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   783篇
  免费   53篇
  国内免费   36篇
电工技术   8篇
综合类   27篇
化学工业   301篇
金属工艺   26篇
机械仪表   83篇
建筑科学   5篇
矿业工程   1篇
轻工业   164篇
武器工业   2篇
无线电   55篇
一般工业技术   32篇
冶金工业   47篇
原子能技术   12篇
自动化技术   109篇
  2024年   2篇
  2023年   10篇
  2022年   110篇
  2021年   128篇
  2020年   16篇
  2019年   19篇
  2018年   15篇
  2017年   24篇
  2016年   25篇
  2015年   29篇
  2014年   35篇
  2013年   45篇
  2012年   59篇
  2011年   45篇
  2010年   22篇
  2009年   33篇
  2008年   44篇
  2007年   37篇
  2006年   21篇
  2005年   29篇
  2004年   20篇
  2003年   23篇
  2002年   16篇
  2001年   13篇
  2000年   5篇
  1999年   3篇
  1998年   8篇
  1997年   5篇
  1996年   1篇
  1995年   5篇
  1994年   3篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   2篇
  1989年   3篇
  1987年   3篇
  1986年   1篇
  1984年   1篇
  1981年   2篇
  1964年   1篇
  1956年   1篇
排序方式: 共有872条查询结果,搜索用时 31 毫秒
51.
House mice release chemosignals in their urine that influence the timing of puberty and reproductive condition in conspecific females. These experiments tested the possibility that mice depositing urine containing chemosignals that affect puberty and reproduction do so differentially with respect to urine cues from conspecifics. Mice were tested in cages containing samples of urine or water on cotton in wire mesh capsules protruding from the cage floor. Their urine deposition patterns were recorded on squares of filter paper positioned below the cages. Males deposited more urine than females housed in groups, estrous females, diestrous females, or prepubertal females. All groups of mice deposited urine in a nonrandom fashion with regard to urine cues from conspecifics. Male mice deposited more urine near locations previously soiled by females than near water or other males. Grouped females deposited more urine near male urine cues and avoided depositing urine near urine from other group-housed females. Both estrous and diestrous female mice deposited more urine near males than near other urine cues or water, possibly to attract mates. Prepubertal females avoided depositing their urine near male urine and urinated more near urine from grouped females than near other urine types or water. Young females may be avoiding possible male mates until they have attained puberty. This avoidance behavior may enhance the long-term reproductive success of the females that otherwise might mature and mate at too young an age.  相似文献   
52.
目的:He-Ne激光对妊娠母鼠进行照射后,观察对其子代的致变效应。方法:取雌雄小白鼠若干。当母鼠怀孕后开始进行激光照射,随机分成4组,照射时间为0,10,30,60min。当子鼠出生30d后,对其进行生长和行为的观察。结果:不同剂量的He-Ne激光照射妊娠母鼠,其子代的体重,学习记忆力、耐寒能力和缺氧环境适应能力有所不同。结论:He-Ne激光对生物体的致变效应是存在的,且与激光的剂量有关。  相似文献   
53.
田丰 《电视技术》2014,38(8):60-64
通过介绍基于视觉的空间定位方法,解释了真三维立体鼠标的实现原理,搭建了真三维立体鼠标系统。针对真三维立体鼠标的空间静态与动态抖动问题,研究了真三维立体鼠标的去抖方法。为了实现两点触控,提出了鬼点去除方法,实现了两个指尖的位置识别。实验证明,在不需要佩戴任何标记和传感器的条件下,基于视觉的立体鼠标能够在真三维显示器上准确绘制图形且不受室内环境光干扰。  相似文献   
54.
文建  黄小洋  吴士明 《激光杂志》2014,(3):79-79,81
目的:观察鼠神经生长因子联合椎旁神经根阻滞治疗肺癌併发带状疱疹神经痛的临床疗效。方法:将40例具有典型带状疱疹神经痛表现的肺癌患者随机分为A组(实验组)和B组(对照组)各20例。治疗组给予鼠神经生长因子肌注1支每日一次+椎旁神经根阻滞每周2次;对照组给予椎旁神经阻滞每周2次。观察治疗后1周、2周疼痛指标及1月后的随访结果。结果:比较两组患者的疼痛指标及总体疗效,A组优于B组,有显著性意义P0.05。结论:鼠神经生长因子联合椎旁神经根治疗肺癌伴带状疱疹神经痛优于单纯椎旁神经阻滞治疗。  相似文献   
55.
