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   449篇
  免费   26篇
  475篇
  2023年   1篇
  2022年   2篇
  2021年   6篇
  2020年   3篇
  2019年   6篇
  2018年   12篇
  2017年   10篇
  2016年   21篇
  2015年   23篇
  2014年   27篇
  2013年   43篇
  2012年   45篇
  2011年   47篇
  2010年   21篇
  2009年   20篇
  2008年   28篇
  2007年   29篇
  2006年   21篇
  2005年   18篇
  2004年   17篇
  2003年   12篇
  2002年   20篇
  2001年   6篇
  2000年   5篇
  1999年   4篇
  1998年   1篇
  1997年   6篇
  1995年   1篇
  1994年   1篇
  1993年   5篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   2篇
  1987年   4篇
  1986年   1篇
  1983年   1篇
  1975年   1篇
排序方式: 共有475条查询结果,搜索用时 15 毫秒
31.
32.
33.
Following our previous research on anti-inflammatory drugs (NSAIDs), we report here the synthesis of chiral 1,5-diarylpyrroles derivatives that were characterized for their in vitro inhibitory effects toward cyclooxygenase (COX) isozymes. Analysis of enzymatic affinity and COX-2 selectivity led us to the selection of one compound (+/-)-10b that was further tested in vitro in the human whole blood (HWB) and in vivo for its anti-inflammatory activity in mice. The affinity data have been rationalized through docking simulations.  相似文献   
34.
Endocrine disruptors are chemicals able to induce adverse effects into wildlife and humans owing to their ability of interfering with the endocrine system. Bisphenol A (BPA) has been chosen as model of endocrine disruptors. To reduce the BPA pollution in waters we proposed the employment of the process of thermodialysis. Two different catalytic membranes have been prepared by covalently immobilizing laccase (from Trametes versicolor) by means of a diazotation process or tyrosinase (from mushroom) by condensation. The support was a nylon membrane. The bioremediation power of both catalytic membranes has been analysed under isothermal and non-isothermal conditions.The advantages in using non-isothermal bioreactors were discussed in terms of reduction of the bioremediation times.  相似文献   
35.
This article documents the addition of 92 microsatellite marker loci to the Molecular Ecology Resources Database. Loci were developed for the following species: Anopheles minimus, An. sinensis, An. dirus, Calephelis mutica, Lutjanus kasmira, Murella muralis and Orchestia montagui. These loci were cross-tested on the following species: Calephelis arizonensi, Calephelis borealis, Calephelis nemesis, Calephelis virginiensis and Lutjanus bengalensis.  相似文献   
36.
Summary Utilizing phage display peptide libraries, we have identified and mapped the antigenic determinants recognized by mouse monoclonal antibodies (mAb) on two sets of immunologically important molecules, HLA class I and class II antigens. Anti-HLA class I mAb TP25.99 recognizes a conformational and a linear determinant on distinct regions of the HLA class I α3 domain. Anti-HLA class I mAb HO-4 recognizes a conformational determinant on the α2 domain of HLA-A2 and A28 allospecificities. Anti-HLA-DR1,-DR4,-DR6,-DR8,-DR9 mAb SM/549 recognizes a conformational determinant on the β chain of HLA class II antigens. These results indicate the versatility of phage display peptide libraries to characterize antigenic determinants recognized by anti-HLA mAb.  相似文献   
37.

Background

In Brazil, case-fatality rates attributable to visceral leishmaniasis (VL) are high and knowledge of the risk factors associated with death may help reduce mortality. The aim of this study was to construct and validate a scoring system for prognosis of death from VL by using all cases reported in Brazil from 2007 to 2011.

Methodology

In this historical cohort study, 18,501 VL cases were analyzed; of these, 17,345 cases were cured and 1,156 cases caused death. The database was divided into two series: primary (two-thirds of cases), to develop the model score, and secondary (one-third of cases), to validate the scoring system. Multivariate logistic regression models were performed to identify factors associated with death from VL, and these were included in the scoring system.

Principal Findings

The factors associated with death from VL were: bleeding (score 3); splenomegaly (score 1); edema (score 1); weakness (score 1); jaundice (score 1); Leishmania–HIV co-infection (score 1); bacterial infection (score 1); and age (≤0.5 years [score 5]; >0.5 and ≤1 [score 2]; >19 and ≤50 [score 2]; >50 and <65 [score 3]; ≥65 [score 5]). It was observed that patients with a score of 4 had a probability of death of approximately 4.5% and had a worse prognosis. The sensitivity, specificity, and accuracy of this score were 89.4, 51.2, and 53.5, respectively.

Conclusions/Significance

The scoring system based on risk factors for death showed good performance in identifying patients with signs of severity at the time of clinical suspicion of VL and can contribute to improving the surveillance system for reducing case fatalities. The classification of patients according to their prognosis for death may assist decision-making regarding the transfer of the patients to hospitals more capable of handling their condition, admission to the intensive care unit, and adequate support and specific treatment.  相似文献   
38.
Biodiversity of diazotrophic symbiotic bacteria in the tropics is a valuable but still poorly studied resource. The objective of this study was to determine if a second housekeeping gene, glnII, in addition to the 16S rRNA, can be employed to improve the knowledge about taxonomy and phylogeny of rhizobia. Twenty-three elite rhizobial strains, very effective in fixing nitrogen with twenty-one herbal and woody legumes (including species from fourteen tribes in the three subfamilies of the family Leguminosae) were selected for this study; all strains are used as commercial inoculants in Brazil. Complete sequences of the 16S rRNA and partial sequences (480 bp) of the glnII gene were obtained. The same primers and amplification conditions were successful for sequencing the glnII genes of bacteria belonging to five different rhizobial genera—Bradyrhizobium, Mesorhizobium, Methylobacterium, Rhizobium, Sinorhizobium)—positioned in distantly related branches. The analysis of the concatenated genes (16S rRNA + glnII) considerably improved information about phylogeny and taxonomy of rhizobia in comparison to the single analysis of the 16S rRNA. Nine strains might belong to new species. The complementary analysis of the glnII gene was successful with all strains and improved the phylogenetic clustering and clarified the taxonomic position of several strains. The strategy of including the analysis of glnII, in addition to the 16S rRNA, is cost- and time- effective for the characterization of large rhizobial culture collections or in surveys of many isolates.  相似文献   
39.
40.
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