全文获取类型
收费全文 | 294篇 |
免费 | 45篇 |
国内免费 | 108篇 |
出版年
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 23篇 |
2013年 | 22篇 |
2012年 | 23篇 |
2011年 | 22篇 |
2010年 | 16篇 |
2009年 | 28篇 |
2008年 | 17篇 |
2007年 | 22篇 |
2006年 | 26篇 |
2005年 | 23篇 |
2004年 | 21篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 19篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 8篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1977年 | 1篇 |
排序方式: 共有447条查询结果,搜索用时 15 毫秒
1.
2.
TAKEHIKO Y. ITO AYUMI OKADA BAYARBAATAR BUUVEIBAATAR BADAMJAV LHAGVASUREN SEIKI TAKATSUKI ATSUSHI TSUNEKAWA 《The Journal of wildlife management》2008,72(4):940-943
Abstract: We conducted a carcass census of Mongolian gazelles (Procapra gutturosa) along the Trans-Mongolian railroad in June 2005. We counted 241 gazelles that had died within the previous 12 months. Carcass numbers were greater on the southwestern side in the northern 3 zones, but we found carcasses only on the northeastern side in the southernmost zone. It suggests that impact of the railroad was stronger on one side and that the strength of this impact varied among regions. 相似文献
3.
4.
The spectra of k-mer frequencies can reveal the structures and evolution of genome sequences. We confirmed that the trimodal spectrum of 8-mers in human genome sequences is distinguished only by CG2, CG1 and CG0 8-mer sets, containing 2,1 or 0 CpG, respectively. This phenomenon is called independent selection law. The three types of CG 8-mers were considered as different functional elements. We conjectured that (1) nucleosome binding motifs are mainly characterized by CG1 8-mers and (2) the core structural units of CpG island sequences are predominantly characterized by CG2 8-mers. To validate our conjectures, nucleosome occupied sequences and CGI sequences were extracted, then the sequence parameters were constructed through the information of the three CG 8-mer sets respectively. ROC analysis showed that CG1 8-mers are more preference in nucleosome occupied segments (AUC > 0.7) and CG2 8-mers are more preference in CGI sequences (AUC > 0.99). This validates our conjecture in principle. 相似文献
5.
6.
Seasonal variation in oxygen isotope composition of waters for a montane larch forest in Mongolia 总被引:2,自引:0,他引:2
Sheng-Gong Li Maki Tsujimura Atsuko Sugimoto Lisa Sasaki Tsutomu Yamanaka Gombo Davaa Dambaravjaa Oyunbaatar Michiaki Sugita 《Trees - Structure and Function》2006,20(1):122-130
Measurements of water oxygen isotopic composition were conducted in the 2003 growing season for a montane larch (Larix sibirica Ledeb.) forest in northern Mongolia, a transitional area from the south Siberian taiga to the Asian steppe. Oxygen isotopic
composition of foliar water and its daily variability were found to be sensitive to atmospheric evaporative demand. During
most of the growing season, water sources used by larch trees were from the upper 30-cm surface layer of the soil when precipitation
input was large, and were from the deeper layer when the water supply at the upper soil layer was limited. The Keeling plot
method suggested that the forest returned soil water to the atmosphere predominantly by means of canopy transpiration during
the peak growth period (in August). 相似文献
7.
8.
Lasiosynidae n. fam. is proposed for the genera Lasiosyne Tan, Ren & Chih 2007 (transferred from Archostemata to Polyphaga), Anacapitis Yan 2009 Tarsomegamerus Zhang 2005 (proposed in the superfamily Chrysomeloidea) and Bupredactyla n. gen. The new family is regarded in composition of the infraorder Elateriformia without a more detailed attribution, because it demonstrates a mixture of characters of different families and superfamilies, i.e. somehow an intermediate position between the superfamilies Dascilloidea, Elateroidea, Buprestoidea and Byrrhoidea with most resemblance to Dascillidae, Schizopodidae, Eulichadidae, Ptilodactylidae and Callirrhipidae and probable more close relationship to the last three families. Four new fossil species of the genus Lasiosyne: L. daohugouensis n. sp., L. fedorenkoi n. sp., L. gratiosa n. sp., L. quadricollis n. sp., and also Bupredactyla magna n. sp. are described from the Middle Jurassic Jiulongshan Formation of eastern Inner Mongolia, China. A probable generic composition of the new family is considered. The synonymy of generic names Anacapitis Yan 2009 and Brachysyne Tan & Ren 2009, n. syn. as well as synonymy of species names Lasiosyne euglyphea Tan, Ren & Chih 2007, Pappisyne eucallus Tan & Ren 2009, n. syn. and Pappisyne spathulata Tan & Ren 2009, n. syn. are proposed. 相似文献
9.
Abstract: Two new genera with six new species of hangingflies (Mecoptera: Raptipedia: Cimbrophlebiidae) are described. They were collected from the Middle Jurassic nonmarine sedimentary strata of the Jiulongshan Formation in Daohugou, Inner Mongolia, north‐eastern China. This report of Cimbrophlebiidae from the Yanliao Biota provides detailed morphological information and evidence of a broad diversity of Cimbrophlebiidae during the Middle Jurassic. A key to the known species of Cimbrophlebiidae is provided. 相似文献
10.
气候变化对内蒙古中部草原优势牧草生长季的影响 总被引:1,自引:0,他引:1
研究温性典型草原优势牧草生长季与气候因子变化的关系,对于监测草地环境变化及保护利用,评估区域气候变化对优势牧草生长的影响,指导畜牧业生产等具有重要的科学意义和实践价值.基于内蒙古中部草原3个牧业气象试验站1983-2009年克氏针茅和羊草的物候期、气象资料,对返青、黄枯日期、生长季与气温、降水量之间的关系进行了统计分析.结果表明:(1)27a间,该区的年、春季、夏季和秋季平均气温均呈显著升高趋势,春季升温幅度最大,气候倾向率为0.71-0.84℃/10a;各时段降水量变化除春季呈微量增加趋势外,总体呈减少态势.可见,内蒙古中部温性典型草原区暖干化趋势明显.(2)27a间,锡林浩特克氏针茅和羊草返青日期表现为推后趋势,并与4月降水量呈显著正相关;镶黄旗和察右后旗克氏针茅和羊草返青日期呈提前趋势,并与3-5月气温、降水量呈显著负相关,气温每升高1℃、降水量每增加10mm,优势牧草返青日期约提前3.0-5.1d和1.3-2.1d.(3)该区克氏针茅和羊草黄枯日期均呈提前趋势,与8-9月气温均呈显著负相关,降水量为正相关,气温每升高1℃,克氏针茅黄枯日期提前1.7-10.7 d,羊草黄枯日期提前3.5-11.3d,降水量的影响相对较弱.(4)该区克氏针茅生长季延长趋势明显,羊草生长季缩短趋势明显.克氏针茅生长季与4-10月均温正相关系数最大,羊草生长季与水热系数的正相关系数最大. 相似文献