全文获取类型
收费全文 | 1955篇 |
免费 | 45篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 22篇 |
综合类 | 8篇 |
化学工业 | 323篇 |
金属工艺 | 39篇 |
机械仪表 | 32篇 |
建筑科学 | 185篇 |
矿业工程 | 12篇 |
能源动力 | 41篇 |
轻工业 | 154篇 |
水利工程 | 16篇 |
石油天然气 | 14篇 |
武器工业 | 1篇 |
无线电 | 227篇 |
一般工业技术 | 284篇 |
冶金工业 | 206篇 |
原子能技术 | 16篇 |
自动化技术 | 423篇 |
出版年
2023年 | 7篇 |
2022年 | 19篇 |
2021年 | 36篇 |
2020年 | 25篇 |
2019年 | 33篇 |
2018年 | 30篇 |
2017年 | 47篇 |
2016年 | 45篇 |
2015年 | 25篇 |
2014年 | 72篇 |
2013年 | 161篇 |
2012年 | 93篇 |
2011年 | 107篇 |
2010年 | 99篇 |
2009年 | 108篇 |
2008年 | 118篇 |
2007年 | 114篇 |
2006年 | 123篇 |
2005年 | 103篇 |
2004年 | 103篇 |
2003年 | 79篇 |
2002年 | 58篇 |
2001年 | 39篇 |
2000年 | 34篇 |
1999年 | 40篇 |
1998年 | 34篇 |
1997年 | 43篇 |
1996年 | 37篇 |
1995年 | 18篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 3篇 |
1966年 | 1篇 |
排序方式: 共有2003条查询结果,搜索用时 148 毫秒
51.
Pitz M Schmid O Heinrich J Birmili W Maguhn J Zimmermann R Wichmann HE Peters A Cyrys J 《Environmental science & technology》2008,42(14):5087-5093
The apparent particle density of particulate matter with aerodynamic diameter < 2.5 microm (rho2.5) was determined at an urban site in Augsburg, Germany and its correlation with chemical composition and meteorological conditions was investigated. rho2.5 showed strong day-to-day variation from 1.05 to 2.36 g cm(-3) (5 to 95% percentile), and nearly 64% of the daily variability could be explained by a multiple variable regression model. A minimum in the morning and afternoon (about 1.5 g cm(-3)), and a maximum (near 1.8 g cm(-3)) during midday was observed. The minima represent fresh primary aerosol emissions, which were related to traffic soot particles with low density due to their agglomerate structure, especially observed in the early morning hours of weekdays. The maximum is likely due to increased secondary particle production and the presence of more aged particles with the built-up of the convectively mixed boundary layer. rho2.5 has the potential to serve as a crude tracer for chemical composition and atmospheric processing and might play an important role when considering the associations between health effects and ambient particles. 相似文献
52.
Dr Mike J Sissons Ian L Batey Sue Balfe Ray Hare Finlay MacRitchie 《Journal of the science of food and agriculture》2008,88(7):1194-1200
BACKGROUND: During the milling of durum wheat to semolina, about 10–15% of total products produced is residue flour, a lower value product than the semolina. This study investigated the potential for using the durum residue flour as an additive in bread‐making to improve its potential commercial value. RESULTS: Incorporation of residue durum flour from 102 breeding lines into a low protein flour and standard bakers' flour at 20% incorporation improved the bake loaf volume with minimal change in Mixograph dough mixing time and peak resistance in many of the lines tested. Loaf yellow b was always increased even with only a 10% incorporation. Baking flours can tolerate 20% incorporation with no deleterious affects on loaf volume and bake score. CONCLUSION: The results show a potential for using the lower value durum residue flour for baking bread of acceptable quality with a slightly higher yellow colour. This would improve the profitability for the miller and provide alternative ingredients to the baker for preparing specialty breads. Copyright © 2008 Crown in the Right of the State of New South Wales and Society of Chemical Industry 相似文献
53.
Perkins RG Sun H Watson J Player MA Gust G Paterson DM 《Environmental science & technology》2004,38(17):4640-4648
Microphytobenthic polymers mediate intertidal sediment erosion processes, through biostabilization and modifying the nature of eroded floc material. The latter is of key importance with respect to sediment transport dynamics, including floc aggregation and particle deposition. In this study, eroded floc material was analyzed by video imaging, alongside novel application of in-line laser holography (ILH). The erosion of engineered sediment was compared to that of natural estuarine sediments. Both video and holography showed an increase in floc size eroded from engineered cohesive clay sediment as a function of sediment dewatering and sediment polymer content. Estuarine sediment showed a curvilinear increase in floc size as a function of both microphytobenthic biomass and sediment colloidal polymer content when measured by video analysis. Holography did not show these functions for floc size due to temporal limitations of the current ILH methodology. An interaction of sediment polymer binding and sediment desiccation was observed for engineered sediments and, most notably, for estuarine cohesive sediments. In conclusion, engineered sediments were not accurate analogues for natural intertidal sediments, failing to reproduce eroded floc material similar to that from estuarine cohesive sediment. The size of eroded floc from estuarine sediments is a function of the complex interaction between biological and physicochemical processes, primarily algal colloidal polymer and desiccation. Holography demonstrated an excellent potential for the high-resolution imaging of eroded material but is limited by temporal constraints; the solution to this would be the development of real-time holographic video. 相似文献
54.
