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   18455篇
  免费   548篇
各国政治   621篇
工人农民   1368篇
世界政治   977篇
外交国际关系   581篇
法律   11575篇
中国共产党   1篇
中国政治   54篇
政治理论   3785篇
综合类   41篇
  2021年   60篇
  2020年   193篇
  2019年   232篇
  2018年   1480篇
  2017年   1455篇
  2016年   1292篇
  2015年   303篇
  2014年   282篇
  2013年   997篇
  2012年   412篇
  2011年   1173篇
  2010年   1256篇
  2009年   862篇
  2008年   997篇
  2007年   923篇
  2006年   275篇
  2005年   305篇
  2004年   414篇
  2003年   373篇
  2002年   261篇
  2001年   465篇
  2000年   424篇
  1999年   293篇
  1998年   190篇
  1997年   158篇
  1996年   142篇
  1995年   144篇
  1994年   167篇
  1993年   132篇
  1992年   196篇
  1991年   218篇
  1990年   203篇
  1989年   212篇
  1988年   205篇
  1987年   191篇
  1986年   232篇
  1985年   207篇
  1984年   167篇
  1983年   177篇
  1982年   118篇
  1981年   120篇
  1980年   85篇
  1979年   136篇
  1978年   81篇
  1977年   82篇
  1976年   69篇
  1974年   73篇
  1973年   66篇
  1972年   67篇
  1970年   46篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
State Supreme Courts require a minimum threshold of reliability and acceptance in the scientific community for all medical and similar evidence to be admitted at trial. In Florida and some other states, the courts adhere to what is known as the Frye standard, whereas in most states and in Federal Courts, it is the so-called Daubert standard. The jurisdiction of the present case is Hillsborough County (Tampa), Florida. Forensic pathologists seldom, if ever, are requested to participate in such hearings, unlike their toxicological and basic science colleagues who are more involved in research methodology and technical procedures. The burden is on the proponent of the evidence to prove the general acceptance of both the underlying scientific principle of the test and procedures used to apply that principle to the facts of the case at hand. The trial judge has the sole discretion to determine this question and general acceptance must be established by a preponderance of the evidence. The authors describe in detail a hearing in a case in which they were all involved. One author (WQS) had researched and documented the original scientific methodology in the literature. The situation involved a car and tractor trailer crash with the two occupants of the car dying of multiple trauma, whereas the truck driver was not injured. Autopsy of the auto driver revealed multiple injuries with exsanguination, and only vitreous humor and liver tissue, but not blood, were tested for ethyl alcohol. The estate of the driver of the automobile brought suit against the owner of the trucking company for wrongful death. The plaintiff requested a Frye hearing to question the reliability of testing other body specimens to translate to probable blood alcohol level. The testimony, submitted documents, and eventual decision by the judge are discussed.  相似文献   
962.
One hundred thirty-four unrelated Northeast Brazilian individuals were typed for the HPRTB, F13B, and LPL short tandem repeats (STRs). DNA was amplified by specific primers and identified by silver staining of polyacrylamide gels. The allelic frequencies of these loci were in agreement with Hardy-Weinberg proportions. The most frequent alleles were HPRTB*13, F13B*10, LPL*10. The combined probability of paternity and the discrimination power of these 3 STRs were high, permitting their utilization for forensic science purposes.  相似文献   
963.
An accurate and simple method was developed to determine the level of toluene in urine and blood quantitatively by using the gas chromatography/mass spectrometry (GC/MS) with headspace--solid phase microextraction (HS-SPME) technique. An assembly of SPME with a replaceable extraction fiber, coated with 100 microm polydimethylsiloxane, was used. The detection limit of toluene in blood and urine with HS-SPME technique was 10 times higher than that with headspace (HS) technique. To compare the HS-SPME with HS technique for the determination of toluene in biological fluids, blood and urine samples from glue sniffers were analyzed by both methods. The level of toluene by the two techniques was highly correlated: the correlation coefficient (r2) between the two sets of values were 0.98 and 0.96 in urine and blood, respectively.  相似文献   
964.
A technique that exposes fingerprint residue to a gaseous electrical discharge in nitrogen followed by treatment with ammonium hydrogen carbonate vapors to produce fluorescence is investigated. Particular attention is made to fluorescence observed via laser illumination at 514 nm. Insight into the nature of the fluorescent components is achieved through the use of thin-layer chromatography (TLC) of fingerprint residue. Results reported indicate the fluorescence observed is from previously non-fluorescent fractions of the fingerprint residue, and TLC results point towards lipid derivatives as a possible source of the fluorescence.  相似文献   
965.
