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   1101篇
  免费   151篇
  国内免费   38篇
  2024年   7篇
  2023年   23篇
  2022年   30篇
  2021年   31篇
  2020年   45篇
  2019年   41篇
  2018年   35篇
  2017年   29篇
  2016年   26篇
  2015年   34篇
  2014年   60篇
  2013年   76篇
  2012年   52篇
  2011年   68篇
  2010年   45篇
  2009年   55篇
  2008年   69篇
  2007年   53篇
  2006年   52篇
  2005年   57篇
  2004年   38篇
  2003年   33篇
  2002年   26篇
  2001年   14篇
  2000年   17篇
  1999年   24篇
  1998年   14篇
  1997年   14篇
  1996年   13篇
  1995年   14篇
  1994年   15篇
  1993年   17篇
  1992年   18篇
  1991年   12篇
  1990年   10篇
  1989年   8篇
  1988年   8篇
  1987年   4篇
  1986年   5篇
  1985年   9篇
  1984年   12篇
  1983年   9篇
  1982年   8篇
  1981年   16篇
  1980年   10篇
  1979年   11篇
  1978年   11篇
  1974年   4篇
  1973年   3篇
  1972年   2篇
排序方式: 共有1290条查询结果,搜索用时 15 毫秒
71.
72.
Early diagnosis is important for effective disease management. Measurement of biomarkers present at the local level of the skin could be advantageous in facilitating the diagnostic process. The analysis of the proteome of suction blister fluid, representative for the interstitial fluid of the skin, is therefore a desirable first step in the search for potential biomarkers involved in biological pathways of particular diseases. Here, we describe a global analysis of the suction blister fluid proteome as potential body fluid for biomarker proteins. The suction blister fluid proteome was compared with a serum proteome analyzed using identical protocols. By using stringent criteria allowing less than 1% false positive identifications, we were able to detect, using identical experimental conditions and amount of starting material, 401 proteins in suction blister fluid and 240 proteins in serum. As a major result of our analysis we construct a prejudiced list of 34 proteins, relatively highly and uniquely detected in suction blister fluid as compared to serum, with established and putative characteristics as biomarkers. We conclude that suction blister fluid might potentially serve as a good alternative biomarker body fluid for diseases that involve the skin.  相似文献   
73.
摘要 目的:探讨血清淀粉样蛋白A(SAA)、D-二聚体(D-D)、肌酸激酶同工酶(CK-MB)联合检测对川崎病患儿冠状动脉损伤(CAL)的诊断价值。方法:选取2018年9月~2021年5月我院收治的80例川崎病患儿,根据是否合并CAL分为CAL组(n=34)和NCAL组(n=46)。收集患儿基础资料,并检测SAA、D-D、CK-MB水平。多因素Logistic回归分析川崎病患儿CAL影响因素,受试者工作特征(ROC)曲线分析血清SAA、D-D、CK-MB水平对川崎病患儿CAL的诊断价值。结果:与NCAL组比较,CAL组C反应蛋白(CRP)、红细胞沉降率(ESR)、SAA、D-D、CK-MB水平升高(P<0.05)。多因素Logistic回归分析显示,CRP、ESR、SAA、D-D、CK-MB为川崎病患儿CAL独立影响因素(P<0.05)。SAA、D-D、CK-MB、三项联合诊断川崎病患儿CAL的曲线下面积(AUC)分别为0.661、0.687、0.746、0.799,联合应用的诊断效能最高。结论:血清SAA、D-D、CK-MB是川崎病患儿CAL独立影响因素,且联合检测以上指标可辅助诊断川崎病患儿CAL。  相似文献   
74.

Background

Mesenchymal stromal cells (MSCs) can be used in several clinical applications. While MSCs are frequently cultured in fetal bovine serum for in vitro experimentation, human serum supplements are required for cells to be used in patients. Here we show how different human serum supplements and in vitro manipulations used during the cell culture impact on MSC proliferation rate and expression of inflammatory molecules.

Methods

MSCs were cultured in medium supplemented with human plasma or serum combined with human platelet lysate (PL) and/or basic fibroblast growth factor (FGF2). Real time RT-PCR and western blot were used to assess expression of inflammatory cytokines.

