首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3808篇
  免费   58篇
各国政治   174篇
工人农民   31篇
世界政治   580篇
外交国际关系   462篇
法律   1923篇
中国共产党   139篇
中国政治   243篇
政治理论   229篇
综合类   85篇
  2021年   29篇
  2020年   23篇
  2019年   28篇
  2018年   31篇
  2016年   16篇
  2015年   21篇
  2014年   113篇
  2013年   38篇
  2012年   236篇
  2011年   198篇
  2010年   97篇
  2009年   99篇
  2008年   214篇
  2007年   237篇
  2006年   251篇
  2005年   247篇
  2004年   196篇
  2003年   186篇
  2002年   179篇
  2001年   159篇
  2000年   162篇
  1999年   85篇
  1998年   33篇
  1997年   30篇
  1996年   33篇
  1995年   26篇
  1994年   40篇
  1993年   23篇
  1992年   25篇
  1991年   36篇
  1990年   24篇
  1989年   22篇
  1988年   110篇
  1987年   27篇
  1986年   26篇
  1985年   30篇
  1984年   34篇
  1983年   32篇
  1982年   22篇
  1981年   35篇
  1980年   34篇
  1979年   33篇
  1977年   42篇
  1976年   32篇
  1964年   27篇
  1963年   25篇
  1962年   40篇
  1961年   18篇
  1960年   22篇
  1959年   29篇
排序方式: 共有3866条查询结果,搜索用时 15 毫秒
981.
In a double murder investigation, the victims were found after a prolonged stay in a drainage canal. In spite of the expectations, fibre examination established a multitude of primary and secondary transferred fibres. One of these fibre types was a colourless polyester fibre possessing a blue coloured molten fibre end. These matched one of the types present in the suspect's blue denim trousers. The aim of this study was to verify the rarity of this peculiar fibre type and more precisely its presence in blue denim textiles. Over five hundred different blue jeans textiles were examined and only one of these presented exactly the same type. The comparison involved microscopy, microspectrophotometry in the visible range and Raman spectroscopy. The results indicate this fibre type is extremely rare in a blue jeans fabrics and that “standard” blue denim should not be disregarded in case work.  相似文献   
982.
本文从科学和法律层面介绍了摇晃婴儿综合征的有关内容,就关于摇晃婴儿综合征的科学和非科学专家证言的可采性进行了评价,称在科学和非科学专家之间正在发生一场真实的交战.  相似文献   
983.
生态现代化理论:回顾和展望   总被引:1,自引:0,他引:1  
生态现代化已经成为环境治理研究的主流理论,横跨经济学、社会学和管理学等多个学科,受到越来越多的关注。生态现代化的核心目标就是实现经济发展与环境退化的脱钩,它的六大假设已经或正在不同地区、不同层次被检验。生态现代化最为基本的要求就是解放生态,包括两大机制:通过技术创新实现经济生态化、通过制度创新实现生态经济化。生态现代化与可持续发展的不同主要体现在对代际公平的偏好程度,以及在对未来发展的乐观或悲观态度上。生态现代化理论对于指导中国社会发展的转型具有重大意义,展望其研究命题主要包括:国家生态现代化战略、环境治理模式改革、提升企业国际竞争力等。  相似文献   
984.
OASDI benefits are indexed for inflation to protect beneficiaries from the loss of purchasing power implied by inflation. In the absence of such indexing, the purchasing power of Social Security benefits would be eroded as rising prices raise the cost of living. By statute, cost-of-living adjustments (COLAs) for Social Security benefits are calculated using the Bureau of Labor Statistics (BLS) Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W). Some argue that this index does not accurately reflect the inflation experienced by the elderly population and should be changed to an elderly-specific price index such as the Experimental Consumer Price Index for Americans 62 Years of Age and Older, often referred to as the Consumer Price Index for the Elderly (CPI-E). Others argue that the measure of inflation underlying the COLA is technically biased, causing it to overestimate changes in the cost of living. This argument implies that current COLAs tend to increase, rather than merely maintain, the purchasing power of benefits over time. Potential bias in the CPI as a cost-of-living index arises from a number of sources, including incomplete accounting for the ability of consumers to substitute goods or change purchasing outlets in response to relative price changes. The BLS has constructed a new index called the Chained Consumer Price Index for All Urban Consumers (C-CPI-U) that better accounts for those consumer adjustments. Price indexes are not true cost-of-living indexes, but approximations of cost-of-living indexes (COLI). The Bureau of Labor Statistics (2006a) explains the difference between the two: As it pertains to the CPI, the COLI for the current month is based on the answer to the following question: "What is the cost, at this month ' market prices, of achieving the standard of living actually attained in the base period?" This cost is a hypothetical expenditure-the lowest expenditure level necessary at this month's prices to achieve the base-period's living standard.... Unfortunately, because the cost of achieving a living standard cannot be observed directly, in operational terms, a COLI can only be approximated. Although the CPI cannot be said to equal a cost-of-living index, the concept of the COLI provides the CPI's measurement objective and the standard by which we define any bias in the CPI. While all versions of the CPI only approximate the actual changes in the cost of living, the CPI-E has several additional technical limitations. First, the CPI-E may better account for the goods and services typically purchased by the elderly, but the expenditure weights for the elderly are the only difference between the CPI-E and CPI-W. These weights are based on a much smaller sample than the