全文获取类型
收费全文 | 15971篇 |
免费 | 1306篇 |
国内免费 | 725篇 |
专业分类
耳鼻咽喉 | 143篇 |
儿科学 | 150篇 |
妇产科学 | 210篇 |
基础医学 | 2541篇 |
口腔科学 | 1359篇 |
临床医学 | 1042篇 |
内科学 | 2156篇 |
皮肤病学 | 439篇 |
神经病学 | 931篇 |
特种医学 | 303篇 |
外国民族医学 | 4篇 |
外科学 | 2003篇 |
综合类 | 2402篇 |
现状与发展 | 2篇 |
预防医学 | 515篇 |
眼科学 | 494篇 |
药学 | 1588篇 |
4篇 | |
中国医学 | 596篇 |
肿瘤学 | 1120篇 |
出版年
2024年 | 26篇 |
2023年 | 177篇 |
2022年 | 319篇 |
2021年 | 534篇 |
2020年 | 491篇 |
2019年 | 422篇 |
2018年 | 487篇 |
2017年 | 468篇 |
2016年 | 487篇 |
2015年 | 666篇 |
2014年 | 1000篇 |
2013年 | 1258篇 |
2012年 | 962篇 |
2011年 | 1171篇 |
2010年 | 969篇 |
2009年 | 972篇 |
2008年 | 1030篇 |
2007年 | 993篇 |
2006年 | 927篇 |
2005年 | 777篇 |
2004年 | 689篇 |
2003年 | 634篇 |
2002年 | 461篇 |
2001年 | 346篇 |
2000年 | 247篇 |
1999年 | 238篇 |
1998年 | 210篇 |
1997年 | 174篇 |
1996年 | 156篇 |
1995年 | 117篇 |
1994年 | 101篇 |
1993年 | 95篇 |
1992年 | 67篇 |
1991年 | 57篇 |
1990年 | 55篇 |
1989年 | 37篇 |
1988年 | 33篇 |
1987年 | 26篇 |
1986年 | 14篇 |
1985年 | 29篇 |
1984年 | 30篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1974年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
目的:探讨尿中转化生长因子-β1(TGF-β1)和细胞外基质(ECM)在各种慢性肾小球肾病患者中的变化及其临床意义。方法:将105例慢性肾小球患者进行临床和病理分组,采用酶联免疫吸附试验(ELISA)分别检测各组的尿TGF-β1水平,同时采用放射免疫分析法(RIA)检测尿中的各种ECM,所有检测值均用尿肌酐(Cr)浓度进行校正。结果:在不同临床分组中,尿TGF-β1/Cr和LN/Cr、PCⅢ/Cr、Ⅳ-C/Cr水平明显高于对照组(P〈0.05),尿HA/Cr水平则在Ⅲ、Ⅳ组中出现下降。而在不同的病理分组中,肾小球轻微病变(GML)组尿中TGF-β1、ECM与对照组比较无统计学意义,其他各病理分组则出现不同的变化。相关性分析尿TGF-β1/Cr与LN/Cr、PCⅢ/Cr、Ⅳ-C/Cr正相关,与HA/Cr无相关性。结论:通过尿TGF-β1和ECM在慢性肾小球肾病患者中的联合检测,对评价慢性肾小球肾病的进展和预后判断提供一定的临床价值。 相似文献
42.
改良消蚀法制备脱细胞真皮基质微粒及其生物相容性评价 总被引:1,自引:1,他引:0
目的:利用改良消蚀法制备一种新型脱细胞真皮基质(Acellular dermal matrix,ADM)微粒,并对其相容性加以评价,为组织工程微粒皮肤的制备奠定研究基础。方法:应用机械法切除猪真皮乳头层,结合消蚀法和冻融法除去网状真皮中的所有细胞制备成ADM,将ADM搅碎成颗粒状,对其做细胞毒性实验和皮下埋藏实验检验其相容性。结果:该方法制备的ADM微粒韧性好,细胞去除完全,胶原三维稍松散但结构完整,无基底膜和乳头层。细胞毒性实验显示其基本无毒性,成纤维细胞在ADM微粒上增殖良好,皮下埋藏试验未见明显排异反应,ADM微粒能诱导血管和成纤维细胞长入。结论:用改良消蚀法制备的ADM微粒抗原性低、相容性好,可以作为组织工程微粒皮肤的支架和填充材料。 相似文献
43.
