全文获取类型
收费全文 | 21052篇 |
免费 | 366篇 |
专业分类
各国政治 | 1002篇 |
工人农民 | 1388篇 |
世界政治 | 1218篇 |
外交国际关系 | 980篇 |
法律 | 11446篇 |
中国共产党 | 1篇 |
中国政治 | 65篇 |
政治理论 | 5156篇 |
综合类 | 162篇 |
出版年
2021年 | 87篇 |
2020年 | 166篇 |
2019年 | 235篇 |
2018年 | 1488篇 |
2017年 | 1468篇 |
2016年 | 1289篇 |
2015年 | 285篇 |
2014年 | 309篇 |
2013年 | 1791篇 |
2012年 | 539篇 |
2011年 | 1225篇 |
2010年 | 1270篇 |
2009年 | 876篇 |
2008年 | 1049篇 |
2007年 | 1039篇 |
2006年 | 376篇 |
2005年 | 424篇 |
2004年 | 536篇 |
2003年 | 501篇 |
2002年 | 404篇 |
2001年 | 424篇 |
2000年 | 396篇 |
1999年 | 316篇 |
1998年 | 179篇 |
1997年 | 205篇 |
1996年 | 184篇 |
1995年 | 193篇 |
1994年 | 204篇 |
1993年 | 157篇 |
1992年 | 237篇 |
1991年 | 255篇 |
1990年 | 216篇 |
1989年 | 233篇 |
1988年 | 209篇 |
1987年 | 205篇 |
1986年 | 234篇 |
1985年 | 187篇 |
1984年 | 181篇 |
1983年 | 197篇 |
1982年 | 128篇 |
1981年 | 129篇 |
1980年 | 94篇 |
1979年 | 151篇 |
1978年 | 101篇 |
1977年 | 102篇 |
1976年 | 86篇 |
1975年 | 79篇 |
1974年 | 96篇 |
1973年 | 90篇 |
1972年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
981.
982.
The suicide rates of the 24 provinces (oblasts) of the Ukraine were found to be strongly associated with indices of social disintegration (such as divorce and illegitimacy rates), with the Western provinces incorporated in the USSR later than other Ukrainian territories having lower suicide rates and lower levels of social disintegration. 相似文献
983.
984.
A consignment of individual packages is thought to contain illegal material, such as drugs, in some or all of the packages. A sample from the consignment is inspected and the quantity of drugs in each package of the sample is measured. It is desired to estimate the total quantity of drugs in the consignment. Sampling variation is present in the original measurements and it is not sufficient just to adjust the sample mean pro rata. An analysis is described which takes account of the uncertainty concerning the proportion of the packages that contain drugs and provides a probabilistic summary of the quantity of drugs in the consignment. In particular, a probabilistic lower bound for the quantity of drugs in the consignment is given, which is dependent on the required standard of proof. This is in contrast to the approach based on confidence intervals which assumes that in the long run, the interval will contain the correct quantity the appropriate proportion of the time, but gives no measure of uncertainty associated with the particular consignment under consideration. 相似文献
985.
Mitochondrial DNA analysis of a maggot crop can identify the corpse a maggot has been feeding on. Analysis of the crop could be useful in a criminal investigation if maggots are found at a suspected crime scene in the absence of a body, or if there is a question of whether a maggot used in postmortem interval estimations moved onto the corpse from another food source. Such analysis can also resolve a chain of custody dispute if it has been suggested that larval samples have been switched. When recovering DNA from a maggot crop, the analyst must be careful to avoid external contamination. We investigated the effects of three simple wash methods developed to reduce external contamination. Maggots raised on pig liver and intentionally contaminated with cow blood were washed using water, 20% bleach, or a solution containing the enzyme DNase. Only washing the maggots in 20% bleach reduced the amount of vertebrate DNA amplified from the maggots' exteriors. No wash method affected the ability to recover DNA from the maggot crops. 相似文献
986.
The suicide rate on death row for the period 1976 through 1999 was found to be high (113 per 100,000 per year), some five times higher than the suicide rate for the male population of the United States. The death row suicide rate was predicted by features of the death row population (negatively with the population on death row) and by social indicators of the society as a whole (negatively with birth and divorce rates and positively with marriage rates). 相似文献
987.
Torres MC Osuna E Pérez-Cárceles MD Gómez-Zapata M Luna A 《The American journal of forensic medicine and pathology》2002,23(2):155-158
The authors evaluated the usefulness of the postmortem biochemical analysis of ionic ratios in different parts of the heart and their relation to cardiac damage caused by chest trauma, as observed by anatomopathologic study. Fifty-nine 59 cases were studied, selected from routine necropsies, and samples were taken from different sites of cardiac tissue. The cause of death was trauma in 40 cases and nontraumatic causes in 19 cases. The object of this study was to analyze the levels of Na+, K+, Ca+2, Mg+2, and Zn+2 in different zones of the heart, and the relationship between intracellular and extracellular ion ratios and the different causes of death and any anatomopathologic alterations observed. The biochemical tests revealed a possible relation between the ionic values and cause of death. Alterations in cell membrane permeability and corresponding modification of the ionic ratios were produced earlier than histologic alterations, which need longer to establish themselves whether or not they follow a traumatic process. 相似文献
988.
Sukhai A Harris C Moorad RG Dada MA 《The American journal of forensic medicine and pathology》2002,23(3):295-298
Self-immolation is an uncommon method of suicide, and its occurrence in South Africa is thus far unknown. This study aimed to determine the prevalence of self-immolation deaths and to establish a profile of these cases and the circumstances under which this condition occurs. A 5-year (1996-2000) retrospective review at a mortuary in Durban, South Africa, was conducted. Data were obtained from the Department of Forensic Medicine, the Medical Research Council's National Injury Mortality Surveillance System, and police and hospital records. During the study period, there were 12339 nonnatural deaths, of which 696 (5.6%) were suicides. Self-immolation accounted for 69 (0.6%) of all nonnatural deaths and 69 (9.9%) of all suicides. The subjects had a mean age of 31.2 years and were predominantly female (76.8%) and black (81.2%). The mean burn surface area was 63.3%, and the mean injury severity score was 36.9. Accelerant use was documented in 53 (76.8%) of cases, and paraffin was preferred. All cases occurred indoors. The proportion of suicides due to self-immolation in our study is excessive when compared with international studies that report figures between 0.9% and 2.2% of suicides. Additional studies are necessary to further elucidate the reasons for this discrepancy. 相似文献
989.
990.