全文获取类型
收费全文 | 1205篇 |
免费 | 39篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 30篇 |
综合类 | 3篇 |
化学工业 | 280篇 |
金属工艺 | 33篇 |
机械仪表 | 41篇 |
建筑科学 | 25篇 |
矿业工程 | 6篇 |
能源动力 | 57篇 |
轻工业 | 99篇 |
水利工程 | 2篇 |
石油天然气 | 32篇 |
无线电 | 115篇 |
一般工业技术 | 215篇 |
冶金工业 | 92篇 |
原子能技术 | 11篇 |
自动化技术 | 221篇 |
出版年
2023年 | 18篇 |
2022年 | 39篇 |
2021年 | 59篇 |
2020年 | 32篇 |
2019年 | 38篇 |
2018年 | 59篇 |
2017年 | 42篇 |
2016年 | 39篇 |
2015年 | 35篇 |
2014年 | 48篇 |
2013年 | 124篇 |
2012年 | 46篇 |
2011年 | 73篇 |
2010年 | 49篇 |
2009年 | 39篇 |
2008年 | 46篇 |
2007年 | 40篇 |
2006年 | 23篇 |
2005年 | 34篇 |
2004年 | 19篇 |
2003年 | 23篇 |
2002年 | 26篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 31篇 |
1997年 | 34篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有1262条查询结果,搜索用时 0 毫秒
61.
A method was developed for separation, preconcentration, and determination of La by its radioactive isotope 138La using an HPGe detector. The method was checked by comparison with ICP-MS. The detection limit (minimum detection activity) is 1.46 and 1.52 Bq kg?1 at 788.4 and 1435.8 keV lines, respectively. The Th(IV) and U(VI) are separated by precipitation. To separate Ac(III), it is extracted jointly with REEs from 0.1 M HNO3 with HDEHP and then stripped with 0.2 M HNO3, with REEs remaining in the organic phase. Lanthanum in a mixture with REEs is determined by ??-ray spectrometry. 相似文献
62.
Decade inductance boxes are widely used in electrical laboratories for calibration of instruments that measure inductance. The main aim of this paper is to construct a new inductance box providing a huge number of automated inductance steps, which are used in the laboratories to perform full automatic calibration of inductance meters. Therefore, a new inductance box has been introduced that mainly consists of three decades. The three inductance decades have the same design, but each has its four different internal inductive elements. Each decade can generate 15 different inductance values, so it is more economical and practical compared to the other ordinary decades, which produce only 10 values by using 10 internal inductive elements. 1666 different inductance values can be obtained from this inductance box, while 4096 inductance values can be obtained by the possible combinations of its three decades steps. Practical design, fabrication and specifications of this new inductance box are demonstrated in detail. It is designed to achieve relative accuracy in the range from 5 × 10?4 to 5 × 10?3. It could be used to perform full automatic inductance measurements at the National Institute of Standards, Egypt, for the first time. Comparison between an ordinary inductance box and the new introduced one has been made to validate its performance. 相似文献
63.
64.
Safaa Abdelraouf Ahmed Heba Ahmed Hani Ghada Ahmed Al Bazedi Mayyada M. H. El-Sayed Abdelghani M. G. Abulnour 《Korean Journal of Chemical Engineering》2014,31(6):924-929
Small/medium nuclear reactors (SMRs) are a promising alternative for powering large scale desalination plants. The modern generations of these systems manifest cost effectiveness and built-in safety features. The compatibility with geological and topological challenges is an added advantage. Moreover, funding opportunities and packages could be easily arranged for small/medium nuclear reactors (SMR). This mini review article provides the latest technical features of SMR nuclear plants with emphasis on pressurized light water reactors (PWR), boiling water reactors (BWR), heavy water reactors (HWR), gas cooled reactors (GCR), and liquid metal fast breeder reactors (LMFBR). Preliminary cost indicators for typical units were investigated as a part of joint effort to develop a cost database for these types of reactors. Security and safety features of small/medium reactors are identified and reviewed. This paper identifies and briefly discusses the various types of small/medium nuclear reactors to provide a preliminary evaluation and consideration of using this type of reactor in potential seawater desalination applications. 相似文献
65.
