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   1085篇
  免费   24篇
各国政治   48篇
工人农民   46篇
世界政治   60篇
外交国际关系   25篇
法律   796篇
中国政治   21篇
政治理论   106篇
综合类   7篇
  2023年   4篇
  2022年   5篇
  2021年   9篇
  2020年   18篇
  2019年   25篇
  2018年   24篇
  2017年   23篇
  2016年   32篇
  2015年   18篇
  2014年   17篇
  2013年   75篇
  2012年   30篇
  2011年   29篇
  2010年   23篇
  2009年   19篇
  2008年   28篇
  2007年   18篇
  2006年   15篇
  2005年   30篇
  2004年   42篇
  2003年   37篇
  2002年   25篇
  2001年   101篇
  2000年   67篇
  1999年   73篇
  1998年   35篇
  1997年   4篇
  1996年   3篇
  1995年   8篇
  1994年   4篇
  1993年   7篇
  1992年   21篇
  1991年   18篇
  1990年   39篇
  1989年   26篇
  1988年   29篇
  1987年   23篇
  1986年   14篇
  1985年   13篇
  1984年   8篇
  1983年   8篇
  1982年   11篇
  1981年   8篇
  1980年   4篇
  1979年   11篇
  1978年   7篇
  1973年   2篇
  1971年   4篇
  1970年   3篇
  1968年   2篇
排序方式: 共有1109条查询结果,搜索用时 406 毫秒
141.
Image fusion is a process of combining two or more images into an image. It can extract features from source images, and provide more information than one image can. Multi-resolution analysis plays an important role in image processing, it provides a technique to decompose an image and extract information from coarse to fine scales. In some practical forensic examinations (such as the cartridge image check), we cannot obtain all information from just one image; on the contrary, we need information from images with difference light sources (or light ways). In this paper, we apply an image fusion method based on multi-resolution analysis to forensic science. Synthetic and real images (such as images from closed-up photography and flash photography) are used to show the capability of the multi-resolution image fusion technique.  相似文献   
142.
Cannabinoid use was studied in a nonspecific population of postmortem urine specimens in the State of Maryland. Of 500 sequential specimens screened for cannabinoids by enzyme multiplied immunoassay EMIT, 63 (13%) were initially positive and 58 (12%) were confirmed positive (92%). It was observed that geographic location and race did not correlate with cannabinoid prevalence. Cannabinoid use was observed to be strongly age related, with peak use by the 21- to 25-year-old age group where 22% of the cases were positive. Use of cannabinoids was also closely linked to homicides, which represented nearly half of the positive cases but only 13% of the total cases. When comparing manner of death, the greatest percent of confirmed positives was seen in homicide (26%) and drug-related (17%) deaths. The incidence of cannabinoid use was found to be more than 3 times as great in drug-related (17%) as compared to natural deaths (5%). The percent of cannabinoid-positive cases from vehicle-related accidents was low (6%) and that from nonvehicle-related accidents somewhat higher (10%). Other drugs appeared in cannabinoid-positive cases. Most prevalent was ethanol N = 18, followed by morphine (from heroin, N = 11), quinine N = 11, and cocaine N = 11. Phencyclidine (PCP) occurred twice and several other drugs were reported only once. Of the 25 homicide cases screened for drugs, 64% were positive for some drug including ethyl alcohol. Thus it appears that a high percentage of homicide cases are drug related. Males greatly outnumbered females (56:2) in positive cases, but the number of female specimens received was small.  相似文献   
143.
Mechanical forces applied to the neck region are known to release certain amounts of thyroglobulin into circulation. In this experiment, an attempt was made to detect thyroglobulin in bloodstains as an aid in the diagnosis of mechanical asphyxia. Experimental bloodstains containing thyroglobulin at concentrations of 1, 2, 5 and 10 mu g/mL were prepared on a sheet of filter paper. Small pieces of bloodstains, measuring approximately 2.4 cm2 in area, were extracted with 0.1 mL of distilled water and the extracts were tested against an antihuman thyroglobulin serum by precipitation-electrophoresis. Bloodstains containing more than 1 mu g/mL of thyroglobulin formed distinct precipitin lines for up to one month of storage, while bloodstains containing more than 5 mu g/mL of thyroglobulin formed distinct precipitin lines for up to three months of storage. The present results suggest that the bloodstains can be utilized in the diagnosis of mechanical asphyxia.  相似文献   
144.
