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   1499篇
  免费   511篇
各国政治   105篇
工人农民   5篇
世界政治   19篇
外交国际关系   70篇
法律   1229篇
中国共产党   2篇
中国政治   13篇
政治理论   522篇
综合类   45篇
  2022年   6篇
  2021年   44篇
  2020年   48篇
  2019年   167篇
  2018年   137篇
  2017年   117篇
  2016年   146篇
  2015年   130篇
  2014年   131篇
  2013年   304篇
  2012年   202篇
  2011年   142篇
  2010年   89篇
  2009年   45篇
  2008年   79篇
  2007年   65篇
  2006年   60篇
  2005年   21篇
  2004年   20篇
  2003年   34篇
  2002年   11篇
  2001年   7篇
  2000年   1篇
  1999年   3篇
  1983年   1篇
排序方式: 共有2010条查询结果,搜索用时 31 毫秒
961.
Biological fluid identification is an important facet of evidence examination in forensic laboratories worldwide. While identifying bodily fluids may provide insight into which downstream DNA methods to employ, these screening techniques consume a vital portion of the available evidence, are usually qualitative, and rely on visual interpretation. In contrast, qPCR yields information regarding the amount and proportion of amplifiable genetic material. In this study, dilution series of either semen or male saliva were prepared in either buffer or female blood. The samples were subjected to both lateral flow immunochromatographic test strips and qPCR analysis. Analytical figures of merit—including sensitivity, minimum distinguishable signal (MDS) and limit of detection (LOD)—were calculated and compared between methods. By applying the theory of the propagation of random errors, LODs were determined to be 0.05 μL of saliva for the RSID? Saliva cards, 0.03 μL of saliva for Quantifiler® Duo, and 0.001 μL of semen for Quantifiler® Duo. In conclusion, quantitative PCR was deemed a viable and effective screening method for subsequent DNA profiling due to its stability in different matrices, sensitivity, and low limits of detection.  相似文献   
962.
Manual localization of bone fragments on the ground or on complex surfaces in relation to accidents or criminal activity may be time‐consuming and challenging. It is here investigated whether combining a near‐infrared hyperspectral camera and chemometric modeling with false color back‐projection can be used for rapid localization of bone fragments. The approach is noninvasive and highlights the spatial distribution of various compounds/properties to facilitate manual inspection of surfaces. Discriminant partial least squares regression is used to classify between bone and nonbone spectra from the hyperspectral camera. A predictive model (>95% prediction ability) is constructed from raw chicken bones mixed with stone, sand, leaves, moss, and wood. The model uses features in the near‐infrared spectrum which may be selective for bones in general and is able to identify a wide variety of bones from different animals and contexts, including aged and weathered bone.  相似文献   
963.
The U.S. agricultural sector is vulnerable to intentionally introduced microbial threats because of its wide and open distribution and economic importance. To investigate such events, forensically valid assays for plant pathogen detection are needed. In this work, real‐time PCR assays were developed for three model plant pathogens: Pseudomonas syringae pathovar tomato, Xylella fastidiosa, and Wheat streak mosaic virus. Validation included determination of the linearity and range, limit of detection, sensitivity, specificity, and exclusivity of each assay. Additionally, positive control plasmids, distinguishable from native signature by restriction enzyme digestion, were developed to support forensic application of the assays. Each assay displayed linear amplification of target nucleic acid, detected 100 fg or less of target nucleic acid, and was specific to its target pathogen. Results obtained with these model pathogens provide the framework for development and validation of similar assays for other plant pathogens of high consequence.  相似文献   
964.
This paper describes a computerized clavicle identification system primarily designed to resolve the identities of unaccounted‐for U.S. soldiers who fought in the Korean War. Elliptical Fourier analysis is used to quantify the clavicle outline shape from skeletons and postero‐anterior antemortem chest radiographs to rank individuals in terms of metric distance. Similar to leading fingerprint identification systems, shortlists of the top matching candidates are extracted for subsequent human visual assessment. Two independent tests of the computerized system using 17 field‐recovered skeletons and 409 chest radiographs demonstrate that true‐positive matches are captured within the top 5% of the sample 75% of the time. These results are outstanding given the eroded state of some field‐recovered skeletons and the faintness of the 1950's photofluorographs. These methods enhance the capability to resolve several hundred cold cases for which little circumstantial information exists and current DNA and dental record technologies cannot be applied.  相似文献   
965.
