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81.
Fangyu Cheng Qianying Gong Huimin Yu Gregory Stephanopoulos 《Biotechnology journal》2016,11(4):574-584
Hyaluronic acid (HA) plays important roles in human tissue system, thus it is highly desirable for various applications, such as in medical, clinic and cosmetic fields. The wild microbial producer of HA, streptococcus, was restricted by its potential pathogens, hence different recombinant hosts are being explored. In this work, we engineered Corynebacterium glutamicum, a GRAS (Generally Recognized as Safe) organism free of exotoxins and endotoxins to produce HA with high titer and satisfied Mw. The ssehasA gene encoding hyaluronan synthase (HasA) was artificially synthesized with codon preference of C. glutamicum. Other genes involved in the HA synthetic pathway were directly cloned from the C. glutamicum genome. The operon structures and constitutive or inducible promoters were particularly compared and the preferred environmental conditions were also optimized. Using glucose and corn syrup powder as carbon and nitrogen sources, batch cultures of the engineered C.glutamicum with operon ssehasA‐hasB driven by Ptac promoter were performed in a 5 L fermentor. The maximal HA titer, productivity and yield reached 8.3 g/L, 0.24 g/L/h and 0.22 gHA/gGlucose, respectively; meanwhile the maximal Mw was 1.30 MDa. This work provides a safe and efficient novel producer of HA with huge industrial prospects. 相似文献
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84.
David A. Turner Peter Baillie‐Johnson Alfonso Martinez Arias 《BioEssays : news and reviews in molecular, cellular and developmental biology》2016,38(2):181-191
Understanding the mechanisms of early embryonic patterning and the timely allocation of specific cells to embryonic regions and fates as well as their development into tissues and organs, is a fundamental problem in Developmental Biology. The classical explanation for this process had been built around the notion of positional information. Accordingly the programmed appearance of sources of Morphogens at localized positions within a field of cells directs their differentiation. Recently, the development of organs and tissues from unpatterned and initially identical stem cells (adult and embryonic) has challenged the need for positional information and even the integrity of the embryo, for pattern formation. Here we review the emerging area of organoid biology from the perspective of Developmental Biology. We argue that the events underlying the development of these systems are not purely linked to “self‐organization,” as often suggested, but rather to a process of genetically encoded self‐assembly where genetic programs encode and control the emergence of biological structures. 相似文献
85.
Jelena Petrovic Yeqiao Zhou Maria Fasolino Naomi Goldman Gregory W. Schwartz Maxwell R. Mumbach Son C. Nguyen Kelly S. Rome Yogev Sela Zachary Zapataro Stephen C. Blacklow Michael J. Kruhlak Junwei Shi Jon C. Aster Eric F. Joyce Shawn C. Little Golnaz Vahedi Warren S. Pear Robert B. Faryabi 《Molecular cell》2019,73(6):1174-1190.e12
86.
Zekun Huang Wanlong Huang Xiaolin Liu Zhaofang Han Guangjian Liu Grace Afumwaa Boamah Yi Wang Feng Yu Yang Gan Qizhen Xiao Xuan Luo Nan Chen Meng Liu Weiwei You Caihuan Ke 《Molecular ecology resources》2022,22(1):15-27
The nautilus, commonly known as a “living fossil,” is endangered and may be at risk of extinction. The lack of genomic information hinders a thorough understanding of its biology and evolution, which can shed light on the conservation of this endangered species. Here, we report the first high-quality chromosome-level genome assembly of Nautilus pompilius. The assembled genome size comprised 785.15 Mb. Comparative genomic analyses indicated that transposable elements (TEs) and large-scale genome reorganizations may have driven lineage-specific evolution in the cephalopods. Remarkably, evolving conserved genes and recent TE insertion activities were identified in N. pompilius, and we speculate that these findings reflect the strong adaptability and long-term survival of the nautilus. We also identified gene families that are potentially responsible for specific adaptation and evolution events. Our study provides unprecedented insights into the specialized biology and evolution of N. pompilius, and the results serve as an important resource for future conservation genomics of the nautilus and closely related species. 相似文献
87.
