全文获取类型
收费全文 | 1281篇 |
免费 | 93篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 13篇 |
妇产科学 | 83篇 |
基础医学 | 263篇 |
口腔科学 | 98篇 |
临床医学 | 79篇 |
内科学 | 136篇 |
皮肤病学 | 39篇 |
神经病学 | 86篇 |
特种医学 | 14篇 |
外科学 | 93篇 |
综合类 | 248篇 |
预防医学 | 32篇 |
眼科学 | 47篇 |
药学 | 72篇 |
中国医学 | 36篇 |
肿瘤学 | 79篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 18篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 28篇 |
2017年 | 26篇 |
2016年 | 26篇 |
2015年 | 41篇 |
2014年 | 54篇 |
2013年 | 90篇 |
2012年 | 38篇 |
2011年 | 60篇 |
2010年 | 53篇 |
2009年 | 44篇 |
2008年 | 48篇 |
2007年 | 52篇 |
2006年 | 53篇 |
2005年 | 41篇 |
2004年 | 48篇 |
2003年 | 43篇 |
2002年 | 48篇 |
2001年 | 44篇 |
2000年 | 46篇 |
1999年 | 36篇 |
1998年 | 48篇 |
1997年 | 48篇 |
1996年 | 37篇 |
1995年 | 50篇 |
1994年 | 37篇 |
1993年 | 28篇 |
1992年 | 22篇 |
1991年 | 26篇 |
1990年 | 22篇 |
1989年 | 21篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 7篇 |
1985年 | 20篇 |
1984年 | 22篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
排序方式: 共有1429条查询结果,搜索用时 15 毫秒
1.
MASAO TSUJIHATA KAZUHIRO YOSHIMURA KOZO TSUJIKAWA NORIHIDE TEI AKIHIKO OKUYAMA 《International journal of urology》2006,13(6):743-746
BACKGROUND: Fibronectin (FN; 230 kDa) is a multifunctional alpha2-glycoprotein distributed throughout the extracellular matrix and body fluids. We recently reported that FN has a protective effect against injury of renal tubular cells by exposure to oxalate and calcium oxalate (CaOX) crystals and inhibits the adhesion of CaOX crystals to renal tubular cells. In the study presented here, we investigated whether FN has inhibitory effect on crystal endocytosis by renal tubular cells. METHODS: The inhibitory effect of FN on endocytosis of CaOX crystals by MDCK cells was examined by using a radioactivity uptake assay. Also, crystal endocytosis by cells was morphologically assessed by means of transmission electron microscopy (TEM). RESULTS: FN had inhibitory effects on CaOX crystal endocytosis by MDCK cells. The morphological TEM study showed that few crystals were taken into cells when FN was added compared to the number of crystals when FN was not added. CONCLUSION: We found that FN had the inhibitory effects on the interaction between crystals and renal tubular cells, including the adhesion or endocytosis of crystals by cells. 相似文献
2.
采用火箭电泳法对64例(80例次)肺性病患者进行血浆纤维连接蛋白(Fn)测定。合并肺性脑病19例,并与106例健康人及104例其他呼吸疾患进行对比.结果表明:正常组、肺性病缓解组、急性发作组、肺性脑病组血浆Fn水平分别为34.27±6.36mg/dl,29.61±4.25ms/dl,15.21±5.20mg/dl,11.82±5.67mg/dl.肺性脑病患者血浆Fn显著降低,并随病情恶化而进一步下降。同时,其含量变化与pH值和PaO2呈正相关,与PaCO2,呈负相关。因此动态观察肺性脑病患者血浆Fn含量可作为判断顶后一项较为可靠的指标。 相似文献
3.
