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   220篇
  免费   2篇
电工技术   4篇
化学工业   29篇
金属工艺   8篇
机械仪表   1篇
建筑科学   13篇
矿业工程   3篇
能源动力   5篇
轻工业   45篇
石油天然气   1篇
无线电   14篇
一般工业技术   30篇
冶金工业   36篇
原子能技术   1篇
自动化技术   32篇
  2023年   4篇
  2022年   5篇
  2021年   9篇
  2020年   3篇
  2019年   6篇
  2018年   7篇
  2017年   9篇
  2016年   3篇
  2015年   6篇
  2014年   6篇
  2013年   18篇
  2012年   14篇
  2011年   14篇
  2010年   9篇
  2009年   6篇
  2008年   14篇
  2007年   3篇
  2006年   6篇
  2005年   8篇
  2004年   8篇
  2003年   4篇
  2002年   9篇
  2001年   3篇
  2000年   8篇
  1999年   1篇
  1998年   7篇
  1997年   6篇
  1996年   2篇
  1995年   2篇
  1993年   1篇
  1992年   2篇
  1988年   1篇
  1987年   4篇
  1985年   2篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1977年   1篇
  1976年   3篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1966年   1篇
排序方式: 共有222条查询结果,搜索用时 15 毫秒
31.
32.
33.
正科帕卡格拉纳位于新多瑙河12.5公里处,毗邻Reichsbrücke大桥。出于同旧有设计保持协调性考虑,力求能让大楼融入当地环境,迎合自身功能性需要,GERNER GERNER PLUS团队充分考虑现有周边环境,对大楼重新规划设计。新的设计突显建筑的特殊性和重要性,面向河流的立面是科帕卡格拉纳大楼最重要的部分,所以设计的重点也放在了这里。现有的城市中轴线是一个参照物,为了视觉上和氛围上形成一体化城市的感  相似文献   
34.
We report the experimental realization of efficient tunable nanosources of second harmonic light with individual multiresonant log-periodic optical antennas. By designing the nanoantenna with a bandwidth of several octaves, simultaneous enhancement of fundamental and harmonic fields is observed over a broad range of frequencies, leading to a high second harmonic conversion efficiency, together with an effective second order susceptibility within the range of values provided by widespread inorganic crystals. Moreover, the geometrical configuration of the nanoantenna makes the generated second harmonic signal independent from the polarization of the fundamental excitation. These results open new possibilities for the development of efficient integrated nonlinear nanodevices with high frequency tunability.  相似文献   
35.
A random sample of licensed psychologists from Illinois (N=286) responded to a survey about career-sustaining behaviors (CSBs) and about satisfactions and stresses they experience at work. The highest rated CSBs were spending time with partner/family, maintaining a balance between personal and professional lives, and maintaining a sense of humor. Overall, more satisfied respondents reported greater importance of CSBs. Female respondents reported significantly greater use of CSBs than male respondents and were more likely to endorse behaviors that were relational or educational in nature, such as participating in personal therapy, spending time with friends, discussing work frustrations with colleagues, seeking case consultation, maintaining regular contact with referral networks, participating in continuing-education programs, reflecting on positive experiences, and engaging in quiet leisure activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
36.
37.
38.
Magnetic resonance imaging (MRI) is unique in its ability to noninvasively and selectively alter tissue magnetization and create tagged patterns within a deforming body such as the heart muscle. The resulting patterns define a time-varying curvilinear coordinate system on the tissue, which the authors track with coupled B-snake grids. B-spline bases provide local control of shape, compact representation, and parametric continuity. Efficient spline warps are proposed which warp an area in the plane such that two embedded snake grids obtained from two tagged frames are brought into registration, interpolating a dense displacement vector field. The reconstructed vector field adheres to the known displacement information at the intersections, forces corresponding snakes to be warped into one another, and for all other points in the plane, where no information is available, a C1 continuous vector field is interpolated. The implementation proposed in this paper improves on the authors' previous variational-based implementation and generalizes warp methods to include biologically relevant contiguous open curves, in addition to standard landmark points. The methods are validated with a cardiac motion simulator, in addition to in-vivo tagging data sets  相似文献   
39.