other two indices, making it less precise. Second, the CPI-E does not account for differences in retail outlets frequented by the aged population or the prices they pay. Finally, the purchasing population measured in the CPI-E is not necessarily identical to the Social Security beneficiary population, where more than one-fifth of OASDI beneficiaries are under age 62. Likewise, over one-fifth of persons aged 62 or older are not beneficiaries, but they are included in the CPI-E population. Finally, changes in the index used to calculate COLAs directly affect the amount of benefits paid, and as a result, projected solvency of the Social Security program. A switch to the CPI-E for the December 2006 COLA (received in January 2007) would have resulted in an average monthly benefit OASDI benefits are indexed for inflation to protect beneficiaries from the loss of purchasing power implied by inflation. In the absence of such indexing, the purchasing power of Social Security benefits would be eroded as rising prices raise the cost of living. By statute, cost-of-living adjustments (COLAs) for Social Security benefits are calculated using the Bureau of Labor Statistics (BLS) Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W). Some argue that this index does not accurately reflect the inflation experienced by the elderly population and should be changed to an elderly-specific price index such as the Experimental Consumer Price Index for Americans 62 Years of Age and Older, often referred to as the Consumer Price Index for the Elderly (CPI-E). Others argue that the measure of inflation underlying the COLA is technically biased, causing it to overestimate changes in the cost of living. This argument implies that current COLAs tend to increase, rather than merely maintain, the purchasing power of benefits over time. Potential bias in the CPI as a cost-of-living index arises from a number of sources, including incomplete accounting for the ability of consumers to substitute goods or change purchasing outlets in response to relative price changes. The BLS has constructed a new index called the Chained Consumer Price Index for All Urban Consumers (C-CPI-U) that better accounts for those consumer adjustments. Price indexes are not true cost-of-living indexes, but approximations of cost-of-living indexes (COLI). The Bureau of Labor Statistics (2006a) explains the difference between the two: As it pertains to the CPI, the COLI for the current month is based on the answer to the following question: "What is the cost, at this month ' market prices, of achieving the standard of living actually attained in the base period?" This cost is a hypothetical expenditure-the lowest expenditure level necessary at this month's prices to achieve the base-period's living standard.... Unfortunately, because the cost of achieving a living standard cannot be observed directly, in operational terms, a COLI can only be approximated. Although the CPI cannot be said to equal a cost-of-living index, the concept of the COLI provides the CPI's measurement objective and the standard by which we define any bias in the CPI. While all versions of the CPI only approximate the actual changes in the cost of living, the CPI-E has several additional technical limitations. First, the CPI-E may better account for the goods and services typically purchased by the elderly, but the expenditure weights for the elderly are the only difference between the CPI-E and CPI-W. These weights are based on a much smaller sample than the other two indices, making it less precise. Second, the CPI-E does not account for differences in retail outlets frequented by the aged population or the prices they pay. Finally, the purchasing population measured in the CPI-E is not necessarily identical to the Social Security beneficiary population, where more than one-fifth of OASDI beneficiaries are under age 62. Likewise, over one-fifth of persons aged 62 or older are not beneficiaries, but they are included in the CPI-E population. Finally, changes in the index used to calculate COLAs directly affect the amount of benefits paid, and as a result, projected solvency of the Social Security program. A switch to the CPI-E for the December 2006 COLA (received in January 2007) would have resulted in an average monthly benefit $0.90 higher than that received. If the December 2006 COLA had been adjusted by the Chained CPI-U instead, the average monthly benefit would have been $4.70 less than with current indexing. Any changes to the COLA that would cause faster growth in individual benefits would make the projected date of insolvency sooner, while slower growth would delay insolvency. Hobijn and Lagakos (2003) estimated that switching to the CPI-E for COLAs would move projected insolvency sooner by 3-5 years. A projection by SSA's Office of the Chief Actuary estimated that annual COLAs based on the Chained C-CPI-U beginning in 2006 would delay the date of OASDI insolvency by 4 years.  相似文献   
985.
