全文获取类型
收费全文 | 364篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 64篇 |
金属工艺 | 8篇 |
机械仪表 | 2篇 |
建筑科学 | 10篇 |
能源动力 | 5篇 |
轻工业 | 30篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 32篇 |
一般工业技术 | 52篇 |
冶金工业 | 47篇 |
原子能技术 | 1篇 |
自动化技术 | 114篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 3篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 18篇 |
2011年 | 36篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 25篇 |
2007年 | 12篇 |
2006年 | 19篇 |
2005年 | 9篇 |
2004年 | 12篇 |
2003年 | 8篇 |
2002年 | 7篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1977年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有371条查询结果,搜索用时 15 毫秒
51.
Prosocial behavior is important for the functioning of society. This study investigates the extent to which environment shared by family members, nonshared environment, and genetics account for children's prosocial behavior. The prosocial behavior of twins (9,424 pairs) was rated by their parents at the ages of 2, 3, 4, and 7 and by their teachers at age 7. For parent ratings, shared environmental effects decreased from .47 on average at age 2 to .03 at age 7, and genetic effects increased from .32 on average to .61. The finding of weak shared environmental effects and large heritability at age 7 was largely confirmed through the use of teacher ratings. Using longitudinal genetic analyses, the authors conclude that genetic effects account for both change and continuity in prosocial behavior and nonshared environment contributes mainly to change. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
52.
Golden Charles J.; Ariel Rona Notestine; McKay Stephen E.; Wilkening Greta N.; Wolf Brian A.; MacInnes William D. 《Canadian Metallurgical Quarterly》1982,50(2):291
Since the introduction of the Luria-Nebraska Neuropsychological Battery (LNNB), issues related to its understanding, interpretation, and validity have generated much interest. In response to P. A. Spiers's (see record 1981-24833-001) criticism of the battery, the authors suggest that the controversy appears to arise from a divergence in theoretical orientation on the role of quantitative versus qualitative assessment as well as from differences in the understanding of measurement methodology and validity. The present article discusses the theoretical basis from which the LNNB was constructed and describes the process of test interpretation. Previous and current research on use and validity of the battery is presented as it relates to the theoretical and methodological concerns. While basic philosophical differences with other theoretical systems are not likely to be resolved, the authors of the LNNB will continue to emphasize the integration of quantitative and qualitative approaches, both in the use of the LNNB and in the field of neuropsychology in general. It is concluded that the LNNB will continue to be revised on the basis of research findings and experience with the test in different patient populations. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
53.
A Ariel R Hershkoviz L Cahalon DE Williams SK Akiyama KM Yamada C Chen R Alon T Lapidot O Lider 《Canadian Metallurgical Quarterly》1997,27(10):2562-2570
The putative effects of interleukin (IL)-7, operating in the context of extracellular matrix (ECM), on the adhesion of human T cells were examined. Recombinant human, IL-7 was found to bind ECM or fibronectin (FN) with IC50 values of 10-100 nM. Nanogram amounts of both soluble and, especially, FN- or ECM-bound IL-7, which differentially affected the morphologies of FN-adherent T cells, induced the adhesion of resting CD4+ and CD8+ T cells in dose-dependent and beta 1 integrin-dependent manners. Under static and flow conditions, soluble IL-7 also induced the binding of unstimulated T cells to vascular cell adhesion molecule-1, suggesting that this cytokine can also modulate integrin binding to endothelial cell ligands. The effects of affinity modulation by IL-7 of FN-specific beta 1 integrins depend on the presence of soluble FN, which inhibited T cell adhesion to FN induced by FN-bound IL-7 or by an integrin-specific affinity-modulating monoclonal antibody, but not by soluble IL-7 or phorbol 12-myristate 13-acetate. These findings provide an example of a major ECM integrin ligand, FN, which is capable of modulating its adhesive interactions with specific immune cells by associating with and presenting a cytokine in a bio-active state. 相似文献
54.
55.
Optical encoders are used in industrial and laboratory motion equipment to measure rotations and linear displacements. We introduce a design of an optical encoder based on a nondiffractive beam. We expect that the invariant profile and radial symmetry of the nondiffractive beam provide the design with remarkable tolerance to mechanical perturbations. We experimentally demonstrate that the proposed design generates a suitable output sinusoidal signal with low harmonic distortion. Moreover, we present a numerical model of the system based on the angular spectrum approximation whose predictions are in excellent agreement with the experimental results. 相似文献
56.
