全文获取类型
收费全文 | 3250篇 |
免费 | 167篇 |
专业分类
各国政治 | 215篇 |
工人农民 | 166篇 |
世界政治 | 249篇 |
外交国际关系 | 211篇 |
法律 | 1515篇 |
中国政治 | 57篇 |
政治理论 | 978篇 |
综合类 | 26篇 |
出版年
2023年 | 28篇 |
2022年 | 28篇 |
2021年 | 35篇 |
2020年 | 102篇 |
2019年 | 111篇 |
2018年 | 135篇 |
2017年 | 160篇 |
2016年 | 151篇 |
2015年 | 102篇 |
2014年 | 109篇 |
2013年 | 440篇 |
2012年 | 128篇 |
2011年 | 122篇 |
2010年 | 113篇 |
2009年 | 117篇 |
2008年 | 132篇 |
2007年 | 123篇 |
2006年 | 106篇 |
2005年 | 101篇 |
2004年 | 91篇 |
2003年 | 76篇 |
2002年 | 83篇 |
2001年 | 70篇 |
2000年 | 60篇 |
1999年 | 55篇 |
1998年 | 39篇 |
1997年 | 34篇 |
1996年 | 34篇 |
1995年 | 46篇 |
1994年 | 34篇 |
1993年 | 30篇 |
1992年 | 35篇 |
1991年 | 43篇 |
1990年 | 30篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 22篇 |
1986年 | 29篇 |
1985年 | 28篇 |
1984年 | 20篇 |
1983年 | 16篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1974年 | 6篇 |
1972年 | 7篇 |
1967年 | 10篇 |
排序方式: 共有3417条查询结果,搜索用时 15 毫秒
181.
Carrick C Collins KA Lee CJ Prahlow JA Barnard JJ 《The American journal of forensic medicine and pathology》2005,26(3):275-281
Asphyxia, not an uncommon cause of sudden death, may result from numerous etiologies. Foreign-body aspiration and strangulation are 2 extrinsic causes. Airway obstruction may also be caused by laryngeal edema, asthma, infection, or anaphylaxis. Chronic causes of asphyxia include musculoskeletal diseases (eg, muscular dystrophy, amyotrophic lateral sclerosis), neurologic disorders (eg, myasthenia gravis, multiple sclerosis), respiratory disease (eg, emphysema, chronic bronchitis), or tumors. The manner of death in cases of asphyxiation may be natural, accidental, homicide, or suicide. For the death investigator, determining the cause and manner of death can often be quite challenging.We report here 2 cases of an esophageal fibrovascular polyp causing sudden asphyxial death, review of the literature, and discussion of other differential diagnoses in the case of asphyxial death. 相似文献
182.
Health policy experts have recently sounded the warning about the severe health and economic consequences of America's growing rates of obesity. Despite this fact, obesity has only begun to enter America's political consciousness and we have little information about what average Americans think of obesity or whether they support obesity-related policies. Using unique survey data collected by the authors, this essay examines public attitudes toward obesity and obesity policy. We find that, contrary to the views of health experts, most Americans are not seriously concerned with obesity, express relatively low support for obesity-targeted policies, and still view obesity as resulting from individual failure rather than environmental or genetic sources. Given the absence of elite discourse on this problem, we also find that typical determinants of policy preferences, such as ideology or partisanship, are not good predictors of attitudes on obesity policy. Rather, with a low-valence issue such as obesity, the public utilizes other attitudinal frameworks such as their opinions on smoking policy and the environmental culpability for obesity. The implications of these findings for obesity policy and research on health-related public opinion are discussed. 相似文献
183.
This study was designed to compare the qualitative results and concentrations of methamphetamine (MA) and its metabolite amphetamine (AP) in head hair and hair collected from different parts of the body (axillae and pubis). Hair from subjects (N = 14) suspected MA users was simultaneously collected. Hair preparation involved washing step, fine cutting, overnight extraction, derivatization by the trifluoroacetic anhydride, and gas chromatography/mass spectrometry (GC/MS) using selective ion monitoring. In this study, we found a good correlation of the qualitative results for MA between head hair and hair on other parts of the body, but there were some differences in concentrations of MA and AP. Namely, the concentrations of MA and AP were higher in axillary and pubic hair than in head hair. 相似文献
184.
Sequence polymorphism of the mitochondrial DNA (mtDNA) control region, hypervariable regions HVR I, HVR II and HVR III, from 51 unrelated China Han (Yan Bian area) were determined by PCR amplification and cycle sequencing. 相似文献
185.
