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461.
Molecular Cloning of the Tryptophan Operon from an Aeromonas hydrophila Freshwater Isolate 总被引:1,自引:1,他引:0
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A genomic library of Aeromonas hydrophila F9 was constructed by using pBR322 as a vector. From that, two DNA fragments (5.8 and 11.6 kb) were isolated containing genetic information to complement trpA and trpB defects (5.8-kb fragment) and to complement trpA, trpB, trpC, trpD, and trpE defects (11.6-kb fragment) in Escherichia coli mutants. Evidence of the existence of a secondary promoter is given. 相似文献
462.
D Navarro J J Cabrera O Falcón P Jiménez A Ruiz R Chirino A López J F Rivero J C Díaz-Chico B N Díaz-Chico 《Journal of steroid biochemistry》1989,34(1-6):491-498
Uterine leiomyoma occurs in one of every four or five women during their reproductive life. Its origin is unknown but it is accepted that estrogens play a significant role in its development. In order to learn more about the estrogen dependency of leiomyoma, the biochemical and immunological properties of two markers of estrogen response in target cells (the progesterone receptor (PR) and the stress-responsive protein of 27 kDa (SRP27)) were studied in leiomyoma. The ER (estrogen receptor) and PR content were determined by conventional DCC exchange assays. Specific anti-ER, anti-PR and anti-SRP27 monoclonal antibodies were used in immunoblots and immunohistochemical (IHC) studies. The binding properties of PR from cytosol of leiomyoma showed a Kd of 0.8-1.3 nM, which is in the range described for other human tissues. 80% of all studied leiomyoma contained PR, in a range of 805-2000 fmol/mg protein. The Kd for leiomyoma ER was 0.1-0.9 nM, and 84% of the samples were positive for ER. The PR of leiomyoma has the two A and B forms of 120 and 94 kDa, as shown in the immunoblot using the AB52 anti-PR monoclonal antibody. The IHC study revealed that the PR is concentrated in the cell nuclei, in the form of perinuclear bodies, with a homogeneous staining pattern from cell to cell. The leiomyoma fibres contain SRP27 in a higher concentration than the healthy myometrium. The leiomyoma SRP27 shows a typical doublet of 24 kDa and 27 kDa in immunoblot, the same as in MCF-7 cells. The IHC study revealed a high degree of organization of SRP27 in leiomyoma cells, suggesting that this protein may be part of the cytoskeleton. The results obtained show that human leiomyomas contain ER, PR and RSP27 with similar immunological and biochemical properties to those of other human tissues, including the MCF-7 breast cancer cell line. 相似文献
463.
José-Luis L Rivero Antonio Ruz Silvia Martí-Korff José-Carlos Estepa Escolástico Aguilera-Tejero Jutta Werkman Mathias Sobotta Arno Lindner 《Journal of applied physiology》2007,102(5):1871-1882
This study examined the effects of the intensity and duration of exercise on the nature and magnitude of training adaptations in muscle of adolescent (2-3 yr old) racehorses. Six thoroughbreds that had been pretrained for 2 mo performed six consecutive conditioning programs of varying lactate-guided intensities [velocities eliciting blood lactate concentrations of 2.5 mmol/l (v2.5) and 4 mmol/l (v4), respectively] and durations (5, 15, 25 min). Pre- and posttraining gluteus muscle biopsies were analyzed for myosin heavy chain content, fiber-type composition, fiber size, capillarization, and fiber histochemical oxidative and glycolytic capabilities. Although training adaptations were similar in nature, they varied greatly in magnitude among the different training protocols. Overall, the use of v4 as the exercise intensity for 25 min elicited the most consistent training adaptations in muscle, whereas the minimal training stimulus that evoked any significant change was identified with exercises of 15 min at v2.5. Within this range, muscular adaptations showed significant trends to be proportional to the exercise load of specific training programs. Taken together, these data suggest that muscular adaptations to training in horses occur on a continuum that is based on the exercise intensity and duration of training. The practical implications of this study are that exercises for 15 to 25 min/day at velocities between v2.5 and v4 can improve in the short term (3 wk) the muscular stamina in thoroughbreds. However, exercises of 5-15 min at v4 are necessary to enhance muscular features related to strength (hypertrophy). 相似文献
464.