Morgan JL Gordon GW Arrua RC Skulan JL Anbar AD Bullen TD 《Analytical chemistry》2011,83(18):6956-6962
We describe a new chemical separation method to isolate Ca from other matrix elements in biological samples, developed with the long-term goal of making high-precision measurement of natural stable Ca isotope variations a clinically applicable tool to assess bone mineral balance. A new two-column procedure utilizing HBr achieves the purity required to accurately and precisely measure two Ca isotope ratios ((44)Ca/(42)Ca and (44)Ca/(43)Ca) on a Neptune multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS) in urine. Purification requirements for Sr, Ti, and K (Ca/Sr > 10?000; Ca/Ti > 10?000?000; and Ca/K > 10) were determined by addition of these elements to Ca standards of known isotopic composition. Accuracy was determined by (1) comparing Ca isotope results for samples and standards to published data obtained using thermal ionization mass spectrometry (TIMS), (2) adding a Ca standard of known isotopic composition to a urine sample purified of Ca, and (3) analyzing mixtures of urine samples and standards in varying proportions. The accuracy and precision of δ(44/42)Ca measurements of purified samples containing 25 μg of Ca can be determined with typical errors less than ±0.2‰ (2σ). 相似文献
57.
Susane Moreira Machado Anderson Oliveira Lobo Ariel Bueno Loureiro Sapucahy Fernanda Roberta Marciano Evaldo Jose Corat Newton Soares da Silva 《Materials science & engineering. C, Materials for biological applications》2011,31(7):1614-1617
For the first time, we show that Tritrichomonas foetus can adhere on superhydrophilic vertically aligned carbon nanotubes (VACNT) films. Scanning electron microscopy shows an unusual adhesion with a higher membrane filopodium projection in all directions, directly attached to superhydrophilic VACNT tips. 相似文献
58.
The absorption and the kinetics of the emission in the mid-infrared (mid-IR) were investigated in AgCl(x)Br(1-x) crystals doped with Dy(3+) ions. Strong emission bands were detected at 3, 4.4, and 5.5 μm and attributed to the (6)H(13/2)→(6)H(15/2), (6)H(11/2)→(6)H(13/2), and (6)F(11/2)+(6)H(9/2)→(6)H(11/2) transitions. Various optical parameters were calculated for the Dy(3+) doped crystals, using the Judd-Ofelt approximation and the rate equations. The measured results and the calculated parameters indicate that these doped crystals could be used for the development of mid-IR solid-state lasers or mid-IR fiber lasers. 相似文献
59.
Prof. Dr. P. D. Ariel 《Acta Mechanica》1994,107(1-4):199-204
Summary The flow of a second order viscoelastic fluid past a porous plate is considered. It is characterized by a boundary value problem in which the order of the differential equation exceeds the number of available boundary conditions. The boundary value problem is solved by making a plausible assumption, namely that the variation of the normal derivative of the velocity at the plate withk is sufficiently smooth, wherek is the viscoelastic fluid parameter. Under this assumption it is shown that dual solutions exist for values ofk less than a critical value. Beyond this value, no solution exists. 相似文献
60.
De Cremer David; Brockner Joel; Fishman Ariel; van Dijke Marius; van Olffen Woody; Mayer David M. 《Canadian Metallurgical Quarterly》2010,95(2):291
Prior research has shown that procedural fairness interacts with outcome fairness to influence employees’ work attitudes (e.g., organizational commitment) and behaviors (e.g., job performance, organizational citizenship behavior), such that employees’ tendencies to respond more positively to higher procedural fairness are stronger when outcome fairness is relatively low. In the present studies, we posited that people’s uncertainty about their standing as organizational members would have a moderating influence on this interactive relationship between procedural fairness and outcome fairness, in that the interactive relationship was expected to be more pronounced when uncertainty was high. Using different operationalizations of uncertainty of standing (i.e., length of tenure as a proxy, along with self-reports and coworkers’ reports), we found support for this hypothesis in 4 field studies spanning 3 different countries. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献