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   1073篇
  免费   88篇
  2023年   1篇
  2022年   13篇
  2021年   22篇
  2020年   13篇
  2019年   15篇
  2018年   23篇
  2017年   32篇
  2016年   42篇
  2015年   50篇
  2014年   48篇
  2013年   93篇
  2012年   93篇
  2011年   101篇
  2010年   41篇
  2009年   45篇
  2008年   73篇
  2007年   69篇
  2006年   48篇
  2005年   64篇
  2004年   50篇
  2003年   49篇
  2002年   29篇
  2001年   12篇
  2000年   5篇
  1999年   11篇
  1998年   18篇
  1997年   13篇
  1996年   12篇
  1995年   9篇
  1994年   6篇
  1993年   8篇
  1992年   4篇
  1991年   3篇
  1990年   3篇
  1989年   6篇
  1988年   2篇
  1987年   4篇
  1986年   3篇
  1985年   4篇
  1983年   3篇
  1982年   3篇
  1981年   3篇
  1980年   4篇
  1979年   5篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
  1964年   2篇
  1958年   1篇
排序方式: 共有1161条查询结果,搜索用时 15 毫秒
11.
rG-CSF reduces endotoxemia and improves survival during E.coli pneumonia   总被引:2,自引:0,他引:2  
Freeman, Bradley D., Zenaide Quezado, Fabrice Zeni, CharlesNatanson, Robert L. Danner, Steven Banks, Marcello Quezado, YvonneFitz, John Bacher, and Peter Q. Eichacker. rG-CSF reduces endotoxemia and improves survival during E. coli pneumonia. J. Appl.Physiol. 83(5): 1467-1475, 1997.We investigatedthe effects of recombinant granulocyte colony-stimulating factor(rG-CSF) during canine bacterial pneumonia. Beagles with chronictracheostomies received daily subcutaneous rG-CSF (5 µg/kg body wt)or placebo for 14 days, beginning 9 days before intrabronchialinoculation with E. coli. Animalsreceived antibiotics and fluid support; a subset received humidifiedoxygen (fractional inspired O20.40). Compared with controls, rG-CSF increased circulating neutrophil counts (57.4 vs. 11.0 × 103/mm3,day 1 after infection;P = 0.0001), decreased plasmaendotoxin (7.5 vs. 1.1 EU/ml at 8 h; P < 0.01) and serum tumor necrosis factor- (3,402 vs.729 pg/ml at 2 h; P = 0.01) levels,and prolonged survival (relative risk of death = 0.45, 95% confidenceinterval 0.21-0.97; P = 0.038).Also, rG-CSF attenuated sepsis-associated myocardial dysfunction(P < 0.001). rG-CSF had no effect onpulmonary function or on blood and lung bacteria counts (allP = not significant). Other animalschallenged with endotoxin (4 mg/kg iv) after similar treatment withrG-CSF had lower serum endotoxin levels (7.62 vs. 5.81 log EU/ml at 6 h; P < 0.01) and less cardiovasculardysfunction (P < 0.05 to < 0.002)but similar tumor necrosis factor- levels (P = not significant) compared withcontrols. Thus prophylactic rG-CSF sufficient to increase circulatingneutrophils during bacterial pneumonia may improve cardiovascularfunction and survival by mechanisms that in part enhance the clearanceof bacterial toxins but do not improve lung function.

