首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   122篇
  免费   1篇
  2022年   1篇
  2020年   1篇
  2018年   1篇
  2016年   1篇
  2015年   7篇
  2014年   6篇
  2013年   9篇
  2012年   11篇
  2011年   10篇
  2010年   7篇
  2009年   8篇
  2008年   9篇
  2007年   7篇
  2005年   1篇
  2004年   1篇
  2003年   1篇
  2001年   5篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1992年   1篇
  1991年   1篇
  1990年   1篇
  1989年   2篇
  1987年   2篇
  1986年   2篇
  1985年   1篇
  1983年   2篇
  1982年   2篇
  1980年   2篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1974年   1篇
  1970年   1篇
  1968年   1篇
排序方式: 共有123条查询结果,搜索用时 15 毫秒
21.
Summary Intercellular junctions in the uterine epithelium of the ovoviviparous urodele Salamandra salamandra were studied in pregnant and non-pregnant females by freeze-fracture technique. Junctional complexes consist of zonulae occludentes (tight junctions) and numerous maculae adhaerentes (desmosomes); z. adhaerentes and nexuses (gap junctions) could not be identified. Tight junctions are of the flexible type exhibiting loosely interconnected fibrils. The fibrillary network appears stretched more often in pregnant females possibly due to the mechanical stress of pregnancy. The structure and occurrence of the junctions identified, especially that of the tight junctions, is discussed with regard to the functions of the uterus during pregnancy.Zusammenfassung Mit Hilfe der Gefrierbruchtechnik wurden im Uterus-epithel trächtiger und nichtträchtiger Feuersalamanderweibchen (Salamandra salamandra) Zonulae occludentes und Maculae adhaerentes, jedoch keine Z. adhaerentes sowie Nexus identifiziert. Die Z. occludentes sind flexibel. Ihr fibrilläres Netzwerk ist bei trächtigen Weibchen öfter gestreckt; das ist möglicherweise auf die stärkere Ausdehnung des Uterusgewebes während der Trächtigkeit zurückzuführen. Das Vorkommen der verschiedenen Kontakt-strukturen, namentlich das der Z. occludentes, wird im Hinblick auf die Funktionen des Uterus während der Trächtigkeit diskutiert.We are indebted to Mrs. K. Ott for excellent technical assistance and to Miss Dr. U. Beigel for linguistic help  相似文献   
22.
Summary We recently described a nonradioactive method for in situ hybridization with 5-bromo-2-deoxyuridine (BrdU) labelled oligonucleotide probes. An antibody to BrdU and immunocytochemistry were used in order to detect the hybridization signal. We have now applied this method to semithin Epon sections, in order to hybridize consecutive sections through single cells with different probes and to stain them with antibodies to neuropeptides. It could be shown that Epon embedding preserves mRNA well. In the present study we used a BrdU labelled synthetic oligonucleotide probe complementary to a fragment of the vasopressin precursor and an antibody to Arg-vasopressin. Vasopressin mRNA was demonstrable in a fraction of the vasopressin immunoreactive neurons in the magnocellular nuclei. In addition some of the magnocellular neurons showed either hybridization or vasopressin immunostaining only, perhaps indicating different stages of synthetic and secretory activity. The method described seems to be a valuable tool for studying synthetic activity in peptidergic neurons on a single cell level. The method might also have potential for in situ hybridization on the electronmicroscopical level.  相似文献   
23.
24.
Tailor‐made microorganisms Microbial diversity provides unlimited resources for the development of novel industrial processes and products. Since the beginning of the 20th century microorganisms have been successfully applied for the large scale production of bio‐based products. In recent years, modern methods of strain development and Synthetic Biology have enabled biotech engineers to design even more sophisticated and tailor‐made microorganisms. These microbes serve industrial processes for the production of bulk chemicals, enzymes, polymers, biofuels as well as plant‐derived ingredients such as Artemisinin in an ecologically and economically sustainable and attractive fashion. In the future, production of advanced biofuels, microbial fuel cells, CO2 as feedstock and microbial cellulose are research topics as well as challenges of global importance. Continuous efforts in microbiology and biotechnology research will be pivotal for white biotechnology to gain more momentum in transforming the chemical industry towards a knowledge based bio‐economy.  相似文献   
25.