Thallium (TI) is a metal of great toxicological concern and its prevalence in the natural environment has steadily increased as a result of manufacturing and combustion practices. Due to its low natural abundance and increasing demand, TI is the fourth most expensive metal, thus, recovery and reuse could be a profitable endeavor. The hyperaccumulator Iberis intermedia was examined via in vivo micro-X-ray absorption near edge (micro-XANES) and micro-X-ray fluorescence (micro-XRF) spectroscopies to determine the speciation and distribution of TI within leaves of the plant. I. intermedia plants were cultivated under controlled conditions in 0, 10, and 20 mg TI kg(-1) soil leading to a shoot concentration of up to 13 430 mg TI kg(-1) dry weight plant mass during 10 weeks of growth. Live plant leaves were examined by micro-XANES and micro-XRF which determined aqueous TI(I) to be the model species distributed primarily throughout the vascular network. A direct relationship of vein size to TI concentration was observed. The high uptake of TI and high potential biomass of I. intermedia, combined with knowledge of TI speciation and compartmentation within the plant, are discussed in terms of accumulation/tolerance mechanisms, consequences for potential food chain contamination, and phytomining strategies to reclaim TI-contaminated soils, sediments, and waters. 相似文献
55.
56.
The use of incentives in partnering and alliancing has been seen as an important way of reinforcing collaboration in the short term and helping to build trust between clients and contractors in the long term. Yet only rarely has the impact of incentives on such relationships been discussed, let alone subjected to systematic investigation. This is despite a wealth of theory and research which brings into question the use of incentives and reinforcers as ways of generating motivation and commitment. Drawing upon this theoretical knowledge base and using evidence from a number of case studies of partnerships and alliances, this paper demonstrates how a number of important cognitive and social dimensions affect the use and impact of incentives, sometimes in ways contrary to those intended. The conclusion drawn is that there are important limitations to the use of incentives as means of reinforcing collaboration and developing commitment and trust, and that this raises questions more generally about the assumptions that underlie many of the practical ‘tools and techniques’ commonly associated with partnering and alliancing. 相似文献
57.
We consider the structured singular value problem with real parametric uncertainty only. Using techniques from algebraic geometry, we propose two algorithms that in principle can yield the precise value of the structured singular value at a fixed frequency. Their ability to do so depends upon their ability to find all common roots to a system of polynomial equations. The first algorithm is applicable to problems with two real parameters each of multiplicity two. The second algorithm is applicable to problems with n distinct real parameters. These algorithms have proved useful in applications to aerospace control law analysis. 相似文献
58.
Frederick Wieland Lawrence Hawley Abe Feinberg Mike Di Loreto Leo Blume Joseph Ruffles Peter Reiher Brian Beckman Philip Hontalas Steven Bellenot David Jefferson 《Concurrency and Computation》1989,1(1):35-50
This paper analyzes the performance of a discrete-event combat simulation executed on a parallel processor under control of the Time Warp Operating System. Time Warp is in a class of distributed simulation methods called Optimistic methods which have proven to be useful over a wide range of simulations. The combat simulation used for this performance study, called STB88, is a division-corps model incorporating a number of different types of computations. The speed-up for three versions of this model on the Caltech/JPL Mark III Hypercube and the BBN Butterfly parallel processors was measured relative to an efficient sequential execution of the same model on the same hardware. The results indicate that STB88 version 1 achieves a speed-up of 28.6 on 60 Mark III processors, while STB88 version 2 achieves a speed-up of 36.8 on 100 Butterfly processors. Version 3 of STB88 achieved a speed-up of 38.5 on 128 Mark III processors. The versions differed only in their interface to Time Warp. On the Butterfly, the sequential execution completed in 2 hours, while the 100 processor execution completed in 3.2 minutes. 相似文献
59.
生态建造:教育套餐和环境手册 总被引:2,自引:0,他引:2
生态建造是一个关注于传播建成环境中可持续性的需要以及促成可持续性的方式的项目。它针对于两个群体:16-19岁的学生,为他们制作了一个交互式的光盘;建造行业中的专业人员。光盘中提出了这样的问题--你的家和学校有多绿色?它说明了类似于建筑尺度和朝向的设计决策如何影响到建筑在能耗方面的表现和CO2的排放量。光盘包括了衡量如往宅温室节能效果的术语表,来解释它们对建筑的影响。这样学生们就可以对他们自己的学校和家进行评估,并提出怎样的设计可以提高它们的节能效果。如果我们想全球化地实现可持续性的未来,下一代的介入至关重要。环境手册中更深入地研究了这些问题,并关注到了其他建筑类型,如办公建筑。本文描述了正趋于完成的教育光盘和环境手册中涉及的一些根本的环境和教育因素。 相似文献
60.
Mike Engelhardt 《电子产品世界》2007,(1):156-157
关于LTspice/SwitcherCAD Ⅲ LTspice/SwitcherCAD Ⅲ是一款具集成原理图捕获能力的强大SPICE仿真工具. 相似文献