全文获取类型
收费全文 | 8003篇 |
免费 | 767篇 |
国内免费 | 1篇 |
出版年
2021年 | 116篇 |
2020年 | 59篇 |
2019年 | 100篇 |
2018年 | 101篇 |
2017年 | 107篇 |
2016年 | 186篇 |
2015年 | 271篇 |
2014年 | 303篇 |
2013年 | 345篇 |
2012年 | 423篇 |
2011年 | 433篇 |
2010年 | 283篇 |
2009年 | 259篇 |
2008年 | 379篇 |
2007年 | 368篇 |
2006年 | 328篇 |
2005年 | 351篇 |
2004年 | 337篇 |
2003年 | 320篇 |
2002年 | 292篇 |
2001年 | 179篇 |
2000年 | 180篇 |
1999年 | 138篇 |
1998年 | 90篇 |
1997年 | 81篇 |
1996年 | 63篇 |
1995年 | 63篇 |
1994年 | 57篇 |
1993年 | 78篇 |
1992年 | 130篇 |
1991年 | 135篇 |
1990年 | 141篇 |
1989年 | 127篇 |
1988年 | 121篇 |
1987年 | 92篇 |
1986年 | 100篇 |
1985年 | 115篇 |
1984年 | 93篇 |
1983年 | 84篇 |
1982年 | 73篇 |
1981年 | 63篇 |
1980年 | 60篇 |
1979年 | 88篇 |
1978年 | 66篇 |
1977年 | 74篇 |
1976年 | 68篇 |
1975年 | 68篇 |
1974年 | 58篇 |
1973年 | 67篇 |
1971年 | 55篇 |
排序方式: 共有8771条查询结果,搜索用时 281 毫秒
991.
Han GW Sri Krishna S Schwarzenbacher R McMullan D Ginalski K Elsliger MA Brittain SM Abdubek P Agarwalla S Ambing E Astakhova T Axelrod H Canaves JM Chiu HJ DiDonato M Grzechnik SK Hale J Hampton E Haugen J Jaroszewski L Jin KK Klock HE Knuth MW Koesema E Kreusch A Kuhn P Miller MD Morse AT Moy K Nigoghossian E Oommachen S Ouyang J Paulsen J Quijano K Reyes R Rife C Spraggon G Stevens RC van den Bedem H Velasquez J Wang X West B White A Wolf G Xu Q Hodgson KO Wooley J Deacon AM Godzik A 《Proteins》2006,64(4):1083-1090
992.
Xu Q Krishna SS McMullan D Schwarzenbacher R Miller MD Abdubek P Agarwalla S Ambing E Astakhova T Axelrod HL Canaves JM Carlton D Chiu HJ Clayton T DiDonato M Duan L Elsliger MA Feuerhelm J Grzechnik SK Hale J Hampton E Han GW Haugen J Jaroszewski L Jin KK Klock HE Knuth MW Koesema E Kreusch A Kuhn P Morse AT Nigoghossian E Okach L Oommachen S Paulsen J Quijano K Reyes R Rife CL Spraggon G Stevens RC van den Bedem H White A Wolf G Hodgson KO Wooley J Deacon AM Godzik A Lesley SA Wilson IA 《Proteins》2006,65(3):777-782
993.
DiDonato M Krishna SS Schwarzenbacher R McMullan D Agarwalla S Brittain SM Miller MD Abdubek P Ambing E Axelrod HL Canaves JM Chiu HJ Deacon AM Duan L Elsliger MA Godzik A Grzechnik SK Hale J Hampton E Haugen J Jaroszewski L Jin KK Klock HE Knuth MW Koesema E Kreusch A Kuhn P Lesley SA Levin I Morse AT Nigoghossian E Okach L Oommachen S Paulsen J Quijano K Reyes R Rife CL Spraggon G Stevens RC van den Bedem H White A Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2006,65(3):771-776
994.
