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51.
Amino acid sequences of neurotoxins RTX-IV and RTX-V isolated from the sea anemone Radianthus macrodactylus were determined by the automated Edman degradation; their polypeptide chains consist of 48 and 47 amino acid residues, respectively. For identification of tryptophan-30 in toxin RTX-IV, its trypsin and chymotrypsin digests were investigated. Amino acid sequences of the above toxins show that they belong to a new structural class and that C-terminal positive charge and tyrosine-25 are important for toxic activity of sea anemone polypeptides.  相似文献   
52.
The history of some invasive species is so complex that their origins can be difficult to determine. One example of such invasive species is the California invasive known as “wild artichoke thistle” (Cynara cardunculus var. sylvestris), found in natural and disturbed ecosystems. Wild artichoke thistle is a Mediterranean native and the progenitor of two domesticated horticultural taxa, artichoke and cardoon. Different hypotheses regarding the origins of California plants have included introductions by 19th century Italian immigrants and the de-domestication (evolutionary reversion to wild-type morphology) of feral (escaped, free-living) cultivars. Using microsatellite markers, we compared the genetic constitutions of 12 artichoke thistle populations in California with possible progenitor populations: 17 Spanish and Italian wild populations and eight different artichoke and cardoon cultivars. Each California population was compared with its putative progenitors using STRUCTURE analysis. Our results suggest that California's artichoke thistle populations are polyphyletic. Surprisingly, two-thirds of California's populations closely matched populations from the Iberian Peninsula. Three populations matched domesticated artichoke. One population appears to have wild and cultivar hybrid ancestry. Alleles specific to Italian populations were found at low frequencies in some California plants, suggesting that Italian wild plants may have been in California, but have left a trivial genetic legacy. Given that the de-domesticated plants in this study appear to be as invasive as the wild taxon, we conclude with a discussion of the role that ferality and de-domestication may have in plant invasions.  相似文献   
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It has been found that the Soviet anticonvulsant drug Benzonal is an inducer of the liver cytochrome P-450 of the phenobarbital type. The drug causes formation of the cytochrome P-450 form which is immunologically identical to the phenobarbital inducible form of the hemoprotein with identical molecular mass determined with the SDS-gel electrophoresis method in PAAG. The microsomes, obtained from the rats treated with Benzonal display increased rates of metabolism of 7-pentoxiresorufin and 16 beta-hydroxylation of androstenedione which are specific substrates for the cytochrome P-450b.  相似文献   
55.
Abstract: The Jurassic was an important period in the evolution of Testudinata and encompasses the origin of many clades, and this is especially true of Jurassic turtles from Western Europe. A new genus and species of Late Jurassic turtle, Hispaniachelys prebetica gen. et sp. nov. from the upper Oxfordian of the Prebetic (Southern Spain), is described on the basis of postcranial material. The specimen is the only known tetrapod from the Mesozoic of the Prebetic and the oldest turtle from southern Europe. A mosaic of characters indicates this is a new genus: it displays basal features including dorsal epiplastral processes/reduced cleithra, no medial contact of the extragulars and a long first thoracic rib, alongside derived characters including an absence of mesoplastra and the vertebral 3/4 sulcus crossing neural 5. The phylogenetic position of the new taxon is hard to resolve, and it might be either a paracryptodire or a basal testudine, but it is distinct from Plesiochelys. A complex taphonomic history is shown by a range of overlying grazing traces and bioerosion on the carapace. The carapace was subsequently overturned and buried ventrally up, terminating grazing activity, and was then bored by sponges before final burial. Scanning electron microscopy reveals phosphatic microspheroids associated with bacterial decay in the vascular cavities of the cancellous bone, suggesting the carapace may have acted as a closed microenvironment in which decay‐derived authigenic minerals formed.  相似文献   
56.
Research laboratories studying the genetics of companion animals have no database tools specifically designed to aid in the management of the many kinds of data that are generated, stored and analyzed. We have developed a relational database, "DOG-SPOT," to provide such a tool. Implemented in MS-Access, the database is easy to extend or customize to suit a lab's particular needs. With DOG-SPOT a lab can manage data relating to dogs, breeds, samples, biomaterials, phenotypes, owners, communications, amplicons, sequences, markers, genotypes and personnel. Such an integrated data structure helps ensure high quality data entry and makes it easy to track physical stocks of biomaterials and oligonucleotides.  相似文献   
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A new tool for locomotor circuitry activation in the non-injured human by transcutaneous electrical spinal cord stimulation (tSCS) has been described. We show that continuous tSCS over T11-T12 vertebrae at 5-40 Hz induced involuntary locomotor-like stepping movements in subjects with their legs in a gravity-independent position. The increase of frequency of tSCS from 5 to 30 Hz augmented the amplitude of evoked stepping movements. The duration of cycle period did not depend on frequency of tSCS. During tSCS the hip, knee and ankle joints were involved in the stepping performance. It has been suggested that tSCS activates the locomotor circuitry through the dorsal roots. It appears that tSCS can be used as a non-invasive method in rehabilitation of spinal pathology.  相似文献   
59.
Hydroxyurea was used to study the proliferation rate of haemopoietic stem cells (CFUJ in normal mice, after irradiation or transplantation into irradiated recipients. It was demonstrated that the proliferation rate of endogenous CFUS (endo-CFU,) and exogenous CFUS (exo-CFUs) are identical. After irradiation (650 R) the surviving endo-CFUs begin to proliferate immediately. By contrast exo-CFU, transplanted into the irradiated recipient mouse (850 R), begin to proliferate only after about 30 hr. However, injection of isoproterenol (which stimulates adenyl cyclase) or dibutyryl cyclic adenosine 3′,5′-monophosphate shortly after marrow cell graft, triggers the transplanted CFUS into cell cycle as shown by an almost immediately increased sensitivity to hydroxyurea. Isoproterenol is capable of inducing DNA synthesis also in stem cells of normal mice but it takes about 20 hr before CFU, become to be increasingly sensitive to hydroxyurea.  相似文献   
60.
Results of Russian-Austrian space experiment "Monimir" which was a part of international space program "Austromir" are presented in this paper. Characteristics of horizontal gaze fixation reaction (hGFR) to visual targets were analyzed. Seven crewmembers of "Mir" space station expeditions took part in the experiment. Experiments were carried out 4 times before space flight, 5 times in flight and 3-4 times after landing. There were revealed significant alterations in characteristics of gaze fixation reaction during flight and after its accomplishing, namely: an increase of the time of gaze fixation to the target, changes of eye and head movements' velocity and increase of the gain of vestibular-ocular reflex, that pointed out to the disturbances of the control mechanisms of vestibular-ocular reflex in weightlessness caused by changes of vestibular input's activity. There was discovered also the difference in the strategies of adaptation to microgravity conditions among the cosmonauts of flight and non-flight occupation: in the first group exposure to weightlessness was accompanied by gaze hypermetry and inhibition of head movements; in the second one--on the contrary--by increase of head movement velocity and decrease of saccades' velocity.  相似文献   
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