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   173篇
  免费   6篇
电工技术   2篇
化学工业   35篇
金属工艺   3篇
机械仪表   6篇
能源动力   3篇
轻工业   7篇
水利工程   1篇
无线电   16篇
一般工业技术   31篇
冶金工业   38篇
原子能技术   4篇
自动化技术   33篇
  2024年   1篇
  2023年   1篇
  2022年   4篇
  2021年   4篇
  2020年   4篇
  2019年   3篇
  2018年   6篇
  2017年   1篇
  2016年   2篇
  2015年   1篇
  2014年   5篇
  2013年   11篇
  2012年   12篇
  2011年   4篇
  2010年   7篇
  2009年   2篇
  2008年   7篇
  2007年   8篇
  2006年   7篇
  2005年   4篇
  2004年   3篇
  2003年   5篇
  2002年   1篇
  2001年   4篇
  2000年   2篇
  1999年   6篇
  1998年   7篇
  1997年   7篇
  1996年   11篇
  1995年   10篇
  1994年   5篇
  1993年   1篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1989年   2篇
  1985年   2篇
  1984年   2篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
排序方式: 共有179条查询结果,搜索用时 15 毫秒
31.
We developed a lost alpha detection system to use in burning plasma experiments. The scintillators of Ag:ZnS and polycrystalline Ce:YAG were designed for a high-temperature environment, and the optical transmission line was designed to transmit from the scintillator to the port plug. The required optical components of lenses and mirrors were irradiated using the fission reactor with the initial result that there was no clear change after the irradiation with a neutron flux of 9.6×10(17)?nm(-2) s(-1) for 48 h. We propose a diagnostic of alpha particle loss, so-called alpha particle induced gamma ray spectroscopy. The initial laboratory test has been carried out by the use of the Ce doped Lu(2)SiO(5) scintillator detector and an Am-Be source to detect the 4.44 MeV high energy gamma ray due to the (9)Be(α,nγ)(12)C reaction.  相似文献   
32.
The heavy ion beam probe system in the Large Helical Device (LHD) was improved as follows. At first, the additional new sweeper was installed into the diagnostic port to extend the observable region. By using this sweeper, the potential profile was measured in a wider minor radius range than in previous experiments, in the case of outward shifted magnetic configuration of LHD. Next, the real time control system was installed to control the probe beam orbit for measuring the potential in plasma with large plasma current. In this system, a digital signal processor was used to control the probe beam in real time. The system worked well in the fixed position observation mode. In the sweeping mode for profile measurement, this control system became unstable. The details of this system and the experimental results are reported in this article.  相似文献   
33.
A 16-/64-/256-quadrature amplitude modulation (QAM) demodulator LSI with an all-digital carrier-recovery loop including a novel phase detector and a fractionally/symbol-spaced equalizer is described. The phase detector, which decides the transmitted symbol from received signal power, detects phase errors up to ±45° and enables the loop to internally eliminate the ±80 kHz carrier-frequency offset. The fractionally spaced equalizer is implemented at the same clock rate as the symbol-spaced equalizer by increasing only multiplexers and flip-flops, though the former theoretically requires an operation twice as fast as the latter. A large scale integrator (LSI) operating at a symbol rate up to 8 MBaud is successfully implemented. The 0.5-μm CMOS three-metal technology is used to implement 880 000 transistors in a die size of 12.87×12.39 mm2  相似文献   
34.
Tumours consisting of a mixture of mature adipose and smooth muscle tissues, including those designated lipoleiomyomas, fibrolipoleiomyomas and myolipomas, are exceedingly rare, but most often occur in the uterine corpus. We describe here a case of such a tumour arising in the right round ligament of a 44-year-old woman. The tumour, which measured approximately 20x15x10 cm, was well encapsulated and did not involve the intrapelvic organs. Intricate mixtures of adult adipose tissue and bland smooth muscle exhibited no cellular atypia or nuclear mitotic figures, and there was little vascular proliferation. We diagnosed the lesion as a myolipoma of soft tissue with dual differentiation, and have found only 13 cases of this tumour including our own in the English literature. The present tumour is the first reported in the round ligament. Although this tumour is rare, its recognition is important for the avoidance of erroneous diagnoses.  相似文献   
35.
