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21.
Extraction of whole lobes of normal rat liver with dimethyl sulphoxide (DMSO) under N2 gives extracts which contain 5—10 μmol/l·O?2 (50-100 nmol·O?2 per 10 ml extract per 4 g liver; 1.25-2.50 nmol·O?2 per millilitre per gram liver). Evidence for ·O?2 in the extracts is given by: (1) electron spin resonance signals (ESR), (2) differential pulse polarography (DPP), (3) chemiluminescence (CL), and (4) nitroblue tetrazolium reduction (NBT). All tests yield results identical with those obtained with authentic ·O?2. Extraction of ·O?2 is enhanced by tetrabutyl ammonium ion, and is maximal at 1-3 min. These results raise the possibility that substantial amounts of ·O?2 are normally sequestered in protective membranous sites in vivo. 相似文献
22.
Oscar Lazcano Jorge Bilbao Robert S. Beissner Martha Vandiver Chin Yang Li 《Biotechnic & histochemistry》1992,67(1):14-20
Permanent preparations of air dried synovial fluids were prepared by staining calcium compounds with alizarin red S stain; each slide was coverslipped with Permount. Variables studied were: (a) concentration of the solution of alizarin red S, (b) pH of staining solution, (c) time of incubation in staining solution and aqueous and ethanolic content of staining solution. The staining effect of each solution was tested on calcium pyrophosphate dihydrate, calcium oxalate, apatite and monosodium urate (MSU). Of all the solutions, best results were obtained with 0.25% alizarin red S in 50% ethanol at pH 7.0 for 30 min. With this solution, the calcium-containing compounds were well stained. MSU did not stain and still preserved negative birefringence on polarizaton. Fixation of smears with ethanol served a double purpose: It fixed the slides without dissolving or removing MSU or the calcium compounds, yet it did dissolve five corticosteroids commonly used for intra-articular injection which may interfere with interpretation of compensated polarized light microscopy of synovial fluids. 相似文献
23.
We examined the effect of ovule position within the ovary on the probability of seed maturation, on seed weight, and on progeny performance in the outbreeding legume Phaseolus coccineus. Ovaries of P. coccineus possess six linearly arranged ovules (ovule position one = stylar end). We found that in both 1987 and 1988, ovule position had a significant effect on the probability of seed maturation under field conditions. In 1987, ovule positions one. two, and three had a higher probability of maturing seeds than the three most basal ovule positions. In 1988, the probability of producing a mature seed in ovule position one was more similar to the three most basal ovule positions than to ovule positions two and three. The position of the ovule in the ovary had no significant effect on seed weight in 1987, but it had a significant effect in 1988. Overall, seeds from ovule positions one, two, and three tended to produce heavier seeds than the three most basal ovule positions. The effects of ovule position on progeny performance were determined in a greenhouse and a field study. In the greenhouse study, we found no significant overall effect of the position of the ovule that produced the seed on progeny performance. In the field study, we did find a significant ovule position effect on several measures of reproductive performance as well as an overall effect on reproductive performance. In addition, we found a significant interaction between ovule position and number of seeds per fruit. Progeny from the stylar end of the fruit outperformed the progeny from the peduncular end in fruits containing many seeds, whereas there were no significant differences between progeny produced in the stylar and peduncular ends of fruits containing few seeds. Causes of position effects are unknown but hypotheses abound. 相似文献
24.
R. Rodney Howell Amir I. Arbisser David S. Parsons Charles I. Scott Ursula Fraustadt William R. Collie Robert N. Marshall Oscar Cavazos Ibarra 《American journal of human genetics》1981,33(6):957-967
We have defined a new autosomal recessive disorder in patients stemming from a small community in northern Mexico. Diagnosable at birth, its major symptoms include brittle hair, mental retardation, and nail dysplasia. Structural hair abnormalities are seen by both light and electron microscopy. Hair cystine content is reduced while the copper/zinc ratio in hair is increased. 相似文献
25.
Intermediate Filaments of Schwann Cells 总被引:9,自引:4,他引:5
Lucila Autilio-Gambetti Jack Sipple Oscar Sudilovsky Pierluigi Gambetti 《Journal of neurochemistry》1982,38(3):774-780
Abstract: Intermediate filaments were prepared from distal stumps of rabbit sciatic nerve 5 weeks after nerve section, at which time Schwann cells account for 85–90% of the cell area. A polypeptide of molecular weight 58,000 was the main component of this fraction. An antiserum raised in guinea pig against this polypeptide stained all cells present in the distal stump, as well as Schwann cells and 3T3 cells in culture. The identity of the molecular weight 58,000 polypeptide obtained from distal stumps with vimentin was proved with one and two-dimensional sodium dodecyl sulfate pol yacrylamide gel electrophoresis and with immunoautoradiography. It is concluded that the intermediate filament subunit of undifferentiated Schwann cells is vimentin. The possibility that Schwann cells in normal nerve may have another type of intermediate filament besides vimentin cannot be ruled out. 相似文献
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Summary Transepithelial Li+ influx was studied in the isolated epithelium from abdominal skin ofRana catesbeiana. With Na+-Ringer's as inside medium and Li+-Ringer's as outside medium, the Li+ influx across the epithelium was 15.6 A/cm2. This influx was considerably reduced by removal of either Na+ or K+ from the inside bath or by the addition of ouabain or amiloride. Epithelial K+ or Na+ concentration was respectively lower in epithelia bathed in K+-free Ringer's or Na+-free Ringer's. In conditions of negligible Na+ transport, a 20mm Li+ gradient (outin) produced across the short-circuited epithelium a Li+ influx of 11.8 A/cm2 and a mean short-circuit current of 10.2 A/cm2. The same Li+ gradient in the opposite direction produced a Li+ outflux of only 1.9 A/cm2. With equal Li+ concentration (10.3 and 20.6mm) on both sides of the epithelium, plus Na+ in the inside solution only, a stable Li+-dependent short-circuit current was observed. Net Li+ movement (outin) was also indirectly determined in the presence of an opposing Li+ gradient. Although Li+ does not substitute for Na+ as an activator of the (Na++K+)-ATPase from frog skin epithelium, Li+ influx appears to be related to Na+–K+ pump activity. It is proposed that the permeability of the outer barrier to Na+ and Li+ is regulated by the electrical gradient produced by electrogenic Na+–K+ pumps located in the membrane of the deeper epithelial cells. 相似文献
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30.
Biofilm formation and dispersal in Gram-positive bacteria 总被引:1,自引:0,他引:1
Biofilms are structured communities of bacteria, which are adhered to a surface and embedded in a self-produced matrix of extracellular polymeric substances. Since biofilms are very resistant to antimicrobial agents, they are at the basis of a range of problems, including quality and safety issues in food industry. Recently, major advances have been made in elucidating the different structural components of the biofilm matrix, the regulatory pathways involved in biofilm formation, and signaling molecules involved in biofilm formation and dispersal, which provide opportunities for prevention and control of these biofilms in the food industry. 相似文献