全文获取类型
收费全文 | 4473篇 |
免费 | 61篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 47篇 |
综合类 | 1篇 |
化学工业 | 388篇 |
金属工艺 | 69篇 |
机械仪表 | 57篇 |
建筑科学 | 125篇 |
矿业工程 | 15篇 |
能源动力 | 42篇 |
轻工业 | 294篇 |
水利工程 | 29篇 |
石油天然气 | 7篇 |
无线电 | 294篇 |
一般工业技术 | 451篇 |
冶金工业 | 2298篇 |
原子能技术 | 19篇 |
自动化技术 | 402篇 |
出版年
2021年 | 29篇 |
2019年 | 20篇 |
2018年 | 25篇 |
2017年 | 32篇 |
2016年 | 17篇 |
2015年 | 32篇 |
2014年 | 59篇 |
2013年 | 150篇 |
2012年 | 103篇 |
2011年 | 105篇 |
2010年 | 57篇 |
2009年 | 61篇 |
2008年 | 89篇 |
2007年 | 106篇 |
2006年 | 103篇 |
2005年 | 74篇 |
2004年 | 79篇 |
2003年 | 84篇 |
2002年 | 74篇 |
2001年 | 57篇 |
2000年 | 54篇 |
1999年 | 116篇 |
1998年 | 701篇 |
1997年 | 403篇 |
1996年 | 259篇 |
1995年 | 162篇 |
1994年 | 142篇 |
1993年 | 147篇 |
1992年 | 61篇 |
1991年 | 64篇 |
1990年 | 56篇 |
1989年 | 63篇 |
1988年 | 61篇 |
1987年 | 48篇 |
1986年 | 48篇 |
1985年 | 64篇 |
1984年 | 28篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 46篇 |
1980年 | 42篇 |
1979年 | 27篇 |
1978年 | 31篇 |
1977年 | 80篇 |
1976年 | 140篇 |
1975年 | 31篇 |
1974年 | 23篇 |
1973年 | 29篇 |
1972年 | 19篇 |
1971年 | 18篇 |
排序方式: 共有4538条查询结果,搜索用时 31 毫秒
981.
PH Wiernik DF Moore JM Bennett SE Vogl JE Harris S Luger MM Oken JH Glick 《Canadian Metallurgical Quarterly》1998,30(5-6):601-607
Mitoguazone, an investigational agent with significant activity in advanced lymphoma, was added to a modified CHOP regimen (COPA) in an effort to improve the activity of standard therapy in 66 previously untreated patients with stages II-IV lymphoma and diffuse histology of intermediate or high grade other than lymphoblastic in this phase II pilot study. The regimen was well tolerated and the complete response rate in diffuse large cell lymphoma was 55%. Sixty-five percent of all complete responders were in complete response for at least one year. Despite these excellent results. it is unlikely that the addition of mitoguazone improved results compared with those obtained with standard therapy alone, since similar results have been frequently reported with the latter. 相似文献
982.
D. A. Petti B. J. Merrill S. T. Polkinghorne L. C. Cadwallader R.L. Moore 《Journal of Fusion Energy》1997,16(1-2):125-131
A number of postulated in-vessel loss of coolant accidents (LOCAs) associated with the first wall and baffle cooling systems of the ITER detailed design have been analyzed for the ITER Non-site Specific Safety Report (NSSR-1). A range of break sizes from one first wall tube break (1.57 × 10–4 m2) to damage to all in-vessel components (0.6 m2 break) have been examined. These events span the ITER event classification from likely events to extremely unlikely events. In addition, in-vessel pipe breaks in combination with bypass of the two confinement barriers through a generic penetration have been examined. In all cases, when the vacuum vessel pressure suppression system is activated, most of the radioactive inventory is carried to the suppression pool where it remains for the duration of the event. Releases in these events are well within ITER release limits. 相似文献
983.
