首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   330篇
  免费   5篇
  国内免费   1篇
电工技术   6篇
化学工业   99篇
金属工艺   4篇
机械仪表   4篇
建筑科学   9篇
能源动力   8篇
轻工业   25篇
水利工程   1篇
无线电   22篇
一般工业技术   39篇
冶金工业   103篇
原子能技术   6篇
自动化技术   10篇
  2022年   2篇
  2021年   4篇
  2020年   3篇
  2019年   1篇
  2018年   2篇
  2017年   6篇
  2016年   4篇
  2015年   6篇
  2014年   6篇
  2013年   5篇
  2012年   9篇
  2011年   15篇
  2010年   9篇
  2009年   11篇
  2008年   14篇
  2007年   9篇
  2006年   4篇
  2005年   8篇
  2004年   7篇
  2003年   10篇
  2002年   7篇
  2001年   11篇
  2000年   6篇
  1999年   9篇
  1998年   38篇
  1997年   27篇
  1996年   23篇
  1995年   14篇
  1994年   12篇
  1993年   9篇
  1992年   6篇
  1991年   3篇
  1989年   2篇
  1988年   1篇
  1987年   1篇
  1986年   2篇
  1984年   4篇
  1983年   2篇
  1982年   3篇
  1981年   4篇
  1980年   4篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1975年   3篇
  1974年   1篇
  1972年   2篇
  1971年   1篇
排序方式: 共有336条查询结果,搜索用时 0 毫秒
21.
M Numano  Y Tominaga  K Uchida  A Orihara  Y Tanaka  H Takagi 《Canadian Metallurgical Quarterly》1998,22(10):1098-102; discussion 1103
In secondary hyperparathyroidism (2HPT) fundamentally all parathyroid glands, including supernumerary glands, become hyperplastic, and stimulation of parathyroid glands continues after parathyroidectomy (PTx). Therefore supernumerary glands have special significance during surgery for 2HPT, whether persistent or recurrent HPT. In the present study 570 patients underwent initial total PTx with a forearm autograft. The frequency, type, location, histopathology, and clinical significance of the supernumerary glands were evaluated. At the initial operation 90 supernumerary glands were removed from 82 to 570 patients (14.4%); 12 patients (2.1%) required extirpation of supernumerary glands for persistent/recurrent HPT. Altogether 104 supernumerary glands were identified at operation in 94 of the 570 patients (16.5%). Among these 104 glands, 25 (24.0%) were of the rudimentary, or split, type and 79 (76.0%) of the proper type. Supernumerary glands were most frequently identified in the thymic tongue (53/104, 51.0%); 32 (60.4%) of these 53 glands were identified only microscopically. In 6 of the 570 cases (1.1%), reoperation was required for persistent HPT due to supernumerary glands located in the mediastinum, and 6 patients underwent neck reexploration for recurrence. Histopathologically, 61 of 104 (58.7%) supernumerary glands, including 36 glands recognized only microscopically, showed diffuse hyperplasia, and 43 (41.3%) displayed nodular hyperplasia. Residual small supernumerary glands with diffuse hyperplasia have the potential to be transformed to nodular hyperplasia during long-term hemodialysis. Therefore all parathyroid glands including supernumerary glands should, if possible, be removed at the initial operation. Routine removal of the thymic tongue and careful examination of the regions surrounding the lower poles of the thyroid, especially on the left side, are important steps in the surgical treatment.  相似文献   
22.
Japanese Society of Cryopreserved Thoracic Tissue Implantation was recently set up. Cryopreserved allograft valves are about to pervade in Japan. To clarify the interest, demands and supply of cryopreserved allograft valve in the area of Kyushu and Yamaguchi, we performed questionnaire investigation regarding this issue. Collection rate of this questionnaire was 87.5% (35/40 hospitals). Ninety-seven percent of the hospitals answered that they were interested in cryopreserved allograft. Ninety-four percent of the hospitals answered that they did not ethically hesitate to use cryopreserved allograft. Ninety-one percent of the hospitals hoped to perform cardiac surgery using allograft aortic valve if allograft is available. With respect to securing donors of allograft, two-third of the hospitals did not decide whether they could be involved in obtaining donors of allograft. As the number of the cadaver kidney donors is about 20 per year in the area of Kyushu and Yamaguchi, shortage of donors of allograft valve is anticipated.  相似文献   
23.
