全文获取类型
收费全文 | 11905篇 |
免费 | 955篇 |
国内免费 | 4篇 |
专业分类
12864篇 |
出版年
2023年 | 68篇 |
2022年 | 134篇 |
2021年 | 245篇 |
2020年 | 223篇 |
2019年 | 265篇 |
2018年 | 337篇 |
2017年 | 270篇 |
2016年 | 411篇 |
2015年 | 657篇 |
2014年 | 642篇 |
2013年 | 820篇 |
2012年 | 971篇 |
2011年 | 909篇 |
2010年 | 594篇 |
2009年 | 542篇 |
2008年 | 650篇 |
2007年 | 636篇 |
2006年 | 603篇 |
2005年 | 558篇 |
2004年 | 530篇 |
2003年 | 446篇 |
2002年 | 412篇 |
2001年 | 172篇 |
2000年 | 142篇 |
1999年 | 145篇 |
1998年 | 144篇 |
1997年 | 112篇 |
1996年 | 85篇 |
1995年 | 74篇 |
1994年 | 85篇 |
1993年 | 81篇 |
1992年 | 81篇 |
1991年 | 76篇 |
1990年 | 76篇 |
1989年 | 63篇 |
1988年 | 62篇 |
1987年 | 49篇 |
1986年 | 52篇 |
1985年 | 53篇 |
1984年 | 52篇 |
1983年 | 39篇 |
1982年 | 40篇 |
1981年 | 37篇 |
1980年 | 25篇 |
1979年 | 17篇 |
1978年 | 18篇 |
1977年 | 17篇 |
1976年 | 22篇 |
1975年 | 17篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
R. Borges-Argez L. Balnbury A. Flowers A. Gimnez-Turba G. Ruiz P.G. Waterman L.M. Pea-Rodríguez 《Phytomedicine》2007,14(7-8):530-533
A number of flavonoids isolated from Lonchocarpus spp. were evaluated for their antiprotozoal and cytotoxic activity. Flavone 6 and chalcone 7 were found to be the most active against Leishmania parasites and against cell cultures of Leukemia P388DI and adenocarcinoma prostate PC-3. 相似文献
3.
4.
Francisco Gutirrez‐Corchero M. Victoria Arruga Lourdes Sanz Cristina García M. Angeles Hernndez Francisco Campos 《Molecular ecology resources》2002,2(1):75-77
FTA® cards were used for long‐term storage of avian blood samples. Blood DNA was extracted by a simple method and used in PCR for sex identification of adult and nestling Great Grey Shrikes Lanius excubitor. 相似文献
5.
6.
7.
P. Cruz C. H. Mejia‐Ruiz R. Perez‐Enriquez A. M. Ibarra 《Molecular ecology resources》2002,2(3):239-241
Five polymorphic microsatellite loci were characterized for Penaeus (Litopenaeus) vannamei. Loci were isolated using a partial Sau3A1 genomic library by the sequencing of randomly selected clones and by a biotinylated (CT)10 and (GT)10 probes screening procedure. The last strategy resulted in the most useful data. About 40% of the clones showed a previously reported satellite/microsatellite (PVS1), reducing the chance of finding new microsatellite regions. Whereas two of the microsatellite loci with more than 10 alleles will be useful for mating analysis in a breeding program, the others might prove useful for population genetic studies. 相似文献
8.
Francisco E. Fontúrbel 《Mammalian Biology》2010,75(4):294-301
Assessing small mammal diversity is a common procedure, which usually employs widespread standard techniques, for gathering information for a wide range of studies. Traditional methods, however, may be biased against capturing arboreal marsupials, such as Dromiciops gliroides, an endemic marsupial currently considered a rare species in the Patagonian temperate rainforest due to the low abundances reported previously. I tested a new capturing methodology to assess the small mammal diversity of an old-growth forest in Patagonia, based on a randomized and balanced design, which incorporated a combination of different trap types, bait types, and placement heights. The proposed methodology included four trap types (two for live-capturing: wire-mesh and Sherman traps, and two sign-recording traps for tracks and hair), two types of bait (banana and rolled oats), and two trap placements (ground level and 1.5–2.5 m above the ground). Trap type, bait type, and height of placement all had significantly different effects on capturing and detecting rodents or marsupials; environmental variables at the trap location also affected the ability to detect rodents and marsupials. Traditional methods used for sampling small mammals performed well for rodents but are not effective for capturing marsupials and vice versa, showing species-specific sampling protocols. There is no single combination of trap-bait-height capable to assess the entire small mammal community, but the combination of the most effective protocol for rodents and the most effective protocol for marsupials guarantee better results. 相似文献
9.
10.
Fabián Michelangeli Dalia M. Sulcas Marie-Christine Ruiz 《Cell and tissue research》1987,250(2):413-419
Summary This study is concerned with electron-microscopic observations on endocrine or paracrine cells in the fundic gastric mucosa of the bullfrog. Also, an attempt was made to identify the histamine-releasing cells involved in the secretagogue response. At least three distinct endocrine-like cell types were found. The classification is based on the appearance of secretory granules and other organelles, and the relationship of endocrine-like cells with other cells in the tissue. The amphibian endocrine-like cells resemble the ECL, D and EC cells of mammals. Type-I (ECL) cells showed degranulation after repeated stimulation with tetragastrin (TG), acetylcholine (ACh) and K+ depolarizing solution, all of which release histamine. 相似文献