全文获取类型
收费全文 | 12562篇 |
免费 | 1313篇 |
国内免费 | 484篇 |
专业分类
耳鼻咽喉 | 178篇 |
儿科学 | 190篇 |
妇产科学 | 409篇 |
基础医学 | 1995篇 |
口腔科学 | 225篇 |
临床医学 | 1050篇 |
内科学 | 1740篇 |
皮肤病学 | 205篇 |
神经病学 | 606篇 |
特种医学 | 291篇 |
外国民族医学 | 5篇 |
外科学 | 876篇 |
综合类 | 2016篇 |
现状与发展 | 4篇 |
预防医学 | 745篇 |
眼科学 | 256篇 |
药学 | 1249篇 |
6篇 | |
中国医学 | 413篇 |
肿瘤学 | 1900篇 |
出版年
2024年 | 13篇 |
2023年 | 130篇 |
2022年 | 226篇 |
2021年 | 381篇 |
2020年 | 326篇 |
2019年 | 458篇 |
2018年 | 427篇 |
2017年 | 464篇 |
2016年 | 543篇 |
2015年 | 600篇 |
2014年 | 878篇 |
2013年 | 960篇 |
2012年 | 740篇 |
2011年 | 838篇 |
2010年 | 640篇 |
2009年 | 583篇 |
2008年 | 591篇 |
2007年 | 578篇 |
2006年 | 541篇 |
2005年 | 492篇 |
2004年 | 474篇 |
2003年 | 459篇 |
2002年 | 358篇 |
2001年 | 342篇 |
2000年 | 339篇 |
1999年 | 243篇 |
1998年 | 218篇 |
1997年 | 210篇 |
1996年 | 140篇 |
1995年 | 122篇 |
1994年 | 136篇 |
1993年 | 96篇 |
1992年 | 83篇 |
1991年 | 54篇 |
1990年 | 60篇 |
1989年 | 57篇 |
1988年 | 49篇 |
1987年 | 47篇 |
1986年 | 51篇 |
1985年 | 61篇 |
1984年 | 53篇 |
1983年 | 44篇 |
1982年 | 65篇 |
1981年 | 40篇 |
1980年 | 21篇 |
1979年 | 30篇 |
1978年 | 23篇 |
1977年 | 20篇 |
1976年 | 21篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
肾细胞癌中抑癌基因PTEN的表达及生物学意义 总被引:2,自引:3,他引:2
目的 :研究抑癌基因PTEN在肾细胞癌的表达及其生物学意义。方法 :应用免疫组织化学S P法检测 5例正常肾组织、18例癌旁肾组织和 40例肾细胞癌组织中抑癌基因PTEN的表达。结果 :5例正常肾组织和 18例癌旁肾组织均有较强的PTEN蛋白的表达 ,二者PTEN蛋白的表达强度、阳性细胞的分布形式无差异。抑癌基因PTEN在肾细胞癌中的表达不同于正常肾组织和癌旁肾组织 ,12 5 %的肾细胞癌呈PTEN蛋白阴性 ;17 5 %的肾细胞癌PTEN蛋白呈弱阳性 ;70 %的肾细胞癌PTEN蛋白呈阳性或强阳性 ,与癌旁组织PTEN蛋白的染色强度无差异。PTEN蛋白阴性的肾细胞癌 ,肾门淋巴结转移率为80 % ;PTEN蛋白阳性的肾细胞癌 ,肾门淋巴结转移率为 2 0 %。PTEN蛋白阴性肾细胞癌的肾门淋巴结转移率与PTEN阳性肾细胞癌的肾门淋巴结转移率比较 ,差异有显著性 (P <0 0 5 )。结论 :肾细胞癌中存在着抑癌基因PTEN的表达缺失和异常 ;抑癌基因PTEN的表达异常可能与肾细胞癌的发生、发展有关 ,抑癌基因PTEN是肾细胞癌的一种新的相关基因。 相似文献
73.
In order to confirm the role of 14-3-3 sigma (sigma) as a tumor suppressor in breast carcinogenesis, we have studied the expression of 14-3-3sigma immunohistochemically in usual ductal hyperplasia (UDH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) breast lesions. Immunostaining for estrogen receptor alpha (ERalpha), p53 and estrogen-responsive RING finger protein (Efp) was also carried out. Immunohistochemically, expression of 14-3-3sigma was seen in 92% UDH lesions and gradually decreased from 65% in DCIS to 23% in IDC. The expression of ERalpha decreased gradually from UDH to DCIS to IDC, while p53 showed an inverse staining pattern to that of ERalpha. The expression of Efp showed no significant difference among the three breast lesions. Hence, the present immunohistochemical study confirmed 14-3-3sigma as a tumor suppressor in breast carcinogenesis. A similar immunohistochemical analysis was then carried out on columnar cell hyperplasia with atypia (CCHA), in which the expression pattern of tumor suppressor 14-3-3sigma, ERalpha and p53 suggested that it might be possible that CCHA is a precancerous lesion. 相似文献
74.
