全文获取类型
收费全文 | 2623篇 |
免费 | 90篇 |
国内免费 | 4篇 |
出版年
2021年 | 26篇 |
2018年 | 57篇 |
2017年 | 39篇 |
2016年 | 48篇 |
2015年 | 69篇 |
2014年 | 59篇 |
2013年 | 127篇 |
2012年 | 103篇 |
2011年 | 112篇 |
2010年 | 82篇 |
2009年 | 68篇 |
2008年 | 79篇 |
2007年 | 99篇 |
2006年 | 74篇 |
2005年 | 95篇 |
2004年 | 84篇 |
2003年 | 73篇 |
2002年 | 82篇 |
2001年 | 47篇 |
2000年 | 52篇 |
1999年 | 39篇 |
1998年 | 27篇 |
1997年 | 27篇 |
1996年 | 27篇 |
1995年 | 22篇 |
1994年 | 32篇 |
1993年 | 28篇 |
1992年 | 39篇 |
1991年 | 47篇 |
1990年 | 36篇 |
1989年 | 36篇 |
1988年 | 52篇 |
1987年 | 43篇 |
1986年 | 53篇 |
1985年 | 44篇 |
1984年 | 40篇 |
1983年 | 30篇 |
1982年 | 27篇 |
1981年 | 31篇 |
1979年 | 32篇 |
1978年 | 34篇 |
1977年 | 37篇 |
1976年 | 32篇 |
1975年 | 34篇 |
1974年 | 31篇 |
1973年 | 28篇 |
1972年 | 30篇 |
1971年 | 26篇 |
1970年 | 21篇 |
1969年 | 22篇 |
排序方式: 共有2717条查询结果,搜索用时 250 毫秒
51.
52.
53.
54.
Hansel Gómez Mae Chappé Pedro A Valiente Tirso Pons María de Los Angeles Chávez Jean-Louis Charli Isel Pascual 《Journal of biosciences》2013,38(3):461-469
Dipeptidyl peptidase IV (DPP-IV) is an ectopeptidase with many roles, and a target of therapies for different pathologies. Zinc and calcium produce mixed inhibition of porcine DPP-IV activity. To investigate whether these results may be generalized to mammalian DPP-IV orthologues, we purified the intact membrane-bound form from rat kidney. Rat DPP-IV hydrolysed Gly-Pro-p-nitroanilide with an average Vmax of 0.86±0.01 μmol min–1mL–1 and KM of 76±6 μM. The enzyme was inhibited by the DPP-IV family inhibitor l-threo-Ile-thiazolidide (Ki=64.0±0.53 nM), competitively inhibited by bacitracin (Ki=0.16±0.01 mM) and bestatin (Ki=0.23±0.02 mM), and irreversibly inhibited by TLCK (IC50 value of 1.20±0.11 mM). The enzyme was also inhibited by divalent ions like Zn2+ and Ca2+, for which a mixed inhibition mechanism was observed (Ki values of the competitive component: 0.15±0.01 mM and 50.0±1.05 mM, respectively). According to bioinformatic tools, Ca2+ ions preferentially bound to the β-propeller domain of the rat and human enzymes, while Zn2+ ions to the α-β hydrolase domain; the binding sites were essentially the same that were previously reported for the porcine DPP-IV. These data suggest that the cationic susceptibility of mammalian DPP-IV orthologues involves conserved mechanisms. 相似文献
55.
Jaqueline Raymondi Silva Larissa Campos de Medeiros Vinícius Pinho dos Reis Juliana Helena Chávez Thiago Demarchi Munhoz Gustavo Puia Borges Otavio Augusto Brioschi Soares Carlos Henrique Coelho de Campos Rosangela Zacarias Machado Cristiane Divan Baldani Maria Luana Cristiny Rodrigues Silva Joice Lara Maia Faria Edson Elias da Silva Luiz Tadeu Moraes Figueiredo 《Memórias do Instituto Oswaldo Cruz》2013,108(7):921-923
Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country. 相似文献
56.
