首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6373篇
  免费   162篇
各国政治   267篇
工人农民   318篇
世界政治   492篇
外交国际关系   227篇
法律   3952篇
中国政治   66篇
政治理论   1193篇
综合类   20篇
  2022年   32篇
  2021年   46篇
  2020年   86篇
  2019年   122篇
  2018年   170篇
  2017年   145篇
  2016年   152篇
  2015年   103篇
  2014年   145篇
  2013年   653篇
  2012年   165篇
  2011年   190篇
  2010年   150篇
  2009年   172篇
  2008年   198篇
  2007年   192篇
  2006年   169篇
  2005年   153篇
  2004年   178篇
  2003年   143篇
  2002年   122篇
  2001年   319篇
  2000年   283篇
  1999年   197篇
  1998年   86篇
  1997年   83篇
  1996年   58篇
  1995年   60篇
  1994年   55篇
  1993年   40篇
  1992年   129篇
  1991年   142篇
  1990年   135篇
  1989年   127篇
  1988年   118篇
  1987年   127篇
  1986年   101篇
  1985年   100篇
  1984年   96篇
  1983年   85篇
  1982年   57篇
  1981年   75篇
  1980年   36篇
  1979年   73篇
  1978年   43篇
  1975年   37篇
  1974年   49篇
  1973年   54篇
  1972年   39篇
  1971年   34篇
排序方式: 共有6535条查询结果,搜索用时 31 毫秒
961.
The 2 common carotid arteries bifurcate in the neck into the internal and external carotid arteries. The internal carotid artery enters the skull and further divides into the anterior and middle cerebral artery. During its short course in the neck, the carotid artery travels encased in the carotid sheath along with the vagus nerve and the internal jugular vein. During its course in the neck, the carotid artery is quite superficial, making it vulnerable to both penetrating and blunt traumatic injuries. We report here a case of a 40-year-old man who presented to the emergency department after sudden collapse and loss of consciousness a day after an attempted strangulation. Imaging revealed large hemorrhagic infarcts in the left anterior cerebral artery and middle cerebral artery territories as well as a smaller infarcts in the right anterior cerebral artery territory necessitating emergency decompressive hemicraniectomy. Our case report adds to the existing literature on nervous system injury due to strangulation. Physicians should be aware of the possibility of delayed presentation of neurological deficit after attempted strangulation.  相似文献   
962.
ABSTRACT: Determination of the time of death is an important consideration in forensic practice. Many methods have been attempted to accurately and systematically determine the postmortem interval (PMI). Histologic examination of the skin or appendages is one of the methods tried by few researchers. However, no attempt had been made to analyze the histologic changes in the skin and appendages simultaneously and to compare them with PMI. We sequentially studied the histologic changes of the skin and appendages in the early PMI. The results of the present study show that the skin undergoes progressive morphological changes in the postmortem period. The epidermis and the dermis appeared normal for 6 hours after death, and after this period, degenerative changes began. By 6 to 9 hours after death, degeneration began in the dermis, and by the end of 18 hours, the dermis began to disintegrate. The sweat glands appeared normal for approximately 3 to 4 hours. For 18 hours after death, the sebaceous glands and hair follicles appeared normal, and after this period, degeneration began.  相似文献   
963.
A number of dyed acrylic and acetate fibre samples were examined with plane polarized light on their dichroic behavior by optical light microscopy (OLM) and microspectrophotometry with plane polarized light (MSP-PPL). It was found that most of these low birefringent fibres possess weak dichroic effects that are very hard to observe with microscopy. However, using MSP-PPL, the linear dichroism could be measured. A comparison between the dichroic effects found for the same disperse dyes on triacetate (TrAc), diacetate (Ac), polyester (PES) and polyamide (PA) shows that the linear dichroism follows the order: PA>PES >TrAc, Ac.  相似文献   
964.
Significant needs exist for increased and better substance abuse treatment services in our nation's prisons. The TCU Organizational Readiness for Change (ORC) survey has been widely used in community-based treatment programs and evidence is accumulating for relationships between readiness for change and implementation of new clinical practices. Results of organizational surveys of correctional counselors from 12 programs in two states are compared with samples of community-based counselors. Correctional counselors perceived strong needs for new evidence-based practices but, compared to community counselors, reported fewer resources and less favorable organizational climates. These results have important implications for successfully implementing new practices.  相似文献   
965.
近年来网络犯罪数量呈快速上升的势头,但是却缺乏一种有效的取证方法来处理这些案件.调查人员通常依靠调查大量繁琐的源代码来了解犯罪模型及提取证据,但这种方式需要很多的人力与时间,并可能导致人为错误.为了克服调查人员可能出现的这些潜在错误,我们在本文中提出了一种半自动的方法来解决这些问题.该方法集成了用户视图(基于取证调查人员的高级别研究)和系统视图(基于对源代码的自动分析),来帮助调查人员精确调查的范围.本文应用此方法分析了一个真实案件,证明了方法的可行性,同时帮助调查人员高效地确定了调查范围和犯罪模型.可见这种半自动方法可以对大量有多个来源的电子证据进行有效分析,提高了网络犯罪案件取证的效率和可靠性.  相似文献   
966.
