全文获取类型
收费全文 | 664篇 |
免费 | 3篇 |
国内免费 | 5篇 |
专业分类
系统科学 | 10篇 |
教育与普及 | 2篇 |
理论与方法论 | 5篇 |
现状及发展 | 252篇 |
研究方法 | 104篇 |
综合类 | 288篇 |
自然研究 | 11篇 |
出版年
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 14篇 |
2012年 | 51篇 |
2011年 | 62篇 |
2010年 | 26篇 |
2009年 | 9篇 |
2008年 | 38篇 |
2007年 | 31篇 |
2006年 | 40篇 |
2005年 | 32篇 |
2004年 | 45篇 |
2003年 | 34篇 |
2002年 | 31篇 |
2001年 | 11篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1995年 | 3篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1974年 | 3篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1971年 | 6篇 |
1970年 | 6篇 |
1969年 | 6篇 |
1968年 | 4篇 |
1967年 | 3篇 |
1966年 | 3篇 |
1965年 | 2篇 |
1964年 | 3篇 |
1955年 | 5篇 |
排序方式: 共有672条查询结果,搜索用时 15 毫秒
11.
Bedding TR Mosser B Huber D Montalbán J Beck P Christensen-Dalsgaard J Elsworth YP García RA Miglio A Stello D White TR De Ridder J Hekker S Aerts C Barban C Belkacem K Broomhall AM Brown TM Buzasi DL Carrier F Chaplin WJ Di Mauro MP Dupret MA Frandsen S Gilliland RL Goupil MJ Jenkins JM Kallinger T Kawaler S Kjeldsen H Mathur S Noels A Aguirre VS Ventura P 《Nature》2011,471(7340):608-611
Red giants are evolved stars that have exhausted the supply of hydrogen in their cores and instead burn hydrogen in a surrounding shell. Once a red giant is sufficiently evolved, the helium in the core also undergoes fusion. Outstanding issues in our understanding of red giants include uncertainties in the amount of mass lost at the surface before helium ignition and the amount of internal mixing from rotation and other processes. Progress is hampered by our inability to distinguish between red giants burning helium in the core and those still only burning hydrogen in a shell. Asteroseismology offers a way forward, being a powerful tool for probing the internal structures of stars using their natural oscillation frequencies. Here we report observations of gravity-mode period spacings in red giants that permit a distinction between evolutionary stages to be made. We use high-precision photometry obtained by the Kepler spacecraft over more than a year to measure oscillations in several hundred red giants. We find many stars whose dipole modes show sequences with approximately regular period spacings. These stars fall into two clear groups, allowing us to distinguish unambiguously between hydrogen-shell-burning stars (period spacing mostly ~ 50 seconds) and those that are also burning helium (period spacing ~ 100 to 300 seconds). 相似文献
12.
Sensory information is transmitted to the brain where it must be processed to translate stimulus features into appropriate behavioural output. In the olfactory system, distributed neural activity in the nose is converted into a segregated map in the olfactory bulb. Here we investigate how this ordered representation is transformed in higher olfactory centres in mice. We have developed a tracing strategy to define the neural circuits that convey information from individual glomeruli in the olfactory bulb to the piriform cortex and the cortical amygdala. The spatial order in the bulb is discarded in the piriform cortex; axons from individual glomeruli project diffusely to the piriform without apparent spatial preference. In the cortical amygdala, we observe broad patches of projections that are spatially stereotyped for individual glomeruli. These projections to the amygdala are overlapping and afford the opportunity for spatially localized integration of information from multiple glomeruli. The identification of a distributive pattern of projections to the piriform and stereotyped projections to the amygdala provides an anatomical context for the generation of learned and innate behaviours. 相似文献
13.
14.
1 Results Electroactive polymers (EAPs) driven by transducing electric energy into mechanical energy have been the subjects of recent interest[1].“Ionic liquids“,consisting entirely of cation and anion,have characteristic features such as negligible volatility,non-flammability,thermal and chemical stability,and high ionic conductivity.We proposed an EAP actuator utilizing ion-gels[2-3],which consist of ionic liquids and polymers,sandwiching with two carbon material sheets as shown in Fig.1.This electrol... 相似文献
15.
16.
17.
ARTC1-mediated ADP-ribosylation of GRP78/BiP: a new player in endoplasmic-reticulum stress responses
18.
