全文获取类型
收费全文 | 561篇 |
免费 | 36篇 |
国内免费 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 35篇 |
2020年 | 21篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 21篇 |
2016年 | 23篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 52篇 |
2012年 | 49篇 |
2011年 | 41篇 |
2010年 | 29篇 |
2009年 | 26篇 |
2008年 | 27篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 19篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 3篇 |
2000年 | 8篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有598条查询结果,搜索用时 781 毫秒
561.
Feng Gao Mattia Bonsignori Hua-Xin Liao Amit Kumar Shi-Mao Xia Xiaozhi Lu Fangping Cai Kwan-Ki Hwang Hongshuo Song Tongqing Zhou Rebecca M. Lynch S. Munir Alam M. Anthony Moody Guido Ferrari Mark Berrong Garnett Kelsoe George M. Shaw Beatrice H. Hahn David C. Montefiori Gift Kamanga Myron S. Cohen Peter Hraber Peter D. Kwong Bette T. Korber John R. Mascola Thomas B. Kepler Barton F. Haynes 《Cell》2014
562.
Mattia Pierangelini Slobodanka Stojkovic Philip T. Orr John Beardall 《Journal of phycology》2014,50(2):292-302
We studied the growth and photosynthetic characteristics of a toxic (CS506) and a nontoxic strain (CS509) of the bloom‐forming cyanobacterium Cylindrospermopsis raciborskii grown under identical experimental conditions. When exposed to light‐saturating growth conditions (100 μmol photons · m?2 · s?1), values for maximal photosynthetic capacity (Pmax) and maximum quantum yield (Fv/Fm) indicated that both strains had an equal ability to process captured photons and deliver them to PSII reaction centers. However, CS506 grew faster than CS509. This was consistent with its higher light requirement for saturation of photosynthesis (Ik). Greater shade tolerance of CS509 was indicated by its higher ability to harvest light (α), lower photosynthetic light compensation point (Ic), and higher chlorophyll a to biovolume ratio. Strain‐specific differences were found in relation to non‐photochemical quenching, effective absorption cross‐sectional area of PSIIα‐centers (σPSIIα), and the antenna connectivity parameter of PSIIα (JconPSIIα). These findings highlighted differences in the transfer of excitation from phycobilisome/PSII to PSI, on the dependence on different pigments for light harvesting and on the functioning of the PSII reaction centers between the two strains. The results of this study showed that both performance and composition of the photosynthetic apparatus are different between these strains, though with only two strains examined we cannot attribute the performance of strain 506 to its ability to produce cylindrospermopsins. The emphasis on a strain‐specific light adaptation/acclimation is crucial to our understanding of how different light conditions (both quantity and quality) can trigger the occurrence of different C. raciborskii strains and control their competition and/or dominance in natural ecosystems. 相似文献
563.
Pinghuang Liu LaTonya D. Williams Xiaoying Shen Mattia Bonsignori Nathan A. Vandergrift R. Glenn Overman M. Anthony Moody Hua-Xin Liao Daniel J. Stieh Kerrie L. McCotter Audrey L. French Thomas J. Hope Robin Shattock Barton F. Haynes Georgia D. Tomaras 《Journal of virology》2014,88(9):5165-5170
Antibody capacity to recognize infectious virus is a prerequisite of many antiviral functions. We determined the infectious virion capture index (IVCI) of different antibody specificities. Whereas broadly neutralizing antibodies (bNAbs), except for an MPER bNAb, selectively captured infectious virions, non-bNAbs and mucosal human immunodeficiency virus type 1 (HIV-1)-positive IgG captured subsets of both infectious and noninfectious virions. Infectious virion capture was additive with a mixture of antibodies, providing proof of concept for vaccine-induced antibodies that together have improved capacity to recognize infectious virions. 相似文献
564.
A minimally invasive cardiac surgery is becoming more popular and is still undergoing a refinement of surgical techniques and dedicated instrumentarium as well. New specifically designed instruments are quintessence of safe surgery with improving operative outcomes and comfortable operator-oriented working conditions. In this article, we attempt to present our early clinical experience with a new aortic clamping instrument specifically developed for limited single-access minimally invasive valve surgery. 相似文献
565.
566.
Anne Turbé Diederik Strubbe Emiliano Mori Martina Carrete François Chiron Philippe Clergeau Pablo González‐Moreno Marine Le Louarn Alvaro Luna Mattia Menchetti Wolfgang Nentwig Liviu G. Pârâu Jose‐Luis Postigo Wolfgang Rabitsch Juan Carlos Senar Simon Tollington Sonia Vanderhoeven Anne Weiserbs Assaf Shwartz 《Diversity & distributions》2017,23(3):i-i
567.