White V. Heinicke P. Berman E. Constanta-Fanourakis P. MacKinnon B. Moore C. Nicinski T. Petravick D. Pordes R. Quigg L. 《IEEE transactions on nuclear science》1987,34(4):763-767
The VAXONLINE software system, started in late 1984, is now in use at 12 experiments at Fermilab, with at least one VAX or MicroVax. Data acquisition features now provide for the collection and combination of data from one or more sources, via a list-driven Event Builder program. Supported sources include CAMAC, FASTBUS, Front-end PDP-11's, Disk, Tape, DECnet and other processors running VAXONLINE. This paper describes the functionality provided by the VAXONLINE system, gives performance figures and discusses the ongoing program of enhancements. 相似文献
984.
VTM--an image-processing system for measuring ocular torsion 总被引:3,自引:0,他引:3
This paper reports a new, fast, accurate realization of an image-processing method of measuring ocular torsion (rotation of the eyeball around the visual axis) called Video Torsion Measurement (VTM). The method is to cross-correlate the two grey-level distributions of an arc of the iris from two separate images using a fast image processor card interfaced to an IBM-AT compatible computer. The card (Matrox MVP-AT) is supplied with a library of low-level functions for controlling the hardware operations of the board and the VTM system software, which is written in the C programming language, incorporates these low-level functions to interface with the MVP-AT board as well as carrying out the data-acquisition and processing algorithms. These programs: acquire an image of an iris illuminated by a single infrared (IR) light source; threshold this image in order to identify the pupil; calculate the pupil area and locate the centre of the pupil using a centre-of-gravity algorithm; record the grey-level distribution along an arc 256 pixels long at a selected radius from the pupil centre; carry out an FFT on this (interpolated) grey level distribution; store the parameters of this reference FFT and cross-correlate the comparable iral grey-level distribution from other test images of the same eye in order to determine the amount of torsional rotation of the test images relative to the reference image. This system is interactive and is designed for operation in a clinical testing situation with a minimum of operator intervention. The VTM system has a resolution of the order of 0.1 deg depending on the arc radius used and it has been validated in two ways: by using it to measure known torsional rotations of an artificial iris-like pattern and also by direct simultaneous comparison of measures on the same human iris images from VTM and those from the standard 35 mm photographic procedure of measuring torsion. 相似文献
985.
KS Reynolds MH Song WD Heizer CB Burns DA Sica KL Brouwer 《Canadian Metallurgical Quarterly》1998,15(8):1281-1285
PURPOSE: Ranitidine plasma concentration vs. time profiles and the extent of ranitidine absorption were examined in the presence and absence of pancreatico-biliary secretions in order to elucidate factors which may contribute to secondary peaks after oral ranitidine administration. METHODS: Ranitidine solution (300 mg) was administered to 4 fasting healthy subjects via an indwelling small-bore oroenteric tube located approximately 16 cm distal to the pylorus On 3 consecutive days, subjects randomly received ranitidine alone (control), ranitidine 10 min after 0.04 micrograms/kg IV cholecystokinin (CCK) sufficient to cause gall bladder emptying into the duodenum, and ranitidine 30 min after inflation of an occlusive duodenal balloon located approximately 10 cm distal to the pylorus to prevent pancreatico-biliary secretions from reaching the dosing port or beyond. Small bowel transit time (SBTT; min) was measured by breath H2. Serial blood samples, obtained over 12 hours in each treatment, were analyzed by HPLC to determine ranitidine AUC0-12 (ng*h/mL), as well as Cmax (ng/mL) and Tmax (min) of the first and subsequent peaks, if subsequent peaks were observed. RESULTS: Ranitidine AUC0-12 and Cmax were not altered significantly by treatments; treatment effects on SBTT varied. Secondary peaks were observed in subjects #1 and #3 during the control treatment and subjects #2 and #4 during the CCk treatment. No secondary peaks were observed in any subject during the balloon treatment, and Tmax1 was delayed. CONCLUSIONS: Results support the hypothesis that pancreatico-biliary secretions (present in the intestinal lumen during control or CCK treatment) and gastrointestinal transit time may influence the occurrence of secondary peaks in ranitidine concentration vs. time profiles. 相似文献
986.