〔摘要〕 妊娠高血压综合征(妊高征)产科常见的并发症,是引起孕产妇和围产儿死亡的主要原因之一,对其发病原因和机理尚不清楚。一般认为是由环境因素和遗传因素共同作用造成的,目前的研究热点是易感基因与妊高征的关系。本文对内皮型一氧化氮合酶(eNOS)基因和亚甲基四氢叶酸还原酶(MTHFR)基因多态性与妊高征发病的相关性进行了综述。 相似文献
75.
Nanda Navreet K.; Sercarz Eli E.; Hsu Di-Hwel; Kronenberg Mitchell 《International immunology》1994,6(5):731-737
We report that the lymphokines (IFN-) and IL-10 are co-syntheslzedby previously described CD3+ TCRß+, minor antigen-specificsuppressor T cell clones. IFN- and IL-10 are known to (I) becharacteristically produced by different helper T cell types,Th1 and Th2 respectively, and (II) inhibit the function of thereciprocal subset of T cells: IFN- Inhibits the function ofTh2 and IL-10 that of Th1 cells. Although Th0 cells are alsoknown to synthesize cytoklnes of both the Th1- and Th2-typeT cells, the suppressor T cells described in this report aredifferent from Th0 cells in that they produce (I) neither IL-2nor IL-4 molecules and (II) stimulation via their CD3-TCR systemseems independent of both IL-2 and IL-4, the typical autocrinemolecules for T cell proliferation. The lymphokine profile ofthese suppressor T (TJ cell clones, as well as those of humanantigen-specific T. cells reported earlier, suggests that co-synthesisof some Th1-llke and some Th2-like cytoklnes may be a characteristicof antigen-specific T, cells as opposed to the type of reciprocalinhibition mediated through IFN- or IL-10, which is antigennon-specific. 相似文献
76.
用空肠弯曲菌CJ—S131株感染昆明种小鼠3个月,观察到:(1)感染鼠血清中,出现高滴度的抗ds—DNA和ss—DNA抗体;(2)Con A诱导的抑制细胞功能降低和TH/Ts细胞比值增加;(3)PFC形成和LPS诱致的淋巴细胞转化作用增强:(4)DTH和Con A及PHA诱致的淋巴细胞转化作用增强。提示,CJ—S131感染小鼠使其T_S细胞功能降低,导致T_H细胞功能偏亢,B细胞功能亢进,这可能与自身免疫反应的产生有关。 相似文献
77.
Fiala C Aronsson A Granath F Stephansson O Seyberth HW Watzer B Gemzell-Danielsson K 《Human reproduction (Oxford, England)》2005,20(12):3414-3418
BACKGROUND: The pharmacokinetics of a novel slow-release (SR) misoprostol was studied and compared to conventional misoprostol. METHODS: Thirty-one women, pregnant between 8 and 12 weeks, requesting surgical abortion were randomly allocated to receive orally 400 microg conventional misoprostol, 400 microg SR misoprostol or 800 microg SR misoprostol. Venous blood samples were taken at 0, 30, 60, 120, 240 and 360 min after the administration of misoprostol. Misoprostol acid (MPA) was determined in serum samples using liquid chromatography/tandem mass spectrometry. RESULTS: Serum peak concentration (Cmax) was highest for conventional oral misoprostol. The time to peak concentration (Tmax) was similar for all groups. The area under the curve up to 360 min was similar for conventional and for 800 microg SR misoprostol and significantly greater for these groups compared to 400 microg SR misoprostol (P = 0.013). CONCLUSION: The new SR form of misoprostol demonstrated lower peak levels but longer-lasting elevation in plasma levels compared to conventional oral misoprostol. The AUC for 800 microg SR misoprostol was similar to that of 400 microg of conventional oral misoprostol. SR misoprostol may offer an alternative to repeated administration of oral misoprostol or to vaginal administration. 相似文献
78.
