全文获取类型
收费全文 | 1128篇 |
免费 | 36篇 |
国内免费 | 65篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 10篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 24篇 |
2018年 | 34篇 |
2017年 | 20篇 |
2016年 | 60篇 |
2015年 | 227篇 |
2014年 | 109篇 |
2013年 | 67篇 |
2012年 | 51篇 |
2011年 | 40篇 |
2010年 | 33篇 |
2009年 | 34篇 |
2008年 | 32篇 |
2007年 | 45篇 |
2006年 | 41篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 21篇 |
2002年 | 31篇 |
2001年 | 25篇 |
2000年 | 18篇 |
1999年 | 24篇 |
1998年 | 27篇 |
1997年 | 26篇 |
1996年 | 21篇 |
1995年 | 25篇 |
1994年 | 18篇 |
1993年 | 7篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1229条查询结果,搜索用时 15 毫秒
991.
Christian Lukhaup 《ZooKeys》2015,(502):1-10
A new species, Cherax (Astaconephrops) pulcher
sp. n., from Hoa Creek, close to the village Teminabuan in the southern-central part of the Kepala Burung (Vogelkop) Peninsula, West Papua, Indonesia, is described, figured and compared with the morphologically closest species, Cherax
boesemani Lukhaup & Pekny, 2008. 相似文献
992.
The millipede genus Kronopolites currently comprises 11 species, including a new species from northern Laos: Kronopolites
lunatus
sp. n. The generic diagnosis is updated, a key given to all known species, and their distributions are mapped. 相似文献
993.
Among polychaetes, polynoids have the highest number of symbiotic species found living with a wide variety of marine invertebrates, including other polychaetes. Lepidasthenia Malmgren, 1867 and Lepidametria Webster, 1879 were regarded as synonyms but belong to different subfamilies, although both have species associated with thelepodid or terebellid polychaetes. In this contribution Lepidasthenia
loboi
sp. n. is described from several specimens associated with the thelepodid Thelepus
antarcticus Kinberg, 1867, collected on a rocky shore near Puerto Madryn, Argentina. Lepidasthenia
loboi
sp. n. can be confused with Lepidasthenia
esbelta Amaral & Nonato, 1982 because both live with Thelepus, are of similar sizes with similar pigmentation patterns, and have giant neurochaetae. However, in Lepidasthenia
loboi
sp. n. all eyes are of the same size, cephalic and parapodial cirri are tapered and mucronate, the second pair of elytra is larger than the third, the ventral cirri arise at the base of parapodia such that they do not reach chaetal lobe tips, and neuraciculae are tapered. On the contrary, in Lepidasthenia
esbelta the posterior eyes are larger than anterior ones, cephalic and parapodial appendages are swollen subdistally, the second and third pairs of elytra are of the same size, the ventral cirri arise medially such that their tips reach the neurochaetal lobe tips, and the neuraciculae have falcate tips. Some comments about other genera in the Lepidastheniinae, a simplified key to its genera, and a key to Lepidasthenia species with giant neurochaetae are also included. 相似文献
994.
