全文获取类型
收费全文 | 15198篇 |
免费 | 706篇 |
专业分类
各国政治 | 692篇 |
工人农民 | 601篇 |
世界政治 | 954篇 |
外交国际关系 | 486篇 |
法律 | 10038篇 |
中国共产党 | 3篇 |
中国政治 | 88篇 |
政治理论 | 2933篇 |
综合类 | 109篇 |
出版年
2020年 | 245篇 |
2019年 | 290篇 |
2018年 | 366篇 |
2017年 | 408篇 |
2016年 | 406篇 |
2015年 | 327篇 |
2014年 | 312篇 |
2013年 | 1584篇 |
2012年 | 369篇 |
2011年 | 388篇 |
2010年 | 380篇 |
2009年 | 406篇 |
2008年 | 409篇 |
2007年 | 369篇 |
2006年 | 407篇 |
2005年 | 374篇 |
2004年 | 392篇 |
2003年 | 347篇 |
2002年 | 340篇 |
2001年 | 548篇 |
2000年 | 483篇 |
1999年 | 391篇 |
1998年 | 206篇 |
1997年 | 182篇 |
1996年 | 172篇 |
1995年 | 171篇 |
1994年 | 175篇 |
1993年 | 195篇 |
1992年 | 322篇 |
1991年 | 336篇 |
1990年 | 300篇 |
1989年 | 323篇 |
1988年 | 266篇 |
1987年 | 303篇 |
1986年 | 291篇 |
1985年 | 280篇 |
1984年 | 249篇 |
1983年 | 272篇 |
1982年 | 172篇 |
1981年 | 164篇 |
1980年 | 129篇 |
1979年 | 206篇 |
1978年 | 141篇 |
1977年 | 128篇 |
1976年 | 109篇 |
1975年 | 102篇 |
1974年 | 111篇 |
1973年 | 123篇 |
1972年 | 101篇 |
1968年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
951.
952.
953.
The human teeth are a valuable source of information concerning identification and age calculation in forensic sciences. Dental treatment often causes permanent alteration of the teeth, which is visible on radiographs. The correlation of prosthetic restorations, root canal fillings and periodontal bone loss with chronological age has not yet been used for determining the completed 18th year of life in teenagers and young adults, e. g. for legal and anthropological purposes. The aim of this study was to determine whether the evaluation of such findings on radiographs correlates with the chronological age in teenagers and young adults. MATERIAL AND METHODS: The dental X-rays (orthopantomogram, OPG) of 1053 outpatients (age: 14 to 24 years) were avaluated. The values "prosthetically restored", "filled dental root", or "periodontal bone loss" were recorded for each tooth present. The data were then evaluated using statistical tools. RESULTS: The correlation between the number of prosthetically restored teeth and the chronological age is high. The positive predictive value of determining an age of at least 18 years proved to be very high. However, these findings are rarely present in this age group. The number of endodontically treated teeth correlated less exactly with age. On the other hand, the determination of periodontal bone loss gave reasonable positive predictive values for the threshold value "chronological age of 18 years or more". DISCUSSION: This study provides for the first time predictive values for the estimation whether a person is 18 years of age, based on the evaluation of teeth with prosthetic restorations, root canal fillings or periodontal bone loss on OPGs only. Whereas the number of patients with such findings is generally low in this age group, some of the positive findings can be used for age estimation as an adjunct to other sources of age calculation. The sole application of these criteria is not recommended, as sanitary conditions of the teeth depend on both social and individual circumstances. Therefore, the calculated values also reflect the culture of the sample studied. Finally, they are time-dependent and have to be compared to data from other populations. These results have some bearing on the field of forensic odontology. 相似文献
954.
955.
