全文获取类型
收费全文 | 17142篇 |
免费 | 421篇 |
专业分类
各国政治 | 815篇 |
工人农民 | 667篇 |
世界政治 | 1125篇 |
外交国际关系 | 550篇 |
法律 | 10617篇 |
中国政治 | 103篇 |
政治理论 | 3549篇 |
综合类 | 137篇 |
出版年
2020年 | 173篇 |
2019年 | 235篇 |
2018年 | 300篇 |
2017年 | 351篇 |
2016年 | 360篇 |
2015年 | 260篇 |
2014年 | 313篇 |
2013年 | 1680篇 |
2012年 | 356篇 |
2011年 | 404篇 |
2010年 | 350篇 |
2009年 | 397篇 |
2008年 | 421篇 |
2007年 | 445篇 |
2006年 | 436篇 |
2005年 | 387篇 |
2004年 | 366篇 |
2003年 | 395篇 |
2002年 | 362篇 |
2001年 | 659篇 |
2000年 | 570篇 |
1999年 | 485篇 |
1998年 | 250篇 |
1997年 | 198篇 |
1996年 | 200篇 |
1995年 | 193篇 |
1994年 | 204篇 |
1993年 | 198篇 |
1992年 | 339篇 |
1991年 | 386篇 |
1990年 | 370篇 |
1989年 | 373篇 |
1988年 | 364篇 |
1987年 | 368篇 |
1986年 | 403篇 |
1985年 | 389篇 |
1984年 | 347篇 |
1983年 | 322篇 |
1982年 | 220篇 |
1981年 | 211篇 |
1980年 | 176篇 |
1979年 | 264篇 |
1978年 | 170篇 |
1977年 | 175篇 |
1976年 | 146篇 |
1975年 | 145篇 |
1974年 | 170篇 |
1973年 | 159篇 |
1972年 | 128篇 |
1971年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
996.
Research has shown that the prevalence of deliberate self-harm (DSH) is higher in adolescents than in adults, but little is known about other differences. In this study we compare adolescent and adult DSH-patients regarding factors contributing to the suicidal act. In two regions in Norway, 98 persons under 20 years of age and 83 older persons were interviewed following an act of DSH. They were compared regarding intentions involved in the DSH, precipitating circumstances, level of suicidal intent, medical seriousness of the act, depression, hopelessness, and self-esteem. Few differences were found. The adults more often wanted to escape from unbearable thoughts or situations, or to receive care and attention. Adults also reported a slightly higher level of medical seriousness of the DSH act, more psychiatric problems, and substance abuse. The similarities between young and adult DSH-patients are striking. The differences found are most likely related to factors of age itself, such as cognitive immaturity, impulsivity, and lack of experience in enduring problems. 相似文献
997.
998.
The use of a new technique, Fourier transform infrared (FTIR) chemical imaging, has been demonstrated for the enhancement of latent fingermarks on a number of surfaces. Images of untreated fingermarks on glass backgrounds with excellent ridge detail were acquired using infrared chemical imaging. High quality fingermarks on glass backgrounds were also developed using ethyl cyanoacrylate (super glue) fuming and subsequent infrared chemical imaging. This new method allows the collection of images from backgrounds that traditionally pose problems for current fingermark detection methods. The background may, for example, be highly colored, have a complex pattern, or possess other pattern or image characteristics that make it difficult to separate fingermark ridges using traditional optical or luminescent visualization. One background that has proven to be a challenging surface for the development of latent fingermarks is the Australian polymer banknote. To demonstrate the power and applicability of infrared chemical imaging, fingermarks fumed with ethyl cyanoacrylate were successfully imaged from Australian polymer banknotes. 相似文献
999.
In a second test of an arthropod saturation hypothesis, we analyzed if the on-campus Anthropology Research Facility (ARF) at the University of Tennessee, Knoxville, with its 20+ yr history of carcass enrichment, is comparable to non-enriched sites in community structure of predatory and parasitic arthropods that prey upon the sarcosaprophagous fauna. Over a 12-day period in June 1998, using pitfall traps and sweep nets, 10,065 predaceous, parasitic, and hematophagous (blood-feeding) arthropods were collected from freshly euthanized pigs (Sus scrofa L.) placed at ARF and at three surrounding sites various distances away (S2-S4). The community structure of these organisms was comparable in most paired-site tests with respect to species composition, colonization rates, and evenness of pitfall-trap abundances on a per carcass basis. Site differences were found in rarefaction tests of both sweep-net and pitfall-trap taxa and in tests of taxonomic evenness and ranked abundances of sweep-net samples. Despite these differences, no evidence was found that the predatory/parasitic fauna at ARF was impoverished with fewer but larger populations as a result of carcass enrichment. Comparison of the sarcosaprophagous and predatory/parasitic faunas revealed a tighter (and more predictable) linkage between carrion feeders (sarcosaprovores) and their carrion than between carrion feeders and their natural enemies (predators and parasitoids), leading us to conclude that ARF is more representative of surrounding sites with respect to the sarcosaprovore component than to the predatory/parasitic component within the larger carrion-arthropod community. 相似文献
1000.
A few papers in the literature reported incident deaths by acute ketamine poisoning. In this paper, we report an unusual homicide caused by chronic ketamine poisoning. The victim was a 34-year old married woman with no previous medical history (except as reported herein) who died in her own home. The court investigation revealed that she was chronically poisoned by her husband over a period of about one year in an act of homicide. Determination of ketamine concentrations in autopsy specimens was carried out with gas-chromatography/mass spectrometry (GC-MS). The results showed that ketamine concentration was 21 microg/mL in gastric contents, 3.8 microg/mL in blood and 1.2 microg/mL in urine. The most striking forensic findings were cardiac muscle fibrosis and hyaline degeneration of small arteries in victim's heart, the pathological features of ketamine poisoning previous reported only in animal studies. 相似文献