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   185篇
  免费   8篇
化学工业   27篇
金属工艺   2篇
机械仪表   3篇
建筑科学   14篇
能源动力   2篇
轻工业   9篇
水利工程   1篇
无线电   32篇
一般工业技术   19篇
冶金工业   40篇
自动化技术   44篇
  2023年   1篇
  2022年   4篇
  2021年   4篇
  2020年   1篇
  2019年   3篇
  2018年   3篇
  2017年   1篇
  2016年   7篇
  2015年   4篇
  2014年   8篇
  2013年   15篇
  2012年   10篇
  2011年   6篇
  2010年   7篇
  2009年   8篇
  2008年   18篇
  2007年   7篇
  2006年   7篇
  2005年   4篇
  2004年   6篇
  2003年   5篇
  2002年   5篇
  2001年   7篇
  2000年   1篇
  1999年   6篇
  1998年   2篇
  1997年   11篇
  1996年   1篇
  1995年   6篇
  1994年   3篇
  1993年   2篇
  1991年   2篇
  1990年   2篇
  1989年   4篇
  1988年   2篇
  1986年   2篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1980年   2篇
  1976年   2篇
排序方式: 共有193条查询结果,搜索用时 15 毫秒
21.
The Ethiopian fruit fly, Dacus ciliatus, is an oligophagous pest of cucurbit crops, particularly melons, cucumbers, and marrows (summer squash). The present study aimed to identify host attractants for D. ciliatus and was guided by a behavioral bioassay and an electrophysiological assay. We tested volatile compounds from the fruits of a host plant, ripe and unripe Galia melon, Cucumis melo var. reticulates. Both sexes were attracted to melon volatiles. Those of ripe melon were preferred. Gas chromatography-electroantennographic detection analysis of the behaviorally active ripe melon volatiles consistently showed that 14 compounds elicited similar antennal responses from both sexes. Twelve compounds were identified by gas chromatography-mass spectrometry (GC-MS) using GC-MS libraries, retention indices (RI), and authentic standards. The electrophysiological activities of the compounds that were present at sufficient levels for identification, benzyl acetate, hexanyl acetate, (Z)-3-hexenyl acetate, (Z)-3-octenyl acetate, octanyl acetate, (Z)-3-decenyl acetate, and (E)-β-farnesene, were evaluated at six different dosage levels by using electroantennography (EAG). Benzyl and hexanyl acetates elicited dose responses only in males, while other tested compounds elicited dose responses in both sexes. The strongest responses were observed for doses between 100 ng and 10 μg. The dose response, in terms of attractiveness to synthetic compounds within the active range (as determined by EAG), also was evaluated in the behavioral bioassay. Synthetic acetates were attractive to both sexes when tested individually. Significant attraction was observed when individual compounds were applied in the bioassay arena at doses of 0.5–1 μg/dispenser. Blends of compounds in equal proportions also were attractive to the insects. The most attractive blend was a mixture of four or five identified acetates. The addition of an equal proportion of (E)-β-farnesene to this mixture had a deterrent effect.  相似文献   
22.
Two clinical interventions to moderate negative responses to media exposure to terrorism were tested. Participants were 300 young Israeli adults randomly allocated to a terrorism or nonterrorism televised news clip and assigned to 1 of 3 preexposure intervention conditions--cognitive, emotional, or control. Emotional responses of anxiety and anger and attitudinal responses of stereotypes and enemy perception were measured prior and subsequent to manipulation. Results indicated higher posttest levels of anxiety, anger, stereotypes, and negative enemy perception in the terrorism versus nonterrorism media exposure. In the terrorism group, clinical interventions moderated anxiety and increased willingness for conflict resolution. Findings indicate contributions of preparatory interventions for the public in certain contexts of terrorism and its media coverage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
23.
This study addressed the issue of team support and explored the role of structural factors, namely, job enrichment designs; the role of cultural factors, namely, individualism-collectivism and power distance; and the role of the leader's support, which served as support carrier in teams. With 56 nursing teams, the results demonstrated that whereas leader's support, collectivism, and low power distance facilitated team support, job enrichment designs placed constraints on the accessibility of support to team members. Additionally, leader's support and low power distance moderated the negative impact of job enrichment on team support. These findings suggest that support is not primarily a burst of altruism displayed by individuals, and they draw attention to the teams' contexts that most likely serve to encourage team members to engage in support. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
24.