ABSTRACT: BACKGROUND: The increasing trend for incorporation of biological sample collection within clinical trials requires sample collection procedures which are convenient and acceptable for both patients and clinicians. This study investigated the feasibility of using saliva-extracted DNA in comparison to blood-derived DNA, across two genotyping platforms: Applied Biosystems Taqman TM and Illumina Beadchip TM genome-wide arrays. METHOD: Patients were recruited from the Pharmacogenetics of Breast Cancer Chemotherapy (PGSNPS) study. Paired blood and saliva samples were collected from 79 study participants. The Oragene DNA Self-Collection kit (DNAgenotek(R)) was used to collect and extract DNA from saliva. DNA from EDTA blood samples (median volume 8 ml) was extracted by GenProbe, Livingstone, UK. DNA yields, standard measures of DNA quality, genotype call rates and genotype concordance between paired, duplicated samples were assessed. RESULTS: Total DNA yields were lower from saliva (mean 24 ug, range 0.2-52 ug) than from blood (mean 210 ug, range 58-577 ug) and a 2-fold difference remained after adjusting for the volume of biological material collected. Protein contamination and DNA fragmentation measures were greater in saliva DNA. 78/79 saliva samples yielded sufficient DNA for use on Illumina Beadchip arrays and using Taqman assays. Four samples were randomly selected for genotyping in duplicate on the Illumina Beadchip arrays. All samples were genotyped using Taqman assays. DNA quality, as assessed by genotype call rates and genotype concordance between matched pairs of DNA was high (>97%) for each measure in both blood and saliva-derived DNA. CONCLUSION: We conclude that DNA from saliva and blood samples is comparable when genotyping using either Taqman assays or genome-wide chip arrays. Saliva sampling has the potential to increase participant recruitment within clinical trials, as well as reducing the resources and organisation required for multicentre sample collection.  相似文献   
26.
The use of whips by jockeys is an issue. The current study viewed opportunistic high-speed footage of 15 race finishes frame-by-frame to examine the outcomes of arm and wrist actions (n = 350) on 40 horses viewed from the left of the field. Any actions fully or partially obscured by infrastructure or other horses were removed from the database, leaving a total of 104 non-contact sweeps and 134 strikes. For all instances of arm actions that resulted in fully visible whip strikes behind the saddle (n = 109), the outcomes noted were area struck, percentage of unpadded section making contact, whether the seam made contact and whether a visible indentation was evident on impact. We also recorded use of clockwise or counter-clockwise arm action from each jockey''s whip, whether the whip was held like a tennis racquet or a ski pole, whether the hind leg on the side of the impact was in stance or swing phase and whether the jockey''s arm was seen traveling above shoulder height. The goal of the study was to characterize the area struck and the visual impact of whip use at the level of the horse. We measured the ways in which both padded and unpadded sections of the whip made impact. There was evidence of at least 28 examples, in 9 horses, of breaches of the whip rules (one seam contact, 13 contacts with the head, and 14 arm actions that rose above the height of the shoulder). The whip caused a visible indentation on 83% of impacts. The unpadded section of the whip made contact on 64% of impacts. The results call into question the ability of Stewards to effectively police the rules concerning whip use and, more importantly, challenge the notion that padding the distal section of whips completely safeguards horses from any possible whip-related pain.  相似文献   
27.
Juvenile myelomonocytic leukemia (JMML) is a unique myeloproliferative disorder of early childhood in which mutations in NRAS, KRAS, PTPN11, NF1 and CBL are frequently found. Using high-resolution oligo array-based comparative genomic hybridization (aCGH), 20 JMML samples were investigated for submicroscopic genomic copy number alterations. Besides known cytogenetic aberrations, ten samples displayed additional submicroscopic alterations. Interestingly, an almost identical gain of chromosome 8 was identified in two patients. Subsequently, fluorescence in situ hybridization indicated a constitutional partial trisomy 8 mosaic (cT8M) in both patients. A survey on 27 cT8M patients with reported malignancies showed a predominance of myeloid malignancies including JMML. Our results dramatically reduce the critical region on chromosome 8 to 8p11.21q11.21. To determine how constitutional partial trisomy 8 mosaicisms may contribute to leukemogenesis in different mutational subtypes of JMML and other myeloid malignancies, further investigations are required.  相似文献   
28.
29.
Domestic dogs exhibit an extraordinary degree of morphological diversity. Such breed-to-breed variability applies equally to the canine skull, however little is known about whether this translates to systematic differences in cerebral organization. By looking at the paramedian sagittal magnetic resonance image slice of canine brains across a range of animals with different skull shapes (N = 13), we found that the relative reduction in skull length compared to width (measured by Cephalic Index) was significantly correlated to a progressive ventral pitching of the primary longitudinal brain axis (r = 0.83), as well as with a ventral shift in the position of the olfactory lobe (r = 0.81). Furthermore, these findings were independent of estimated brain size or body weight. Since brachycephaly has arisen from generations of highly selective breeding, this study suggests that the remarkable diversity in domesticated dogs'' body shape and size appears to also have led to human-induced adaptations in the organization of the canine brain.  相似文献   
30.
Joubert syndrome generally represents an autosomal recessive and rarely X-linked disorder characterized by hypotonia, an irregular breathing pattern, abnormal eye movements, ataxia, developmental delay and a complex mid-hindbrain malformation causing the molar tooth sign on magnetic resonance imaging (MRI). Many patients have additional features, with nephronophthisis, retinal dystrophy, coloboma and hepatic fibrosis representing the most frequent features. Due to its clinical variability and overlap with other syndromes, the term “Joubert syndrome and related disorders” (JSRD) was proposed. To date 10 genes are known to cause JSRD. The encoded proteins are localized to cilia, linking JSRD to other human ciliopathies.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号