Berthold J Schenková K Ramos S Miura Y Furukawa M Aspenström P Rivero F 《Experimental cell research》2008,314(19):3453-3465
RhoBTB proteins are atypical members of the Rho family of small GTPases. Two of the three RhoBTB proteins, RhoBTB1 and RhoBTB2, have been proposed as tumor suppressors and might function as adaptors of Cul3-dependent ubiquitin ligase complexes. Using yeast two-hybrid analysis and co-immunoprecipitation we show that all three RhoBTB proteins interact with Cul3. The interaction requires the N-terminal region of Cul3 and the first BTB domain of RhoBTB. RhoBTB3, the only RhoBTB with a prenylation motif, associates with vesicles that are frequently found in the vicinity of microtubules, suggesting a participation in some aspects of vesicle trafficking. We also show that RhoBTB2 and RhoBTB3 are capable of homo and heterodimerizing through the BTB domain region. The GTPase domain, which does not bind GTP, is able to interact with the BTB domain region, thus preventing proteasomal degradation of RhoBTB. This fits into a model in which an intramolecular interaction maintains RhoBTB in an inactive state, preventing the formation or the functionality of Cul3-dependent complexes. We also report a significantly decreased expression of RHOBTB and CUL3 genes in kidney and breast tumor samples and a very good correlation in the expression changes between RHOBTB and CUL3 that suggests that these genes are subject to a common inactivation mechanism in tumors. 相似文献
465.
Rezával C Berni J Gorostiza EA Werbajh S Fagilde MM Fernández MP Beckwith EJ Aranovich EJ Sabio y García CA Ceriani MF 《PloS one》2008,3(10):e3332
Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenerative mechanisms. One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain. Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant. Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor. Thus, this mutant recapitulates two important features of human neurodegenerative diseases, i.e., vulnerability of certain neuronal populations and progressive degeneration, offering a unique scenario in which to unravel the specific mechanisms in an easily tractable organism. 相似文献
466.
Victor E. Balderas Hernández Luz M. T. Paz Maldonado Emilio Medina Rivero Ana P. Barba de la Rosa Leandro G. Ordoñez Acevedo Antonio De León Rodríguez 《Biotechnology and Bioprocess Engineering》2008,13(1):7-13
The production of human interferon gamma (hIFN-γ) using a synthetic gene in Escherichia coli BL21-SI was optimized by response surface methodology (RSM) and a Box-Behnken design. The process variables studied were
temperature, bio-mass concentration at induction time and the NaCl concentration as inducer. According to the Box-Behnken
design, a second order response function was developed. The optimal expression conditions were a temperature of 32.6°C, induction
biomass of 0.31 g/L and 0.3 M NaCl in minimal medium. The model prediction for the maximum hIFN-γ production was 77.3 mg/L,
which corresponded satisfactorily with the experimental data. The hIFN-γ concentration attained under optimized conditions
was 13-times higher than that obtained using the non-optimized conditions. We conclude that RSM is an effective method for
the optimization of recombinant protein expression using synthetic genes in E. coli. 相似文献
467.
María Vanessa Lencinas Guillermo Martínez Pastur Paola Rivero Carlos Busso 《Biodiversity and Conservation》2008,17(11):2579-2597
Conservation strategies of forested landscapes must consider biodiversity of the included site types, i.e. timber-quality
forests and associated non-timber-quality stands. The objectives were to characterize forest overstory structure in timber-quality
versus associated non-timber-quality stands; and to compare their understory communities. Six forest types were sampled in
Nothofagus forests of Tierra del Fuego (Argentina): two timber-quality N. pumilio forests, and four associated non-timber-quality stands (edge, N. antarctica, wetlands and streamside forests). Overstory structure and understory vegetation (species richness, frequencies, cover and
biomass) were characterized during spring and summer seasons. Analysis of variance and multivariates were carried out. Overstory
structure differed across the site types, with higher tree size, canopy closure and tree volume in timber-quality stands.
