全文获取类型
收费全文 | 17423篇 |
免费 | 1161篇 |
专业分类
各国政治 | 699篇 |
工人农民 | 835篇 |
世界政治 | 1128篇 |
外交国际关系 | 535篇 |
法律 | 12235篇 |
中国共产党 | 2篇 |
中国政治 | 106篇 |
政治理论 | 2955篇 |
综合类 | 89篇 |
出版年
2023年 | 77篇 |
2021年 | 87篇 |
2020年 | 427篇 |
2019年 | 445篇 |
2018年 | 564篇 |
2017年 | 578篇 |
2016年 | 659篇 |
2015年 | 504篇 |
2014年 | 533篇 |
2013年 | 1801篇 |
2012年 | 485篇 |
2011年 | 502篇 |
2010年 | 536篇 |
2009年 | 560篇 |
2008年 | 510篇 |
2007年 | 503篇 |
2006年 | 522篇 |
2005年 | 432篇 |
2004年 | 430篇 |
2003年 | 356篇 |
2002年 | 405篇 |
2001年 | 672篇 |
2000年 | 605篇 |
1999年 | 480篇 |
1998年 | 239篇 |
1997年 | 172篇 |
1996年 | 192篇 |
1995年 | 190篇 |
1994年 | 169篇 |
1993年 | 175篇 |
1992年 | 304篇 |
1991年 | 313篇 |
1990年 | 295篇 |
1989年 | 276篇 |
1988年 | 306篇 |
1987年 | 261篇 |
1986年 | 322篇 |
1985年 | 318篇 |
1984年 | 246篇 |
1983年 | 226篇 |
1982年 | 177篇 |
1981年 | 154篇 |
1980年 | 143篇 |
1979年 | 219篇 |
1978年 | 115篇 |
1977年 | 91篇 |
1975年 | 94篇 |
1974年 | 124篇 |
1973年 | 79篇 |
1972年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Salas A Prieto L Montesino M Albarrán C Arroyo E Paredes-Herrera MR Di Lonardo AM Doutremepuich C Fernández-Fernández I de la Vega AG Alves C López CM López-Soto M Lorente JA Picornell A Espinheira RM Hernández A Palacio AM Espinoza M Yunis JJ Pérez-Lezaun A Pestano JJ Carril JC Corach D Vide MC Alvarez-Iglesias V Pinheiro MF Whittle MR Brehm A Gómez J 《Forensic science international》2005,150(2-3):191-198
A qualitative and quantitative analytical method was developed and validated for the determination of 49 licit and illicit drugs in oral fluid. Small oral fluid samples, volume 1mL, were collected from volunteers using a modified Omni-Sal device and the analytes were extracted from an oral fluid/buffer mixture using a single Bond Elut Certify solid phase extraction cartridge. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-repetitive full scan mass spectrometry (GC-MS) were used in parallel to analyze the extracts for the targeted drugs. Extracts were analyzed by GC-MS in their underivatized form and as their pentafluoropropionyl derivatives. Deuterated internal standards were used for quantification of drugs of abuse by LC-MS-MS to minimize matrix effects. Methadone-d(9) and tumoxetine were used as the internal standards for quantification of non-derivatized and derivatized analytes respectively by GC-MS. Linearity was demonstrated over the range 5-200 ng/mL and limits of detection were less than 4 ng/mL for each drug analyzed. The method demonstrated acceptable recoveries for most of the analytes and good intra- and inter-day precision. Acquisition of data by repetitive full scan GC-MS allows the addition of further analytes to the target menu. 相似文献
972.
We present a review of a population of 114 immigrant Moroccan males for which an age estimation was requested. The subjects' real chronological age was confirmed by the Moroccan Embassy in Spain. The confirmed age range was between 13 and 25, with an average age of 18.1 years and a standard deviation of 2.03. The following tests were performed to arrive at the forensic estimation of age: general physical examination, carpus X-ray (Greulich and Pyle method) and dental orthopantomography to determine the degree of maturity of the third inferior molars (Demirjian's method). Carpus X-ray (skeletal age) was the most useful method, followed by Demirjian's method (dental age), as prediction factors of a chronological age of over or under 18. The combination of skeletal and dental age variables represented a significant improvement in the prediction of the chronological age of the subjects in this population, reducing the number of ethically unacceptable test errors to a minimum. 相似文献
973.
