全文获取类型
收费全文 | 941篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 41篇 |
金属工艺 | 9篇 |
机械仪表 | 8篇 |
建筑科学 | 24篇 |
矿业工程 | 2篇 |
能源动力 | 6篇 |
轻工业 | 23篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 100篇 |
一般工业技术 | 74篇 |
冶金工业 | 574篇 |
原子能技术 | 8篇 |
自动化技术 | 74篇 |
出版年
2021年 | 6篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 20篇 |
2012年 | 10篇 |
2011年 | 20篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 24篇 |
2006年 | 12篇 |
2005年 | 19篇 |
2004年 | 14篇 |
2003年 | 17篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 16篇 |
1999年 | 29篇 |
1998年 | 172篇 |
1997年 | 101篇 |
1996年 | 74篇 |
1995年 | 40篇 |
1994年 | 35篇 |
1993年 | 38篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 30篇 |
1976年 | 31篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 3篇 |
1928年 | 1篇 |
排序方式: 共有957条查询结果,搜索用时 15 毫秒
61.
DV Stambolsky YS Kuzmenko MP Philippova VN Bochkov ZD Bespalova AA Azmuko NM Kashirina TN Vlasik VA Tkachuk TJ Resink 《Canadian Metallurgical Quarterly》1999,1416(1-2):155-160
Atypical cell surface lipoprotein-binding proteins of 105 kDa and 130 kDa are present in membranes of vascular smooth muscle cells. We recently identified the 105 kDa protein from human aortic media as T-cadherin, an unusual glycosylphosphatidylinositol (GPI)-anchored member of the cadherin family of cell adhesion proteins. The goal of the present study was to determine the identity of 130 kDa lipoprotein-binding protein of smooth muscle cells. We applied different approaches that included protein sequencing of purified protein from human aortic media, the use of human T-cadherin peptide-specific antisera, and enzymatic treatment of cultured cells with trypsin and GPI-specific phospholipase C. Our results indicate that the 130 kDa protein is a partially processed form of T-cadherin which is attached to the membrane surface of smooth muscle cells via a GPI anchor and contains uncleaved N-terminal propeptide sequence. Our data disclose that, in contrast to classical cadherins, T-cadherin is expressed on the cell surface in both its precursor (130 kDa) and mature (105 kDa) forms. 相似文献
62.
The dawn of organic electronics 总被引:1,自引:0,他引:1
Organic semiconductors are poised to transform the world of circuit and display technology. Major electronics firms such as Philips and Pioneer, and smaller companies such as Cambridge Display Technology, Universal Display, and Uniax, are betting that the future holds tremendous opportunity for the low cost and sometimes surprisingly high performance offered by organic electronic and optoelectronic devices. Using organic light-emitting devices (OLEDs), organic full-color displays may eventually replace liquid-crystal displays (LCDs) for use with laptop and even desktop computers. Such displays can be deposited on flexible plastic foils, eliminating the fragile and heavy glass substrates used in LCDs, and can emit bright light without the pronounced directionality inherent in LCD viewing, all with efficiencies higher than can be obtained with incandescent light bulbs 相似文献
63.
A. L. Forrest K. P. Fattah D. S. Mavinic F. A. Koch 《Canadian Metallurgical Quarterly》2008,134(5):395-402
Struvite, a crystalline structure comprised of ions of magnesium (Mg+2), ammonium (NH4–N), and phosphate (PO4–P), is commonly encountered in wastewater treatment plants (WWTPs) through struvite encrustation. The gradual accumulation of this crystal in pipes and fittings leads to high costs due to downtime and replacement of parts. Technologies that are used to reduce this problem are ideally located in biological nutrient removal plants downstream of anaerobic digesters, as high levels of NH4–N and PO4–P typically characterize anaerobic digester supernatants. In 2003–2004, two technical-scale, struvite recovery studies were conducted on-site at the City of Penticton, B.C., Canada and the City of Richmond, B.C., Canada using a novel technology developed by the environmental engineering group at the University of British Columbia. The results of these studies showed an average reduction of 80% in phosphate and a dense, spherical product, 5–10 times larger than any commercially available struvite to date. Overall, the recovery of struvite has enormous commercial potential, which results in WWTP becoming more sustainable, concurrently reducing problems typically associated with their operation. 相似文献
64.
