全文获取类型
收费全文 | 986篇 |
免费 | 24篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 1011篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 25篇 |
2020年 | 6篇 |
2019年 | 13篇 |
2018年 | 26篇 |
2017年 | 16篇 |
2016年 | 19篇 |
2015年 | 12篇 |
2014年 | 29篇 |
2013年 | 74篇 |
2012年 | 39篇 |
2011年 | 52篇 |
2010年 | 46篇 |
2009年 | 43篇 |
2008年 | 52篇 |
2007年 | 49篇 |
2006年 | 24篇 |
2005年 | 37篇 |
2004年 | 23篇 |
2003年 | 34篇 |
2002年 | 29篇 |
2001年 | 13篇 |
2000年 | 20篇 |
1999年 | 23篇 |
1998年 | 49篇 |
1997年 | 32篇 |
1996年 | 20篇 |
1995年 | 22篇 |
1994年 | 27篇 |
1993年 | 20篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有1011条查询结果,搜索用时 31 毫秒
101.
T Nakamura K Sato N Harada M Sakuramoto R Miyahara T Maekawa S Fukuda 《Canadian Metallurgical Quarterly》1997,35(7):776-783
A 12-year-old boy was admitted to our hospital because of abnormal shadows on a chest radiograph, slight fever, and superficial lymphadenopathy. Laboratory examination showed anemia (Hb 9.9 g/dl) and hyperimmunoglobulinemia (IgG 5469 mg/dl) without M protein. A chest CT scan showed bilateral diffuse shadows and bilateral hilar lymphadenopathy. Biopsy specimens of an inguinal lymph node and a lung showed many lymphoid follicles with germinal centers, and marked infiltration of mature plasma cells in the interfollicular area without destruction of follicular structures. The polyclonality of the plasma cells was confirmed by immunohistochemistry. The patient was not treated because these results excluded malignant disease and he was asymptomatic. At the age of 17 years, he was admitted to our hospital again because of dyspnea and a tendency to bleed. Interstitial pneumonia, hyperimmunoglobulinemia (IgG 13900 mg/dl), and anemia (Hb 6.6 g/dl) were found, along with thrombocytopenia (2.5 x 10(4)/mm3) and proteinuria. The serum interleukin-6 level was high: 177 pg/ml. Bronchoalveolar lavage fluid contained many plasma cells. Therapy with corticosteroids and immunosuppressant medication was effective. Our diagnosis was plasma cell interstitial pneumonia as a manifestation of multicentric Castleman's disease. 相似文献
102.
Masahiro Kozako Shinya Ohtsuka Takashi Matsuhisa Masayuki Hikita 《Electrical Engineering in Japan》2003,145(3):25-32
We investigated the propagation properties of Lamb waves in a GIS tank, using time–frequency analysis to diagnose the insulation performance of GIS. We measured the acoustic signals excited by metallic particles colliding with the tank sheath, and those emitted by partial discharge in the GIS. The wavelet transform was used to decompose the wave data into its time–frequency components. As a result, it was confirmed that Lamb waves with the dispersive property of the velocity are excited and propagate in a spiral path along the tank wall due to the cylindrical structure of the tank. Taking these results into consideration, we propose a new technique for identification of defect locations in GIS based on time–frequency analysis of acoustic signals with the wavelet transform. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(3): 25–32, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10163 相似文献
103.
The expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats ingested with saline was investigated. The alteration in regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open reading frame). Rats were freely given saline as drinking water for 7 days. Regucalcin mRNA levels in the kidney cortex were suppressed by saline ingestion. When calcium chloride (10 mg Ca/100 g body weight) was intraperitoneally administered to rats ingested with saline for 7 days, the effect of calcium administration to increase regucalcin mRNA levels was weakened by saline ingestion. Such effect was also seen by the administration of 2.5 and 5 mg Ca/100 g. Regucalcin mRNA levels in the kidney cortex of spontaneous hypertensive rats (SHR) were not appreciably increased by the administration of calcium (10 mg/100 g). Meanwhile, calcium content in the kidney cortex was significantly elevated by the administration of calcium (10 mg/100 g) to normal rats. This increase was weakened in saline-ingested rats. Moreover, Ca2+/calmodulin-dependent protein kinase activity in the cytosol of kidney cortex was significantly decreased by saline ingestion. These results suggest the possibility that saline ingestion-induced suppression of regucalcin mRNA expression in the kidney cortex is partly involved in the attenuation of Ca2+ signalling. 相似文献
104.
Nowadays our society demands the reuse of industrial products. Then we should not only re-investigate the materials of products but also originate a new design method of industrial products. We have investigated the cellular structure by using abandoned paper, because the cell's shape can be proposed arbitrarily by folding a paper. As examples, we have proposed the structure constructed by connecting many folded cells formed in a hexagonal cross area. This structure will have characteristics such as almost high rigidity, high stiffness, crushing stress, relative insensitivity to the overall loss of stability. To estimate the characteristics of these structures, we must analyze the deformation in loading. When the structure with thin walls formed by paper is loaded, the shape of deformation is different from that of the metal, wall swells and does not maintain its flatness. Therefore, we cannot apply the traditional theory of elasticity for the analysis. In this paper, we propose a new estimation method by analyzing the swelling. 相似文献
105.
