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   503篇
  免费   30篇
  国内免费   1篇
  2023年   1篇
  2022年   8篇
  2021年   20篇
  2020年   8篇
  2019年   7篇
  2018年   4篇
  2017年   8篇
  2016年   21篇
  2015年   37篇
  2014年   31篇
  2013年   33篇
  2012年   36篇
  2011年   39篇
  2010年   34篇
  2009年   26篇
  2008年   32篇
  2007年   35篇
  2006年   29篇
  2005年   28篇
  2004年   16篇
  2003年   19篇
  2002年   15篇
  2001年   2篇
  1999年   2篇
  1998年   3篇
  1996年   3篇
  1994年   4篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1987年   1篇
  1986年   5篇
  1981年   3篇
  1979年   1篇
  1978年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1969年   1篇
  1966年   1篇
  1963年   1篇
  1962年   3篇
  1961年   1篇
  1960年   2篇
  1952年   1篇
  1947年   1篇
  1926年   1篇
排序方式: 共有534条查询结果,搜索用时 62 毫秒
11.
12.
13.
14.
15.
Tribolium confusum is a major pest of grains and grain products. Some legumes hitherto not used as major food are gaining interest due to increase in human population and the need of food and feeds. Susceptibility of fresh and processed Glycine max and Cajanus cajan flours, and white wheat flour (control) to T. confusum was studied towards effective storage techniques and cheap insect diet. Ten copulating pairs of the beetle were introduced into twenty grams of each flour. Number of eggs laid, emerged larvae, pupae, eclosed adults, and duration of development of each stage was used as indices of survival of T. confusum. Proximate composition, saponin; and α-amylase and protease inhibitors determined suitability of flours as insect diet. This work discusses the significance of proximate composition and anti-nutrient properties in fresh and roasted processed flours on the development and survival of T. confusum.  相似文献   
16.
Abstract Comparisons of growth and surface colonisation of Enterococcus faecium L-forms and their cell-walled forms were undertaken to produce information about their ability to form sessile cells. The growth of L-forms in liquid culture was slower than that of the parent. This was reflected in their longer lag phase and slower specific growth rates: 0.16 h−1 for the L-form and 0.81 h−1 for the parent. Although E. faecium L-forms attached to a silastic rubber surface, the attached population density was 10–100-fold less than that of the parent. Confluent biofilms on the silastic surfaces were not observed for either bacterial form. Comparison of the attachment of E. faecium L-form and parent may provide important information on how bacteria overcome host defence mechanisms and antibiotic treatment.  相似文献   
17.
Background:Previous studies have found that race is associated with emergency department triage scores, raising concerns about potential health care inequity. As part of a project on quality of care for First Nations people in Alberta, we sought to understand the relation between First Nations status and triage scores.Methods:We conducted a population-based retrospective cohort study of health administrative data from April 2012 to March 2017 to evaluate acuity of triage scores, categorized as a binary outcome of higher or lower acuity score. We developed multivariable multilevel logistic mixed-effects regression models using the levels of emergency department visit, patient (for patients with multiple visits) and facility. We further evaluated the triage of visits related to 5 disease categories and 5 specific diagnoses to better compare triage outcomes of First Nations and non–First Nations patients.Results:First Nations status was associated with lower odds of receiving higher acuity triage scores (odds ratio [OR] 0.93, 95% confidence interval [CI] 0.92–0.94) compared with non–First Nations patients in adjusted models. First Nations patients had lower odds of acute triage for all 5 disease categories and for 3 of 5 diagnoses, including long bone fractures (OR 0.82, 95% CI 0.76–0.88), acute upper respiratory infection (OR 0.90, 95% CI 0.84–0.98) and anxiety disorder (OR 0.67, 95% CI 0.60–0.74).Interpretation:First Nations status was associated with lower odds of higher acuity triage scores across a number of conditions and diagnoses. This may reflect systemic racism, stereotyping and potentially other factors that affected triage assessments.

