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   174篇
  免费   4篇
电工技术   1篇
化学工业   15篇
金属工艺   2篇
机械仪表   2篇
建筑科学   14篇
能源动力   1篇
轻工业   17篇
无线电   10篇
一般工业技术   9篇
冶金工业   89篇
自动化技术   18篇
  2024年   1篇
  2022年   1篇
  2021年   3篇
  2020年   4篇
  2019年   3篇
  2018年   3篇
  2017年   1篇
  2016年   6篇
  2013年   4篇
  2012年   3篇
  2011年   8篇
  2010年   15篇
  2009年   5篇
  2008年   5篇
  2007年   4篇
  2006年   3篇
  2005年   3篇
  2004年   8篇
  2003年   5篇
  2002年   4篇
  2001年   2篇
  2000年   5篇
  1999年   2篇
  1998年   20篇
  1997年   9篇
  1996年   10篇
  1995年   5篇
  1994年   2篇
  1993年   6篇
  1992年   5篇
  1991年   1篇
  1990年   1篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1983年   2篇
  1982年   3篇
  1981年   1篇
  1980年   1篇
  1979年   2篇
  1976年   2篇
  1972年   1篇
  1966年   2篇
排序方式: 共有178条查询结果,搜索用时 10 毫秒
21.
28 adults and 48 8-mo-old infants listened to repeated transpositions of a 10-note melody exemplifying the rules of Western tonal music. They were tested for their detection of 2 types of changes to that melody: (1) a 4-semitone change in 1 note that remained within the key and implied dominant harmony (diatonic change) or (2) a 1-semitone change in the same note that went outside the key (nondiatonic change). Adults easily detected the nondiatonic change but had difficulty with the diatonic change. Infants detected both changes equally well, performing better than adults in some circumstances. These findings imply that there are qualitative differences in infants' and adults' processing of musical information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
Tested the claim of R. L. Archer et al (see record 1982-05783-001) that empathy leads to increased helping only under socially evaluative circumstances. In Exp I, 22 female undergraduates were led to believe that no one (including the person in need) would ever know if they declined to help. In this situation, which was designed to be devoid of the potential for negative social evaluation for not helping, there was still a positive relationship between self-reported empathic emotion and offering help. In Exp II, empathy (low vs high) and social evaluation (low vs high) were manipulated with 32 Ss. Once again there was a positive relationship between empathy and offering help when the potential for social evaluation was low as well as high. Results of both studies suggest that the motivation to help evoked by empathy is not egoistic motivation to avoid negative social evaluation. Instead, the observed pattern was what would be expected if empathy evokes altruistic motivation to reduce the victim's need. (23 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
23.
We describe an instrument to record x-ray diffraction patterns from diseased regions of human brain tissue by combining an in-line visible light fluorescence microscope with an x-ray diffraction microprobe. We use thiazine red fluorescence to specifically label and detect the filamentous tau protein pathology associated with Pick's disease, as several labs have done previously. We demonstrate that thiazine red-enhanced regions within the tissue show periodic structure in x-ray diffraction that is not observed in healthy tissue. One observed periodicity (4.2 ?) is characteristic of cross-beta sheet structure, consistent with previous results from powder diffraction studies performed on purified, dried tau protein.  相似文献   
24.
BACKGROUND: The dysregulation of both myc gene expression and retinoid signaling pathways commonly occurs in small cell lung carcinoma (SCLC). Because preclinical data showed that all-trans-retinoic acid (RA) inhibited SCLC growth, altered myc expression, and blocked transition to a treatment-resistant phenotype, a Phase II trial was designed to determine the effects of the combination of RA, cisplatin, and etoposide in patients with SCLC. METHODS: Patients with untreated, extensive stage SCLC were treated with up to 8 cycles of cisplatin, 60 mg/m2, intravenously (i.v.) on Day 1 and etoposide, 120 mg/m2, i.v. on Days 1-3 in addition to up to 1 year of oral RA, 150 mg/m2/day. RESULTS: Of 22 assessable patients 1 had a complete response and 9 had a partial response, for an overall response rate of 45% (95% confidence interval, 24-68%). The median survival was 10.9 months and the 1-year survival was 41%. The median duration of chemotherapy was 6 cycles and the median duration of RA treatment was 2.8 months. Thirteen patients discontinued RA prematurely due to toxicity and only 4 responders were receiving RA at the time of recurrence. Toxicity-limiting RA treatment mainly was comprised of mucocutaneous changes and headaches. CONCLUSIONS: RA at a dose of 150 mg/m2/day was tolerated poorly in combination with cisplatin plus etoposide, leading to early discontinuation of RA in the majority of patients. The hematologic toxicity, response rate, and survival were similar to those associated with cisplatin and etoposide in prior trials. Further studies with more active and less toxic agents will be required to determine the role of retinoids in the treatment of SCLC.  相似文献   
25.