Blood cyanide concentration was determined in rabbits intoxicated orally or by inhalation. Experiments were carried out under urethane anaesthesia. In the inhalation experiments, rabbits inhaled a combustion product containing HCN via the tracheal cannula and in the oral studies animals were administered NaCN solution into the stomach. In addition to the carotid artery and jugular vein blood samples, postmortem samples were obtained from both sides of the heart and the descending vena cava. The arterial cyanide concentration in the inhalation group showed a close relationship with ventilation. After an initial rise, blood levels decreased a little, in some cases with transient apnea. At the last stage it again increased with gasping, reaching its maximal value. After ultimate apnea, the blood cyanide concentration declined. The blood cyanide values were higher in the oral group than in the inhalation group. The difference between the two groups became larger in the inferior order, the left heart blood--the right heart blood--blood in the descending vena cava. The left heart/right heart ratio of the inhalation group was significantly higher than that of the oral group (1.28+/- 0.28 vs. 0.95+/- 0.09). The coefficient of variation (c.v.) of the inhalation group was larger than that of the other group. Within the inhalation group, the left heart blood showed the largest c.v. values and this was probably due to redistribution of the cyanide by bloodstream after attainment of the maximal concentration.  相似文献   
145.
A sensitive enzyme-linked immunosorbent assay (ELISA) for detection of ABO blood substances in human body fluids was devised. The ELISA plates coated with purified human anti-A or anti-B serum effectively captured the blood substances, and these were then analysed by the combination of rabbit anti-A and goat anti-B. This capture ELISA could differentiate the type AB specimen from a mixture of the type A and the type B specimens, and the method was applied to rape cases to make the ABO typing of the criminal.  相似文献   
146.
Forty-six cases of child abuse/neglect autopsied during the period of 1967 to 1990 were investigated. The weight and histological findings of the thymus were compared with those of control children. In most abused and/or neglected children, the weight of the thymus decreased conspicuously. Involution correlated well to the degree and period of maltreatment. In cases without weight loss of the thymus, i.e. spasmodic abuse by a mentally deranged parent or foster parent, a short history of maltreatment was noted. On the other hand, marked involution was observed in cases of prolonged physical abuse and/or neglect. Microscopically, a decrease in the number and pyknosis of lymphocytes were observed in the involuted thymus. Atrophy of the thymus was more conspicuous in the cortex than in medulla. Immunohistochemically, CD-1a positive cells (immature thymocytes) decreased in cases with thymic involution. This involution appears to be an important index of the degree and duration of child abuse/neglect. Furthermore, thymic involution in the early stage of childhood may also be related to insufficiency of the immune system.  相似文献   
147.
A simple isoelectric focusing method for haptoglobin (HP) typing is described. Serum was pretreated first with C. perfringens neuraminidase (CPN) and then with dithiothreitol (DTT). The treated serum was subjected to polyacrylamide gel isoelectric focusing (PAGIF), and the band patterns were detected by immunoblotting. The method could be successfully applied to HP typing of bloodstains as old as 2 months. A slight modification of it enabled HP, complement component C81, and factor I (IF) to be typed simultaneously. The immunoblotting facilitated preservation of HP patterns. Thus, the PAGIF method for HP typing is suitable for routine use in the forensic laboratory.  相似文献   
148.
A high selective screening test (Ad-Tip method) for methamphetamine in human urine has been devised. The method involves a brief extraction from a urine sample with an Ad-Tip (ODS-silica minicolumn), washing, eluting with modified Simon's reagent, and coloration with carbonate buffer. Detection limit of methamphetamine in urine is 1 microgram/ml and the test takes within 3 min/sample. The results of the Ad-Tip method were almost identical to those of laboratory analyses.  相似文献   
149.
150.
The distribution of the human red cell phosphoglucomutase (PGM1) subtypes in samples from Japanese population (n = 277) living in the Miyagi Prefecture, the northern part of Japan, was investigated by applying the thinlayer polyacrylamide gel isoelectric focusing. In our population sample all the ten common phenotypes were demonstrated, and the estimated allele frequencies for the genes PGM1+1, PGM1-1, PGM2+1, and PGM2-1 were 0.671, 0.107, 0.161, and 0.061, respectively. Family studies (n = 40) indicated an autosomal codominant inheritance and confirmed the four alleles. The new system will increase the probability of exclusion in paternity cases among Japanese to 29.4% compared with 14.3% if the two allele system is used.  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