Results

Serum with addition of FGF2 gave the fastest proliferation rate. However, serum with FGF2 also increased expression of genes encoding inflammatory cytokines. The most favorable expansion condition for chondrogenic differentiation and inhibition of cartilage matrix degrading enzymes was plasma supplemented with PL and FGF2. Detachment of cells using trypsin gave considerable upregulation of inflammatory cytokine mRNAs which lasted for up to 24?h, with concomitant increase in protein levels. Even the gentle act of changing medium led to upregulation of cytokine mRNA, caused by addition of fresh serum.

Discussion

Different culture conditions and simple cell manipulation influence proliferation rate and expression of inflammatory genes. Supplementing culture medium with allogeneic AB serum and FGF2 during monolayer expansion supported cell expansion better than other supplements, but also induced the highest levels of inflammatory cytokines and gave inferior results for chondrogenic differentiation. The importance of the composition of the culture medium and even gentle in vitro manipulation of the cells should be taken into account in the planning of procedures using in vitro expanded MSCs.  相似文献   
75.
In this study, a new lanthanum (III)-amino acid complex utilizing cysteine has been synthesized and characterized. The anticancer activities of the prepared La(III) complex against MCF-7 cell lines were studied. Results of MTT assay showed that at all three incubation times, the cytotoxic effect of prepared La(III) complex on MCF-7 breast cancer cell lines displays a time- and dose-dependent inhibitory effects. The interactions of the La(III) complex with two whey proteins (bovine serum albumin, BSA, and Bovine β-lactoglobulin, βLG) have been explored by using spectroscopic and molecular dicking methods. The obtained results indicated that La(III) complex strongly quenched the fluorescence of two carrier proteins in static quenching mode and also, BSA hah stronger binding affinity toward studied complex than βLG whit binding constant values of KBSA-La?Complex?~?0.11?×?104 M?1 and KβLG-La?Complex?~?0.63?×?103 M?1 at 300 K. The thermodynamic parameters revealed the contribution of hydrogen bond and Vander Waals interactions in both systems. The distances of the La(III) complex whit whey proteins were calculated using Förster energy transfer theory and proved existence of the energy transfer between two proteins and prepared La(III) complex with a high probability. FT-IR and UV–Vis absorption measurements indicated that the binding of the La(III) to BSA and βLG may induce conformational and micro-environmental changes of the proteins. The docking results indicate that the La(III) complex bind to residues located in the site II of BSA and second site of βLG.

