全文获取类型
收费全文 | 249篇 |
免费 | 0篇 |
国内免费 | 2篇 |
专业分类
系统科学 | 1篇 |
教育与普及 | 1篇 |
理论与方法论 | 2篇 |
现状及发展 | 28篇 |
研究方法 | 50篇 |
综合类 | 161篇 |
自然研究 | 8篇 |
出版年
2017年 | 1篇 |
2016年 | 2篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 27篇 |
2011年 | 40篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 23篇 |
2007年 | 27篇 |
2006年 | 18篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 17篇 |
2002年 | 18篇 |
1987年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1971年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1959年 | 4篇 |
1958年 | 2篇 |
排序方式: 共有251条查询结果,搜索用时 15 毫秒
211.
In 1983 zinc phosphide, strychnine with prebait, and strychnine without prebait were applied to black-tailed prairie dog ( Cynomys ludovicianus ) colonies in west central South Dakota. Short-term (four days later) and long-term (one year later) impacts of the rodenticides on Horned Larks ( Eremophila alpestris ) and other granivorous birds inhabiting prairie dog colonies were evaluated. Hrned Larks and 49 other bird species were observed. Immediate impacts reduced Horned Lark relative densities 66% with strychnine only and 55% with prebaited strychnine. Zinc phosphide caused no measurable reduction. Horned Larks showed no long-term direct impacts. Indirect negative impacts occurred through habitat changes following prairie dog control. The granivorous guild showed no short- or long-term effects. 相似文献
212.
Barton A Thomson W Ke X Eyre S Hinks A Bowes J Plant D Gibbons LJ;Wellcome Trust Case Control Consortium;YEAR Consortium;BIRAC Consortium Wilson AG Bax DE Morgan AW Emery P Steer S Hocking L Reid DM Wordsworth P Harrison P Worthington J 《Nature genetics》2008,40(10):1156-1159
The WTCCC study identified 49 SNPs putatively associated with rheumatoid arthritis at P = 1 x 10(-4) - 1 x 10(-5) (tier 3). Here we show that three of these SNPs, mapping to chromosome 10p15 (rs4750316), 12q13 (rs1678542) and 22q13 (rs3218253), are also associated (trend P = 4 x 10(-5), P = 4 x 10(-4) and P = 4 x 10(-4), respectively) in a validation study of 4,106 individuals with rheumatoid arthritis and an expanded reference group of 11,238 subjects, confirming them as true susceptibility loci in individuals of European ancestry. 相似文献
213.
Broderick P Chubb D Johnson DC Weinhold N Försti A Lloyd A Olver B Ma YP Dobbins SE Walker BA Davies FE Gregory WA Child JA Ross FM Jackson GH Neben K Jauch A Hoffmann P Mühleisen TW Nöthen MM Moebus S Tomlinson IP Goldschmidt H Hemminki K Morgan GJ Houlston RS 《Nature genetics》2012,44(1):58-61
To identify risk variants for multiple myeloma, we conducted a genome-wide association study of 1,675 individuals with multiple myeloma and 5,903 control subjects. We identified risk loci for multiple myeloma at 3p22.1 (rs1052501 in ULK4; odds ratio (OR) = 1.32; P = 7.47 × 10(-9)) and 7p15.3 (rs4487645, OR = 1.38; P = 3.33 × 10(-15)). In addition, we observed a promising association at 2p23.3 (rs6746082, OR = 1.29; P = 1.22 × 10(-7)). Our study identifies new genomic regions associated with multiple myeloma risk that may lead to new etiological insights. 相似文献
214.
Daniel W. Lambert Nicola E. Clarke Anthony J. Turner 《Cellular and molecular life sciences : CMLS》2010,67(1):89-98
The renin-angiotensin system (RAS) is a critical regulator of blood pressure and fluid homeostasis. Angiotensin II, the primary
bioactive peptide of the RAS, is generated from angiotensin I by angiotensin-converting enzyme (ACE). A homologue of ACE,
ACE2, is able to convert angiotensin II to a peptide with opposing effects, angiotensin-(1-7). It is proposed that disturbance
of the balance of ACE and ACE2 expression and/or function is important in pathologies in which angiotensin II plays a role.
