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   4234篇
  免费   95篇
  国内免费   5篇
各国政治   134篇
工人农民   118篇
世界政治   178篇
外交国际关系   154篇
法律   2955篇
中国共产党   39篇
中国政治   117篇
政治理论   438篇
综合类   201篇
  2021年   33篇
  2020年   54篇
  2019年   41篇
  2018年   64篇
  2017年   62篇
  2016年   74篇
  2015年   47篇
  2014年   77篇
  2013年   322篇
  2012年   127篇
  2011年   172篇
  2010年   143篇
  2009年   125篇
  2008年   165篇
  2007年   197篇
  2006年   175篇
  2005年   136篇
  2004年   152篇
  2003年   130篇
  2002年   132篇
  2001年   167篇
  2000年   148篇
  1999年   112篇
  1998年   23篇
  1995年   22篇
  1993年   31篇
  1992年   66篇
  1991年   85篇
  1990年   87篇
  1989年   92篇
  1988年   98篇
  1987年   93篇
  1986年   77篇
  1985年   77篇
  1984年   68篇
  1983年   59篇
  1982年   25篇
  1981年   21篇
  1979年   31篇
  1978年   33篇
  1977年   22篇
  1976年   29篇
  1975年   28篇
  1974年   38篇
  1973年   38篇
  1972年   35篇
  1971年   36篇
  1970年   39篇
  1969年   32篇
  1968年   28篇
排序方式: 共有4334条查询结果,搜索用时 15 毫秒
851.
The electrostatic process for imaging indentations on documents using the ESDA device is investigated under controlled experimental settings. An in-house modified commercial xerographic developer housing is used to control the uniformity and volume of toner deposition, allowing for reproducible image development. Along with this novel development tool, an electrostatic voltmeter and fixed environmental conditions facilitate an optimization process. Sample documents are preconditioned in a humidity cabinet with microprocessor control, and the significant benefit of humidification above 70% RH on image quality is verified. Improving on the subjective methods of previous studies, image quality analysis is carried out in an objective and reproducible manner using the PIAS-II. For the seven commercial paper types tested, the optimum ESDA operating point is found to be at an electric potential near -400V at the Mylar surface; however, for most paper types, the optimum operating regime is found to be quite broad, spanning relatively small electric potentials between -200 and -550V. At -400V, the film right above an indented area generally carries a voltage which is 30-50V less negative than the non-indented background. In contrast with Seward's findings [G.H. Seward, Model for electrostatic imaging of forensic evidence via discharge through Mylar-paper path, J. Appl. Phys. 83 (3) (1998) 1450-1456; G.H. Seward, Practical implications of the charge transport model for electrostatic detection apparatus (ESDA), J. Forensic Sci. 44 (4) (1999) 832-836], a period of charge decay before image development is not required when operating in this optimal regime. A brief investigation of the role played by paper-to-paper friction during the indentation process is conducted using our optimized development method.  相似文献   
852.
李龙  汪习根 《现代法学》2001,4(1):13-19
本文旨在从法理学的高度来探讨国际法与国内法的关系。以法律规范的和谐统一作为科学地认识国际法与国内法关系的逻辑点 ,通过对法的调整机制和内在特质所具有的普遍性进行分析 ,提出了关于国际法和国内法关系的“法律规范协调说”。  相似文献   
853.
Inks from seven black and eight blue ballpoint pens were separated by a high-performance liquid chromatography (HPLC) method utilizing a photodiode array detection (PDA). A classifier flowchart was designed for the chromatographic data based on the presence or absence of certain peaks at different wavelengths to qualitatively discriminate between the inks. The same data were quantitatively classified by principal components analysis (PCA) to estimate the separation between a pair of classes of ink samples. It was found that the black ballpoint pen inks were discriminated satisfactorily utilizing two-dimensional data of the peak areas and retention times at the optimum wavelengths. The blue pens were discriminated by analyzing the chromatographic data at four different wavelengths simultaneously with a cross-validated PCA. The results of this study indicated that HPLC-PDA coupled with chemometrics could make a powerful discriminating tool for the forensic chemist, especially when analyzing extensive and/or complex data.  相似文献   
854.