P Damas A Adam J Buret C Renard M Lamy J B Foidart P Mahieu 《European journal of clinical investigation》1987,17(2):166-173
An enzyme-linked immunoassay has been recently set up for direct measurement of the binding capacity of plasma fibronectin to gelatin. This binding capacity could be completely inhibited in vitro by an eight-fold excess of gelatin, of Haemaccel, but not of Geloplasma. On the contrary, the levels of immunoreactive fibronectin measured by laser nephelometry did not change, in presence of 10 to 1000 micrograms ml-1 of gelatin, of Haemaccel or of Geloplasma. When infused into normal volunteers, Haemaccel provoked a strong and immediate inhibition of the plasma fibronectin binding capacity to gelatin. This inhibition was dose-dependent and maximal after infusion of 500 ml of Haemaccel. Twenty-four hours after this infusion, there was a progressive recovery of the gelatin-binding capacity, which was almost completely achieved 96 h later. The formation of complexes between Haemaccel and fibronectin was demonstrated by gel filtration chromatography and by affinity chromatography. Immunoreactive plasma fibronectin levels remained unchanged up to 24 h after infusion of 500 ml of Haemaccel. A transient decline to 50% of its initial value then occurred the second day after the infusion. Therefore, a delay existed between the formation of fibronectin-Haemaccel complexes and their elimination from the bloodstream. This delay decreased when smaller volumes of Haemaccel were infused, which strongly suggests that plasma fibronectin is cleared by means of Haemaccel and does not seem to play a role of opsonin in these conditions.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
4.
5.
E. N. KOSMAS C. N. BAXEVANIS M. PAPAMICHAIL & T. KORDOSSIS 《European journal of clinical investigation》1997,27(4):308-315
Our objective was to investigate the initial levels of circulating proinflammatory cytokines, such as interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumour necrosis factor alpha (TNF-α), of certain acute-phase proteins, such as C-reactive protein (CRP), fibrinogen (FBN) and albumin, and of the glycoprotein fibronectin at presentation and their daily variation during the clinical course of community-acquired pneumonia (CAP) in relation to clinical and laboratory indices of infection. Thirty otherwise healthy hospitalized patients aged 48 ± 3 years (mean ± SEM) and with bacteriologically confirmed CAP were studied prospectively. IL-1β and IL-6 were found to be 15-fold higher on admission (122 ± 9 pg mL?1 and 60 ± 4 pg mL?1 respectively), whereas TNF-α was three-fold higher (102 ± 5 pg mL?1) than those of controls, all of them showing a decline towards normal. Initial CRP levels were increased 90-fold (416 ± 1 mg L?1), whereas fibronectin levels were reduced (242 ± 9 mg dL?1). The presence of parapneumonic effusion was associated with a higher TNF-α serum level (127 ± 7 vs. 86 ± 4 pg mL?1, P = 0.0002), a more rapid daily decline in TNF-α (–7.2 ± 0.7 vs. ?3.8 ± 0.5 pg mL?1 day?1, P = 0.0005), a slower rate of decline in CRP (?42.8 ± 3.0 vs. ?54.6 ± 3.0 mg L?1 day?1, P = 0.02) and a slower rate of increase in FBN (5.9 ± 1.0 vs. 11.7 ± 1.0 mg dL?1 day?1), P = 0.001]. Furthermore, daily progression of serum levels of cytokines and acute-phase proteins correlated strongly with pyrexia, erythrocyte sedimentation rate (ESR), neutrophil count, alveolar–arterial oxygen difference and radiographic resolution, clinically manifested by improvement in the patients' condition. 相似文献
6.
Michael Schirner Frank Herzberg Roland Schmidt Michael Streit Michael Schoning Michael Hummel Christine Kaufmann Eckhard Thiel Ernst-Dieter Kreuser 《Clinical & experimental metastasis》1997,16(5):427-435
The integrin 51 seems to be the most relevant receptor of tumor cells for binding to fibronectin. Although numerous studies suggest a role of tumor cell fibronectin interaction in tumor metastasis, differential integrin expression on tumor cells has, however, not been correlated with metastatic capabilities. We addressed this question by transfection of the integrin 51 cDNA into HT-29 human colon carcinoma cells which led to de novo expression of functional integrin 51. Similar to other reports, expression of the integrin 51 in HT-29 tumor cells exerted an inhibitory action on cell proliferation as indicated in our study by formation of fewer colonies in soft agar. The tumor growth inhibitory property of the integrin 51 was also shown by reduction of subcutaneous xenograft growth in nude mice to approximately 50% of that of control transfectants. For the first time, we found that several clones of integrin 5 subunit transfectants displayed dramatically reduced formation of lung colonies and cutaneous metastasis after intravenous injec-tion into nude mice. While most animals inoculated with control transfectant cells formed macroscopically visible lung colonies ranging from 12.6 ± 2.6 to 22.0 ± 6.6 (mean colony number ± SEM), mice inoculated with HT-29 cell clones expressing the integrin a5b1 were almost completely free of lung colonies (ranging from 0.0 ± 0 to 0.2 ± 0.1). Our results imply that integrin 51 expression inhibits circulating tumor cells in pursuing late steps of the metastatic process as represented by the artificial metastasis (lung colonisation) model. © Rapid Science Ltd. 相似文献
7.
