全文获取类型
收费全文 | 1139篇 |
免费 | 100篇 |
国内免费 | 1篇 |
出版年
2022年 | 19篇 |
2021年 | 23篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 19篇 |
2016年 | 35篇 |
2015年 | 50篇 |
2014年 | 49篇 |
2013年 | 52篇 |
2012年 | 73篇 |
2011年 | 76篇 |
2010年 | 43篇 |
2009年 | 40篇 |
2008年 | 46篇 |
2007年 | 49篇 |
2006年 | 60篇 |
2005年 | 46篇 |
2004年 | 52篇 |
2003年 | 38篇 |
2002年 | 41篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1990年 | 12篇 |
1989年 | 9篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1974年 | 7篇 |
1972年 | 7篇 |
1969年 | 9篇 |
1968年 | 9篇 |
1967年 | 7篇 |
1962年 | 7篇 |
1961年 | 6篇 |
排序方式: 共有1240条查询结果,搜索用时 140 毫秒
951.
Gisela Berth Herbert Dautzenberg Bjrn E. Christensen Gudrun Rother Olav Smidsrd 《Biopolymers》1996,39(5):709-719
Laboratory-made samples of the polysaccharide xylinan (acetan) were fractionated on Sepharose Cl-2B using 0.1M NaCl as eluant. The weight average molar masses and intrinsic viscosities were estimated in the fractions by multiangle laser light scattering (off-line) and capillary viscometry, respectively. The Mark-Houwink-Sakurada plot was found to be indicative of semiflexible coils (a = 0.90). The angular dependence of scattered light was interpreted by fitting with theoretically calculated “Master Curves” in terms of a wormlike chain model. The ambiguity of the interpretation of scattering curves owing to the overlapping effects of chain stiffness and polydispersity is discussed in detail. The experimental data is found to be consistent with a persistence length of Lp = 100 nm. The main proportion consists of double-stranded chains (consistent with a robust double-helix), but single- and multistranded chains also are present. Our results suggest a fractionation according to the contour length rather than the molar mass. © 1996 John Wiley & Sons, Inc. 相似文献
952.
953.
954.
Öffnen der Stomata bei hoher Temperatur im Dunkeln 总被引:1,自引:0,他引:1
955.
Eric Lewitus Samantha M. Townsley Yifan Li Gina C. Donofrio Bethany L. Dearlove Hongjun Bai Eric Sanders-Buell Anne Marie OSullivan Meera Bose Hannah Kibuuka Lucas Maganga Sorachai Nitayaphan Fredrick K. Sawe Leigh Anne Eller Nelson L. Michael Victoria R. Polonis Julie A. Ake Sandhya Vasan Merlin L. Robb Sodsai Tovanabutra Shelly J. Krebs Morgane Rolland 《PLoS pathogens》2022,18(3)
Eliciting broadly neutralizing antibodies (bnAbs) is a cornerstone of HIV-1 vaccine strategies. Comparing HIV-1 envelope (env) sequences from the first weeks of infection to the breadth of antibody responses observed several years after infection can help define viral features critical to vaccine design. We investigated the relationship between HIV-1 env genetics and the development of neutralization breadth in 70 individuals enrolled in a prospective acute HIV-1 cohort. Half of the individuals who developed bnAbs were infected with multiple HIV-1 founder variants, whereas all individuals with limited neutralization breadth had been infected with single HIV-1 founders. Accordingly, at HIV-1 diagnosis, env diversity was significantly higher in participants who later developed bnAbs compared to those with limited breadth (p = 0.012). This association between founder multiplicity and the subsequent development of neutralization breadth was also observed in 56 placebo recipients in the RV144 vaccine efficacy trial. In addition, we found no evidence that neutralization breath was heritable when analyzing env sequences from the 126 participants. These results demonstrate that the presence of slightly different HIV-1 variants in acute infection could promote the induction of bnAbs, suggesting a novel vaccine strategy, whereby an initial immunization with a cocktail of minimally distant antigens would be able to initiate bnAb development towards breadth. 相似文献
956.
Davide Danovi Catherine A. Cremona Gisela Machado-da-Silva Sreya Basu Luke A. Noon Simona Parrinello Alison C. Lloyd 《PloS one》2010,5(7)
Anchorage-independent proliferation is a hallmark of oncogenic transformation and is thought to be conducive to proliferation of cancer cells away from their site of origin. We have previously reported that primary Schwann cells expressing the SV40 Large T antigen (LT) are not fully transformed in that they maintain a strict requirement for attachment, requiring a further genetic change, such as oncogenic Ras, to gain anchorage-independence. Using the LT-expressing cells, we performed a genetic screen for anchorage-independent proliferation and identified Sensory and Motor Neuron Derived Factor (SMDF), a transmembrane class III isoform of Neuregulin 1. In contrast to oncogenic Ras, SMDF induced enhanced proliferation in normal primary Schwann cells but did not trigger cellular senescence. In cooperation with LT, SMDF drove anchorage-independent proliferation, loss of contact inhibition and tumourigenicity. This transforming ability was shared with membrane-bound class III but not secreted class I isoforms of Neuregulin, indicating a distinct mechanism of action. Importantly, we show that despite being membrane-bound signalling molecules, class III neuregulins transform via a cell intrinsic mechanism, as a result of constitutive, elevated levels of ErbB signalling at high cell density and in anchorage-free conditions. This novel transforming mechanism may provide new targets for cancer therapy. 相似文献
957.
Gisela Ernst-Slavit 《Anthropology & education quarterly》1997,28(2):311-312
Teacher Thinking in Cultural Contexts. Francisco A. Rios, ed. Albany: State University of New York Press, 1996. 400 pp. 相似文献
958.
Gisela Mosig 《Molecular & general genetics : MGG》1960,91(2):164-181
Ohne ZusammenfassungTeil einer Dissertation, die bei der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Köln eingereicht wurde. 相似文献
959.
Ohne ZusammenfassungIII. Mitteilung: Franke, W., G. Jilge u. G. Eichhorn: Arch. Mikrobiol. 39, 95 (1961).Herrn Prof. Hans von Euler, Stockholm, zum 90. Geburtstage gewidmet. 相似文献
960.