全文获取类型
收费全文 | 3886篇 |
免费 | 102篇 |
国内免费 | 14篇 |
专业分类
电工技术 | 29篇 |
综合类 | 3篇 |
化学工业 | 603篇 |
金属工艺 | 56篇 |
机械仪表 | 49篇 |
建筑科学 | 155篇 |
矿业工程 | 24篇 |
能源动力 | 42篇 |
轻工业 | 427篇 |
水利工程 | 41篇 |
石油天然气 | 10篇 |
无线电 | 159篇 |
一般工业技术 | 473篇 |
冶金工业 | 1495篇 |
原子能技术 | 14篇 |
自动化技术 | 422篇 |
出版年
2022年 | 29篇 |
2021年 | 66篇 |
2020年 | 36篇 |
2019年 | 45篇 |
2018年 | 58篇 |
2017年 | 58篇 |
2016年 | 59篇 |
2015年 | 47篇 |
2014年 | 76篇 |
2013年 | 195篇 |
2012年 | 141篇 |
2011年 | 207篇 |
2010年 | 140篇 |
2009年 | 174篇 |
2008年 | 161篇 |
2007年 | 178篇 |
2006年 | 149篇 |
2005年 | 132篇 |
2004年 | 116篇 |
2003年 | 121篇 |
2002年 | 109篇 |
2001年 | 66篇 |
2000年 | 79篇 |
1999年 | 76篇 |
1998年 | 73篇 |
1997年 | 82篇 |
1996年 | 85篇 |
1995年 | 67篇 |
1994年 | 75篇 |
1993年 | 91篇 |
1992年 | 83篇 |
1991年 | 32篇 |
1990年 | 68篇 |
1989年 | 74篇 |
1988年 | 49篇 |
1987年 | 66篇 |
1986年 | 66篇 |
1985年 | 71篇 |
1984年 | 43篇 |
1983年 | 49篇 |
1982年 | 37篇 |
1981年 | 40篇 |
1980年 | 33篇 |
1979年 | 34篇 |
1978年 | 16篇 |
1977年 | 28篇 |
1976年 | 20篇 |
1975年 | 26篇 |
1974年 | 21篇 |
1973年 | 19篇 |
排序方式: 共有4002条查询结果,搜索用时 15 毫秒
41.
Narendra B. Dahotre T. Dwayne McCay Mary Helen McCay 《Materials and Manufacturing Processes》1994,9(3):447-466
A Laser Induced Liquid Phase Reaction Synthesis Assisted Joining technique is employed for SiC-particulate/Al-alloy composite to produce joints. Joints in SiC/Al-alloy composite are produced by synthesis of suitable material product as a result of interaction between composite and Ti (or Ti-alloy) reactive filler material induced by laser energy in the joint region. Such reaction product minimizes or eliminates the formation of deleterious aluminum carbide phase in the joint region depending upon the type and nature of die interfacial reactive filler material and also the laser processing parameters. A laser beam is utilized to both synthesize the interfacial reactant mixture and to heat the base material adjacent to the joint region to minimize the thermal stresses. The technique along with suitable filler material, further can be extended to a variety of metal matrix composite systems including combinations of Gr/Al, B/Al, B4C/Mg, Steel/Al, W/Al, Al2 O3 and Gr/Cu which are excellent for use in various automotive, aerospace and electronic applications. Preliminary observations describing the proof of concept of laser induced reaction joining of metal matrix composites are reported 相似文献
42.
TTI hydraulics and erosion control laboratory research field performance of erosion-control blankets
Storm water management issues facing the Texas Department of Transportation in the late 1980s led to the development of a coordinated research program with the Texas Transportation Institute. Researchers developed methodologies for evaluating the field performance of various erosion control technologies of the most widely used products within the Department's construction and maintenance operations. From these methodologies, the Hydraulics and Erosion Control Laboratory was designed and constructed. Currently, participants include private industry (manufacturers of erosion control products), transportation researchers (TTI), and the public sector (TxDOT).The results reported in this paper reflect 2 years of erosion-control blanket research. The study objectives were to determine the effectiveness of erosion-control blankets on the growth of warm-season perennial grasses and their ability to prevent sediment loss in a sloped condition.The laboratory simulates the highway environment with the sloped plots (6 m in width) located on an earthen embankment that is 300 m in length and 6.75 m in height (94 ft. by 22 ft., vertically). A randomized experimental design was replicated on two soil types (sand and clay) for each slope condition (3:1 or 2:1) with a control.In general, the results indicate better combined results relating to sediment retention and vegetation establishment performance for erosion-control blankets on sandy soils (noncohesive) regardless of slope condition (3:1 or 2:1) or material type. A minimum of 50% more sediment was retained on the sandy treatment plots and a 45% more vegetation coverage was achieved compared with the control plots. When analyzed by material type related to performance, excelsior, synthetic blends, and straw/coconut blends performed the best. For clay soils (cohesive), regardless of slope condition (3:1 or 2:1), the combined results indicate a minimum of 75% more sediment was retained and a minimum of 5% more vegetation establishment was achieved compared with the control plots. When analyzed by material type related to performance, excelsior, straw, and straw/coconut blends performed the best. 相似文献
43.
