全文获取类型
收费全文 | 1888篇 |
免费 | 86篇 |
国内免费 | 349篇 |
出版年
2024年 | 9篇 |
2023年 | 54篇 |
2022年 | 71篇 |
2021年 | 103篇 |
2020年 | 70篇 |
2019年 | 84篇 |
2018年 | 75篇 |
2017年 | 75篇 |
2016年 | 88篇 |
2015年 | 88篇 |
2014年 | 130篇 |
2013年 | 136篇 |
2012年 | 148篇 |
2011年 | 141篇 |
2010年 | 104篇 |
2009年 | 126篇 |
2008年 | 115篇 |
2007年 | 119篇 |
2006年 | 96篇 |
2005年 | 85篇 |
2004年 | 61篇 |
2003年 | 66篇 |
2002年 | 58篇 |
2001年 | 42篇 |
2000年 | 37篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 18篇 |
1994年 | 14篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有2323条查询结果,搜索用时 15 毫秒
171.
172.
Congruent phylogenetic and fossil signatures of mammalian diversification dynamics driven by Tertiary abiotic change 下载免费PDF全文
Juan L. Cantalapiedra Manuel Hernández Fernández Beatriz Azanza Jorge Morales 《Evolution; international journal of organic evolution》2015,69(11):2941-2953
Computational methods for estimating diversification rates from extant species phylogenetic trees have become abundant in evolutionary research. However, little evidence exists about how their outcome compares to a complementary and direct source of information: the fossil record. Furthermore, there is virtually no direct test for the congruence of evolutionary rates based on these two sources. This task is only achievable in clades with both a well‐known fossil record and a complete phylogenetic tree. Here, we compare the evolutionary rates of ruminant mammals as estimated from their vast paleontological record—over 1200 species spanning 50 myr—and their living‐species phylogeny. Significantly, our results revealed that the ruminant's fossil record and phylogeny reflect congruent evolutionary processes. The concordance is especially strong for the last 25 myr, when living groups became a dominant part of ruminant diversity. We found empirical support for previous hypotheses based on simulations and neontological data: The pattern captured by the tree depends on how clade specific the processes are and which clades are involved. Also, we report fossil evidence for a postradiation speciation slowdown coupled with constant, moderate extinction in the Miocene. The recent deceleration in phylogenetic rates is connected to rapid extinction triggered by recent climatic fluctuations. 相似文献
173.
The genus Stigmatijanus Wei, 2007 is recorded from Korea for the first time. A diagnosis of the genus is briefly discussed. A new species, Stigmatijanus koreanus sp. nov., is described from Mt. Homyeong, Gyeonggi-do, South Korea. A key to the three species of the genus is provided. 相似文献
174.
中国老鹳草属(牻牛儿苗科)归化植物新记录 总被引:1,自引:1,他引:0
叶康 《热带亚热带植物学报》2015,23(1):34-36
报道在江苏省发现的中国归化植物新记录刻叶老鹳草(Geranium dissectumL.),对其形态特征进行了描述,并提供了形态照片。 相似文献
175.
Two new species of oribatid mites of the genus Scapheremaeus (Oribatida, Cymbaeremaeidae), Scapheremaeus
gibbus
sp. n. and Scapheremaeus
luxtoni
sp. n., are described from New Zealand. Scapheremaeus
gibbus
sp. n. is morphologically most similar to Scapheremaeus
humeratus Balogh & Mahunka, 1967, but differs from the latter by the number of notogastral, genital and adanal setae, morphology of bothridial setae, position of adanal lyrifissures and absence of humeral processes. Scapheremaeus
luxtoni
sp. n. is morphologically most similar to Scapheremaeus
yamashitai Aoki, 1970, but differs from the latter by the morphology of notogastral and rostral setae, morphology of leg solenidia φ2 and development of humeral processes. The species Scapheremaeus
zephyrus Colloff, 2010 is recorded for the first time in New Zealand. An identification key to the known New Zealand species of Scapheremaeus is provided. 相似文献
176.
Four species of the ant genus Ponera Latreille, 1804, are recorded from India. The present study reports one new species Ponera
sikkimensis
sp. n., a divergent population of Ponera
indica Bharti & Wachkoo, 2012 and one new record, Ponera
paedericera Zhou, 2001 from India. An identification key and distributions for the four known Indian species of Ponera based on the worker caste are provided. 相似文献
177.
Sergey G. Ermilov Dorothee Sandmann Bernhard Klarner Rahaju Widyastuti Stefan Scheu 《ZooKeys》2015,(539):11-51
Seven new species of oribatid mites of the genus Galumna are described from litter and soil materials of Sumatra, Indonesia. A new subgenus, Galumna (Atypicogalumna)
subgen. n., is proposed; it differs from all galumnid genera and subgenera by the simultaneous presence of porose areas and sacculi on the notogaster (vs. either porose areas or sacculi present). Galumna (Galumna) calva Starý, 1997 is recorded for the first time in the Oriental region, and Galumna (Galumna) sabahna Mahunka, 1995 is recorded for the first time in the Indonesian fauna. 相似文献
178.
The Chinese species of the genera Omicrogiton Orchymont, 1919, Peratogonus Sharp, 1884 and Mircogioton Orchymont, 1937 are reviewed, diagnosed and keyed. Mircogioton and Omicrogiton are reported for the first time from China, Peratogonus for the first time for mainland China. Five species are recognized: Omicrogiton
coomani Balfour-Browne, 1939 (Guangdong, Hongkong), Omicrogiton
hainanensis
sp. n. (Hainan), Omicrogiton
roberti
sp. n. (Hainan), Mircogioton
coomani Orchymont, 1937 (Yunnan), and Peratogonus
reversus Sharp, 1884 (Guangdong, Jiangxi, Taiwan). Lectotype of Omicrogiton
coomani is designated. Mircogioton
cognitus (Malcolm, 1981), syn. n. is considered a junior subjective synonym of Mircogioton
coomani Orchymont, 1939. Species of Mircogioton and Omicrogiton inhabit decaying banana trunks, whereas Peratogonus
reversus was always collected from moist forest leaf litter. 相似文献
179.
180.