Radhouan Bouabda Bassem Jarboui Mansour Eddaly Abdelwaheb Rebaï 《Computers & Operations Research》2011
This paper addresses the permutation flowline manufacturing cell with sequence dependent family setup times problem with the objective to minimize the makespan criterion. We develop a cooperative approach including a genetic algorithm and a branch and bound procedure. The latter is probabilistically integrated in the genetic algorithm in order to enhance the current solution. Moreover, the application of the branch and bound algorithm is based upon the decomposition of the problem into subproblems. The performance of the proposed method is tested by numerical experiments on a large number of representative problems. 相似文献
66.
67.
Rana Tawfiq Almatarneh Yasser Mohamed Mansour 《Journal of Housing and the Built Environment》2013,28(3):505-528
This paper examines the advertising themes and rhetoric that have been assembled in the marketing of the Greater Cairo Region’s (GCR) newly built gated communities. We demonstrate how place-marketing strategies, in this case, selling the Egyptian dream home, draws upon specific landscape offerings and values. It shows how aspects of globalization interact with processes of urbanization in the GCR to create new landscapes of housing consumption. The globalization of mass media has influenced consumption preferences and brought new consumption choices to the GCR’s residents. This study concludes that the demand for gated communities in the GCR, in large part, has been created by developers who foster an image of these areas as symbols of ‘modernism’ and Western lifestyles. Underlying these sales efforts is the common assumption held by developers, potential buyers and segments of the larger society that the lifestyles of Western urbanization should naturally emerge as the result of economic development. 相似文献
68.
Vibration dampers are the first line of defense against shock and impacts sustained by mechanical and structural systems. Consequently, for decades, new impact damping technologies have been developed and applied in several engineering fields to attenuate undesired vibrations. Linear particle chain (LPC) impact dampers are the latest category of impact dampers being developed for the mitigation of unwanted vibrations in many systems. However, the challenges associated with prototyping such devices made their application in practical systems very limited. This paper proposes five innovative designs for the LPC impact dampers satisfying a wide range of industry needs in terms of efficiency, cost, and sustainability. The proposed designs are fabricated and tested under the same conditions to assess their efficiency in attenuating the vibration of a simple structure. Each design showed consistent behavior, but some designs outperformed others depending on the geometry, physical characteristics, and type of structure. The detailed design, experimental study, and time response comparisons are presented here to provide an initial study towards the development of practical sustainable LPC vibration dampers for real engineering applications. 相似文献
69.
New Zealand flower thrips, Thrips obscuratus (Thysanoptera: Thripidae), are attracted to ripening fruits, especially peaches. Volatiles from unripe and ripe peach fruits were collected and analyzed by gas chromatography/mass spectrometry. Six lactones were found only in ripe peach volatiles: γ-heptalactone, γ-octalactone, γ-nonalactone, 6-pentyl-2H-pyran-2-one, γ-decalactone, and δ-decalactone. When these compounds were tested individually in field-trapping experiments, three of them (γ-octalactone, γ-nonalactone, and 6-pentyl-2H-pyran-2-one) attracted New Zealand flower thrips. In another field-trapping experiment, aimed at testing various combinations of the three active compounds, no synergistic effects were found among all combinations tested; no combination caught more thrips than 6-pentyl-2H-pyran-2-one, alone. A further field-trapping experiment was conducted to determine the dose (10, 100, and 500 mg) of 6-pentyl-2H-pyran-2-one that gave the greatest catch of T. obscuratus, while also comparing it against another attractant, ethyl nicotinate, for T. obscuratus. The greatest catches in traps baited with either attractant were at loadings of 500 mg. At both 10 and 500 mg, traps baited with 6-pentyl-2H-pyran-2-one caught more T. obscuratus than those baited with the same amounts of ethyl nicotinate. 6-Pentyl-2H-pyran-2-one is a potent attractant for New Zealand flower thrips and, therefore, could be used for monitoring and control of New Zealand flower thrips. Work is underway developing monitoring and control options utilizing 6-pentyl-2H-pyran-2-one for this important pest. 相似文献
70.