24.
Knowledge of the scene illuminant spectral power distribution is useful for many imaging applications, such as color image reproduction and automatic algorithms for image database applications. In many applications accurate spectral characterization of the illuminant is impossible because the input device acquires only three spectral samples. In such applications it is sensible to set a more limited objective of classifying the illuminant as belonging to one of several likely types. We describe a data set of natural images with measured illuminants for testing illuminant classification algorithms. One simple type of algorithm is described and evaluated by using the new data set. The empirical measurements show that illuminant information is more reliable in bright regions than in dark regions. Theoretical predictions of the algorithm's classification performance with respect to scene illuminant blackbody color temperature are tested and confirmed by using the natural-image data set.  相似文献   
25.
26.
The chromosomal location of the human gene for the alpha subunit of interleukin-5 receptor (IL5RA) has been determined. The human IL5RA gene was localized to the short arm of chromosome 3 by Southern blot analysis of DNA from a panel of mouse-human hybrid somatic cell lines. The IL5RA gene has been further localized to human chromosome region 3p24-3p26 by in situ hybridization of a molecularly cloned IL5RA cDNA fragment to metaphase chromosomes. The results suggest that the IL5RA locus is unlinked to other members of the hematopoietic receptor family. Assignment of the IL5RA gene to chromosome 3 at bands p26-p24 raises the possibility that it may be altered by certain nonrandom chromosomal abnormalities arising in human hematopoietic malignancies and solid tumors.  相似文献   
27.
Poly(ethylene carbonate)/poly(lactic acid) blends were successfully prepared by means of a solution film-casting method, and their physicochemical properties were investigated. PEC/PLA blends exhibit partial miscibility and are characterized by the interaction of the ester and carbonic ester groups. One such interaction is between partial charges in –C–O– in –O–C=O of PLA and the carbonyl –C=O of PEC. Another is between –C–O– in –O–C=O of PLA and –C–O– in –CH2–O– of PEC. The value of Tg varies by more than 10 °C across the blends. PEC does not significantly influence the melting temperature of neat PLA, but non-spherical spherulites are formed in PEC-rich blends, whereas the spherulites are spherical with an average size of 30 μm in PLA-rich blends. Crystallization of PLA is influenced by the addition of flexible PEC and by the proportion of PLA in the blends. Interestingly, addition of at least 10 wt% PLA increased Tg, with a crystallinity, Xc of 47% and better thermal degradation properties, with the temperature at 5 wt% weight loss (Td5) more than 30 °C higher than for neat PEC.  相似文献   
28.
This paper deals with a harmonic compensation method using a synchronous machine with resonant field circuits. Harmonics have become one of the major problems in power systems and a lot of methods of harmonic suppression have been studied. The authors have proposed a new method of harmonic suppression using a synchronous machine excited with the 6th harmonic current. This paper shows that armature inductances for the 5th or 7th harmonics decrease when the field circuits are connected to capacitors resonating at the 6th harmonic. The variations of armature impedances are explained theoretically by Park's equations. The optimal capacitances are selected so as to resonate with field inductances for the short-circuited armature. The experiments to suppress the 5th and 7th harmonics using the synchronous machine are successful  相似文献   
29.
This article proposes a method for estimating various parameters of a reflection model from a single color image of an object. We used an RGB charge-coupled device (CCD) camera for imaging and parameter estimation. We assumed the object surface is composed of an inhomogeneous dielectric material and used the Phong model to describe the surface's dichromatic reflection. This approach also generalizes to objects with smooth convex surfaces  相似文献   
30.
The relationship between the activities of endogenous enzymes in milled rice and accumulation of chemical components in the rice grains during cooking was investigated. Maltose and soluble starch were optimally hydrolyzed around 60 °C by both crude extracts and purified α-glucosidases of milled rice. Gelatinization onset temperature of rice flour was determined to be 63 °C with DSC analysis under usual cooking condition. Hydrolytic activities on carbohydrates and proteolytic activities of milled rice were enhanced at pH 5 compared to pH 7 at the range of 4–80 °C. When rice was cooked at pH 5, glucose and amino acids highly accumulated with soaking for 16 h before heating. We propose a new method of cooking with prolonged soaking at acidic pH, which is effective for increasing the amounts of chemical components in cooked rice.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号