全文获取类型
收费全文 | 17542篇 |
免费 | 1293篇 |
专业分类
各国政治 | 728篇 |
工人农民 | 573篇 |
世界政治 | 1330篇 |
外交国际关系 | 510篇 |
法律 | 12225篇 |
中国共产党 | 1篇 |
中国政治 | 119篇 |
政治理论 | 3214篇 |
综合类 | 135篇 |
出版年
2020年 | 392篇 |
2019年 | 414篇 |
2018年 | 505篇 |
2017年 | 545篇 |
2016年 | 563篇 |
2015年 | 508篇 |
2014年 | 505篇 |
2013年 | 1825篇 |
2012年 | 390篇 |
2011年 | 493篇 |
2010年 | 640篇 |
2009年 | 606篇 |
2008年 | 419篇 |
2007年 | 392篇 |
2006年 | 517篇 |
2005年 | 378篇 |
2004年 | 362篇 |
2003年 | 366篇 |
2002年 | 331篇 |
2001年 | 610篇 |
2000年 | 489篇 |
1999年 | 425篇 |
1998年 | 236篇 |
1997年 | 213篇 |
1996年 | 168篇 |
1995年 | 195篇 |
1994年 | 209篇 |
1993年 | 192篇 |
1992年 | 311篇 |
1991年 | 366篇 |
1990年 | 320篇 |
1989年 | 346篇 |
1988年 | 320篇 |
1987年 | 305篇 |
1986年 | 319篇 |
1985年 | 353篇 |
1984年 | 338篇 |
1983年 | 312篇 |
1982年 | 239篇 |
1981年 | 218篇 |
1980年 | 207篇 |
1979年 | 231篇 |
1978年 | 159篇 |
1977年 | 128篇 |
1976年 | 128篇 |
1975年 | 126篇 |
1974年 | 140篇 |
1973年 | 127篇 |
1972年 | 107篇 |
1971年 | 96篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
The increasingly global role of a forensic anthropologist necessitates a proper means for archiving evidence for re-examination. Large quantities of evidence can be stored and be made readily accessible through digital imaging. This study focuses on age assessment from digital photographs for personal identity reconstructions. A comparison of 52 Suchey-Brooks scores assigned to digital images and actual bone revealed that age assessment from digital images can be completed with accuracy. Coefficients of concordance imply that there significant agreement between osteological assessment of aging criteria from digital images and direct observation-greater than random change alone (p < 0.05). However, assessments from images should be approached with caution since there are inherent limitations of the naked eye in identifying morphological changes in certain skeletal features, especially where older adults are concerned. Although there is no replacement for a hands-on physical assessment, a digital archive may facilitate the global needs of the forensic anthropologist. 相似文献
942.
Dried, treated wood was sealed with Thompson's WaterSeal "Clear Multi-Surface Waterproofer" and exposed to outdoor, summer conditions. Sections of the sealed wood were then periodically tested and analyzed in accordance with ASTM methods. The WaterSeal contained a medium petroleum distillate (MPD) as a solvent for a wax. The treated lumber contained a background of aldehydes that could mimic a dearomatized MPD if not carefully investigated by the analyst. The MPD of the WaterSeal was detectable 14 days, but not 27 days after application with exposure to relatively hot, dry and sunny weather conditions. The test was repeated with the MPD detectable 16 days, but not 20 days after application with exposure to cooler and wetter weather conditions. The testing demonstrates the need for a thorough and complete investigation by the fire investigator and the submission of comparison samples to the laboratory. 相似文献
943.
944.
945.
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
946.
Traditionally, toolmark test exemplars are produced by applying a tool's working surface to a piece of soft metal such as lead. Soft, pliable metals are primarily used for this purpose because they will replicate the microscopic grooves present on a tool's working surface without damaging the tool. In this paper the authors present an alternative material for the preparation of test toolmarks. Jewelry modeling or carving waxes are utilized in this study. These waxes are designed for the jewelry modeling industry to create very fine, highly detailed wax models of jewelry pieces that will be cast in various metals utilizing the lost wax casting method. Jeweler's waxes have been found to be ideal for preparing test toolmarks from exemplar tools. The test tool's working surface is applied to a piece of the appropriate wax in a manner consistent with the tool's design. The replicas obtained are exact, highly detailed, 1:1, negative impressions of the exemplar tools working surface, have a long shelf-life, and are suitable for use in toolmark examination and comparison cases. 相似文献
947.
Schubert GD 《Journal of forensic sciences》2005,50(6):1411-1416
Many automobile manufacturers began installing airbags on the driver's side in the late 1980's. Passenger side airbags followed in the early 1990's. Most airbags use a solid-propellant type of material that produces a hot gas to inflate the airbags. The gas in the driver side airbag leaves the inflator at a temperature as hot as 600 degrees C. The hot gas escapes through the vent holes after deployment, but it can also leak through the stitching seams in the front and singe a pattern on the occupant's clothing characteristic of the seam pattern. The singe patterns from the driver and passenger side airbags will be different. Cornstarch, which is used as a lubricant in some driver side airbags, can transfer to the driver's shirt. Hairs, fibers and make-up can transfer from the driver or passenger to the surface of the deployed airbags. Two cases are presented, illustrating singe patterns and particle transfers, and how they helped determine who a driver or passenger were. 相似文献
948.
The forensic pathologist increasingly relies on the forensic anthropologist to be the consulting expert in human identification. Likewise, if identification is not possible from visual inspection of skeletal remains, the forensic biologist may be called upon to conduct DNA analysis. The possibility of downstream DNA testing needs to be considered when skeletal preparation techniques are employed to deflesh human remains, as they have the potential to strongly impact genetic analyses and subsequent identification. In this study, three cleaning techniques, boiling bone in water, in bleach, and in powdered detergent/sodium carbonate, were tested for their effect on nuclear and mtDNA recovery from a variety of human and non-human bones. A statistically significant reduction in DNA yields occurred in non-human bones cleaned with bleach, and DNA degradation was apparent electrophoretically. The human bones also showed much lower yields from bleach cleaning, while the detergent/carbonate method allowed the largest segments of DNA to be amplified, indicating it may have a less degradative effect on bone DNA than either of the other cleaning processes. 相似文献
949.
The technique is proposed allowing quantitation of brain edema and typing of liquor distribution in different parts of brain tissue. In combination with other assays this test can determine a variant of tanatogenesis, detect cause of death and duration of the terminal period. The method application is illustrated by the study of brain hydration in mechanical strangulation asphyxia. It is shown that this death is associated with hypohydration of cerebral structures, especially pronounced in the cortical compartments. 相似文献
950.