During STR analysis on the 310 Genetic Analyzer, retarded migration of GS500ROX size standards and alleles in some samples was observed. The contribution of reagents, capillary and performance optimized polymer POP 4 to the observed anomaly was experimentally eliminated. Variation in electrophoresis temperature between 55 degrees C and 65 degrees C did not alter the rate of migration of GX500ROX size standard and sample alleles. An eroded connector for the cathode mounted on the heat plate assembly caused the abnormal migration. Hence, it is important to verify the mobility of all fragments in the size standard for each sample to avoid any erroneous allele calls by the automated data analysis software.  相似文献   
966.
Short tandem repeat (STR) markers are commonly used in basic genetic research and in human identification testing. Clinically, STRs can be used to study genetic alterations in tumors. A genetic deletion common to many types of cancer is referred to as the loss of heterozygosity (LOH). Numerous examples of LOH in cancer have been described and some have been mapped to areas located in close proximity to markers employed in human identity testing. Despite this fact, LOH has rarely been observed for STR loci commonly employed in forensic testing. Recently, for medico-legal purposes, we were asked to determine whether a tissue biopsy originated from a particular individual. For a reference source we assessed two specimens, one from normal tissue and one from cancerous tissue. When both reference specimens were used to generate DNA profiles, we observed LOH at one STR locus, D13S317. As demonstrated in other cancers only the cancerous biopsy demonstrated LOH. The forensic community should be cognizant of these unusual circumstances because, as identification of human DNA continues to be used more extensively, certain instances will arise in which reference material will not be readily available. In these situations, archived specimens may be employed as a reference source. Clinical specimens such as tissue biopsies should be used with caution if they have not been confirmed to contain normal tissue.  相似文献   
967.
Allele frequencies for six DNA polymorphisms have been studied in a population sample from Cantabria (middle north Spain) using the polymerase chain reaction. The HLA-DQA1 locus was analyzed by the reverse dot-blot technique and the other five by polyacrylamide gel electrophoresis followed by silver staining. Six alleles were found for HLA-DQA1. 15 alleles for D1S80, 6 alleles for HUMTHO1 and HUMCSF1PO, 7 for HUMTPOX and 8 alleles for HUMVWA. The 21 repeat allele in HUMVWA had not previously been reported in a Spanish population. The genotype distributions met Hardy-Weinberg expectations for all the systems and some statistical parameters of forensic interest were calculated. Comparisons with other populations revealed significant differences for HLA-DQA1, HUMVWA and HUMTHO1, with interracial differences being more pronounced than between Spanish populations. The HUMVWA system showed the highest forensic efficiency of the six polymorphisms studied.  相似文献   
968.
This report contains the results of two population studies on the X chromosome STR HumHPRTB carried out in a Northern and a Southern region of Germany. The numbers of unrelated individuals were 443 and 335, respectively. Eight alleles (alleles 9 to 16) were found. In female individuals 29 different genotypes were encountered. In German populations the HumHPRTB STR was characterized by the following data: PIC = 0.750; HET = 0.769: MEC = 0.556. Allele distribution met the Hardy-Weinberg expectations. The Northern and Southern populations did not show any significant differences.  相似文献   
969.
We report a fatal case of death due to unusual aspiration of sardine fry in an elderly Japanese man with lung cancer. The cause of death was sudden respiratory arrest while eating. Autopsy revealed peculiar materials with cell nests and pigmented particles, together with striated muscle and skin, in the ectatic bronchioles of the left lower lobe. Serial histologic sections suggested that the structures observed were the eyeballs of small animals that appeared to have been inhaled. The patient had habitually eaten sardine fry and rice gruel, which were also detected in the gastric contents. Therefore, the eyes were considered to be those of the fry, which is a popular food item in Japan. This was confirmed by histologic examination of fry that were obtained commercially.  相似文献   
970.
Drug abuse and its consequences are everyday problems encountered globally, and Scotland is no exception. During a study of drug-related deaths in the Strathclyde region of Scotland it was noted that known drug users who had recently been released from prison were at high risk of dying from a drug overdose. The majority of deaths occurred within one week of the release date and polydrug use was prevalent. Morphine was the most frequently encountered drug and this was found in combination with benzodiazepines in a significant number of cases. This paper highlights the dangers of resuming drug consumption following a period of abstinence.  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