These include cardiovascular and renal disease, lung injury and liver fibrosis. The critical roles of ACE and ACE2 in regulating
angiotensin II levels have traditionally focussed attention on their activities as angiotensinases. Recent discoveries, however,
have illuminated the roles of these enzymes and of the ACE2 homologue, collectrin, in intracellular trafficking and signalling.
This paper reviews the key literature regarding both the catalytic and non-catalytic roles of the angiotensin-converting enzyme
gene family. 相似文献
215.
Kras is the most frequently mutated ras family member in lung carcinomas, whereas Hras mutations are common in tumors from stratified epithelia such as the skin. Using a Hras knock-in mouse model, we demonstrate that specificity for Kras mutations in lung and Hras mutations in skin tumors is determined by local regulatory elements in the target ras genes. Although the Kras 4A isoform is dispensable for mouse development, it is the most important isoform for lung carcinogenesis in vivo and for the inhibitory effect of wild-type (WT) Kras on the mutant allele. Kras 4A expression is detected in a subpopulation of normal lung epithelial cells, but at very low levels in lung tumors, suggesting that it may not be required for tumor progression. The two Kras isoforms undergo different post-translational modifications; therefore, these findings can have implications for the design of therapeutic strategies for inhibiting oncogenic Kras activity in human cancers. 相似文献
216.
Jin Y Birlea SA Fain PR Ferrara TM Ben S Riccardi SL Cole JB Gowan K Holland PJ Bennett DC Luiten RM Wolkerstorfer A van der Veen JP Hartmann A Eichner S Schuler G van Geel N Lambert J Kemp EH Gawkrodger DJ Weetman AP Taïeb A Jouary T Ezzedine K Wallace MR McCormack WT Picardo M Leone G Overbeck A Silverberg NB Spritz RA 《Nature genetics》2012,44(6):676-680
We previously reported a genome-wide association study (GWAS) identifying 14 susceptibility loci for generalized vitiligo. We report here a second GWAS (450 individuals with vitiligo (cases) and 3,182 controls), an independent replication study (1,440 cases and 1,316 controls) and a meta-analysis (3,187 cases and 6,723 controls) identifying 13 additional vitiligo-associated loci. These include OCA2-HERC2 (combined P = 3.80 × 10(-8)), MC1R (P = 1.82 × 10(-13)), a region near TYR (P = 1.57 × 10(-13)), IFIH1 (P = 4.91 × 10(-15)), CD80 (P = 3.78 × 10(-10)), CLNK (P = 1.56 × 10(-8)), BACH2 (P = 2.53 × 10(-8)), SLA (P = 1.58 × 10(-8)), CASP7 (P = 3.56 × 10(-8)), CD44 (P = 1.78 × 10(-9)), IKZF4 (P = 2.75 × 10(-14)), SH2B3 (P = 3.54 × 10(-18)) and TOB2 (P = 6.81 × 10(-10)). Most vitiligo susceptibility loci encode immunoregulatory proteins or melanocyte components that likely mediate immune targeting and the relationships among vitiligo, melanoma, and eye, skin and hair coloration. 相似文献
217.
