全文获取类型
收费全文 | 7809篇 |
免费 | 688篇 |
国内免费 | 1篇 |
专业分类
8498篇 |
出版年
2024年 | 5篇 |
2023年 | 34篇 |
2022年 | 89篇 |
2021年 | 155篇 |
2020年 | 92篇 |
2019年 | 116篇 |
2018年 | 156篇 |
2017年 | 118篇 |
2016年 | 255篇 |
2015年 | 434篇 |
2014年 | 472篇 |
2013年 | 518篇 |
2012年 | 682篇 |
2011年 | 733篇 |
2010年 | 500篇 |
2009年 | 380篇 |
2008年 | 538篇 |
2007年 | 515篇 |
2006年 | 454篇 |
2005年 | 433篇 |
2004年 | 411篇 |
2003年 | 350篇 |
2002年 | 379篇 |
2001年 | 73篇 |
2000年 | 44篇 |
1999年 | 73篇 |
1998年 | 88篇 |
1997年 | 60篇 |
1996年 | 48篇 |
1995年 | 22篇 |
1994年 | 29篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 22篇 |
1990年 | 15篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 10篇 |
1980年 | 6篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1967年 | 7篇 |
排序方式: 共有8498条查询结果,搜索用时 15 毫秒
101.
Human papillomavirus type 16 E7 peptide-directed CD8+ T cells from patients with cervical cancer are cross-reactive with the coronavirus NS2 protein 总被引:6,自引:0,他引:6 下载免费PDF全文
Nilges K Höhn H Pilch H Neukirch C Freitag K Talbot PJ Maeurer MJ 《Journal of virology》2003,77(9):5464-5474
Human papillomavirus type 16 (HPV16) E6 and E7 oncoproteins are required for cellular transformation and represent candidate targets for HPV-specific and major histocompatibility complex class I-restricted CD8(+)-T-cell responses in patients with cervical cancer. Recent evidence suggests that cross-reactivity represents the inherent nature of the T-cell repertoire. We identified HLA-A2 binding HPV16 E7 variant peptides from human, bacterial, or viral origin which are able to drive CD8(+)-T-cell responses directed against wild-type HPV16 E7 amino acid 11 to 19/20 (E7(11-19/20)) epitope YMLDLQPET(T) in vitro. CD8(+) T cells reacting to the HLA-A2-presented peptide from HPV16 E7(11-19(20)) recognized also the HLA-A2 binding peptide TMLDIQPED (amino acids 52 to 60) from the human coronavirus OC43 NS2 gene product. Establishment of coronavirus NS2-specific, HLA-A2-restricted CD8(+)-T-cell clones and ex vivo analysis of HPV16 E7 specific T cells obtained by HLA-A2 tetramer-guided sorting from PBL or tumor-infiltrating lymphocytes obtained from patients with cervical cancer showed that cross-reactivity with HPV16 E7(11-19(20)) and coronavirus NS2(52-60) represents a common feature of this antiviral immune response defined by cytokine production. Zero of 10 patients with carcinoma in situ neoplasia and 3 of 18 patients with cervical cancer showed > or =0.1% HPV16 E7-reactive T cells in CD8(+) peripheral blood lymphocytes. In vivo priming with HPV16 was confirmed in patients with cervical cancer or preinvasive HPV16-positive lesions using HLA-A2 tetramer complexes loaded with the E6-derived epitope KLPQLCTEL. In contrast, we could not detect E6-reactive T cells in healthy individuals. These data imply that the measurement of the HPV16 E7(11-19(20)) CD8(+)-T-cell response may reflect cross-reactivity with a common pathogen and that variant peptides may be employed to drive an effective cellular immune response against HPV. 相似文献
102.
Michael Denker Alexa Riehle Markus Diesmann Sonja Grün 《Journal of computational neuroscience》2010,29(3):599-613
The hypothesis that cortical networks employ the coordinated activity of groups of neurons, termed assemblies, to process
information is debated. Results from multiple single-unit recordings are not conclusive because of the dramatic undersampling
of the system. However, the local field potential (LFP) is a mesoscopic signal reflecting synchronized network activity. This
raises the question whether the LFP can be employed to overcome the problem of undersampling. In a recent study in the motor
cortex of the awake behaving monkey based on the locking of coincidences to the LFP we determined a lower bound for the fraction
of spike coincidences originating from assembly activation. This quantity together with the locking of single spikes leads
to a lower bound for the fraction of spikes originating from any assembly activity. Here we derive a statistical method to
estimate the fraction of spike synchrony caused by assemblies—not its lower bound—from the spike data alone. A joint spike
and LFP surrogate data model demonstrates consistency of results and the sensitivity of the method. Combining spike and LFP
signals, we obtain an estimate of the fraction of spikes resulting from assemblies in the experimental data. 相似文献
103.