Lu S Yao Y Cheng X Mitchell S Leng S Meng S Gallagher JW Shelness GS Morris GS Mahan J Frase S Mansbach CM Weinberg RB Black DD 《The Journal of biological chemistry》2006,281(6):3473-3483
Intestinal apolipoprotein A-IV expression is highly regulated by dietary lipid in newborn swine, suggesting a role in lipid absorption. Constitutive overexpression of apoA-IV in newborn swine enterocytes enhances basolateral secretion of triacylglycerol (TG) in TG-rich lipoproteins 4.9-fold (Lu, S., Yao, Y., Meng, S., Cheng, X., and Black, D. D. (2002) J. Biol. Chem. 277, 31929-31937). To investigate the mechanism of this enhancement, IPEC-1 cells were transfected with a tetracycline-regulatable expression system (Tet-On). In cells incubated with oleic acid, a dose response relationship was observed between medium doxycycline concentration and basolateral apoA-IV and TG secretion. Similarly regulated expression of apoA-I did not enhance lipid secretion. The mean diameter of TG-rich lipoproteins secreted from doxycycline-treated cells was larger than from untreated cells (87.0 nm versus 53.4 nm). Basolateral apoB secretion decreased. Using the same expression system, full-length human apoA-IV (376 amino acids); a "pig-like" human apoA-IV, lacking the C-terminal EQQQ repeats (361 amino acids); and a "chicken-like" apoA-IV, further truncated to 343 amino acids, were expressed in IPEC-1 cells. With increasing protein secretion, cells expressing the full-length human apoA-IV displayed a 2-fold increase in TG secretion; in sharp contrast, cells expressing the pig-like human apoA-IV displayed a 25-fold increase in TG secretion and a 27-fold increase in lipoprotein diameter. When human apoA-IV was further truncated to yield a chicken-like protein, TG secretion was inhibited. We conclude that overexpression of swine apoA-IV enhances basolateral TG secretion in a dose-dependent manner by increasing the size of secreted lipoproteins. These data suggest that the region in the human apoA-IV protein from residues 344 to 354 is critical to its ability to enhance lipid secretion, perhaps by enabling the packaging of additional core TG into chylomicron particles. The EQQQ-rich region may play an inhibitory or modulatory role in chylomicron packaging in humans. 相似文献
995.
996.
997.
Innate defense against influenza A virus: activity of human neutrophil defensins and interactions of defensins with surfactant protein D 总被引:4,自引:0,他引:4
Hartshorn KL White MR Tecle T Holmskov U Crouch EC 《Journal of immunology (Baltimore, Md. : 1950)》2006,176(11):6962-6972
Surfactant protein D (SP-D) plays important roles in innate host defense against influenza A virus (IAV) infection, in part by modifying interactions with neutrophils. Human neutrophil defensins (HNPs) inhibit infectivity of enveloped viruses, including IAV. Our goal in this study was to characterize antiviral interactions between SP-D and HNPs. Recombinant and/or natural forms of SP-D and related collectins and HNPs were tested for antiviral activity against two different strains of IAV. HNPs 1 and 2 did not inhibit viral hemagglutination activity, but they interfered with the hemagglutination-inhibiting activity of SP-D. HNPs had significant viral neutralizing activity against divergent IAV strains. However, the HNPs generally had competitive effects when combined with SP-D in assays using an SP-D-sensitive IAV strain. In contrast, cooperative antiviral effects were noted in some instances when relatively SP-D-resistant strains were treated with SP-D and HNPs. HNPs were found to bind to the neck and/or carbohydrate recognition domain of SP-D. This binding was specific because no, or minimal, binding to other collectins was found. HNPs precipitated SP-D from bronchoalveolar lavage fluid and reduced the antiviral activity of bronchoalveolar lavage fluid. HNP-1 and -2 differed somewhat in their independent antiviral activity and their binding to SP-D. These results are relevant to the early phase of host defense against IAV, and suggest a complex interplay between SP-D and HNPs at sites of active inflammation. 相似文献
998.
Célia V. Romão Edward P. Mitchell Sean McSweeney 《Journal of biological inorganic chemistry》2006,11(7):891-902
The crystal structure of a DNA-binding protein from starved cells (Dps) (DR2263) from Deinococcus radiodurans was determined in two states: a native form, to 1.1-Å resolution, and one soaked in an iron solution, to 1.6-Å resolution. In comparison with other Dps proteins, DR2263 has an extended N-terminal extension, in both structures presented here, a novel metal binding site was identified in this N-terminal extension and was assigned to bound zinc. The zinc is tetrahedrally coordinated and the ligands, that belong to the N-terminal extension, are two histidines, one glutamate and one aspartate residue, which are unique to this protein within the Dps family. In the iron-soaked crystal structure, a total of three iron sites per monomer were found: one site corresponds to the ferroxidase centre with structural similarities to those found in other Dps family members; the two other sites are located on the two different threefold axes corresponding to small pores in the Dps sphere, which may possibly form the entrance and exit channels for iron storage. 相似文献
999.
1000.
It has been postulated that the progression of a pregnancy to term is, in part, the result of a relative maternal Th2 immunological state. Prostaglandins (PG) are critical mediators throughout pregnancy. Recent studies have demonstrated that one PG, PGD2, may be a mediator of a Th2 immunological state. To date, very little is known about the factors that regulate of PGD2 production by human gestational tissues. Placentae were collected from women undergoing Caesarean sections at term. Amnion was separated from the choriodecidua and choriodecidual explants established. Explants were allowed to equilibrate overnight in media containing 10% fetal calf serum. The following day, media were replaced with serum free media and then after an additional 24-h, media were collected and the wet weight of the tissues determined. Production rates of PGs were determined using radioimmunoassays. At all concentrations tested, LPS significantly enhanced PGD2 production by human choriodecidual explants compared to PGE2 and PGF2alpha production. Neutralization of TNF-alpha and IL-10 further increased the production of LPS stimulated PGD2 production. We suggest that a novel stimulatory pathway that drives the production of PGD2 has been uncovered. 相似文献