全文获取类型
收费全文 | 14445篇 |
免费 | 244篇 |
国内免费 | 292篇 |
专业分类
系统科学 | 166篇 |
丛书文集 | 375篇 |
教育与普及 | 194篇 |
理论与方法论 | 157篇 |
现状及发展 | 100篇 |
综合类 | 13484篇 |
自然研究 | 505篇 |
出版年
2024年 | 24篇 |
2023年 | 41篇 |
2022年 | 88篇 |
2021年 | 90篇 |
2020年 | 119篇 |
2019年 | 101篇 |
2018年 | 103篇 |
2017年 | 129篇 |
2016年 | 142篇 |
2015年 | 272篇 |
2014年 | 703篇 |
2013年 | 508篇 |
2012年 | 1271篇 |
2011年 | 1040篇 |
2010年 | 823篇 |
2009年 | 852篇 |
2008年 | 989篇 |
2007年 | 1291篇 |
2006年 | 1050篇 |
2005年 | 913篇 |
2004年 | 739篇 |
2003年 | 679篇 |
2002年 | 586篇 |
2001年 | 484篇 |
2000年 | 355篇 |
1999年 | 246篇 |
1998年 | 161篇 |
1997年 | 194篇 |
1996年 | 146篇 |
1995年 | 146篇 |
1994年 | 128篇 |
1993年 | 122篇 |
1992年 | 80篇 |
1991年 | 88篇 |
1990年 | 67篇 |
1989年 | 84篇 |
1988年 | 51篇 |
1987年 | 23篇 |
1986年 | 34篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1981年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Marcelo Passamani 《Journal of Natural History》2015,49(19-20):1225-1234
The use of space by animals is determined by environmental conditions, biological and ecological adaptations and interactions and mostly by resource availability. We sampled two species of Neotropical mammals to investigate their use of different strata in Atlantic Forest habitat in Brazil, as well as the home range sizes and movements of both sexes of each species. We found no difference in home ranges and movements between the sexes and species, but we found differences in the use of strata, with Gracilinanus microtarsus mostly using the canopy and Marmosops incanus using the ground. Gracilinanus microtarsus males mostly use the understorey in the wet season and the canopy in the dry season. We believe that these patterns of strata use reflect intrinsic characteristics of the species; and the shifts in resources and interspecific competition, which are lower in the dry season, seem to be responsible for the shifts in space use observed for G. microtarsus males. We recommend studies with spool-and-line techniques or radio tracking to further test refined hypotheses regarding the use of space, including the role of territoriality in females. 相似文献
102.
Tingting Yu 《Journal of Natural History》2015,49(9-10):509-526
Pseudelzalia longiseta gen. nov, sp. nov. and Paramonohystera sinica sp. nov. from subtidal sediment in the East China Sea are described. Pseudelzalia is characterized by 6 labial papillae and 10 cephalic setae, cylindrical buccal cavity, elongate (>2 anal body diameter) spicules, and conico-cylindrical tail devoid of terminal setae. It differs from Elzalia by the absence of terminal setae. Pseudelzalia longiseta sp. nov. is 647–853 μm long, has 7–8 μm long cervical setae, 11–14 μm long caudal setae, 25–41 μm long spicules about 2.1–2.7 anal diameter, and pointed tail-tip. Paramonohystera sinica possesses 12 cephalic setae, a character found in four congeners: Paramonohystera buetschlii (Bresslau and Schuurmans Stekhoven in Schuurmans Stekhoven, 1935, Paramonohystera pilosa Boucher, 1971, Paramonohystera concinna Lorenzen, 1977 and Paramonohystera halerba Fadeeva and Belogurov, 1987. It differs from P. buetschlii by shorter body (933–1023 μm versus 2000–2200 μm); from P. pilosa by the much shorter spicules (79–88 μm versus 167 μm) and narrower head (13–16 µm versus 32 µm); from P.concinna by smooth cephalic setae (versus segmented); and from P. halerba by the absence of two rows of setae on the ventral side of the tail (versus present). Based on the evaluation of nominal species, we recognize 14 valid species and provide an emended diagnosis and a tabular key for Paramonohystera.http://www.zoobank.org/urn:lsid:zoobank.org:pub:474B8F17-AED7-4078-8176-DFC499B78526 相似文献
103.
《Journal of Natural History》2012,46(33):3039-3058
During a soil zoology expedition to Sao Tomé Island, among other members of the soil fauna, earthworms were collected. During this collecting trip some 170 earthworm specimens belonging to 18 species were gathered of which two, Dichogaster (Diplothecodrilus) coeruleoviridis and Dichogaster (Diplothecodrilus) zicsii, proved to be new to science. In addition, a small sample from the same locality was also examined and Dichogaster (Dichogaster) thomeana Cognetti, 1910 was removed from synonymy of Dichogaster (Dichogaster) greeffi Michaelsen, 1902. 相似文献
104.
