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   205篇
  免费   8篇
电工技术   8篇
化学工业   22篇
金属工艺   1篇
机械仪表   4篇
建筑科学   10篇
能源动力   3篇
轻工业   9篇
水利工程   3篇
无线电   42篇
一般工业技术   27篇
冶金工业   62篇
原子能技术   3篇
自动化技术   19篇
  2024年   1篇
  2022年   4篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   4篇
  2016年   10篇
  2015年   3篇
  2014年   4篇
  2013年   3篇
  2012年   2篇
  2011年   9篇
  2010年   3篇
  2009年   3篇
  2008年   8篇
  2007年   7篇
  2006年   4篇
  2005年   10篇
  2004年   4篇
  2003年   11篇
  2002年   6篇
  2001年   7篇
  2000年   7篇
  1999年   3篇
  1998年   25篇
  1997年   13篇
  1996年   8篇
  1995年   8篇
  1994年   5篇
  1993年   4篇
  1992年   4篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
  1981年   5篇
  1980年   2篇
  1978年   1篇
  1976年   3篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1971年   1篇
排序方式: 共有213条查询结果,搜索用时 15 毫秒
121.
In a double-blind, multicentre study 245 children aged 1-10 yr undergoing elective minor surgery as inpatients were randomly allocated to receive a single caudal extradural injection of 1 ml kg-1 of either 0.25% bupivacaine or 0.2% ropivacaine after induction of light general anaesthesia. The groups were comparable for age, weight, vital signs and duration of surgery. The onset time was similar for ropivacaine and bupivacaine (9.7 vs 10.4 min). Further analgesia was not required in 40% of children. The mean time to first analgesia in the remainder was 233 min in the bupivacaine group and 271 min in the ropivacaine group. No motor block was measurable in either group. Ropivacaine 2 mg kg-1 was as effective as bupivacaine 2.5 mg kg-1 for caudal analgesia in children.  相似文献   
122.
The Object-Blog service application automatically converts raw sensor data to environment-generated content (EGC), including texts, graphs, and figures. This conversion facilitates data searching and browsing. Generated content can serve several purposes, including memory aids, security, and communication media. In Object-Blog, personified objects automatically post entries to a weblog about sensor data obtained from sensors attached to the objects. Feedback thus far from participants working with Object-Blog in an experimental environment has been positive.  相似文献   
123.
We assessed the effect of diabetes on antinociception produced by intracerebroventricular injection of delta-opioid receptor agonists [D-Pen2,5]enkephalin (DPDPE) and [D-Ala2]deltorphin II. The antinociceptive effect of DPDPE (10 nmol), administered i.c.v., was significantly greater in diabetic mice than in non-diabetic mice. The antinociceptive effect of i.c.v. DPDPE was significantly reduced in both diabetic and non-diabetic mice following pretreatment with 7-benzylidenenaltrexone (BNTX), a selective delta 1-opioid receptor antagonist, but not with naltriben (NTB), a selective delta 2-opioid receptor antagonist. There were no significant differences in the antinociceptive effect of [D-Ala2]deltorphin II (3 nmol, i.c.v.) in diabetic and non-diabetic mice. Furthermore, the antinociceptive effect of i.c.v. [D-Ala2]deltorphin II was significantly reduced in both diabetic and non-diabetic mice following pretreatment with NTB, but not with BNTX. In conclusion, mice with diabetes are selectively hyper-responsive to supraspinal delta 1-opioid receptor-mediated antinociception, but are normally responsive to activation of delta 2-opioid receptors.  相似文献   
124.
125.
A highly interactive operator workstation for a distribution automation system using spatial data management was developed. The spatial data structure, called MD-tree, manages a large amount of equipment data and its background map data hierarchically. By its rapid range searching and the related techniques, fast response time and a user-friendly interface are obtained on a reduced instruction set computer (RISC) workstation without a hardware accelerator. The system configuration, the graphic data management method using the MD-tree, and the sophisticated graphic functions and operations are described  相似文献   
126.