J Schmitt C Backes N Nourkami-Tutdibi P Leidinger S Deutscher M Beier M Gessler N Graf HP Lenhof A Keller E Meese 《BMC genomics》2012,13(1):379
ABSTRACT: BACKGROUND: Blood-born miRNA signatures have recently been reported for various tumor diseases. Here, we compared themiRNA signature in Wilms tumor patients prior and after preoperative chemotherapy according to SIOPprotocol 2001. RESULTS: We did not find a significant difference between miRNA signature of both groups. However both, Wilmstumor patients prior and after chemotherapy showed a miRNA signature different from healthy controls. Thesignature of Wilms tumor patients prior to chemotherapy showed an accuracy of 97.5% and of patients afterchemotherapy an accuracy of 97.0%, each as compared to healthy controls. CONCLUSION: Our results provide evidence for a blood-born Wilms tumor miRNA signature largely independent of fourweeks preoperative chemotherapy treatment. 相似文献
104.
105.
Choimaa Dulamsuren Tobias Wommelsdorf Fengjun Zhao Yaoqin Xue Bulat Z. Zhumadilov Christoph Leuschner Markus Hauck 《Ecosystems》2013,16(8):1536-1549
The larch forests at the southern limit of the Siberian boreal forest in Central Asia have repeatedly experienced strong recent growth declines attributed to decreasing summer precipitation in the course of climate warming. Here, we present evidence from the southernmost Larix sibirica forests in eastern Kazakhstan that these declines are primarily caused by a decrease in effective moisture due to increasing summer temperatures, despite constant annual, and summer precipitation. Tree-ring chronologies (>800 trees) showed a reduction by 50–80% in mean ring width and an increase in the frequency of missing rings since the 1970s. Climate-response analysis revealed a stronger (negative) effect of summer temperature (in particular of the previous year’s June and July temperature) on radial growth than summer precipitation (positive effect). It is assumed that a rise in the atmospheric vapor pressure deficit, which typically increases with temperature, is negatively affecting tree water status and radial growth, either directly or indirectly through reduced soil moisture. Larch rejuvenation ceased in the 1950s, which is partly explained by increasing topsoil desiccation in a warmer climate and a high drought susceptibility of larch germination, as was demonstrated by a germination experiment with variable soil moisture levels. The lack of regeneration and the reduced annual stem increment suggest that sustainable forest management aiming at timber harvesting is no longer feasible in these southern boreal forests. Progressive climate warming is likely to cause a future northward shift of the southern limit of the boreal forest. 相似文献
106.
Hanno Würbel Markus Stauffacher Dietrich von Holst 《Ethology : formerly Zeitschrift fur Tierpsychologie》1996,102(3):371-385
The ontogeny of two stereotypic patterns, wire-gnawing and jumping, was studied in 24 laboratory mice: six males and six females each of two closely related outbred strains, kept under standard housing conditions, a conventional albino strain (ICR) and a nude, athymic mutant (ICR nu; hereafter: NU). All 24 individuals developed wire-gnawing after weaning at 20 d of age. In ICR one female and in NU five males and three females additionally developed jumping. ICR developed wire-gnawing between the age of 20 and 30 d, in NU jumping started at the age of 20 d, but intense jumping and wire-gnawing comparable to that of ICR did not develop in NU before the age of 40–50 d. Within each strain there was no significant difference between males and females with respect to the development of stereotypic behaviour. By contrast, ICR showed significantly more wire-gnawing but less jumping than NU. Stereotypy level increased with age up to a mean of 10.7 % of total activity in ICR and up to 7.4 % in NU at 100 d of age. However, there was huge inter- and intra-individual variability with respect to all parameters assessed in this study, i.e. total duration, number of bouts and bout length of the two stereotyped patterns. Wire-gnawing developed from outside-directed explorative climbing at the cage lid, whereas the source behaviour pattern (Mason 1991 a, Anim. Behav. 41, 1015–1037) of jumping was outside-directed explorative rearing at the cage wall. At 20 d of age, before the onset of stereotypy development, ICR showed significantly more climbing but less rearing than NU. Physical retardation of NU at weaning may account for decreased climbing ability during early ontogeny, and hence for the retarded development of wire-gnawing. The difference in early experience with either of the two patterns rather than genetic effects may be responsible for the qualitative difference between the strains with respect to the form of later stereotypy. 相似文献
107.
108.
Miles B Markus 《BMJ (Clinical research ed.)》1985,290(6481):1592
109.
Organisms in the wild are constantly faced with a wide range of environmental variability, such as fluctuation in food availability. Poor nutritional conditions influence life-histories via individual resource allocation patterns, and trade-offs between competing traits. In this study, we assessed the influence of food restriction during development on the energetically expensive traits flight metabolic rate (proxy of dispersal ability), encapsulation rate (proxy of immune defence), and lifespan using the Glanville fritillary butterfly, Melitaea cinxia, as a model organism. Additionally, we examined the direct costs of flight on individual immune function, and whether those costs increase under restricted environmental conditions. We found that nutritional restriction during development enhanced adult encapsulations rate, but reduced both resting and flight metabolic rates. However, at the individual level metabolic rates were not associated with encapsulation rate. Interestingly, individuals that were forced to fly prior to the immune assays had higher encapsulation rates than individuals that had not flown, suggesting that flying itself enhances immune response. Finally, in the control group encapsulation rate correlated positively with lifespan, whereas in the nutritional restriction group there was no relationship between these traits, suggesting that the association between encapsulation rate on adult lifespan was condition-dependent. Thus stressful events during both larval development (food limitation) and adulthood (forced flight) induce increased immune response in the adult butterflies, which may allow individuals to cope with stressful events later on in life. 相似文献
110.