Reviews evidence concerning the congruence of the inductive and deductive models in logic and presents support for this congruence in the context of new test items designed to exemplify general-to-particular induction. Data from the Professional and Administrative Career Examination corroborate the logical foundations of deduction and induction as convergent models. Factor analysis of the items demonstrated factorial convergence, which lends additional support to the postulate of convergence. Implications for the understanding of cognitive processes and for psychometric practice are discussed in relation to such issues as the use of verbal and nonverbal test media, redundancy of measurement, and problem-solving strategies. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
44.
Using newly developed test equipment, the fatigue behavior of nylon 66 monofilaments was studied under two loading conditions, pure bending or simple torsion. For each mode, results are expressed in terms of the measured decay in stiffness with numbers of cycles over a range of maximum applied strain levels. Fatigue lifetimes are presented in S–N format where the log number of cycles of fatigue for a 40% decay in stiffness (N) is plotted as a function of applied strain (S). The failure mechanism for these fibers in each fatigue mode reflects the morphology of semicrystalline-oriented synthetic fibers. In torsion, many longitudinal cracks form around the perimeter of a fiber as the result of cleavage of the relatively weak interfibrillar bonds in nylon 66. In bending, cracks form within kink band boundaries and grow at an oblique angle to the fiber axis. © 1992 John Wiley & Sons, Inc. 相似文献
45.
Contends that tests in repeated-measures designs based on MANOVA are free of sphericity assumptions, and with modern computing software, MANOVA is straightforward to use, even for complex designs and nontraditional hypotheses. A general strategy for implementing MANOVA within statistical computing packages is presented. Regular (preplanned) tests and simultaneous (post hoc) tests are illustrated for a variety of designs and hypotheses. Optimal contrasts for unbalanced repeated measures designs are appended. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
46.
Mary S Patil GV Kulkarni AV Kulkarni MJ Joshi SR Mehendale SS Giri AP 《Proteomics. Clinical applications》2012,6(1-2):79-90
The coevolution of genomics and proteomics has led to advancements in the field of diagnosis and molecular mechanisms of disease. Proteomics is now stepping into the field of obstetrics, where early diagnosis of pregnancy complication such as preeclampsia (PE) is imperative. PE is a multifactorial disease characterized by hypertension with proteinuria, which is a leading cause of maternal and neonatal morbidity and mortality occurring in 5-7% of pregnancies worldwide. This review discusses the probable molecular mechanisms that lead to PE and summarizes the proteomics research carried out in understanding the pathogenicity of PE, and for identifying the candidate biomarker for diagnosis of the disease. 相似文献
47.
48.
Microsystem Technologies - Tuberculosis is a contagious disease caused by the bacteria, Mycobacterium Tuberculosis. Early detection of TB is vital to increase the chances of cure. In this paper, a... 相似文献
49.
Isenberg P Fisher D Paul SA Morris MR Inkpen K Czerwinski M 《IEEE transactions on visualization and computer graphics》2012,18(5):689-702
Co-located collaboration can be extremely valuable during complex visual analytics tasks. We present an exploratory study of a system designed to support collaborative visual analysis tasks on a digital tabletop display. Fifteen participant pairs employed Cambiera, a visual analytics system, to solve a problem involving 240 digital documents. Our analysis, supported by observations, system logs, questionnaires, and interview data, explores how pairs approached the problem around the table. We contribute a unique, rich understanding of how users worked together around the table and identify eight types of collaboration styles that can be used to identify how closely people work together while problem solving. We show how the closeness of teams’ collaboration and communication influenced how they performed on the task overall. We further discuss the role of the tabletop for visual analytics tasks and derive design implications for future co-located collaborative tabletop problem solving systems. 相似文献
50.
Arivazhagan L. Nirmal D. Reddy P. Pavan Kumar Ajayan J. Godfrey D. Prajoon P. Ray Ashok 《SILICON》2021,13(9):3039-3046
Silicon - In this paper, AlGaN/GaN High Electron Mobility Transistor (HEMT) with stacked passivation (Diamond/SiN) is proposed and investigated. The implementation of stacked passivation in HEMT... 相似文献