Characterization of a population of small macrophages in induced sputum of patients with chronic obstructive pulmonary disease and healthy volunteers 下载免费PDF全文
Frankenberger M Menzel M Betz R Kassner G Weber N Kohlhäufl M Häussinger K Ziegler-Heitbrock L 《Clinical and experimental immunology》2004,138(3):507-516
The inflammatory process in chronic obstructive pulmonary disease (COPD) is active mainly in the airways, but little is known about the properties of the inflammatory cells in this compartment. We have studied leucocytes in induced sputum of COPD patients compared to controls in order to uncover what types of macrophages might be involved in the disease. Sputum induction was performed by inhalation of nebulized sodium chloride solution. Leucocytes were isolated and stained with specific monoclonal antibodies for analysis in flow cytometry. Flow cytometry analysis revealed that a major portion of CD14+ macrophages in COPD has lower forward scatter, i.e. they are small macrophages. While in control donors these small macrophages accounted for 6.9% of all macrophages, the percentage of these cells in COPD was 45.7%. CD14 and HLA-DR expression was high on these small sputum macrophages while the large sputum macrophages expressed only low levels of these surface molecules, both in control donors and COPD patients. Small sputum macrophages of both control donors and COPD patients showed higher levels of constitutive tumour necrosis factor (TNF) compared to the large macrophages. TNF was inducible by lipopolysaccharide (LPS) preferentially in the small sputum macrophages in the control donors but there was no further induction in COPD patients. These data show that the small sputum macrophages are a major macrophage population in COPD and that these cells exhibit features of highly active inflammatory cells and may therefore be instrumental in airway inflammation in COPD. 相似文献
79.
Stopfer P Obermeier F Dunger N Falk W Farkas S Janotta M Möller A Männel DN Hehlgans T 《Clinical and experimental immunology》2004,136(1):21-29
The lymphotoxin-beta receptor (LTbetaR) pathway is critical for maintenance of organized lymphoid structures and is involved in the development of colitis. To investigate the mechanisms by which LTbetaR activation contributes to the pathology of chronic inflammation we used a soluble LTbetaR-Ig fusion protein as a competitive inhibitor of LTbetaR activation in the mouse model of chronic colitis induced by oral administration of dextran sulphate sodium. Strong expression of LTbeta which constitutes part of the LTalpha(1)beta(2) ligand complex was detected in colonic tissue of mice with chronic colitis. Treatment with LTbetaR-Ig significantly attenuated the development and histological manifestations of the chronic inflammation and reduced the production of inflammatory cytokines such as TNF, IL-1beta, and IL-6. Moreover, LTbetaR-Ig treatment significantly down-regulated mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression, leading to reduced leucocyte rolling and sticking in postcapillary and collecting venules and reduced extravasation into the intestinal mucosa as quantified by in vivo fluorescence microscopy. Thus, LTbetaR pathway inhibition ameliorates DSS-induced experimental chronic colitis in mice by MAdCAM-1 down-regulation entailing reduced lymphocyte margination and extravasation into the inflamed mucosa. Therefore, a combined treatment with reagents blocking T cell-mediated perpetuation of chronic inflammation such as LTbetaR-Ig together with direct anti-inflammatory reagents such as TNF inhibitors could constitute a promising treatment strategy for chronic colitis. 相似文献
80.
Since our previous experiments suggested that glycosylation-inhibiting factor (GIF) is a phosphorylated derivative of a phospholipase inhibitory protein, we determined whether other well-known phospholipase inhibitors may have similar biological activities. The results showed that phospholipase A2 (PLA2) inhibitors, such as recombinant human lipocortin I and ONO-RS-082, could switch T cell hybridoma 12H5 cells from the formation of glycosylated IgE-binding factors (IgE-BF) to the formation of unglycosylated IgE-BF, whereas neomycin, a phospholipase C inhibitor, failed to affect the nature of IgE-BF formed by the cells. The minimum concentrations of lipocortin I and ONO-RS-082 required for switching the 12H5 cells to the formation of unglycosylated IgE-BF were comparable to or less than IC50 of the inhibitors for PLA2. The ability of partially purified GIF to switch the 12H5 cells to the formation of unglycosylated IgE-BF was markedly enhanced by treatment of the preparation with alkaline phosphatase. It was also found that lipocortin I and ONO-RS-082, but not neomycin, facilitated the generation of GIF-producing T cells. When spleen cells of ovalbumin (OVA)-primed BDF1 mice were stimulated with homologous antigen and the activated T cells were propagated by recombinant IL-2 in the presence of GIF, lipocortin I, or ONO-RS-082, T cells obtained in the cultures constitutively produced their own GIF. Antigenic stimulation of the T cells induced the formation of unglycosylated IgE-BF and GIF with an affinity for OVA.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献