  相似文献   
12.
We previously reported that the 7 alpha-dehydroxylation of cholic acid appears to be carried out by a multi-step pathway in intestinal anaerobic bacteria both in vitro and in vivo. The pathway is hypothesized to involve an initial oxidation of the 3 alpha-hydroxy group and the introduction of a double bond at C4-C5 generating a 3-oxo-4-cholenoic bile acid intermediate. The loss of water generates a 3-oxo-4,6-choldienoic bile acid which is reduced (three steps) yielding deoxycholic acid. We synthesized, in radiolabel, the following putative bile acid intermediates of this pathway 7 alpha,12 alpha-dihydroxy-3-oxo-4-cholenoic acid, 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholanoic acid, 12 alpha-dihydroxy-3-oxo-4,6-choldienoic acid, and 12 alpha-hydroxy-3-oxo-4-cholenoic acid and showed that they could be converted to 3 alpha,12 alpha-dihydroxy-5 beta-cholanoic acid (deoxycholic acid) by whole cells or cell extracts of Eubacterium sp. VPI 12708. During studies of this pathway, we discovered the accumulation of two unidentified bile acid intermediates formed from cholic acid. These bile acids were purified by thin-layer chromatography and identified by gas-liquid chromatography-mass spectrometry as 12 alpha-hydroxy-3-oxo-5 alpha-cholanoic acid and 3 alpha,12 alpha-dihydroxy-5 alpha-cholanoic (allo-deoxycholic acid). Allo-deoxycholic acid was formed only in cell extracts prepared from bacteria induced by cholic acid, suggesting that their formation may be a branch of the cholic acid 7 alpha-dehydroxylation pathway in this bacterium.  相似文献   
13.
A new method for peptide analysis and purification is described, based on isoelectric focusing in immobilized pH gradients. On the analytical scale, the peptide zones can now be revealed by an stain for primary and secondary amino group (e.g. ninydrin, fluorescamine, dansyl chloride) since the buffering species, unlike conventional carrier ampholytes, contain only carboxyl and tertiary amino groups. For preparative purposes, conditions have been described to remove most contaminants (e.g. unreacted monomers, non-cross-linked, short polyacrylamide chains) from the gel matrix before the electrophoretic run. However, ca. 2% of the gel dry mass is still present as extractable material. The focused peptides can be recovered in higly yields (ca. 90%) with a fairly high degree of purity (75%), the contaminants being mostly components eluted from the polyacrylamide gel.  相似文献   
14.
The development of drugs able to target BTK, PI3k‐delta and BCL2 has dramatically improved chronic lymphocytic leukaemia (CLL) therapies. However, drug resistance to these therapies has already been reported due to non‐recurrent changes in oncogenic pathways and genes expression signatures. In this study, we investigated the cooperative role of the BCL2 inhibitor venetoclax and the BRD4 inhibitor JQ1. In particular, we found that JQ1 shows additional activity with venetoclax, in CLL cell lines and in ex vivo isolated primary CD19+ lymphocytes, arguing in favour of combination strategies. Lastly, JQ1 is also effective in venetoclax‐resistant CLL cell lines. Together, our findings indicated that the BET inhibitor JQ1 could be a promising therapy in CLL, both as first‐line therapy in combination with venetoclax and as second‐line therapy, after the emergence of venetoclax‐resistant clones.  相似文献   
15.
Effective seed storage after sourcing (harvesting or purchasing) is critical to restoration practitioners and native seed producers, as it is key to maintaining seed viability. Inadequate seed storage can lead to a waste of both natural and economic resources when seeds of poor quality are sown. When working with native species with unknown storage behavior, general assumptions can be made based on studies on related species, and standard practices may be applied with caution; however, an investigation should be conducted to understand if specific storage requirements are needed and for how long seeds can be stored before they lose significant viability. In this paper of the Special Issue Standards for Native Seeds in Ecological Restoration, we provide an overview of the key concepts in seed storage and the steps to take for effective storage of native seeds for restoration use.  相似文献   
16.
Molecular Biology Reports - Benign metastasizing leiomyoma (BML) is a rare disease characterized by extrauterine benign leiomyomatosis in patients with a previous or concomitant history of uterine...  相似文献   
17.
18.
19.

The genus Dorema (Apiaceae) comprises 12 accepted species, mainly growing in Asia and, particularly, in Iran, where D. ammoniacum and D. aucheri are the most used species in cuisine and folk medicine. The Dorema species are traditionally applied in the treatment of catarrh, asthma, chronic bronchitis, as carminative, mild diuretic and anthelmintic agents. In general, 42 non-volatile secondary metabolites were isolated from the 6 studied species, namely D. aitchisonii, D. ammoniacum, D. aucheri, D. glabrum, D. hyrcanum, and D. kopetdaghense. Among them, phenolic acid, flavonoid, acetophenone, coumarin, and sesquiterpene derivatives were identified as the predominant phytoconstituents. The leaves are characterized by the highest volatile content, and the sesquiterpenes in both hydrocarbon and oxygenated forms were reported as the most abundant compounds. Most of the studied pharmacological activities were assessed in vivo. Nevertheless, in vitro antiradical and antimicrobial potentials were the main investigated activities. Overall, the evaluation of bioactivities confirmed the ethnopharmacological use of the Dorema species, particularly their anti-inflammatory, antibacterial, and hypolipidemic properties. This study comprehensively overviewed, for the first time, the literature relating to the folk medicinal use and to the available phytochemical and pharmacological data. Considering the genus application and the rare clinical trials, the study of the efficacy and safety of the uninvestigated Dorema species might be an interesting and promising approach for further researches.

  相似文献   
20.
Abstract

From March 1988 to April 1989 a survey was carried out on the phytoplankton of Lake Bidighinzu, a hypertrophic reservoir in Northern Sardinia. The purpose of this work was to assess the general limnological conditions of the reservoir after a diversion of the urban and industrial wastes. The dynamics of chlorophyll a, and the structure and composition of the phytoplankton density and of its biomass in the study period were determined. Moreover the found trends for trasparency, temperature, conductivity, alkalinity, pH, dissolved oxygen, reactive and total phosphorus, nitrate, nitrite, ammonium nitrogen, and reactive silica are reported. The effect of water aeration on the dynamics of the other parameters is discussed.  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