Shin J Lee YB 《International journal of offender therapy and comparative criminology》2005,49(4):376-391
This study reviewed the public notification policy of sexual offenders against minors in South Korea as compared to community notification programs in the United States. The study then examined the policy's impact on increasing the general public's awareness of such sexual crimes. This is based on the assumption that heightening public awareness can be a starting point in combating such crimes. Results of the data, drawn from a sample of 1,409 Koreans across the nation, showed that the notification policy enhanced public awareness. Factors related to this increase in awareness were people's concern about or familiarity with the policy and people's experience in identifying the existence of known sexual offenders in their communities. Based on the results of this study, strategies for enhancing public awareness of sexual crimes on minors were formulated. The need to develop treatment programs for sexual offenders was likewise highlighted. 相似文献
186.
Metal and metalloid multi-elementary ICP-MS validation in whole blood, plasma, urine and hair. Reference values 总被引:5,自引:0,他引:5
Goullé JP Mahieu L Castermant J Neveu N Bonneau L Lainé G Bouige D Lacroix C 《Forensic science international》2005,153(1):39-44
Four multi-elementary metal and metalloid quantification methods using inductively coupled plasma mass spectrometry (ICP-MS) were developed and validated in human whole blood, plasma, urine and hair by means of a single preparation procedure for each sample. The ICP-MS measurements were performed using a Thermo Elemental X7CCT series and PlasmaLab software without a dynamic reaction cell. With this procedure 27-32 elements can be simultaneously quantified in biological matrices: Li, Be, B, Al, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Ba, W, Pt, Hg, Tl, Pb, Bi, U. Whole blood, plasma and urine samples (0.4 ml each) were diluted with purified water, acid, triton X100 and butanol. Rhodium was used as internal standard. The urine sample results were corrected for enzymatic creatinine determination. Twenty-five milligrams hair samples were acid mineralized after a decontamination procedure and diluted as previously described for biological fluids. To be validated, each element had to show linearity with a correlation coefficient higher than 0.99. The intra-assay and inter-assay inaccuracy, measured as the variation coefficient, were below 5 and 10% respectively. Global performance was assessed by a quality control program. Our laboratory is a registered participant of the Institut National de Santé Publique du Québec (Sainte-Foy, Canada) inter-laboratory comparison program for whole blood, urine, and beard hair of non-occupationally exposed individuals spiked with selected elements. In our study multi-element metal and metalloid analysis was assessed for 27 elements in whole blood, 27 elements in plasma, 30 elements in urine and 32 elements in hair, from 0 to 25, or 250 to 1000 ng/ml, depending on the element. Quantification limits ranged from 0.002 ng/ml (U) to 8.1 ng/ml (Al) for whole blood, from 0.002 ng/ml (U) to 7.7 ng/ml (Al) for plasma, from 0.001 ng/ml (U) to 2.2 ng/ml (Se) for urine, and from 0.2 pg/mg (Tl) to 0.5 ng/mg (B) for hair. Normal values were determined in whole blood (n=100), plasma (n=100), urine (n=100), and hair (n=45) of healthy volunteers, leading to approximately 10,000 analyses. All results are presented and discussed. Clinical toxicology and forensic toxicology applications are also reported. ICP-MS has made significant advances in the field of clinical biology, particularly in toxicological analysis. This is due to the use of extremely effective equipment that permits better clinical and forensic toxicological analysis of metal and metalloid status of each individual patient. 相似文献
187.
The prevalence and age distribution of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) in hair samples by gas chromatography/mass spectrometry (GC/MS) were studied. The recoveries obtained from hair were 97% and 99% for MDMA and MDA, respectively. The inter- and intra-assay precision and accuracy were determined. Out of 791 hair samples, 44 (5.6 %) contained MDMA and/or MDA. Out of these 44 subjects, urinalyses from 35 were negative for both MDMA and MDA, while only 9 were positive. We also evaluated concentrations of MDMA and MDA, and the metabolite-to-parent drug ratios. This study showed that the abuse of MDMA or MDA was found principally among young adults and male abusers. We found the epidemiology of ecstasy users in Korea between March 2002 and April 2003. 相似文献
188.
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
189.
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
190.
Daniel E. Ingberman 《Public Choice》1985,46(1):19-43
Stylized institutions for direct democracy referenda are examined in a dynamic full information environment with myopic voters. Competitive-agenda (median-voter) processes are contrasted with monopolistic (controlled-agenda) processes by extending existing static analyses to a class of dynamic institutions not previously characterized, the status quo reversion rule. This highlights the dependence of the progression of real equilibrium allocations over time on institutional structure. By delineating the restrictions implied by each institutional form the model explains some persistent empirical regularities. In particular, a strict ceteris paribus ordering of the magnitudes of budgets by institutional form is derived for a wide portion of the parameter space. 相似文献