全文获取类型
收费全文 | 636篇 |
免费 | 25篇 |
专业分类
电工技术 | 2篇 |
综合类 | 1篇 |
化学工业 | 110篇 |
金属工艺 | 14篇 |
机械仪表 | 6篇 |
建筑科学 | 21篇 |
能源动力 | 30篇 |
轻工业 | 35篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 51篇 |
一般工业技术 | 100篇 |
冶金工业 | 217篇 |
原子能技术 | 2篇 |
自动化技术 | 68篇 |
出版年
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 7篇 |
2016年 | 13篇 |
2015年 | 11篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 22篇 |
2011年 | 22篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 22篇 |
2007年 | 19篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 14篇 |
2003年 | 21篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 42篇 |
1997年 | 38篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 19篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 9篇 |
1976年 | 12篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1970年 | 4篇 |
排序方式: 共有661条查询结果,搜索用时 46 毫秒
1.
Alberto Ballesteros Ester Laguna-Gutierrez Paula Cimavilla-Roman Maria Luisa Puertas Antonio Esteban-Cubillo Julio Santaren Miguel Angel Rodriguez-Perez 《应用聚合物科学杂志》2021,138(46):51373
In the present work blends of polystyrene (PS) with sepiolites have been produced using a melt extrusion process. The dispersion degree of the sepiolites in the PS has been analyzed by dynamic shear rheology and X-ray micro-computed tomography. Sepiolites treated with quaternary ammonium salts (O-QASEP) are better dispersed in the PS matrix than natural sepiolites (N-SEP) or sepiolites organo-modified with silane groups (O-SGSEP). A percolated network is obtained when using 6.0 wt% of O-QASEP, 8.0 wt% of N-SEP and 10.0 wt% of O-SGSEP. It has been shown that multiple extrusion processes have a negative effect on the polymer architecture. They produce a reduction in the length of the polymeric chains, and they do not lead to a better dispersion of the particles in the polymer matrix. Foams have been produced using a gas dissolution foaming process, where a strong effect of the dispersion degree on the cellular structure of the different foams was found. The effects on the cellular structure obtained by using different types of sepiolites, different contents of sepiolites and different extrusion conditions have been analyzed. The foams produced with the formulations containing O-QASEP present the lowest cell size and the most homogeneous cellular structures. 相似文献
2.
Carbon Black (CB)-containing immiscible polymer blends based on high-impact polystyrene/thermoplastic polyurethane (HIPS/TPU) were studied as sensing materials for an homologous series of alcohols, including, methanol, ethanol and 1-propanol. The studied immiscible blend was designed to exhibit a double-continuity structure i.e., the CB particles form chain-like network structures within the TPU phase, which forms a continuous phase within the HIPS matrix. Extruded HIPS/TPU/CB filaments produced by a capillary rheometer process at various shear rate levels were used for the sensing experiments. All filaments displayed a selective resistance changes upon exposure to the various alcohols combined with reproducibility and recovery behaviour. An attempt is made to identify the dominant mechanisms controlling the sensing process in a CB-containing immiscible polymer blend characterized by a double-continuity structure. The distinct structure and composition of the HIPS/TPU interphase region were found to have a crucial role in the sensing mechanism, determining the selectivity of the filaments toward the studied alcohols. Additionally, the sensing performance of HIPS/TPU/CB system is compared to recent results for TPU/CB compounds, polypropylene/TPU/CB and HIPS/ethylene vinyl acetate/CB immiscible polymer blends. 相似文献
3.
4.
Y Stern M Aronson T Shpitzer O Nativ O Medalia K Segal R Feinmesser 《Canadian Metallurgical Quarterly》1995,121(9):1003-1005
OBJECTIVE: To assess the role of DNA ploidy as a predictor of radioresistance in T1 glottic carcinoma. DESIGN: Case-control study. Flow cytometric DNA ploidy measurements were performed on formalin-fixed paraffin-embedded tumor specimens from 15 patients with T1 glottic laryngeal carcinomas in whom radiotherapy had failed and from a matched group of 15 patients in whom an identical radiotherapy regimen was curative. Analysis of DNA content was performed blind to outcome of treatment. SETTING: Academic tertiary referral medical center. PARTICIPANTS: Thirty patients with clinically staged T1, N0, M0 glottic carcinoma. INTERVENTION: All patients received radiation to the larynx through opposed lateral ports at a total dose of 64 to 70 Gy. RESULTS: Ten diploid and five aneuploid histograms were found in the resistant group, and six diploid and nine aneuploid histograms were found in the radiosensitive group. This difference was not statistically significant. A trend toward a higher relapse rate after radiotherapy (62.5%) among patients with diploid tumor compared with those with aneuploid tumor (35.7%) was noted. CONCLUSIONS: DNA ploidy did not predict response to radiotherapy in patients with T1 glottic cancer, probably because of the small number of patients. A trend toward lower risk of local recurrence after radiotherapy in aneuploid tumors was noted. A larger prospective study is needed to assess the value of DNA ploidy in the treatment of early laryngeal cancer. 相似文献
5.
