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   256篇
  免费   9篇
电工技术   11篇
综合类   1篇
化学工业   61篇
金属工艺   9篇
机械仪表   7篇
建筑科学   4篇
能源动力   3篇
轻工业   40篇
水利工程   2篇
无线电   18篇
一般工业技术   46篇
冶金工业   33篇
原子能技术   17篇
自动化技术   13篇
  2023年   1篇
  2022年   2篇
  2021年   7篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   5篇
  2016年   8篇
  2015年   8篇
  2014年   10篇
  2013年   15篇
  2012年   8篇
  2011年   15篇
  2010年   15篇
  2009年   19篇
  2008年   12篇
  2007年   14篇
  2006年   5篇
  2005年   11篇
  2004年   13篇
  2003年   9篇
  2002年   9篇
  2001年   6篇
  2000年   3篇
  1999年   7篇
  1998年   12篇
  1997年   6篇
  1996年   6篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1991年   2篇
  1990年   3篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1981年   2篇
  1979年   3篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1971年   1篇
排序方式: 共有265条查询结果,搜索用时 109 毫秒
1.
Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint.  相似文献   
2.
Hot carrier magnetophonon resonances of n-type Si, short channel InP and p-type InSb were investigated in pulsed high magnetic fields up to 40 T. Using a recently developed high resolution technique in pulsed high fields, many new features of the hot carrier-phonon interactions in high magnetic fields were found.  相似文献   
3.
4.
Chitin membrane was prepared by casting a N,N-dimethyl acetamide, N-methyl 2-pyrrolidone and lithium chloride (DMA-NMP-LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2-Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2-propanol and water. The membrane obtained in 2-propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms of crystallinity.  相似文献   
5.
6.
7.
Quick-freeze deep-etch replica electron microscopy gives high contrast snapshots of individual protein molecules under physiological conditions in vitro or in situ. The images show delicate internal pattern, possibly reflecting the rotary-shadowed surface profile of the molecule. As a step to build the new system for the "Structural analysis of single molecules", we propose a procedure to quantitatively characterize the structural property of individual molecules; e.g. conformational type and precise view-angle of the molecules, if the crystallographic structure of the target molecule is available. This paper presents a framework to determine the observed face of the protein molecule by analyzing the surface profile of individual molecules visualized in freeze-replica specimens. A comprehensive set of rotary-shadowed views of the protein molecule was artificially generated from the available atomic coordinates using light-rendering software. Exploiting new mathematical morphology-based image filter, characteristic features were extracted from each image and stored as template. Similar features were extracted from the true replica image and the most likely projection angle and the conformation of the observed particle were determined by quantitative comparison with a set of archived images. The performance and the robustness of the procedure were examined with myosin head structure in defined configuration for actual application.  相似文献   
8.
9.
ABSTRACT: The mastication of 7 differently prepared apple samples (raw pieces peeled and unpeeled, sliced, grated, cooked pieces with and without peel, and half-cooked pieces, 10 g each) was evaluated using electromyography (EMG). Eleven subjects participated in the EMG recording of both sides of the masseter and temporal muscles while eating samples normally. Only the grated sample reduced the number of chewing strokes and muscle activity before swallowing. In contrast, the thin apple slices produced significantly shorter contraction duration and cycle time only during the 1st 5 chewing strokes. The EMG duration and cycle in subsequent chews, as well as the other parameters, did not significantly differ between slices and pieces. Cooked apples exhibited significantly lower EMG amplitude and muscle activity per chew than their raw counterparts; however, there was no evidence of reduced total muscle activity required for swallowing. Raw and cooked apples with peel yielded significantly greater EMG amplitude and longer duration than those without peel. These findings suggest that appropriate preparation is necessary for people with various mastication abilities: grated for very low ability, cooked for those with weak chewing force, and unpeeled for mastication training.  相似文献   
10.
Atomic resolution high voltage electron microscopy was applied in investigations of the atomic structure of [112] sigma3 CSL grain boundary of silicon. Images of the grain boundary, viewed in the < 110 > direction, showed two types of dark spots. One type was rod shaped, which represented an atomic pair aligned in the < 111 > direction. The other was a small round spot, which represented a single atomic column in the grain boundary. The atomic structure of [112] sigma3 CSL grain boundary was directly shown from the atomic-structure image.  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