全文获取类型
收费全文 | 1597篇 |
免费 | 75篇 |
专业分类
各国政治 | 113篇 |
工人农民 | 123篇 |
世界政治 | 168篇 |
外交国际关系 | 115篇 |
法律 | 748篇 |
中国共产党 | 2篇 |
中国政治 | 16篇 |
政治理论 | 374篇 |
综合类 | 13篇 |
出版年
2023年 | 16篇 |
2022年 | 17篇 |
2021年 | 14篇 |
2020年 | 61篇 |
2019年 | 60篇 |
2018年 | 85篇 |
2017年 | 76篇 |
2016年 | 67篇 |
2015年 | 67篇 |
2014年 | 52篇 |
2013年 | 250篇 |
2012年 | 60篇 |
2011年 | 56篇 |
2010年 | 69篇 |
2009年 | 60篇 |
2008年 | 44篇 |
2007年 | 49篇 |
2006年 | 56篇 |
2005年 | 64篇 |
2004年 | 43篇 |
2003年 | 48篇 |
2002年 | 36篇 |
2001年 | 34篇 |
2000年 | 38篇 |
1999年 | 19篇 |
1998年 | 21篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有1672条查询结果,搜索用时 31 毫秒
191.
Yekkala R Meers C Van Schepdael A Hoogmartens J Lambrichts I Willems G 《Forensic science international》2006,159(Z1):S89-S94
The estimation of chronological age in cadavers, human remains and in living human beings by various methods is discussed. These methods, which are based on the age dependent non-enzymatic changes of l-form amino acids to d-form amino acids, mainly aspartic acid, are among the most reliable and accurate methods to date. Most of these methods use gas chromatography (GC). In this review, results of aspartic acid racemization in dentin at different targets are discussed. In addition, pre-considerations and guidelines are given for the selection of dentin from teeth. A pilot project was run to evaluate the efficiency of high performance liquid chromatography (HPLC) coupled with fluorescence detection. New buffer conditions were found to obtain stable derivatives of aspartic acid enantiomers for the estimation of racemization. 相似文献
192.
Robert T. Ammerman Jack Stevens Frank W. Putnam Mekibib Altaye Jaclyn E. Hulsmann Heather D. Lehmkuhl Jennifer C. Monroe Thomas A. Gannon Judith B. Van Ginkel 《Journal of family violence》2006,21(2):105-115
Predictors of engagement in mothers receiving home visitation in the first year of service was examined. Early engagement was studied in three ways: (1) length of time active in the program during the first year of service (duration), (2) number of visits received (quantity), and (3) gaps in service between visits (consistency). Examined visits received in 515 first-time mothers in a Healthy Families America (HFA) program. Parameters of engagement were investigated, and predictors of engagement were identified using demographics and the Kempe Family Stress Inventory. Inclusive of the Assessment Visit, 31.8% of mothers disengaged prior to the first month of service. Remaining active in the program was associated with being Caucasian, and increased parenting risk (mental health/substance abuse history, low social support, increased stress). Most mothers had fewer home visits than prescribed. Gaps in prescribed service were common, with 89.4% of mothers experiencing gaps between visits of 1 month, and dropping to 16.4% having gaps of 2 months. In contrast to findings from clinic-based interventions, early engagement in home visitation is associated with lower levels of functioning and acute needs. These findings add to a growing body of literature suggesting that increased adversity promotes engagement in prevention programs in general, and home visitation programs in particular. To the extent that mothers who are actively engaged in home visitation are likely to have increased psychosocial needs, curricula may require modification and augmentation to address these needs and optimize program effectiveness. 相似文献
193.
194.
Eckenrode BA Ramsey SA Stockham RA Van Berkel GJ Asano KG Wolf DA 《Journal of forensic sciences》2006,51(4):780-789
The Scent Transfer Unit (STU-100) is a portable vacuum that uses airflow through a sterile gauze pad to capture a volatiles profile over evidentiary items for subsequent canine presentation to assist law enforcement personnel. This device was evaluated to determine its ability to trap and release organic compounds at ambient temperature under controlled laboratory conditions. Gas chromatography-mass spectrometry (GC-MS) analyses using a five-component volatiles mixture in methanol injected directly into a capture pad indicated that compound release could be detected initially and 3 days after the time of collection. Additionally, 15 compounds of a 39-component toxic organic gaseous mixture (10-1000 parts per billion by volume [p.p.b.(v)]) were trapped, released, and detected in the headspace of a volatiles capture pad after being exposed to this mixture using the STU-100 with analysis via GC-MS. Component release efficiencies at ambient temperature varied with the analyte; however, typical values of c. 10% were obtained. Desorption at elevated temperatures of reported human odor/scent chemicals and colognes trapped by the STU-100 pads was measured and indicated that the STU-100 has a significant trapping efficiency at ambient temperature. Multivariate statistical analysis of subsequent mass spectral patterns was also performed. 相似文献
195.
