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   145篇
  免费   15篇
  2021年   3篇
  2019年   3篇
  2018年   3篇
  2017年   2篇
  2016年   2篇
  2015年   5篇
  2014年   4篇
  2013年   11篇
  2012年   9篇
  2011年   5篇
  2010年   4篇
  2009年   5篇
  2008年   5篇
  2007年   6篇
  2006年   5篇
  2004年   4篇
  2003年   3篇
  2002年   5篇
  2001年   4篇
  2000年   2篇
  1995年   2篇
  1992年   2篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1978年   2篇
  1977年   4篇
  1976年   2篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1972年   4篇
  1971年   3篇
  1970年   6篇
  1969年   3篇
  1968年   4篇
  1967年   3篇
  1966年   2篇
  1965年   3篇
  1963年   1篇
  1961年   2篇
  1956年   1篇
  1954年   1篇
  1947年   1篇
  1934年   1篇
排序方式: 共有160条查询结果,搜索用时 15 毫秒
1.
Fungal spores are an important component of library air   总被引:4,自引:0,他引:4  
The airborne fungal spore types were studied in different libraries in Delhi, using an Andersen sampler and a Burkard personal sampler, for culturable and non-culturable fungi respectively. The concentration inside the libraries, before and after the agitation of books, were compared with outside air. The major contributors to the library air areCladosporium, aspergilli/penicillia, smuts andAlternaria, varying from 50 to 14%. Some fungi (Cladosporium, Alternaria, smut,Penicillium chrysogenum andnigricans) showed seasonal occurrence, corresponding to their occurrence in the extramural environment. Aspergilli/penicillia,Drechslera, Curvularia andAspergillus flavus had a significantly higher concentration (P<0.01) inside the library, and recorded a significant increase in concentration after agitation of books. Air-conditioned libraries have low fungal spore concentrations, as compared to naturally ventilated libraries.  相似文献   
2.
Two different vaginal suppositories have been developed suitable for one single treatment for preoperative dilatation of the cervix prior to vacuum aspiration in late first trimester abortion. The study included 60 patients equally distributed in one control group (Group I) where vacuum aspiration was performed without pretreatment; one group (Group II) where the patients obtained 2.0 mg 15-methyl-PGF-methyl ester in a rapid releasing base six hours prior to operation and one group (Group III) where the prostaglandin dose was increased to 2.5 mg 15-methyl-PGF-methyl ester and a more slow releasing base was used and the operation performed after 12 hours. The mean cervical dilatation at operation was in Group II 9 mm and in Group III 11 mm in comparison with 4.8 mm in the control group. The bleeding at the operation was also significantly reduced.  相似文献   
3.
This study evaluated the ability of a rapid identification system for anaerobic bacteria, ATB 32A, now renamed RAPID ID 32A (API-bioMérieux UK Ltd., Basingstoke), to identify accurately 74 strains of the 'B. fragilis group'. ATB 32A identified correctly 78.4% of strains to species level, without supplemental tests. The percentage of strains identified to species level rose to 94.6% when a supplementary test (advised by bioMérieux) for catalase production was used to differentiate between Bacteroides ovatus and Bacteroides uniformis. RAPID ID 32A is a rapid, accurate method for the identification of members of the 'B. fragilis group' isolated within a routine clinical laboratory.  相似文献   
4.
5.
Smokeless tobacco usage is a growing public health problem worldwide. The molecular mechanism(s) underlying smokeless tobacco associated tissue damage remain largely unidentified. In the present study we have tried to explore the effects of aqueous extract of smokeless tobacco (STE) on tubulin-microtubule, the major cytoskeleton protein that maintains cells morphology and participates in cell division. Exposure to STE resulted in dose-dependent cytotoxicity in a variety of mammalian transformed cell lines such as human lung epithelial cells A549, human liver epithelial cells HepG2, and mouse squamous epithelial cells HCC7, as well as non-tumorogenic human peripheral blood mononuclear cells PBMC. Cellular morphology of STE-treated cells was altered and the associated disruption of microtubule network indicates that STE targets tubulin-microtubule system in both cell lines. Furthermore it was also observed that STE-treatment resulted in the selective degradation of cellular tubulin, whereas actin remains unaltered. In vitro, polymerization of purified tubulin was inhibited by STE with the IC50 value∼150 µg/ml and this is associated with the loss of reactive cysteine residues of tubulin. Application of thiol-based antioxidant N-acetyl cysteine (NAC) significantly abrogates STE-mediated microtubule damage and associated cytotoxicity in both A549 and HepG2 cells. These results suggest that microtubule damage is one of the key mechanisms of STE-induced cytotoxity in mammalian cells.  相似文献   
6.
