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101.
102.
Developmental anomalies of central respiratory neural control contribute to newborn mortality and morbidity. Elucidation of the cellular, molecular, trophic, and genetic mechanisms involved in the formation and function of respiratory nuclei during prenatal development will provide a foundation for understanding pathologies. The pre-B?tzinger Complex (pre-B?tC) is a specific group of neurons located in the ventrolateral medulla that is critical for respiratory rhythmogenesis. Thus it has become a major focus of research. Here, we provide an overview of current knowledge regarding the anatomical and functional emergence of the rodent pre-B?tC during the prenatal period. 相似文献
103.
Shimada M Greer PA McMahon AP Bouxsein ML Schipani E 《The Journal of biological chemistry》2008,283(30):21002-21010
Calpains are intracellular cysteine proteases, which include widely expressed mu- and m-calpains (1). Both mu-calpains and m-calpains are heterodimers consisting of a large catalytic subunit and a small regulatory subunit. The calpain small subunit encoded by the gene Capn4 directly binds to the intracellular C-terminal tail (C-tail) of the receptor for parathyroid hormone and parathyroid hormone-related peptide and modulates its cellular functions in osteoblasts in vitro (2). To investigate a potential role of the calpain small subunit in osteoblasts in vivo, we generated osteoblast-specific Capn4 knock-out mice using the Cre-LoxP system (3). Mutant mice had smaller bodies with shorter limbs, reduced trabecular bone with thinner cortices, and decreased osteoblast number. In vitro analysis confirmed that deletion of Capn4 in osteoblasts severely affected multiple osteoblast functions including proliferation, differentiation, and matrix mineralization. Collectively, our findings provide the first in vivo demonstration that the calpain small subunit is essential for proper osteoblast activity and bone remodeling. 相似文献
104.
105.
Selection of Specific Endophytic Bacterial Genotypes by Plants in Response to Soil Contamination 总被引:10,自引:2,他引:8
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Steven D. Siciliano Nathalie Fortin Anca Mihoc Gesine Wisse Suzanne Labelle Danielle Beaumier Danielle Ouellette Real Roy Lyle G. Whyte M. Kathy Banks Paul Schwab Ken Lee Charles W. Greer 《Applied microbiology》2001,67(6):2469-2475
Plant-bacterial combinations can increase contaminant degradation in the rhizosphere, but the role played by indigenous root-associated bacteria during plant growth in contaminated soils is unclear. The purpose of this study was to determine if plants had the ability to selectively enhance the prevalence of endophytes containing pollutant catabolic genes in unrelated environments contaminated with different pollutants. At petroleum hydrocarbon contaminated sites, two genes encoding hydrocarbon degradation, alkane monooxygenase (alkB) and naphthalene dioxygenase (ndoB), were two and four times more prevalent in bacteria extracted from the root interior (endophytic) than from the bulk soil and sediment, respectively. In field sites contaminated with nitroaromatics, two genes encoding nitrotoluene degradation, 2-nitrotoluene reductase (ntdAa) and nitrotoluene monooxygenase (ntnM), were 7 to 14 times more prevalent in endophytic bacteria. The addition of petroleum to sediment doubled the prevalence of ndoB-positive endophytes in Scirpus pungens, indicating that the numbers of endophytes containing catabolic genotypes were dependent on the presence and concentration of contaminants. Similarly, the numbers of alkB- or ndoB-positive endophytes in Festuca arundinacea were correlated with the concentration of creosote in the soil but not with the numbers of alkB- or ndoB-positive bacteria in the bulk soil. Our results indicate that the enrichment of catabolic genotypes in the root interior is both plant and contaminant dependent. 相似文献
106.