Portaccio M De Luca P Durante D Grano V Rossi S Bencivenga U Lepore M Mita DG 《Bioelectromagnetics》2005,26(2):145-152
A study of the influence of electromagnetic fields (EMF) of various frequencies, from 50 up to 400 Hz, on the catalytic activity of soluble and insoluble horseradish peroxidase (POD) was carried out. To simulate the conditions in which the enzyme operates in vivo, the POD was immobilized by entrapment on a gelatin membrane or by covalent attachment on a nylon graft membrane. The rate of inactivation of the soluble POD was found to exhibit positive and negative interactions with the 1 mT applied magnetic field, with an optimum positive effect at 130 Hz. The immobilized PODs, on the contrary, do not exhibit negative interactions, but show a maximum positive interaction at 150 Hz when entrapped and at 170 Hz when covalently attached. At 50 Hz and at frequencies higher than 250 Hz no effects were observed with insoluble POD. The optimum frequency of positive interaction between the EMF and the catalytic activity of the insoluble enzymes is shifted with respect to that of the soluble enzymes towards higher frequencies, the size of the shifts being dependent on the intensity of the physical forces involved in the immobilization process. 相似文献
568.
Maximum growing depth of submerged macrophytes in European lakes 总被引:5,自引:0,他引:5
Martin Søndergaard Geoff Phillips Seppo Hellsten Agnieszka Kolada Frauke Ecke Helle Mäemets Marit Mjelde Mattia M. Azzella Alessandro Oggioni 《Hydrobiologia》2013,704(1):165-177
Submerged macrophytes are important elements for the structure and functioning of lake ecosystems. In this study, we used chemical and maximum colonisation depth (C_max) data from 12 European countries in order to investigate how suitable C_max may describe the impact by eutrophication. The analyses include data from 757 lakes and 919 lake years covering oligotrophic to eutrophic lakes. Overall, C_max was closely related to Secchi depth (R 2 = 0.58) and less closely to chlorophyll a (R 2 = 0.31), TP (R 2 = 0.31) and total nitrogen, TN (R 2 = 0.24). The low coefficients of determination between C_max and nutrient concentrations suggest that other response factors than nutrient-phytoplankton-light conditions are important for C_max and that it will be difficult to establish strong relationships between external nutrient loading and C_max. Yearly monitoring for 13–16 years in eight Danish lakes showed considerable year-to-year variability in C_max, which for the individual lakes only related weakly to changes in Secchi depth. The use of C_max as an eutrophication indicator is especially relevant in not very shallow lakes (maximum depth >4–5 m), not too turbid lakes (C_max >1 m) and not very humic lakes (colour <60 mg Pt/l). 相似文献
569.
Alessandro Stella Nicoletta Resta Angela Polizzi Mariapina Montera Filomena Cariola Francesco Susca Viviana Gismondi Lucio Bertario Cristiana Marchese Romano Tenconi Maria Grazia Tibiletti Paola Izzo Mattia Gentile Fernando Prete Oronzo Pannarale Giovanni Di Matteo Paola Sala Liliana Varesco Cristina Mareni G. Guanti 《Human genetics》1998,102(6):624-628
In the present study, we used five different polymorphic markers to construct the haplotype at the adenomatous polyposis
coli (APC) locus in families with familial adenomatous polyposis (FAP) and in the normal Italian population. Non-ambiguous
haplotypes were reconstructed from 246 normal chromosomes and 65 FAP chromosomes. In the control population, the four polymorphisms
intragenic to APC gave rise to 16 haplotypes, the most common of which (II and XV) accounted for over 50% of all chromosomes.
In FAP patients, 13 haplotypes were found but their distribution was not statistically different from normal subjects. Eighty
complete chromosomal haplotypes (many fewer than the theoretical maximum of 208) for the five polymorphic sites assayed were
observed in the control population, 35 being found in the FAP patients. We compared the distribution of these haplotypes within
the two groups; no statistically significant differences between normal and FAP chromosomes were found. The elevated heterogeneity
of FAP chromosomes was clearly confirmed by the observation that 19 patients who carried one or other of the two most common
APC mutations (nt 3183 and nt 3927) showed 18 different haplotypes. On the basis of these results, we were not able to identify
a founder FAP chromosome. Various mechanisms are presented to explain this observation.
Received: 5 November 1997 / Accepted: 3 February 1998 相似文献
570.