全文获取类型
收费全文 | 1411篇 |
免费 | 84篇 |
国内免费 | 70篇 |
出版年
2024年 | 2篇 |
2023年 | 22篇 |
2022年 | 32篇 |
2021年 | 65篇 |
2020年 | 46篇 |
2019年 | 67篇 |
2018年 | 48篇 |
2017年 | 52篇 |
2016年 | 40篇 |
2015年 | 33篇 |
2014年 | 47篇 |
2013年 | 96篇 |
2012年 | 36篇 |
2011年 | 41篇 |
2010年 | 36篇 |
2009年 | 80篇 |
2008年 | 62篇 |
2007年 | 75篇 |
2006年 | 63篇 |
2005年 | 42篇 |
2004年 | 42篇 |
2003年 | 43篇 |
2002年 | 54篇 |
2001年 | 32篇 |
2000年 | 26篇 |
1999年 | 33篇 |
1998年 | 34篇 |
1997年 | 31篇 |
1996年 | 21篇 |
1995年 | 24篇 |
1994年 | 35篇 |
1993年 | 27篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 13篇 |
1987年 | 12篇 |
1986年 | 6篇 |
1985年 | 23篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有1565条查询结果,搜索用时 248 毫秒
221.
222.
Embryogenic cell suspension cultures were obtained from calli developed from mature rice seeds of a Japonica type Itahan cultivar, Roncarolo. Protoplasts were isolated and transformed by PEG-treated method with plasmid pHP23 carrying the NPT Ⅱ gene which encodes resistance to antibiotic G-418. Protoplast-derived colonies were selected in presence of the inhibitor. Plants were regenerated and transplanted into soil in the green house. The presence of foreign gene in the regenerated plants was verified by PCR and Southern analysis. 相似文献
223.
224.
225.
《Saudi Journal of Biological Sciences》2021,28(11):6112-6115
Fibroblast growth factor receptor 2 is a protein encoded by FGFR2 gene and plays an important role in cellular growth. This study was conducted to investigate a potential association of FGFR2 rs2981582 with breast cancer. DNA was obtained from 137 Formalin-fixed, paraffin-embedded tumors and 98 normal breast tissue samples. Genotypes were carried out with PCR-RFLP. The odds ratio and 95% confidence interval (CI) were used to evaluate the power of the associations. A significant association between FGFR2 rs2981582 C allele and susceptibility to breast cancer was found (p-value < 0.0001, Odds Ratio = 2.3, %95 CI (1.5–3.0). No significant differences in FGFR2 rs2981582 genotypes and alleles distribution among breast patients with different hormonal receptor status (p > 0.05) were detected. However, a significant difference was found in genotypes and alleles distribution in ER+, PR- and HER2 between breast cancer cases and controls. This study showed an association of FGFR2 rs2981582T/C with breast cancer in Saudi women, further large study is required to validate the results. 相似文献
226.
Andrea Engelbrecht Thomas Mörs Marcelo A. Reguero Jürgen Kriwet 《Historical Biology》2017,29(6):841-853
The highly fossiliferous Eocene deposits of the Antarctic Peninsula are among the most productive sites for fossil remains in the Southern Hemisphere and offer rare insights into high-latitude faunas during the Palaeogene. Chondrichthyans, which are represented by abundant isolated remains, seemingly dominate the marine assemblages. Eocene Antarctic sawsharks have only been known from few isolated rostral spines up to now, that were assigned to Pristiophorus lanceolatus. Here, we present the first oral teeth of a sawshark from the Eocene of Seymour Island and a re-evaluation of previously described Pristiophorus remains from Gondwana consisting exclusively of rostral spines. The holotype of Pristiophorus lanceolatus represents a single, abraded and insufficiently illustrated spine from the Oligocene of New Zealand. All other Cenozoic rostral spines assigned to this species are morphologically very indistinct and closely resemble those of living taxa. Consequently, we regard this species as dubious and introduce a new species, Pristiophorus laevis, based on oral teeth. The combination of dental characteristics of the new species makes it unique compared to all other described species based on oral teeth. Rostral spines from the Eocene of Seymour Island are assigned to this new species whereas those from other Cenozoic Gondwana localities remain ambiguous.
