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   1005篇
  免费   13篇
  国内免费   1篇
电工技术   55篇
综合类   1篇
化学工业   216篇
金属工艺   21篇
机械仪表   13篇
建筑科学   15篇
矿业工程   2篇
能源动力   17篇
轻工业   98篇
水利工程   2篇
石油天然气   1篇
无线电   119篇
一般工业技术   111篇
冶金工业   246篇
原子能技术   32篇
自动化技术   70篇
  2021年   10篇
  2018年   16篇
  2017年   7篇
  2016年   12篇
  2014年   7篇
  2013年   40篇
  2012年   27篇
  2011年   32篇
  2010年   28篇
  2009年   21篇
  2008年   25篇
  2007年   30篇
  2006年   37篇
  2005年   28篇
  2004年   23篇
  2003年   22篇
  2002年   17篇
  2001年   23篇
  2000年   19篇
  1999年   22篇
  1998年   95篇
  1997年   52篇
  1996年   30篇
  1995年   30篇
  1994年   30篇
  1993年   32篇
  1992年   17篇
  1991年   9篇
  1990年   10篇
  1989年   14篇
  1988年   13篇
  1987年   10篇
  1986年   7篇
  1985年   11篇
  1983年   8篇
  1982年   10篇
  1980年   8篇
  1979年   8篇
  1978年   6篇
  1977年   9篇
  1976年   13篇
  1974年   6篇
  1972年   15篇
  1971年   12篇
  1961年   12篇
  1960年   11篇
  1959年   11篇
  1958年   12篇
  1957年   13篇
  1955年   10篇
排序方式: 共有1019条查询结果,搜索用时 0 毫秒
1.
2.
Polymerase chain reaction (PCR) with nested primer pairs was used to diagnose scrub typhus and identify the Rickettsia tsutsugamushi serotype. The primer pairs used for PCR were designed on the basis of the nucleotide sequence of the gene that encodes the 56-kDa antigen. Serotype-specific primers were used in the second PCR amplification. Five serovariants, the Gilliam, Karp, Kato, Kawasaki, and Kuroki strains of R. tsutsugamushi, were identified by nested PCR. In addition, the serotype identified by PCR with DNA from blood clots was the same as that of the strain isolated from five patients with scrub typhus. These findings indicate that this method is useful for diagnosis and identification of the rickettsial serotype in infected patients.  相似文献   
3.
Radiation detector was made of a high-quality CVD polycrystalline diamond composed of frost column like structure diamond grains, and induced charge distribution spectra and drift velocities were measured by using alpha particles. As a result, the CVD polycrystalline achieved maximum induced charge of 83% of HP/HT type IIa diamond. Moreover, the CVD crystal had lower charge loss on electrons compared with the HP/HT type IIa diamond. Drift velocities of electrons and holes were ve = 7.7 × 104 and vh = 7.3 × 104cm/s at an electric field of 20 kV/cm, respectively. In addition, response function measurement for 14 MeV neutrons was carried out.  相似文献   
4.
5.
6.
The authors reports the fabrication of a flip-chip InGaAsP-InAlAs superlattice avalanche photodiode using gas source molecular beam epitaxy. The incident light reaches the InGaAs photoabsorption layer through the InP substrate and an InGaAsP-InAlAs superlattice multiplication region which are transparent for wavelengths of 1.55 and 1.3 μm. The light reflection by the electrode enables the absorption layer to be as thin as 0.8 μm without significantly reducing the quantum efficiency. A maximum bandwidth of 17 GHz was obtained at a low multiplication factor because the transit time through the absorption layer is reduced  相似文献   
7.
本文是<时尚学:时尚研究概述>(Fashion-ology:An Introduction to Fashion Studies)一书的前言部分,概括了书中的一些主要观点.作者认为应该将对时尚的研究与对衣着的研究区分开来.时尚无关服饰,它只是一种信仰.她主张应该把时尚研究列入社会科学、人文科学的研究范围内,并介绍了人们在心理学、社会心理学、历史学、艺术史、文化人类学和经济学等领域对时尚的研究.她所提倡的时尚理论认为,对时尚的研究应该从时尚系统入手,研究它整个运作过程中的社会属性.  相似文献   
8.
In this paper, we describe an improved particle-based volume rendering (PBVR) technique for previewing a large irregular volume dataset using the CUDA architecture. This technique allows for opaque and emissive particles to render translucent volumes without visibility sorting. Our GPU acceleration of PBVR provides the multi-volume rendering feature while remaining compatible with both regular and irregular volumes. We also reduce the memory cost required for storing all sub-pixel values by proposing a pixel repetition technique for a large sub-pixel level. By adjusting the repetition level, we achieved a very smooth level of detail (LOD) control for trading quality for speed. Our work demonstrates a full-detail rendering rate from 5 to 10 fps for irregular volume data with mega-scale cell numbers on an NVIDIA GeForce 8800GTS.  相似文献   
9.
In a half-zone (HZ) liquid bridge, flow exhibits a transition from a two-dimensional steady to a three-dimensional oscillatory flow if the Marangoni number Ma exceeds a critical value Mac, or ΔT>ΔTc. In case of high Prandtle number fluids, the Mac obtained in the numerical simulations deviated significantly from the ones by the experiments. One of the causes of the difference is due to the heat loss over the free surface. Most of past researches neglected effects of the heat loss through an interface of the liquid bridge. Recently several experimental and analytical works reported that the critical condition is significantly affected by the heat loss. The present study aims to include the effects of the heat loss upon the Mac. As the result, the calculated Mac agrees well with the experiment for a high Pr fluid.  相似文献   
10.
Based on fungal and fumonisin contamination of 870 freshly harvested samples, the quality of corn used by processing industries in the Northern region of Paraná State, Brazil (2003 and 2004 crop-year) was evaluated. Sampling was carried out for each crop at two points in the production chain, i.e. at reception by the processors and at the pre-drying step. Corn samples were more frequently contaminated with Fusarium sp. (100%) and Penicillium sp. (84.1–95.3%) than Aspergillus sp. (5.6–19.8%). Fumonisin B1 (FB1) was detected in all samples from the two points in both crop-years. FB1 levels ranged 0.02–11.83 µg g?1 in the reception and 0.02–10.98 µg g?1 in the pre-drying samples of the 2003 crop. Samples from the 2004 crop showed FB1 levels ranging 0.03–12.04 µg g?1 in the reception and 0.06–7.74 µg g?1 in the pre-drying samples. FB2 levels ranged 0.02–5.25 µg g?1 in the reception and 0.01–7.89 µg g?1 in the pre-drying samples (2003 crop-year). In samples from the 2004 crop, FB2 levels ranged 0.02–6.12 µg g?1 in the reception and 0.05–3.47 µg g?1 in the pre-drying samples. Low fumonisin levels were detected in most corn samples used by processors in the Northern region of Paraná State, showing a decreasing trend in fumonisin contamination over the years.  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