不同种属脱细胞真皮与自体皮复合移植的比较性研究 总被引:5,自引:2,他引:3
目的 观察不同种属脱细胞真皮基质 (acellulardermalmatrix,ADM)与自体皮复合移植的效果 ,为异种ADM的临床应用提供理论依据。 方法 本地产白色小猪 6头 ,分为异种 (人 )ADM +自体刃厚皮组 (A组 )、同种异体 (猪 )ADM +自体刃厚皮组 (B组 )、单纯自体刃厚皮组 (C组 )及单纯自体中厚皮组 (D组 )。观察术后 2、4、8、12、2 4周内移植物存活率 ,以及移植皮片收缩程度、移植区组织学变化等情况。 结果 A、B组移植后皮片外观光滑、有弹性 ;两组均获得了满意的皮片成活率 ,并可迅速诱导成纤维细胞、血管内皮细胞等宿主修复细胞的长入 ;两组移植皮片收缩面积有大于C、D组的趋势 (P <0.0 5);术后 2 4周移植区组织与单纯中厚皮移植组织结构一致。 结论 在观察期内(复合移植后 2 4周 ) ,与自体皮复合移植时 ,同、异种ADM具有相近的生物学作用 ,异种来源的ADM可能具有更广阔的应用前景 相似文献
44.
Development of the neural crest involves a remarkable feat of coordinated cell migration in which cells detach from the neural tube, take varying routes of migration through the embryonic tissues and then differentiate at the end of their journey to participate in the formation of a number of organ systems. In general, neural crest cells appear to migrate without the guidance of long-range physical or chemical cues, but rather they respond to heterogeneity in the extracellular matrix that forms their migration substrate. Molecules such as fibronectin and laminin act as permissive substrate components, encouraging neural crest cell attachment and spreading, whereas chondroitin sulphate proteoglycans are nonpermissive for migration. A balance between permissive and nonpermissive substrate components seems to be necessary to ensure successful migration, as indicated by a number of studies in mouse mutant systems where nonpermissive molecules are over-expressed, leading to inhibition of neural crest migration. The neural crest expresses cell surface receptors that permit interaction with the extracellular matrix and may also modify the matrix by secretion of proteases. Thus the principles that govern the complex migration of neural crest cells are beginning to emerge. 相似文献
45.
L.H. JASPARS E. BLOEMENA P. BONNET P. VAN DER VALK C.J.L.M. MEIJER 《Histopathology》1995,26(2):113-121
In this study the distribution patterns of various extracellular matrix components and their receptors (i.e. β1 integrins) in B-cell non-Hodgkin lymphomas were examined and compared to those in reactive lymphoid tissue. Neoplastic follicles within follicular lymphomas showed similar patterns to that observed in reactive follicles, which appeared to be strongly associated with the presence of follicular dendritic cells. Diffuse lymphomas of low and intermediate malignancy grade revealed features comparable to those of interfollicular areas of reactive lymphoid tissue, irrespective to which compartment the tumour cells were related. Highly malignant lymphomas, however, displayed unique extracellular matrix configurations, resulting from active matrix degradation by macrophages; this may support rapid tumour growth. Extranodal lymphomas showed virtually the same matrix patterns as their nodal counterparts, suggesting that (malignant) lymphoid cells generate (at least partly) their own specific microenvironment. In reactive lymphoid tissue β1 integrins were mainly found on resident cells and except for α4, α5 (and β1) the lymphoid cells expressed very little, if any, β1 integrins. In comparison, expression of these integrins on lymphoma cells was reduced (follicular lymphomas) or could not be detected at all (diffusely growing lymphomas); this might contribute to the growth pattern and metastatic properties of the tumours. 相似文献
46.
47.