Transient gratings with R>96% at 1526 nm have been observed in Er3+/Yb3+-doped phosphosilicate optical fibres holographically processed with 193 nm light. These arise primarily from the index change associated with population inversion of the Er3+ ions  相似文献   
25.
The purpose of this study was to determine if normal participants and a patient with prosopanomia can be perceptually primed for proper names. To this end, 2 experiments were conducted. In Experiment 1, normative data were collected on 4 proper-name priming tasks. The variables of levels of processing at encoding and age were manipulated. Robust priming results were obtained that were not influenced by either of these variables. The results of Experiment 2 indicated that prosopanomic patient, N.G., demonstrated normal repetition priming, despite her marked impairment in deliberate retrieval of person and city names. These results are interpreted in terms of a dissociation between explicit and implicit memory for proper names and suggest that the deficit in prosopanomia only involves deliberate access to the name; access to presemantic representations of the visual word form remains intact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
26.
27.
以宁德市寿宁县坪坑大桥拱桥缆索吊装施工过程监控为例,基于现场实测数据,利用桥梁分析软件Midas对施工过程监控进行仿真分析,重点探讨拱圈拱箱节段吊装合龙、桥面铺装完成及徐变10年后的计算分析结果,得出施工预拱度的合理建议值及正常使用极限状态的计算结论,成果将为保证拱桥成桥线形提供理论依据及更好地指导后续施工。  相似文献   
28.
Chlorine isotope analysis of chlorinated hydrocarbons like trichloroethylene (TCE) is of emerging demand because these species are important environmental pollutants. Continuous flow analysis of noncombusted TCE molecules, either by gas chromatography/isotope ratio mass spectrometry (GC/IRMS) or by GC/quadrupole mass spectrometry (GC/qMS), was recently brought forward as innovative analytical solution. Despite early implementations, a benchmark for routine applications has been missing. This study systematically compared the performance of GC/qMS versus GC/IRMS in six laboratories involving eight different instruments (GC/IRMS, Isoprime and Thermo MAT-253; GC/qMS, Agilent 5973N, two Agilent 5975C, two Thermo DSQII, and one Thermo DSQI). Calibrations of (37)Cl/(35)Cl instrument data against the international SMOC scale (Standard Mean Ocean Chloride) deviated between instruments and over time. Therefore, at least two calibration standards are required to obtain true differences between samples. Amount dependency of δ(37)Cl was pronounced for some instruments, but could be eliminated by corrections, or by adjusting amplitudes of standards and samples. Precision decreased in the order GC/IRMS (1σ ≈ 0.1‰), to GC/qMS (1σ ≈ 0.2-0.5‰ for Agilent GC/qMS and 1σ ≈ 0.2-0.9‰ for Thermo GC/qMS). Nonetheless, δ(37)Cl values between laboratories showed good agreement when the same external standards were used. These results lend confidence to the methods and may serve as a benchmark for future applications.  相似文献   
29.
PURPOSE: The 2 types of urethral injury that can occur during circumcision are urethrocutaneous fistula and urethral distortion secondary to partial glans amputation. We report the surgical repair of these rare injuries. MATERIALS AND METHODS: In 8 patients urethrocutaneous fistulas located on the distal penile shaft or at the coronal margin were managed by splitting the glans and using a Mathieu style skin flap in 4 or vascularized penile skin flap in 4 to bridge the urethral defect. Three patients underwent repair of a hypospadiac deviated urethra secondary to partial glans amputation by 1 cm. of urethral mobilization and repositioning the meatus into a terminal position within the remaining glans tissue. RESULTS: The 8 patients with urethrocutaneous fistulas voided via a terminal meatus without fistula recurrence at a mean followup of 3.2 years (range 1 to 6). The 3 patients with partial glans amputation and urethral deviation repaired by short urethral advancement had functionally acceptable results, defined as a normal urinary stream, although 1 required meatal dilation postoperatively. CONCLUSIONS: The 2 types of urethral injuries that can occur during circumcision are a subcoronal urethrocutaneous fistula and scarred abnormal urethra from partial glans amputation. The urethrocutaneous fistula can be successfully repaired by splitting the glans and forming a neourethra from a vascularized pedicle flap of penile skin. The abnormal urethra after partial glans amputation is more difficult to repair but repositioning the urethra in a more cosmetic location has restored function.  相似文献   
30.
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