Cu/Zn superoxide dismutase (Cu/Zn SOD) is a key enzyme in the metabolism of oxygen free radicals. The gene resides on chromosome 21 and is overexpressed in patients with Down syndrome. Cultured neurons of transgenic Cu/Zn SOD (Tg-Cu/Zn SOD) mice with elevated activity of Cu/Zn SOD were used to determine whether constitutive overexpression of Cu/Zn SOD creates an indigenous oxidative stress that predisposes the Tg-Cu/Zn SOD neurons to added insults. Neurons from three independently derived Tg-Cu/Zn SOD strains showed higher susceptibility than nontransgenic neurons to kainic acid (KA)-mediated excitotoxicity, reflected by an earlier onset and enhanced apoptotic cell death. This higher susceptibility of transgenic neurons to KA-mediated apoptosis was associated with a chronic prooxidant state that was manifested by reduced levels of cellular glutathione and altered [Ca2+]i homeostasis. The data are compatible with the thesis that overexpression of Cu/Zn SOD creates chronic oxidative stress in the transgenic neurons, which exacerbates their susceptibility to additional insults such as KA-mediated excitotoxicity. 相似文献
6.
Bouchard Thomas J.; Arvey Richard D.; Keller Lauren M.; Segal Nancy L. 《Canadian Metallurgical Quarterly》1992,77(1):89
Responds to the points made by R. Cropanzano and K. James (see record 1991-00462-001) concerning the article by R. D. Arvey et al (1989). The authors acknowledge that the Arvey et al study is based on a single design, makes use of a small and special sample, and, as such, is vulnerable to threats of internal and external validity. Nevertheless, after providing a more comprehensive conceptual and empirical context for the study, and after reviewing a number of the issues raised by Cropanzano and James, the authors conclude that it is not premature to accept the idea that work attitudes are partially genetically influenced. Indeed, the authors use behavioral genetic theory, together with data gathered in the Arvey et al study, to make specific point predictions regarding the outcomes of an array of studies that easily can be undertaken. Finally, the authors acknowledge that the comments and issues raised by Cropanzano and James, along with the interchange, can offer directions for future research in this important area. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
8.
Tellegen Auke; Lykken David T.; Bouchard Thomas J.; Wilcox Kimerly J.; Segal Nancy L.; Rich Stephen 《Canadian Metallurgical Quarterly》1988,54(6):1031
We administered the Multidimensional Personality Questionnaire (MPQ) to 217 monozygotic and 114 dizygotic reared-together adult twin pairs and 44 monozygotic reared-apart adult twin pairs. A four-parameter biometric model (incorporating genetic, additive versus nonadditive, shared family-environment, and unshared environment components) and five reduced models were fitted through maximum-likelihood techniques to data obtained with the 11 primary MPQ scales and its 3 higher order scales. Solely environmental models did not fit any of the scales. Although the other reduced models, including the simple additive model, did fit many of the scales, only the full model provided a satisfactory fit for all scales. Heritabilities estimated by the full model ranged from .39 to .58. Consistent with previous reports, but contrary to widely held beliefs, the overall contribution of a common family-environment component was small and negligible for all but 2 of the 14 personality measures. Evidence of significant nonadditive genetic effects, possibly emergenic (epistatic) in nature, was obtained for 3 of the measures. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
H Pawar EL Bingham K Hiriyanna M Segal JE Richards PA Sieving 《Canadian Metallurgical Quarterly》1996,46(6):329-335
We studied 17 pedigrees with 108 affected males with X-linked juvenile retinoschisis (RS; McKusick No. 31270) and have analyzed all of the known polymorphic markers in the RS region of Xp22.1-p22.2 between DXS987 and DXS41. By haplotype analyses we found 7 individuals who showed crossovers in this interval surrounding RS. We previously reported AFM291wf5 as the centromeric boundary, and this remains unchanged in the present study. A new recombination was identified on the telomeric side at (DXS1195, DXS418). Our data support the locus order Xpter--(DXS987, DXS207, DXS1053, DXS43)--(DXS1195, DXS418)--(RS, DXS257, DXS999)--(AFM291wf5, DXS443)--DXS1052--(DXS1226, DXS274, DXS41)--Xcen; loci grouped in parentheses could not be mutually ordered by our genetic data. Physical mapping has indicated a distance of at most 900-1,000 kb between (DXS1195, DXS418) and AFM291wf5. No recombination was observed between RS and DXS257 which lies in our new interval of interest, but one critical individual was not informative with this marker. Our data now define the smallest RS inclusion interval. This interval is contained on a single YAC from which we have identified expressed sequences as candidate genes for RS. 相似文献
10.
Proposes a more structured form of presupervisory preparation than generally exists in graduate training programs. Guidelines for incorporating such instruction are provided. Topics for discussion, including salient issues and perspectives in the supervision literature as well as research findings, are outlined. Potential pitfalls and strategies for trainees to deal with dissatisfactions are identified. The suggested curriculum for preparing the supervisee would cover the differences between a didactic and a therapeutic emphasis, stages of development within supervision, interpersonal relationships, and countertransference and parallel process. An overview of supervisory methods, especially with respect to the presentation of case material would also be valuable. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献