全文获取类型
收费全文 | 221篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
224篇 |
出版年
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 8篇 |
2020年 | 1篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 3篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 3篇 |
2011年 | 5篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 7篇 |
2003年 | 10篇 |
2002年 | 14篇 |
2000年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有224条查询结果,搜索用时 21 毫秒
71.
Ivor Karavani? 《L'Anthropologie》2003,107(5):577-602
This paper presents the results obtained by lithic analysis of Early Upper Palaeolithic levels in Šandalja II Cave, Istria, Croatia. Technological and typological analysis of stone and typological analysis of bone artefacts have been carried out. Production of flakes in Aurignacian levels (G, F, E and E/F) is dominant, but blade and bladelets production is also present. Blades and bladelets were produced by direct soft hammer technique. Aurignacian people of Šandalja II produced their debitage mainly on local grey chert, which is often patinated. Šandalja II is one of the rare—if not the only—site with Aurignacian industry in eastern Adriatic region. The main reason for absence of such industry at other sites can be seen in scarce population or abandonment of some parts of this region. 相似文献
72.
Before the 90s, data on Paleolithic human occupation of southern Portugal was very scarce. During the last decade, the knowledge of the Upper Paleolithic of Algarve increased substantially due to the work of a research team based at the University of Algarve. The present paper is a report on the recent results from Algarve, focusing specially on the site of Vale Boi. It will present the chronology and stratigraphy of different human occupations from the early Upper Paleolithic up to the early Neolithic. It will focus on aspects of zooarchaeology and the exploitation of large and medium mammals as well as on marine fauna. In addition, we will present new data on stone and bone tools. Finally, we will also refer to the social and symbolic aspects present at the site, base on shell and teeth pendants and to an engraved plaquette with animal motifs. 相似文献
73.
艾叶是菊科(Compositae)植物艾(Artemisia argyi Lévl.et Vant.)的干燥叶,为常用中药材之一,药用历史悠久,具有苦燥辛散、理气血、温经脉、逐寒湿、止冷痛等功效,为重要的妇科用药,可用于治疗脘腹冷痛、经寒不调、宫冷不孕等证.此外,利用艾叶预防瘟疫已有悠久的历史.现代药理研究表明:艾叶是一种广谱抗菌抗病毒中药,对多种病毒和细菌有抑制和杀伤作用,对呼吸系统疾病以及心血管等慢性疾病有一定的防治作用[1-3].因此,将艾叶中的有效成分分别提取和纯化并加以分析以及功能检测,具有深远意义. 相似文献
74.
Parco cave, discovered in 1974, has yielded more than 50 objects fashioned of hard animal parts from levels dating to later phases of the Magdalenian. In the work described here, we have undertaken a technotypological analysis of this previously unstudied bone and antler assemblage. The osseous series from Parco are homogeneous and very similar to those from nearby sites of roughly the same time period; that is to say of the late Upper Magdalenian of the peninsular Mediterranean. The latter are composed primarily of hunting weapons dominated by antler projectile points, as well as eyed bone needles and a few shell ornaments. Technological analysis shows production in which there is a tight relationship between morphological type and raw material employed. The production schema saw the removal of blanks by means of groove and splinter technique, followed by shaping of pieces by scraping and finishing of them - in some cases by abrasion. 相似文献
75.
金龙胆草是传统道地中药材,但目前受到材料来源不足的限制,其应用和研究均受到很大限制,为更好地开发和应用该道地中药材,本研究以实验室野生金龙胆草和组培金龙胆草出发,分别采用热水浴和索式提取法对金龙胆草有效成份进行了提取和体外抑菌活性研究。结果表明,热水浴浸提法的抑菌效果优于索式提取法,均表现出对金黄色葡萄球菌和枯草芽孢杆菌这类革兰氏阳性菌有很好的抑制效果,最小抑菌浓度分别达到12.5 mg/mL和50 mg/mL。野生型提取液和组培型的提取液体外抑菌比较实验显示,野生型金龙胆草的抑菌效果要显著优于组培型金龙胆草提取液。这将为金龙胆草作为中药抗菌药的合理利用提供一定的指导作用,同时为减少抗生素的滥用造成的环境污染作出一定的贡献。 相似文献
76.
