全文获取类型
收费全文 | 5699篇 |
免费 | 440篇 |
专业分类
6139篇 |
出版年
2023年 | 37篇 |
2022年 | 83篇 |
2021年 | 151篇 |
2020年 | 69篇 |
2019年 | 120篇 |
2018年 | 138篇 |
2017年 | 131篇 |
2016年 | 201篇 |
2015年 | 311篇 |
2014年 | 345篇 |
2013年 | 442篇 |
2012年 | 521篇 |
2011年 | 508篇 |
2010年 | 319篇 |
2009年 | 258篇 |
2008年 | 342篇 |
2007年 | 346篇 |
2006年 | 314篇 |
2005年 | 257篇 |
2004年 | 251篇 |
2003年 | 224篇 |
2002年 | 200篇 |
2001年 | 45篇 |
2000年 | 37篇 |
1999年 | 51篇 |
1998年 | 51篇 |
1997年 | 23篇 |
1996年 | 26篇 |
1995年 | 25篇 |
1994年 | 18篇 |
1993年 | 22篇 |
1992年 | 36篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 13篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1970年 | 4篇 |
1969年 | 4篇 |
1897年 | 4篇 |
排序方式: 共有6139条查询结果,搜索用时 15 毫秒
91.
Arendt Y Banci L Bertini I Cantini F Cozzi R Del Conte R Gonnelli L 《FEBS letters》2007,581(24):4723-4726
The solution structure of the catalytic domain of MMP-20, a member of the matrix metalloproteinases family not yet structurally characterized, complexed with N-Isobutyl-N-(4-methoxyphenylsulfonyl)glycyl hydroxamic acid (NNGH), is here reported and compared with other MMPs-NNGH adducts. The backbone dynamic has been characterized as well. We have found that, despite the same fold and very high overall similarity, the present structure experiences specific structural and dynamical similarities with some MMPs and differences with others, around the catalytic cavity. The present solution structure, not only contributes to fill the gap of structural knowledge on human MMPs, but also provides further information to design more selective and efficient inhibitors for a specific member of this class of proteins. 相似文献
92.
Banci L Bertini I Cantini F Della-Malva N Migliardi M Rosato A 《The Journal of biological chemistry》2007,282(32):23140-23146
ATP7A is a P-type ATPase involved in copper(I) homeostasis in humans. It possesses a long N-terminal cytosolic tail containing six domains that are individually folded and capable of binding one copper(I) ion each. We investigated the entire N-terminal tail (MNK1-6) in solution by NMR spectroscopy and addressed its interaction with copper(I) and with copper(I)-HAH1, the physiological partner of ATP7A. At copper(I)-HAH1:MNK1-6 ratios of up to 3:1, thus encompassing the range of protein ratios in vivo, both the first and fourth domain of the tail formed a metal-mediated adduct with HAH1 whereas the sixth domain was simultaneously able to partly remove copper(I) from HAH1. These processes are not dependent on one another. In particular, formation of the adducts is not necessary for copper(I) transfer from HAH1 to the sixth domain. The present data, together with available in vivo studies, suggest that the localization of ATP7A between the trans-Golgi network and the plasma membrane may be regulated by the accumulation of the adducts with HAH1, whereas the main role of domains 5 and 6 is to assist copper(I) translocation. 相似文献
93.
Malolactic fermentation is a process that is influenced by various factors that can inhibit the growth of the malolactic bacteria. Inhibitory metabolites produced by yeast may have an important role in the correct development of malolactic fermentation. For these reasons, we have investigated the effects of such metabolites on the growth of malolactic bacteria under different environmental conditions, to aid in our understanding of the significance of these interactions in the wine-making environment. Our screening methods to detect interactions between yeast and malolactic bacteria showed a variable and wide diffusion of yeast inhibitory activity on the growth of the malolactic bacteria. However, this first approach to determine this inhibitory activity of yeast gave an overestimation when compared to the results obtained under actual wine-making conditions. The evaluation of malic acid consumption indicated that under inhibitory conditions a partial L-malic acid degradation was seen, indicating that the malolactic activity continued without bacterial growth. However, these yeast-inhibiting effects in addition to other environmental factors could cause a complete failure of malolactic fermentation. 相似文献
94.
95.
Sphingolipids are major constituents of biological membrane and some of them behave as second messengers involved in the cell fate decision. Ceramide and sphingosine 1-phosphate (S1P) constitute a rheostat system in which ceramide promotes cell death and S1P increases cell survival. We have shown that both sphingolipids are able to trigger autophagy with opposing outcomes on cell survival. Here we discuss and speculate on the diverging functions of the autophagic pathways induced by ceramide and S1P, respectively. 相似文献
96.
97.
98.
Chiara Salvesi Stefania Silvi Dennis Fiorini Serena Scortichini Gianni Sagratini Francesco A. Palermo Renato De Leone Nadaniela Egidi Lorella Fatone Carlo Cifani Amedeo Amedei Francesca Scocchera Mara Morici Beatrice Gatto Fausto Mannucci Valerio Valeriani Marco Malavasi Sara Servili Andrea Casula Andrea Cresci Ivano Corradetti Francesco Carpi Matteo Picciolini Maria Magdalena Coman Maria Cristina Verdenelli 《Journal of applied microbiology》2022,133(5):2941-2953
99.
100.
Marco Savioli Lorenzo Antonelli Gianfranco Bocchinfuso Francesca Cavalieri Rita Cimino Emanuela Gatto Ernesto Placidi Julio Raul Fernandez Masso Hilda Garay Perez Hector Santana Maribel Guerra-Vallespi Mariano Venanzi 《Journal of peptide science》2022,28(1):e3356
Synthetic therapeutic peptides (STP) are intensively studied as new-generation drugs, characterized by high purity, biocompatibility, selectivity and stereochemical control. However, most of the studies are focussed on the bioactivity of STP without considering how the formulation actually used for therapy administration could alter the physico-chemical properties of the active principle. The aggregation properties of a 20-mer STP (Ac-His-Ala-Arg-Ile-Lys-D-Pro-Thr-Phe-Arg-Arg-D-Leu-Lys-Trp-Lys-Tyr-Lys-Gly-Lys-Phe-Trp-NH2), showing antitumor activity, were investigated by optical spectroscopy and atomic force microscopy imaging, as itself (CIGB552) and in its therapeutic formulation (CIGB552TF). It has found that the therapeutic formulation deeply affects the aggregation properties of the investigated peptide and the morphology of the aggregates formed on mica by deposition of CIGB552 and CIGB552TF millimolar solutions. Molecular dynamics simulations studied the first steps of CIGB552 aggregation under physiological ionic strength conditions (NaCl 150 mM), showing that peptide oligomers, from dimers to tetramers, are preferentially formed in this environment. Interestingly, cell viability assays performed on H-460 cell lines indicate a major antiproliferative activity of the peptide in its therapeutic formulation with respect to the peptide aqueous solution. 相似文献