全文获取类型
收费全文 | 749篇 |
免费 | 71篇 |
国内免费 | 88篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 30篇 |
2020年 | 28篇 |
2019年 | 31篇 |
2018年 | 27篇 |
2017年 | 28篇 |
2016年 | 28篇 |
2015年 | 25篇 |
2014年 | 32篇 |
2013年 | 53篇 |
2012年 | 26篇 |
2011年 | 37篇 |
2010年 | 34篇 |
2009年 | 51篇 |
2008年 | 45篇 |
2007年 | 40篇 |
2006年 | 60篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 28篇 |
2000年 | 19篇 |
1999年 | 14篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 15篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 9篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有908条查询结果,搜索用时 15 毫秒
901.
Description of a new species of Hoolock gibbon (Primates: Hylobatidae) based on integrative taxonomy
下载免费PDF全文
![点击此处可从《American journal of primatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
902.
To compare the nutrient economy of woody plants at timberline of Mt. Fuji, seasonal changes in nitrogen content in leaves
were examined. There was remarkable difference in seasonal changes in leaf nitrogen content betweenAlnus maximowiczii and other deciduous trees at same habitat.A. maximowiczii scarcely withdrew the leaf nitrogen to woody part during the shedding period, while the other species withdrew about half
of the leaf nitrogen to woody part. 相似文献
903.
Suresh Jivan Gadher Łukasz Marczak Magdalena Łuczak Maciej Stobiecki Piotr Widlak 《Expert review of proteomics》2016,13(1):5-7
Every year since 2007, the Central and Eastern European Proteomic Conference (CEEPC) has excelled in representing state-of-the-art proteomics in and around Central and Eastern Europe, and linking it to international institutions worldwide. Its mission remains to contribute to all approaches of proteomics including traditional and often-revisited methodologies as well as the latest technological achievements in clinical, quantitative and structural proteomics with a view to systems biology of a variety of processes. The 9th CEEPC was held from June 15th to 18th, 2015, at the Institute of Bioorganic Chemistry, Polish Academy of Sciences in Poznań, Poland. The scientific program stimulated exchange of proteomic knowledge whilst the spectacular venue of the conference allowed participants to enjoy the cobblestoned historical city of Poznań. 相似文献
904.
Konstantina Agiadi Efterpi Koskeridou Maria Triantaphyllou Angela Girone Vasileios Karakitsios 《Geobios》2013
The Pliocene Eastern Mediterranean fish record is revealed through the study of a 60-m thick stratigraphic sequence near the village Voutes (Heraklion, Crete). Forty-two species belonging to twenty families are identified. Calcareous nannoplankton biostratigraphy places the studied sequence within the biozone MNN16a (latest Zanclean). The stratigraphic distribution of 31 species is modified. Among these, 12 species are reported for the first time in the Eastern Mediterranean Zanclean, while 19 species are first reported outside the Ionian Sea. The Voutes fish fauna presents a diversified benthic and benthopelagic assemblage filling a significant gap in the fossil record. 相似文献
905.
《Geobios》2020
The abundance of the major coralline algal groups has been investigated and quantified in the coralline-rich facies of the Miocene shallow-water carbonates of the Eratosthenes Seamount (eastern Mediterranean, off-shore Cyprus). The analysis is based on the quantification of the most easily-recognizable groups of coralline algae in order to provide a user-friendly approach for palaeobathymetric reconstructions. Coralline algal distribution through the core suggests water depth estimates generally similar to those based on the composition of the skeletal assemblage and the benthic foraminiferal association in particular. The only noticeable difference occurs in the rhodolith and coral facies, where algal distribution suggests deeper waters than those indicated by benthic foraminifera. The distribution pattern of the major groups suggests that the ratio between Hapalidiales and Corallinales is the most reliable indicator of water-depth. The comparison with other models available in literature highlights a general zonation useful for the study of tropical, middle to late Miocene oligotrophic carbonates. Very shallow settings (0–20 m) are overwhelmingly dominated by Corallinales; in slightly deeper settings (20–40 m) Hapalidiales are more abundant, especially if the sea-floor is shaded (for example by a macrophyte canopy). Between 40 and 60 m, Hapalidiales dominate but Corallinales are still common, while below 60 m Corallinales are very rare. In non-oligotrophic environments this zonation is not reliable and, due to the reduced water clarity related to the high primary productivity, Hapalidiales clearly dominate even in very shallow settings. 相似文献
906.
《Comptes Rendus Palevol》2014,13(8):737-746
The spatial relationships of the Early Oldowan toolmakers with their environment have been so far addressed through raw material procurement analyses and the characterization of hominid habitat. This paper proposes to integrate these two approaches into a broader spatial analysis encompassing archaeological and environmental data (palaeontological, geological and isotopic data) from Member F and lower Member G of the Shungura Formation (Lower Omo Valley, Ethiopia). Heterogeneity in data resolution induces a multiscale approach with three levels of analysis. The level of occurrence complex allows focusing on the characterization of archaeological occurrences and on their environmental settings. The level of “study area” allows working on hominid habitats and on their raw material procurement behaviours. Finally, at the Shungura Formation scale, we can address temporal issues related to the evolution of spatial behaviours between Member F and the lower part of Member G, ca. 2.3 to 2 million years (Ma). 相似文献
907.
Mitsuhiro Takayama 《Ichthyological Research》2002,49(2):165-170
The spawning period of the Far Eastern brook lamprey, Lethenteron reissneri, in the headstream of the Himekawa River is estimated to be between mid-March and late May with the peak of spawning activity
between early April and early May. The sex ratio (female:male) in 1999 ranged from 1 : 2.5 to 1 : 3.0 (mean 1 : 2.8) and in
2000 from 1 : 0.8 to 1 : 4.0 (mean 1 : 2.4). In >90% of the observations of spawning nests, males outnumbered females. The
construction area of spawning nests tended to shift upstream during the spawning period. The nests were constructed at water
depths between 5 and 70 cm, water velocity between 10 and 30 cm/s, and on substrate with pebbles of 5–20 mm in diameter. Lethenteron reissneri constructed nests on substrate similar with Petromyzon marinus, but at shallower points and in areas with a slower water velocity.
Received: April 2, 2001 / Revised: December 12, 2001 / Accepted: December 27, 2001 相似文献
908.
文章从三叶虫的头尾搭配问题的讨论对"也论Protaitzehoia Yang三叶虫的分类位置"一文中置于原太子河虫属的某些尾部的可靠性提出了质疑,认为插图2中的尾(K),由于缺少宽而下凹的尾边缘,应属于Stephanocare Monke,1903一属的尾部;插图2中的尾(L)的归属尚难定论.将原太子河虫属的头盖、活动颊、尾部、唇瓣与Cheilocephalus Berkey,1898属的头盖、活动颊、尾部、唇瓣对比后,认为原太子河虫属应归属Cheilocephalidae Shaw,1956. 相似文献