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931.
932.
Xiaojuan Sun Hui He Zhihui Xie Weiping Qian Haiyen E. Zhau Leland W. K. Chung Fray F. Marshall Ruoxiang Wang 《In vitro cellular & developmental biology. Animal》2010,46(6):538-546
Prostate stromal cells may play binary roles in the process of prostate cancer development. As the first to be encountered
by infiltrating prostate cancer cells, prostate stromal cells form the first defense line against prostate cancer progression
and metastasis. However, interaction between prostate cancer and stromal cells may facilitate the formation of a tumor microenvironment
favoring cancer cell growth and survival. To establish an experimental system for studying the interaction between cancer
and stromal cells, we isolated three matched pairs of normal and cancer-associated human prostate stromal clones. In this
report, we describe the morphologic and behavioral characteristics of these cells and their effect on LNCaP prostate cancer
cells in co-culture. Unlike LNCaP prostate cancer cells, the isolated prostate stromal clones are large fibroblast-like cells
with a slow proliferation rate. Growth and survival of these clones are not affected by androgens. The stromal cells display
high resistance to serum starvation, while cancer-associated stromal clones have differentiated survival ability. In co-culture
experiments, the stromal cells protected some LNCaP prostate cancer cells from death by serum starvation, and cancer-associated
stromal clones showed more protection. This work thus established a panel of valuable human prostate stromal cell lines, which
could be used in co-culture to study the interaction between prostate cancer and prostate stromal cells. 相似文献
933.
Chris Smillie M. Pilar Garcill��n-Barcia M. Victoria Francia Eduardo P. C. Rocha Fernando de la Cruz 《Microbiology and molecular biology reviews》2010,74(3):434-452
Summary: Plasmids are key vectors of horizontal gene transfer and essential genetic engineering tools. They code for genes involved in many aspects of microbial biology, including detoxication, virulence, ecological interactions, and antibiotic resistance. While many studies have decorticated the mechanisms of mobility in model plasmids, the identification and characterization of plasmid mobility from genome data are unexplored. By reviewing the available data and literature, we established a computational protocol to identify and classify conjugation and mobilization genetic modules in 1,730 plasmids. This allowed the accurate classification of proteobacterial conjugative or mobilizable systems in a combination of four mating pair formation and six relaxase families. The available evidence suggests that half of the plasmids are nonmobilizable and that half of the remaining plasmids are conjugative. Some conjugative systems are much more abundant than others and preferably associated with some clades or plasmid sizes. Most very large plasmids are nonmobilizable, with evidence of ongoing domestication into secondary chromosomes. The evolution of conjugation elements shows ancient divergence between mobility systems, with relaxases and type IV coupling proteins (T4CPs) often following separate paths from type IV secretion systems. Phylogenetic patterns of mobility proteins are consistent with the phylogeny of the host prokaryotes, suggesting that plasmid mobility is in general circumscribed within large clades. Our survey suggests the existence of unsuspected new relaxases in archaea and new conjugation systems in cyanobacteria and actinobacteria. Few genes, e.g., T4CPs, relaxases, and VirB4, are at the core of plasmid conjugation, and together with accessory genes, they have evolved into specific systems adapted to specific physiological and ecological contexts. 相似文献
934.
935.
Leanna M. Birge Andrea L. Hughes Jeremy L. Marshall Daniel J. Howard 《Journal of Insect Behavior》2010,23(4):268-289
Close range prezygotic barriers are assumed to be present between sister taxa who have overlapping distributions. Here we
report the results of studies designed to test the existence of prezygotic barriers between two closely related species, A. fasciatus and A. socius. We finely dissected the courtship and mating rituals and performed Monte Carlo analysis on lengths of time and number of
occurrences of particular events in the courtship mating sequence. These detailed investigations of the courtship and mating
behavior of conspecific and heterospecific pairs demonstrate that behavioral isolation is non-existent. We also measure the
adult lifespan and number of progeny produced from singly and multiply mated males and females in conspecific and heterospecific
trials. We found that cost of a heterospecific mating is asymmetric between the sexes with males paying a higher cost. 相似文献
936.
937.