采用免疫组化及免疫电镜技术对临床胃粘膜活检及胃癌手术标本进行了纤维连结蛋白(FN)的定位观察。结果,FN见于胃粘膜上皮细胞和部分癌细胞内以及各种基底膜、间质中。肠化及异型增生上皮细胞FN染色增强,胃癌细胞和其基膜FN减少缺失且与癌细胞分化程度相关,胃癌间质FN丰富,尤其以癌浸润前缘明显。本文着重讨论了胃癌FN改变与癌细胞生物学特性的关系。 相似文献
8.
The OPAR mouse monoclonal antibody (mAb) directed against rat hepatocytes was previously shown to inhibit adhesion of TA3/Ha mammary carcinoma cells to hepatocytes. The antigen is abundantly present at the surface of hepatocytes beneath the endothelium of liver capillaries where we have observed invasion of carcinoma cells to occur. The OPAR mAb reacted with three major bands on a Western blot of liver plasma membrane proteins. The same proteins were also seen upon immunoprecipitation from iodinated liver plasma membrane proteins. We have isolated OPAR antigens by lectin wheat germ agglutinin (WGA) and OPAR affinity chromatography. Amino acid sequence analysis revealed that two of the bands were 1-macroglobulin and C4-binding protein, which are serum components produced by hepatocytes. The presence of the epitope on distinct proteins and our previous observation that it can be detected in the Golgi apparatus but not in the endoplasmic reticulum, suggested that OPAR reacts with a liver-specific glycoconjugate. Loss of OPAR reactivity after neuraminidase and N-glycosidase F treatment showed that the epitope contains sialic acid residues on N-linked sugar moieties. OPAR also reacted with rat fibronectin, and inhibited adhesion of TA3/St cells to fibronectin. This explains the inhibition by the OPAR mAb of TA3/St cell adhesion to hepatocytes, which we have shown to be due mainly to interaction with hepatocyte surface-associated fibronectin. However, adhesion of the related TA3/Ha cells to hepatocytes, which is mediated by the 6P4 integrin, and does not involve binding to fibronectin, is also inhibited. This suggests that 64 on liver-metastasizing carcinoma cells binds to an OPAR epitope-carrying glycoprotein produced by hepatocytes. 相似文献
9.
利用光镜、电镜、免疫组化和形态学定量技术动态研究维生素A对大鼠四氯化碳肝纤维化的抑制作用。结果表明,维生素A可减少四氯化碳中毒大鼠肝内纤维连接蛋白和Ⅰ、Ⅲ型胶原沉积,抑制贮脂细胞向成纤维细胞转化,并可明显地减轻肝纤维化程度。本文还对维生素A抑制肝纤维化的机理及意义作了初步探讨。 相似文献
10.
Garcia-Gila M Lopez-Martin EM Garcia-Pardo A 《Clinical and experimental immunology》2002,127(3):455-462
Apoptosis is a regulated event crucial to the development and proliferation of normal and malignant B cells. We have studied the role of signals delivered via alpha4 integrin on apoptosis triggered by three different pathways on these cells. For apoptosis induced by serum deprivation, culturing B cells on the recombinant fibronectin fragment H89, a known ligand for alpha4beta1 integrin, resulted in statistically significant (P < 0.005) higher viability values (68%, 65% and 67%) for Ramos, Nalm-6 and EHEB cells, respectively, than culturing cells on poly lysine (42%, 42% and 48%). An antialpha4 MoAb reverted the protecting effect, thus confirming that it was due specifically to alpha4 engagement. Similarly, cells cultured on FN-III4-5, a recently identified fibronectin region which binds activated alpha4 integrin, also showed statistically significant higher viability than poly lysine cultures. Alpha4 engagement however, did not prevent apoptosis induced on Ramos cells via surface IgM. Adhesion of IM-9 cells, a myeloma cell line carrying functional Fas receptors, to the H89 fragment neither increased cell viability upon triggering apoptosis via Fas when compared to poly lysine. These results indicate that alpha4 signalling may overcome B cell apoptosis induced by the lack of growth factors but does not seem to affect the IgM or Fas apoptotic pathways, thus suggesting different intracellular mechanisms for these processes. 相似文献