全文获取类型
收费全文 | 913篇 |
免费 | 52篇 |
出版年
2023年 | 4篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 56篇 |
2014年 | 53篇 |
2013年 | 62篇 |
2012年 | 100篇 |
2011年 | 77篇 |
2010年 | 50篇 |
2009年 | 37篇 |
2008年 | 71篇 |
2007年 | 59篇 |
2006年 | 38篇 |
2005年 | 43篇 |
2004年 | 47篇 |
2003年 | 34篇 |
2002年 | 29篇 |
2001年 | 5篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 11篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1971年 | 1篇 |
1961年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有965条查询结果,搜索用时 31 毫秒
71.
Slc7a7 disruption causes fetal growth retardation by downregulating Igf1 in the mouse model of lysinuric protein intolerance 总被引:4,自引:0,他引:4
72.
73.
74.
Andrew M. Reynolds Jacopo G. Cecere Vitor H. Paiva Jaime A. Ramos Stefano Focardi 《Proceedings. Biological sciences / The Royal Society》2015,282(1811)
Homing studies have provided tantalizing evidence that the remarkable ability of shearwaters (Procellariiformes) to pinpoint their breeding colony after crossing vast expanses of featureless open ocean can be attributed to their assembling cognitive maps of wind-borne odours but crucially, it has not been tested whether olfactory cues are actually used as a system for navigation. Obtaining statistically important samples of wild birds for use in experimental approaches is, however, impossible because of invasive sensory manipulation. Using an innovative non-invasive approach, we provide strong evidence that shearwaters rely on olfactory cues for oceanic navigation. We tested for compliance with olfactory-cued navigation in the flight patterns of 210 shearwaters of three species (Cory''s shearwaters, Calonectris borealis, North Atlantic Ocean, Scopoli''s shearwaters, C. diomedea Mediterranean Sea, and Cape Verde shearwaters, C. edwardsii, Central Atlantic Ocean) tagged with high-resolution GPS loggers during both incubation and chick rearing. We found that most (69%) birds displayed exponentially truncated scale-free (Lévy-flight like) displacements, which we show are consistent with olfactory-cued navigation in the presence of atmospheric turbulence. Our analysis provides the strongest evidence yet for cognitive odour map navigation in wild birds. Thus, we may reconcile two highly disputed questions in movement ecology, by mechanistically connecting Lévy displacements and olfactory navigation. Our approach can be applied to any species which can be tracked at sufficient spatial resolution, using a GPS logger. 相似文献
75.
Rafael L. Rodríguez Jennifer Danzy Cramer Christopher A. Schmitt Tegan J. Gaetano J. Paul Grobler Nelson B. Freimer Trudy R. Turner 《Biological journal of the Linnean Society. Linnean Society of London》2015,114(3):527-537
Sexual traits vary tremendously in static allometry. This variation may be explained in part by body size‐related differences in the strength of selection. We tested this hypothesis in two populations of vervet monkeys, using estimates of the level of condition dependence for different morphological traits as a proxy for body size‐related variation in the strength of selection. In support of the hypothesis, we found that the steepness of allometric slopes increased with the level of condition dependence. One trait of particular interest, the penis, had shallow allometric slopes and low levels of condition dependence, in agreement with one of the most consistent patterns yet detected in the study of allometry, namely that of genitalia exhibiting shallow allometries. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 527–537. 相似文献
76.
77.
Lactoferrin (LF) is an iron-binding glycoprotein of the transferrin family, today known to have multifunctional physiological
activities. In humans, under normal conditions, LF has been found in blood, mucosal secretions, gastrointestinal fluids, urine
and mostly in milk and colostrum. The first pioneering immunohistochemical report about LF distribution in human tissues dated
in 1978; successively, many studies have been performed to analyze the LF immunohistochemical pattern in different normal
and neoplastic tissues. In this review, we present data from literature concerning the evidence of LF in tumors together with
those by us obtained during more than 25 years; the immunohistochemical applications to human neoplastic tissues have been
done to investigate the LF pathogenetic role as well as its activity in cancer. After a systematic analysis of LF immunoreactivity
in different human districts, a possible explanation for its presence and function has been modulated for each site or tissue,
according to experimental evidences obtained either by in vivo as well as by in vitro studies. 相似文献
78.
Synthesis and evaluation of quinoxaline derivatives as potential influenza NS1A protein inhibitors 总被引:1,自引:0,他引:1
You L Cho EJ Leavitt J Ma LC Montelione GT Anslyn EV Krug RM Ellington A Robertus JD 《Bioorganic & medicinal chemistry letters》2011,21(10):3007-3011
A library of quinoxaline derivatives were prepared to target non-structural protein 1 of influenza A (NS1A) as a means to develop anti-influenza drug leads. An in vitro fluorescence polarization assay demonstrated that these compounds disrupted the dsRNA-NS1A interaction to varying extents. Changes of substituent at positions 2, 3 and 6 on the quinoxaline ring led to variance in responses. The most active compounds (35 and 44) had IC50 values in the range of low micromolar concentration without exhibiting significant dsRNA intercalation. Compound 44 was able to inhibit influenza A/Udorn/72 virus growth. 相似文献
79.
Molecular replacement (MR) is widely used for addressing the phase problem in X-ray crystallography. Historically, crystallographers have had limited success using NMR structures as MR search models. Here, we report a comprehensive investigation of the utility of protein NMR ensembles as MR search models, using data for 25 pairs of X-ray and NMR structures solved and refined using modern NMR methods. Starting from NMR ensembles prepared by an improved protocol, FindCore, correct MR solutions were obtained for 22 targets. Based on these solutions, automatic model rebuilding could be done successfully. Rosetta refinement of NMR structures provided MR solutions for another two proteins. We also demonstrate that such properly prepared NMR ensembles and X-ray crystal structures have similar performance when used as MR search models for homologous structures, particularly for targets with sequence identity >40%. 相似文献
80.
The release of a potent bone-resorption inhibitor such as zoledronate from a versatile drug delivery system such as SBA 15
has been modeled. The initial and boundary conditions have been defined, together with the system parameters, including the
determination of equilibrium and transport parameters. Additionally, the experimental model of the same system has been observed
to validate the prediction here developed. This approach represents a powerful tool for the designing of mesoporous implantable
drug delivery systems because their release kinetics can be predicted in advance, and this leads to a considerable time and
resources saving. 相似文献