全文获取类型
收费全文 | 21185篇 |
免费 | 548篇 |
国内免费 | 3篇 |
专业分类
财政金融 | 2583篇 |
工业经济 | 1067篇 |
计划管理 | 2501篇 |
经济学 | 3427篇 |
综合类 | 186篇 |
运输经济 | 90篇 |
旅游经济 | 174篇 |
贸易经济 | 2226篇 |
农业经济 | 681篇 |
经济概况 | 2177篇 |
水利工程 | 6567篇 |
邮电经济 | 57篇 |
出版年
2020年 | 219篇 |
2019年 | 297篇 |
2018年 | 501篇 |
2017年 | 554篇 |
2016年 | 529篇 |
2015年 | 299篇 |
2014年 | 480篇 |
2013年 | 1646篇 |
2012年 | 683篇 |
2011年 | 692篇 |
2010年 | 496篇 |
2009年 | 623篇 |
2008年 | 597篇 |
2007年 | 654篇 |
2006年 | 579篇 |
2005年 | 554篇 |
2004年 | 556篇 |
2003年 | 409篇 |
2002年 | 356篇 |
2001年 | 342篇 |
2000年 | 366篇 |
1999年 | 361篇 |
1998年 | 384篇 |
1997年 | 365篇 |
1996年 | 332篇 |
1995年 | 301篇 |
1994年 | 313篇 |
1993年 | 358篇 |
1992年 | 393篇 |
1991年 | 334篇 |
1990年 | 329篇 |
1989年 | 297篇 |
1988年 | 287篇 |
1987年 | 299篇 |
1986年 | 296篇 |
1985年 | 325篇 |
1984年 | 311篇 |
1983年 | 292篇 |
1982年 | 287篇 |
1981年 | 315篇 |
1980年 | 303篇 |
1979年 | 313篇 |
1978年 | 300篇 |
1977年 | 299篇 |
1976年 | 281篇 |
1975年 | 216篇 |
1974年 | 236篇 |
1973年 | 222篇 |
1972年 | 186篇 |
1971年 | 181篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
51.
V. I. Shtykov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1998,32(8):459-462
Conclusions 1. Use of dewatering systems based on voidless drainage is most effective when dewatering slightly permeable soils in regions
with a deep seasonal frost.
2. Two-story drainage with the upper and lower stories spaced 30 m apart accelerates the discharge of gravitational water
from the arable layer. Results of observations on two-story drainage in experimental-production sections indicated that it
discharges 2 – 3.8 times more water than systematic tubular drainage with an interdrain spacing of 10 m and a 0.2-m thick
three-dimensional filter of a sandy-gravelly mixture.
3. It is recommended to use crushed stone and porous-clay gravel with a fineness of 10 – 20 mm as a filler. In that case,
protection of the drain filler is, as a rule, required only from the intrusion of soil from above during construction in cohesive
soils with a plasticity indexW
p≥7.
4. seepage rate in a voidless drain should be lower than the scouring velocity for the soil in which the voidless drainage
is placed. In the opposite case, it is necessary to lower the grade of the drains or select a filler gradation such that the
seepage rate in the drain be lower than the scouring velocity.
Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 8, pp. 41–43, August, 1998. 相似文献
52.
Li Wang ping Mechanics Department Huazhong University of Science Technology Wuhan P.R.China Yeo K.S. Khoo B.C. Mechanical Production Engineering Department National University of Singapore 《水动力学研究与进展(B辑)》1999,(3)
1. INTRODUCTIONThemaingoalofthispaperistoexplorethepossibilitytolearnmoreaboutthemechanismofturbulentboundarylayerflowinteractionsanditseffectsoncompliantwallperformance.Therearecertainprerequisiteconditionstofurtherthestudyonthemechanism,i.e.theco… 相似文献
53.
A. V. Mishuev S. I. Levina A. A. Komarov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》1993,27(8):484-487
Conclusion On the basis of data of model tests it can be stated that substantial deformation of the Usoi landslide will not be observed as a result of a surge overtopping it with the proposed parameters.Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 38–40, August, 1993. 相似文献
54.
The introduction of traffic management schemes has been one response of the National Parks to the problem of ever-increasing car-borne visitors and the consequent damage caused to the rural environment. By reviewing these schemes and by determining and explaining attitudes towards one particular traffic management experiment, the paper aims to deduce lessons for future policy. The analysis, based on two visitor surveys, suggests that the likelihood of success is improved when schemes are integrated, containing both ‘carrot’ and ‘stick’ elements. Since public perceptions are also found to be pivotal to its success, appropriate marketing of a scheme is vital. The paper concludes, however, that to achieve the fundamental objective of greater accessibility with less mobility, a more wide-ranging marketing effort is required intended to engender a sea change in attitude towards both the car and public transport. 相似文献
55.
56.
The paper deals with effects of price changes on measurement of poverty. It is shown that there are situations, when prices and nominal incomes change, a higher nutritional intake or an increase in commodity consumption of the poor can be associated with higher poverty gaps and a higher poverty index of the society. A positive relationship of this kind is quite counter-intuitive in the context of poverty measurement. This is caused by the adjustment of the poverty line and/or incomes of one situation by the prices of the other for the purpose of comparison.
相似文献57.
The 1992–93 recession in the western states of Germany has been attributed, in substantial measure, to the macroeconomic consequences of policies to finance unification. Studies of the costs of unification have not attempted to measure the burden of the recession. We estimate a dynamic, panel model of household incomes using data from the German Socio-Economic Panel (GSOEP) and use it to forecast what these incomes would have been in 1992–94 without a recession. Using a ratio of actual to forecast incomes, we compare the relative burden of the recession across households. Our findings suggest that western households below the median income bore the brunt of the combined impact of unification and the recession of 1992–93.
JEL classification: P3, D3, E3. 相似文献
JEL classification: P3, D3, E3. 相似文献
58.
59.
The Private Finance Initiative (PFI) was launched by the United Kingdom Government in 1992 in order to encourage the private sector in the UK to become more involved in public sector development projects. A key theme of the initiative was that the public should receive 'value for money'. This article investigates the accounting issue as to whether or not the private or the public sector should record any property related to PFI projects on balance sheet. It argues that although both HM Treasury and the Accounting Standards Board (ASB) might agree on the accounting principles, the practical impact is that in order for related properties to stay off the public sector's balance sheet, substantial risk needs to be transferred to the private sector. As a consequence of this, the objective of providing value for money to the public may not be achieved. 相似文献
60.