全文获取类型
收费全文 | 1931篇 |
免费 | 82篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 13篇 |
综合类 | 4篇 |
化学工业 | 322篇 |
金属工艺 | 38篇 |
机械仪表 | 36篇 |
建筑科学 | 65篇 |
矿业工程 | 3篇 |
能源动力 | 44篇 |
轻工业 | 140篇 |
水利工程 | 24篇 |
石油天然气 | 12篇 |
武器工业 | 4篇 |
无线电 | 221篇 |
一般工业技术 | 382篇 |
冶金工业 | 411篇 |
原子能技术 | 12篇 |
自动化技术 | 284篇 |
出版年
2023年 | 26篇 |
2022年 | 32篇 |
2021年 | 52篇 |
2020年 | 41篇 |
2019年 | 48篇 |
2018年 | 64篇 |
2017年 | 48篇 |
2016年 | 63篇 |
2015年 | 48篇 |
2014年 | 58篇 |
2013年 | 133篇 |
2012年 | 106篇 |
2011年 | 158篇 |
2010年 | 123篇 |
2009年 | 108篇 |
2008年 | 105篇 |
2007年 | 100篇 |
2006年 | 83篇 |
2005年 | 70篇 |
2004年 | 49篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 21篇 |
2000年 | 23篇 |
1999年 | 23篇 |
1998年 | 50篇 |
1997年 | 42篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 22篇 |
1993年 | 20篇 |
1992年 | 7篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 11篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1957年 | 5篇 |
排序方式: 共有2015条查询结果,搜索用时 15 毫秒
1.
Dr. W. Mack 《Acta Mechanica》1989,77(1-2):91-99
Summary The axisymmetric bulging of circular cylindrical rubber bars under end thrust is investigated. The results for different forms of the strain energy function are compared with experimental results.With 2 Figures 相似文献
2.
P. H. Eaves J. J. Spadaro E. L. D’Aquin A. J. Crovetto V. O. Cirino Mack F. Stansbury C. L. Hoffpauir 《Journal of the American Oil Chemists' Society》1956,33(12):639-645
Summary and Conclusions Crude lipides fractions were produced from raw, tempered, and cooked meats from two lots of cottonseed by a series of successive
stepwise extractions, designed to obtain fractional portions of the total lipides in the order of the difficulty of their
extraction. The proximate composition of the crude lipides fractions was determined. It was found that the composition of
successive lipides fractions varied with the degree of exhaustiveness of extraction. The fractions obtained by more exhaustive
extraction contained greater amounts of undesirable non-neutral oil material and lesser amounts of desirable neutral oil.
It was also established that the method used in preparing meats for extraction was of paramount importance in its effect on
the composition of the crude lipides obtained. The crude lipides fractions from raw and tempered meats contained large amounts
of impurities while the crude lipides fractions similarly obtained from cooked meats were relatively low in impurities.
Crude oils equivalent to varying degrees of total lipides extraction were reconstituted from the crude lipides fractions and
evaluated for refining characteristics. The impurities content of the reconstituted oils varied as the degree of total lipides
extraction and increases in the impurities content of the oils were generally reflected in disproportionate increases in refining
losses and/or refined oil color. The oils obtained from the cooked meats at all degrees of extraction were outstandingly low
in refining losses as compared to the oils from the raw and the tempered meats.
Presented in two parts at the spring meeting, American Oil Chemists’ Society, New Orleans. La., Apr. 18–20, 1955, and at the
fall meeting, Philadelphia, Pa., Oct. 10–12, 1995.
One of the laboratories of the Southern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture. 相似文献
3.
A high temperature Seebeck coefficient measurement apparatus with various features to minimize typical sources of error is designed and built. Common sources of temperature and voltage measurement error are described and principles to overcome these are proposed. With these guiding principles, a high temperature Seebeck measurement apparatus with a uniaxial 4-point contact geometry is designed to operate from room temperature to over 1200 K. This instrument design is simple to operate, and suitable for bulk samples with a broad range of physical types and shapes. 相似文献
4.
A taxonomy for and analysis of multi-person-display ecosystems 总被引:2,自引:2,他引:0
Interactive displays are increasingly being distributed in a broad spectrum of everyday life environments: they have very
diverse form factors and portability characteristics, support a variety of interaction techniques, and can be used by a variable
number of people. The coupling of multiple displays creates an interactive “ecosystem of displays”. Such an ecosystem is suitable for particular social
contexts, which in turn generates novel settings for communication and performance and challenges in ownership. This paper
aims at providing a design space that can inform the designers of such ecosystems. To this end, we provide a taxonomy that
builds on the size of the ecosystem and on the degree of individual engagement as dimensions. We recognize areas where physical
constraints imply certain kinds of social engagement, versus other areas where further work on interaction techniques for
coupling displays can open new design spaces. 相似文献
5.