The identification of unknown remains is very important. When unknown remains are found, anthropologists first determine their sex and age. The sex of most skeletons is determined by their shape. In the hyoid bone, the shape is sex related, so it can be used forensically to determine the sex. This study focused on sex-based morphometry of the hyoid bone in Koreans using digital photographs. Hyoid bones from 52 males and 33 females were examined. For each subject, we took 34 measurements from photographs using a computer program, and the data were analyzed statistically using SPSS 11.0. Twenty-one of 34 measurements had significant sex differences (p<0.05). The discriminant functions based on three measurements (X(1)-X(3)) were as follows: The accuracy of discriminant functions is 88.2% in both groups, so these can be used to distinguish males from females in a statistically significant manner. 相似文献
196.
Egan JM Rickenbach M Mooney KE Palenik CS Golombeck R Mueller KT 《Journal of forensic sciences》2006,51(6):1276-1283
Banknote evidence is often submitted after a suspect has attempted to disguise or remove red dye stain that has been released because of an anti-theft device that activates after banknotes have been unlawfully removed from bank premises. Three chlorinated compounds have been synthesized as forensic chemical standards to indicate bank security dye bleaching as a suspect's intentional method for masking a robbery involving dye pack release on banknotes. A novel, facile synthetic method to provide three chlorinated derivatives of 1-(methylamino)anthraquinone (MAAQ) is presented. The synthetic route involved Ultra Clorox bleach as the chlorine source, iron chloride as the catalyst, and MAAQ as the starting material and resulted in a three-component product mixture. Two mono-chlorinated isomers (2-chloro-1-(methylamino)anthraquinone and 4-chloro-1-(methylamino)anthraquinone) and one di-chlorinated compound (2,4-dichloro-1-(methylamino)anthraquinone) of the MAAQ parent molecule were detected by gas chromatography mass spectrometry (GC-MS), and subsequently isolated by liquid chromatography (LC) with postcolumn fraction collection. Although GC-MS is sensitive enough to detect all of the chlorinated products, it is not definitive enough to identify the structural isomers. Liquid-state nuclear magnetic resonance (NMR) spectroscopy was utilized to elucidate structurally the ortho- and para-mono-chlorinated isomers once enough material was properly isolated. A reaction mechanism involving iron is proposed to explain the presence of chlorinated MAAQ species on stolen banknotes after attempted bleaching. 相似文献
197.
Jin HJ Kwak KD Hong SB Shin DJ Han MS Tyler-Smith C Kim W 《Forensic science international》2006,158(2-3):125-130
We have analyzed variation of the mitochondrial DNA (mtDNA) hypervariable segments I and II (HVS-I and HVS-II) in 185 randomly chosen individuals from Korea to provide an expanded and reliable Korean database. Combined sequence comparison of HVS-I and HVS-II led to the identification of 167 different haplotypes characterized by 154 variable sites. One hundred and fifty-one of the haplotypes were individual-specific, 14 were found in two individuals and 2 were found in three individuals. A pairwise comparison of the 185 HVS-I/II sequences found an average of 10.11 +/- 4.63 differences between individuals. The random match probability and gene diversity for the combined hypervariable regions were estimated at 0.66% and 0.9988, respectively. Analyzing the expanded database including three previously reported data sets and the present data using haplogroup-based comparisons and comparison with closely related sequences allowed errors to be detected and eliminated, thus considerably improving data quality. Sample division comparisons based on PhiST genetic distance measures revealed no significant population differentiation in the distribution of mtDNA sequence variations between the present data set and a database in The Scientific Working Group on DNA Analysis Methods (SWGDAM), but did indicate differences from other sets of data. Based on the results of mtDNA profiles, almost all of the mtDNA types studied here could be classified into subsets of haplogroups common in east Asia, and show that the Koreans possess lineages from both the southern and the northern haplogroup complexes of east Asian populations. The new data, combined with other mtDNA sequences, demonstrate how useful comparison with closely related mtDNA sequences can be for improving database quality, as well as providing haplotype information for forensic and population genetic analyses in the Korean population. 相似文献
198.
199.
200.