LSID urn:lsid:zoobank.org:pub:7177A373-527B-4315-85F6-25180DB5E087 相似文献
227.
Ahmed Mostafa Soliman Neveen Samy Gadallah Hathal Mohammed Al Dhafer 《Zoology in the Middle East.》2017,63(1):58-62
In the present study, the genus Gynecaptera Skorikov, 1935 is recorded from the Arabian Peninsula for the first time, with a nocturnal new species, G. arabica Soliman &; Gadallah, which has been collected from the Riyadh region in Saudi Arabia and which is described and illustrated.http://www.zoobank.org/urn:lsid:zoobank.org:pub:F7ACB779-3750-4DC6-B29B-B7F290E7C7B4 相似文献
228.
Glycine soja, also called wild soybean, is the wild ancestor of domesticated soybean (Glycine max), and one of the world's major cultivated crops. Wild soybean is a valuable resource for the breeding of cultivated soybean and harbors useful genes or agronomic traits. To use and conserve this valuable resource, we conducted a study to evaluate the genetic diversity and population structure of wild soybean using the sequencing data of two nuclear loci (AF105221 and PhyB) and one chloroplast locus (trnQ-rps16) of more than 600 individuals representing 53 populations throughout the natural distribution range. The results showed that most of the variation was found within the populations and groups, but significant genetic differentiation was also detected among different eco-geographical groups. Correlations between genetic and geographical distance at all the loci were consistent with the isolation by distance gene flow model. G. soja exhibited the highest genetic diversity in middle and downstream of Yangzi River (MDYR) region, followed by North East China (NEC), and was the lowest in North West China (NWC). We concluded that both in situ and ex situ conservation strategies required for wild soybean populations, especially which are native to MDYR and NEC regions. 相似文献
229.
Antonia Dawes 《Ethnic and racial studies》2017,40(1):114-132
This qualitative empirical study explores the articulation of meanings about difference, belonging and positionality that are emerging in English talk across transcultural boundaries in Naples, Southern Italy. It shows that the fraught encounters that take place on street markets, on public transport and at community events lead both to tactics of racialized closure, exclusion and division; as well as to the formation of innovative and ambivalent convivialities. In stressing the importance of talking English in intersubjective interactions it not only tells a story about the particular context and history of race relations in the city – where different sorts of speaking are central to a history of internal subordination and mass emigration – but also offers new ways of thinking about the complex and ambiguous multilingual reality that has resulted from intensified migration across the world. 相似文献
230.
ULRICH MEVE SAMIA HENEIDAK 《Botanical journal of the Linnean Society. Linnean Society of London》2005,149(4):419-432
The Apteranthes europaea complex (Apocynaceae–Asclepiadoideae–Ceropegieae–Stapeliinae) distributed from Morocco/southern Spain along the North African coast of the Mediterranean Sea up to Sinai, Negev and southern Jordan is studied with emphasis on stem and flower morphology by SEM, chromosome sizes and flavonoid compounds. Apteranthes europaea was found to be rich in rather uncommon flavone glycosides. Of these, luteolin 4'-neohesperidoside represents the major flavonoid of all samples; luteolin-3'- O -(6'- O -sinapoylglucoside)-4'- O -neohesperidoside and luteolin-3'- O -(6'- O -feruloylglucoside)-4'- O -neohesperidoside are reported here for the first time. Flavonol glycosides also occur, but in much smaller quantities. The different flower morphs, variation in stem and corolla epidermal structures, slight variations in the length of the 2 n = 22 chromosomes and in quantitative flavonoid composition are taxonomically best reflected by subdividing the complex into a western var. europaea (Europe and Africa) and an eastern var. judaica (Sinai, Arabia). © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 419–432. 相似文献