Communicated by Ramaswamy H. Sarma  相似文献   

76.
Summary The role of serum albumin in the transport of orally administered L-tryptophan (Trp) into rat tissues was examined using analbuminemic and Sprague-Dawley (SD) rats with and without a-methyl-DL-tryptophan (AMT)-induced Trp depletion. Trp was orally administered to rats 16h after AMT or 0.85% NaCl administration, when liver tryptophan 2,3-dioxygenase and protein synthetic activities in AMT-treated rats were similar to those of 0.85% NaCl-treated rats. After oral Trp administration, regardless of the presence or absence of Trp depletion, free serum Trp concentrations were similar in the analbuminemic and SD rats, while total serum Trp concentrations were lower in analbuminemic rats than in SD rats. Although liver, brain, and muscle Trp concentrations after oral Trp administration under Trp depletion were lower in analbuminemic rats than in SD rats, the ratio of the liver Trp concentration in analbuminemic rats to that in SD rats was smaller than that of the brain or muscle Trp concentration. These results suggest that variations in serum albumin levels could affect the transport of orally administered Trp into the liver of rats with Trp depletion.  相似文献   
77.
Whereas in severe burns cultured human epithelial cells may well serve as a life saving method, the true value of tissue-engineered skin products in chronic wound care has yet to be clearly defined. Among other well-known clinical problems, the engraftment rate of commercially available multilayered "sheet grafts" has been shown to vary extremely. Adherence of transplanted cells to the wound bed--especially in the presence of potential wound contamination-- is one of the crucial aspects of this technique. Keratinocyte suspensions in a natural fibrin sealant matrix can potentially treat a variety of skin defects. In acute burn wounds, as well as in chronic wounds the clinical application of this type of tissue-engineered skin substitute demonstrates the capacity of cultured human autologous keratinocytes in a fibrin sealant matrix to adhere to wound beds, attach and spread over the wound resulting in reepithelialization of both acute and chronic wounds. In full thickness burns the combination of this new tool with allogenic dermis is a promising option to achieve complete dermal-epidermal reconstitution by means of tissue engineering and guided tissue repair. When transferring this technique into the treatment of chronic wounds we found an optimal preparation of such recipient wound beds to be crucial to the success. The additional application of continuous negative pressure (vacuum therapy) and preliminary chip skin grafting to optimally prepare the recipient site may be helpful tools to achieve such well-prepared and graftable surfaces. Prospective controlled comparative studies should be designed to further assess the clinical efficacy of this technique.  相似文献   
78.
Human serum amyloid P component (SAP) was expressed in the methylotrophic yeast Pichia pastoris. SAP cDNA was placed under control of regulatory sequences derived from the alcohol oxidase gene (AOX1), and its protein product was secreted using the Saccharomyces cerevisiae alpha-mating factor signal sequence. Recombinant SAP (r-SAP) was produced in a bioreactor with computer controlled fed-batch mode and purified by use of a C-terminal histidine tag. The yield of purified r-SAP was 3-4mg from 1L supernatant and 5-6mg from 1L cell paste, indicating that the majority of the produced SAP was not secreted. Treatment of the cell paste with EDTA increased the yield further by about 30%. The N-terminal of r-SAP purified from the supernatant showed non-complete cleavage of the alpha-mating factor signal sequence. Purified r-SAP, analyzed under native conditions, was shown to be a decamer, like purified human SAP (h-SAP), with monomers of 27kDa. Each monomer had one N-glycosylation site, positioned at the same site as for h-SAP. r-SAP bound to antibodies produced against h-SAP. Furthermore, r-SAP bound to ds DNA and influenza A virus subunits in a Ca(2+)-dependent manner and inhibited influenza A virus hemagglutination. These results indicate that r-SAP produced in P. pastoris has the same biological activity as purified h-SAP.  相似文献   
79.
Tartrate-resistant acid phosphatase (TRACP) is an enzyme with unknown biological function. In addition to its acid phosphatase activity, TRACP is capable of generating reactive oxygen species (ROS) at neutral pH. Two forms of TRACP circulate in human serum, macrophage-derived TRACP 5a and osteoclast-derived TRACP 5b. Here we have studied the circulating forms of the osteoclast-derived TRACP 5b in rat and human serum. In human serum, TRACP 5b circulates in a large complex that contained α2M and calcium. On the contrary, rat serum TRACP 5b circulates as a free molecule. Formation of the TRACP 5b complex in vitro decreased significantly the ROS generating activity of TRACP 5b without affecting its phosphatase activity. These results suggest that the complex formation may be necessary to eliminate the formation of the harmful ROS in the neutral pH of serum.  相似文献   
80.
Bone reconstruction can be performed with an autogeneic graft from various donor regions. Osteoconductive and osteoinductive bone substitutes originate from substances of diverse chemical and morphological types and can have a synthetic or a biological derivation. Alongside autogeneic bone transplants and allogenic and xenogeneic bone implants, alloplastic bone replacements of synthetic or semi-synthetic origin are being used for defect reconstruction. In an animal model in rabbits five bone substitutes and one autogeneic graft were surgically incorporated into identical bone defects (10times 10 mm in size) in six anatomically defined regions of the skull. With scintigraphic and histological methods, the metabolic dynamics of the bone is examined as it reacts to the transplantation of autogeneic bone or to implanted bone replacement material. The different autogeneic, xenogeneic and alloplastic bone replacement materials can be differentiated according to the functional quality of the new tissue and the dynamics of the bone conversion thus induced. In the comparison of mineralized, osteoconductive bone subsitutes (TCP, HA, calcium carbonate ceramics) with demineralized, osteoinductive implants (DBM new, DBM old) and autogeneic bone grafts, the bone inducing matrices show the largest quantity of new bone formation, making possible a volume-constant reconstruction. This revised version was published online in July 2006 with corrections to the Cover Date.  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