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   181篇
  免费   25篇
  206篇
  2023年   4篇
  2022年   6篇
  2021年   6篇
  2020年   7篇
  2019年   4篇
  2018年   7篇
  2017年   6篇
  2016年   5篇
  2015年   13篇
  2014年   8篇
  2013年   10篇
  2012年   11篇
  2011年   14篇
  2010年   7篇
  2009年   6篇
  2008年   6篇
  2007年   4篇
  2006年   6篇
  2005年   10篇
  2004年   7篇
  2003年   7篇
  2002年   5篇
  2001年   5篇
  1999年   2篇
  1997年   2篇
  1990年   1篇
  1989年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1980年   3篇
  1979年   1篇
  1978年   2篇
  1977年   1篇
  1975年   2篇
  1974年   1篇
  1972年   2篇
  1970年   1篇
  1968年   2篇
  1967年   1篇
  1964年   2篇
  1963年   1篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   1篇
  1958年   1篇
  1955年   1篇
排序方式: 共有206条查询结果,搜索用时 0 毫秒
111.
Free radicals are implicated in many diseases including atherosclerosis, cancer and also in rheumatoid arthritis. Reaction of uric acid with free radicals, such as hydroxyl radical and hypochlorous acid (HOCl) results in allantoin production. In this study, we measured the serum allantoin levels, oxidation products of uric acid, as a marker of free radical generation in rheumatoid arthritis. Fasting blood samples were obtained from 21 rheumatoid patients and 15 healthy controls. In this study, the serum allantoin and uric acid levels were measured by a gas chromatography-mass spectrometry method and the ratios were calculated. The mean allantoin and uric acid levels and ratios in the patient group were 22.1±11.3, 280.5±65.0 and 8.0±3.7 μM, while in the control group they were 13.6±6.3, 278.3±53.6 and 4.9±2.1 μM, respectively. The effects of gender, age, menopausal status, duration of disease and medications on serum allantoin and uric acid levels of the patient and control groups were studied. Our results suggest that uric acid acts as a free radical scavenger and thus is converted to allantoin. Increased allantoin levels suggest the possible involvement of free radicals in rheumatoid arthritis.  相似文献   
112.
The experiment was conducted to study the effects of supplementing a broiler starter diet with the probiotic Enterococcus faecium NCIMB 10415 and dried whey (80% lactose) on chick performance, gut histomorphology and intestinal microbiota. One-day-old male Ross 308 strain broiler chickens were fed diets containing: (i) control feed, (ii) control + 3.5% dried whey, (iii) control + 0.2% E. faecium, and (iv) control + 3.5% dried whey + 0.2% E. faecium. Birds were maintained in battery brooders confined in an environmentally controlled experimental room. The experiment lasted for 21 days. Birds fed E. faecium or E. faecium + dried whey exhibited significantly improved weight gain and feed conversion rate (FCR). Weight gain and FCR of treatment groups 1-4 were 628.7, 657.8, 690.9, 689.3 and 1.218, 1.193, 1.107, 1.116, respectively. Lactic acid bacteria counts in both the ileal content and excreta were significantly affected by dietary treatment. Supplementation of the E. faecium and dried whey separately and in combination increased lactic acid bacteria colonization in the ileal content from 4.2 to 5.0, 7.8 and to 5.1 log cfu/g, respectively (treatments 1-4). Similarly, supplementation of dried whey and E. faecium separately and in combination increased lactic acid bacteria in the excreta from 5.3 to 5.5, 8.0 and to 7.2 log cfu/g, respectively. Addition of the probiotic E. faecium increased villus height in the ileum (p < 0.05). Thus, supplementation of E. faecium enhanced broiler chick performance with respect to weight gain and FCR. No additive effect of E. faecium and dried whey was detected. Further studies are needed to investigate the relationship between E. faecium and dried whey with respect to gut histomorphology.  相似文献   
113.
Biological Trace Element Research - Approximately 350–400 million people in the world have Hbs Ag (hepatitis B virus surface antigen) positivity. In the international guidelines, the...  相似文献   
114.
Marine traffic is a significant source of disturbance to the bottlenose dolphin population in the Istanbul Strait, Turkey. To determine the importance of this threat, behavioral data together with sighting data of both dolphins and marine vessels were assessed for 2012. The current study suggests that the Istanbul Strait is used mostly as a foraging ground for bottlenose dolphins. Nonetheless, in the same area there is intense marine traffic as well as increase of industrial fishing activities in autumn. The findings of this study indicated that high‐speed ferries and high‐speed boats were the most significant source of disturbance. Moreover, increased densities of fishing vessels resulted in a drastic decline of dolphin sightings. This study highlights that vessel type, speed, distance, and density have a cumulative negative effect on dolphins. In order to mitigate the impacts of vessels, it is necessary to establish managed areas in the Istanbul Strait. Such proposed areas should limit speed and density of marine traffic and have specific restrictions on vessel routes. We propose three different seasonal managed areas according to their values as critical habitat for bottlenose dolphins in the strait.  相似文献   
115.
