全文获取类型
收费全文 | 3628篇 |
免费 | 235篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 740篇 |
金属工艺 | 16篇 |
机械仪表 | 30篇 |
建筑科学 | 150篇 |
矿业工程 | 4篇 |
能源动力 | 56篇 |
轻工业 | 443篇 |
水利工程 | 45篇 |
石油天然气 | 8篇 |
无线电 | 183篇 |
一般工业技术 | 597篇 |
冶金工业 | 1203篇 |
原子能技术 | 1篇 |
自动化技术 | 372篇 |
出版年
2024年 | 8篇 |
2023年 | 26篇 |
2022年 | 61篇 |
2021年 | 98篇 |
2020年 | 64篇 |
2019年 | 59篇 |
2018年 | 89篇 |
2017年 | 89篇 |
2016年 | 91篇 |
2015年 | 96篇 |
2014年 | 114篇 |
2013年 | 208篇 |
2012年 | 184篇 |
2011年 | 328篇 |
2010年 | 243篇 |
2009年 | 213篇 |
2008年 | 267篇 |
2007年 | 242篇 |
2006年 | 207篇 |
2005年 | 174篇 |
2004年 | 137篇 |
2003年 | 124篇 |
2002年 | 120篇 |
2001年 | 81篇 |
2000年 | 72篇 |
1999年 | 63篇 |
1998年 | 41篇 |
1997年 | 61篇 |
1996年 | 43篇 |
1995年 | 42篇 |
1994年 | 29篇 |
1993年 | 29篇 |
1992年 | 20篇 |
1991年 | 7篇 |
1990年 | 19篇 |
1989年 | 22篇 |
1988年 | 12篇 |
1987年 | 14篇 |
1986年 | 11篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 5篇 |
1972年 | 1篇 |
排序方式: 共有3865条查询结果,搜索用时 15 毫秒
31.
Jennifer Colegrove 《中国电子商情》2008,(7)
iSuppli公司预测,在苹果公司iPhone热销及其精致的用户接口刺激下,2008-2012年全球触摸屏显示器模块出货量将增长一倍以上。 相似文献
32.
Rowan Paul J.; Cofta-Woerpel Ludmila; Mazas Carlos A.; Vidrine Jennifer Irvin; Reitzel Lorraine R.; Cinciripini Paul M.; Wetter David W. 《Canadian Metallurgical Quarterly》2007,15(4):382
Ecological momentary assessment (EMA) consists of assessing phenomena in real time in the natural environment. EMA allows for more fine-grained analyses of addictive behavior and minimizes threats to internal validity, such as recall biases and errors. However, because of the intensive monitoring involved in EMA, measurement reactivity is a concern. To test whether EMA with palmtop personal computers induces reactivity, the authors compared smoking-related outcomes between smokers using EMA and those not using EMA during a quit attempt. The use of no-EMA control groups has been rare in reactivity investigations to date. The EMA protocol included event-contingent assessments (smoking episodes, urge episodes) and random assessments. Outcomes included biologically confirmed abstinence and self-report measures of withdrawal, self-efficacy, motivation, affect, and temptations. Participants were smokers motivated to quit (N = 96). They were randomized to 1 of 3 groups: EMA for the week preceding a planned quit date, EMA for the week following the quit date, and no EMA. Abstinence rates did not differ between the groups at Day 7 or at Day 28 postcessation. For the 20 subscales assessed at each of 3 assessment times, there were significant differences between participants with and without EMA experience for 3 subscales at the 1st of 3 assessment times, and significant differences for 3 different subscales at the 3rd assessment time. These differences suggest some reactivity to EMA, although the inconsistent pattern across time indicates that further research is needed to definitively conclude that EMA induces reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
Miller Mark W.; Greif Jennifer L.; Smith Alethea A. 《Canadian Metallurgical Quarterly》2003,15(2):205
This study used the Multidimensional Personality Questionnaire (MPQ; A. Tellegen, in press) to identify personality-based subtypes of posttraumatic response. Cluster analyses of MPQs completed by combat veterans revealed subgroups that differed on measures relating to the externalization versus internalization of distress. The MPQ profile of the externalizing cluster was defined by low Constraint and Harmavoidance coupled with high Alienation and Aggression. Individuals in this cluster also had histories of delinquency and high rates of substance-related disorder. In comparison, the MPQ profile of the internalizing cluster was characterized by lower Positive Emotionality, Alienation, and Aggression and higher Constraint, and individuals in this cluster showed high rates of depressive disorder. These findings suggest that dispositions toward externalizing versus internalizing psychopathology may account for heterogeneity in the expression of posttraumatic responses, including patterns of comorbidity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
34.
35.
Jennifer K. Edwards Adrian Thomas Benjamin E. Solsona Philip Landon Albert F. Carley Graham J. Hutchings 《Catalysis Today》2007,122(3-4):397-402
The direct synthesis of hydrogen peroxide from H2 and O2 using a range of supported Au–Pd alloy catalysts is compared for different supports using conditions previously identified as being optimal for hydrogen peroxide synthesis, i.e. low temperature (2 °C) using a water–methanol solvent mixture and short reaction time. Five supports are compared and contrasted, namely Al2O3, -Fe2O3, TiO2, SiO2 and carbon. For all catalysts the addition of Pd to the Au only catalyst increases the rate of hydrogen peroxide synthesis as well as the concentration of hydrogen peroxide formed. Of the materials evaluated, the carbon-supported Au–Pd alloy catalysts give the highest reactivity. The results show that the support can have an important influence on the synthesis of hydrogen peroxide from the direct reaction. The effect of the methanol–water solvent is studied in detail for the 2.5 wt% Au–2.5 wt% Pd/TiO2 catalyst and the ratio of methanol to water is found to have a major effect on the rate of hydrogen peroxide synthesis. The optimum mixture for this solvent system is 80 vol.% methanol with 20 vol.% water. However, the use of water alone is still effective albeit at a decreased rate. The effect of catalyst mass was therefore also investigated for the water and water–methanol solvents and the observed effect on the hydrogen peroxide productivity using water as a solvent is not considered to be due to mass transfer limitations. These results are of importance with respect to the industrial application of these Au–Pd catalysts. 相似文献
36.
