全文获取类型
收费全文 | 262篇 |
免费 | 33篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 23篇 |
2015年 | 8篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 24篇 |
2011年 | 24篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 3篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
排序方式: 共有295条查询结果,搜索用时 276 毫秒
251.
Mohamed Seddik Mahmoud Bougi Syrine Baklouti M. A. Rasheed P. L. Srinivasa Rao Syed Zaheer Hasan Jawhar Gharbi 《Geomicrobiology journal》2019,36(4):348-358
Microbial prospecting technique was applied in El Hajeb oilfield, Tunisia for potential hydrocarbon resource exploration by examining the anomalous abundance of hydrocarbon oxidizing bacteria. The method depends on the seepage of light gaseous hydrocarbons such as C1 – C5 from the petroleum pools to the shallow surface giving the reasonable conditions to the development of highly specialized bacterial population. A total of 51 soil samples were collected from 1.5 m depth. Bacterial counts for n-propane utilizing bacteria ranged between nil and 2.44?×?105?cfu/gm. The light gaseous hydrocarbons analysis showed that their concentrations were 102, 55, 41, 20, 21, 19, 10 and 141 ppb for C1, C2, C3, iC4, nC4, iC5, nC5 and ΣC2+, respectively. The gas concentration maps showed the presence of dynamic hydrocarbons micro-seepage from petroleum systems. The integrated geomicrobial and adsorbed soil gas results demonstrated that the anomalous hydrocarbon zones spread in all territory which could presumably help to evaluate highpotentialareas. In conclusion, our study confirms that the use of microbial data and adsorbed gas analyses of soil samples is a low cost tool for hydrocarbon exploration. This technique has been confirmed and can be applied successfully in frontier basins. 相似文献
252.
Yangyang Pan Meng Wang Abdul Rasheed Baloch Qiang Zhang Jinglei Wang Rui Ma Gengquan Xu Jam Kashif Libin Wang Jiangfeng Fan Yan Cui Sijiu Yu 《Journal of cellular physiology》2019,234(10):17677-17689
The fusion of sperm and oocytes determines the fertilization competence and subsequent development of embryos, which, in turn, can be affected by various proteins and DNA methylation. However, several factors in this whole regulation process remain unknown, especially in yaks. Here, we report that fibroblast growth factor 10 (FGF10) is an important growth factor that can enhance the maturation rate of yak oocytes and the motility of frozen spermatozoa. Subsequent blastocyst quality was also improved by increasing the total cell number and level of pregnancy-associated protein in blastocysts. These effects were significantly high in the group that received the 5 ng/ml FGF10 treatment, during both in vitro maturation (IVM) and capacitation. Our data show that the effects of FGF10 were dose-dependent at vital steps of embryogenesis in vitro. Furthermore, quantitative polymerase chain reaction, western blot analysis, and immunofluorescence demonstrated that the levels of CD9, CD81, DNMT1, and DNMT3B in both mature cumulus-oocyte complexes and capacitated sperms were regulated by FGF10, which was also highly expressed in the group treated with 5 ng/ml FGF10 during both IVM and capacitation. From our present study, we concluded that FGF10 promotes yak oocyte fertilization competence and subsequent blastocyst quality, and could also regulate CD9, CD81, DNMT1, and DNMT3B to optimize sperm–oocyte interactions and DNA methylation during fertilization. 相似文献
253.
IL-15 plays a seminal role in innate immunity through enhancing the cytotoxic function as well as cytokine production by NK and T cells. We have previously shown that exposure of PBMC as well as monocytic cells to different viruses results in immediate up-regulation of IL-15 gene expression and subsequent NK cell activation as an innate immune response of those cells to these viruses. However, no signaling pathway involved in this up-regulation has been identified. Here we show for the first time that HSV-1-induced up-regulation of IL-15 gene expression is independent of viral infectivity/replication. IL-15 gene is up-regulated by HSV-1 in human monocytes, but not in CD3+ T cells. HSV-1 induces the phosphorylation of protein tyrosine kinases (PTKs) and protein kinase C (PKC) for inducing IL-15 expression in monocytic cells. Inhibitors for PTKs reduced HSV-1-induced PTK activity, DNA binding activity of NF-kB as well as IL-15 gene expression. In contrast, an inhibitor for membrane-bound tyrosine kinases had no effect on these events. Experiments using PKC inhibitors revealed that phosphorylation of PKC zeta/lambda (PKC zeta/lambda), DNA binding activity of NF-kB and HSV-1-induced up-regulation of IL-15 were all decreased. Furthermore, we found that HSV-1-induced IL-15 up-regulation was also dependent on PTKs regulation of PKC phosphorylation. Thus, we conclude that IL-15 up-regulation in HSV-1-treated monocytic cells is dependent on the activity of both PTKs and PKC zeta/lambda. 相似文献
254.