Fifty-one understory plant species were observed, but understory variables varied with site types, especially wetlands (highest
native and exotic richness, cover and biomass, and 25% of exclusive species). Site types were grouped in three: N. antarctica stands, streamside stands and the other N. pumilio forests according to multivariate analysis. Forty three percent of plants were distributed in all site types, and all timber-quality
forest understory species were present in some associated non-timber-quality stands. Timber-quality N. pumilio forests have a marginal value for understory conservation compared to associated non-timber-quality stands, because these
last include all the plants observed in timber-quality forests and also possess many exclusive species. Therefore, protection
of associated non-timber-quality stands during forest management planning could increase understory conservation at landscape
level, and these could be better reserves of understory diversity than retentions of timber-quality stands. 相似文献
468.
Blue green algal (cyanobacterial) toxins, surface drinking water, and liver cancer in Florida 总被引:1,自引:0,他引:1
Lora E. Fleming Carlos Rivero John Burns Chris Williams Judy A. Bean Kathleen A. Shea John Stinn 《Harmful algae》2002,1(2):157-168
The blue green algae or cyanobacteria represent a diverse group of organisms that produce potent natural toxins. There have been case reports of severe morbidity and mortality in domestic animals through drinking water contaminated by these toxins. Microcystins, in particular, have been associated with acute liver damage and possibly liver cancer in laboratory animals. Although, there has been little epidemiologic research on toxin effects in humans, a study by Yu (1995) found an association between primary liver cancer and surface water. Surface water drinking supplies are particularly vulnerable to the growth of these organisms; current US drinking water treatment practices do not monitor or actively treat for blue green algal toxins including the microcystins.After a monitoring survey in Florida found organisms and microcystins (among other cyanobacterial toxins) in surface water drinking sources, a pilot ecological study was performed using a Geographic Information System (GIS) to evaluate the risk of primary hepatocellular carcinoma (HCC) and proximity to a surface water treatment plant at cancer diagnosis. The study linked all HCC cancers diagnosed in Florida from 1981 to 1998 with environmental databases.A significantly increased risk for HCC with residence within the service area of a surface water treatment plant was found compared to persons living in areas contiguous to the surface water treatment plants. However, this increased risk was not seen in comparison to persons living in randomly selected ground water treatment service areas or compared to the Florida cumulative incidence rate for the study period, using various comparison and GIS methodologies. Furthermore, these findings must be interpreted in light of significant issues of latency, high population mobility, and the lack of individual exposure information. Nevertheless, the issue of acute and chronic human health effects associated with the consumption of surface waters possibly contaminated by blue green algal toxins merits further investigation. 相似文献
469.
Ana María Chaux-Gutiérrez Ezequiel José Pérez-Monterroza Vânia Regina Nicoletti Telis Maria Aparecida Mauro 《Food biophysics》2017,12(1):69-77
The thermal behavior, moisture adsorption properties and structural and morphological characteristics of mango powders were evaluated. The powders were obtained by foam mat drying methodology using albumin (ALB), mixture (EB) of monoglycerides of fatty acids, sorbitan monostearate and polyoxyethylene sorbitan monostearate and a combination of the two (EB-ALB) as foaming agents. The evaluation was done by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the moisture adsorption isotherms were also determined. The powder with EB had a glass transition temperature (Tg) of ?4.2 °C. The denaturation temperature of pure albumin (82.2 °C) increased in the powders with ALB to 117 °C and in those with EB-ALB to 102 °C, due to the thermal stability provided by the pulp sugars. The moisture sorption isotherm of the EB-powder showed a higher water equilibrium content than the other powders. All the powders were in the amorphous state. The morphology of the powder with EB showed corrugated particles, whereas those with ALB and EB-ALB showed particles with a less porous aspect and more compact surfaces than the powders with EB. 相似文献
470.