Validation of a 21-locus autosomal SNP multiplex for forensic identification purposes 总被引:8,自引:0,他引:8
Dixon LA Murray CM Archer EJ Dobbins AE Koumi P Gill P 《Forensic science international》2005,154(1):62-77
A single nucleotide polymorphism (SNP) multiplex has been developed to analyse highly degraded and low copy number (LCN) DNA template, i.e. <100 pg, for scenarios including mass disaster identification. The multiplex consists of 20 autosomal non-coding loci plus Amelogenin for sex determination, amplified in a single tube PCR reaction and visualised on the Applied Biosystems 3100 capillary electrophoresis (CE) system. Allele-specific primers tailed with shared universal tag sequences were designed to speed multiplex design and balance the amplification efficiencies of all loci through the use of a single reverse and two differentially labelled allele denoting forward universal primers. As the multiplex is intended for use with samples too degraded for conventional profiling, a computer program was specifically developed to aid interpretation. Critical factors taken into account by the software include empirically determined extremes of heterozygous imbalance (Hb) and the drop-out threshold (Ht) defined as the maximum peak height of a surviving heterozygous allele, where its partner may have dropped out. The discrimination power of the system is estimated at 1 in 4.5 million, using a White Caucasian population database. Comparisons using artificially degraded samples profiled with both the SNP multiplex and AMPFISTR SGM plus (Applied Biosystems) demonstrated a greater likelihood of obtaining a profile using SNPs for certain sample types. Saliva stains degraded for 147 days generated an 81% complete SNP profile whilst short tandem repeats (STRs) were only 18% complete; similarly blood degraded for 243 days produced full SNP profiles but only 9% with STRs. Reproducibility studies showed concordance between SNP profiles for different sample types, such as blood, saliva, semen and hairs, for the same individual, both within and between different DNA extracts. 相似文献
974.
Murphy AM 《Forensic science international》2005,154(2-3):210-213
Prehistoric Polynesian skeletal remains are frequently being recovered in New Zealand due to the increasing pace of urbanisation. Since such material must often be reinterred quickly, it is important that the sex of individuals be determined from the remains in a relatively short time. For this purpose, discriminant function analysis was utilised for sex determination of prehistoric adult New Zealand Polynesian femora (47 male and 44 female). Three measurements of the femoral head were taken and subjected to Statistical Package for the Social Sciences (SPSS) discriminant function analysis. For the discriminant functions derived, accuracy of sex determination ranged from 80.9% to 82.4%. Reduction in error over random assignment by sex ranged from 62% to 65%. 相似文献
975.
Steyn M 《Forensic science international》2005,151(2-3):279-287
In Southern Africa, human body parts are sometimes used for medicinal (muti) purposes. The human body is seen as being very powerful. Although ritual killing for this purpose is not common, some cases have been reported. This paper reports on an unusual muti murder, where the remains of two individuals were found in a medicine man's house. Three pots were found, two of which were constructed around human skulls. Various objects, such as coins, bullets, stones, human and animal bones were found inside the pots. They were decorated with beadwork, whistles, skin bangles, etc. Osteological analysis revealed that the human remains probably belonged to a young, white adult male individual, and a juvenile individual of Negroid descent. All associated objects probably have ritual significance, and some of these are discussed. 相似文献
976.
Renita?R.?Glaser M.?Lee?Van.?Horn Michael?W.?ArthurEmail author J.?David.?Hawkins Richard?F.?Catalano 《Journal of Quantitative Criminology》2005,21(1):73-102
Prevention science has produced information about risk and protective factors that predict adolescent drug use and related problem behaviors. This paper investigates the Communities That Care Youth Survey that measures multiple risk and protective factors. Using a sample of 172,628 students who participated in surveys administered in seven states in 1998, analyses were conducted to test the factor structure of these risk and protective factors and to test the equivalence of the factor models across five racial/ethnic groups (African Americans, Asians or Pacific Islanders, Caucasians, Hispanic Americans, and Native Americans), four grade levels (6th, 8th, 10th, and 12th) and both gender groups. Results support the construct validity of the surveys risk and protective factor scales and indicate that the measures are equally reliable across males and females and five racial/ethnic groups. Implications of these findings for science-based prevention planning are discussed. 相似文献
977.
978.
D M Wayte 《Journal - Forensic Science Society》1974,14(3):163-164
979.
980.
The technique of isoelectric focusing in ultra-thin polyacrylamide gels as a method of typing human red cell phosphoglucomutase (PGM1) has been studied. Typing was possible without the samples attaining true equilibrium focusing conditions. The isozyme patterns so obtained were clearly defined and free from distortion. The importance of assessing relative band intensities when interpreting the isozyme patterns is discussed. Our experience of using the technique to analyse casework material is described. 相似文献