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   226篇
  免费   13篇
化学工业   54篇
机械仪表   1篇
建筑科学   11篇
能源动力   4篇
轻工业   30篇
水利工程   1篇
无线电   4篇
一般工业技术   38篇
冶金工业   66篇
自动化技术   30篇
  2024年   1篇
  2023年   2篇
  2022年   14篇
  2021年   15篇
  2020年   8篇
  2019年   9篇
  2018年   4篇
  2017年   6篇
  2016年   8篇
  2015年   10篇
  2014年   10篇
  2013年   13篇
  2012年   10篇
  2011年   20篇
  2010年   9篇
  2009年   9篇
  2008年   8篇
  2007年   14篇
  2006年   8篇
  2005年   5篇
  2004年   4篇
  2003年   3篇
  2002年   4篇
  2001年   1篇
  2000年   5篇
  1999年   2篇
  1998年   4篇
  1997年   2篇
  1996年   5篇
  1995年   3篇
  1993年   3篇
  1992年   2篇
  1990年   2篇
  1989年   2篇
  1988年   1篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
排序方式: 共有239条查询结果,搜索用时 15 毫秒
31.
This intervention study evaluates a decision-making aid for parents considering childhood immunizations. Participants (women in 3rd trimester of pregnancy, n = 100) rated likelihood of immunizing their child, anxiety, and perceptions of risk of the diseases and immunizations. Individuals were allocated to intervention group (received a decision aid) or control group (received standard care). Ratings were then repeated, and further ratings were obtained when the infant was 10 weeks old. The intervention compared with the comparison condition was associated with significant increase in likelihood of immunizing the infant on time, decreased perceptions of risks of immunizations, increased perceptions of risk of the diseases, reduced anxiety, and increased satisfaction. This intervention may form a useful basis for decision aids in health care settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
32.
Adult diaries and novels written by the British feminist and pacifist V. Brittain (1893–1970) were content analyzed for Eriksonian themes of identity, intimacy, and generativity. Brittain's concerns with identity and intimacy decreased over time, while her generative concerns increased, suggesting that she expressed the issue of generativity vs. stagnation in her mid-life diaries and fiction. The large number of identity themes relative to both intimacy and generativity provokes speculations about Brittain's personality, the characteristics of writers, the influence of gender, the impact of society, and the possibility that the crisis of identity vs. role confusion involves the last major structural change in personality development. This archival case study is consistent with Erikson's notion of a sequence of concerns with psychosocial issues, although directions for theoretical revision and elaboration are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
33.
Theories of adult development suggest that both personality and social roles are sources of adult well-being, but most research has examined only social roles. An integrated model was used, including personality, number of roles, and role quality, to predict well-being in 2 longitudinal studies of college-educated women. Results for both samples indicated that role quality and personality development were important components of the path to well-being, whereas number of roles occupied was important mainly in early adulthood. Moreover, the results provided support for E. Erikson's (1968) notion of the importance of the sequencing of personality development for later well-being. Path analyses indicated that engagement in multiple roles during early adulthood facilitated the development of identity, which predicted generativity and role quality, which in turn predicted well-being. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
34.
Administered a battery of 4 tests adapted from the structure of intellect model of differential abilities to 72 adults with right and left cerebral lesions and normals. Findings show that both brain-damaged groups exhibited slower response times than normals and that there was a relation between locus of the lesion and performance. However, results do not sufficiently demonstrate the advantage of factor-defined ability tests over tests of global intelligence and question the validity of these factor-defined tests in that they do not distinguish behaviors that are factorially distinct in normal populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
35.
Keratan sulfate (KS) is a glycosaminoglycan consisting of repeating disaccharide units composed of alternating residues of d-galactose and N-acetyl-d-glucosamine linked beta-(1-4) and beta-(1-3), respectively. In this study, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was employed to identify keratan sulfate oligosaccharides. Two nonsulfated disaccharide isomers and two monosulfated disaccharide isomers were distinguished through MS/MS. In MS(1) spectra of multiply sulfated KS oligosaccharides, the charge state of the most abundant molecular ion equals the number of sulfates. Subsequent MS(2) and MS(3) spectra of mono-, di-, tri-, and tetrasulfated KS oligosaccharides and sialylated tetrasaccharides reveal diagnostic ions that can be used as fingerprint maps to identify unknown KS oligosaccharides. Based on the pattern of fragment ions, the compositions of an oligosaccharide mixture from shark cartilage KS and of two enzyme digests of bovine corneal KS were determined directly, without prior isolation of individual oligosaccharides by HPLC or other methods.  相似文献   
36.