Eisenbarth SC Williams A Colegio OR Meng H Strowig T Rongvaux A Henao-Mejia J Thaiss CA Joly S Gonzalez DG Xu L Zenewicz LA Haberman AM Elinav E Kleinstein SH Sutterwala FS Flavell RA 《Nature》2012,484(7395):510-513
NLRs (nucleotide-binding domain leucine-rich-repeat-containing receptors; NOD-like receptors) are a class of pattern recognition receptor (PRR) that respond to host perturbation from either infectious agents or cellular stress. The function of most NLR family members has not been characterized and their role in instructing adaptive immune responses remains unclear. NLRP10 (also known as PYNOD, NALP10, PAN5 and NOD8) is the only NLR lacking the putative ligand-binding leucine-rich-repeat domain, and has been postulated to be a negative regulator of other NLR members, including NLRP3 (refs 4-6). We did not find evidence that NLRP10 functions through an inflammasome to regulate caspase-1 activity nor that it regulates other inflammasomes. Instead, Nlrp10(-/-) mice had a profound defect in helper T-cell-driven immune responses to a diverse array of adjuvants, including lipopolysaccharide, aluminium hydroxide and complete Freund's adjuvant. Adaptive immunity was impaired in the absence of NLRP10 because of a dendritic cell (DC) intrinsic defect in emigration from inflamed tissues, whereas upregulation of DC costimulatory molecules and chemotaxis to CCR7-dependent and -independent ligands remained intact. The loss of antigen transport to the draining lymph nodes by a subset of migratory DCs resulted in an almost absolute loss in naive CD4(+) T-cell priming, highlighting the critical link between diverse innate immune stimulation, NLRP10 activity and the immune function of mature DCs. 相似文献
218.
Approaching a state shift in Earth's biosphere 总被引:1,自引:0,他引:1
Barnosky AD Hadly EA Bascompte J Berlow EL Brown JH Fortelius M Getz WM Harte J Hastings A Marquet PA Martinez ND Mooers A Roopnarine P Vermeij G Williams JW Gillespie R Kitzes J Marshall C Matzke N Mindell DP Revilla E Smith AB 《Nature》2012,486(7401):52-58
Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Here we review evidence that the global ecosystem as a whole can react in the same way and is approaching a planetary-scale critical transition as a result of human influence. The plausibility of a planetary-scale 'tipping point' highlights the need to improve biological forecasting by detecting early warning signs of critical transitions on global as well as local scales, and by detecting feedbacks that promote such transitions. It is also necessary to address root causes of how humans are forcing biological changes. 相似文献
219.
Global Positioning System (GPS) measurements at subduction plate boundaries often record fault movements similar to earthquakes but much slower, occurring over timescales of approximately 1 week to approximately 1 year. These 'slow slip events' have been observed in Japan, Cascadia, Mexico, Alaska and New Zealand. The phenomenon is poorly understood, but several observations hint at the processes underlying slow slip. Although slip itself is silent, seismic instruments often record coincident low-amplitude tremor in a narrow (1-5 cycles per second) frequency range. Also, modelling of GPS data and estimates of tremor location indicate that slip focuses near the transition from unstable ('stick-slip') to stable friction at the deep limit of the earthquake-producing seismogenic zone. Perhaps most intriguingly, slow slip is periodic at several locations, with recurrence varying from 6 to 18 months depending on which subduction zone (or even segment) is examined. Here I show that such periodic slow fault slip may be a resonant response to climate-driven stress perturbations. Fault slip resonance helps to explain why slip events are periodic, why periods differ from place to place, and why slip focuses near the base of the seismogenic zone. Resonant slip should initiate within the rupture zone of future great earthquakes, suggesting that slow slip may illuminate fault properties that control earthquake slip. 相似文献
220.
ZHAOYunjie XUESaifeng ZHUQianjiang TAOZhu ZHANGJianxin WEIZhanbin LONGLasheng HUMaolin XiaoHongping DAYAnthony 《科学通报(英文版)》2004,49(11):1111-1116
Synthesis of a symmetrical tetrasubstituted cucurbit[6]uril has been achieved by using the diether of dimethylglycoluril (1) and the dimmer of glycoluril (2). The structure of the symmetrical tetramethylcucurbit[6]uril (TMeQ[6]) has been determined by single crystal X-ray diffraction, ^1H NMR spectroscopy and ESMS. The ^1H NMR spectra of 2,2‘-bipyridine added to TMeQ[6] reveal that the host-guest inclusion complex was easily formed. 相似文献