全文获取类型
收费全文 | 21593篇 |
免费 | 1635篇 |
国内免费 | 527篇 |
专业分类
耳鼻咽喉 | 182篇 |
儿科学 | 621篇 |
妇产科学 | 274篇 |
基础医学 | 4040篇 |
口腔科学 | 539篇 |
临床医学 | 1244篇 |
内科学 | 3662篇 |
皮肤病学 | 600篇 |
神经病学 | 1179篇 |
特种医学 | 287篇 |
外国民族医学 | 2篇 |
外科学 | 2582篇 |
综合类 | 2342篇 |
现状与发展 | 3篇 |
预防医学 | 978篇 |
眼科学 | 263篇 |
药学 | 2581篇 |
2篇 | |
中国医学 | 883篇 |
肿瘤学 | 1491篇 |
出版年
2023年 | 469篇 |
2022年 | 1033篇 |
2021年 | 1011篇 |
2020年 | 708篇 |
2019年 | 982篇 |
2018年 | 949篇 |
2017年 | 821篇 |
2016年 | 587篇 |
2015年 | 770篇 |
2014年 | 1004篇 |
2013年 | 1163篇 |
2012年 | 1072篇 |
2011年 | 1257篇 |
2010年 | 972篇 |
2009年 | 1035篇 |
2008年 | 939篇 |
2007年 | 927篇 |
2006年 | 889篇 |
2005年 | 859篇 |
2004年 | 803篇 |
2003年 | 670篇 |
2002年 | 482篇 |
2001年 | 399篇 |
2000年 | 420篇 |
1999年 | 292篇 |
1998年 | 267篇 |
1997年 | 286篇 |
1996年 | 219篇 |
1995年 | 210篇 |
1994年 | 209篇 |
1993年 | 160篇 |
1992年 | 115篇 |
1991年 | 111篇 |
1990年 | 79篇 |
1989年 | 76篇 |
1988年 | 72篇 |
1987年 | 51篇 |
1986年 | 50篇 |
1985年 | 170篇 |
1984年 | 183篇 |
1983年 | 110篇 |
1982年 | 146篇 |
1981年 | 123篇 |
1980年 | 122篇 |
1979年 | 111篇 |
1978年 | 101篇 |
1977年 | 63篇 |
1976年 | 56篇 |
1975年 | 40篇 |
1974年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
171.
本文研究三个价型六种盐对C_8-卵磷脂微团溶液的液-液相分离调控的规律,测定出各种加盐溶液的两相共存曲线,获得了各系统相变临界温度T_c随盐类型和盐离子强度变化的关系。用我们先前导出的关于盐对该微团溶液相变影响关系的方程式为T_c=T~0_c-A_1[I]~1.2+A_2[I]对本实验结果的拟合表明,这六种加盐微团溶液的液-液相分离亦遵从同样的变化规律。从而为揭示各种价型无机盐对两性离子化表面活性物质微团溶液液相分离的作用规律和机制提供了进一步的实验与理论依据。 相似文献
172.
白细胞介素-8研究进展 总被引:14,自引:0,他引:14
白细胞介素-8(IL-8)在趋化性细胞因子家族中属于C-X-C亚家族,IL-8是一个多种细胞来源的趋化性细胞因子,而且不同类型的细胞对不同的诱导剂的反应也不相同,因为由不同的实验室从不同的来源得到该因子,所以对于IL-8的许多不同的描述术语,对于IL-8的生理生化特性,目前已基本清楚,对于IL-8基因表达的调节,现认为主要是在转录水平的调控,并且发现其基因5′-侧翼区的AP-1,NF-кB及NF-IL-6结合位点是调节IL-8启动子功能的主要顺式作用元件,IL-8基因的表达需要这些元件之间高度的协同以达到有效的转录,IL-8受体则是一个由59KDa和67KDa亚单位组成的二聚体糖蛋白,存在于多种类型的细胞上,甚至包括一些不表达IL-8的细胞,IL-8的生物学活性并不表现出种族的特异性,IL-8可激活中性粒细胞,对T-淋巴细胞有趋化性并能刺激嗜碱性粒细胞,内皮细胞IL-8基因的表达除了受化学因子的调节外还受力学因素的影响,流体切应力诱导内皮细胞表达IL-8,可能在急性炎症和动脉粥样硬化的发生,发展过程中具有重要作用。 相似文献
173.