This study utilizes an innovative 3D approach to discover metric variables that obtain the highest classification rates for sex estimation from the cranium. Models were constructed from 222 cranial CT scans of U.S. Whites from the Bass Donated Collection. These models were used to create a statistical bone atlas that captures the primary shape variation in the skull and facilitates rapid computer‐automated analyses. The bone atlas showed that important size‐related sex variables are bizygomatic breadth, maximum cranial length, cranial base length, and mastoid height. Shape‐related variables capture sex differences in the projection of the glabellar region, inclination of the frontal, and cranial base flexion. In addition, vault thickness is highly dimorphic, with females having on average thicker vaults in the frontal region, and males having thicker vaults in the occipital region. Cross‐validated linear discriminant analysis obtained >95% accuracy (97.5% with 11 variables and 95.5% with eight variables).  相似文献   
966.
Presumptive tests for blood play a critical role in the examination of physical evidence and in the determination of subsequent analysis. The catalytic power of hemoglobin allows colorimetric reactions employing phenolphthalein (Kastle‐Meyer test) to indicate “whether” blood is present. Consequently, DNA profiles extracted from phenolphthalein‐positive stains are presumed to be from blood on the evidentiary item and can lead to the identification of “whose” blood is present. Crushed nodules from a variety of legumes yielded phenolphthalein false‐positive reactions that were indistinguishable from true bloodstains both in color quality and in developmental time frame. Clothing and other materials stained by nodules also yielded phenolphthalein false‐positive reactivity for several years after nodule exposure. Nodules from leguminous plants contain a protein (leghemoglobin) which is structurally and functionally similar to hemoglobin. Testing of purified leghemoglobin confirmed this protein as a source of phenolphthalein reactivity. A scenario is presented showing how the presence of leghemoglobin from nodule staining can mislead investigators.  相似文献   
967.
In 2006, the Italian National Institute of Statistics (ISTAT) conducted a survey over the entire national territory of women victims of sexual, physical, and psychologic violence, a few years after the first survey, conducted in 2002. For the 2002 survey, respondents were 60,000 women, 22,759 of whom were aged 14–59 years. For the 2006 survey, the sample consisted of 25,000 women aged 16–70 years. Owing to the sensitivity of the issues, the telephone survey technique seems best suited because it provides more anonymity and guarantee of protection. The survey showed that the phenomenon of violence against women is most commonly perpetrated by the partner or ex‐partner, even in cases of homicide. A comparison of the Italian data with those of the U.S.A. for the period 2001–2006 showed a specificity of Intimate Partner Violence in Italy, that seems to be related to cultural elements and psychologic and psychopathologic factors.  相似文献   
968.
In this study, we examined creativity in court‐connected mediation. We analyzed 129 mediated agreements from civil cases in Norway and Denmark and compared the outcomes with the parties' original claims to determine whether the agreement addressed only the disputants' demands or contained other elements. If the mediated agreements contained elements in addition to the original claims, we considered them to be “creative.” We devised a creativity scale and found that approximately two thirds of the cases contained creative elements and one quarter of them contained more than five creative elements. We then sought to determine which aspects of the mediation promoted creativity by looking at a variety of mediation characteristics (length of mediation, characteristics of the parties, etc.). We found that lengthier mediations tended to feature more creativity as did cases that involved two private individuals rather than businesses. Cases whose issues involved inheritance as well as the division of property following divorce seemed to foster the highest levels of creativity. Finally, we found that the amount of money at issue also seemed to be relevant: the highest levels of creativity were found in cases in which more money was at stake. In this article, we also discuss the implications of our findings for future research, practice, and training.  相似文献   
969.
In this research, we explored the contributions of perceived procedural justice (PPJ) to the conflict management behaviors of adolescents when they experience conflict with their teachers. We tested an extensive model to determine how PPJ contributes to conflict management. We also extended research on PPJ to examine its impact on adolescents. Our results, acquired from a large and diverse sample of 256 high school students, indicate that PPJ had an impact on adolescents' approach to managing conflicts with their teachers. Students who perceived that their teachers' decision processes were just were less dominating and more avoiding, obliging, and compromising. In addition, we found that students' perceptions about the legitimacy of their teachers' authority mediated the relationships between PPJ and conflict management style. This study contributes to the rather scarce research on PPJ's role in conflict management and should be useful for educators searching for constructive, relationship‐based tools for conflict management.  相似文献   
970.
Micro‐Raman spectroscopy was applied to forensic identification of pigments in paint chips and provided differentiation between paint samples. Sixty‐six blue automotive paint samples, 26 solid and 40 metallic were examined. It was found that the majority of the collected Raman spectra provided information about the pigments present. However, in some cases, fluorescence precluded pigment identification. Using laser excitation at longer wavelengths or pretreatment to effect photobleaching often resulted in reduced fluorescence, particularly for solid color samples, and allowed pigment identification. The examined samples were compared pairwise taking into account number, location, and intensity of absorption bands in their infrared spectra. The estimated discrimination power ranged from 97% for solid paint samples to 99% for metallic paint samples.  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