In recent years, both functionalist and dynamic systems approaches have assumed increasing prominence in the study of emotion and its development, but the similarities and differences between these perspectives remain largely unexplored and open to more systematic examination. In this article, the authors argue that both approaches share a systems view of emotion and regard emotion in relational, process terms. However, each approach adopts a distinct level of analysis and distinct types of explanation for emotion and its development. Whereas the functionalist approach appeals to formal and final causes to explain patterning in emotion at the level of organism-environment relations, the dynamic systems approach appeals to efficient and material causes to explain emotion at the specific content level of behavior in context. Whether these approaches complement or conflict with one another depends on the extent to which the dynamic systems approach admits abstraction into its explanatory framework. A. Fogel's social process theory and M. D. Lewis' approach to emotion self-organization are discussed in this regard. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
38.
Rheological Property and Stress Development during Drying of Tape-Cast Ceramic Layers 总被引:1,自引:0,他引:1
Jennifer A. Lewis Kimberly A. Blackman rea L. Ogden James A. Payne Lorraine F. Francis 《Journal of the American Ceramic Society》1996,79(12):3225-3234
Rheological property and stress development of tape-cast ceramic layers derived from nonaqueous alumina (A12 O3 )-poly(vinyl butyral) (PVB) suspensions were observed during drying. Casting suspensions exhibited strong shear-thinning behavior, with a low shear Newtonian plateau apparent viscosity >102 Pa. s. The apparent suspension viscosity displayed a power-law dependence on the A12 O3 volume fraction during the initial stage of drying (<30% solvent loss). Stress development, measured by a cantilever deflection method, and parallel weight loss measurements were performed during the drying of tape-cast layers and pure binder coatings. Maximum drying stresses (σmax ) of 1.37-0.77 MPa were observed for plasticized tapes cast at gap heights of 150-400 μm. In contrast, nonplasticized tapes of similar thickness displayed a more gradual stress increase, with σmax values approximately an order of magnitude higher than their plasticized counterparts. The stress histories of the corresponding binder coatings were quite similar to the tape-cast layers, albeit slightly lower σ max values were observed. Stresses decayed beyond σmax with a logarithmic time dependence to an almost constant value of 0.2-0.4 MPa for the plasticized tapes. Based on these observations, process methodologies have been offered to minimize stress development and retention in tape-cast ceramic layers 相似文献
39.
VC Dias KL Madsen KE Mulder M Keelan RW Yatscoff AB Thomson 《Canadian Metallurgical Quarterly》1998,43(10):2227-2236
The immunosuppressive drugs rapamycin (Rap) and cyclosporine A (CsA) are used clinically to modify or abolish immune-mediated functions. This study examined the effect of orally administered regimens of Rap, CsA, and a combination of Rap/CsA on intestinal function in male New Zealand white rabbits. Animals received oral doses of CsA (15 mg/kg/body weight/day), low-dose (LD) and high-dose (HD) Rap (0.25 or 1 mg/kg/body wt/day, respectively), or Rap/CsA (0.25 and 5 mg/kg/body wt/day, or 0.5 and 5 mg/kg/body wt/day, respectively) for 20 days. We measured in vitro uptake of nutrients and permeability, and morphometric measurements in the jejunum and ileum were made. Animals receiving HD-Rap or HD-Rap/CsA had decreased food intake, body weight, and intestinal weight, when compared with LD-Rap, LD-Rap/CsA, CsA, or controls. The maximal transport rate (Vmax) for the active jejunal uptake of D-glucose was increased in HD-Rap and CsA, but not in the HD-Rap/CsA-treated animals. The jejunal Vmax of D-glucose in the LD-Rap- or -Rap/CsA-treated animals was no different from controls. In the HD-Rap- and HD-Rap/ CsA-treated animals, jejunal rates of uptake of stearic, linoleic, and linolenic acids were reduced when compared with controls. Jejunal and ileal permeability (as assessed by the passive uptake of L-glucose, tissue conductance, and mucosal-to-serosal flux of [3H]inulin) was increased in animals treated with HD-Rap or HD-Rap/CsA, when compared with CsA or controls. These parameters of permeability were no different at lower doses of Rap or Rap/CsA. The jejunal and ileal villous surface area was increased in CsA, but decreased in HD-Rap or HD-Rap/CsA animals. Thus, HD-Rap given alone or in combination with CsA reduced body weight gain, in part due to reduced food intake and malabsorption of lipids, which was due at least in part to reduced intestinal surface area. The relevance of these findings to patients undergoing chronic immunosuppressive drug therapy needs to be established. 相似文献
40.
Daun Marian Brings Jennifer Krajinski Lisa Stenkova Viktoria Bandyszak Torsten 《Requirements Engineering》2021,26(3):325-370
Requirements Engineering - Collaborative cyber-physical systems are capable of forming networks at runtime to achieve goals that are unachievable for individual systems. They do so by connecting to... 相似文献