全文获取类型
收费全文 | 1190篇 |
免费 | 12篇 |
国内免费 | 18篇 |
专业分类
系统科学 | 32篇 |
丛书文集 | 20篇 |
教育与普及 | 4篇 |
理论与方法论 | 10篇 |
现状及发展 | 14篇 |
综合类 | 1017篇 |
自然研究 | 123篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 9篇 |
2015年 | 25篇 |
2014年 | 53篇 |
2013年 | 54篇 |
2012年 | 179篇 |
2011年 | 92篇 |
2010年 | 84篇 |
2009年 | 74篇 |
2008年 | 67篇 |
2007年 | 63篇 |
2006年 | 55篇 |
2005年 | 37篇 |
2004年 | 44篇 |
2003年 | 34篇 |
2002年 | 26篇 |
2001年 | 38篇 |
2000年 | 21篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 24篇 |
1991年 | 15篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 2篇 |
排序方式: 共有1220条查询结果,搜索用时 15 毫秒
991.
从杀虫植物苦皮藤中分离得到两个新骨架生物碱 ,被命名为 1 ,3—氧氮杂环已烷化合物A、B。它们的生物活性被美国国际卫生和抗癌研究中心 (NCI)筛选。通过体外定向肿瘤筛选 ,9个不同种类的 60个细胞株毒理实验结果表明 ,化合物生物碱B显示温和的细胞抗癌活性 ,抗非小细胞肺癌 (NCI—H2 3) ,抑癌细胞生长率GI50 =3.0× 1 0 - 5m(9.6μg/mL)。生物碱A的细胞毒理正在筛选中 相似文献
992.
A survey to explore the earthworm fauna of New Caledonia was carried out between 14 January 2014 and 2 April 2014. Altogether, 24 earthworm species were recorded, of which eight belong to the native genus Acanthodrilus including four species new to science, Acanthodrilus barrieri, A. doanus, A. millei and A. ouenghianus spp. nov., raising the number of Acanthodrilus species in New Caledonia to 29. The 16 recorded peregrine species are distributed among five families, namely Benhamiidae (5 spp.), Eudrilidae (1 sp.), Megascolecidae (8 spp.), Moniligastridae (1 sp.) and Rhinodrilidae (1 sp.).
www.zoobank.org/urn:lsid:zoobank.org:pub:4E0A6295-A2FA-43BB-993D-BB00AFF54406 相似文献
993.
994.
《Journal of Natural History》2012,46(2):165-195
The Geometrine genus Metallolophia is revised. In addition to the 11 species known, five new species are described as new. All the known species are redescribed and lectotypes are designated for M. opalina (Warren), M. arenaria (Leech) and M. danielaria (Oberthür) (=M. arenaria (Leech)). The male of M. ocellata (Warren) and the females of M. medullosa Inoue and M. devecisi Herbulot are described for the first time. The generic characters based on all species are summarized and a key to all taxa is given. Illustrations of moths and genitalia are presented. The new and revised taxa are: Metallolophia purpurivenata sp. nov., Metallolophia cuneataria sp. nov., Metallolophia inanularia sp. nov., Metallolophia flavomaculata sp. nov., Metallolophia stueningi sp. nov. and Metallolophia ostrumaria Xue, syn. nov. (of Metallolophia albescens Inoue). 相似文献
995.
996.
《Journal of Natural History》2012,46(21-24):1343-1366
The scale insect families Asterolecaniidae and Eriococcidae are discussed from New Caledonia. One new genus Oacoccus gen. nov., and a new species Oacoccus nothofagi sp. nov. on Nothofagus sp., are described in the Asterolecaniidae, and a new species Eriococcus millei sp. nov. is described in the Eriococcidae. A new genus Rhopalotococcus gen. nov., and two new species Rhopalotococcus dugdalei sp. nov. and Rhopalotococcus metrosideri sp. nov., are also described in the Eriococcidae. Both species induce leaf galls on Metrosideros sp. Keys are provided for all the New Caledonian genera and species in the families Asterolecaniidae and Eriococcidae. 相似文献
997.
Renée Jennifer Raphael 《Studies in history and philosophy of science》2011,42(4):479-491
This study proposes an explanation for the choice of topics Galileo addressed in Day 1 of his 1638 Two New Sciences, a section of the work which has long puzzled historians of science. I argue that Galileo’s agenda in Day 1, that is the topics he discusses and the questions he poses, was shaped by contemporary teaching commentaries on Books 3 through 8 of Aristotle’s Physics. Building on the insights and approach of theorists of reader reception, I confirm this interpretation by examining the response of professors of natural philosophy at the Jesuit Collegio Romano to Galileo’s text. 相似文献
998.
《Journal of Natural History》2012,46(3):333-340
We describe nematomorph specimens from New Zealand and compare them to museum specimens of Gordius paranensis Camerano, 1892 from Chile. Although specimens from New Zealand and Chile vary from each other, especially in body dimensions and coloration, literature data on other South American specimens of G. paranensis correspond to the New Zealand specimens which are therefore considered to belong to this species. A conspicuous character of G. paranensis is a precloacal, parabolic row of bristles that has been observed elsewhere only in G. difficilis (Montgomery, 1898). 相似文献
999.
根据新巴塞尔资本协议的基本原则及巴塞尔银行监管委员会推荐的确定资本金的VaR方法,结合中国商业银行目前信用风险管理的实际情况,比较分析CreditMet-ricsTM模型和CPV模型的基本原理和参数选择的共性及差异,对两模型各自特点做出客观评价,结果发现运用CPV模型有利于提高信用风险度量的精确性,为商业银行信用风险管理提供了有益的借鉴. 相似文献
1000.
李矿明 《南京林业大学学报(自然科学版)》1989,32(4):85
作者在福建省九龙江流域中部作木本植物区系研究时,获得了一些第一手资料,整理如下。文中所引证的标本,凡未注明采集人者,均为作者本人采集,标本藏于南京林业大学树木标本室。新分布的采集地点均为福建省华安县境内的区、乡地名。 相似文献