全文获取类型
收费全文 | 1835篇 |
免费 | 33篇 |
国内免费 | 34篇 |
专业分类
系统科学 | 33篇 |
丛书文集 | 35篇 |
教育与普及 | 11篇 |
理论与方法论 | 11篇 |
现状及发展 | 47篇 |
综合类 | 1626篇 |
自然研究 | 139篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 35篇 |
2014年 | 82篇 |
2013年 | 77篇 |
2012年 | 220篇 |
2011年 | 125篇 |
2010年 | 93篇 |
2009年 | 101篇 |
2008年 | 91篇 |
2007年 | 115篇 |
2006年 | 85篇 |
2005年 | 75篇 |
2004年 | 80篇 |
2003年 | 60篇 |
2002年 | 50篇 |
2001年 | 50篇 |
2000年 | 70篇 |
1999年 | 38篇 |
1998年 | 40篇 |
1997年 | 34篇 |
1996年 | 36篇 |
1995年 | 36篇 |
1994年 | 38篇 |
1993年 | 26篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 4篇 |
排序方式: 共有1902条查询结果,搜索用时 171 毫秒
91.
赵爱华 《华北科技学院学报》2010,7(3):27-29
分析了近阶段全国各地中小矿山发生的特殊"矿难事故"特点,从人员管理、法制宣传和安全监察等方面,探讨了新型矿难产生的原因,并基于安全生产中存在的问题,从矿山管理、法制宣传、管理改革等方面提出了相应措施。 相似文献
92.
93.
《Journal of Natural History》2012,46(9):1091-1154
The species of the Holarctic jumping spider genus Talavera are reviewed. Five new species are described: Talavera ikedai sp. n. (¦ §) from Japan and Korea; T. krocha sp. n. (¦ §) from France, Ukraine and Kyrghyzstan; T. parvistyla sp. n. (¦ §) from central and northern Europe; T. sharlaa sp. n. (§) from Tuva; and T. tuvensis sp. n. (¦) from Tuva. A lectotype is designated for Euophrys monticola Kulczy ` ski, 1884. A key to the 14 species now encompassed in this genus, and distributional maps, are provided for all of them. Arguments are given for placing the names Euophrys poecilopus Thorell, 1873 and Attus westringi Simon, 1868 as nomina dubia. Talavera aperta Miller, 1971 is removed from synonymy with both Talavera monticola (Kulczy ` ski, 1884) and Talavera thorelli (Kulczy ` ski, 1891). 相似文献
94.
《Journal of Natural History》2012,46(10):1517-1563
A total of 53 Amiota (s. str.) species (75% of the world total) from Asia and Europe, including 10 new species, kamui, kimurai and planata from Japan, and aristata, cuii, macai, magniflava, nuerhachii, spinata and watabei from China, are reviewed with designation of two new synonymies and phylogenetic analysis. Based upon the result of cladistic analysis with 31 adult male morphological characters, the following conclusions are deduced: (1) The subgenus Amiota is monophyletic, so far as the Asian and European forms are concerned. (2) Seven monophyletic groups are recognized within this subgenus. Two of them correspond to known species-groups, the apodemata and sinuata groups, and the remaining five are established as new species-groups, the nagatai, basdeni, taurusata, alboguttata and rufescens groups. A key to all the studied species from Asia and Europe is provided. 相似文献
95.
96.
新批评派在批评实践中通过文本细读,实际上是把作品放在封闭的圈子里,隔断它和文本生成的社会关系,过于纯粹,显得贫血。社会批判派,马克思主义的文学批评是其中的重要流派,强调文本所蕴含的社会价值,力图通过文本去认识社会,积极地社会批判;此派源远流长,具有强大的生命力,尤其是西方马克思主义者阿尔都塞的传唤理论,在传统的诗歌研究中具有借鉴意义,值得移植。 相似文献
97.
98.
报道了产自南昌的马钱科Loganiaceae尖帽草属Mitrasacme尖帽草Mitrasacme indica Wight,该种系江西首次发现。 相似文献
99.
《Journal of Natural History》2012,46(29-30):1761-1778
This paper introduces new data on Todaropsis eblanae morphology, morphometry and functional aspects of the male reproductive system and hectocotylus. Spermatophores differ in specimens from the Atlantic Ocean (average length, 18.28 ± 1.45 mm, 15.63 ± 0.8% of mantle length; weight, 2.0–12.0 mg) and the Indian Ocean (average length, 24.8 ± 2.85 mm, 16.9 ± 2.1% of mantle length; weight, 35.0–39.6 mg) (t?=?3.14; p < 0.01 for absolute sizes and t?=?0.711; p > 001 for relative sizes). An additional important distinctive trait is the form of connection of the cement body with the ejaculatory tube. In recent years, T. eblanae has been regularly caught in the Barents Sea, meaning its range has extended to subarctic waters. The morphology and morphometry of the spermatophoric complex of organs did not vary in investigated parts of its range. Hectocotylus patterns and some important spermatophore traits distinguish Todaropsis from other Ommastrephidae. 相似文献
100.
《Journal of Natural History》2012,46(7):1125-1133
Two new genera of the bryozoan family Calloporidae are described from New Zealand. The first, Leptinatella, is introduced for L. gordoni n. sp., specimens of which have been referred in the past to Watersia militaris (Waters) but are distinct from this species, which is a phase of the cribrimorph Corbulipora tubulifera (Hincks). The second genus, Bryocalyx, is introduced for B. cinnameus n. sp., which has small, conical colonies anchored by rhizoids. Another species of Bryocalyx is known from a few fragments only: and has also been referred in the past to Watersia sp. It is briefly discussed, but left unnamed here. 相似文献