全文获取类型
收费全文 | 132篇 |
免费 | 9篇 |
出版年
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 7篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 15 毫秒
1.
Restriction endonucleases Cfo 1, Pvu II, Sma I, Hpa II, Taq I and Hae III were tested for their ability to induce SCEs in CHO cells. The results indicate that the DNA double-strand breaks induced during S-phase by these enzymes lead to an increase in the frequencies of SCEs. 相似文献
2.
A highly conserved nuclear gene for low-level phylogenetics: elongation factor-1 alpha recovers morphology-based tree for heliothine moths 总被引:8,自引:2,他引:6
Cho S; Mitchell A; Regier JC; Mitter C; Poole RW; Friedlander TP; Zhao S 《Molecular biology and evolution》1995,12(4):650-656
Molecular systematists need increased access to nuclear genes. Highly
conserved, low copy number protein-encoding nuclear genes have attractive
features for phylogenetic inference but have heretofore been applied mostly
to very ancient divergences. By virtue of their synonymous substitutions,
such genes should contain a wealth of information about lower-level
taxonomic relationships as well, with the advantage that amino acid
conservatism makes both alignment and primer definition straightforward. We
tested this postulate for the elongation factor-1 alpha (EF-1 alpha) gene
in the noctuid moth subfamily Heliothinae, which has probably diversified
since the middle Tertiary. We sequenced 1,240 bp in 18 taxa representing
heliothine groupings strongly supported by previous morphological and
allozyme studies. The single most parsimonious gene tree and the
neighbor-joining tree for all nucleotides show almost complete concordance
with the morphological tree. Homoplasy and pairwise divergence levels are
low, transition/transversion ratios are high, and phylogenetic information
is spread evenly across gene regions. The EF-1 alpha gene and presumably
other highly conserved genes hold much promise for phylogenetics of
Tertiary age eukaryote groups.
相似文献
3.
Cultured chick embryo fibroblasts derived from skin and skeletal muscle exhibit hyaluronidase activity both associated with the cell layer and secreted into the medium. Although both forms of the enzyme have a number of similar characteristics (R.W. Orkin and B.P. Toole, 1980, J. Biol. CHem. 255), they differ in thermal stability at neutral pH and in behavior on ion-exchange chromatography. Both forms of the enzyme are equally stable at acidic pH for long intervals, but the cell-associated hyaluronidase is significantly less stable than the secreted froms at neutral pH and at temperatures more than or equal to 30 degrees C. Neither the presence of proteases nor inhibitors of hyaluronidase appear to be involved in the cell-asspcoated enzyme. Chromatography of the two forms of hyaluronidase on carboxymethyl cellulose reveals that most (60-90 percent) of the secreted form of the enzyme elutes at a lower ionic strength than the cell- associated enzyme. Treatment of the secreted form of hyaluronidase with neuraminidase shifts its elution profile on carboxymethyl cellulose toward that of the cell-associated form, and also decreases its thermal stability at neutral pH. In contrast, treatment of the secreted form of hyaluronidase with alkaline phosphatase has no detectable effect. These data suggest that the secreted hyaluronidase differs from the cellular form in possessing additional sialic acid residues which endow the former with increased stability in the extracellular milieu. 相似文献
4.
Short treatment (up to 1 h) of cytosine arabinoside (araC) increases the frequencies of aberrations induced by X-rays in human lymphocytes, evaluated at the first mitosis following stimulation, or as prematurely condensed chromosomes of G0 nuclei. Parallel biochemical experiments using nucleoid sedimentation technique, demonstrate that araC inhibits rejoining of DNA-strand breaks effectively. These results point out that X-ray-induced short-lived DNA strand breaks lead to chromosomal aberrations in human lymphocytes. 相似文献
5.
van den Brink F. S. Meijers T. A. Hofma S. H. van Boven A. J. Nap A. Vonk A. Symersky P. Sjauw K. D. Knaapen P. 《Netherlands heart journal》2020,28(3):139-144
Netherlands Heart Journal - Complex high-risk percutaneous coronary intervention (PCI) is challenging and frequently accompanied by haemodynamic instability. Veno-arterial extracorporeal membrane... 相似文献
6.