Over-expression of fibroblast growth factor 8 (FGF8) in human prostate cancer is associated with clinically aggressive disease. Among different members of the FGF family, FGF17 and FGF8 share high sequence homology and have similar patterns of expression during embryogenesis. In this study, the clinical significance of FGF17 expression and its in vitro function in prostate cancer cells were tested. Forty resected prostate specimens from patients with benign prostatic hyperplasia (BPH, n = 12) and prostate cancer (CaP, n = 28; Gleason sum scores 3-10) were studied using semi-quantitative RT-PCR. In addition, 85 cases of CaP (Gleason sum scores 5-9) and 20 cases of BPH were examined using immunohistochemistry and findings were correlated with clinical parameters. In vitro experiments using prostate cancer cell lines examined the functional significance of FGF17 in prostate cancer. These studies revealed a significant linear correlation between increasing Gleason sum scores and FGF17 expression using both immunohistochemistry (p < 0.0001, rho = 0.99) and RT-PCR (p = 0.008, rho = 0.99). Immunohistochemistry demonstrated upregulation of FGF17 in CaP compared with BPH (p < 0.0001) and, when comparing high-grade CaP (Gleason sum score 7-10) with BPH, RT-PCR showed a fourfold upregulation of FGF17 mRNA expression (p < 0.0001). Men with tumours displaying high levels of FGF17 expression had a worse outcome on survival analysis (p = 0.044) and a higher risk of progression with metastases (p < 0.0001). Proliferation assays showed low-dose recombinant (r) FGF17 (1 ng/ml) to be a more potent mitogen than rFGF1 and rFGF8 in prostate cancer cell lines (LNCaP, DU145, and PC3M) (p < 0.001). Furthermore, FGF8 was shown to induce expression of FGF17 in these cell lines. These data support a role for FGF17, and a model of co-expression of multiple FGFs, with FGF17 as a potential mediator of FGF8 function, in human prostate carcinogenesis. 相似文献
174.
目的:探讨p38蛋白激酶对LPS诱导大鼠肺泡巨噬细胞激活机制的作用。方法:提取细胞核蛋白,采用Western印迹分析p38蛋白激酶水平。用放射免疫法检测细胞上清TNF-α、IL-8的含量。结果:LPS显著增加肺泡巨噬细胞TNF-α、IL-8的合成,呈剂量依赖性诱导p38的活化。特异性p38蛋白激酶抑制剂SB203580能显著降低LPS诱导的肺泡巨噬细胞核蛋白p38的含量及细胞上清TNF-α、IL-8水平。结论:LPS刺激肺泡巨噬细胞释放炎性细胞因子TNF-α、IL-8受p38蛋白激酶调控。 相似文献
175.
目的:研究女性经前期复发性阿弗他溃疡(经前期RAU)患者血清中白细胞介素-6(IL-6)、白细胞介素-8(IL-8)、肿瘤坏死因子-α(TNF-α)和可溶性细胞间粘附分子-1(sICAM-1)的变化状况, 并探讨经前期RAU的发病机制。方法:用酶联免疫吸附双抗体夹心法(ELISA)检测女性经前期RAU患者外周血中IL-6、IL-8、TNF-α、sICAM-1的水平, 与正常对照组和无经前发作规律的女性RAU对照组相比。结果:经前期RAU患者的血清IL-6、IL-8、TNF-α水平不仅显著高于正常对照组(P<0.01), 而且高于女性RAU对照组(P<0.01)。而sICAM-1无明显变化。女性RAU患者血清中TNF-α亦高于正常对照组(P<0.05)。结论:经前期RAU患者体内存在IL-6、IL-8、TNF-α介导的免疫功能异常, 可能对RAU局部损害起作用。 相似文献
176.
Uchimura K Itoh M Yamamoto K Imamura S Makino M Kato T Fujiwara K Sawai Y 《Clinical and experimental immunology》2002,128(2):308-312
The possible roles of CD8+ cells in the abnormal T cell-dependent B-cell activation in Graves' disease were investigated by analysing lymphocyte subsets in peripheral blood mononuclear cells (PBMC) and their production of soluble factors and cytokines such as IL-10 in patients with Graves' disease, Hashimoto's thyroiditis and normal controls. The PBMC were separated into CD8+ and CD8-depleted cells by magnetic separation columns, and cultured for 7 days with or without anti-CD40 monoclonal antibodies and IL-4. The culture supernatant was assayed for sCD23 and IL-10 using EIA, and the remaining cells were analysed by flow cytometry. Stimulation with anti-CD40 antibody together with IL-4 increased sCD23 levels and the number of CD23+ cells. The latter was further augmented by depletion of CD8+ cells. This combination of B cell stimulants increased production of IL-10 by PBMC from patients with Graves' disease. The CD40- and IL-4-activated production of IL-10 was decreased by CD8+ cell depletion. In contrast, constitutive production of IL-10 was increased after CD8+ cell depletion in a group of patients with low basal secretion levels (<35 ng/ml). It was, however, decreased in a group with higher basal production levels, but such a relationship was not found in the normal control group. Thus, T cell-dependent B-cell activation via a CD40 pathway activates CD23+ cells, leading to over-production of IL-10 and a shift of the Th1/Th2 balance to Th2 dominance, while CD8+ cells may suppress this activation to counteract the Th2 deviation in Graves' disease. 相似文献
177.
