全文获取类型
收费全文 | 1202篇 |
免费 | 17篇 |
专业分类
电工技术 | 15篇 |
综合类 | 1篇 |
化学工业 | 213篇 |
金属工艺 | 30篇 |
机械仪表 | 47篇 |
建筑科学 | 35篇 |
矿业工程 | 7篇 |
能源动力 | 11篇 |
轻工业 | 137篇 |
水利工程 | 6篇 |
石油天然气 | 3篇 |
无线电 | 53篇 |
一般工业技术 | 193篇 |
冶金工业 | 382篇 |
原子能技术 | 8篇 |
自动化技术 | 78篇 |
出版年
2022年 | 9篇 |
2021年 | 12篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 12篇 |
2013年 | 38篇 |
2012年 | 33篇 |
2011年 | 46篇 |
2010年 | 32篇 |
2009年 | 23篇 |
2008年 | 30篇 |
2007年 | 41篇 |
2006年 | 38篇 |
2005年 | 32篇 |
2004年 | 20篇 |
2003年 | 25篇 |
2002年 | 26篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 36篇 |
1998年 | 85篇 |
1997年 | 47篇 |
1996年 | 40篇 |
1995年 | 31篇 |
1994年 | 27篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 18篇 |
1990年 | 13篇 |
1989年 | 20篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 20篇 |
1985年 | 21篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 20篇 |
1978年 | 22篇 |
1977年 | 22篇 |
1976年 | 31篇 |
1975年 | 18篇 |
1974年 | 14篇 |
1973年 | 11篇 |
1970年 | 11篇 |
1969年 | 10篇 |
排序方式: 共有1219条查询结果,搜索用时 15 毫秒
21.
Process optimization for efficient biomediated PHA production from animal-based waste streams 总被引:1,自引:1,他引:0
Michaela Titz Karl-Heinz Kettl Khurram Shahzad Martin Koller Hans Schnitzer Michael Narodoslawsky 《Clean Technologies and Environmental Policy》2012,14(3):495-503
Conventional polymers are made of crude oil components through chemical polymerization. The aim of the project ANIMPOL is to produce biopolymers by converting lipids into polyhydroxyalkanoates (PHA) in a novel process scheme to reduce dependence on crude oil and decrease greenhouse gas emissions. PHA constitutes a group of biobased and biodegradable polyesters that may substitute fossil-based polymers in a wide range of applications. Waste streams from slaughtering cattle are used as substrate material. Lipids from rendering are used in this process scheme for biodiesel production. Slaughtering waste streams may also be hydrolyzed to achieve higher lipid yield. Biodiesel then is separated into a high- and low-quality fraction. High-quality biodiesel meets requirements for sale as fuel and low quality is used for PHA production as carbon source. Selected offal material is used for acid hydrolysis and serves as a source of organic nitrogen as well as carbon source for PHA-free biomass with high production rate in fermentation process. Nitrogen is a limiting factor to control PHA production during the fermentation process. It is available for bacterial growth from hydrolyzed waste streams as well as added separately as NH4OH solution. Selected microbial strains are used to produce PHA from this substrate. The focus of the paper is about an overview of the whole process with the main focus on hydrolysis, to look for the possibility of using offal hydrolysis as an organic nitrogen substitute. The process design is optimized by minimizing waste streams and energy losses through cleaner production. Ecological evaluation of the process design will be done through footprint calculation according to Sustainable Process Index methodology. 相似文献
22.
He-zong Li Xiang-huai DongYu Shen Rui ZhouAlexander Diehl Hinnerk HagenahUlf Engel Marion MerkleinJian Cao 《Journal of Materials Processing Technology》2012,212(3):653-661
Microbending experiments of brass foils were conducted and demonstrated clear size effects, i.e., the normalized bending moment increased with the reduction of foil thickness. The experiments were modeled using the classical plasticity model and three strain-gradient plasticity models. A modified Nix-Gao model was proposed to consider the number of twins across the thickness direction in strain hardening. It was found that the proposed model could better predict the normalized bending moment for both fine-grain and coarse-grain foils and the proposed equation for material intrinsic length could better capture the physics of material deformation. Furthermore, micro-hardness distributions in the bending area were measured and obvious lower-hardness region was found in the middle layer of fine-grain foils instead of coarse-grain foils. This indicates that the modified Nix-Gao model and the assumption of fully plastic bending worked better for coarse-grain foils than for fine-grain foils. 相似文献
23.
项目名称:德国弗莱堡医疗诊所北区扩建工程-弗莱堡大学诊所急救中心业主:RegionofBaden-Wü rttem berg represented by University Construction Office建设地点:德国弗莱堡设计单位:KSP尤尔根·恩格尔事务所建筑面积:2.04万m2病床数量:56床建筑层数:3层地上,2层地下 相似文献
24.