Monofunctional aldehydes such as acetaldehyde,n-propylaldehyde,n-butylaldehyde,n-hexylaldehyde,n-heptylaldehyde and benzaldehyde affected the reaction between primary amines and malonaldehyde. While the reaction of primary amines and malonaldehyde at pH 7 produced fluorescent 4-methyl-1,4-dihydropyridine-3,5-dicarbaldehydesIa-f, the reaction of the primary amines, malonaldehyde and the aldehydes listed above gave fluorescent 4-substituted 1,4-dihydropyridine-3,5-dicarbaldehydesIIa-j. The primary amines used for this reaction included alkylamines, amino acids and alkanolamines. The optimal ratio of the amine, malonaldehyde and the aldehyde was 1:2:1–2, at which compoundsII were produced quantitatively. Peroxidized lipids which may contain malonaldehyde and other aldehydes could react with the primary amines to produce highly fluorescentII. Fluorescence spectra ofII showed excitation maxima at 386–403 nm and emission maxima at 444–465 nm in phosphate similar to those ofI. The spectra of these 1,4-dihydropyridinesI andII were roughly similar to those of lipofuscin pigment, but they exhibited different characteristics in acid and alkaline media from those of lipofuscin pigment. CompoundsII may be useful as model compounds to elucidate the chemical structure of lipofuscin pigment.  相似文献   
36.
We have established a practical method of complete high-resolution typing for all HLA-A alleles using the polymerase chain reaction (PCR)-restriction fragment-length polymorphism (RFLP) technique combined with allele group- and sequence-specific amplification. The second and third exons of the HLA-A gene, in which most allelic variations are observed, were separately amplified by PCRs with 3 and 4 group-specific primer pairs, respectively. Each PCR-amplified product was digested by allele-specific restriction endonucleases and then subjected to electrophoresis on a 10% polyacrylamide gel. In this way, 62 out of 79 HLA-A alleles could be discriminated by the RFLP patterns derived from the genetic polymorphism in the exon 2 and 3 domains. The remaining 17 alleles could be defined unequivocally by either PCR-RFLP analysis after exon 4 amplification or PCR analysis with sequence-specific primers (SSP). By this method, complete HELA-A genotyping for all homozygous and heterozygous combinations can be accomplished, establishing technically simple, economical and practical routine typing of the HLA-A gene, especially for small samples.  相似文献   
37.
In La2–xBaxCuO4 (LBCO) and La1.8–xNd0.2BaxCuO4 (LNBCO), the low-temperature structural change at T1 (=60–110K), resulting from tilt of the CuO6 octahedra, is easily suppressed at high pressures. However, the structural change of LNBCO (x=0.125) remains up to 2GPa though it jumps from T1(110K) to T* (60K), where the electric resistivity begins to upturn, at 0-1.5GPa. The upturn of is also suppressed at high pressures, and the superconducting critical temperature Tc is fully restored except in a very narrow x-range around x=0.125. The Tc for x 0.125 is appreciably lower at 2GPa than those for other Ba-contents.  相似文献   
38.
We revisit the classic problem of preemptive scheduling on m uniformly related machines. In this problem, jobs can be arbitrarily split into parts, under the constraint that every job is processed completely, and that the parts of a job are not assigned to run in parallel on different machines. We study a new objective which is motivated by fairness, where the goal is to minimize the sum of the two maximal job completion times. We design a polynomial time algorithm for computing an optimal solution. The algorithm can act on any set of machine speeds and any set of input jobs. The algorithm has several cases, many of which are very different from algorithms for makespan minimization (algorithms that minimize the maximum completion time of any job), and from algorithms that minimize the total completion time of all jobs.  相似文献   
39.
New models are proposed for the distributions of active slip systems induced by a cone and a ball indentation on the (001) plane of f.c.c. metals. By employing modified elastic stress fields, three or four primary slip systems are predicted to be individually active in the octant bounded by the [110] and [010] axes.The observed slip traces, surface topography and the shape of dislocation clustering zones are shown to be in reasonable agreement with those expected by the activation of the predicted slip systems. It is also shown that the anisotropy of the extent of this plastic region can be related to that of the elastic stress field.  相似文献   
40.
The electronic specific heat Cel was studied in Ga- and Zn-doped La2–xSrxCuO4 (0.16x0.22) at T10K. Partial substitution of Ga or Zn for Cu suppresses Tc and revives the T-linear electronic specific heat, T, markedly. The (y)/n vs Tc/Tc0 relation for Zn-doped samples with x0.2 is in good agreement with the theoretical one for resonant impurity scattering in a d-wave superconductor, while those for Ga-doped samples and for Zn-doped samples with x 0.2 deviate slightly from the theoretical curve. The deviation will be discussed in relation to changes in the magnetic properties of 3d electrons.  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