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   1180篇
  免费   2篇
  国内免费   2篇
电工技术   13篇
化学工业   94篇
金属工艺   4篇
机械仪表   54篇
建筑科学   49篇
矿业工程   3篇
能源动力   1篇
轻工业   344篇
水利工程   8篇
石油天然气   14篇
武器工业   1篇
无线电   216篇
一般工业技术   316篇
冶金工业   3篇
原子能技术   1篇
自动化技术   63篇
  2012年   118篇
  2011年   139篇
  2010年   25篇
  2009年   9篇
  2008年   86篇
  2007年   96篇
  2006年   79篇
  2005年   74篇
  2004年   55篇
  2003年   48篇
  2002年   67篇
  2001年   45篇
  2000年   45篇
  1999年   17篇
  1998年   24篇
  1997年   36篇
  1996年   26篇
  1995年   26篇
  1994年   28篇
  1993年   12篇
  1992年   17篇
  1991年   13篇
  1990年   13篇
  1989年   14篇
  1988年   4篇
  1987年   6篇
  1986年   5篇
  1985年   2篇
  1984年   11篇
  1983年   8篇
  1982年   3篇
  1981年   4篇
  1980年   1篇
  1979年   7篇
  1978年   4篇
  1977年   1篇
  1976年   1篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
  1970年   2篇
  1967年   1篇
  1966年   2篇
  1959年   1篇
  1956年   1篇
  1948年   2篇
  1947年   1篇
排序方式: 共有1184条查询结果,搜索用时 0 毫秒
101.
计算机集成制造设备是能够在不到10min时间内完成优质成品板卷的一个关键设备,该生产过程包括退火、光整冷轧、侧修边剪、检查和准备发货,采用常规的精整设备来完成这一系列生产过程需要10天时间。  相似文献   
102.
简要阐述了网络管理的目标、网络管理技术的演进;在电信网络管理(TMN)的框架下的网络管理和新动向;一些针对公司网络的网络管理解决方案。  相似文献   
103.
Recent progress in magnetic resonance electrical impedance tomography (MREIT) research via simulation and biological tissue phantom studies have shown that conductivity images with higher spatial resolution and accuracy are achievable. In order to apply MREIT to human subjects, one of the important remaining problems to be solved is to reduce the amount of the injection current such that it meets the electrical safety regulations. However, by limiting the amount of the injection current according to the safety regulations, the measured MR data such as the z-component of magnetic flux density Bz in MREIT tend to have low SNR and get usually degraded in their accuracy due to the nonideal data acquisition system of an MR scanner. Furthermore, numerical differentiations of the measured Bz required by the conductivity image reconstruction algorithms tend to further deteriorate the quality and accuracy of the reconstructed conductivity images. In this paper, we propose a denoising technique that incorporates a harmonic decomposition. The harmonic decomposition is especially suitable for MREIT due to the physical characteristics of Bz. It effectively removes systematic and random noises, while preserving important key features in the MR measurements, so that improved conductivity images can be obtained. The simulation and experimental results demonstrate that the proposed denoising technique is effective for MREIT, producing significantly improved quality of conductivity images. The denoising technique will be a valuable tool in MREIT to reduce the amount of the injection current when it is combined with an improved MREIT pulse sequence.  相似文献   
104.
Wi-Fi概述 1.标准及特点 Wi-Fi(Wireless Fidelity,无线保真)是属于无线局域网(WLAN)的一种,通常是指IEEE802.11b产品,是利用无线接人手段的新型局域网解决方案。Wi-Fi的主要特点是传输速率高、可靠性高、建网快速,简便、可移动性好、网络结构弹性化、组网灵活、组网价格较低等,它具有良好的发展前景。  相似文献   
105.
近年来,全球DSL(数字用户环路)的增长速度在经过短短的停滞后又活跃起来.到2002年第一季度,全球DSL用户已增加到2 370万户,预计到2004年亚洲还会增加330万户,这样和Cable Modem(电缆调制解调器)用户数相比将会接近2:1.  相似文献   
106.
The method of laser Doppler vibrometry (LDV) is used to sense movements of the skin overlying the carotid artery. When pointed at the skin overlying the carotid artery, the mechanical movements of the skin disclose physiological activity relating to the blood pressure pulse over the cardiac cycle. In this paper, signal modeling is addressed, with close attention to the underlying physiology. Segments of the LDV signal corresponding to single heartbeats, called LDV pulses, are extracted. Hidden Markov models (HMMs) are used to capture the dynamics of the LDV pulses from beat to beat based on pulse morphology; under resting conditions these dynamics are primarily due to respiration-related effects. LDV pulses are classified according to state, by computing the optimal state path through the data using trained HMMs. HMM state dynamics are examined within the context of respiratory effort using strain gauges placed around the abdomen. This study presented here provides a graphical model approach to modeling the dependence of the LDV pulse on latent states.  相似文献   
107.
108.
109.
Objectives were to determine the effects of feeding whole linted Upland (WUP) and cracked Pima cottonseed (BUPCP) to lactating cows on plasma gossypol concentrations and lactation performance. Holstein cows (n = 813) from three commercial dairies were assigned to one of two diets starting at 13+/-11 d in milk (DIM) for a 170-d experimental period. Cottonseed was included at 10% of the diet dry matter, and treatments consisted of replacing WUP with a 1:2 blend of BUPCP. Blood was collected from all cows at 61 and 91 DIM and from a subset of 56 cows on one dairy at 10, 33, 61, 91, 120, and 152 DIM. Intakes of free gossypol increased 32% in cows receiving the BUPCP diet, and concentrations of total gossypol (TG), as well as the proportion of TG as minus (-) isomer in plasma, were higher for cows fed BUPCP than WUP. Plasma TG increased linearly with increasing DIM, but cows fed the BUPCP, especially multiparous cows, had a higher increase in plasma TG over time. Yields of milk and milk components did not differ between the two treatments, although, yields of milk and milk components were greater in cows with higher plasma TG. Replacement of WUP cottonseed with BUPCP cottonseed increased plasma gossypol, but dry matter intake and yields of milk and milk components were not affected.  相似文献   
110.
We have developed a new nonradioactive assay to identify human low-density lipoprotein receptor defects. It is based on the incubation of cultured cells with colloidal gold-LDL conjugates and quantitation of the gold associated with the cells by electrothermal atomic absorption spectrometry. After an oxidative treatment with nitric and hydrochloric acids, the biological matrix interferes neither with the gold recovery nor with the gold measurements, which are linear, at least from 0.15 to 3 ng of gold. When cells expressing a functional LDL receptor are incubated with increasing amounts of colloidal-gold LDL conjugates, the obtained saturation curve parallels that described when [125I]LDL is used as ligand. Moreover, this new assay allows us to clearly distinguish among fibroblasts from normal subjects or from heterozygous or homozygous patients of familial hypercholesterolemia, a very common autosomal disease. The assay is easy to perform, is sensitive, and avoids the use of radioactive compounds. Therefore, it could be successfully employed in the clinical diagnosis of this disease. Furthermore, since the methodology developed here can be applied to quantify the association of other gold-conjugated ligands to cells, it could have a widespread use in a variety of clinical and basic research studies.  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