C. Ellery Mayence David J. Marshall Robert C. Godfree 《Wetlands Ecology and Management》2010,18(6):717-730
Wetlands are prone to increased invasion by plant species following changes in hydrologic regime, leading to shifts in plant
community composition and potentially ecosystem function and health. In this paper, the ecology and potential control of Juncus ingens, a native wetland plant in the Murray-Darling Basin of south-eastern Australia, is investigated. J. ingens has benefited from altered Murray River hydrologic conditions by expanding its range and invading seasonally-flooded grassland
and riparian habitats along the Murray River. Here results of complementary glasshouse and field research of seedling and
mature J. ingens growth and resilience as influenced by hydrologic regime (moist, saturated, partial inundation and when possible, complete
inundation) and mechanical control (i.e., clipping) are presented. A moist hydrologic regime (soil held at field capacity)
resulted in the most vigorous seedlings (13.9–73.0% more total biomass), while saturated conditions (flooding maintained level
with the soil surface) resulted in the most vigorous mature J. ingens (14.1–98.4% more total biomass). Seedling mortality was greatest under complete and prolonged inundation (60% fatal with
remaining 40% showing severe stress), conditions suspected to have limited prior invasion but which currently occur infrequently
as a result of reduced flooding magnitude. Clipping was fatal for nearly all seedlings regardless of hydrologic regime but
was only fatal for mature plants if coupled with prolonged inundation. Coupling ground-level clipping with strategic flooding
may be the most effective means for controlling current populations of J. ingens and limiting further invasion, promoting re-colonisation by displaced species and rehabilitating the health of Barmah Forest
and similar Murray River floodplain wetlands. 相似文献
938.
Diane L. Marshall Anna P. Tyler Nathan J. Abrahamson Joy J. Avritt Melanie G. Barnes Leah L. Larkin Juliana S. Medeiros Jerusha Reynolds Marieken G. M. Shaner Heather L. Simpson Satya Maliakal-Witt 《Sexual plant reproduction》2010,23(4):325-336
Although increases in atmospheric [CO2] are known to affect plant physiology, growth and reproduction, understanding of these effects is limited because most studies of reproductive consequences focus solely on female function. Therefore, we examined the effects of CO2 enrichment on male function in the annual Raphanus sativus. Pollen donors grown under elevated [CO2] initially sired a higher proportion of seeds per fruit than ambient [CO2]-grown plants when each was tested against two different standard competitors; however, by the end of the 5-month experiment, these pollen donors sired fewer seeds than ambient [CO2]-grown plants and produced a lower proportion of viable pollen grains. The results of this experiment confirm that elevated [CO2] can alter reproductive success. Additionally, the change in response to elevated [CO2] over time varied among pollen donor families; thus, changes in [CO2] could act as a selective force on this species. 相似文献
939.
Deutscher AT Jenkins C Minion FC Seymour LM Padula MP Dixon NE Walker MJ Djordjevic SP 《Molecular microbiology》2010,78(2):444-458
Bacteriophage T4 is decorated with 155 copies of the highly antigenic outer capsid protein, Hoc. The Hoc molecule (40 kDa) is present at the centre of each hexameric capsomer and provides a good platform for surface display of pathogen antigens. Biochemical and modelling studies show that Hoc consists of a string of four domains, three immunoglobulin (Ig)‐like and one non‐Ig domain at the C‐terminus. Biochemical data suggest that the Hoc protein has two functional modules, a capsid binding module containing domains 1 and 4 and a solvent‐exposed module containing domains 2 and 3. This model is consistent with the dumbbell‐shaped cryo‐EM density of Hoc observed in the reconstruction of the T4 capsid. Mutagenesis localized the capsid binding site to the C‐terminal 25 amino acids, which are predicted to form two β‐strands flanking a capsid binding loop. Mutations in the loop residues, ESRNG, abolished capsid binding, suggesting that these residues might interact with the major capsid protein, gp23*. With the conserved capsid binding module forming a foothold on the virus and the solvent‐exposed module able to adapt to bind to a variety of surfaces, Hoc probably provides survival advantages to the phage, such as increasing the virus concentration near the host, efficient dispersion of the virus and exposing the tail for more efficient contact with the host cell surface prior to infection. 相似文献
940.
Objectives: Tumour cells respond to ionizing radiation by cycle arrest, cell death or repair and possible regrowth. We have developed a dynamic mathematical model of the cell cycle to incorporate transition probabilities for entry into DNA replication and mitosis. In this study, we used the model to analyse effects of radiation on cultures of five human melanoma cell lines. Materials and methods: Cell lines were irradiated (9 Gy) prior to further culture and harvesting at multiple points up to 96 h later. Cells were fixed, stained with propidium iodide and analysed for G1‐, S‐ and G2/M‐phase cells by flow cytometry. Data for all time points were fitted to a mathematical model. To provide unique solutions, cultures were grown in the presence and absence of the mitotic poison paclitaxel, added to prevent cell division. Results: The model demonstrated that irradiation at 9 Gy induced G2‐phase arrest in all lines for at least 96 h. Two cell lines with wild‐type p53 status additionally exhibited G1‐phase arrest with recovery over 15 h, as well as evidence of cell loss. Resumption of cycling of surviving cells, as indicated by increases in G1/S and G2/M‐phase transitions, was broadly comparable with results of clonogenic assays. Conclusions: The results, combined with existing data from clonogenic survival assays, support the hypothesis that a dominant effect of radiation in these melanoma lines is the induction of long‐term cell cycle arrest. 相似文献