全文获取类型
收费全文 | 67289篇 |
免费 | 7886篇 |
国内免费 | 2530篇 |
专业分类
耳鼻咽喉 | 126篇 |
儿科学 | 1901篇 |
妇产科学 | 290篇 |
基础医学 | 6306篇 |
口腔科学 | 362篇 |
临床医学 | 5832篇 |
内科学 | 13381篇 |
皮肤病学 | 239篇 |
神经病学 | 298篇 |
特种医学 | 2782篇 |
外国民族医学 | 96篇 |
外科学 | 5514篇 |
综合类 | 12781篇 |
现状与发展 | 13篇 |
预防医学 | 2679篇 |
眼科学 | 176篇 |
药学 | 6250篇 |
41篇 | |
中国医学 | 3948篇 |
肿瘤学 | 14690篇 |
出版年
2024年 | 234篇 |
2023年 | 1269篇 |
2022年 | 2315篇 |
2021年 | 3400篇 |
2020年 | 3141篇 |
2019年 | 2657篇 |
2018年 | 2569篇 |
2017年 | 3007篇 |
2016年 | 3116篇 |
2015年 | 3274篇 |
2014年 | 4611篇 |
2013年 | 4744篇 |
2012年 | 4262篇 |
2011年 | 4533篇 |
2010年 | 3641篇 |
2009年 | 3381篇 |
2008年 | 3382篇 |
2007年 | 3601篇 |
2006年 | 3168篇 |
2005年 | 2787篇 |
2004年 | 2197篇 |
2003年 | 1762篇 |
2002年 | 1472篇 |
2001年 | 1323篇 |
2000年 | 1034篇 |
1999年 | 824篇 |
1998年 | 741篇 |
1997年 | 700篇 |
1996年 | 609篇 |
1995年 | 464篇 |
1994年 | 476篇 |
1993年 | 352篇 |
1992年 | 369篇 |
1991年 | 300篇 |
1990年 | 282篇 |
1989年 | 213篇 |
1988年 | 222篇 |
1987年 | 196篇 |
1986年 | 177篇 |
1985年 | 157篇 |
1984年 | 130篇 |
1983年 | 85篇 |
1982年 | 116篇 |
1981年 | 87篇 |
1980年 | 87篇 |
1979年 | 61篇 |
1978年 | 44篇 |
1977年 | 40篇 |
1976年 | 26篇 |
1975年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
131.
Objective Sstudy effect of nuclear factor-κB ASOND on I type collagen expression and rat hepatic stellate cells(HSC)proliferation.Methods Rat HSCs were separated by affusing and digestingof Ⅳ type collagenenzyme and density acentric method.Lipid-mediated NF-κB p65 ASOND(0.001,0.01,0.1,1μmol/L)Was transferred into rat HSCs.Toxicity of HSCs caused by NF-κB p65 ASOND and activity of LDH were determined by trypan blue staining.Proliferation affection of transferring NF-κB p65 ASOND into HSCs was determined by MTT.In different concentration NF-κB p65 ASOND.expression of Ⅰ type collagen stimulated by 1mg/L TNF-αwas determined by RT-PCR and ELISA.Results After transfection of NF-κB p65 ASODN,expression of NF-κB protein in HSCs was decreasing.Toxicity experiment indicated that NF-κB p65 ASOND of different concentration(0.001,0.01,0.1 and 1.0 μmol/L)had no effect on HSCs livability and LDH activity(P<0.05).Four different concentration NF-κ B p65 ASOND could restrain HSCs proliferation stimulated by 1 mg/L TNF-α.The expression of I type collagen and mRNA stimulated by 1mg/LTNF-αwas increased,and had a positive correlation with concentration(P>0.05).Conclusion NF-κB p65 ASOND may depress NF-κB activity to restrain HSCs proliferation and Ⅰ type collagen expression,and reduce extracellular matrix. 相似文献
132.
Wing‐Hong Li Moon‐Tong Cheung Candace N.S. Ho Ting‐Pong Fung Kai‐Ming Ko Kelvin K.W. Yau 《Surgical Practice》2007,11(4):138-143
Aim: To examine the survival benefit of liver and lung resection for colorectal metastasis and the potential prognostic factors that affect patient survival. Methods: All patients who had resection of lung or liver metastasis for colorectal metastasis in Queen Elizabeth Hospital, Hong Kong from 1995 to 2004 were retrospectively reviewed. The overall and disease‐free survival was analysed, in particularly between liver and lung metastasis. All factors that may have affected the survival were entered into Cox's proportional hazards regression model to identify significant variables associated with survival. Results: At 5 years, the overall survival of patients who had resection of lung and liver metastasis was 44% and 38%, respectively; the disease‐free survival was 26% and 24%, respectively. Overall and disease‐free survival of patients with resection of lung metastasis was comparable to those with resection of liver metastasis. The differentiations of primary tumour and time to metastasis were shown to be significant prognostic factors influencing overall survival. Those patients with systemic chemotherapy after resection of colorectal metastasis demonstrated a significantly higher probability of overall survival. Conclusion: Resection of lung and liver metastases from colorectal origin was safe and both procedures improved survival. The use of chemotherapy after resection of metastasis significantly improved the overall survival. 相似文献
133.
