uptake in rat adipose cells above the maximum obtained with insulin stimulation alone (Stagsted, J., Reaven, G. M., Hansen, T., Goldstein, A., and Olsson, L. (1990) Cell 62, 297-307). We now describe that epidermal growth factor (EGF) in combination with the same peptides, Dk-(61-85) and Dk-(62-85), stimulates cellular glucose uptake 5-7 times over the basal level, i.e. to 30-50% of the maximal insulin effect. EGF alone increased glucose uptake by only approximately 50% above basal and the peptide alone by 100% above basal. Maximal effect of EGF and peptide was reached in 10-20 min with 30 microM peptide (EC50 10-15 microM) and 50 nM EGF (EC50 1-2 nM). The effect of EGF and peptide on glucose uptake was additive to that of insulin and peptide until the maximal level attained with insulin and peptide was reached. The combined effect of EGF plus peptide on glucose transport was associated with a recruitment of GLUT4 molecules to the plasma membrane. However, the phosphatidylinositol (PI) kinase which is activated by insulin was not activated by EGF plus peptide. Thus, the effect of EGF plus peptide on glucose uptake seems independent of the activity status of the insulin receptor. 125I-Labeled EGF bound specifically to rat adipose cells with an apparent affinity of approximately 2 nM and Bmax approximately 5 x 10(3). However, the major histocompatibility complex (MHC) peptides did not affect EGF-stimulated internalization of EGF receptor, in contrast to their effect on the insulin receptors. Transforming growth factor alpha had an effect similar to EGF on glucose uptake. Three other peptides derived from other parts of murine MHC class I had no effect on glucose uptake in combination with EGF. Thus, EGF in combination with certain MHC class I-derived peptides is insulinomimetic concerning glucose transport and this effect is independent of the insulin receptor activity. 相似文献
2.
This article describes a study of delamination growth along 0 °/0 °, 0 °/ 5 °, ± 5 °, and 0 °/90 ° interfaces sandwiched between unidirectional carbon fibre/epoxy composite material. Relationships between damage criticality, growth rate and acoustic emission activity for delamination growth have been studied and the transferability of results from laboratory coupons to composite structural elements has been examined. Two types of coupon tests, conventional delamination beams and rigidly loaded single edge notched strips, have been compared for different mode ratios. Comparative tests have been made on buckling-induced delamination in plates. A graphite crack gauge has been used to measure delamination length and growth rate, ranging from 0.05–2000 m/s. Damage growth was also followed using visual, ultrasonic C-scan, X-ray radiography, macro-video and acoustic emission measurements. Empirical evaluations of interlaminar toughness for delamination beams are made using the Irwin-Kies relation. Unstable growth is analysed using elasto-dynamic moving finite elements. Bucklinginduced delamination is analysed using plate/shell FE methods with growth/remeshing algorithms. 相似文献
3.
T. Torounidis M. Westlund H. Sunnerud B.-E. Olsson P.A. Andrekson 《Photonics Technology Letters, IEEE》2005,17(2):312-314
Short return-to-zero pulses (/spl sim/2 ps) are generated at bit rates of 40, 80, and 160 Gb/s using a fiber-optical parametric amplifier. The performance of the parametric pulse source is evaluated both back-to-back and in a 110-km transmission link. A receiver sensitivity of -33 dBm back-to-back was achieved after demultiplexing from 160 to 10 Gb/s. The power penalty at 160 Gb/s due to 110-km transmission was less than 2 dB. Very short pulses (0.5 ps) were also achieved when using the parametric amplifier as a compressor. 相似文献
4.
Magnus Rnning Florian Huber Hilde Meland Hilde Venvik De Chen Anders Holmen 《Catalysis Today》2005,100(3-4):249-254
In order to investigate the effect of cerium oxide on Cu–Zn-based mixed-oxide catalysts four catalyst samples were characterized by means of XRD, in situ XANES and thermogravimetric analysis. The activity of the catalyst samples was tested for the forward water–gas shift reaction. Cerium oxide was found to increase the crystallinity of the ZnO phase indicating a segregation of the Cu and ZnO phases. The TOF of the water–gas shift reaction based on chemisorption data was found to be independent of composition and preparation conditions of the four catalyst samples. In contrast, the catalyst stability depends on composition and preparation conditions. Cerium oxide impregnated before calcination of the hydrotalcite-based Cu–Zn precursors leads to a more stable water–gas shift catalyst. 相似文献
5.
