全文获取类型
收费全文 | 7184篇 |
免费 | 209篇 |
专业分类
各国政治 | 346篇 |
工人农民 | 241篇 |
世界政治 | 487篇 |
外交国际关系 | 191篇 |
法律 | 4769篇 |
中国共产党 | 1篇 |
中国政治 | 49篇 |
政治理论 | 1261篇 |
综合类 | 48篇 |
出版年
2020年 | 86篇 |
2019年 | 89篇 |
2018年 | 106篇 |
2017年 | 137篇 |
2016年 | 142篇 |
2015年 | 117篇 |
2014年 | 123篇 |
2013年 | 664篇 |
2012年 | 186篇 |
2011年 | 184篇 |
2010年 | 139篇 |
2009年 | 135篇 |
2008年 | 188篇 |
2007年 | 194篇 |
2006年 | 195篇 |
2005年 | 194篇 |
2004年 | 195篇 |
2003年 | 185篇 |
2002年 | 178篇 |
2001年 | 328篇 |
2000年 | 286篇 |
1999年 | 198篇 |
1998年 | 93篇 |
1997年 | 69篇 |
1996年 | 61篇 |
1995年 | 74篇 |
1994年 | 72篇 |
1993年 | 68篇 |
1992年 | 152篇 |
1991年 | 153篇 |
1990年 | 162篇 |
1989年 | 167篇 |
1988年 | 162篇 |
1987年 | 153篇 |
1986年 | 174篇 |
1985年 | 167篇 |
1984年 | 109篇 |
1983年 | 116篇 |
1982年 | 67篇 |
1981年 | 75篇 |
1980年 | 59篇 |
1979年 | 73篇 |
1978年 | 76篇 |
1977年 | 57篇 |
1975年 | 72篇 |
1974年 | 90篇 |
1973年 | 80篇 |
1972年 | 71篇 |
1970年 | 52篇 |
1969年 | 60篇 |
排序方式: 共有7393条查询结果,搜索用时 31 毫秒
951.
952.
953.
954.
955.
956.
This articles is written in a personal capacity and should not be attributed in any way to the ICAO Secretariat or the United Nations. 相似文献
957.
E I Rogaev E Iu Syrokvasheva M G Pimenov T V Stegnova 《Sudebno-meditsinskaia ekspertiza》1992,35(1):10-14
Blood stains on a knife were identified by DNA genotyposcopy. The statistical validation method has confirmed that the blood stains on material evidence belonged to the victim, the probability of random coincidence being less than 10(-11). The efficacy of using hypervariable locus-specific DNA probes and the possibility of detecting DNA impressions in blood stains stored for more than 3 months have been demonstrated. 相似文献
958.
Study of dental root surfaces prompted the authors to add to the routine odontogram 28 more maxillary surfaces and 22 mandibular surfaces, this making a total of 210 diagnostic signs. Employment of amplified panoramic roentgenography permitted the authors to detect specific features of the dental cavity, root canals, periodontal fissure structure, the presence of caries and its complications, inflammatory and systemic involvement, injury to the jaws and teeth. Visual examination of dental status and application of panoramic roentgenography will help improve forensic medical personal identification. 相似文献
959.
P Betz A Nerlich J Wilske I Wiest C Kunze O Peschel R Penning 《Forensic science international》1992,53(2):193-202
We monitored the immunohistochemically determined amount of surfactant-producing alveolar type II cells in human fetal lung using polyclonal antibodies against apoprotein B and C of human pulmonary surfactant. Lungs of 30 dead-born fetuses without lung affection aged between 15 and 38 weeks of gestation were evaluated and the surface density of surfactant-producing alveolar type II cells was determined by morphometry. In lungs of fetuses with a gestational age less than 22 weeks no relevant number of positively reacting cells could be found. Between the 22nd and 29th week a progressive increase with considerable inter-individual variability was observed. From the 30th week on the number of the type II pneumocytes appeared rather constant without further significant increase. We provide evidence that the immunohistochemical detection of surfactant-producing alveolar type II cells is useful for the determination of the age of unknown and especially fragmented fetuses: The lack of surfactant-producing alveolar type II cells in fetal lungs before the 22nd week allows a rather safe distinction between fetal lungs of higher age from those of lesser age. Between the 22nd and 29th week an age-dependent increase in the number of these cells occurs with wide inter-individual variability allowing only an approximate age determination. In particular, this may be an important piece of information in fragmented fetal corpses. Furthermore, the number of surfactant-producing alveolar type II cells provides additional information on pulmonary maturation and may thus be helpful in the estimation of a theoretical survival chance. 相似文献
960.