Because of a shortage in the availability of human organs, xenografts have been attempted in humans with cardiac, renal, and hepatic failure, despite limited success. Use of xenografts, however, is regulated under law in various countries. In xenotransplant cases related to violation of transplantation law, determination of species of the source of tissue and organ(s) becomes highly essential. Random amplified polymorphic DNA (RAPD) protocols using six sets of arbitrary short-sequenced primers have been standardized for verifying claims of porcine cardiac and renal grafts in human transplantation cases. Six arbitrary primers used were found to generate unique amplicon patterns at 36 degrees C annealing temperature. Among the selected primers, a single primer set having the sequence 5'- GGTGCGGGAA -3' is found to be the most informative in discerning porcine tissue contamination in humans. The patterns obtained were consistent for a particular genome. The grafted organs in the studied case were analyzed to be of porcine origin.  相似文献   
855.
856.
In 2005 Indonesian and European institutes joined to start the first step for the implementation of an Ocean Operational System in the Indonesian archipelago. The system will support the decision making process for the sustainable use of marine resources, providing useful information and added value products as well as a service for an improved management of the sea with high business impact to targeted groups as public authorities and commercial operators (coastal managers, fishermen, shipping companies). In this paper the System is shortly described with its potential benefits and economic and social impacts.
A. Ribotti (Corresponding author)Email:
R. Sorgente
A. Hanggono
G. M. R. Manzella
N. Hendiarti
L. Fusco
T. R. Adi
Y. S. Djajadihardja
A. R. Farhan
M. C. G. Frederik
W. F. Ma’ruf
B. Realino
V. Rupolo
P. Ruti
M. Sadly
F. Syamsudin
B. A. Subki
  相似文献   
857.
Visas and work permits: Possible global negotiating initiatives   总被引:1,自引:0,他引:1  
We discuss global options for initiatives intended to ameliorate adverse impacts of visa and work permit systems used by national governments around the world. We first describe and document some of their effects, noting the relative lack of other research work on these issues. We then discuss proposals for a new and supplemental global visa structure which have been made as part of the Mode 4 GATS negotiations in the WTO, suggesting that the GATS/WTO may be an imperfect institutional location for negotiating on these matters. We then evaluate other approaches, including what realistically could be possible if a new body specifically created for global negotiation in the area were to be used.
John WhalleyEmail:
  相似文献   
858.
This paper presents a theoretical framework and some empirical results showing that the level of foreign aid received reduces the supply of terrorist attacks by recipient countries, as does the recipient country’s level of education. Due account is taken of endogeneity problems in producing these results. They suggest that Western democracies, which are the main targets of terrorist attacks, should invest more funds in foreign aid with a special emphasis on supporting education.  相似文献   
859.
The flow of foreign direct investment into developing countries varies greatly across countries and over time. The political factors that affect these flows are not well understood. Focusing on the relationship between trade and investment, we argue that international trade agreements—GATT/WTO and preferential trade agreements (PTAs)—provide mechanisms for making commitments to foreign investors about the treatment of their assets, thus reassuring investors and increasing investment. These international commitments are more credible than domestic policy choices, because reneging on them is more costly. Statistical analyses for 122 developing countries from 1970 to 2000 support this argument. Developing countries that belong to the WTO and participate in more PTAs experience greater FDI inflows than otherwise, controlling for many factors including domestic policy preferences and taking into account possible endogeneity. Joining international trade agreements allows developing countries to attract more FDI and thus increase economic growth.  相似文献   
860.
网络对青年社会化的效应及其对策分析   总被引:5,自引:0,他引:5  
网络开辟了青年社会化的崭新时代,为青年提供了新的广阔空间,但在其消解传统的社会化模式,带来众多积极效应的同时,也应认识到网络社会化自身的局限与副作用.对这一问题的重视和探讨,将有助于进一步促进青年社会化的健康发展.  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