Paine SW Barton P Bird J Denton R Menochet K Smith A Tomkinson NP Chohan KK 《Journal of molecular graphics & modelling》2010,29(4):529-537
In silico models that predict the rate of human renal clearance for a diverse set of drugs, that exhibit both active secretion and net re-absorption, have been produced using three statistical approaches. Partial Least Squares (PLS) and Random Forests (RF) have been used to produce continuous models whereas Classification And Regression Trees (CART) has only been used for a classification model. The best models generated from either PLS or RF produce significant models that can predict acids/zwitterions, bases and neutrals with approximate average fold errors of 3, 3 and 4, respectively, for an independent test set that covers oral drug-like property space. These models contain additional information on top of any influence arising from plasma protein binding on the rate of renal clearance. Classification And Regression Trees (CART) has been used to generate a classification tree leading to a simple set of Renal Clearance Rules (RCR) that can be applied to man. The rules are influenced by lipophilicity and ion class and can correctly predict 60% of an independent test set. These percentages increase to 71% and 79% for drugs with renal clearances of < 0.1 ml/min/kg and > 1 ml/min/kg, respectively. As far as the authors are aware these are the first set of models to appear in the literature that predict the rate of human renal clearance and can be used to manipulate molecular properties leading to new drugs that are less likely to fail due to renal clearance. 相似文献
6.
An examination into the effects of carried military equipment on the performance of two tactical combat movement simulations was conducted. Nineteen Airfield Defence Guards performed a break contact (five 30-m sprints) and a fire and movement simulation (16 6-m bounds) in five load conditions (10–30 kg). Heavier loads significantly increased movement duration on the break contact (0.8%/kg load) and fire and movement (1.1%/kg). Performance deterioration was observed from the beginning to the end of the series of movements (bounds or sprints) with deterioration becoming significantly greater in heavier load conditions. Inter-individual variation between slower and faster participants showed a range in load effects; 0.6, 0.8%/kg for fast and 1.0, 1.4%/kg for slow (break contact, fire and movement, respectively). Velocity profiles revealed that the initial acceleration and peak velocity were the primary determinants of performance. As the duration of these tactical combat movements reflects periods of heightened vulnerability, these findings highlight important implications for commanders.
Practitioner Summary: Increasing amounts of carried military equipment impairs the performance of tactical combat movements. Examination of inter-individual variation in velocity profiles identified that the initial acceleration and the peak velocity achieved during sprints and bounds are key determinants of overall performance. 相似文献
7.
Yongchao Tang Yue Wei Anthony F.Hollenkamp Mustafa Musameh Aaron Seeber Tao Jin Xin Pan Han Zhang Yanan Hou Zongbin Zhao Xiaojuan Hao Jieshan Qiu Chunyi Zhi 《纳微快报(英文)》2021,(11):280-293
As promising anodes for sodium-ion batteries, metal sulfides ubiquitously suffer from low-rate and high-plateau issues, greatly hindering their application in f... 相似文献
8.
Jane Clary Marcus Quigley Aaron Poresky Andrew Earles Eric Strecker Marc Leisenring Jonathan Jones 《Canadian Metallurgical Quarterly》2011,137(3):190-198
Low impact development (LID) strategies are being encouraged in many communities as an approach to reduce potential adverse impacts of development on receiving streams. Many questions exist regarding how well various LID strategies perform in different settings, just as similar questions have been raised regarding performance of traditional stormwater best management practices (BMPs). Whereas historical focus on BMP performance has been water quality concentrations or loads, characterization of volume reduction benefits for both conventional and LID practices is increasingly an objective of researchers and stormwater managers. More than a decade ago, Urban Water Resources Research Council (UWRRC) members worked to develop a set of standardized monitoring and reporting protocols for traditional BMPs and to establish a master database for the purpose of evaluating BMP performance and the factors affecting performance. This effort culminated in the International Stormwater BMP Database (www.bmpdatabase.org), which contains data for more than 360 BMPs and continues to operate as a clearinghouse for stormwater BMP data and performance analyses. During 2008–2009, the International Stormwater BMP Database project expanded to better integrate LID into the database and develop a set of metrics that can be used to characterize BMP performance with regard to surface runoff volume reduction. This paper provides a condensed overview and progress report on the LID-focused effort, including the following topics: (1)?monitoring guidance for LID at the overall site development level, (2)?an overview of recent changes to the International Stormwater BMP Database to better accommodate LID studies, (3)?a summary of LID studies currently included in the database, and (4)?a proposed approach for evaluating performance of LID studies with regard to reducing surface runoff volumes. 相似文献
9.
10.
Zeng Zhang Christine M. Jackson Aaron R. Arehart Brian McSkimming James S. Speck Steven A. Ringel 《Journal of Electronic Materials》2014,43(4):828-832
The energy band alignments of Ni/Al2O3/GaN heterostructures have been explored by internal photoemission (IPE) and capacitance–voltage (CV) measurements. By performing IPE measurements at both reverse- and forward-bias conditions, the Ni/Al2O3 Schottky barrier is found to be 2.9 ± 0.1 eV with the presence of a strong image force lowering effect, while the Al2O3/GaN conduction-band offset is determined to be 2.2 ± 0.1 eV and is insensitive to oxide electrical field. CV-based flat-band voltage analysis has further been performed on samples with different oxide thicknesses, not only confirming the IPE-measured band alignment but also revealing the presence of 3.0 × 1012 cm-2 net positive charge at the Al2O3/GaN interface. 相似文献