The goal of the present study was to quantify the increase of intramammary pressure (IMP) in dry-off during an extended milking interval of 72 h. In particular, we tested the hypothesis that feed restriction (no concentrate and roughage with reduced energy) causes earlier cessation of milk secretion and a lower IMP than continued feeding of the lactational diet. In addition to repeated IMP measurements, we tested a noninvasive method that records udder firmness (UF) via external application of pressure on the udder. Two experimental groups consisted of 10 Holstein cows each, with a daily milk yield of 20 to 25 kg. The restricted group (RG) was changed to restricted feeding on the afternoon of the final milking (0 h), whereas late-lactation feeding was continued in the control group (CG). Both IMP and UF were measured before and after the final milking immediately before milking was stopped for 72 h. These measurements represented IMP and UF levels at 10 h and 0 h milking intervals, respectively. Further measurements were performed at 18, 24, 30, 36, 42, 48, and 72 h after final milking. Milk samples (2 mL) were taken through the IMP catheter at each sampling event, for analysis of somatic cell count (SCC) and serum albumin (SA). Both IMP and UF increased with time, and both parameters peaked at 30 h in CG and at 24 h in RG. The mean IMP from 18 to 72 h, compared with the 10-h IMP (normal milking interval) was higher in CG than in RG. The duration of elevated IMP and UF was prolonged in CG compared with RG (>36 h vs. 12 h). The Pearson correlation between IMP and UF was r = 0.67. Thus, the noninvasive measurement of UF is suitable to replace invasive IMP measurements. However, due to individual differences in udder shape, the correlation between UF and IMP was too low to predict exact IMP levels using UF. Both SCC (presented as logSCC) and SA increased after the final milking until the end of the experiment. The mean increase from 18 to 72 h, compared with levels immediately after final milking, was higher in CG than in RG for SCC but did not differ between treatments for SA. In conclusion, feed restriction causes a faster cessation of milk secretion and therefore limits the increase of IMP at dry-off.  相似文献   
40.
The aim of this study was to test if the opioid antagonist naloxone has a beneficial effect on normalization of oxytocin (OT) release during repeated milking of cows in unfamiliar surroundings. One control milking without naloxone treatment in all cows was performed in the familiar parlour. For four successive evening milkings, cows were transported to, and milked in, the operating theatre of the research station without (control group) or with naloxone administration (1 mg/kg BW) (naloxone group) before milking. After cessation of spontaneous milk flow, but not before 3 min of milking, vaginal stimulation was applied for 2 min. After milk flow ceased again, 10 IU of OT was injected intravenously to remove the remaining milk including residual milk. Milk flow was recorded continuously and blood samples were collected via a jugular vein cannula at 1-min intervals from 1 min before the start of milking until i.v. injection of OT. The inhibition of milk ejection and its normalization during repeated milking in unfamiliar surroundings was not influenced by naloxone treatment. Concentrations of cortisol and beta-endorphin during control milking and all relocations were similar in the naloxone and control groups, although their concentrations were higher after relocations than in the control. Therefore, a role of endogenous opioids in the inhibition of milk ejection in unfamiliar surroundings could not be demonstrated. In addition, the effect of exogenous ACTH1-24 (8 IU, i.v.) on the release of cortisol related to the response of cows milked in unfamiliar surroundings was studied. Cows with totally inhibited milk ejection in response to vaginal stimulation during milking after first relocation had numerically, but not significantly lower cortisol levels (8.8+/-3.4 ng/ml; AUC/min) in response to ACTH than did cows with at least partial milk ejection (38.7+/-12.9 ng/ml). Thus animals with a higher adrenal response to ACTH seemed to have less severe inhibition of milk ejection.  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