全文获取类型
收费全文 | 4770篇 |
免费 | 327篇 |
国内免费 | 5篇 |
专业分类
5102篇 |
出版年
2024年 | 3篇 |
2023年 | 40篇 |
2022年 | 80篇 |
2021年 | 156篇 |
2020年 | 87篇 |
2019年 | 114篇 |
2018年 | 167篇 |
2017年 | 117篇 |
2016年 | 187篇 |
2015年 | 270篇 |
2014年 | 285篇 |
2013年 | 349篇 |
2012年 | 437篇 |
2011年 | 467篇 |
2010年 | 286篇 |
2009年 | 229篇 |
2008年 | 262篇 |
2007年 | 331篇 |
2006年 | 253篇 |
2005年 | 231篇 |
2004年 | 220篇 |
2003年 | 186篇 |
2002年 | 152篇 |
2001年 | 34篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 28篇 |
1997年 | 18篇 |
1996年 | 18篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有5102条查询结果,搜索用时 15 毫秒
101.
Ailec Ho‐Plagaro Concepcin Santiago‐Fernandez Cristina Rodríguez‐Díaz Carlos Lopez‐Gmez Sara Garcia‐Serrano Francisca Rodríguez‐Pacheco Sergio Valdes Alberto Rodríguez‐Caete Guillermo Alcaín‐Martínez Natalia Ruiz‐Santana Luis Vzquez‐Pedreo Eduardo García‐Fuentes 《Obesity (Silver Spring, Md.)》2020,28(9):1708-1717
102.
Morán-Barrio J González JM Lisa MN Costello AL Peraro MD Carloni P Bennett B Tierney DL Limansky AS Viale AM Vila AJ 《The Journal of biological chemistry》2007,282(25):18286-18293
Metallo-beta-lactamases (MbetaLs) are zinc-dependent enzymes able to hydrolyze and inactivate most beta-lactam antibiotics. The large diversity of active site structures and metal content among MbetaLs from different sources has limited the design of a pan-MbetaL inhibitor. Here we report the biochemical and biophysical characterization of a novel MbetaL, GOB-18, from a clinical isolate of a Gram-negative opportunistic pathogen, Elizabethkingia meningoseptica. Different spectroscopic techniques, three-dimensional modeling, and mutagenesis experiments, reveal that the Zn(II) ion is bound to Asp120, His121, His263, and a solvent molecule, i.e. in the canonical Zn2 site of dinuclear MbetaLs. Contrasting all other related MbetaLs, GOB-18 is fully active against a broad range of beta-lactam substrates using a single Zn(II) ion in this site. These data further enlarge the structural diversity of MbetaLs. 相似文献
103.
Three types of DNA: approximately 2700 bp polydeoxyguanylic olydeoxycytidylic acid [poly(dG)-poly(dC)], approximately 2700 bp polydeoxyadenylic polydeoxythymidylic acid [poly(dA)-poly(dT)] and 2686 bp linear plasmid pUC19 were deposited on a mica surface and imaged by atomic force microscopy. Contour length measurements show that the average length of poly(dG)-poly(dC) is approximately 30% shorter than that of poly(dA)-poly(dT) and the plasmid. This led us to suggest that individual poly(dG)-poly(dC) molecules are immobilized on mica under ambient conditions in a form which is likely related to the A-form of DNA in contrast to poly(dA)-poly(dT) and random sequence DNA which are immobilized in a form that is related to the DNA B-form. 相似文献
104.
Inada NM da Silva AR Jorge RA Borecký J Vercesi AE 《Archives of biochemistry and biophysics》2007,457(2):217-224
The action of irradiated cationic Fe(III)TMPyP and anionic Fe(III)TPPS4 forms of mesoporphyrins on mitochondrial functions was investigated using experimental conditions that caused minimal effects on mitochondria in the dark. Treatment of mitochondria with 1 microM Fe(III)TMPyP for 2 min decreased the respiratory control by 3% in the dark and 28% after irradiation. Fe(III)TPPS4 (1 microM) had no significant effect on respiratory control under any of the above conditions. Both porphyrins increased the mitochondrial production of reactive oxygen species in the presence of Ca2+; however, the effect of Fe(III)TMPyP was significantly stronger. In both cases, this overproduction was associated with membrane lipid peroxidation. It was also observed that the association constant of Fe(III)TMPyP with mitochondria was 11 times higher than that of Fe(III)TPPS4. In conclusion, the damage to isolated mitochondria induced by Fe(III)TMPyP under illumination was larger than by Fe(III)TPPS4, probably because its cationic charge favors association with the mitochondrial membrane. This is supported by the decrease in the association constant of Fe(III)TMPyP with mitochondria in higher salt medium. 相似文献
105.