Samples containing DNA from two or more individuals can be difficult to interpret. Even ascertaining the number of contributors can be challenging and associated uncertainties can have dramatic effects on the interpretation of testing results. Using an FBI genotypes dataset, containing complete genotype information from the 13 Combined DNA Index System (CODIS) loci for 959 individuals, all possible mixtures of three individuals were exhaustively and empirically computed. Allele sharing between pairs of individuals in the original dataset, a randomized dataset and datasets of generated cousins and siblings was evaluated as were the number of loci that were necessary to reliably deduce the number of contributors present in simulated mixtures of four or less contributors. The relatively small number of alleles detectable at most CODIS loci and the fact that some alleles are likely to be shared between individuals within a population can make the maximum number of different alleles observed at any tested loci an unreliable indicator of the maximum number of contributors to a mixed DNA sample. This analysis does not use other data available from the electropherograms (such as peak height or peak area) to estimate the number of contributors to each mixture. As a result, the study represents a worst case analysis of mixture characterization. Within this dataset, approximately 3% of three-person mixtures would be mischaracterized as two-person mixtures and more than 70% of four-person mixtures would be mischaracterized as two- or three-person mixtures using only the maximum number of alleles observed at any tested locus. 相似文献
956.
Ecke DJ Sampath R Willett P Samant V Massire C Hall TA Hari K McNeil JA Büchen-Osmond C Budowle B 《Journal of forensic sciences》2005,50(6):1380-1385
Infectious microorganisms are important to multiple communities engaged in biodefense and biosecurity, including the agencies responsible for health, defense, law enforcement, agriculture, and drug and food safety. Many agencies have created lists of high priority infectious microorganisms to prioritize research efforts or to formally control the possession and distribution of specific organisms or toxins. However, the biological classification of infectious microorganisms is often complex and ambiguous, leading to uncertainty and confusion for scientists involved in biosecurity work. To address this problem, we created a database, known as the Microbial Rosetta Stone, which resolves many of these ambiguities and includes links to additional information on the microbes, such as gene sequence data and scientific literature. Here we discuss the efforts to coordinate organism names from pathogen lists from various governmental agencies according to biological relatedness and show the overlap of high-priority organisms from multiple agencies. To our knowledge, this is the first comprehensive coordination of pathogens, synonyms, and correct taxonomic names. The organized tables and visual aids are freely available at http://www.microbialrosettastone.com. This website provides a single location where access to information on a broad range of disease-causing organisms and toxins is available to members of the biosecurity community. 相似文献
957.
Friedman SH Hrouda DR Holden CE Noffsinger SG Resnick PJ 《Journal of forensic sciences》2005,50(6):1466-1471
Forensic hospital records of 39 severely mentally ill mothers adjudicated Not Guilty by Reason of Insanity for filicide (child murder by parents) were analyzed to describe characteristics preceding this tragedy and to suggest prevention strategies. Almost three-quarters of the mothers (72%) had previous mental health treatment. Over two thirds (69%) of the mothers were experiencing auditory hallucinations, most frequently command hallucinations, and half (49%) were depressed at the time of the offense. Over one third (38%) of the filicides occurred during pregnancy or the postpartum period, and many had a history of postpartum psychosis. Almost three-quarters (72%) of the mothers had experienced considerable developmental stressors, such as death of their own mother or incest. Maternal motives for filicide were predominantly "altruistic" (meaning murder out of love) or "acutely psychotic" (occurring in the throes of psychosis, without rational motive). Psychiatrists should perform careful risk assessments for filicide in mothers with mental illnesses. 相似文献
958.
Fartushnyĭ AF Sukhin AP Gerasimenko AI Shevchenko VV Sborshchik EA 《Sudebno-meditsinskaia ekspertiza》2005,48(2):38-41
A method was suggested for identifying reladorm and donormil in pharmaceutical drugs and biological objects. The above substances are isolated by 96% ethanol or by mixture of chloroform and isopropanol. 7 color reactions, 3 microcrystalloscopic reactions and chromatography in thin sorbent layer are suggested for identification. 相似文献
959.
Posttraumatic alterations in the cervical spine ligaments were studied clinically and psychologically in the victims with mechanical injuries of the musculoligamentous system of the cervical spine. A clinical course of the traumatic process and biomechanical musculoligamentous alterations, development and severity of mental disorders were established. These characteristics should be taken into consideration in forensic medical evaluation of health deterioration. 相似文献
960.
A complex investigation of catalase activity in erythrocytes was conducted basing on the results of computer quantitative morphometry of histochemical examination of blood samples from persons with mild craniocerebral trauma. It was found that erythrocytic catalase activity correlates with severity of brain trauma. A novel technique of objective histochemical diagnosis of trauma is described. It provides objective grounds for expert conclusions. Differential features of erythrocytic shape were defined in a small series of micropreparations vs the rest blood samples. 相似文献