Sergio álvarez-Ortega Thi Anh Duong Nguyen Joaquín Abolafia Thi Thanh Tam Vu Reyes Pe?a-Santiago 《ZooKeys》2015,(516):1-26
Three new species of Aporcelaimoides from natural habitats in Vietnam are studied, described and illustrated, including line drawings, LM and/or SEM pictures. Aporcelaimoides
brevistylum
sp. n. is characterized by its body 1.95–2.90 mm long, lip region offset by deep constriction and 17–18 µm broad, ventral side of mural odontostyle 11–14 µm long with aperture occupying 62–71% of its length, neck 663–767 µm long, pharyngeal expansion occupying 58–66% of total neck length, uterus a simple tube 85–182 µm long, pars refringens vaginae absent, V = 55–63, tail short and rounded (34–46 µm, c = 49–76, c’ = 0.6–0.8), spicules 67–86 µm long, and one ventromedian supplement out the range of spicules. Aporcelaimoides
minor
sp. n. is distinguished in having body 2.09–2.61 mm long, lip region offset by deep constriction and 19–20 µm broad, mural odontostyle 14–16 µm long at its ventral side with aperture occupying 73–84% of its length, neck 579–649 µm long, pharyngeal expansion occupying 57–66% of total neck length, uterus a simple tube 44–69 µm long, pars refringens vaginae well developed, V = 48–56, female tail very short, rounded conoid or truncate (14–26 µm, c = 90–146, c’ = 0.3–0.6), and male unknown. Aporcelaimoides
silvaticum
sp. n. is characterized by its body 2.09–2.60 mm long, lip region offset by depression and 17–18 µm broad, mural odontostyle 11–12 µm long at its ventral side with aperture occupying 60–66% of its length, neck 597–720 µm long, pharyngeal expansion occupying 58–64% of total neck length, uterus a simple tube 128–243 µm long, pars refringens vaginae well developed, V = 58–60, tail short and rounded (27–37 µm, c = 67–94, c’ = 0.6–0.7), spicules 64–75 µm long, and two or three widely spaced ventromedian supplements bearing hiatus. The genus Aporcelaimoides is restored, its diagnosis emended, and three species of Sectonema, namely Sectonema
amazonicum, Sectonema
haguei and Sectonema
moderatum, transferred to it. An updated list of its species, a key to their identification and a tabular compendium with the most important morphometric features are also presented. 相似文献
995.
Three new species of Mycetophilidae – Cordyla
monticola
sp. n., Cordyla
pseudopusilla
sp. n. and Cordyla
reducta
sp. n. – are described from the Colombian Andes, representing the first described species of Cordyla Meigen from the Neotropical region. Colour photos of their habitus, wing and terminalia are provided. The morphological affinities of male terminalia are discussed in a worldwide context. The distributional pattern of the genus clearly indicates a case of northern elements reaching the north-western region of the Neotropics that corresponds to a secondary extension of a Holarctic clade to the south. 相似文献
996.
异极衣纲Lichinomycetes仅含异极衣目Lichinales,异极衣目内含3科:球蜂窝衣科Gloeoheppiaceae、异极衣科Lichinaceae和盾衣科Peltulaceae。本文基于表型特征对中国异极衣纲地衣分类研究发现新种1个:近叉指盾链衣Digitothyrea subdivergens,中国新记录属1个:指盾链衣属Digitothyrea,中国新记录种3个:白棋盘蜂窝衣Heppia solorinoides、朝氏盾链衣Thyrea asahinae和吉拉氏盾链衣Thyrea girardii,与形态相似种进行了比较和讨论。本研究不仅为中国地衣志的编研积累资料,同时为开展利用地衣结皮实施“沙漠生物地毯工程”储备资源信息。 相似文献
997.
罗霄山脉种子植物区系非常丰富, 是连接华东、华南、华中植物区系的重要通道, 区系组成具有明显的古老性和过渡性特征。本文针对该区域种子植物的特有现象和残遗现象, 分析了其组成特点及形成原因。结果表明: (1)罗霄山脉共有中国特有科3科, 特有属55属, 特有种1,624种, 罗霄山脉区域特有种43种7变种; 特有属中以古特有属为主, 并以温带成分占优势(达55.91%), 体现出明显的古老性和孑遗性。(2)罗霄山脉共有孑遗属165属, 以热带亚洲分布、东亚-北美间断分布、东亚特有及中国特有成分为主, 包括木本属132属。(3)受中新世气候波动以及第四纪冰期的影响, 许多北方热带植物群的常绿成分、北极-第三纪的落叶成分, 在罗霄山脉得以保存下来成为古特有和孑遗成分。特有现象、残遗现象的分析结果表明罗霄山脉是一个重要的生物避难所, 其对中国东部植物区系的保存和重新扩散具有重要意义。 相似文献
998.
