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1.
The development of changes in visual orientation, posture, activity budgets, and behavioral milestones was examined in five bongo calves which were observed from birth to 4 or 6 months of age. The only significant change in the calves' visual orientation was an increase in orientation to food. Reclining declined significantly over weeks, while standing increased and moving did not change. Overall, stationary behaviors dominated the activity budget, but decreased significantly over the study. The category that included locomotion, object exploration, and auto-play did not change, while forage and rumination increased significantly. Contrary to expectation, the decline in suckling was not significant. Affiliative interactions with the dam decreased significantly during the study, but increases in affiliation with other bongos were not significant. Levels of agonistic behavior between the calves and their dams and other herd members were low throughout the study, and did not change significantly. One female calf achieved several developmental milestones later than the others. It is suggested that these differences may have been influenced by the dominance status of her dam. The results conform to the general developmental pattern of “hider” bovids. Bongos, however, show somewhat different patterns of social development than eland, which are reported to be more precocial in expression of aggressive and sexual behaviors. © 1992 Wiley-Liss, Inc.  相似文献   
2.
    
Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease, characterized by progressive dysfunction and death of motor neurons. Although evidence for oxidative stress in ALS pathogenesis is well described, antioxidants have generally shown poor efficacy in animal models and human clinical trials. We have developed an in vitro screening cascade to identify antioxidant molecules capable of rescuing NSC34 motor neuron cells expressing an ALS-associated mutation of superoxide dismutase 1. We have tested known antioxidants and screened a library of 2000 small molecules. The library screen identified 164 antioxidant molecules, which were refined to the 9 most promising molecules in subsequent experiments. Analysis of the in silico properties of hit compounds and a review of published literature on their in vivo effectiveness have enabled us to systematically identify molecules with antioxidant activity combined with chemical properties necessary to penetrate the central nervous system. The top-performing molecules identified include caffeic acid phenethyl ester, esculetin, and resveratrol. These compounds were tested for their ability to rescue primary motor neuron cultures after trophic factor withdrawal, and the mechanisms of action of their antioxidant effects were investigated. Subsequent in vivo studies can be targeted using molecules with the greatest probability of success.  相似文献   
3.
Mourning doves (Zenaida macroura) are the most abundant and widespread native member of the columbid family, as well as a major migratory game species, in the United States. However, there is little information on mortality factors in mourning doves. Records of necropsy accessions at the Southeastern Cooperative Wildlife Disease Study (SCWDS) from 15 southeastern states, from 1971 through 2005, were reviewed. One hundred thirty-five mourning doves were submitted from nine states during the 35-yr period. Trichomonosis constituted 40% (n = 54) of all diagnoses and was the most frequent diagnosis. Toxicoses and avian pox constituted 18.5% (n = 25) and 14.8% (n = 20) of all diagnoses, respectively. Remaining diagnoses included trauma, suspected toxicosis, Ascaridia columbae infection, suspected tick paralysis, and undetermined. Adults were observed more frequently with trichomonosis (94.1%) and toxicoses (68%) as compared to juveniles, but a gender predisposition was not apparent for either disease. Age and gender predilections were not apparent for cases of avian pox. The majority of the trichomonosis and avian pox cases were observed in the spring-summer, whereas the majority of the toxicosis cases were observed in the winter-spring. Additionally, the Georgia Department of Human Resources-Division of Public Health and West Virginia Department of Health and Human Resources submitted 809 mourning doves to SCWDS from 2001 through 2005 for West Nile virus surveillance efforts. West Nile virus was isolated from 2.1% (n = 17) and eastern equine encephalitis virus (EEEV) was isolated from 0.2% (n = 2) of the submitted birds.  相似文献   
4.
5.
Chromosomal DNA from 5 isolates of Cryptosporidium parvum and 1 of C. baileyi were compared by field-inversion gel electrophoresis (FIGE). FIGE analyses of parasite DNA prepared from purified sporozoites versus intact oocysts showed no observable differences. Chromosomal DNA migration patterns of the 5 C. parvum isolates were indistinguishable, whereas similar but distinct differences were evident between C. baileyi and the isolates of C. parvum. Oocyst-reactive monoclonal antibodies differentiated oocysts of C. parvum from those of C. baileyi but were unable to distinguish oocysts of 1 isolate of C. parvum from another.  相似文献   
6.
  总被引:16,自引:17,他引:16  
Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.  相似文献   
7.

Background

ExCyto PCR cells provide a novel and cost effective means to amplify DNA transformed into competent bacterial cells. ExCyto PCR uses host E. coli with a chromosomally integrated gene encoding a thermostable DNA polymerase to accomplish robust, hot-start PCR amplification of cloned sequences without addition of exogenous enzyme.

Results

Because the thermostable DNA polymerase is stably integrated into the bacterial chromosome, ExCyto cells can be transformed with a single plasmid or complex library, and then the expressed thermostable DNA polymerase can be used for PCR amplification. We demonstrate that ExCyto cells can be used to amplify DNA from different templates, plasmids with different copy numbers, and master mixes left on ice for up to two hours. Further, PCR amplification with ExCyto cells is comparable to amplification using commercial DNA polymerases. The ability to transform a bacterial strain and use the endogenously expressed protein for PCR has not previously been demonstrated.

Conclusions

ExCyto PCR reduces pipetting and greatly increases throughput for screening EST, genomic, BAC, cDNA, or SNP libraries. This technique is also more economical than traditional PCR and thus broadly useful to scientists who utilize analysis of cloned DNAs in their research.  相似文献   
8.
Electrical Characteristics of Sphingomyelin Bilayer Membranes   总被引:1,自引:0,他引:1       下载免费PDF全文
Current-voltage characteristics and the conductivity temperature dependence of sphingomyelin bilayer membranes have been determined. The resistances were of the order of 10(8) Omega-cm(2) and exhibited ohmic behavior up to approximately 25 mv followed by increasing conductivity with applied voltage. The current is found to be proportional to a hyperbolic sine function of the voltage. The temperature dependence indicates a thermally activated conduction mechanism. The observed behavior closely follows a kinetic model involving a barrier modified by the applied electric field, the rate-limiting process being the surmounting of the barrier by the impinging ions. The model allows predictions to be made over a wide range of conditions.  相似文献   
9.
10.
Mesoplodon peruvianus , a new species of beaked whale, is described on the basis of ten specimens which have either stranded or been captured between 11°12'S and 15°19'S latitude along the coasts of the provinces of Lima and Ica, south central Peru. This is the thirteenth living species of Mesoplodon recognized in the world's oceans. The animals that were examined were uniformly gray above, shading to lighter gray below. This whale is the smallest species of Mesoplodon (maximum body length 3.72 m) and is characterized by its teeth, which are small (31 to 65 mm long), ovate in cross section, and positioned 2.5% to 8.4% of the mandibular length from the anterior extremity, and posterior to the mandibular symphysis.  相似文献   
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