Lactobacillus casei LA‐1 isolated from a nondairy fermented source was evaluated for its in vitro ability to reduce cholesterol. The bacterium tested positive for bile salt deconjugation in relation to cholesterol removal. Tested growth‐associated physiological variables such as pH, temperature and inoculum size were all found to have significant effects on in vitro cholesterol reduction and biomass production (both P < 0.005). Furthermore, a central composite design was used to evaluate the effects of significant variables and their interactions. A linear regression model was developed for in vitro cholesterol reduction as a function of growth‐associated variables. Maximum cholesterol reduction achieved was 45% whereas maximum biomass yield of 2.34 optical density was observed at the central point. Our study possibly indicates that the growth of L. casei LA‐1 depends on its cholesterol removing ability.  相似文献   
7.
Batteries for high temperature applications capable of withstanding over 60 °C are still dominated by primary cells. Conventional rechargeable energy storage technologies which have exceptional performance at ambient temperatures employ volatile electrolytes and soft separators, resulting in catastrophic failure under heat. A composite electrolyte/separator is reported that holds the key to extend the capability of Li‐ion batteries to high temperatures. A stoichiometric mixture of hexagonal boron nitride, piperidinium‐based ionic liquid, and a lithium salt is formulated, with ionic conductivity reaching 3 mS cm?1, electrochemical stability up to 5 V and extended thermal stability. The composite is used in combination with conventional electrodes and demonstrates to be stable for over 600 cycles at 120 °C, with a total capacity fade of less than 3%. The ease of formulation along with superior thermal and electrochemical stability of this system extends the use of Li‐ion chemistries to applications beyond consumer electronics and electric vehicles.  相似文献   
8.
Intracellular kinases play important roles in signal transduction and are involved in the surface receptor-mediated regulation of cellular functions, including mitogenesis. In the present study, we examined the possible involvement of various protein kinases in the passage of a mitogenic signal from the cell surface to the nucleus of Nb2 cells, a rat nodal lymphoma cell line in which prolactin is a mitogen. Following a prolactin challenge, various kinase activities were monitored at short intervals in different cellular fractions over a 60 min period. Protein kinase C (PKC) activity in the cytosolic fraction rapidly declined to 50% of its original activity within the first 30 min, while PKC activity in the nuclear fractions increased sharply, reaching its highest level by 30 min following a prolactin challenge. There were also increases in both casein kinase and protein tyrosine kinase (PTK) activities in the nuclear fractions during the first 30 min following a prolactin challenge that paralleled PKC activity. The activities of all three kinases declined thereafter, reaching levels close to their respective basal values by 60 min following initiation of prolactin treatment. These observations suggest the possibility that multiple protein kinases may be involved in mitogenic signal transduction for prolactin in Nb2 cells. © 1996 Wiley-Liss, Inc.  相似文献   
9.
Allele frequencies are most often reported from small convenience samples of unknown demographics and limited generalizability. We determined the distribution of apolipoprotein E genotype (APOE) and allele frequencies for a large, well-defined, representative, rural, population-based sample (n = 4450) aged 55-95 years in Ballabgarh, in the northern Indian state of Haryana. The overall APOE E*2, E*3, and E*4 allele frequencies were 0.039, 0.887, and 0.073, respectively; frequencies are also reported by age, sex, and religious/caste groups. The APOE*4 frequency is among the lowest reported anywhere in the world. APOE allele frequencies did not vary significantly by age or sex in this study. To our knowledge, this is the largest Indian sample ever genotyped for the APOE polymorphism. The representativeness of the sample and its known demographics provide a much-needed normative background for studies of gene-disease associations.  相似文献   
10.
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