Public agencies have discretion on the time domain, and politicians deploy numerous policy instruments to constrain it. Yet little is known about how administrative procedures that affect timing also affect the quality of agency decisions. We examine whether administrative deadlines shape decision timing and the observed quality of decisions. Using a unique and rich dataset of FDA drug approvals that allows us to examine decision timing and quality, we find that this administrative tool induces a piling of decisions before deadlines, and that these “just-before-deadline” approvals are linked with higher rates of postmarket safety problems (market withdrawals, severe safety warnings, safety alerts). Examination of data from FDA advisory committees suggests that the deadlines may impede quality by impairing late-stage deliberation and agency risk communication. Our results both support and challenge reigning theories about administrative procedures, suggesting they embody expected control-expertise trade-offs, but may also create unanticipated constituency losses.  相似文献   
986.
Evidence that political attitudes and behavior are in part biologically and even genetically instantiated is much discussed in political science of late. Yet the classic twin design, a primary source of evidence on this matter, has been criticized for being biased toward finding genetic influence. In this article, we employ a new data source to test empirically the alternative, exclusively environmental, explanations for ideological similarities between twins. We find little support for these explanations and argue that even if we treat them as wholly correct, they provide reasons for political science to pay more rather than less attention to the biological basis of attitudes and behaviors. Our analysis suggests that the mainstream socialization paradigm for explaining attitudes and behaviors is not necessarily incorrect but is substantively incomplete.  相似文献   
987.
988.
We present the case of a 70-year old woman who had elective mitral and aortic valve surgery. She underwent surgery without complications for about 4h until 4 pm. Approx. 3h after surgery her condition deteriorated. 1500ml of blood were collected in the chest drainage until 11 pm. An emergency thoracotomy in the patient's bed showed a ventricular rupture. Death occurred around 11:30 pm. At autopsy, the implants of the biological mitral and aortic valves were found to be sewn tightly. There was no vascular injury and no unusual bleedings to the mediastinum. In the left ventricular wall, a rupture of 1cm and a surrounding fresh myocardial infarction area of 10cm×6cm was noted. Preparation of the coronary arteries showed moderate coronary atherossclerosis without stenosis or clots. The left circumflex coronary artery (LCX) showed a sharp, obviously stenosing kink which had been caused by the mitral valve surgery. Exsanguination due to ventricular rupture following myocardial infarction caused by implant-related "kinking" of a coronary artery, was found to be the cause of death.  相似文献   
989.
Commercially available skin cleansing alcohol wipes and conventional swabs were investigated for their use as a universal sampling medium for the simultaneous collection of both organic and inorganic explosive residues. Six compounds with the potential to be encountered in casework [pentaerythritol tetranitrate (PETN), 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), triacetone triperoxide (TATP), ammonium nitrate, and sodium chlorate] were selected as representative target compounds. Quantities of these target compounds were deposited on four different substrates (glass, plastic, aluminium foil and laminate). Two chosen alcohol wipes demonstrated better overall performance in the recovery of both the organic and inorganic representative compounds from each of the test surfaces compared to the results obtained using conventional cotton and polyester swabs, pre-moistened with various solvents, and a direct methanol wash (used as a control). Results obtained using dry cotton swabs indicated that it was not an effective swabbing system for the collection of both organic and inorganic explosive residues on common substrates.  相似文献   
990.
After the train bombing in Madrid (Spain) on 11 March 2004, methenamine was detected in some of the specimens of Goma-2 ECO dynamite submitted to the forensic laboratories when analyzed by gas chromatography coupled with mass spectrometry detection (GC-MS). Methenamine is synthesized from formaldehyde and ammonia through a condensation reaction. However, neither methenamine nor any of these compounds were used to manufacture Goma-2 ECO dynamite. Four different experiments were designed in order to explain the presence of methenamine detected in the dynamite samples analyzed. In the first one, GC-MS was used to analyze the individual components of Goma-2 ECO provided by the manufacturer and the components mixed in a raw paste. Methenamine was detected in the manufacturer's ammonium nitrate and in the raw paste. The other experiments were designed to find the precursors sources for methenamine generation in Goma-2 ECO. Results revealed that these sources could be ammonium nitrate for ammonia and sawdust for formaldehyde. Under heating conditions, dynamite could produce these precursors, which could condense in the injection port of the GC-MS system and generate methenamine. However, methenamine was not always detected in these dynamites. This was explained by the existence of two opposite effects: (a) dynamite stability makes difficult that ammonium nitrate releases ammonia and (b) there is a gradual loss of formaldehyde in sawdust along the time. Both effects can prevent the formation of an amount of methenamine large enough to be detected.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号