全文获取类型
| 收费全文 | 15497篇 |
| 免费 | 297篇 |
| 国内免费 | 2篇 |
专业分类
| 财政金融 | 2182篇 |
| 工业经济 | 860篇 |
| 计划管理 | 2053篇 |
| 经济学 | 2643篇 |
| 综合类 | 94篇 |
| 运输经济 | 78篇 |
| 旅游经济 | 166篇 |
| 贸易经济 | 1895篇 |
| 农业经济 | 705篇 |
| 经济概况 | 1884篇 |
| 水利工程 | 3194篇 |
| 信息产业经济 | 1篇 |
| 邮电经济 | 41篇 |
出版年
| 2020年 | 128篇 |
| 2019年 | 202篇 |
| 2018年 | 347篇 |
| 2017年 | 303篇 |
| 2016年 | 324篇 |
| 2015年 | 191篇 |
| 2014年 | 320篇 |
| 2013年 | 1164篇 |
| 2012年 | 515篇 |
| 2011年 | 500篇 |
| 2010年 | 354篇 |
| 2009年 | 408篇 |
| 2008年 | 431篇 |
| 2007年 | 473篇 |
| 2006年 | 443篇 |
| 2005年 | 419篇 |
| 2004年 | 398篇 |
| 2003年 | 279篇 |
| 2002年 | 288篇 |
| 2001年 | 267篇 |
| 2000年 | 279篇 |
| 1999年 | 248篇 |
| 1998年 | 232篇 |
| 1997年 | 222篇 |
| 1996年 | 238篇 |
| 1995年 | 223篇 |
| 1994年 | 216篇 |
| 1993年 | 209篇 |
| 1992年 | 246篇 |
| 1991年 | 258篇 |
| 1990年 | 248篇 |
| 1989年 | 226篇 |
| 1988年 | 182篇 |
| 1987年 | 188篇 |
| 1986年 | 203篇 |
| 1985年 | 279篇 |
| 1984年 | 261篇 |
| 1983年 | 227篇 |
| 1982年 | 235篇 |
| 1981年 | 237篇 |
| 1980年 | 232篇 |
| 1979年 | 220篇 |
| 1978年 | 214篇 |
| 1977年 | 188篇 |
| 1976年 | 204篇 |
| 1975年 | 195篇 |
| 1974年 | 169篇 |
| 1973年 | 167篇 |
| 1972年 | 144篇 |
| 1971年 | 127篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
121.
I. I. Mints I. G. Logvinenko L. E. Khodykina 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2011,44(6):480-483
This is a comparative analysis of microdamage by creep pores in the metal of steam pipes following prolonged high- (540 – 560°C) and low-temperature (512 – 530°C) operation. Microdamage at low temperatures is found to take place at considerably lower levels of equivalent stress than at high temperatures. Reducing the operating temperature after the onset of pore formation is not an effective way of enhancing the reliability and durability of bends. 相似文献
122.
123.
124.
Uwe G?tze und Burkhard Huch 《Zeitschrift für Planung & Unternehmenssteuerung》2006,17(3):229-231
Ohne Zusammenfassung 相似文献
125.
S. G. Kushner 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1998,32(3):163-167
Conclusions
Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 3, pp. 46–49, March, 1998. 相似文献
| 1. | The bulk of settlement caused by the action of the soil’s own weight occurred in the construction period and were canceled out by the margins left for settlement. |
| 2. | The actual settlement coincide with the calculated. |
| 3. | The settlements observed in section A-A are caused mainly by self-compaction of the soil, since the dynamic action of motor transport is not felt here; in section B-B by the dynamic action of the rolling stock in connection with a low value ofρ d in the track bed; in section C-C by self-compaction of soil, since dynamics from passing trains is not displayed here; along the axes of the crane tracks by the cyclicity of the crane load; the insignificant settlements of several UM marks in the dam foundation are possibly related to compaction of clays as a result of their secondary consolidation, although according to calculations the stresses from the external load die out in sands. |
| 4. | The settlements that occurred, the predicted additional settlements, as well as the sustained settlements of several marks are not hazardous for normal operation of the dam. |
126.
G. M. Pod’yakov N. N. Kozhevnikov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1998,32(6):352-355
Conclusions
Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 6, pp. 41–44, June, 1998. 相似文献
| 1. | Clearing small silted rivers in the Volgograd and Rostov regions by means of floating dredges confirms the expediency of these works for irrigating farmlands, pisciculture, and improving ecology. |
| 2. | Works on clearing and dredging small rivers have their own characteristics, which should be taken into account when working out the technical documents and performing the works. |
| 3. | Simultaneously with channel clearing, comprehensive measures should be taken to prevent erosion of the banks and pollution of the river by wastewaters. |
| 4. | The project documents should be drawn up with consideration of a multipurpose approach to the use of the river’s water resources. |
127.
E. N. Reshetnikova T. G. Balashkina 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1998,32(9):517-523
Conclusions
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 40–45, September, 1998. 相似文献
| 1. | A tendency toward an increase of seepage discharges was observed in the dam foundation and bank abutments up to 1996, having reached 549 liters/sec in 1996 versus 240 liter/sec in 1990 and 190 liters/sec expected according to the design. This indicated the development of decompression of the foundation and grout curtain. |
| 2. | After repair works with the use of cement grouts at low upper pool levels, positive changes in the seepage regime did not occur: the hydraulic connection between holes along cracks both with and across the flow remains intact; the tendency toward an increase of discharges and heads behind the grout curtain remains. |
| 3. | When designating the technology of carrying out the grouting works and materials for subsequent repair operations, it is necessary to take into account the characteristics of the seepage state of the foundation: the amount of opening of the cracks in the foundation, the high seepage velocities, the active reaction to any external actions on the structure, the communication and hydraulic connection between local stretches of the foundation. |
128.
G. P. Zanias 《Journal of Agricultural Economics》1993,44(3):418-427
The degree of spatial market integration in European Community agricultural product markets is investigated. The methodology is based on co-integration analysis. A two-step testing procedure is applied to test the existence of the ‘Law of One Price’ which should be in force if these markets are truly integrated. The results show that market integration has not been achieved in a number of cases even when MCAs are subtracted from the price series used. 相似文献
129.
130.
Trends in agricultural trade for South and Central America are documented and the reform process is discussed. Performance of the agricultural sector of the region is evaluated. Challenges for policy makers are reviewed, ranging from macroeconomic policy to science and technology. 相似文献