Rats exhibited a marked suppression of motility when they were re-placed in the same environment as that in which they had previously received an electric footshock. We examined the behavioral and neurochemical effects of (+)-N-allylnormetazocine hydrochloride ((+)-SKF-10,047) and (+)-pentazocine, putative sigma 1 receptor ligands, on this psychological-stress-induced motor suppression, defined as a conditioned fear stress. (+)-SKF-10,047 (3 and 6 mg/kg) dose-dependently attenuated the conditioned fear stress, whereas (+)-pentazocine failed to do so even at a higher dose (32 mg/kg). In rats showing the conditioned fear stress, dopamine turnover (i.e., the ratio of dopamine metabolites/dopamine contents) was decreased in the nucleus accumbens and was increased in the medial prefrontal cortex, but remained unchanged in the striatum. (+)-SKF-10,047 (3 and 6 mg/kg) dose-dependently reversed the decreased dopamine turnover in the nucleus accumbens without changing the increased dopamine turnover in the medial prefrontal cortex. (+)-Pentazocine (32 mg/kg) did not affect the stress-induced changes in dopamine turnover in these brain regions. Thus, the decreased dopamine turnover in the nucleus accumbens appears to be involved in the conditioned fear stress. These results suggest that (+)-SKF-10,047 ameliorates the conditioned fear stress by reversing the psychological stress-induced dysfunction in the mesolimbic dopaminergic systems, and that the (+)-SKF-10,047-sensitive sub-population of sigma 1 receptors may play in important role in this stress response.  相似文献   
127.
We conducted x-ray crystal truncation rod (CTR) measurements using synchro-tron radiation to analyze the As atom distribution in InP to the order of 1 ML. The InP samples which were only exposed to AsH3(+PH3) and capped by InP were investigated to study the effect of the purge sequence. The purge sequence is unavoidable to grow heteroepitaxial layers by OMVPE and is considered to affect largely the structure of the interface. From the results of the measurement and the computer simulation, the distribution of P and As atoms of the order of 1 ML was discussed as functions of the exposing time. It was shown that the number of As atoms contained in the samples saturated when the AsH3-exposure time is longer than 10 s. Comparing the profiles of AsH3-exposed samples with that of (AsH3 + PH3)-exposed samples, it was found that the As distribution in the buffer layer was suppressed in (AsH3 + PH3)-exposed samples. In order to obtain the sharp interfaces, the AsH3-exposure time must be shorter than 0.5 s.  相似文献   
128.
Electrodeposited Fe–P amorphous alloy has been characterized in terms of magnetic properties and the microstructure. The Fe–P electrodeposits show amorphous structure with phosphorus contents of about 20 at%. The formation of the amorphous structure depends mainly on the phosphorus content. The amorphous Fe–P alloy shows typical soft magnetic properties such as low coercive force and high permeability. The coercive force (Hc) decreases with the low temperature annealing, and the lowestHc is about 0.05 oersted. This reduction inHc can be attributed to structural relaxation. The amorphous phase is crystallized at temperatures above 300°C accompanying a drastic increase inHc. The stable crystalline phase is Fe3P.  相似文献   
129.
Structures of silica nanoparticles coated with stereocomplex thin films composed of isotactic (it) poly(methyl methacrylate) (PMMA) and syndiotactic (st) poly(methacrylic acid) (PMAA) and with porous it-PMMA thin films under gentle stirring or static conditions were analyzed by dynamic light scattering (DLS) and scanning electron microscopy (SEM), respectively. The porous it-PMMA films were fabricated by stepwise stereocomplex assembling of it-PMMA and st-PMAA, and subsequent extraction of the st-PMAA from the films. From DLS results, an evident difference was not observed between the it-PMMA films and the stereocomplex films, whereas the it-PMMA films after 10 h of stirring in acetonitrile/water (4/6, v/v) and drying on a SEM stage fused to form nanostructured networks. The fusion of the it-PMMA films on the silica nanoparticles occurred not by the dissolution of it-PMMA in the mixed solvent, but rather by an interaction of the it-PMMA chains driven by the slight solvation of acetonitrile without dissolution. Thus, leaving the solution at rest would be important for film fusion on the particles, and multiple spherical substrates could promote the crosslinking of the it-PMMA chains on the particles.  相似文献   
130.
Condition‐Based Maintenance (CBM) is a new maintenance strategy and interest of utilities for reliable operation of aged power equipment. Although attempts have been made to apply CBM to various types of equipment, owing to insufficient understanding of the effect of the accuracy of condition information provided by sensors, the specification of reliable information is still not clear and CBM has not been widely applied in real power substations. The effect of the accuracy of condition information on the criteria of failure recognition is treated in this paper. The potential failure curve (P‐F curve) used in the original Reliability‐Centered Maintenance (RCM) concept is studied and its effect is explained. The explanation is confirmed by comparison of proved original sensors for CBM and existing sensors in an SF6 gas slow leakage detection experiment. The experiment indicates that SF6 gas leakage at levels of less than 0.1% per year might be detected with a CBM sensor. It is concluded that special efforts should be devoted to the sensitivity and long‐term stability of sensors for reliable operation of power substations under the CBM strategy. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 176(2): 14–21, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21114  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