OBJECTIVE: The purpose of this study was to determine whether emboli can be detected within the aortic lumen in patients undergoing coronary artery bypass surgery (CABG) and to relate the appearance of emboli to specific operative events. DESIGN: Twenty patients were prospectively studied intra-operatively. SETTING: Subjects were inpatients in an academic medical center. PARTICIPANTS: All participants were scheduled for elective, isolated CABG. INTERVENTIONS: Patients were continuously monitored using transesophageal echocardiography (TEE) from aortic cannulation to bypass discontinuation. After completion of the aortic examination, the probe was focused at the level of the aortic arch, just before the takeoff of the left subclavian artery. Emboli were defined as echogenic intraluminal signals not present in the same position on consecutive cross-sectional frames. RESULTS: Intraluminal emboli were detected in all subjects, with a mean number of 535 and range of 8 to 1,885. Embolization was unevenly distributed through the procedure. A mean of 224 (42%) of 535 were detected within 4 minutes of aortic cross-clamp release and another 140 (24%) appeared after partial occlusion clamp release. Together, clamp placement and release represented 84% of all emboli. Emboli detected after clamp release were large, echodense particles easily distinguishable from the small, indistinct, poorly echogenic signals observed at bypass initiation. CONCLUSIONS: Emboli can be visualized within the aortic lumen during CABG. Confirming previous reports, the majority of emboli detected are related to manipulation of aortic clamps. The composition and clinical significance of embolic material are unclear. The value of intraoperative TEE monitoring in predicting neurologic outcome remains to be determined.  相似文献   
26.
It is well documented that IL-6 plays a critical role in B cell terminal differentiation, and in mucosal sites it stimulates proliferation and large-scale secretion of immunoglobulin by B cells, especially those committed to IgA production. The close juxtaposition of IL-6 mRNA+ cells to plasma cells in the intestinal lamina propria supports the proposition that IL-6 production in situ is an important factor determining the outcome of antibody responses at that site. However, it has not been established previously whether exogenous IL-6 could boost antibody responses in the intestine if administered with a challenge antigen. Using a resected gut loop (Thiry-Vella loop) model, we have been able to demonstrate that in mice with double loops, antibody containing cell responses to lumenal administration of ovalbumin were 50% greater in loops given intralumenal recombinant IL-6 with the challenge antigen, than in loops challenged with antigen alone. This demonstrates the efficacy of IL-6 in promoting accumulation of antibody secreting cells in the gut, and suggests a potential therapeutic role for IL-6 to enhance responses to mucosal vaccines.  相似文献   
27.
The simulated extended pedigree data of the Genetic Analysis Workshop 10 were used to examine the relationship between several quantitative traits (Q1-Q5), an environmental factor, age and sex and to identify genes contributing to the quantitative traits. A forward selection procedure was used to identify regression models for each trait. Residuals from these regression models were used as quantitative traits in linkage analysis. Two-point sib-pair analysis was performed on Replicate 1 of the data set using SIBPAL. Sixteen regions on 8 chromosomes yielded two-point p-values < 0.005 in Replicate 1. Two strategies for utilizing a second data set were evaluated. In a two-stage approach, only those regions with p-value < 0.005 in Replicate 1 were followed up in the second data set. Nine of these regions had p-values < 0.05 in Replicate 2; four were associated with major genes included in the generating model and the remaining five regions were false positives. An alternative strategy was to perform a repeat genome wide screen in the second data set. This strategy resulted in the identification of 20 regions with p-values < 0.05 in both replicates; five of which included major genes included in the generating model. Although the false positive rate increased when a complete genome screen was performed on both data sets, the two-stage screen, with a more stringent initial criterion for identifying suggestive linkages, had a higher rate of false negatives. For some studies, conducting two complete genome screens in a split-sample design may be worthwhile.  相似文献   
28.
Prior studies assessing the relation between negative affective traits and cortisol have yielded inconsistent results. Two studies assessed the relation between individual differences in repressive-defensiveness and basal salivary cortisol levels. Experiment I assessed midafternoon salivary cortisol levels in men classified as repressors, high-anxious, or low-anxious. In Experiment 2, more rigorous controls were applied as salivary cortisol levels in women and men were assessed at 3 times of day on 3 separate days. In both studies, as hypothesized, repressors and high-anxious participants demonstrated higher basal cortisol levels than low-anxious participants. These findings suggest that both heightened distress and the inhibition of distress may be independently linked to relative elevations in cortisol. Also discussed is the possible mediational role of individual differences in responsivity to, or mobilization for, uncertainty or change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
29.
Random effects models were used to examine the association between behavioral disturbances in persons with Alzheimer's disease (N = 90) and caregiver depressive symptoms at 2-month intervals over an 18-month period. There was substantial variability in trajectories of change in caregiver depressive symptoms over time but no systematic increase in distress despite increased severity of dementia symptoms. Total behavioral disturbances were associated with higher levels of caregiver depressive symptoms: this effect was primarily attributable to aggressive behaviors. No consistent departure from linearity was evident in the relationship between behavior and depression over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
30.
This paper presents a comparison of two- finite-element programs developed for accurate cross-sectional analysis of arbitrary optical and microwave waveguiding structures. Both techniques were developed in response to the growing demand from scientists and engineers for application-specific expert systems, and employ advanced interactive pre- and post-processing facilities. They show good agreement, strongly complement one another, and could form the core of a whole library of similar “intelligent” software for computer-assisted analysis and design, with a wide range of possible applications within both supercomputer and workstation environments  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