CB Menice J Hulvershorn LP Adam CA Wang KG Morgan 《Canadian Metallurgical Quarterly》1997,272(40):25157-25161
Contraction of smooth muscle cells is generally assumed to require Ca2+/calmodulin-dependent phosphorylation of the 20-kDa myosin light chains. However, we report here that in the absence of extracellular calcium, phenylephrine induces a contraction of freshly isolated ferret aorta cells in the absence of increases in intracellular ionized calcium or light chain phosphorylation levels but in the presence of activation of mitogen-activated protein kinase. A protein at 36 kDa co-immunoprecipitated with the mitogen-activated protein kinase and was identified as the actin-binding protein, calponin, by immunoblot. An overlay assay further confirmed an interaction between the kinase and calponin, even though the kinase did not phosphorylate calponin in vitro. Calponin also co-immunoprecipitated from smooth muscle cells with protein kinase C-epsilon. High resolution digital confocal studies indicated that calponin redistributes to the cell membrane during phenylephrine stimulation at a time when mitogen-activated protein kinase and protein kinase C-epsilon are targeted to the plasmalemma. These results suggest a role for calponin as a signaling molecule, possibly an adapter protein, linking the targeting of mitogen-activated protein kinase and protein kinase C-epsilon to the surface membrane. 相似文献
987.
988.
Compared mean IQ test performance and response styles to cognitive demands of the Wechsler Intelligence Scale for Children (WISC) among 23 Black children (aged 7–10 yrs) who had been adopted by middle-class White families (i.e., transracially adopted) and 23 age-matched Black children who had been adopted by middle-class Black families (i.e., traditionally adopted). Findings indicate that while the traditionally adopted Ss received normal IQ scores, transracially adopted Ss showed nearly 1 standard deviation Full-Scale Scoring advantage over them. A multiple analysis of variance (MANOVA) indicated significant differences in the styles of responding to test demands demonstrated by the 2 groups of Ss, which were conceptualized as contributors to the difference in average test score observed between them. Multivariate analysis of the helping behaviors adopted mothers exhibited when helping their children solve a difficult cognitive task revealed significant differences between Black and White mothers, which were conceptualized as culturally determined. White adopted mothers tended to release tension by joking, grinning, and laughing, while Black adoptive mothers more often released tension in less positive ways such as scowling, coughing, and frowning. White adoptive mothers were more likely than Black adoptive mothers to provide positive evaluations of their children's problem solving efforts. It is concluded that the ethnicity of the rearing environment exerts a significant influence on children's styles of responding to standardized intelligence tests and on their test achievement. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
989.
Influence of potential on the friction and wear of mild steel in a model aqueous lubricant 总被引:1,自引:0,他引:1
N. P. Brandon N. Bonanos P. O. Fogarty M. N. Mahmood A. J. Moore R. J. K. Wood 《Journal of Applied Electrochemistry》1993,23(5):456-462
An electrochemical cell has been designed, based on a Cameron-Plint friction machine, which enables measurement of friction and wear under conditions of controlled potential. For mild steel in a pH 9 aqueous solution of sodium octanoate, varying the potential of the steel over the range –1 to + 1 V vs SHE produced three distinct friction-wear regimes: high friction/low wear, low friction/high wear, and low friction/low wear. These regimes were ascribed to potential dependent changes in the coverage and stability of a lubricating octanoate film on the surface of the steel. Increasing the contact stress amplified the effect of potential on wear, and confirmed that the surface film retained its lubricity at contact stresses capable of causing plastic deformation of the steel. 相似文献
990.
Theory and application of radiation boundary operators 总被引:7,自引:0,他引:7
Moore T.G. Blaschak J.G. Taflove A. Kriegsmann G.A. 《Antennas and Propagation, IEEE Transactions on》1988,36(12):1797-1812
A succinct unified review is provided of the theory of radiation boundary operators. With the recent introduction of the on-surface radiation condition (OSRC) method and the continued growth of finite-difference and finite-element techniques for modeling electromagnetic wave scattering problems, the understanding and use of radiation boundary operators has become increasingly important. Results are presented to illustrate the application of radiation boundary operators in both these areas. Recent OSRC results include analysis of the scattering behavior of both electrically small and large cylinders, a reactively loaded acoustic sphere, and a simple reentrant duct. Radiation boundary operator results include the demonstration of the effectiveness of higher-order operators in truncating finite-difference time-domain grids 相似文献