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81.
DNA and origin region segregation are not affected by the transition from rod to sphere after inhibition of Escherichia coli MreB by A22 总被引:1,自引:1,他引:0
Karczmarek A Martínez-Arteaga R Baselga RM Alexeeva S Hansen FG Vicente M Nanninga N den Blaauwen T 《Molecular microbiology》2007,65(1):51-63
The bacterial actin homologue MreB forms a helix underneath the cytoplasmic membrane and was shown to be essential in the morphogenesis of the rod-shaped cells. Additionally, MreB was implicated to be involved in DNA segregation. However, in our hands the mreBCD deletion strain (PA340-678) grew without apparent DNA segregation defect, suggesting that the reported chromosome segregation inhibition could be caused by a temporarily effect of MreB inhibition or depletion. To assess the involvement of MreB in DNA segregation during the transition from rod to sphere, we compared the effect of A22 and the PBP2 inhibitor mecillinam on the percentage of cells with segregated nucleoids and the number of oriC foci in wild-type Escherichia coli cells. Cells became spherical in the same time window during both treatments and we could not detect any difference in the chromosome or oriC segregation between these two treatments. Additionally, flow cytometric analyses showed that A22 and mecillinam treatment gave essentially the same chromosome segregation pattern. We conclude that MreB is not directly involved in DNA segregation of E. coli. 相似文献
82.
Could the tree diversity pattern in Europe be generated by postglacial dispersal limitation? 总被引:3,自引:0,他引:3
The relative importance of contemporary climate and history as controls of geographical diversity patterns is intensely debated. A key example is the controversy over the extent to which temperate tree distributions and diversity patterns reflect postglacial dispersal limitation. Here, we focus on Central and Northern Europe, and show that recent estimates of tree migration rates < 100 m year−1 imply that many species have probably not reached equilibrium with climate in this region. We then demonstrate that geographical accessibility from glacial refuges explains 78% of the geographical variation in the region's tree diversity and is a much stronger diversity predictor than climate. Finally, we show that realistic estimates of migration rates can be derived from the observed tree diversity pattern by assuming it to be purely dispersal driven. In conclusion, the tree diversity pattern in Central and Northern Europe could, to a large extent, be a result of postglacial dispersal limitation. 相似文献
83.
Integrative analysis for finding genes and networks involved in diabetes and other complex diseases 下载免费PDF全文
Bergholdt R Størling ZM Lage K Karlberg EO Olason PI Aalund M Nerup J Brunak S Workman CT Pociot F 《Genome biology》2007,8(11):R253
We have developed an integrative analysis method combining genetic interactions, identified using type 1 diabetes genome scan data, and a high-confidence human protein interaction network. Resulting networks were ranked by the significance of the enrichment of proteins from interacting regions. We identified a number of new protein network modules and novel candidate genes/proteins for type 1 diabetes. We propose this type of integrative analysis as a general method for the elucidation of genes and networks involved in diabetes and other complex diseases. 相似文献
84.
Molecular basis for the functional interaction of dynein light chain with the nuclear-pore complex 总被引:1,自引:0,他引:1
Stelter P Kunze R Flemming D Höpfner D Diepholz M Philippsen P Böttcher B Hurt E 《Nature cell biology》2007,9(7):788-796
Nucleocytoplasmic transport occurs through nuclear pore complexes (NPCs) embedded in the nuclear envelope. Here, we discovered an unexpected role for yeast dynein light chain (Dyn2) in the NPC. Dyn2 is a previously undescribed nucleoporin that functions as molecular glue to dimerize and stabilize the Nup82-Nsp1-Nup159 complex, a module of the cytoplasmic pore filaments. Biochemical analyses showed that Dyn2 binds to a linear motif (termed DID(Nup159)) inserted between the Phe-Gly repeat and coiled-coil domain of Nup159. Electron microscopy revealed that the reconstituted Dyn2-DID(Nup159) complex forms a rigid rod-like structure, in which five Dyn2 homodimers align like 'pearls on a string' between two extented DID(Nup159) strands. These findings imply that the rigid 20 nm long Dyn2-DID(Nup159) filament projects the Nup159 Phe-Gly repeats from the Nup82 module. Thus, it is possible that dynein light chain plays a role in organizing natively unfolded Phe-Gly repeats within the NPC scaffold to facilitate nucleocytoplasmic transport. 相似文献
85.
