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51.
PURPOSE: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. METHODS: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD +/- SD) and repeatability coefficient (2 x SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. RESULTS: MD +/- SD for repeated measurements at rest and during flow augmentation were 0 +/- 2 mmHg and 1 +/- 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 +/- 7 mmHg at rest and 17 +/- 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. CONCLUSION: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty.  相似文献   
52.
Mechanically alloyed TiMo alloy particles were evaluated by high-resolution electron microscope observations. The particles were mechanically alloyed for 36, 72, 144 and 288 ks. Specimens for transmission electron microscopy were prepeared by electroplating the particles together with nickel on copper sheets and using an ion-milling machine. It was not difficult to distinguish MA particles in the specimens. MA particles consisted of small island crystalline parts, 20–50 nm diameter, and amorphous parts. Lattice fringes of island crystalline parts were measured and the materials produced by mechanical alloying were identified by their lattice spacings. After alloying for 36 ks, pure titanium and molybdenum still remained and a small amount of -TiMo alloy was confirmed. After alloying for 72 ks, almost all crystalline parts were -TiMo alloy. -TiMo and TiFe were found after alloying for 144 ks. -TiMo alloy seems to be transformed from -TiMo alloy on alloying for 144 and 288 ks.  相似文献   
53.
The current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Specifications impose fairly strict limits on the use of its live-load distribution factor for design of highway bridges. These limits include requirements for a prismatic cross section, a large span-length-to-width ratio, and a small plan curvature. Refined analyses using 3D models are required for bridges outside of these limits. These limits place severe restrictions on the routine design of bridges in California, as box-girder bridges outside of these limits are frequently constructed. This paper presents the results of a study investigating the live-load distribution characteristics of box-girder bridges and the limits imposed by the LRFD specifications. Distribution factors determined from a set of bridges with parameters outside of the LRFD limits are compared with the distribution factors suggested by the LRFD specifications. For the range of parameters investigated, results indicated that the current LRFD distribution factor formulas generally provide a conservative estimate of the design bending moment and shear force.  相似文献   
54.
Sato M  Hida N  Ozawa T  Umezawa Y 《Analytical chemistry》2000,72(24):5918-5924
We describe herein fluorescent indicators for cyclic GMP (cGMP) in single living cells. cGMP-dependent protein kinase Ialpha (PKG Ialpha), a receptor for cGMP, was fused with blue- and red-shifted green fluorescent proteins (GFPs) to its N- and C-termini, respectively. Using PKG lalpha delta1-47, in which the dimerization domain was deleted, fluorescence resonance energy transfer between the GFPs was found to increase upon cGMP-induced conformational change in PKG Ialpha delta1-47. We demonstrated that thus-developed fluorescent indicators reversibly responded to cGMP that was produced in nitric oxide-stimulated HEK293 cells. The present genetically encoded fluorescent indicators open a way not only for understanding the dynamics of cGMP signaling in single cells and organisms but also for discovering pharmaceuticals such as isoform-specific inhibitors for phosphodiesterases.  相似文献   
55.
PURPOSE: To investigate the telomere hypothesis of cellular aging as the mechanism for cell cycle arrest in normal human corneal endothelium. METHODS: The corneal endothelium and epithelium from 21 human corneas from 13 donors 5 weeks to 84 years of age were dissected and frozen at -70 degrees C. Purified DNA, digested with the restriction enzyme, HinfI, was run on 0.7% agarose gels, probed with radiolabeled (AATCCC)4, and exposed to a phosphor screen. The length of the terminal restriction fragment (TRF) was determined by densitometry. RESULTS: The cells of the corneal endothelium had TRF lengths ranging from 11.0 to 14.0 kbp (mean, 12.2 +/- 0.9). Corneal epithelial specimens showed TRF lengths that were always less than (mean, 10.4 +/- 1.0; range 9.0-12.0) the corresponding endothelial TRF lengths. Human corneal endothelial cells, transformed with human papillomavirus type 16 oncogenes E6 and E7, showed decreasing TRF lengths from 11 kbp at population doubling level (PDL) 15 to 9.5 kbp at PDL 73. Neither the endothelial and epithelial cells from human donors nor the transformed pre-immortalized human endothelial cells showed evidence of telomerase activity. CONCLUSIONS: Human corneal endothelial cells have long telomeres throughout life. Their limited replicative ability does not appear to result from critically short telomere lengths.  相似文献   
56.
Reduction of singlemode fibre coupling loss in 1.5% Δ planar lightwave circuits from 1.8 to 0.2 dB/point is achieved using simple vertically and laterally tapered spot-size converters. These spot-size converters were used to realise an arrayed-waveguide grating with a very low insertion loss of 0.7 dB  相似文献   
57.
We measured electromyograms (EMGs) of genioglossus muscle (GG) and inspiratory intercostal muscle (IIM) in both rapid eye movement (REM) sleep and non-REM sleep of 12 patients with obstructive sleep apnea (OSA) to examine the influence of different sleep stages on upper airway muscle activity during sleep apnea. Quantifications of both muscle activities were assessed by their individual peak amplitude of integrated inspiratory EMG. Genioglossus and IIM activities showed a qualitatively similar cyclic change with an alteration of apneic and ventilatory phases during both non-REM and REM sleep. Both muscle activities increased gradually in the late apneic phase and reached each peak at the opening of the upper airway and, subsequently, decreased gradually. There were no significant differences in both muscles activities in either the ventilatory or early apneic phase between non-REM sleep and REM sleep. On the other hand, GG and IIM activities in the late apneic phase during REM sleep were significantly lower than those during non-REM sleep. The relative activity of GG to IIM in the late apneic phase was significantly lower during REM sleep than that during non-REM sleep. These results indicate that upper airway and intercostal muscle activation in the later apneic phase during REM sleep were inhibited compared with those during non-REM sleep and that this inhibition was observed predominantly in upper airway muscles.  相似文献   
58.
We designed optical Y-branch waveguides with a stabilized splitting ratio by using a new design approach based on the wavefront matching method. The designed Y-branches were fabricated using silica-based planar lightwave circuit technology. We suppressed any variation in the splitting ratio of the Y-branch experimentally and obtained excess losses of <0.35 dB over a wide wavelength range of 1.3-1.7 /spl mu/m.  相似文献   
59.
A system integrated LSI chip (SLSI) that contains eleven 4-Mb DRAMs, six 64-kb SRAMs, and an 18 K-gate array, for a graphics application system is described. To implement the SLSI on a silicon chip, three key techniques have been developed: (1) system redundancy for defect relief; (2) chip configuration and fabrication with blade masking to achieve a hybrid 38.16×50.4-mm2 chip; and (3) large-capability and high-reliability 324-pin 54×86-mm2 plastic pin grid array package. Using a system redundancy technique, a 60% yield for the SLSI is achieved with a 40% yield for the DRAM itself. That is twice the 30% yield of the conventional repair scheme. Access times are 65 ns for the DRAM and 14 ns for the SRAM with a 3.9-W chip power dissipation  相似文献   
60.
Hida  Y. Inoue  Y. Kominato  T. 《Electronics letters》2004,40(18):1118-1119
It is shown that the polarisation dependent wavelength shift (PD-/spl lambda/) of a silica-based arrayed waveguide grating (AWG) is proportional to its output port location as a result of the birefringence in a slab waveguide. This PD-/spl lambda/ was eliminated to less than 0.01 nm by inserting a half waveplate across the slab waveguide.  相似文献   
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