Elisabetta Meacci Francesca Bini Chiara Sassoli Maria Martinesi Roberta Squecco Flaminia Chellini Sandra Zecchi-Orlandini Fabio Francini Lucia Formigli 《Cellular and molecular life sciences : CMLS》2010,67(24):4269-4285
We recently demonstrated that skeletal muscle differentiation induced by sphingosine 1-phosphate (S1P) requires gap junctions
and transient receptor potential canonical 1 (TRPC1) channels. Here, we searched for the signaling pathway linking the channel
activity with Cx43 expression/function, investigating the involvement of the Ca2+-sensitive protease, m-calpain, and its targets in S1P-induced C2C12 myoblast differentiation. Gene silencing and pharmacological inhibition of
TRPC1 significantly reduced Cx43 up-regulation and Cx43/cytoskeletal interaction elicited by S1P. TRPC1-dependent functions
were also required for the transient increase of m-calpain activity/expression and the subsequent decrease of PKCα levels. Remarkably, Cx43 expression in S1P-treated myoblasts
was reduced by m-calpain-siRNA and enhanced by pharmacological inhibition of classical PKCs, stressing the relevance for calpain/PKCα axis
in Cx43 protein remodeling. The contribution of this pathway in myogenesis was also investigated. In conclusion, these findings
provide novel mechanisms by which S1P regulates myoblast differentiation and offer interesting therapeutic options to improve
skeletal muscle regeneration. 相似文献
19.
Hüffmeier U Uebe S Ekici AB Bowes J Giardina E Korendowych E Juneblad K Apel M McManus R Ho P Bruce IN Ryan AW Behrens F Lascorz J Böhm B Traupe H Lohmann J Gieger C Wichmann HE Herold C Steffens M Klareskog L Wienker TF Fitzgerald O Alenius GM McHugh NJ Novelli G Burkhardt H Barton A Reis A 《Nature genetics》2010,42(11):996-999
Psoriatic arthritis (PsA) is an inflammatory joint disease that is distinct from other chronic arthritides and which is frequently accompanied by psoriasis vulgaris (PsV) and seronegativity for rheumatoid factor. We conducted a genome-wide association study in 609 German individuals with PsA (cases) and 990 controls with replication in 6 European cohorts including a total of 5,488 individuals. We replicated PsA associations at HLA-C and IL12B and identified a new association at TRAF3IP2 (rs13190932, P = 8.56 × 10?1?). TRAF3IP2 was also associated with PsV in a German cohort including 2,040 individuals (rs13190932, P = 1.95 × 10?3). Sequencing of the exons of TRAF3IP2 identified a coding variant (p.Asp10Asn, rs33980500) as the most significantly associated SNP (P = 1.13 × 10?2?, odds ratio = 1.95). Functional assays showed reduced binding of this TRAF3IP2 variant to TRAF6, suggesting altered modulation of immunoregulatory signals through altered TRAF interactions as a new and shared pathway for PsA and PsV. 相似文献
20.
Lu W Schneider M Neumann S Jaeger VM Taranum S Munck M Cartwright S Richardson C Carthew J Noh K Goldberg M Noegel AA Karakesisoglou I 《Cellular and molecular life sciences : CMLS》2012,69(20):3493-3509
Nesprins-1/-2/-3/-4 are nuclear envelope proteins, which connect nuclei to the cytoskeleton. The largest nesprin-1/-2 isoforms (termed giant) tether F-actin through their N-terminal actin binding domain (ABD). Nesprin-3, however, lacks an ABD and associates instead to plectin, which binds intermediate filaments. Nesprins are integrated into the outer nuclear membrane via their C-terminal KASH-domain. Here, we show that nesprin-1/-2 ABDs physically and functionally interact with nesprin-3. Thus, both ends of nesprin-1/-2 giant are integrated at the nuclear surface: via the C-terminal KASH-domain and the N-terminal ABD-nesprin-3 association. Interestingly, nesprin-2 ABD or KASH-domain overexpression leads to increased nuclear areas. Conversely, nesprin-2 mini (contains the ABD and KASH-domain but lacks the massive nesprin-2 giant rod segment) expression yields smaller nuclei. Nuclear shrinkage is further enhanced upon nesprin-3 co-expression or microfilament depolymerization. Our findings suggest that multivariate intermolecular nesprin interactions with the cytoskeleton form a lattice-like filamentous network covering the outer nuclear membrane, which determines nuclear size. 相似文献