全文获取类型
收费全文 | 9375篇 |
免费 | 221篇 |
国内免费 | 855篇 |
出版年
2024年 | 21篇 |
2023年 | 67篇 |
2022年 | 94篇 |
2021年 | 117篇 |
2020年 | 134篇 |
2019年 | 179篇 |
2018年 | 166篇 |
2017年 | 149篇 |
2016年 | 291篇 |
2015年 | 409篇 |
2014年 | 446篇 |
2013年 | 735篇 |
2012年 | 558篇 |
2011年 | 505篇 |
2010年 | 302篇 |
2009年 | 417篇 |
2008年 | 450篇 |
2007年 | 453篇 |
2006年 | 404篇 |
2005年 | 362篇 |
2004年 | 330篇 |
2003年 | 354篇 |
2002年 | 384篇 |
2001年 | 278篇 |
2000年 | 271篇 |
1999年 | 225篇 |
1998年 | 203篇 |
1997年 | 212篇 |
1996年 | 222篇 |
1995年 | 260篇 |
1994年 | 185篇 |
1993年 | 129篇 |
1992年 | 145篇 |
1991年 | 125篇 |
1990年 | 137篇 |
1989年 | 104篇 |
1988年 | 22篇 |
1987年 | 24篇 |
1986年 | 26篇 |
1985年 | 33篇 |
1984年 | 38篇 |
1983年 | 20篇 |
1982年 | 45篇 |
1981年 | 50篇 |
1980年 | 100篇 |
1979年 | 114篇 |
1978年 | 60篇 |
1977年 | 38篇 |
1976年 | 15篇 |
1974年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Morphology of the first instar larvae of Collembola has considerably taxonomical and phylogenetic significance. We describe the first instar larvae for the first time in Homidia. External morphology of first instar larvae and adults of Homidia jordanai sp. n. is described based on observations under light and scanning electron microscopes. Most organs of adults bear considerably more setae than the first instar larvae; in addition, first instar larval Homidia lack labial seta R, seta on tenaculum, mucronal spine, and dental spines. The new species is characterized by weakly pigmented body, long antennae subequal to body in length, 1+1 inner macrochaetae on Abd. III, few inner macrochaetae on posterior Abd. IV, and spiny and short seta pi on dental base. Differences between new species and other two similar ones, taxonomical significance of the first instar larvae and the position of Homidia are also discussed. 相似文献
912.
The cantharid Fissocantharis semifumata species-groupis reviewed. Fissocantharis semifumata (Fairmaire, 1889) is redescribed and illustrated. The type series of Fissocantharis fissa (Wittmer, 1997) is shown to consist of 3 species and clarified, except the holotype, the two paratypes become invalid. Fissocantharis grahami (Wittmer, 1997) is attributed to this species group. Six new species are described and illustrated, Fissocanthais yuisp. n. (CHINA: Yunnan), Fissocantharis semimetallicasp. n. (CHINA: Yunnan; MYANMAR: Kachin), Fissocantharis bicoloratasp. n. (CHINA: Sichuan), Fissocantharis maculicepssp. n. (CHINA: Gansu), Fissocantharis bimaculatasp. n. (CHINA: Sichuan) and Fissocantharis flavasp. n. (CHINA: Sichuan, Guizhou). The number of species in the Fissocantharis semifumata species-groupis increased from 4 to 11, and a key to all species is provided. 相似文献
913.
A new species of the cleptoparasitic bee genus Microsphecodes Eickwort and Stage (Halictinae: Halictini) is described and figured from a male and female collected in Jamaica. Microsphecodes xaymacensis Engel, sp. n., is distinguished from its congeners on the basis of integumental coloration and sculpturing, and form of the male pygidial plate and genitalia. 相似文献
914.