Cormopsocidae n. fam . of the psocid suborder Trogiomorpha was proposed for a fossil species from mid‐Cretaceous Burmese amber, Cormopsocus groehni n. gen . & n. sp . This family was estimated to be the sister group of all other trogiomorphan taxa, but the possibility of much deeper divergence (i.e. placement as a sister group of all Psocodea) could not be excluded. Cormopsocus groehni retains many plesiomorphic features, which will contribute greatly to elucidating the ancestral state of Psocodea. 相似文献
999.
Balechina and the new genus Cucumeridinium gen. nov. (Dinophyceae), unarmored dinoflagellates with thick cell coverings 下载免费PDF全文
Fernando Gómez Purificación López‐García Haruyoshi Takayama David Moreira 《Journal of phycology》2015,51(6):1088-1105
The genus Balechina (=subgenus Pachydinium) was established for heterotrophic gymnodinioid dinoflagellates with a thick cell covering. The type species, B. pachydermata (=Gymnodinium pachyderm‐atum), showed numerous fine longitudinal striae, whereas B. coerulea (=G. coeruleum) showed ~24 prominent longitudinal surface ridges or furrows and a distinctive blue pigmentation. We have investigated the morphology and molecular phylogeny of these taxa and the species Gymnodinium cucumis, G. lira and G. amphora from the western Mediterranean, Brazil and Japan. Sudden contractions at the cingulum level were seen in B. pachydermata, which also showed a high morphological variability which included morphotypes that have been described as Amphidinium vasculum, G. amphora, G. dogielii and G. gracile sensu Kofoid and Swezy. Molecular phylogeny based on small subunit rRNA gene sequences revealed that Balechina coerulea, G. cucumis and G. lira formed a clade distantly related to the clade of the type species, B. pachydermata, and G. amphora. We propose the new genus Cucumeridinium for the species with longitudinal ridges and a circular apical groove (Cucumeridinium coeruleum comb. nov., C. lira comb. nov. and C. cucumis comb. nov.), and Gymnodinium canus and G. costatum are considered synonyms of C. coeruleum. The genus Balechina remains for the species with a double‐layer cell covering, bossed surface with fine striae, and an elongated elliptical apical groove. At present, the genus is monotypic containing only B. pachydermata. 相似文献
1000.
Multilocus phylogeny and a new classification for Southeast Asian and Melanesian forest frogs (family Ceratobatrachidae) 下载免费PDF全文
Rafe M. Brown Cameron D. Siler Stephen J. Richards Arvin C. Diesmos David C. Cannatella 《Zoological Journal of the Linnean Society》2015,174(1):130-168
We present a near comprehensive, densely sampled, multilocus phylogenetic estimate of species relationships within the anuran family Ceratobatrachidae, a morphologically and ecologically diverse group of frogs from the island archipelagos of Southeast Asia and the South‐West Pacific. Ceratobatrachid frogs consist of three clades: a small clade of enigmatic, primarily high‐elevation, semi‐aquatic Sundaland species currently assigned to Ingerana (for which we erect a new genus), which is the sister taxon of two large, monophyletic radiations, each situated on islands on either side of Wallace's Line. One radiation is composed of Philippine species of Platymantis and the other contains all taxa from the eastern Indonesian, New Guinean, Solomon, Bismarck, and Fijian archipelagos. Several additional genera (Batrachylodes, Discodeles, Ceratobatrachus, and Palmatorappia) are nested within Platymantis, and of these Batrachylodes and Discodeles are nonmonophyletic. To address the widespread paraphyly of the genus Platymantis and several additional nomenclatural issues, we undertook a wholesale nomenclatural reorganization of the family. Given our partially unresolved phylogeny, and in order to impart a conservative, stable taxonomy, involving a minimal number of genus‐species couplet changes, we propose a conservative classification representing a few compromises. These changes are designed to preserve maximally the presumed original intent of taxonomy (widely used group names associated with morphological and ecological diversity of particular species or groups of species) while implementing a hierarchical system that is consistent with the estimate of phylogeny based on new molecular data. © 2015 The Linnean Society of London 相似文献