Pituitary tumor apoplexy refers to a clinical syndrome precipitated by the expansion of a pituitary adenoma by hemorrhage or infarction. Individuals may present with myriad signs, including sudden onset of severe headache, visual changes, altered mental status, cranial nerve palsies, and hormonal dysfunction. This disorder constitutes a medical emergency and warrants an expedited evaluation, diagnosis, and treatment to prevent the potential sequelae of permanent visual loss, endocrine abnormalities, or death. We report a case of sudden death from undiagnosed pituitary tumor apoplexy. The decedent was evaluated by medical personnel on three occasions in the week prior to her death for severe headache, nausea, vomiting, and photophobia. Postmortem examination demonstrated a hemorrhagic infarction of a pituitary adenoma with necrosis and expansion out of the sella turcica. The recognition of and treatment for a patient with pituitary tumor apoplexy requires a rapid multidisciplinary effort. Failure of prompt diagnosis may be fatal and require a medico-legal death investigation for sudden and unexpected death.  相似文献   
967.
Abstract: This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated “wrapped” and “naked” burials were created. Multigeophysical surveys were collected over a 3‐year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground‐penetrating radar (GPR), and grave and background “soil‐water” conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low‐resistivity anomalies, whereas the wrapped burial had small, varying high‐resistivity anomalies. GPR 110‐ to 900‐MHz frequency surveys showed the wrapped burial could be detected throughout, with the “naked” burial mostly resolved. Two hundred and twenty‐five megahertz frequency GPR data were optimal. “Soil‐water” analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target “wrapping” is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay‐rich soils.  相似文献   
968.
Anomie is a highly prominent theoretical construct in macro-social, particularly cross-national, criminological inquiry. Yet despite its prominence, it has proven to be quite elusive with regard to its measurement and, hence, making it nearly impossible to test theoretical hypotheses regarding its predictive efficacy. Although the concept, whether derived from Merton's classic conceptualization or from its current incarnation in the form of institutional anomie as developed by Messner and Rosenfeld, is multidimensional and complex in its theoretical structure, most researchers have attempted to operationalize it through simple, single-item, often surrogate/proxy measures. The present research note attempts to develop a measure that is more consistent with its multidimensional and complex nature. This more complex operationalization is then examined with regard to its efficacy at predicting cross-national levels of both homicide and theft. Our results suggest that that this new operationalization has considerable predictive efficacy, accounting for approximately one third of the variation in the cross-national level of both homicide and theft.  相似文献   
969.
Sex determination is a necessary step in the investigation of unidentified human remains from a forensic context. Teeth, as one of the strongest tissues in the human body, can be used for this purpose. Most studies of sexual dimorphism in teeth are based on the traditional mesiodistal and buccolingual crown measurements. The purpose of this study is to examine the degree of sexual dimorphism in permanent molars of modern Greeks using crown and cervical diagonal diameters, and to evaluate their applicability in sex determination. A total of 344 permanent molars in 107 individuals (53 male and 54 female) from the Athens Collection were examined. Crown and cervical diagonal diameters of both maxillary and mandibular molars were measured. It was found that males have larger molars than females and in 19 out of 24 dimensions measured male molars exceeded female molars significantly (P<0.05). The most dimorphic molars are the maxillary second molar, and the mandibular second and first molars. Although other molars were also sexually dimorphic they did not have a statistically significant difference in all dimensions. Cervical diagonal diameters have found to be more sexually diamorphic than crown diagonal diameters. In discriminant function analysis the variables entered more frequently were the cervical diagonal diameters mainly of mandibular molars. Classification accuracy was found to be 93% for the total sample, 77.4% for upper jaw, and 88.4% for the lower jaw. Accuracy rates were higher for cervical than crown diagonal diameters. The data generated from the present study suggest that this metric method can be useful and reliable for sex determination, especially when the traditional dental measurements are not applicable.  相似文献   
970.
The easily available "legal highs", which are products containing psychoactive substances, such as cathinones, piperazines and synthetic cannabinoids, are abused by adolescents in Poland and in the world as alternatives to classic drugs, such as amphetamines or marijuana. The majority of these potentially dangerous substances are still legal and they are associated with a risk of severe poisoning or even death, and provide new challenges in clinical and forensic toxicological practice. Investigations in the field of "designer drugs" may be well illustrated by the case of a suicide of a 21-year old male who ingested a specified dose of a preparation called "Amphi-bi-a" that contains bk-MBDB, chemically 2-methylamino-1-(3,4-methylenedioxyphenyl) butan-1-one, which belongs to the cathinone group, as a synthetic euphoric empathogen and psychoactive stimulant that is chemically similar to MDMA. It is one of more common components of "legal highs" examined in Poland and other countries. The documentation of the case includes a clinical assessment of the patient's health status performed during his almost 4-h hospitalization before death, autopsy and histological examinations supported by toxicological findings revealing bk-MBDB at extremely high concentrations (at 20mg/l in the blood and 33mg/kg in the liver); hence, this body of evidence contributes to knowledge in the field of "designer drugs". Inventions of designers of new psychoactive xenobiotics, which are much in demand, especially in view of the dynamic Internet marketing, which drums up narcobusiness, must be balanced by a national strategy developed by medical, legal and educational circles in the modern civilized world in order to prevent the spreading of the phenomenon.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号