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31.
Specific language impairment (SLI) is a common developmental disorder characterized by difficulties in language acquisition despite otherwise normal development and in the absence of any obvious explanatory factors. We performed a high-density screen of SLI1, a region of chromosome 16q that shows highly significant and consistent linkage to nonword repetition, a measure of phonological short-term memory that is commonly impaired in SLI. Using two independent language-impaired samples, one family-based (211 families) and another selected from a population cohort on the basis of extreme language measures (490 cases), we detected association to two genes in the SLI1 region: that encoding c-maf-inducing protein (CMIP, minP = 5.5 × 10−7 at rs6564903) and that encoding calcium-transporting ATPase, type2C, member2 (ATP2C2, minP = 2.0 × 10−5 at rs11860694). Regression modeling indicated that each of these loci exerts an independent effect upon nonword repetition ability. Despite the consistent findings in language-impaired samples, investigation in a large unselected cohort (n = 3612) did not detect association. We therefore propose that variants in CMIP and ATP2C2 act to modulate phonological short-term memory primarily in the context of language impairment. As such, this investigation supports the hypothesis that some causes of language impairment are distinct from factors that influence normal language variation. This work therefore implicates CMIP and ATP2C2 in the etiology of SLI and provides molecular evidence for the importance of phonological short-term memory in language acquisition.  相似文献   
32.
First identified by the Egyptians in 2640 BC, podagra (acute gout occurring in the first metatarsophalangeal joint) was later recognized by Hippocrates in the fifth century BC, who referred to it as 'the unwalkable disease'. The term is derived from the Latin word gutta (or 'drop'), and referred to the prevailing medieval belief that an excess of one of the four 'humors'--which in equilibrium were thought to maintain health--would, under certain circumstances, 'drop' or flow into a joint, causing pain and inflammation. Throughout history, gout has been associated with rich foods and excessive alcohol consumption. Because it is clearly associated with a lifestyle that, at least in the past, could only be afforded by the affluent, gout has been referred to as the 'disease of kings'. Although there is evidence that colchicine, an alkaloid derived from the autumn crocus (Colchicum autumnale), was used as a powerful purgative in ancient Greece more than 2000 years ago, its first use as a selective and specific treatment for gout is attributed to the Byzantine Christian physician Alexander of Tralles in the sixth century AD. Uricosuric agents were first used at the end of the 19th century. In the modern era, nonsteroidal anti-inflammatory drugs are usually the drugs of choice for treating acute gout. Perhaps the most important historical advance in the treatment of hyperuricemia was the development of xanthine oxidase inhibitors, which are effective in reducing plasma and urinary urate levels and have been shown to reverse the development of tophaceous deposits.  相似文献   
33.
The objective of this study was to develop nonsurgical methods of embryo collection and transfer in domestic rabbits (Oryctolagus cuniculus) and domestic ferrets (Mustela putorius furo) to serve as models for use in mammals in which surgical procedures are the usual means for applying embryo transfer technology. Specially designed transcervical catheters were used together with a fibre optic endoscope to visualize and then catheterize the rabbit and ferret cervices. Five consecutive transcervical uterine flushes in each of eight superovulated female rabbits 78-89 h after an ovulatory injection of LH resulted in the retrieval of 187 embryos, for an average of 23 embryos per rabbit. A total of 116 embryos were nonsurgically transferred to the uteri of ten recipients, and resulted in 23 young (20%). Eight rabbits (80%) produced young with an average litter size of 2.88 (range 1-7). Ten consecutive transcervical uterine flushes in each of 37 female ferrets 145-178 h after an ovulatory injection of hCG resulted in the retrieval of 324 embryos, an average of 8.76 embryos per ferret. A total of 251 embryos from 27 donors were nonsurgically transferred to the uteri of 31 recipients, and resulted in 65 young (26%). Twenty-eight of the recipients (90%) were initially pregnant, as indicated by postpartum necropsies, and twenty-two ferrets (71%) produced young. The average litter size was 2.95 (range 1-7). This is the first report of live births resulting from the nonsurgical collection of embryos from a donor followed by nonsurgical transfer of those same embryos to a synchronous recipient. The methods reported here can serve as models for use in other mammals in which direct visualization and manipulation of the cervix are not possible, and will be particularly useful in endangered species.  相似文献   
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Permanent cannulation systems designed for injecting spermatozoa or for collecting eggs and fluids at the tubo-uterine junction and at the ampulla near its junction with the isthmus of the oviduct are described. In a preliminary experiment three ewes bilaterally cannulated in the tubouterine junction had spermatozoa injected through the cannulae and 4 of 8 eggs recovered were fertilized. Six more ewes were bilaterally cannulated. They continued to cycle and few complications were experienced. But cannulation appeared to reduce superovulatory response to exogenous gonadotropins. This also occurred in a confirmatory study with 16 rabbits in which super-ovulated controls averaged 25.6 ovulations versus 8.6 in those with cannulae. When cannulae were installed near the ampullar-isthmic junction no eggs were recovered surgically from 4 controls. Thus, these cannulae appeared to interfere with ampullary transport of eggs.Blood plasma concentrations of LH and progesterone were not affected by cannulae. As cycle length also was normal it appeared that these devices were not luteolytic.The cannulae were still functioning in the animals euthanized more than six months after installation. Thus, once installed, they appear to offer a non-surgical means of examining several aspects of reproductive function associated with fertilization. The observations on altered egg transport and ovarian response to gonadotropins may be of significance in certain cases of infertility.  相似文献   
36.