Health outcomes are markedly worse for First Nations than non–First Nations people. Although this is largely because of inequities in the social determinants of health,14 inequities in the provision of health care also exist.5,6 Emergency departments serve as a point of accessible health care. Status First Nations patients make up 4.8% of unique patients and 9.4% of emergency visits in Alberta,7 and Canadian studies describe First Nations patients’ experiences with racism when seeking emergency care.8,9Evaluating triage contributes empirically to understanding the health care of First Nations patients insofar as triage is a quantifiable, intermediate process by which systemic racism10 may influence patient outcomes. The Canadian Triage Acuity Scale11 is a 5-level scale used to classify the severity of patient symptoms. Triage nurses use a brief assessment, medical history, and presenting signs and symptoms to assign each patient a triage score that determines the priority in which the patient should be seen by a provider. Therefore, accurate triage is important for patient health outcomes.12 In practice, triage is a social interaction where local practice, biases, stereotypes and communication barriers come into play. Studies have found that women receive less acute triage scores than men,13,14 and that racial minority13,1517 and Indigenous1820 patients receive less acute triage scores than white or non-Indigenous patients. Indeed, Indigenous patients in Canada have described a perception “of social triaging in the [emergency department], whereby decisions about who is seen first seemed to them [to be] based less on triaged clinical priorities but on the social positioning of the patient.”21 Differential triage scores for minority populations raise health equity concerns.As part of a larger mixed-methods project evaluating the quality of emergency care for First Nations people in Alberta, we sought to evaluate quantitative differences in emergency visit characteristics and outcomes of First Nations and non–First Nations people in Alberta. Specifically, we aimed to estimate the relation between First Nations status and acuity of triage, and to evaluate whether predictors of acuity differ by First Nations status.  相似文献   
18.
Urotensin II and its receptor are coexpressed in the heart and up-regulated during cardiac dysfunction. In cultured neonatal cardiomyocytes, we mimicked this up-regulation using an adenovirus to increase expression of the urotensin receptor. In this model system, urotensin II promoted strong hypertrophic growth and phenotypic changes, including cell enlargement and sarcomere reorganization. Urotensin II potently activated the MAPKs, ERK1/2 and p38, and blocking these kinases with PD098059 and SB230580, respectively, significantly inhibited urotensin II-mediated hypertrophy. In contrast, urotensin II did not activate JNK. The activation of ERK1/2 and p38 as well as cellular hypertrophy was independent of protein kinase C, and calcium and phosphoinositide 3-kinase, yet dependent on the capacity of the urotensin receptor to trans-activate the epidermal growth factor receptor. Urotensin II promoted the tyrosine phosphorylation of epidermal growth factor receptors, which was inhibited by the selective epidermal growth factor receptor kinase inhibitor, AG1478. These data indicate that perturbations in cardiac homeostasis, which lead to up-regulation of urotensin II receptors, promote urotensin II-mediated cardiomyocyte hypertrophy via ERK1/2 and p38 signaling pathways in an epidermal growth factor receptor-dependent manner.  相似文献   
19.
The phlebotomine sand flies Nyssomyia intermedia (Lutz & Neiva, 1912) and Nyssomyia neivai (Pinto, 1926) are very close and may be involved in the transmission of Leishmania spp. Ross, 1903 in Brazil. The biology of the first laboratory-reared generations of these species, descended from insects captured in Além Paraíba (N. intermedia) and Corinto (N. neivai) in the Brazilian state of Minas Gerais, is described here. The captured females were fed on hamsters and maintained individually in rearing pots. Laboratory temperature and relative humidity were maintained at 25-26 masculineC and 80% respectively. The productivity of the first generation of N. intermedia was greater than that of N. neivai, and its development time clearly shorter, particularly for the second and third larval instars.  相似文献   
20.
Abstract In newly invaded communities, interspecific competition is thought to play an important role in determining the success of the invader and its impact on the native community. In southern Australia, the native Polistes humilis was the predominant social wasp prior to the arrival of the exotic Vespula germanica (Hymenoptera: Vespidae). Both species forage for similar resources (water, pulp, carbohydrate and protein prey), and concerns have arisen about potential competition between them. The aim of this study was to identify the protein foods that these wasps feed on. As many prey items are masticated by these wasps to the degree that they cannot be identified using conventional means, morphological identification was complemented by sequencing fragments of the mitochondrial 16S rRNA gene. GenBank searches using blast and phylogenetic analyses were used to identify prey items to at least order level. The results were used to construct complete prey inventories for the two species. These indicate that while P. humilis is restricted to feeding on lepidopteran larvae, V. germanica collects a variety of prey of invertebrate and vertebrate origin. Calculated values of prey overlap between the two species are used to discuss the implications of V. germanica impacting on P. humilis. Results obtained are compared to those gained by solely 'conventional' methods, and the advantages of using DNA-based taxonomy in ecological studies are emphasized.  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