首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3370篇
  免费   156篇
  国内免费   91篇
系统科学   41篇
丛书文集   76篇
教育与普及   14篇
理论与方法论   14篇
现状及发展   56篇
综合类   2767篇
自然研究   649篇
  2024年   9篇
  2023年   16篇
  2022年   32篇
  2021年   27篇
  2020年   58篇
  2019年   54篇
  2018年   60篇
  2017年   75篇
  2016年   58篇
  2015年   97篇
  2014年   116篇
  2013年   106篇
  2012年   674篇
  2011年   165篇
  2010年   146篇
  2009年   147篇
  2008年   130篇
  2007年   171篇
  2006年   153篇
  2005年   116篇
  2004年   125篇
  2003年   119篇
  2002年   93篇
  2001年   96篇
  2000年   90篇
  1999年   85篇
  1998年   75篇
  1997年   78篇
  1996年   50篇
  1995年   52篇
  1994年   74篇
  1993年   69篇
  1992年   45篇
  1991年   45篇
  1990年   29篇
  1989年   30篇
  1988年   18篇
  1987年   14篇
  1986年   8篇
  1985年   9篇
  1984年   2篇
  1982年   1篇
排序方式: 共有3617条查询结果,搜索用时 15 毫秒
31.
《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 Stebbing, T. R. R. 1906. Amphipoda 1: Gammaridea.. Das Tierreich, 21: 1806.  [Google Scholar]; 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   
32.
33.
《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   
34.
35.
《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   
36.
《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 Ax, P. 1956. Monographie der Otoplanidae (Turbellaria): morphologie und systematik.. Akademie der Wissenschaften und der literatur Abhandlungen der Mathematisch‐Naturwissenschaftlichen klasse, 13: 159278.  [Google Scholar] in the general arrangement of spines, but their fine morphology is distinctive. Parotoplana varispinosa sp. n. differs from P. capitata Ax, 1956 Ax, P. 1956. Monographie der Otoplanidae (Turbellaria): morphologie und systematik.. Akademie der Wissenschaften und der literatur Abhandlungen der Mathematisch‐Naturwissenschaftlichen klasse, 13: 159278.  [Google Scholar] 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   
37.
《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 Stebbing, T. R. R. 1910. Isopod from the Indian Ocean and British East Africa.. Reports of the Percy Sladen Trust Expedition to the Indian Ocean in 1905, under the leadership of Mr. J. Stanley Gardiner, M. A. Transactions of the Linnean Society of London, Series 2, Zoology, 14(1): 83122.  [Google Scholar] infesting Portunus argentatus (White), D. semipennatus Bourdon, 1983 Bourdon, R. 1983. Expédition Rumphius II (1975) Crustacés parasites, commensaux, etc. (Th. Monod éd.). VIII. Crustacés isopodes (3e partie: Épicarides Bopyridae).. Bulletin du Muséum National d'Histoire Naturelle, Paris, Série 4, 5(A3): 845869.  [Google Scholar] infesting Portunus haanii (Stimpson) and Lupocyclus rotundatus Adams and White, D. holthuisi Bourdon, 1967 Bourdon, R. 1967. Sur deux nouveaux épicarides (Isopoda) parasites de crustacés decapods.. Zoologische Mededelingen, 42(17): 167174.  [Google Scholar] infesting Eduarctus martensii (Pfeffer), and D. caribaeus Markham, 1975 Markham, J. C. 1975. New records of two species of parasitic isopods of the bopyrid subfamily Ioninae in the western Atlantic.. Crustaceana, 29(1): 5567.  [Google Scholar] 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   
38.
《Journal of Natural History》2012,46(21-24):1301-1311
The Australian members of the subgenus, Sinella (Coecobrya) Yosii, are revised. A new species from Western Australia, Queensland, and the Northern Territory, Sinella (Coecobrya) tropicalis sp. nov., is described, Sinella (Coecobrya) tenebricosa Folsom, 1902 is recorded from Australia for the first time, and new records of Sinella (Coecobrya) communis Chen and Christiansen, 1997 Chen, J‐X. and Christiansen, K. A. 1997. Subgenus Coecobrya of the genus Sinella (Collembola: Entomobryidae) with special reference to the species of China.. Annals of the American Society of Entomology, 90: 119.  [Google Scholar] are documented. Sinella (Coecobrya) caeca Schött, 1896 is considered a dubious record from Australia. A key is provided to the three known Australian species and a summary given of all dorsal and lateral chaetal patterns found on the fourth abdominal segment of subgenera Sinella Brook, 1882 Brook, G. 1882. On a new genus of Collembola (Sinella) allied to Degeeria Nicolet.. Journal of the Linnean Society of London (Zoology), 16: 541545.  [Google Scholar] and Coecobrya Yosii, 1956 Yosii, R. 1956. Hohlencollembolen Japans II.. Japanese Journal of Zoology, 11(5): 609627.  [Google Scholar]. The biogeography of the subgenus is described.  相似文献   
39.
《Journal of Natural History》2012,46(17-18):1093-1114
The present study reports on collections of hypogean freshwater atyid shrimps of the genera Caridina Milne Edwards, 1837 Milne Edwards, H. 1837. Histoire naturalle des Crustacés, Comprenant l'Anatomie, la Physiologie et la Classification de ces Animaux, Vol. 2, 1532. Paris (France): Libraire Encyclopedique de Roret.  [Google Scholar], and Parisia Holthuis, 1956 Holthuis, L. B. 1956. The troglobic Atyidae of Madagascar (Crudtacea, Decapoda, Natantia), Mem Inst Sci Madagascar ser.. A., 11: 97110.  [Google Scholar], obtained from the karst caves and associated epigean waters of Sulawesi, Indonesia. Six species of Caridina were present, of which two are new to science and one is new to Sulawesi, as well as one new species of Parisia. Types of Caridina pareparensis De Man, 1892 De Man, J. G. 1892. Decapoden des Indischen Archipels.. Zool Ergebn Reise Niederland Ost‐Ind., 2: 265527. pl. 15–29 [Google Scholar], and C. pareparensis parvidentata Roux, 1904 Roux, J. 1904. Décapodes d'eau douce de Cèlébes (Genres Caridina et Potamon).. Rev Suisse Zool., 12(3): 539572. pl. 9 [Google Scholar], were re‐examined and redescribed; lectotypes for both taxa are designated. Caridina pareparensis parvidentata is here regarded as a distinct species. The new taxa are described, figured and compared with congeners.  相似文献   
40.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号