Four experiments were conducted to test the effects of Eagle's non-essential amino acids (NEAA) and essential amino acids (EAA), glycine, and the RNA polymerase inhibitor α-amanitin, on the development of preimplantation rabbit embryos in modified protein-free KSOM medium. Embryos were distributed randomly into different treatments and cultured in 5% O2:5% CO2:90% N2. In experiment 1, 100% of the embryos became blastocysts in the medium with Eagle's IX NEAA and 0.5X EAA, but 100% stopped development at the morula stage in KSOM without amino acids. These morulae failed to develop further when transferred to amino acid supplemented medium after 72 hr of culture. Glycine alone in modified KSOM (experiment 2) was ineffective in supporting development of 8–16-cell stage embryos past the morula stage. In experiment 3, the addition of IX NEAA and 0.5X EAA at 0, 12, 24, 36, and 48 hr of culture resulted, respectively, in 57, 65, 65, 44, and 14% blastocysts on Day 3 (P<0.05) and 86, 77, 77, 78, and 69% on Day 5 (P<0.05). Omission of Eagle's amino acids until 48 hr clearly delayed embryo development. In experiment 4, when α-amanitin (20 μM) was added to the medium containing Eagle's amino acids after 0, 12, 24, 36, and 48 hr of culture most embryos cleaved only once or twice after adding the α-amanitin. Without the inhibitor, 94% of the zygotes developed into blastocysts. These results indicate that modified KSOM or KSOM plus glycine could not support rabbit embryo development past the morula stage, but this block was overcome by adding Eagle's amino acids. An exogenous source of amino acids was not critical for embryo development during the first 24 hr of culture, but was required after that for development to equal controls. Addition of α-amanitin at multiple pre-blastocyst stages limited further embryo development to one or two cleavage divisions, with no blastocyst development. © 1996 Wiley-Liss, Inc.  相似文献   
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Candida guilliermondii is an ascomycetous yeast widely studied due to its clinical importance, biotechnological interest, and biological control potential. During a series of preliminary experiments aiming at optimizing the electroporation procedure of C. guilliermondii cells, we observed that the efficiency of transformation of an ura5 recipient strain with the corresponding dominant marker URA5 was more than a thousand fold higher as compared with the transformation of an ura3 strain with the URA3 wild type allele. This result allowed the identification of an autonomously replicating sequence (ARS) within an A/T rich region located upstream of the URA5 open reading frame (ORF). Interestingly, linear double strand DNAs (dsDNAs) containing this putative ARS are circularized and then autonomously replicated in C. guilliermondii transformed cells. We demonstrated that the C. guilliermondii Lig4p ligase, involved in the canonical non-homologous end-joining (NHEJ) pathway, was responsible for this phenomenon since a lig4 mutant was unable to circularize and to autonomously maintain transforming dsDNAs containing the putative ARS. Finally, a functional dissection of the C. guilliermondii A/T rich region located upstream of the URA5 ORF revealed the presence of a 60 bp-length sequence essential and sufficient to confer ARS properties to shuttle plasmid and linear dsDNAs.  相似文献   
39.
Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus–cuticle interactions related to substrate utilization and resistance to host‐specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell‐free filtrate, for which activity of elastase, N‐acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N‐glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions.  相似文献   
40.
1. Studies were carried out to determine the cellular and subcellular site of biosynthesis of components of fraction I, an alpha-globulin fraction containing acidic glycoproteins isolated from guinea-pig serum. l-[U-(14)C]Leucine or -valine and d-[1-(14)C]glucosamine were used as precursors. 2. A lag of about 10min. occurred before appreciable label appeared in fraction I of serum after injection of leucine or glucosamine. Label in fraction I after 60min. labelling with glucosamine was present almost entirely in hexosamine and sialic acid. 3. Site of synthesis was investigated by studies in vivo up to 17min. after injection of precursor. Particulate subcellular fractions isolated from liver, spleen and kidney or homogenates of the latter two tissues were extracted with Lubrol. Extracts were allowed to react by double diffusion with antisera to fraction I or to subfractions isolated from it, and gels were subsequently subjected to radioautography. With either amino acid or glucosamine as precursor, only extracts of the microsome fraction of liver formed precipitin lines that were appreciably radioactive. 4. The role of the microsome fraction of liver in the synthesis of these glycoproteins was confirmed by immunological studies after incubation of liver slices with leucine or glucosamine. Incorporation of leucine was also investigated in a cell-free microsome system. 5. Material was also precipitated from certain Lubrol extracts of liver microsomes by direct addition of antiserum and its radioactivity measured. Degradation of material thus precipitated and use of heterologous immune systems showed that labelling of precipitin lines represented biosynthesis. 6. A study of extraction procedures suggested that the substances present in the microsome fraction of liver that react with specific antisera are associated with membranous structures. 7. Most or all precipitin lines formed by Lubrol extracts of liver microsomes interacted with precipitin lines given by guinea-pig serum or fraction I, immunological identity being apparent with some lines. The microsome-bound substances thus represent serum glycoproteins or precursors of them. 8. The distribution of label in various tissues and in the protein of subcellular fractions of liver after administration of [(14)C]glucosamine to the guinea pig was also studied. Some variation in results obtained with liver was found depending on the fractionation medium used.  相似文献   
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