Within the Joannina serie, the molluscan fauna are found at two levels. An evolution has been observed within the Paludina group, but with lesser morphological development than those observed at Slavonia (Yougoslavia) and in the Island of Kos (Greece). Moreover, the gyrogonites, pollens and ostracodes demonstrate an increase in salinity during deposition and also give an Upper Pliocene age to this lacustrine serie. 相似文献
77.
The archaeological excavation of the cave of the Gardon has brought to light a dilated and nearly continuous stratigraphy for the Neolithic era. The analysis of lithic industry has showed the existence of variations between those neolithic layers, which are independents of the technological processes of tools productions. Four criteria allow us to characterize the occupation’s type of each layer. Compared to the excavations data and to sedimentological analysis, these results allow us to display the evolution of the intensity of occupations of the cave throughout the whole Neolithic. 相似文献
78.
79.
《Comptes Rendus Palevol》2016,15(5):581-594
Understanding the changes in the technological organization of prehistoric hunter–gatherers is important to research into hominin foraging activities. During the Middle Paleolithic, the coexistence or the replacement between Levallois and discoid technologies has frequently been recorded, but there is still no clear understanding of the reasons for their alternating and fragmented use in the archaeological record. This paper aims to contribute with new data to the current debate, by exploring the chert assemblages from levels O and M of the Abric Romaní rock-shelter. The results reveal that the change from Levallois in level O to discoid in level M is accompanied by the use of different axes of mobility, a reduction in the foraging radius and a more careful management of raw materials. A cross comparison with other archaeological evidences indicates the general pattern in the Northeast of the Iberian Peninsula during the late Middle Paleolithic, in which the use of Levallois technology is associated with chert and high mobility patterns whereas discoid technology is more closely linked to the use of local raw materials and a lower degree of mobility. The modifications to the mountainous environments and to the distribution of preferred prey animals may have influenced the Neanderthals’ mobility patterns and contributed to modifying their technical behaviours in order to obtain better foraging incomes. 相似文献
80.
Naoko Ishibe Andrew N. Freedman Arthur M. Michalek Christine Iacobuziodonahue Curtis J. Mettlin Nicholas J. Petrelli John E. Asirwatham Stanley R. Hamilton 《Biomarkers》2000,5(3):225-234
Although a positive association between cigarette smoking and colorectal adenoma development is consistently found, the association with colorectal cancer remains controversial. We evaluated the potential roles of p27Kip1 and bcl-2 protein expressions in conjunction with cigarette smoking exposure and colorectal cancer risk in a hospital-based case-control study. A total of 163 colorectal cancer patients from Roswell Park Cancer Institute and Buffalo General Hospital and 326 healthy controls responded to a standardized questionnaire on colorectal cancer risk factors including detailed information on their history of cigarette smoking; 110 of the patientsfitumours were available for immunohistochemical analysis of p27Kip1 and bcl-2 protein overexpression. An avidin?biotin immunoperoxidase procedure was used to determine expression after incubation with mouse monoclonal p27Kip1 and mouse monoclonal bcl-2 antibodies, respectively. A statistically significant trend for total pack-years of smoking was found when p27Kip1 positive cases were compared with p27Kip1 negative cases (trend test, p = 0.007). Although a weak inverse association was observed with smoking exposure among p27Kip1 negative tumour cases in comparison to controls, a significant dose?response association was seen with p27Kip1 positive tumours. The relative risk of developing a p27Kip1 positive tumour was estimated to be 1.17 (95% CI 0.54?2.54) for those with less than 20 pack-years, 1.95 (95 % CI 0.95?3.97) for those with 20?39 pack-years, and 2.25 (95% CI 1.14?4.45) for those with greater than 39 pack-years of smoking exposure (trend test, p = 0.009) when compared with controls. When cases with bcl-2 expression were compared with cases without bcl-2 expression, suggestion of a trend was also observed with pack-years smoked (trend test, p = 0.09). In our study of 110 patients with sporadic colorectal cancer and 326 controls, we observed differences in associations between cigarette smoking and expressions in p27Kip1 and bcl-2. Our data suggest that bcl-2 overexpression (or a bcl-2 dependent pathway) is associated with cigarette smoking in the development of colorectal cancer, whereas a loss of p27Kip1 expression is not. These associations indicate that there is aetiological heterogeneity in colorectal cancer development, and that they can indirectly allude to where these changes in protein expression occur in the adenoma?carcinoma sequence (i.e. early versus late events). 相似文献