全文获取类型
收费全文 | 15071篇 |
免费 | 416篇 |
专业分类
各国政治 | 621篇 |
工人农民 | 564篇 |
世界政治 | 1040篇 |
外交国际关系 | 438篇 |
法律 | 9348篇 |
中国共产党 | 1篇 |
中国政治 | 93篇 |
政治理论 | 3260篇 |
综合类 | 122篇 |
出版年
2020年 | 164篇 |
2019年 | 220篇 |
2018年 | 279篇 |
2017年 | 337篇 |
2016年 | 327篇 |
2015年 | 249篇 |
2014年 | 268篇 |
2013年 | 1413篇 |
2012年 | 338篇 |
2011年 | 382篇 |
2010年 | 303篇 |
2009年 | 361篇 |
2008年 | 396篇 |
2007年 | 387篇 |
2006年 | 372篇 |
2005年 | 355篇 |
2004年 | 350篇 |
2003年 | 358篇 |
2002年 | 339篇 |
2001年 | 584篇 |
2000年 | 519篇 |
1999年 | 410篇 |
1998年 | 222篇 |
1997年 | 172篇 |
1996年 | 180篇 |
1995年 | 186篇 |
1994年 | 184篇 |
1993年 | 179篇 |
1992年 | 317篇 |
1991年 | 329篇 |
1990年 | 329篇 |
1989年 | 325篇 |
1988年 | 298篇 |
1987年 | 303篇 |
1986年 | 356篇 |
1985年 | 350篇 |
1984年 | 296篇 |
1983年 | 288篇 |
1982年 | 199篇 |
1981年 | 177篇 |
1980年 | 158篇 |
1979年 | 192篇 |
1978年 | 139篇 |
1977年 | 138篇 |
1976年 | 130篇 |
1975年 | 112篇 |
1974年 | 146篇 |
1973年 | 136篇 |
1972年 | 116篇 |
1969年 | 98篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
871.
872.
873.
874.
875.
The use of a new technique, Fourier transform infrared (FTIR) chemical imaging, has been demonstrated for the enhancement of latent fingermarks on a number of surfaces. Images of untreated fingermarks on glass backgrounds with excellent ridge detail were acquired using infrared chemical imaging. High quality fingermarks on glass backgrounds were also developed using ethyl cyanoacrylate (super glue) fuming and subsequent infrared chemical imaging. This new method allows the collection of images from backgrounds that traditionally pose problems for current fingermark detection methods. The background may, for example, be highly colored, have a complex pattern, or possess other pattern or image characteristics that make it difficult to separate fingermark ridges using traditional optical or luminescent visualization. One background that has proven to be a challenging surface for the development of latent fingermarks is the Australian polymer banknote. To demonstrate the power and applicability of infrared chemical imaging, fingermarks fumed with ethyl cyanoacrylate were successfully imaged from Australian polymer banknotes. 相似文献
876.
Sexually dimorphic distinctions within the human thoracic area may include morphological as well as metric differences in the sternum and 4th rib. This research assesses the validity of a set of previously published measurements from chest radiographs and their use in contemporary forensic situations. The chest plates from 130 adult individuals of a known sample undergoing medico-legal post-mortem examination were examined at autopsy. Thoracic radiographs were taken using a Faxitron cabinet X-ray machine at 40 kV using Kodak Diagnostic Film Ready Pack X-Omat TL. Measurements were taken to the nearest millimetre using a sliding calliper. Logistic regression analysis of measurements of the sternum and 4th rib was undertaken to determine sex. Using 4th rib width and sternal area, sex was predicted at an accuracy of 95.8% for males and 90.3% for females. 相似文献
877.
Ehlers-Danlos Syndrome Type IV is an illness that often leads to premature death due to arterial rupture or dissection and is characterized by very fragile connective tissue. This report documents the death of a 30-year-old man with Ehlers-Danlos Syndrome Type IV from myocardial rupture and cardiac tamponade following a myocardial infarction. We believe that Ehlers-Danlos Syndrome Type IV contributed to the coronary atherosclerosis and myocardial rupture in this young man and that this disease led indirectly to his death by myocardial infarction, an unusual cause of death in this syndrome. 相似文献
878.
Latkoczy C Becker S Dücking M Günther D Hoogewerff JA Almirall JR Buscaglia J Dobney A Koons RD Montero S van der Peijl GJ Stoecklein WR Trejos T Watling JR Zdanowicz VS 《Journal of forensic sciences》2005,50(6):1327-1341
Forensic analysis of glass samples was performed in different laboratories within the NITE-CRIME (Natural Isotopes and Trace Elements in Criminalistics and Environmental Forensics) European Network, using a variety of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) systems. The main objective of the interlaboratory tests was to cross-validate the different combinations of laser ablation systems with different ICP-MS instruments. A first study using widely available samples, such as the NIST SRM 610 and NIST SRM 612 reference glasses, led to deviations in the determined concentrations for trace elements amongst the laboratories up to 60%. Extensive discussion among the laboratories and the production of new glass reference standards (FGS 1 and FGS 2) established an improved analytical protocol, which was tested on a well-characterized float glass sample (FG 10-1 from the BKA Wiesbaden collection). Subsequently, interlaboratory tests produced improved results for nearly all elements with a deviation of < 10%, demonstrating that LA-ICP-MS can deliver absolute quantitative measurements on major, minor and trace elements in float glass samples for forensic and other purposes. 相似文献
879.
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
880.
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