全文获取类型
收费全文 | 564篇 |
免费 | 25篇 |
出版年
2023年 | 2篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 12篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 23篇 |
2013年 | 32篇 |
2012年 | 36篇 |
2011年 | 46篇 |
2010年 | 19篇 |
2009年 | 21篇 |
2008年 | 46篇 |
2007年 | 37篇 |
2006年 | 29篇 |
2005年 | 34篇 |
2004年 | 29篇 |
2003年 | 24篇 |
2002年 | 25篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1994年 | 4篇 |
1992年 | 3篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1988年 | 7篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1969年 | 2篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1965年 | 3篇 |
1964年 | 1篇 |
排序方式: 共有589条查询结果,搜索用时 31 毫秒
101.
Kayo Ikeda Koji Suzuki Hideki Yoshioka Katsushiro Miyamoto Tsutomu Masujima Masanori Sugiyama 《FEMS microbiology letters》1998,168(2):195-199
Streptomyces castaneoglobisporus HUT6202 overproduces a diffusible melanin pigment and harbors a cryptic 7.4-kb plasmid, pHY6202. We constructed a Streptomyces cloning vector, pSY10CMM, consisting of the HUT6202 rep gene, the thiostrepton resistance gene and an operon encoding the synthesis of melanin pigment, abbreviated mel, from S. castaneoglobisporus. The vector, which has SphI and BamHI sites as cloning sites with insertional inactivation of the mel, is a more convenient cloning vector than commonly used pIJ702, because of its broad host range for antibiotic-producing Streptomyces strains and its much greater production of diffusible melanin pigment. 相似文献
102.
Polycomb group genes were originally identified in Drosophila as repressors required to maintain the silenced state of homeotic loci. About ten Polycomb group genes have been cloned in Drosophila, and mammalian homologs have been identified for most of these. Here, we isolate cDNAs encoding two isoforms of a human homolog of Drosophila Sex comb on midleg (Scm), named Sex comb on midleg homolog-1 (SCMH1). Overall, SCMH1 has 94% identity to its mouse counterpart Scmh1, and 41% identity to Scm, and contains two 1(3)mbt domains, and the SPM domain that are characteristic of Scm. SCMH1 is widely expressed in adult tissues, and maps to chromosome 1p34. 相似文献
103.
104.
Goto M Ueda K Hashimoto T Fujiwara S Matsuyama K Kometani T Kanazawa K 《Free radical biology & medicine》2008,45(9):1318-1325
The oxidative formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in DNA is closely associated with the induction of degenerative diseases, including cancer. However, the oxidant species participating in the formation of 8-OHdG has yet to be fully clarified. On the basis that peroxyl radicals are a strong candidate for this species, we employed 2,2'-azobis(2-amidinopropane) (AAPH) as a peroxyl radical generator. Exposure of calf thymus DNA to AAPH formed 8-OHdG, but the exposure of 2'-deoxyguanosine (dG) alone did not. From the exposure of various combinations of nucleotides, 8-OHdG was formed only in the presence of dG and thymidine (dT). A mix of dG with an oxidation product of dT, 5-(hydroperoxymethyl)-2'-deoxyuridine, produced 8-OHdG, but the amount formed was small. In contrast, 8-OHdG was produced abundantly by the addition of dG to peroxidized dT with AAPH. Thus, the formation of 8-OHdG was mediated by the peroxidized dT. Instead of artificial AAPH, endogenous peroxyl radicals are known to be lipid peroxides, which are probably the oxidant species for 8-OHdG formation mediated by thymidine in vivo. 相似文献
105.
Modelling and predicting the potential habitat and future range expansion of invasive species can help managers to mitigate
the impact of such species. Because habitat suitability and the colonization process are key determinants of range expansion,
inferences drawn from invasion patterns should be based on both attributes. To predict the potential habitat and expansion
rate of the invasive tree Bischofia javanica on Hahajima Island, we used simultaneous models of habitat and dispersal to estimate the effect of environment and dispersal
from the source population on the current distribution. We compared the fit and the estimated magnitudes of the environment
and dispersal effects in the simultaneous models with those in habitat suitability and colonization kernel models. The values
of Akaike’s information criterion for the simultaneous models were better than those of the habitat suitability and colonization
kernel models, indicating that the current distribution of Bischofia was determined by both environment and dispersal. The simultaneous models predicted that the potential habitat of Bischofia would be larger than that predicted by the habitat suitability model. The potential habitat distribution and future invasion
predicted by the simultaneous models will contribute to the development of specific landscape-scale management plans to control
this invasive species. 相似文献
106.
Ken-ichi Morishita Nobumasa Yakushiji Fuminori Ohsawa Kayo Takamatsu Nobuyasu Matsuura Makoto Makishima Masatoshi Kawahata Kentaro Yamaguchi Akihiro Tai Kenji Sasaki Hiroki Kakuta 《Bioorganic & medicinal chemistry letters》2009,19(3):1001-1003
Retinoid X receptor (RXR) ligands are attractive candidates for clinical application because of their activity against tamoxifen-resistant breast cancer, taxol-resistant lung cancer, metabolic syndrome, and allergy. Though several RXR ligands, especially RXR antagonists, have been reported, the rational molecular design of such compounds is not well advanced. 4-[N-Methanesulfonyl-N-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)amino]nicotinic acid (5a) is a moderately RXRα-preferential agonist, and we examined the feasibility of replacing the methyl group on the sulfonamide with a longer alkyl chain or an aromatic ring as an approach to produce new RXR antagonists. Several of the resulting benzenesulfonanilide-type compounds showed RXR antagonist activity. This design strategy should be a useful approach for addressing the lack of structure diversity of RXR antagonists. 相似文献
107.
108.
109.
Sumi D Fukushima K Miyataka H Himeno S 《Biochemical and biophysical research communications》2011,(1):48-53
Arsenic (+3 oxidation state) methyltransferase (As3MT) catalyzes the methylation of trivalent arsenic (As(III)) to monomethylarsonate (MMA(V)) and dimethylarsinic acid (DMA(V)), and plays an important role in the detoxification of arsenicals. Here, we report the identification of two splicing variants of the human As3MT gene. One splicing variant was an exon-3 skipping (Δ3) form which produced a premature stop codon, and the other was an exon-4 and -5 skipping (Δ4,5) form which produced a 31.1 kDa As3MT protein. In addition to the full-length mRNA of As3MT, Δ4,5 mRNAs were detected in HepG2, A549, HL60, K562, and HEK293 cells. The methyltransferase activity of the recombinant Δ4,5 As3MT and wild-type As3MT proteins purified from Escherichia coli was determined. Speciation analysis by HPLC–ICP-MS showed a clear peak of MMA(V) after incubation of As(III) with the wild-type As3MT protein, but not with the Δ4,5 As3MT protein. In addition, COS-7 cells transfected with Δ4,5 As3MT cDNA did not convert As(III) to MMA(V) or DMA(V). The lack of methyltransferase activity of Δ4,5 As3MT seems to be related to the deletion of an S-adenosylmethionine-binding site and a critical cysteine residue. These data suggest that the expression pattern of splicing variants of the As3MT gene may affect the capacity for arsenic methylation in cells. 相似文献