Palpostilpnus brevis Sheng & Broad, sp.n., belonging to the tribe Phygadeuontini of the subfamily Cryptinae (Hymenoptera, Ichneumonidae), collected from Jiangxi Province, China, is described. A key to the described species of the genus Palpostilpnus Aubert, 1961, is provided. 相似文献
915.
Bennett DJ 《ZooKeys》2011,(141):65-70
A distinctive new species of the crabronine wasp genus Quexua Pate is described and figured from a single male collected from lowland Amazonian rain forest in southeastern Peru. Quexua cicrasp. n. is the only species in the genus known with a sessile metasoma. 相似文献
916.
917.
Anichtchenko A 《ZooKeys》2011,(155):1-50
Species of the genus Singilis Rambur, 1837 (Phloeozeteus Peyron, 1856, syn. n., Agatus Motschulsky, 1845, syn. n.), occurring in the Middle East and Central Asia are reviewed, with 24 species now recognized in the region, including ten species described as new: Singilis makarovi sp. n. (Tajikistan), Singilis jedlickai sp. n. (Afghanistan), Singilis kolesnichenkoi sp. n. (Iran), Singilis kabakovi sp. n. (Afghanistan, Iran), Singilis timuri sp. n. (Uzbekistan), Singilis klimenkoi sp. n. (Iran), Singilis saeedi sp. n. (Iran), Singilis felixi sp. n. (UAE), Singilis kryzhanovskii sp. n. (Iran, Turkmenistan), and Singilis timidus sp. n. (Iran); Singilis libani (Sahlberg, 1913) is recognized as a valid species; and Singilis solskyi nom. n. is proposed as a replacement name for Agatus bicolor (Solsky, 1874, not Rambur 1837), now placed in Singilis as junior homonym. New synonymies include: Singilis cingulatus (Gebler, 1843) = Singilis jakeschi Jedlička, 1967, syn. n.; Singilis mesopotamicus Pic, 1901 = Singilis apicalis Jedlička, 1956, syn. n. A key to species is provided. Habitus and aedeagal illustrations are provided for all species. Distributional data include many new country records. 相似文献
918.
New hexactinellid sponges were collected from 2589 m depth on the Carlsberg Ridge in the Indian Ocean during deep-sea dredging. All fragments belong to a new genus and species, Indiellagen. n.ridgenensissp. n., a representative of the family Aulocalycidae described here. The peculiar features of this sponge, not described earlier for other Aulocalycidae, are: longitudinal strands present in several layers and epirhyses channelization. 相似文献
919.
A new monotypic genus of Naupactini (Coleoptera: Curculionidae), Obrieniolus del Río is described based on the new species Obrieniolus robustus del Río, endemic to Peru. This genus is easily recognized by the black, denuded and shiny integument, with imbricate microsculpture and the rounded body, with short, cordiform and moderately convex elytra. According to a cladistic analysis based on 69 continuous and discrete morphological characters, the new genus is the sister taxon of a group formed by Amitrus Schoenherr, Trichocyphus Heller, Amphideritus Schoenherr, Asymmathetes Wibmer & O'Brien and Galapaganus Lanteri. The paper includes habitus photographs, line drawings of genitalia, mouthparts, and other external features of taxonomic value, and a dichotomous key to the genera of Naupactini distributed in the South American Transition Zone. 相似文献
920.
Dubinectes infirmussp. n., Munnopsidae, is described from the Argentine Basin, southwest Atlantic, at depths between 4586-4607 m. The new species is distinguished by a narrow rim of the pleotelson posterior margin which is not raising over its dorsal surface; article 3 of the antennula is subequal in length to article 2; distomedial lobes of male pleopod 1 are of same size as distolateral lobes; stylet of male pleopod 2 is subequal in length to protopod; uropod exopod is more than a half of endopod length. Some generic characters which are weakly pronounced in the new species or have different state are defined more precisely in the revised diagnosis of Dubinectes. The modified diagnosis of the genus, a key to the species of Dubinectes as well as the distribution of the genus are presented. 相似文献