全文获取类型
收费全文 | 25727篇 |
免费 | 1426篇 |
专业分类
各国政治 | 1083篇 |
工人农民 | 1095篇 |
世界政治 | 1743篇 |
外交国际关系 | 848篇 |
法律 | 17463篇 |
中国共产党 | 2篇 |
中国政治 | 167篇 |
政治理论 | 4615篇 |
综合类 | 137篇 |
出版年
2021年 | 136篇 |
2020年 | 536篇 |
2019年 | 569篇 |
2018年 | 726篇 |
2017年 | 772篇 |
2016年 | 836篇 |
2015年 | 666篇 |
2014年 | 682篇 |
2013年 | 2606篇 |
2012年 | 655篇 |
2011年 | 720篇 |
2010年 | 714篇 |
2009年 | 758篇 |
2008年 | 711篇 |
2007年 | 682篇 |
2006年 | 721篇 |
2005年 | 621篇 |
2004年 | 641篇 |
2003年 | 545篇 |
2002年 | 580篇 |
2001年 | 999篇 |
2000年 | 849篇 |
1999年 | 709篇 |
1998年 | 355篇 |
1997年 | 271篇 |
1996年 | 279篇 |
1995年 | 302篇 |
1994年 | 282篇 |
1993年 | 299篇 |
1992年 | 503篇 |
1991年 | 485篇 |
1990年 | 472篇 |
1989年 | 459篇 |
1988年 | 469篇 |
1987年 | 441篇 |
1986年 | 505篇 |
1985年 | 516篇 |
1984年 | 399篇 |
1983年 | 380篇 |
1982年 | 268篇 |
1981年 | 245篇 |
1980年 | 207篇 |
1979年 | 332篇 |
1978年 | 200篇 |
1977年 | 163篇 |
1976年 | 138篇 |
1975年 | 162篇 |
1974年 | 204篇 |
1973年 | 150篇 |
1972年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
142.
The impact of high temperatures (24 to 39 degrees C) and low to moderately high humidities (20 to 70%) on the applicability of TLC systems for drug identification was studied during a 6 month climatologic cycle in Burkina Faso (West Africa). In general, the Rf values as observed on the plates were found to be substantially affected as compared with values obtained at temperate climates. Some TLC systems were more affected than others and the largest deviations of up to 30 Rf units were at low humidities. Tropical conditions also had a negative effect on the reproducibility of Rf values. However, when an Rf-correction procedure was applied, using reference mixtures of known drugs on each plate, accuracy as well as reproducibility of the resulting Rfc values were drastically improved and data thus corrected were found to be compatible with existing TLC data bases developed under moderate climatological conditions. The impact of high to extremely high humidities (70 to 100%) remains to be investigated. 相似文献
143.
B G Rabe 《Journal of health politics, policy and law》1992,17(1):119-142
Hazardous waste management poses increasing problems for Canadian provinces and American states, given the vast quantities and types of wastes generated and the virtual inability to open new storage, treatment, or disposal facilities. The Canadian experience is very similar to the American one in many respects, except for the fact that three provinces (Alberta, Manitoba, and Quebec) have devised alternative approaches to siting that appear successful in moving beyond the political gridlock so common on this issue. In each of these cases, traditional, top-down approaches to siting have been eschewed in favor of a more comprehensive approach that includes extensive public participation, economic and social compensation packages, formal partnerships between public and private organizations, and direct links between siting proposals and other aspects of waste management, including waste reduction, recycling, and export/import control. 相似文献
144.
145.
In this study, a new method was developed for the impurity profiling of illicit MDMA tablets. The extraction efficiency, linearity, repeatability and reproducibility of the method were evaluated. Eighty two MDMA tablets coming from presumed unrelated large seizures in 2004 (n >500 tablets) were analyzed by gas chromatography mass spectrometry (GC-MS) in order to assess the discrimination power of the method. The latter was found to be practical, robust, relatively easy to perform, highly discriminative and yielding good chromatography. In addition, some new impurities were detected and identified. Their chemical structures and mass spectra are reported. 相似文献
146.
Carola Müller 《Revista de derecho y genoma humano》2005,(22):133-151
The legislator, in the German Federal Republic, has opted for a specific legal solution in relation to the protection of the embryo. Carola Müller, in this article, describes this regulation as well as the reasons that have led to its adoption. The article finishes with an exposition of the existing social discussion in German society and the effect that the law has had. 相似文献
147.
U.S. Supreme Court Justice Thurgood Marshall offered his opinion regarding the utility of public opinion polls as a tool for assessing the “evolving standards of decency” regarding capital punishment. His arguments became known as the Marshall hypotheses and spawned a considerable body of empirical testing. The three Marshall hypotheses are: (1) support for capital punishment is inversely associated with knowledge about it, (2) exposure to information about capital punishment produces sentiments in opposition to capital punishment, but (3) exposure to information about capital punishment will have no impact on those who support it for retributive reasons. The results of previous tests of these hypotheses were somewhat mixed but supportive. None of these studies, however, examined the effects of change in knowledge levels with changes, if any, in death penalty attitudes and beliefs as needed for a more complete test of the Marshall hypotheses. The present study addressed this shortcoming. The results provided mixed support for these three hypotheses. That is, death penalty supporters were somewhat less informed than death penalty opponents; exposure to death penalty information and knowledge gains tended to be associated with attitudinal change in a directions suggested by these hypotheses; but, retributivists' attitudes toward and beliefs about capital punishment were not any more resistant to change than were the attitudes and beliefs of non-retributivists. 相似文献
148.
Daniel B. Pickar 《Family Court Review》2007,45(1):103-115
Conducting child custody evaluations is one of the most complex, challenging, and sometimes risky professional endeavors that a mental health professional can perform. This article examines the professional and personal challenges which may be encountered by the evaluator. In addition to discussing the role requirements and need to maintain awareness of bias and countertransference, challenges such as coping with state board or ethics complaints and possible risks to personal safety are also addressed. Suggestions for risk management and coping with the demands of these assessments are offered, as well as the benefits and rewards of engaging in this important work. 相似文献
149.
Silvina J. Vilas-Ghiso Diana M. Liverman 《International Environmental Agreements: Politics, Law and Economics》2007,7(2):137-169
More than a decade after NAFTA (North American Free Trade Agreement) entered into force, the environmental effects of agricultural
trade liberalization in Mexico are still controversial, emerging, and not fully understood. This paper contributes to the
literature that aims to explore trends in input use in the agricultural sector in Mexico during the post-NAFTA period among
both commercial/industrial and traditional/rainfed farmers, and examines the influence of the national and multilateral institutional
framework on these outcomes. We decompose the post-NAFTA agricultural production data into scale, technique and composition
effects to estimate the impact that trade liberalization has had on the use of fertilizer and land use, two key agricultural
inputs for which reliable aggregate data is available. We conclude that among commercial farmers patterns of crop type specialization
and significant technological improvements have led to some declines in fertilizer use but they have been offset by growth
in fertilizer use associated with growing agricultural output. Among traditional farmers increased output and specialization
in land-intensive grain crops are contributing to an increase in land under cultivation and technological improvements show
the potential, but not yet not the strength, to counteract these effects. We analyse the environmental institutional framework
and rural development plans, observing that institutional weaknesses have, in several instances, reduced the environmental
benefit of technique and composition effects. We conclude with recommendations about how the Mexican agricultural sector might
reap the environmental benefits of international agricultural trade. 相似文献
150.