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   5798篇
  免费   51篇
各国政治   177篇
工人农民   61篇
世界政治   793篇
外交国际关系   495篇
法律   3543篇
中国共产党   83篇
中国政治   253篇
政治理论   359篇
综合类   85篇
  2021年   27篇
  2018年   22篇
  2016年   21篇
  2015年   23篇
  2014年   112篇
  2013年   30篇
  2012年   414篇
  2011年   387篇
  2010年   141篇
  2009年   111篇
  2008年   331篇
  2007年   427篇
  2006年   425篇
  2005年   376篇
  2004年   331篇
  2003年   338篇
  2002年   319篇
  2001年   243篇
  2000年   269篇
  1999年   124篇
  1998年   70篇
  1997年   41篇
  1996年   45篇
  1995年   32篇
  1994年   81篇
  1993年   44篇
  1992年   51篇
  1991年   55篇
  1990年   34篇
  1989年   33篇
  1988年   123篇
  1987年   34篇
  1986年   39篇
  1985年   38篇
  1984年   46篇
  1983年   43篇
  1982年   28篇
  1981年   41篇
  1980年   51篇
  1979年   42篇
  1978年   21篇
  1977年   57篇
  1976年   38篇
  1973年   18篇
  1964年   28篇
  1963年   25篇
  1962年   41篇
  1961年   19篇
  1960年   23篇
  1959年   30篇
排序方式: 共有5849条查询结果,搜索用时 8 毫秒
181.
The article reports on the injury pattern seen in fatally wounded car passengers after rear-end collisions on motorways. The study material included 5 rear-end collisions, in which 9 car occupants (5 drivers and 4 front-seat passengers) were killed. The change in velocity (delta v) was above 60 km/h in all the reported cases. The injury pattern showed the following characteristics: extensive soft-tissue traumatization (subcutaneous haematomas, blood-filled pockets, "décollements") not discernible from outside on the back of the trunk, mostly in the lumbosacral region; dorsal serial rib fractures, often combined with fractures of the spine (including the sacrum and the coccyx) and/or the pelvis; ruptures of the aorta at the typical sites of predisposition; ruptures of the liver and spleen (particularly at the visceral surfaces).  相似文献   
182.
With increasing frequency, relatively small, fragmentary evidence thought to be osseous or dental tissue of human origin is submitted to the forensic laboratory for DNA analysis with the request for positive identification. Prior to performing DNA analysis, however, it is prudent to first perform a presumptive test or "screen" to determine whether the questioned material may be eliminated from further consideration. When material is shown not to be consistent with bone/teeth, DNA testing is not performed. When such determinations cannot be made from gross morphological features, elemental analysis can be indicative. This presumptive test is made possible by applying scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) in conjunction with an X-ray spectral database recently developed by the FBI laboratory. This database includes spectra for many different materials including known examples of bone and tooth from many different contexts and representing the full range of taphonomic conditions. Results of SEM/EDS analysis of evidence can be compared to these standards to determine if they are consistent with bone and/or tooth and, if not, then what the material might represent. Analysis suggests that although the proportions and amounts of calcium and phosphorus are particularly important in differentiating bone and tooth from other materials, other minor differences in spectral profile can also provide significant discrimination. Analysis enables bone and tooth to be successfully distinguished from other materials in most cases. Exceptions appear to be ivory, mineral apatite, and perhaps some types of corals.  相似文献   
183.
Laser desorption mass spectrometry (LDMS) may be used for the detection and identification of dyes found in inks. Naturally-aged and artificially-aged blue and black ballpoint pen inks containing the cationic dye methyl violet were analyzed on paper. The average molecular weight of the dye sample was calculated from LD mass spectral data and plotted versus time. The resulting aging curves demonstrate that, as dye degradation increases, the average molecular weight of the dye decreases. Typical variables involved in ink aging, such as the type of paper and ink formulation, were investigated. Results show that these variables influence the rate of dye degradation. Furthermore, UV accelerated aging has been developed and tested as an alternative to thermal approaches.  相似文献   
184.
This Article addresses the problems with our nation's cultural and legal prohibitions against certain pain management treatments. The practice of pain management has not kept pace with the many medical advances that have made it possible for physicians to ameliorate most pain. The Author notes that some patients are denied access to certain forms of treatments due to the mistaken belief that addiction may ensue. Additionally, some individuals are under-treated for their pain to a greater degree than are others. This is especially the case for our nation's prisoners. The Author contends that prisoners are frequently denied effective pain amelioration. He notes, however, that there has been improvement in medical treatment in general for prisoners due to court challenges based on the Eighth Amendment's prohibition against cruel and unusual punishment. Yet, due to the protection of qualified immunity given to jailers and prison health care providers, prisoners cannot bring a claim for negligence or medical malpractice, they must allege a violation of their constitutional rights, a significantly higher legal standard. Prisoners must meet a subjective test showing that there was a deliberate indifference to their medical needs that violates the protection of the Eighth Amendment. The Author concludes that because medical advances have made it possible to alleviate most pain suffering, withholding pain treatment or providing a less effective treatment is tantamount to inflicting pain and should be viewed as a violation of the Eighth Amendment.  相似文献   
185.
A non-destructive method for discriminating between different types of paper has been proposed, using image analysis, Fourier transformation, and cross-correlation matching. A fast Fourier transform (FFT) is used to extract the periodicity in the structure of paper that results from the manufacturing processes. The light-transmission images of the paper to be Fourier transformed are obtained from a flatbed image scanner. The similarity between the power spectrum of the FFT of the sample and that of a reference is quantified using a cross-correlation matching method. An advantage of using frequency analysis is that periodicity can be detected even if the sample is damaged or is printed on. The technique works on samples as small as 2 cm2.  相似文献   
186.
187.
188.
189.
190.
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