65.
Daly Raymond M.; Holland Cornelius J.; Forrest Patricia A.; Fellbaum G. Anthony 《Canadian Metallurgical Quarterly》1985,17(4):379
Assessed the permanence of the treatment effects (temporal generalization) obtained by a parent-training program, Directive Parental Counseling (DPC), developed by the 2nd author (1983). 20 parents who participated in the program completed the Walker Problem Behavior Identification Checklist and the Missouri Children's Behavior Checklist at pretreatment, treatment termination, 3 mo posttreatment, and 3 yrs posttreatment. The parents were part of a larger treatment group of 36 Ss who demonstrated superiority in altering targeted behaviors of their children (mean age 6 yrs 11 mo), in contrast to a waiting-control group, at the completion of a 10-wk program. The positive changes noted on the behavior rating scales obtained from the parents in the treatment group at the posttreatment period were still evident at the 3-mo follow-up and continued to increase over the 3-yr interval. Results are discussed in light of the issues surrounding temporal generalization and the structure of the DPC program. (French abstract) (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Beutler Larry E.; Scogin Forrest; Kirkish Patricia; Schretlen David; Corbishley Anne; Hamblin David; Meredith Keith; Potter Rebecca; Bamford Colin R.; Levenson Alan I. 《Canadian Metallurgical Quarterly》1987,55(4):550
This study was designed to explore the relative and combined effectiveness of alprazolam (Xanax) and group cognitive therapy among elderly adults experiencing major affective disorder. Fifty-six subjects with Diagnostic and Statistical Manual of Mental Disorders (DSM-III) diagnoses of major, unipolar depression were treated over a 20-week period in one of four groups: alprazolam support, placebo support, cognitive therapy plus placebo support, and cognitive therapy plus alprazolam support. The results revealed that individuals assigned to group cognitive therapy showed consistent improvement in subjective state and sleep efficiency relative to non-group-therapy subjects. No differences between alprazolam and placebo were noted, regardless of whether individuals received group cognitive therapy. Subjects assigned to group cognitive therapy were less likely than their counterparts to prematurely terminate treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
67.
A geological database comprising coregistered Landsat Thematic Mapper (TM) regional multielement stream sediment geochemistry, regional gravity and aeromagnetics, and geological map data has been established, in raster format, for the area of the English Lake District. To study spatial correlations within the database, TM imagery and its first-order structurally enhanced filter derivatives are combined with regional survey data using intensity-hue-saturation transforms and stereoscopic-view generation techniques. These are then overlaid with line and polygon information from other exploration datasets. Datasets are combined in a manner which maintains the identity of each dataset. The imagery produced demonstrates the power of image presentation for efficient multidata analysis.<> 相似文献
68.
Brown J.J. Lo D.C.W. Gardner J.T. Chung Y.K. Lee C.D. Forrest S.R. 《Electron Device Letters, IEEE》1989,10(12):588-590
In0.53Ga0.47As active feedback junction field-effect transistors (JFETs) for use in integrated transimpedance photoreceivers are discussed. By varying the gate-to-source voltage V GS, the resistance can be continuously tuned between 3 and 40 kΩ with a drain-to-source capacitance of <10 fF. The temperature coefficient of resistance is between -5 and -20 Ω/°C (for V GS less than the pinch-off voltage). The combination of large resistance and low capacitance can result in high receiver sensitivity without sacrificing amplifier dynamic range. The feedback FET was fabricated adjacent to 1.8-μm-gate-length JFETs with transconductances of 110 mS/mm, gate-to-source capacitances of 1.3 pF/mm, and DC amplifier voltage gains of 100. The compatibility of these transistor structures indicates that an integrated preamplifier with dynamically tunable bandwidth can be realized 相似文献
69.