We report on the dynamics of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-lissamine rhodamine B sulfonyl ammonium salt (Rhodamine-PE), incorporated into unilamellar vesicles composed of 1,2-dimyristoyl-sn-phosphatidylcholine (DMPC). A key question in the investigation of any bilayer system using tethered fluorescent probes is the role that the chromophore itself plays in determining the organization of phospholipid bilayers. In this work, we investigate the role of headgroup-bound chromophores by measuring the steady state and time-resolved fluorescence response of the tethered rhodamine chromophore as a function of concentration in the bilayer. We find that both the steady state and dynamical properties of the chromophores change with concentration, in a manner consistent with the introduction of disorganization to the bilayers. Steady state fluorescence spectra show a clear perturbation of the rhodamine emission spectrum at a chromophore concentration of 0.25 mol%, which is not seen for lower concentrations, and fluorescence anisotropy data show that both the motional freedom and confining volume experienced by the chromophore increase with concentration. Taken collectively, our data point to the importance of using low concentrations of optical probes in the interrogation of bilayer structures. 相似文献
88.
T. N. C. Vidya Surendra Varma Nguyen X. Dang T. Van Thanh R. Sukumar 《Conservation Genetics》2007,8(6):1471-1478
Vietnam’s elephant population that has suffered severe declines during the past three decades is now believed to number 60–80
individuals in the wild. Cat Tien National Park is thought to be one of the key areas for the recovery of Vietnam’s elephants.
We carried out a molecular genetic study of elephants in Cat Tien National Park and its adjoining areas with the objectives
of estimating minimum population size, assessing genetic diversity, and obtaining insights into social organization. We obtained
a minimum population size of 11 elephants based on a combination of unique nuclear microsatellite genotypes and mitochondrial
haplotypes. While mitochondrial diversity based on a 600-base pair segment was high in this small sample of individuals, the
six microsatellite loci examined showed low diversity and the signature of a recent population bottleneck. Along with nuclear
genetic depauperation of Cat Tien’s elephants, we also report disruption of normal social organization, with different matrilines
having coalesced into a single social group because of anthropogenic disturbance. The results emphasize the critical condition
of this elephant population and the need for urgent conservation measures if this population is to be saved. 相似文献
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90.
Flip‐flop organization in the chloroplast genome of Capsosiphon fulvescens (Ulvophyceae,Chlorophyta)
Dongseok Kim JunMo Lee Ji Won Choi Ji Hyun Yang Il‐Ki Hwang Hwan Su Yoon 《Journal of phycology》2019,55(1):214-223
To better understand organelle genome evolution of the ulvophycean green alga Capsosiphon fulvescens, we sequenced and characterized its complete chloroplast genome. The circular chloroplast genome was 111,561 bp in length with 31.3% GC content that contained 108 genes including 77 protein‐coding genes, two copies of rRNA operons, and 27 tRNAs. In this analysis, we found the two types of isoform, called heteroplasmy, were likely caused by a flip‐flop organization. The flip‐flop mechanism may have caused structural variation and gene conversion in the chloroplast genome of C. fulvescens. In a phylogenetic analysis based on all available ulvophycean chloroplast genome data, including a new C. fulvescens genome, we found three major conflicting signals for C. fulvescens and its sister taxon Pseudoneochloris marina within 70 individual genes: (i) monophyly with Ulotrichales, (ii) monophyly with Ulvales, and (iii) monophyly with the clade of Ulotrichales and Ulvales. Although the 70‐gene concatenated phylogeny supported monophyly with Ulvales for both species, these complex phylogenetic signals of individual genes need further investigations using a data‐rich approach (i.e., organelle genome data) from broader taxon sampling. 相似文献