刘旭辉  陈牧  李青 《机电工程》2011,28(1):90-93
针对使用键盘和鼠标时存在的一些问题,为了减少操作者的手、肩、颈等部位肌肉疲劳和视觉疲劳,以及提高输入效率,基于人机工程学、心理学、生理学等原理,从颜色、形态、功能、寓意等方面出发,为18~30岁的青年人设计了一种更具人性化的键盘.通过对现有产品和文献的调查,确定了将键盘和鼠标联系在一起进行设计的设计思路.通过调整键盘和...  相似文献   
56.
一种3D无线鼠标设计的新思路,以凌阳单片机为核心控制器,通过MEMS加速度传感器和触控模块,感知鼠标的移动动作,同时,通过无线射频完成无线通信,从而实现鼠标功能。使用过程中,鼠标不仅可以放于载体使用,而且可以在空中使用,增添了鼠标的操控方式,同时,大大增加了此无线鼠标的适用范围。  相似文献   
57.
垂直鼠标设计中的人机工程学应用分析   总被引:1,自引:0,他引:1  
杨磊 《包装工程》2011,32(8):56-58
以多彩科技生产的垂直鼠标为研究对象,通过与传统平放鼠标的人机设计对比分析,论述了由于鼠标革命的产物——垂直鼠标的熨斗形外观设计及右侧面的按键巧妙布置,进而消除了传统平放鼠标人机设计缺陷造成使用者手臂长期不适的状况,总结了垂直鼠标在人机设计中的独特之处,为设计师在产品设计中换位思考提供了新的思路和方法。  相似文献   
58.
The triple-transgenic mouse line (3×Tg-AD) harboring PS1M146V, APPSwe, and taup301L transgenes represents the only transgenic model for Alzheimer's disease (AD) to date capturing both β-amyloid and tau neuropathology. The present study provides an extensive behavioral characterization of the 3×Tg-AD mouse line, evaluating the emergence of noncognitive and cognitive AD-like symptoms at two ages corresponding to the early (6-7 months) and advanced (12-13 months) stages of AD-pathology. Enhanced responsiveness to aversive stimulation was detected in mutant mice at both ages: the 3×Tg-AD genotype enhanced acoustic startle response and facilitated performance in the cued-version of the water maze. These noncognitive phenotypes were accompanied by hyperactivity and reduced locomotor habituation in the open field at the older age. Signs of cognitive aberrations were also detected at both ages, but they were limited to associative learning. The present study suggests that this popular transgenic mouse model of AD has clear phenotypes beyond the cognitive domain, and their potential relationship to the cognitive phenotypes should be further explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
59.
激光联用环磷酰胺对荷瘤鼠外周血IgG影响的实验研究   总被引:2,自引:0,他引:2  
以小鼠S180腹水瘤为动物实验模型.对氦氖激光照射与化疗药物环磷酰胺(CYT)联合应用对S180荷瘤鼠外周血IgG含量影响作了系统性研究。应用11.00,14.67和22.00J/cm^2三种剂量氦氖激光照射荷瘤鼠内眼角,同时联合应用化疗药物环磷酰胺,动态监测S180荷瘤鼠外周血IgG含量的变化。结果表明,CYT联合应用氦氖激光照射组IgG含量均高于单纯应用CYT组。  相似文献   
60.
In vitro iontophoretic delivery of nefopam hydrochloride was conducted to study the effects initial drug concentration, pH, ionic strength and viscosity of the donor solutions on the transdermal flux through a hairless mouse skin. Stability of nefopam hydrochloride under the experimental conditions was investigated. Type of electrode, current intensity, electric voltage and electrode distance were evaluated. Appropriate conditions were selected to minimize the potential degradation problems of nefopam hydrochloride during iontophoresis. Results show that the silver/silver chloride electrode provides better drug stability than the platinum electrode. Higher current intensity resulted in faster transdermal flux and therefore better drug permeability. The increase in the drug permeability appears to be proportionally increased as the current intensity increases in the range of 0.253 to 1.265 mA/cm2. The iontophoretic transdermal delivery of nefopam hydrochloride was observed to increase as the drug concentration in the donor site was increased until it's close to the equilibrium concentration. The optimum pH to achieve the best iontophoresis under constant current was determined to be at pH 3.0. This may be due to the highest available charge density of nefopam was achieved at this pH to provide the best conductance. A decrease in the iontophoretic transdermal flux was encountered as an increase in the solution ionic strength due to the increased competition of similar charged ions with the available current. The increase in the donor solution viscosity decreased the conductivity of the ions and hindered the trandermal flux of the drug under iontophoresis.  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