全文获取类型
收费全文 | 2010篇 |
免费 | 120篇 |
专业分类
各国政治 | 195篇 |
工人农民 | 119篇 |
世界政治 | 227篇 |
外交国际关系 | 145篇 |
法律 | 1085篇 |
中国政治 | 8篇 |
政治理论 | 333篇 |
综合类 | 18篇 |
出版年
2023年 | 24篇 |
2022年 | 17篇 |
2021年 | 37篇 |
2020年 | 61篇 |
2019年 | 88篇 |
2018年 | 116篇 |
2017年 | 134篇 |
2016年 | 126篇 |
2015年 | 81篇 |
2014年 | 119篇 |
2013年 | 345篇 |
2012年 | 110篇 |
2011年 | 101篇 |
2010年 | 59篇 |
2009年 | 47篇 |
2008年 | 77篇 |
2007年 | 93篇 |
2006年 | 60篇 |
2005年 | 42篇 |
2004年 | 58篇 |
2003年 | 44篇 |
2002年 | 31篇 |
2001年 | 34篇 |
2000年 | 34篇 |
1999年 | 17篇 |
1998年 | 18篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 17篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1979年 | 3篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1965年 | 2篇 |
排序方式: 共有2130条查询结果,搜索用时 31 毫秒
871.
A custom-built ion mobility spectrometer has been used to obtain the IMS spectra of cocaine, heroin, amphetamine sulfate and LSD at different drug concentrations and desorption temperatures. Practical detection limits for these four drugs were obtained as a function of desorber temperature and for heroin as a function of analysis time. Spectral and ionization interferences for each of the four drugs of interest were determined. Spectral interferences by innocuous materials are few; ionization interferences occur only at very high ratios of the mass of innocuous material to that of the drug of interest. 相似文献
872.
873.
Hédouin V Bourel B Martin-Bouyer L Bécart A Tournel G Deveaux M Gosset D 《Journal of forensic sciences》1999,44(2):351-353
This study concerns the determination of morphine concentrations in fly larvae reared on rabbits administered different concentrations of morphine and a correlation between concentrations of the drug in larvae and tissues. Three rabbits (R1, R2 and R3) were given dosages of 12.5, 25.0 and 50.0 mg/h of morphine over a 3 h period via continuous ear artery perfusion. These dosages and time of perfusion were calculated to create tissue concentrations of morphine similar to those encountered in human death due to overdose. Morphine blood level plateau was attained after 1 h of perfusion. A fourth rabbit was used as a control. To evaluate drug concentrations, tissues were sampled using a coelioscopic technique. Approximately 400 eggs of Lucilia sericata, all of the same age category, were placed in eyes, nostrils and mouth of each rabbit carcass. Larvae and puparia were regularly collected from each rabbit for toxicological analysis. The concentrations of the drug in the tissues sampled were determined to be similar to those normally encountered in human overdoses and were correlated with the dosage of morphine that had been administered. Morphine was detected in all larvae and pupae fed on tissues from carcasses administered morphine, except for puparia from the colony fed on the R1 animal which received 12.5 mg/h dosage of morphine. All samples from the control rabbit were negative for morphine. Concentrations of morphine in larvae reared on rabbit carcasses containing morphine were 30 to 100 times lower than the concentrations found in the tissues. A correlation between the tissue concentrations and larval concentrations was found in only 3rd instar larvae (80 to 140 h following hatching). No correlations were found between administered dosages, tissue concentrations and younger larvae, prepuparial larvae or puparia. 相似文献
874.
Is local politics local? French evidence 总被引:2,自引:0,他引:2
Abstract. In advanced democracies, are local political decisions determined by local events? Or are they really shaped by national forces? For the United States case, the evidence on this question is mixed. For the French case, the focus here, the evidence is also mixed, but less hard. In fact, for cantonal elections, in many ways archtypical local affairs, relevant systematic findings are virtually absent. We ask whether the cantonal elections of the Fifth Republic can be better understood as national, rather than local, contests. Our analysis leads us to the conclusion that the basic answer is, ‘yes’. There appear several theoretical reasons for this, which we give an account of. Further, we go on to show that cantonal races can actually serve as barometers to forecast upcoming national races. 相似文献
875.
876.
877.
Witting MD Furuno JP Hirshon JM Krugman SD Périssé AR Limcangco R 《Journal of interpersonal violence》2006,21(5):585-596
Emergency department (ED) screening for intimate partner violence (IPV) faces logistic difficulties and has uncertain efficacy. We surveyed 146 ED visitors and 108 ED care providers to compare their support for ED IPV screening in three hypothetical scenarios of varying IPV risk. Visitor support for screening was 5 times higher for the high-risk (86%) than for the low-risk (17%) scenario. Providers showed significantly more support for the need for ED IPV screening than visitors. Controlling for confounding by gender, race, experience with IPV, hospital, and marital status did not affect comparisons between groups. These responses indicate greater support for IPV screening in the ED for high-risk than for low-risk cases, particularly among visitors. 相似文献
878.
Balázs Égert Rebeca Jiménez-Rodríguez Evžen Kočenda Amalia Morales-Zumaquero 《Economic Change and Restructuring》2006,39(1-2):85-103
This paper extends the sparse existing literature on structural breaks in emerging markets in Central and Eastern Europe by analyzing structural breaks in the intercept, trend and variance of monthly key macroeconomic variables, such as industrial production, inflation, monetary aggregates, nominal exchange rates and series related to the labor market. Using the Bayesian procedure developed by Wang and Zivot (2000, A Bayesian time series model of multiple structural changes in level, trend and variance. J Busi Econom 18:374–386), we provide strong evidence in favor of multiple structural breaks in the series under study. As most of the existing empirical literature on European emerging markets does not sufficiently deal with structural breaks, the instability found in this paper has important implications for macro-econometric modeling as well as the ensuing recommendations for economic policy. 相似文献
879.
The term Aqua-eroticum was first introduced in 1984 by Sivaloganathan to describe the unusual autoerotic death of a man using submersion as an asphyxia method. This was the first case of that kind, and since then, no other case of autoerotic submersion has been reported, nor other autoerotic fatality in open water. Here we report the case of a 25-year-old man, nude under a home-made plastic body suit, overdressed for the season with winter clothes and restrained by complex bondage. He was submersed, tied underwater to a boat and was using a home-made diving apparatus for air supply. Death was ruled as accidental autoerotic asphyxia from rebreathing, caused by the faulty air-supply device. 相似文献
880.
Detection and quantification of the age-related point mutation A189G in the human mitochondrial DNA 总被引:2,自引:0,他引:2
Thèves C Keyser-Tracqui C Crubézy E Salles JP Ludes B Telmon N 《Journal of forensic sciences》2006,51(4):865-873
Mutation analysis in the mitochondrial DNA (mtDNA) control region is widely used in population genetic studies as well as in forensic medicine. Among the difficulties linked to the mtDNA analysis, one can find the detection of heteroplasmy, which can be inherited or somatic. Recently, age-related point mutation A189G was described in mtDNA and shown to accumulate with age in muscles. We carried out the detection of this 189 heteroplasmic point mutation using three technologies: automated DNA sequencing, Southern blot hybridization using a digoxigenin-labeled oligonucleotide probe, and peptide nucleic acid (PNA)/real-time PCR combined method on different biological samples. Our results give additional information on the increase in mutation frequency with age in muscle tissue and revealed that the PNA/real-time PCR is a largely more sensitive method than DNA sequencing for heteroplasmy detection. These investigations could be of interest in the detection and interpretation of mtDNA heteroplasmy in anthropological and forensic studies. 相似文献