AR Jude DV Greathouse RE Koeppe LL Providence OS Andersen 《Canadian Metallurgical Quarterly》1999,38(3):1030-1039
In the linear gramicidins, the four aromatic residues at positions 9, 11, 13, and 15 are well-known to be important for the structure and function of membrane-spanning gramicidin channels. To investigate whether the "spacer" residues between the tryptophans in gramicidin A (gA) are important for channel structure and function, D-Leu-10, -12. and -14 of gA were replaced by Ala, Val, or Ile. (For practical reasons, the Ile substitutions were introduced into the enantiomeric gramicidin A-, gA-.) Circular dichroism spectra of [D-Ala10,12,14]gA, [D-Val10,12,14]gA, or [Ile10,12,14]gA- incorporated into sodium dodecyl sulfate micelles or 1, 2-dimyristoyl-sn-glycero-3-phosphocholine vesicles differ from the spectrum of the native [D-Leu10,12,14]gA. All the analogue spectra display reduced ellipticity at both 218 and 235 nm, indicating the presence of double-stranded conformers with the Ala analogue spectra showing the largest departure from the native gA spectra. Size-exclusion chromatograms of the Val and Ile analogues show both monomer and dimer peaks, accompanied by peak broadening; the chromatograms for the Ala analogue show broad, overlapping peaks and suggest the presence of higher oligomers and/or (rapidly) interconverting conformations. All three analogues form membrane-spanning channels, with the channel-forming potency of the Ala analogue being much less than that of gA or the other analogues. In 1.0 M CsCl, the conductance of each analogue channel is approximately 25% less than that of [D-Leu10,12,14]gA channels. The lifetimes of the analogue channels also are less than of [D-Leu10,12, 14]gA channels, with the largest (8-fold) reduction being for [D-Ala10,12,14]gA channels. Hybrid channel experiments show that the beta6.3-helical backbone folding pattern is retained in the channel-forming subunits and that the substitutions primarily influence ion entry. Both the bulk and the stereochemistry of the aliphatic residues between the tryptophans of gA are important for channel structure and function. 相似文献
70.
L Ozzello CM De Rosa EW Blank K Cantell RL Ceriani DV Habif 《Canadian Metallurgical Quarterly》1993,25(3):265-276
An immunoconjugate composed of natural interferon alpha (nIFN alpha) bound in a noncleavable fashion to a monoclonal antibody (MoAb) recognizing a breast epithelial membrane mucin (Mc5) was used to to treat xenografts of a human mammary carcinoma cell line (MCF-7) growing in nude mice. The immunoconjugate (nIFN alpha/Mc5) was administered as 20 intralesional (i.l.) injections to 1 of 2 xenografts in each animal. It was found that nIFN alpha/Mc5 produced a significant enhancement of the growth inhibitory actions of nIFN alpha on the injected tumors. Further enhancement was obtained when nIFN gamma or nIFN gamma together with Mc5 (at a dose 10 times larger than that present in nIFN alpha/Mc5) were added to the immunoconjugate. Biodistribution experiments showed that the uptake of 125I-nIFN alpha/Mc5 by the tumors was greater and its elimination slower than for 125I-nIFN alpha alone or conjugated to irrelevant mouse IgG1. In addition, the immunoconjugate up-regulated the antigenic expression of a breast epithelial membrane mucin by the carcinoma cells, an up-regulation which was not significantly different from that produced by nIFN alpha alone. The contralateral noninjected tumors exposed to systemic levels of the immunoconjugate showed an enhancement of antitumor effects, but to a lesser extent than the injected tumors. These findings suggest that the enhancement of the growth inhibitory action of the immunoconjugate was related to the specific binding of Mc5 which targeted the IFN to the carcinoma cells and impeded its elimination. It is likely that the targeting was favored by the IFN-mediated up-regulation of antigenic expression by the carcinoma cells, thereby producing a cascade of interrelated effects. The results of this study point out the feasibility and potential usefulness of IFN treatment by means of immunoconjugates as well as the worth of pursuing and improving this form of therapy. 相似文献