For asphaltene obtained from vacuum residues of three different kinds of crude oils (Khafji, Maya, and Iranian-Light), the energy-minimum conformation calculated by molecular mechanics-dynamics simulations showed that aggregated structures of asphaltene molecules through noncovalent interactions are the most stable conformation. Changes of aggregated structures by heating or solvent treatment were investigated by using the molecular dynamics calculation. For Khafji and Iranian-Light asphaltenes, the simulation showed that the aggregated structure was dissociated at 673K, while for Maya asphaltene the dissociation behavior was not observed, showing that Maya asphaltene seems difficult to be dissociated by heating, compared to other asphaltenes. In contrast, the simulation of relaxation of the Maya aggregates in quinoline showed that at 573K a part of aggregates was dissociated more easily than Khafji and Iranian-Light asphaltenes. These results above suggest that the effects of heating and solvent treatment on the structural relaxation of asphaltene aggregates can be different. 相似文献
106.
Hokkaido coals were subjected to benzene extraction and non-catalytic hydrotreatment, alternatively, under progressive increase of temperature from 200 to 400 °C. For Taiheiyo coal the aliphatic materials in the hydrogen-rich part of the coal were converted to benzene soluble products at lower temperatures. With the increasing reaction temperature, aromaticity of the benzene solubles increased gradually. On the other hand, for Ohyubari coal, the structure of the benzene solubles were essentially the same for products obtained under all temperatures. Also, in the case of Taiheiyo coal (C : 76.9 %) the plastic state was not observed up to 400 °C, but for Ohyubari coal (C : 85.6 %) the onset of the plastic state was evident. It was assumed that there was an intimate relationship between the occurrence of plastic state and the structural uniformity of coal. 相似文献
107.
108.
H Nakano Y Ohnishi J Maekawa Y Ishii T Nakamura K Matsuzawa N Narita 《Canadian Metallurgical Quarterly》1996,34(7):765-770
In sleep-disordered breathing, tracheal sounds disappear during apnea and vary cyclicly during hypopnea. We tried to detect these changes in tracheal sounds automatically with a personal computer, and we evaluated the diagnostic accuracy of this system for detecting sleep-disordered breathing. Polysomnography and tracheal sound recording were done in 33 subjects with possible sleep apnea/hypopnea syndrome. Eighteen had positive results defined as an apnea/hypopnea index greater than 15. Tracheal sounds were digitized and a personal computer was used to calculate short time power spectra (44-600 Hz) every 0.2 seconds by the fast Fourier transform. The moving averages (18 seconds) of the logarithms of the power spectra were calculated every 2 seconds. Transient falls in the moving averages of more than 12 dB were detected. Those that were lower than 5 dB above the level of background noise were classified as tracheal sound apneas. The number of falls of more than 12 dB and the number of tracheal sound apneas correlated strongly with the number of apneas plus hypopneas (r = 0.95) and with the number of apneas (r = 0.97), respectively. The sensitivity and specificity of tracheal sound analysis for the sleep apnea/hypopnea syndrome (as defined above) were 89% and 60%, respectively, when the criteria was more than 15 falls of more than 12 dB per hour. We conclude that tracheal sound analysis by this method is useful as a screening test for the sleep apnea/hypopnea syndrome. 相似文献
109.
BACKGROUND: Oral clonidine may influence plasma glucose and lipid homeostasis by modulating endocrinologic responses to surgical stress. The effect of oral clonidine premedication on plasma glucose and lipid homeostasis associated with exogenous glucose infusion were investigated in children undergoing minor surgery. METHODS: Otherwise healthy children (n, 120; aged 3-13 yr) were assigned randomly to six groups according to the glucose concentration of the intravenous solution (0%, 2%, or 5%, at a rate of 6 ml kg(-1) x h(-1)) and the preoperative medications (4 microg/kg clonidine or placebo given 100 min before anesthesia) they were to receive. The plasma concentrations of glucose, nonesterified fatty acid, ketone bodies, epinephrine, norepinephrine, and cortisol were determined. RESULTS: Infusion of 5% glucose caused hyperglycemia (mean glucose concentration >200 mg/dl) in six children receiving placebo and two receiving clonidine. Although the mean plasma glucose concentration increased in three placebo groups, it was unchanged and the plasma concentrations of total ketone bodies and nonesterified fatty acid were increased in children receiving clonidine and glucose-free solution. The plasma epinephrine, norepinephrine, and cortisol levels in children receiving placebo increased in response to surgery. Clonidine attenuated the increase in catecholamines and cortisol. CONCLUSIONS: Oral clonidine premedication attenuated the hyperglycemic response, probably by inhibiting the surgical stress-induced release of catecholamines and cortisol. Infusion of 2% of glucose maintained plasma glucose concentrations within physiologic ranges in children receiving clonidine. 相似文献
110.
The JSNS, a spallation neutron source of J-PARC (JAERI-KEK Joint Project of the High Intensity Proton Accelerator) has 23 neutron beam lines. In the present study, a database was formulated for an optimum shielding design using the MCNP-X code. The calculations involved two steps. In the first step, the neutron distributions were created in the typical neutron beam line with a model that included the spallation neutron source target. The neutron currents evaluated flowed from the duct into the duct wall which was the boundary source for the bulk shield surrounding the beam line. In the second step, bulk-shield calculations were performed for the various shielding materials (iron, concrete, heavy concrete and so on) used and their composites up to thicknesses of 3 m. The results were compared with each other. Composite material shields of iron and such hydrogeneous materials as polyethylene or concrete were more effective. A typical design was prepared for a beam line within 25 m distance from a moderator, as a sample. 相似文献