Hisaaki Yamamoto Chōjirō Tomizawa Yasuhiko Uesugi Toshinobu Murai 《Bioscience, biotechnology, and biochemistry》2013,77(7):1553-1561
Behavior and metabolism of O,O-diisopropyl S-benzyl phosphorothiolate (Kitazin P©) in rice plant were examined using 32P, 35S-double labeled compound. Uptake of Kitazin P by the plant was different with the growth stages of the plant, and the rate of uptake was rapid in early growth stage. Kitazin P penetrated into plant tissues was gradually hydrolyzed to produce O,O-diisopropyl hydrogen phosphorothioate which was converted to diisopropyl hydrogen phosphate, isopropyl dihydrogen phosphate and phosphoric acid. As toluene soluble metabolites, eight spots were detected by thin-layer chromatography, but their percentages in toluene soluble fraction were extremely low as compared with that of Kitazin P. Only two metabolites, dibenzyl disulfide and O,O-diisopropyl O-benzyl phosphorothionate were identified by a gas-liquid chromatography with a flame thermionic detector or a flame photometric detector. Diisopropyl hydrogen phosphorothioate was detected as a persistent metabolite even in rice grains. 相似文献
57.
58.
Usha R. Dutta Vijaya Kumar Pidugu Ch. Venkateshwar Goud Christiane Hoefers Monika Hagemann Ashwin Dalal 《Gene》2013
Ambiguous genitalia or disorder of the sexual development is a birth defect where the external genitals do not have the typical appearance of either a male or female. Here we report a boy with ambiguous genitalia and short stature. The cytogenetic analysis by G-banding revealed a small Y chromosome and an additional material on the 15p arm. Further, molecular cytogenetic analysis by Fluorescence in situ hybridization (FISH) using whole chromosome paint probes showed the presence of Y sequences on the 15p arm, confirming that it is a Y;15 translocation. Subsequent, FISH with centromere probe Y showed two signals depicting the presence of two centromeres and differing with a balanced translocation. The dicentric nature of the derivative 15 chromosome was confirmed by FISH with both 15 and Y centromeric probes. Further, the delineation of the Y chromosomal DNA was also done by quantitative real time PCR. Additional Y-short tandem repeat typing was performed to find out the extent of deletion on small Y chromosome. Fine mapping was carried out with 8 Y specific BAC clones which helped in defining the breakpoint regions. MLPA was performed to check the presence or absence of subtelomeric regions and SHOX regions on Y. Finally array CGH helped us in confirming the breakpoint regions. In our study we identified and characterized a novel complex Y chromosomal rearrangement with a complete deletion of the Yq region and duplication of the Yp region with one copy being translocated onto the15p arm. This is the first report of novel and unique Y complex rearrangement showing a deletion, duplication and a translocation in the same patient. The possible mechanism of the rearrangement and the phenotype–genotype correlation are discussed. 相似文献
59.
Livestock wastewater that is discharged into rivers and ponds results in eutrophication, which would then cause an increase in microorganisms, microalgae, and macrophytes. The derivatives of which critically damage aquatic life and agricultural irrigation. This study designed a swine farm wastewater bioremediation system, by using tubular chained cyanobacteria-immobilized agar–alginate blocks and cyanobacteria biological absorption to reduce wastewater pollution. Swine farm wastewater was filtered through a long tube stuffed with cyanobacteria (Dermocarpella sp.)-immobilized agar–alginate blocks. The removal efficiencies of biological oxygen demand, chemical oxygen demand, phosphorous, ammonia, and suspension solids were evaluated. 相似文献
60.
Susmitha Valli Gogula Ch Divakar Ch Satyanarayana Yedla Phani Kumar Vadapalli Santhosi Lavanaya 《Bioinformation》2013,9(20):1040-1043
Diabetic Retinopathy (DR) is one of the attenuating complications of diabetes mellitus. The key gene responsible for causing
diabetic retinopathy is protein kinase C beta (PKCβ). Protein kinase C is a family of protein kinase enzymes which are involved in
controlling the function of other proteins through phosphorylation mechanism and plays a crucial role in signal transduction
mechanisms. Among all the PKC isoenzymes, PKCβ could be a significant isoenzyme involved in vascular dysfunction during
hyperglycemia. Studies show that oral administration of PKCβ inhibitor Ruboxistaurin (), decreases vessel permeability
and improves retinal condition. Thus compounds that decrease the PKCβ activation would be helpful in the treatment of diabetic
retinopathy. The compounds similar to Ruboxistaurin are taken from Super Target database and docking analysis was performed.
Maleimide derivative 3 showed highest binding affinities compared to Ruboxistaurin and so we advise that compound may be
utilized in the treatment of diabetic retinopathy. LY333531相似文献