This study compared the activity of commercial liquid sterilants and disinfectants on Bacillus subtilis spores deposited on three types of devices made of noncorrodible, corrodible, or polymeric material. Products like Renalin, Exspor, Wavicide-01, Cidexplus, and cupric ascorbate were tested under conditions specified for liquid sterilization. These products, at the shorter times indicated for disinfection, and popular disinfectants, like Clorox, Cavicide, and Lysol were also studied. Data obtained with a sensitive and quantitative test suggest that commercial liquid sterilants and disinfectants are less effective on contaminated surfaces than generally acknowledged.  相似文献   
116.
The linear ubiquitin chain assembly complex (LUBAC) is a RING E3 ligase that regulates immune and inflammatory signalling pathways. Unlike classical RING E3 ligases, LUBAC determines the type of ubiquitin chain being formed, an activity normally associated with the E2 enzyme. We show that the RING-in-between-RING (RBR)-containing region of HOIP-the catalytic subunit of LUBAC-is sufficient to generate linear ubiquitin chains. However, this activity is inhibited by the N-terminal portion of the molecule, an inhibition that is released upon complex formation with HOIL-1L or SHARPIN. Furthermore, we demonstrate that HOIP transfers ubiquitin to the substrate through a thioester intermediate formed by a conserved cysteine in the RING2 domain, supporting the notion that RBR ligases act as RING/HECT hybrids.  相似文献   
117.
Rapid increases in human populations provide a great challenge to ensure that adequate quantities of food are available. Sustainable development of agricultural production by breeding more productive cultivars and by increasing the productive potential of existing cultivars can help meet this demand. The present paper provides information on the potential uses of cryogenic techniques in ensuring food security, including: (1) long-term conservation of a diverse germplasm and successful establishment of cryo-banks; (2) maintenance of the regenerative ability of embryogenic tissues that are frequently the target for genetic transformation; (3) enhancement of genetic transformation and plant regeneration of transformed cells, and safe, long-term conservation for transgenic materials; (4) production and maintenance of viable protoplasts for transformation and somatic hybridization; and (5) efficient production of pathogen-free plants. These roles demonstrate that cryogenic technologies offer opportunities to ensure food security.  相似文献   
118.
Evolutionary conservation is a fundamental resource for predicting the substitutability of amino acids and the loss of function in proteins. The use of multiple sequence alignment alone—without considering the evolutionary relationships among sequences—results in the redundant counting of evolutionarily related alteration events, as if they were independent. Here, we propose a new method, PHACT, that predicts the pathogenicity of missense mutations directly from the phylogenetic tree of proteins. PHACT travels through the nodes of the phylogenetic tree and evaluates the deleteriousness of a substitution based on the probability differences of ancestral amino acids between neighboring nodes in the tree. Moreover, PHACT assigns weights to each node in the tree based on their distance to the query organism. For each potential amino acid substitution, the algorithm generates a score that is used to calculate the effect of substitution on protein function. To analyze the predictive performance of PHACT, we performed various experiments over the subsets of two datasets that include 3,023 proteins and 61,662 variants in total. The experiments demonstrated that our method outperformed the widely used pathogenicity prediction tools (i.e., SIFT and PolyPhen-2) and achieved a better predictive performance than other conventional statistical approaches presented in dbNSFP. The PHACT source code is available at https://github.com/CompGenomeLab/PHACT.  相似文献   
119.
The tomato as both a fresh consumption and industrial product is one of the most profitable vegetables and has a large cultivation area in the world. Parallel to intense production activities, Tomato Spotted Wilt Virus (TSWV), like viral diseases, results in significant economic losses every year. Use of resistant cultivars is the most efficient and environmental-friendly method of fighting against these diseases. This study was conducted to develop new tomato genetic resources resistant to TSWV because of the Sw-5 resistance breaking (RB) isolates that were determined in tomato cultivation areas. In this study, a total of 40 tomato materials including 15 lines, 9 commercial varieties and 16 wild genotypes were by tested with molecular and biological testing methods. Mechanical inoculation method was used for biological testing and SCAR marker was used in molecular analysis. S. penellii, S. chmielewski, S. habrochaites, S. peruvianum and S. sitiens, LA0716, LA1028, LA1777, LA2744 and LA4110 genotypes were found as resistant against breaking isolates of Tomato Spotted Wilt Virus. These genotypes may be a good resistance source for the future breeding studies in tomato.  相似文献   
120.
Mycopathologia - Dermatophytes are among the most successful fungal pathogens in humans, but their virulence mechanisms have not yet been fully characterized. Dermatophytic fungi secrete proteases...  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