W. C. Meijers T. Hoekstra T. Jaarsma D. J. van Veldhuisen R. A. de Boer 《Netherlands heart journal》2016,24(4):287-295
Aims
Heart failure with preserved ejection fraction (HFpEF) is common and its management remains difficult. B-type natriuretic peptide (BNP) levels are used to diagnose heart failure, and as an entry criterion for inclusion into trials. We investigated a population of HFpEF patients who had been randomised into a study based on clinical parameters, and compared those with low BNP levels to those with elevated BNP levels.Methods
We examined patients who had been enrolled in the Coordinating study evaluating Outcomes of Advising and Counselling in Heart Failure (COACH), with preserved left ventricular ejection fraction (LVEF ≥ 40 %), and compared those with low BNP (< 100 pg/ml; n = 30) to those with elevated BNP (≥ 100 pg/ml; n = 127). Baseline characteristics, comorbidities, biomarkers, quality of life, and outcome parameters (hospitalisations and death) were compared between the groups. To validate our findings, we repeated all analyses for NT-proBNP (< 300 pg/ml and ≥ 300 pg/ml).Results
Patients were similar with regard to most clinical characteristics (including age, sex, and LVEF), biomarkers, and comorbidities. In contrast, patients with a low BNP had higher body mass index levels (31 kg/m2 vs. 27 kg/m2; p < 0.01) and lower cardiac troponin I (9 pg/ml vs. 15 pg/ml; p = 0.02). In addition, these patients were less frequently prescribed diuretics and beta-blockers. No differences in quality of life, heart failure related symptoms and the primary and secondary outcomes were observed between these groups. These observations were confirmed for NT-proBNP.Conclusion
Among the patients with clinically diagnosed HFpEF, those with low BNP are strikingly similar to those with elevated BNP levels, except for BMI, which was significantly higher in these patients.Electronic supplementary material
The online version of this article (doi:10.1007/s12471-016-0816-8) contains supplementary material, which is available to authorized users. 相似文献7.
A PBX1 transcriptional network controls dopaminergic neuron development and is impaired in Parkinson's disease 下载免费PDF全文
J Carlos Villaescusa Bingsi Li Enrique M Toledo Pia Rivetti di Val Cervo Shanzheng Yang Simon RW Stott Karol Kaiser Saiful Islam Daniel Gyllborg Rocio Laguna‐Goya Michael Landreh Peter Lönnerberg Anna Falk Tomas Bergman Roger A Barker Sten Linnarsson Licia Selleri Ernest Arenas 《The EMBO journal》2016,35(18):1963-1978
8.
9.
Marx PF Hackeng TM Dawson PE Griffin JH Meijers JC Bouma BN 《The Journal of biological chemistry》2000,275(17):12410-12415
Thrombin-activable fibrinolysis inhibitor (TAFI) is present in the circulation as an inactive zymogen. Thrombin converts TAFI to a carboxypeptidase B-like enzyme (TAFIa) by cleaving at Arg(92) in a process accelerated by the cofactor, thrombomodulin. TAFIa attenuates fibrinolysis. TAFIa can be inactivated by both proteolysis by thrombin and spontaneous temperature-dependent loss of activity. The identity of the thrombin cleavage site responsible for loss of TAFIa activity was suggested to be Arg(330), but site-directed mutagenesis of this residue did not prevent inactivation of TAFIa by thrombin. In this study we followed TAFI activation and TAFIa inactivation by thrombin/thrombomodulin in time and characterized the cleavage pattern of TAFI using matrix-assisted laser desorption ionization mass spectrometry. Mass matching of the fragments revealed that TAFIa was cleaved at Arg(302). Studies of a mutant R302Q-TAFI confirmed identification of this thrombin cleavage site and, furthermore, suggested that inactivation of TAFIa is based on its conformational instability rather than proteolytic cleavage at Arg(302). 相似文献
10.
Ling?HuangEmail author Anton?W.?Langerak Ingrid?L.?M.?Wolvers-Tettero Ruud?W.?J.?Meijers Carla?C.?Baan Nicolle?H.?R.?Litjens Michiel?G.?H.?Betjes 《Immunity & ageing : I & A》2015,12(1):28