《Journal of Natural History》2012,46(30):2759-2794
New data on the warm temperate and tropical east Atlantic Bathyporeia species are presented. Four new species are described: Bathyporeia cunctator sp. nov. from South Africa, B. chevreuxi sp. nov. from Senegal, B. gladiura sp. nov. from South Africa, and B. griffithsi sp. nov. from Namibia. Bathyporeia cunctator sp. nov. and B. chevreuxi sp. nov. are very closely related to the west European B. tenuipes Meinert, 1877 and the Mediterranean B. lindstromi Stebbing, 1906; these four cryptic species forming the complex tenuipes. Bathyporeia griffithsi sp. nov. and B. gladiura sp. nov. are highly distinctive new species. The morphotype “sunnivae” of Bathyporeia guilliamsoniana is recorded for the first time outside the Mediterranean Sea, in the Canary Islands. An identification key to all known Bathyporeia species is given. 相似文献
105.
106.
《Journal of Natural History》2012,46(29-32):1989-2005
From 1997 to 1999, the fauna of free‐living Platyhelminthes of the rias ecosystem was studied along the Galician and Cantabrian coast in northern Spain. In total, 72 platyhelminth species are listed in this study. Forty‐two species represent new records for the Iberian Peninsula, three of which represent new genera records. A new species belonging to the genus Djeziraia (Polycystididae, Kalyptorhynchia), Djeziraia longistyla sp. nov., is described in this paper. In this broad‐scale study, a large data set (27 localities) of the estuaries of northern Spain allowed an analysis of the turbellarian species assemblages and the relation of species distributions to salinity, conductivity, oxygen, temperature, and sediment characteristics. Species assemblages (species diversity) of each habitat of the brackish water ecotone are shown. The present study contributes to knowledge on the ability of adaptation of free‐living Platyhelminthes to regimes of brackish water ecotones. 相似文献
107.
108.
《Journal of Natural History》2012,46(23):2109-2123
Three new species of marine nematodes belonging to the genera Paranticoma (family Anticomidae) and Parodontophora (family Axonolaimidae) are described from the Bohai Sea and Yellow Sea. Paranticoma tricerviseta sp. nov. is similar to P. bandaenseMicoletzky and Kreis, in the spicules, but can be distinguished by the presence of a ventral projection on the spicules, three regularly arranged cervical setae in both the male and female, and two distinct ventral setae behind the anus. Parodontophora deltensis sp. nov. is close to P. paragranulifera (Timm, ) in the length of the amphids, with the ventral arm of the amphid extending past the base of the stoma, but can be separated by the ratio of dorsal arm length to ventral arm (0.36–0.55 versus 0.20–0.25) and the position of the excretory pore (at the middle level versus top level of the stoma), distinctive cervical setae arrangement and a longer renette cell. Parodontophora wuleidaowanensis sp. nov. is close to P. danker Belogurov and Kartavtseva, in the form of the amphids, but can be distinguished by the longer length of the ventral arm of the amphids and the distinctive arrangement of cervical setae. 相似文献
109.
《Journal of Natural History》2012,46(3-4):157-176
Collecting in southern Spain yielded five species of Parotoplana and one species of Parotoplanella (Proseriata: Otoplanidae). Four species of Paratoplana proved to be new to science. Parotoplana cucullata sp. n. is distinguished by the shape of the lateral spines in the copulatory organ and in the presence of a “glandular organ” around the distal portion of the female duct. Parotoplana fretigaditani sp. n. is similar to P. procerostyla Ax, 1956 in the general arrangement of spines, but their fine morphology is distinctive. Parotoplana varispinosa sp. n. differs from P. capitata Ax, 1956 in the shape and number of spines. Parotoplana mastigophora sp. n. has a unique morphology of the stylet, and the spines of the girdle markedly differ in size and shape. The karyotype of P. cucullata sp. n. (n = 6) is described. In addition, Parotoplana primitiva and Parotoplanella heterorhabditica, previously known from the Atlantic coast of France and north‐west Mediterranean, respectively, were found. The high proportion of new species demonstrates the present poor state of knowledge of interstial meiofauna. 相似文献
110.
《Journal of Natural History》2012,46(33-36):2063-2079
Five species of the parasitic isopod genus Dactylokepon are described from brachyuran crabs and a scyllarid shrimp collected in Chinese waters. Four species are first recorded from this region, D. richardsonae Stebbing, 1910 infesting Portunus argentatus (White), D. semipennatus Bourdon, 1983 infesting Portunus haanii (Stimpson) and Lupocyclus rotundatus Adams and White, D. holthuisi Bourdon, 1967 infesting Eduarctus martensii (Pfeffer), and D. caribaeus Markham, 1975 infesting Randallia trituberculata Sakai. In addition, one species is new to science, D. barbuladigitus n. sp. infesting Liagore rubromaculata (De Haan). Six brachyuran crabs are reported for the first time as hosts of bopyrids. The new species is distinguished from other species of Dactylokepon in having a prominent trifid frontal lamina and a distinct digitate barbula. 相似文献