Vascular Endothelial Growth Factor Expression and Cyclosporine Toxicity in Renal Allograft Rejection 总被引:3,自引:0,他引:3
B. Handan Özdemir F. Nurhan Özdemir Nihan Haberal Remzi Emiroglu Beyhan Demirhan Mehmet Haberal 《American journal of transplantation》2005,5(4):766-774
The aim of this study was to evaluate the influence of vascular endothelial growth factor (VEGF) on renal function and on development of interstitial fibrosis (IF) in renal allografts. Tubular and interstitial expressions of VEGF and TNF-α, and density of macrophages in the interstitium were examined in 92 patients with nonrejected kidneys, acute rejection (AR), chronic allograft nephropathy (CAN), borderline changes (BC) and acute cyclosporin A (CsA) toxicity. Follow-up biopsy specimens from patients with AR and BC were evaluated for development of IF. A significant difference in tubular and interstitial VEGF expressions was found between patients with AR, BC, CAN and CsA toxicity (p < 0.001). Macrophage infiltration was positively correlated with VEGF and TNF-α expressions (p < 0.001). VEGF expression increased with increasing expression of TNF-α (p < 0.001). Renal function in first 6 months after initial biopsy was better in patients with marked tubular VEGF expression (p < 0.01); however, in follow-up, development of IF and graft loss was found earlier in these patients (p < 0.01 and p < 0.05, respectively). Increased renal VEGF expression has protective properties immediately following renal allograft but allows for increased risk of early IF, and therefore poor graft outcome in the long term. 相似文献
134.
蛋白酶激活受体1介导人肺上皮细胞分泌白细胞介素-8 总被引:1,自引:0,他引:1
目的探讨蛋白酶激活受体1(PAR1)激动肽和凝血酶对人肺上皮细胞白细胞介索-8(IL-8)分泌的影响。方法人肺上皮细胞系A549细胞分别接种于12孔培养板各孔内,并分别用不同浓度的PAR1激动肽SFLLR和反PAR1激动肽RLLFS以及不同浓度的凝血酶和/或凝血酶抑制剂水蛭索进行刺激,刺激时间为2和16h。用ELISA方法检测上清液中的IL-8水平。结果经过16h的培养,SFLLR可引起浓度相关性IL-8的释放增加,增加到300μmol/L时诱导IL-8的释放量比基础分泌量增加了近16倍,RLLFS不能引起IL-8的释放增加。凝血酶也可引起浓度相关性IL-8释放.凝血酶在浓度1kU/L时就可引起IL-8释放量增加,10kU/L时诱导IL-8释放量达高峰,为基础分泌量的7.5倍。水蛭索可以抑制凝血酶对IL-8的释放作用。时间相关曲线表明,PAR1介导的IL-8释放从2h起即可引起增加,16h达高峰。结论PAR1激动肽和凝血酶可促进人肺上皮细胞分泌IL-8,PAR1拮抗剂和凝血酶抑制剂可能具有抗炎作用。 相似文献
135.
Hiroko Utsunomiya Wanninayake M. Tilakaratne Kazufumi Oshiro Satoshi Maruyama Makoto Suzuki Hiroko Ida-Yonemochi Jun Cheng Takashi Saku 《Journal of oral pathology & medicine》2005,34(8):498-507
BACKGROUND: Oral submucous fibrosis (OSF) is a chewing habit-related pre-cancerous condition of the oral mucosa affecting predominantly south Asians. It is histopathologically characterized by epithelial atrophy and fibrosis of the subepithelial connective tissue. Fibrosis extends all the way into the muscle layer, leading to difficulty in mouth opening. However, the dynamics of extracellular matrix (ECM) remodeling with OSF progression is largely unknown. METHODS: Forty biopsy specimens of OSF and 10 of normal buccal mucosa were examined for expression/deposition modes of eight ECM molecules by histochemistry, immunohistochemistry, and in situ hybridization. RESULTS: In the early stage of OSF, tenascin, perlecan, fibronectin, collagen type III were characteristically enhanced in the lamina propria and the submucosal layer. In the intermediate stage, the ECM molecules mentioned above and elastin were extensively and irregularly deposited around muscle fibers. In the advanced stage, such ECM depositions decreased and were entirely replaced with collagen type I only. Their gene expression levels varied with progression of fibrosis, but the mRNA signals were confirmed in fibroblasts in the submucosal fibrotic areas. CONCLUSIONS: The results indicate that the ECM remodeling steps in OSF are similar to each phase of usual granulation tissue formation. Restricted mouth opening may be a result of loss of variety of ECM molecules including elastin into the homogeneity of collagen type I replacing muscle fibers. 相似文献
136.