Magdalena Wysocka Anna Wojtysiak Małgorzata Okońska Natalia Gruba Mirosław Jarząb Tomasz Wenta Barbara Lipińska Reneta Grzywa Marcin Sieńczyk Krzysztof Rolka Adam Lesner 《Analytical biochemistry》2015
HtrA2 belongs to the HtrA (high temperature requirement A) family of ATP-independent serine proteases. The primary function of HtrA2 includes maintaining the mitochondria homeostasis, cell death (by apoptosis, necrosis, or anoikis), and contribution to the cell signaling. Several recent reports have shown involvement of HtrA2 in development of cancer and neurodegenerative disorders. Here, we describe the profiling of HtrA2 protease substrate specificity via the combinatorial chemistry approach that led to the selection of novel intramolecularly quenched substrates. For all synthesized compounds, the highest HtrA2-mediated hydrolysis efficiency and selectivity among tested HtrA family members was observed for ABZ-Ile-Met-Thr-Abu-Tyr-Met-Phe-Tyr(3-NO2)-NH2, which displayed a specificity constant kcat/KM value of 14,535 M−1 s−1. 相似文献
106.
Khromykh LM Kulikova NL Anfalova TV Muranova TA Abramov VM Vasiliev AM Khlebnikov VS Kazansky DB 《Cellular immunology》2007,249(1):46-53
Supernatant obtained from high dose hydrocortisone resistant thymocytes can induce migration of the bone marrow cell precursors to the periphery. This biological activity depends on the presence of the 18 kDa protein, whose amino acid sequence fits with the sequence of the secretory form of murine cyclophilin A (SP-18). Cyclophilin A isolated from the supernatant of the cortisone-resistant thymoma EL-4 shows its characteristic functional features as it demonstrates isomerase activity and binds with cyclosporine A. The cyclophilin A obtained manifests chemotactic activity that regulates migration of bone marrow cell precursors of neutrophils, T-, B- and dendritic cells. 相似文献
107.
108.
Rudenko NV Sinegina LL Arzhanov MA Ksenzenko VN Ivashina TV Morenkov OS Shaloiko LA Vinokurov LM 《Journal of biochemical and biophysical methods》2007,70(4):605-611
The effective new variant of "sandwich" bioluminescent enzyme immunoassay (BEIA) for the sensitive detection of glycoprotein B (gB) of pseudorabies virus (PrV) was presently developed. The high affinity interaction of barnase-barstar protein pair and photoprotein obelin as bioluminescent marker were for the first time successfully applied to BEIA development. Preliminary the two monoclonal antibodies, 11/5 and 34/2, were raised against gB for ELISA PrV detection. Presently we used the same immuno-"sandwich" principle for BEIA. To do this the two different bioconjugates were elaborated. Recombinant barnase was chemically conjugated with monoclonal anti-PrV's gB IgG, and also barstar was fused in frame to obelin. The characteristics of BEIA method have been compared to ELISA PrV detection. We have shown the proposed here gB-BEIA was 40-fold more sensitive as opposed to gB-ELISA test. The construction might have a broad promise in multiple potential immunological applications. 相似文献
109.
Natalia N. Ninkina Eugenia M. Privalova Luzia G. P. Pinn Alun M. Davies Vladimir L. Buchman 《Experimental cell research》1999,246(2):308
Synucleins constitute a group of unique, evolutionarily conserved proteins that are expressed predominantly in neurons of the central and peripheral nervous system. Although the normal cellular functions of synucleins are not clear, these proteins have been implicated in various neurodegenerative conditions in humans. We found that persyn, a recently characterized member of the synuclein family, is expressed not only in the nervous system but also in the stratum granulosum of the epidermis of neonatal and adult mice. This finding together with our recent observations that persyn influences neurofilament network integrity in sensory neurons raises the possibility that persyn in skin could be involved in modulation of the keratin network. 相似文献
110.
The activity and localization of fructose-1,6-bisphosphatase (FBPase; EC 3.1.3.11) in blood leukocytes of patients with type 1 diabetes mellitus and healthy adults were investigated immunocytochemically. The amount of polymorphonuclear (PMN) and mononuclear (MN) cells with positive FBPase immunocytochemical reaction was 57% and 68%, respectively, in pathological, and 38% and 42%, respectively, in healthy donors. Results of light microscopic investigations were confirmed by measurements of FBPase activity following lysis of PMN and MN cells. The enzyme activity of PMN and MN leukocytes was higher in diabetes mellitus than in healthy adults, by 30% and 127%, respectively. Using immunocytochemistry together with electron microscopy, FBPase was detected not only in the cytoplasm but also in the nucleus of leukocytes of both patients with insulin-dependent diabetes mellitus and healthy donors. 相似文献