Ahmed Mushtaq Mushtaq Nadia Sher Naila Morel Ademir F. 《International journal of peptide research and therapeutics》2022,28(6):1-8
International Journal of Peptide Research and Therapeutics - In the current study, the cyclopeptide alkaloid discarine D-derived tri-peptides fragments were synthesized and then investigated for... 相似文献
255.
256.
257.
Cladistic analysis of self‐grooming indicates a single origin of eusociality in corbiculate bees (Hymenoptera: Apidae) 下载免费PDF全文
Naila Cristina de Souza Canevazzi Fernando Barbosa Noll 《Cladistics : the international journal of the Willi Hennig Society》2015,31(2):126-141
Behavioural traits have been used extensively in recent years as an important character source for making phylogenetic inferences. The phylogenetic positions of the members of the Apini subtribe are increasingly being debated, and new characters must be examined. We analysed the presence and absence of certain behavioural patterns, as well as the sequences of some of these patterns, to generate 79 characters. Eleven species comprised the ingroup, and Xylocopini comprised the outgroup. Parsimony analysis showed that the most parsimonious tree was (Euglossina(Bombina(Apina+Meliponina))). This topology is consistent with most studies that use morphological data and the few that use behavioural data, which suggests that advanced eusociality arose only once in a common ancestor of the clade Apina plus Meliponina; however, this hypothesis is inconsistent with our molecular data. Thus we considered behavioural, molecular, and morphological data and recovered the same topology, in which eusociality has a single origin in corbiculate bees. 相似文献
258.
259.
Molecular cloning, genomic analysis, and biological properties of rat leukemia virus and the onc sequences of Rasheed rat sarcoma virus. 下载免费PDF全文
M A Gonda H A Young J E Elser S Rasheed C B Talmadge K Nagashima C C Li R V Gilden 《Journal of virology》1982,44(2):520-529
Rasheed rat sarcoma virus (RaSV) has been shown to code for a protein of 29,000 Mr not present in replication-competent rat type C helper virus (RaLV)-infected cells. This protein is a fused gene product consisting of a portion of the RaLV p15 gag protein and the transformation-specific 21,000 Mr (p21) ras protein, which is also found in Harvey murine sarcoma virus. We now report the molecular cloning of both the SD-1 (Sprague-Dawley) strain of RaLV and the transforming ras sequences of RaSV. Heteroduplex analysis of these cloned DNAs demonstrated that the RaSV ras gene (v-Ra-ras) was inserted into the rat type C viral genome with a small deletion of RaLV genetic information in the 5' region of the gag gene and that the v-Ra-ras gene (0.72 kilobase pair) is homologous to and colinear with the p21 ras gene of Harvey murine sarcoma virus (v-Ha-ras). Restriction enzyme mapping confirmed the homology demonstrated by heteroduplex mapping, showing strong site conservation of restriction endonucleases known to cleave v-Ha-ras. Cloned v-Ra-ras DNA transformed NIH 3T3 cells, inducing the synthesis of the p29 RaSVgag-ras protein. 相似文献
260.
Treatment of the roots of 24–48 h old seedlings of the forage legumeLotus corniculatus with 1.0% Cellulase YC, and 0.1% Pectolyase Y-23 in 4.2% mannitol solution released protoplasts from the tips of root hairs within 30–40 sec of enzyme incubation. Roots from approximately 1000 seedlings yielded 1.7×105 protoplasts. Ten percent of protoplasts divided to form cell colonies when cultured at 1.0×105 ml–1 in droplets of KM8P medium with 0.6% Sea Plaque agarose. Colonies formed callus on UM agar medium; protoplast-derived tissues produced shoots on B5 medium containing 0.05 mg 1–1 of BAP. Regenerated plants were phenotypically and cytologically normal (2n=2x=24±2), and produced nitrogen fixing root nodules following inoculation withRhizobium. These results confirm the totipotency of protoplasts isolated from specialised epidermal cells of seedling roots ofLotus corniculatus. 相似文献