137.
138.
Densities in dependent lung regions during anaesthesia: atelectasis or fluid accumulation? 总被引:2,自引:0,他引:2
Å. Strandberg G. Hedenstierna L. Tokics H. Lundquist B. Brismar 《Acta anaesthesiologica Scandinavica》1986,30(3):256-259
In previous studied with computed tomography (CT) prior to and during general anaesthesia, we found that densities developed in dependent parts of the lungs immediately after induction of anaesthesia in all examined patients. It was suggested that the densities were atelectases created by compression of lung tissue but an alternative explanation could be accumulation of extravascular fluid in the lung tissue and/or in the pleural space. In the present study the nature of the densities was analysed in further detail. Injections of contrast medium into the pleural space revealed that the densities were located in the lung tissue and not in the pleural space. By injecting contrast medium intravenously and repeating the CT scanning over a 2-min period the passage of contrast through the major vessels and the lung densities could be studied. The transit time of the contrast medium was of the same magnitude in the densities and the major lung vessels. This indicates that there were no regions with an increased amount of extravascular fluid to delay the contrast passage. These findings oppose the idea of fluid accumulation as the cause of the densities, while atelectasis remains the most plausible explanation. 相似文献
139.
Metabolism is one of the major determinants for age-related changes in susceptibility to chemicals. Aldehydes are highly reactive molecules present in the environment that also can be produced during biotransformation of xenobiotics and endogenous metabolism. Although the lung is a major target for aldehyde toxicity, early development of aldehyde dehydrogenases (ALDHs) in lung has been poorly studied. The expression of ALDH in liver and lung across ages (postnatal day 1, 8, 22, and 60) was investigated in Wistar-Han rats. In adult, the majority of hepatic ALDH activity was found in mitochondria, while cytosolic ALDH activity was the highest contributor in lung. Total aldehyde oxidation capability in liver increases with age, but stays constant in lung. These overall developmental profiles of ALDH expression in a tissue appear to be determined by the different composition of ALDH isoforms within the tissue and their independent temporal and tissue-specific development. ALDH2 showed the most notable tissue-specific development. Hepatic ALDH2 was increased with age, while the pulmonary form did not. ALDH1 was at its maximum value at postnatal day 1 (PND1) and decreased thereafter both in liver and lung. ALDH3 increased with age in liver and lung, although ALDH3A1 was only detectible in lung. Collectively, the present study indicates that, in the case of aldehyde exposure, the in vivo responses would be tissue and age dependent. 相似文献
140.
The intercostal hernia of the lung is a very rare extraordinary disease that requires operation because of the complaints
and potential complications. The authors review cases of their operations and analyze the subsequence and treatment. Three
patients have been treated for intercostal lung hernia in our treatment. The causes of this disease were a previous thoracotomy
in one case and fits of coughing in the other two cases. The diagnosis was set up on the grounds of the specific clinical
symptoms, thoracic X-ray and CT scan. The hernia was dissolved with percostal stitches and with the suture of the thoracic
musculature in two cases. Plastic operation of the thoracic wall by implanting a polypropylene surgical mesh (Prolen, Ethicon,
Johnson & Johnson) was performed in the case of the third patient and later in the first two patients due to recrudescence.
In one case the authors were constrained to resect the dystelectasial lung in the hernial sac. The three patients had been
operated five times. Relapse of hernia was detected in two patients, in whom the intercostal space had been reconstructed
with percostal stitches. We did not detect any relapsing in those two patients at 33 and 66 months after the second operation
with mesh implantation. The third patient who got mesh implant immediately did not relapse 12 months after the operation.
Intercostal lung hernia is an indication of operation. A plastic operation of the thoracic wall combined with the implantation
of a surgical mesh is recommended to close the hernial orifice, which is suitable for treating both primary and relapsed hernias.
Recurrence is rare in those patients treated with this method. 相似文献