Carol Saunders Laurie Smith Flemming Wibrand Kirstine Ravn Peter Bross Isabelle Thiffault Mette Christensen Andrea Atherton Emily Farrow Neil Miller Stephen?F. Kingsmore Elsebet Ostergaard 《American journal of human genetics》2015,96(2):258-265
3-methylglutaconic aciduria (3-MGA-uria) is a nonspecific finding associated with mitochondrial dysfunction, including defects of oxidative phosphorylation. 3-MGA-uria is classified into five groups, of which one, type IV, is genetically heterogeneous. Here we report five children with a form of type IV 3-MGA-uria characterized by cataracts, severe psychomotor regression during febrile episodes, epilepsy, neutropenia with frequent infections, and death in early childhood. Four of the individuals were of Greenlandic descent, and one was North American, of Northern European and Asian descent. Through a combination of homozygosity mapping in the Greenlandic individuals and exome sequencing in the North American, we identified biallelic variants in the caseinolytic peptidase B homolog (CLPB). The causative variants included one missense variant, c.803C>T (p.Thr268Met), and two nonsense variants, c.961A>T (p.Lys321∗) and c.1249C>T (p.Arg417∗). The level of CLPB protein was markedly decreased in fibroblasts and liver of affected individuals. CLPB is proposed to function as a mitochondrial chaperone involved in disaggregation of misfolded proteins, resulting from stress such as heat denaturation. 相似文献
86.
87.
Na(+),K(+)-adenosine triphosphatase (NKA) is the first P-type ion translocating adenosine triphosphatase (ATPase) ever identified, and the significance of this class of proteins was highlighted by the 1997 Nobel Prize in Chemistry awarded to Jens C. Skou for the discovery in 1957. More than half a century passed between the initial identification and the publication of a high-resolution crystal structure of NKA. Although the new crystal structures provided many surprises and insights, structural biology on this system remains challenging, as NKA is a very difficult protein to crystallize. Here we explain the reasons behind the challenges, introduce a mechanism that governs the function, and summarize current knowledge of NKA structure in comparison with another member of the P-type ATPase family, Ca(2+)-ATPase. 相似文献
88.
89.
Jes Jessen Rasmussen Annette Baattrup-Pedersen Tenna Riis Nikolai Friberg 《Aquatic Ecology》2011,45(2):231-242
We surveyed macrophyte community structure and measured community metabolism and nutrient uptake along a temperature gradient
(9.7–17.4°C) in four Icelandic streams influenced by geothermal heating. The study streams are part of the geothermal area
in Hengill that is uniquely characterised by streams with comparable water chemistry despite the geothermal influence. Stream
metabolism was studied applying the diurnal upstream–downstream dissolved oxygen change technique. Nutrient uptake was studied
by adding solutions of nitrogen and phosphorus together with a conservative tracer. Rates of primary production (GPP) and
uptake of nitrate–N and phosphate-P increased with increasing stream temperature. GPP was 20 times higher (up to 12.99 g O2 m−2 day−1) and rates of nutrient uptake were up to 30-times higher (up to 22.99, 13.31 and 7.94 mg m−2 h−1 for ammonium, nitrate and phosphate, respectively) in the warmest streams compared with the coldest. Furthermore, macrophytes,
when present, were strongly controlling ecosystem processes. Our study implies that temperature may affect stream ecosystem
processes both directly (i.e. physiologically) and indirectly (i.e. by changing other structural parameters). 相似文献
90.