25.
Banani Kundu Nicholas E. Kurland Subia Bano Chinmoy Patra Felix B. Engel Vamsi K. Yadavalli Subhas C. Kundu 《Progress in Polymer Science》2014
Biomaterials of either natural or synthetic origin are used to fabricate implantable devices, as carriers for bioactive molecules or as substrates to facilitate tissue regeneration. For the design of medical devices it is fundamental to use materials characterized by non-immunogenicity, biocompatibility, slow and/or controllable biodegradability, non-toxicity, and structural integrity. The success of biomaterial-derived biodevices tends to be based on the biomimetic architecture of the materials. Recently, proteins from natural precursors that are essentially structural and functional polymers, have gained popularity as biomaterials. The silks produced by silkworms or spiders are of particular interest as versatile protein polymers. These form the basis for diverse biomedical applications that exploit their unique biochemical nature, biocompatibility and high mechanical strength. This review discusses and summarizes the latest advances in the engineering of silk-based biomaterials, focusing specifically on the fabrication of diverse bio-mimetic structures such as films, hydrogels, scaffolds, nanofibers and nanoparticles; their functionalization and potential for biomedical applications. 相似文献
26.
27.
Technical short chain chlorinated paraffins (C10-C13 with 60% chlorine) were fed to 93 laying hens from 24 to 32 weeks of age in increasing concentrations of up to 100 mg/kg feed. No significant influence on health, relative organ weights or performance (laying intensity, egg weight, feed consumption) was noted. The chlorinated paraffin content of the tissues was linearly related to the concentration of short chain paraffins of the feed. The highest concentrations were found in abdominal fat, egg yolk and fatty tissues. Breast muscle, egg albumen and bile fluid contained minimal or no residues. Less than 1% of the chlorinated paraffins ingested were incorporated into the body (without head, feet, gut and feathers), whereas about 1.5% were eliminated with the egg yolk and 30% were excreted with urine and faeces. A six-week kinetic depuration study revealed a biphasic elimination with half-lifes of 4-40 min (liver, kidneys, legs, fat, blood) for the initial rapid phase, and 15-30 days (blood, fat, liver, yolk, kidneys, legs) for the terminal slow phase. 相似文献
28.
29.
H Engel B Bogen U Müller J Andersson A Rolink S Weiss 《Canadian Metallurgical Quarterly》1998,28(8):2289-2299
Two new lambda2 chain-transgenic mouse lines were established, both of which showed stable transgene expression during aging of the mice. The line L23, which expressed the transgene at low levels, exhibited normal B cell development, antibody responses and serum Ig levels. Most of the B cells in this mouse line co-expressed the transgenic lambda2 chain together with an endogenous kappa chain, thus showing poor allelic exclusion of endogenous L chains. On the other hand, high expression of the transgenic lambda2 chain in the other mouse line, L2, resulted in nearly complete exclusion of endogenous L chain isotypes. In this line, the lambda2 transgene was already detectable in the cytoplasm of all preB-II cells and some pro/preB-I cells. Its expression during these early phases obviously inhibited development of conventional B2 cells, since the B cells in the periphery of these mice were almost exclusively of the B1 type. This finding was confirmed by adoptive transfer of transgenic bone marrow into lethally irradiated recipients. Very few B cells were present in the spleen of such recipients. The serum IgM levels of L2 mice were close to normal and the majority of these IgM were associated with the transgenic lambda2 chain. Antibody responses to thymus-dependent antigens in such mice were almost exclusively found to be of IgM class. Together, these findings indicate a developmental bias leading to a predominance of B1 cells in the L2 line. 相似文献
30.
Washington Lindsay A.; Wilson Sylia; Engel Joyce M.; Jensen Mark P. 《Canadian Metallurgical Quarterly》2007,52(2):241
Objective: To develop and evaluate a new pediatric measure of community integration: the Pediatric Community Participation Questionnaire (PCPQ). Participants: 105 youths with physical disabilities. Measures: In addition to the PCPQ, demographic and disability-related questions and the Functional Disability Inventory (FDI) were administered. Results: The PCPQ demonstrated convergent validity through its high association with functional ability, discriminant validity through its ability to discriminate between ambulatory and nonambulatory participants, and excellent internal consistency. Conclusions: Community participation, an important component of positive overall development, may be particularly important for youths with physical disabilities. The findings from this study provide preliminary support for the validity and reliability of the PCPQ, supporting its use as a measure of community participation with this population. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献