Five studies were conducted to test a general theory of adaptation or sequence of emotional stances to major life changes. Children entering school, middle-class students later in school, students in college, and women getting married and becoming mothers all seemed to renegotiate a similar sequence of concern with receptive issues, then with issues of autonomy and assertion, and finally with issues of integration. Exceptions to these results involved working-class students and new fathers. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
37.
This paper aims to evaluate part-load operation of a natural gas combined cycle (NGCC) power plant with exhaust gas recirculation (EGR) and a CO2 capture plant. Several studies have demonstrated the feasibility and the advantages of EGR at full load, but operation at part load is also important because it is a common condition when NGCC power plants are being used as backup for renewables. The results of this study show that the number of absorber trains is reduced from 4 to 3 with EGR. The efficiency of the NGCC plant with EGR was 0.5% points higher than a conventional NGCC at full load as a result of a higher CO2 concentration in the flue gas. However, this efficiency advantage decreased as the load was reduced from 100% to 50%, with both cases presenting the same efficiency at 50% load. This means that there was no benefit from the effect of EGR at lower loads. The efficiency of a NGCC plant with EGR and CO2 capture configuration decreased from 52.6% to 45.9% when the load was reduced from 100% to 50% compared with a conventional NGCC where the efficiency changed from 52.1% to 45.9%. It was concluded that a NGCC plant with EGR and CO2 capture is viable, results in lower capital costs due to the smaller number of absorber trains and yields slightly higher efficiencies, for operation at part-load down to 50%.  相似文献   
38.
The aim of this study was to investigate the in vitro acid-induced gelation of low acyl gellan gum. Various metabolically relevant pH environments and hydrocolloid concentrations were investigated. These resulted in very different acid structures, which were characterised by texture analysis, with Young’s and bulk moduli and work of failure being reported. The structures of the acid gels were shown to depend upon the pH and hydrocolloid concentration (c) used during their production, with a maximum in gel strength between pH 3 and 4. Both the Young’s and bulk moduli data suggest that there is a critical concentration for gelation to occur, and both parameter values displayed a gradual increase (which appears to be lower than a c2 dependency) as the gellan concentration was increased.  相似文献   
39.
Humans possess manual dexterity, motor skills, and other physical abilities that rely on feedback provided by the somatosensory system. Herein, a method is reported for creating soft somatosensitive actuators (SSAs) via embedded 3D printing, which are innervated with multiple conductive features that simultaneously enable haptic, proprioceptive, and thermoceptive sensing. This novel manufacturing approach enables the seamless integration of multiple ionically conductive and fluidic features within elastomeric matrices to produce SSAs with the desired bioinspired sensing and actuation capabilities. Each printed sensor is composed of an ionically conductive gel that exhibits both long‐term stability and hysteresis‐free performance. As an exemplar, multiple SSAs are combined into a soft robotic gripper that provides proprioceptive and haptic feedback via embedded curvature, inflation, and contact sensors, including deep and fine touch contact sensors. The multimaterial manufacturing platform enables complex sensing motifs to be easily integrated into soft actuating systems, which is a necessary step toward closed‐loop feedback control of soft robots, machines, and haptic devices.  相似文献   
40.
Nylon 6 and 6.6 fibers were submitted to thermal annealing in a wide range of temperatures (below and above their glass transition temperatures) under inert atmosphere and slack condition, allowing free shrinkage. The structural changes due to the heat settings were analyzed by several techniques (differential scanning calorimetry analysis, wide- and small-angle X-ray scattering, and birefringence). The results revealed different recrystallization responses of the fibers to the applied thermal annealings and consequently different shrinkage mechanisms. In the recrystallization of the Nylon 6 fibers were involved a generation of nuclei crystallites in the interfibrillar regions, as well as growth and perfection of these new crystallites and preexisting ones. But, recrystallization of the Nylon 6.6 fiber was accompanied only by growth and perfection of the preexisting crystals. The existence of the nuclei crystallites at temperatures of heat treatments above 120°C was the major commanding factor for the Nylon 6 fiber to undergo less shrinkage than the Nylon 6.6 fiber. These very tiny crystallites worked as crosslinking points that would impose restrictions in the mobility of the chains segments, inhibiting subsequent disorientation of the amorphous regions and consequently intense shrinkage, thus resulting in recrystallization in a preferred direction of the fiber axis. The Nylon 6.6 fiber experienced an instantaneous shrinkage at the annealing temperature around 70°C. That was the temperature necessary to release its hydrogen bonds and the starting temperature for presenting its major structural changes, including global disorientation of the amorphous and crystalline regions. Thus, its recrystallization occurred with no preferred orientation. Also, it was suggested that the occurrence of so different shrinkage mechanisms reside in the different crystalline morphology that these fibers originally possessed before the heat treatments. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 441–452, 1998  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