为探讨前列腺癌(PCa)细胞的转移机制,应用免疫组织化学ABC法在良性前列腺增生(BPH)及PCa组织中对基膜连接蛋白(LN),胶原Ⅳ型蛋白(COLⅣ),纤维连接蛋白(FN)等细胞外基质(ECM)蛋白的表达进行检测,结果BPH组织中基底膜部位LN,COLⅣ及FN的染色呈连续线状分布,PCa组组织基底膜部位LN,COLⅣ及FN的阳性染色呈碎片状或断线状分布。COLⅣ在BPH与PCa组织中的强阳性率无显著性差异(P>0.05)。结果提示ECM在PCa组织中基底膜部位的明显缺失(非连续线状分布)可能是肿瘤转移的重要因素。 相似文献
48.
尿核基蛋白22检测在膀胱癌诊断中的价值 总被引:1,自引:0,他引:1
目的:探讨尿核基蛋白22(NMP22)在膀胱移行细胞癌诊断中的临床价值。方法:采用ELISA法定量分析16例膀胱移行上皮癌(TCC)、14例TCC术后随访患者和12例泌尿系良性疾病患者的尿NMP22含量,并同时行尿脱落细胞学检查。设定NMP22的临界值为10U/ml。结果:16例膀胱移行癌患者、14例膀胱癌术后随访患者和12例泌尿系良性疾病患者的尿NMP22中位值分别为31.65、5.41和6.74U/ml,前者与后两者均有统计学差异(P<0.001)。以10U/ml为界值,尿NMP22诊断膀胱癌的敏感性为93.7%,特异性为69.2%,阴性预测值为94.7%,准确性为78.6%。同期尿细胞学的敏感性为31.3%,特异性100%,阴性预测值为70.2%。结论:与脱落细胞学比较,尿NMP22测定有更高的敏感性,是一种较理想的早期膀胱移行细胞癌诊断指标,对预后判断亦有价值。 相似文献
49.
Amanda M. Cockshutt Laurent Jonet Jean-Claude Jeanny Marc Vigny Dr. Daniel Raulais 《Developmental dynamics》1994,200(3):198-211
Retinoic acid induced heparin-binding protein (RIHB) is a highly basic, soluble polypeptide of the chick embryonic extracellular matrix. We have examined the expression and localization of RIHB during very early embryogenesis by in situ hybridization and immunohistochemistry. RIHB mRNA is very weakly detectable above background in the blastodiscs of unincubated eggs. The expression increases greatly over the first 24 hours of incubation, and is observed throughout the blastodisc in all three of the germ layers following gastrulation. As neurulation occurs, the expression becomes more restricted to certain areas, notably the ectoderm, the neural folds, and especially the notochord. After the neural tube has formed the expression in the tube itself decreases dramatically, whereas the expression in the head ectoderm and the notochord persists. After 72 hours of incubation expression remains relatively high throughout most of the embryo, with higher levels of expression in regions undergoing organogenesis and lower levels in organs which have already differentiated. RIHB protein is also weakly detectable in unincubated eggs as patches of immunoreactive material between the blastodisc and the vitelline. After 6 hours of incubation small regions of basement membrane are immunoreactive. RIHB is detected in this matrix, apparently before even fibronectin. The amount of RIHB protein increases dramatically over the first 24 hours of incubation. It is found in basement membrane separating the epiblast from the hypoblast, then later in that separating the ectoderm from the mesoderm. It is also detected surrounding individual cells, especially of the ectodermal layer. During neurulation RIHB is observed in the basement membrane surrounding the neural fold and the notochord, and in the lamina separating the ectodermal, mesodermal, and endodermal layers. Later in development, RIHB is detected in the basement membrane under the epidermis, throughout the developing limbs, and in the lamina of various developing organs, such as the eye, the pulmonary bud, the intestine, and the mesonephros. These results demonstrate that RIHB is highly expressed during the early embryonic period, by all three germ layers, and is an important and very early component of the embryonic extracellular matrix. Its very broad expression and localization argue for a more general role in development than its demonstrated weak neurotrophic activity. © 1994 Wiley-Liss, Inc. 相似文献
50.