Magnus Fredriksson Niels Saabye Ottosen 《International journal for numerical methods in engineering》2004,61(11):1809-1834
An accurate and variationally consistent 4‐node quadrilateral element is introduced where high coarse mesh accuracy and low mesh distortion sensitivity are characteristic qualities, even when incompressibility is approached for plane strain. One‐point quadrature integration procedure is adopted and a new improved stabilization technique is developed. Orthogonality conditions are utilized so that the patch test is satisfied for arbitrary quadrilaterals. Several numerical examples including a convergence rate study are presented which confirm the excellent performance of this element. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
6.
Two Ghanaian women, aged 21 and 29 years, who were involved in road traffic accidents sustaining blunt trauma to the chest and who had delayed diagnosis of their total bronchial rupture and underwent successful surgical repair 18 and 29 months, respectively after injury are reported with a review of the literature. We believe these to be the first reported cases of delayed diagnosis and successful repair of total bronchial rupture in Tropical Africa. 相似文献
7.
8.
Retrospectively 78 patients with uni- or bilateral acute acoustic trauma (AAT) were evaluated to assess the therapeutic effect of hyperbaric oxygenation (HBO). All subjects received saline or dextran (Rheomacodrex) infusions with Ginkgo extracts (Tebonin) and prednisone. Thirty six patients underwent additional hyperbaric oxygenation at a pressure of 2 atmospheres absolute for 60 minutes once daily. Both treatment groups were comparable as far as age, gender, initial hearing loss and prednisone dose are concerned. The delay of therapy onset was 15 hours in both groups and treatment was started within 72 hours in all cases. Control audiometry was performed after 6.5 days, when the HBO group had had 5 exposures to hyperbaric oxygenation. The average hearing gain in the group without HBO was 74.3 dB and in the group treated additionally with HBO 121.3 dB (P < 0.004). It is concluded, that hyperbaric oxygenation significantly improves hearing recovery after AAT. Therefore acute acoustic trauma with significant hearing threshold depression remains an otological emergency. Minimal therapy involving waiting for spontaneous recovery, which is mostly incomplete leaving a residual C5 or C6 and handicapping tinnitus, is not the treatment of choice. Randomized prospective clinical trials with a larger patient series are needed and further experimental studies are required to understand the physiological mechanisms of HBO responsible for the clinical success in AAT. 相似文献
9.
During the last 15 years cycles with CO2 capture have been in focus, due to the growing concern over our climate. Often, a natural gas fired combined cycle with a chemical absorption plant for CO2 capture from the flue gases have been used as a reference in comparisons between cycles. Neither the integration of the steam production for regeneration of amines in the combined cycle nor the off-design behaviour of such a plant has been extensively studied before. 相似文献
10.
Aseel Berglund Erik Berglund Anders Larsson Magnus Bang 《Universal Access in the Information Society》2006,4(4):300-327
The television (TV) is one of the most common entertainment devices in homes. Searching and finding TV programs is a common task and using TV guides is one way of performing this. This paper presents three studies that are focused on examining audiences’ TV habits and TV guide usage, evaluating a new concept based on linking paper and pen with TV technology, and studying the audiences’ attitudes toward and anticipated interest in the future guide. The results of our first study emphasize the value of using paper based TV guides and also identify the deficiencies. We also found indications that the advantages and disadvantages of paper-based TV guides are related to the physical properties of paper. Thus, we suggest a solution that uses digital pen and paper technology to offer a new interaction method for TV. A research system “Paper Remote”, is developed and used in the two subsequent studies. Viewers tick designated areas on the paper-based guide to perform actions such as channel switching. However, this solution is not a substitute for the remote control device. We argue that these user studies on linking digital paper to the TV for everyday information navigation illuminate the possibilities of providing innovative solutions also for home information systems also. 相似文献