John Westbrook Zukang Feng Shri Jain T. N. Bhat Narmada Thanki Veerasamy Ravichandran Gary L. Gilliland Wolfgang F. Bluhm Helge Weissig Douglas S. Greer Philip E. Bourne Helen M. Berman 《Nucleic acids research》2002,30(1):245-248
The Protein Data Bank (PDB; http://www.pdb.org/) is the single worldwide archive of structural data of biological macromolecules. This paper describes the progress that has been made in validating all data in the PDB archive and in releasing a uniform archive for the community. We have now produced a collection of mmCIF data files for the PDB archive (ftp://beta.rcsb.org/pub/pdb/uniformity/data/mmCIF/). A utility application that converts the mmCIF data files to the PDB format (called CIFTr) has also been released to provide support for existing software. 相似文献
107.
Ping Gong Steven D. Siciliano Sonali Srivastava Charles W. Greer Geoffrey I. Sunahara 《人类与生态风险评估》2002,8(5):1067-1081
This study attempted to investigate if the tolerance of soil bacterial communities in general, and autotrophic ammonia-oxidizing bacteria (AOB) in particular, evolved as a result of prolonged exposure to metals, and could be used as an indigenous bioindicator for soil metal pollution. A soil contaminated with copper, chromium, and arsenic (CCA) was mixed with an uncontaminated garden soil (GS3) to make five test soils with different metal concentrations. A modified potential ammonium oxidation assay was used to determine the metal tolerance of the AOB community. Tolerance to Cr, Cu, and As was tested at the beginning and after up to 13 months of incubation. Compared with the reference GS3 soil, the five CCA soils showed significantly higher tolerance to Cr no matter which form of Cr (Cr3+, CrO4 2?, or Cr2O7 2?) was tested, and the Cr tolerance correlated with the total soil Cr concentration. However, the tolerance to Cu2+, As3+, and As5+ did not differ significantly between the GS3 soil and the five CCA soils. Community level physiological profiles using Biolog microtiter plates were also used to examine the chromate tolerance of the bacterial communities extracted after six months of exposure. Our results showed that the bacterial community tolerance was altered and increased as the soil Cr concentration was increased, indicating that the culturable microbial community and the AOB community responded in a similar manner. 相似文献
108.
Cdk5 on the brain. 总被引:7,自引:0,他引:7
Mammalian brains are highly compartmentalized into groups of functionally specialized neurons. Cell migration and neurite outgrowth must be tightly orchestrated to achieve this level of organization. A small serine/threonine kinase that shows homology to cyclin-dependent kinases (Cdks) has emerged as an important regulator of neuronal migration. Cdk5, unlike other Cdks, is not regulated by cyclins, and its activity is primarily detected in postmitotic neurons in developing and adult nervous systems. This review describes work indicating that Cdk5 links extracellular signaling pathways and cytoskeletal/membrane systems to direct neuronal migration, axon growth, and possibly neurosecretion. Despite its importance, unchecked Cdk5 activity is toxic to neurons, and may underlie some of the pathologies associated with neurodegenerative disorders such as Alzheimer's disease and amyotrophic lateral sclerosis. 相似文献
109.
110.
The influence of moisture on the survival, movement anddegradation activity of a 2,4-D degrading bacterium,Burkholderia cepacia strain BRI6001L, geneticallyengineered to contain bioluminescent and lactoseutilization genes, was studied in unsaturated soil columns.The distance traveled by BRI6001L was dependent on theclay content of the soil, higher clay contents beingresponsible for higher filtration coefficients. Long termsurvival, in excess of one year, was attributed to strainBRI6001L's ability to survive dry conditions. Changes inthe 2,4-D biodegradation rate showed a better correlationwith the BRI6001L population density than with the totalviable bacterial population. At moisture levels betweenfield capacity and 40% moisture (– 33 kPa to –100 kPa)2,4-D degradation was attributed mainly to BRI6001L. Atmoisture levels between 6 and 15%, 2,4-D disappearancewas attributed to the indigenous microbial population,with no degradation occurring at moisture levels below6%. Returning the moisture to above 40% led to anincrease of 4 orders of magnitude in the BRI6001Lpopulation density and to a 10-fold increase in the 2,4-Ddegradation rate. The ability to monitor a specificmicrobial population using reporter genes hasdemonstrated the importance of controlling moisturelevels for maximizing biodegradation rates in unsaturatedsoil environments. 相似文献