Muda M He C Martini PG Ferraro T Layfield S Taylor D Chevrier C Schweickhardt R Kelton C Ryan PL Bathgate RA 《Molecular human reproduction》2005,11(8):591-600
LGR7 and LGR8 are G protein-coupled receptors that belong to the leucine-rich repeat-containing G-protein coupled receptor (LGR) family, including the thyroid-stimulating hormone (TSH), LH and FSH receptors. LGR7 and LGR8 stimulate cAMP production upon binding of the cognate ligands, relaxin and insulin-like peptide 3 (INSL3), respectively. We cloned several novel splice variants of both LGR7 and LGR8 and analysed the function of four variants. LGR7.1 is a truncated receptor, including only the N-terminal region of the receptor and two leucine rich repeats. In contrast, LGR7.2, LGR7.10 and LGR 8.1 all contain an intact seven transmembrane domain and most of the extracellular region, lacking only one or two exons in the ectodomain. Our analysis demonstrates that although LGR7.10 and LGR8.1 are expressed at the cell surface, LGR7.2 is predominantly retained within cells and LGR7.1 is partially secreted. mRNA expression analysis revealed that several variants are co-expressed in various tissues. None of these variants were able to stimulate cAMP production following relaxin or INSL3 treatment. Unexpectedly, we did not detect any direct specific relaxin or INSL3 binding on any of the splice variants. The large number of receptor splice variants identified suggests an unforeseen complexity in the physiology of this novel hormone-receptor system. 相似文献
178.
Amara RR Ibegbu C Villinger F Montefiori DC Sharma S Nigam P Xu Y McClure HM Robinson HL 《Virology》2005,343(2):246-255
Here, we study immune responses in four DNA/MVA-vaccinated macaques following an SHIV-89.6P challenge and a subsequent CD8 cell depletion. Both post-challenge and post-depletion peaks of viremia contracted with the expansion, or re-emergence, of CD8 T cells. Post-depletion, CD8 cells expanded in the presence of higher levels of neutralizing Ab and CD4 help than post-challenge and had superior maturational characteristics as measured by expression of the anti-apoptotic protein Bcl-2, the IL-7 receptor CD127 and co-production of IFN-gamma and IL-2. Pre-challenge and pre-depletion titers of neutralizing Ab correlated inversely with peaks of viremia and directly with peaks for anti-viral CD4 cells. Thus, our results reveal CD8 cells playing a central role, and neutralizing Ab, a supporting role in SHIV-89.6P control. They also suggest a dynamic relationship between neutralizing Ab, antigen load and anti-viral CD4 cells in the maturation of high-quality anti-viral CD8 T cells. 相似文献
179.
Buckner C Gines LG Saunders CJ Vojtech L Srivastava I Gettie A Bohm R Blanchard J Barnett SW Safrit JT Stamatatos L 《Virology》2004,320(1):167-180
The potential of vaccine-elicited anti-HIV envelope antibodies to control HIV-infection was evaluated by immunizing macaques with the HIV envelope protein and transiently depleting them of their CD8+ cells before intravenous challenge with the pathogenic CCR5-tropic SIV/HIV chimeric virus, SHIV(SF162P4). Although sterilizing immunity was not achieved, all vaccinated animals effectively controlled infection and remained free of disease for the duration of observation (over 3 years). In contrast, during the same period, the control animals progressed to disease. Both the vaccinees and the controls developed robust cell-mediated antiviral and neutralizing antibody responses following infection. A comparative analysis of these responses suggests that the more effective long-term control of infection by the vaccinated animals is due to the more rapid development of anti-HIV envelope antibodies. These studies suggest that priming by vaccination of B cell anti-HIV envelope responses maybe crucial for the long-term control of HIV infection. 相似文献
180.
Ara h 8, a Bet v 1-homologous allergen from peanut, is a major allergen in patients with combined birch pollen and peanut allergy 总被引:5,自引:0,他引:5
Mittag D Akkerdaas J Ballmer-Weber BK Vogel L Wensing M Becker WM Koppelman SJ Knulst AC Helbling A Hefle SL Van Ree R Vieths S 《The Journal of allergy and clinical immunology》2004,114(6):200-1417
BACKGROUND: We recently described patients with soybean allergy mainly mediated by cross-reactivity to birch pollen allergens. A majority of those patients were reported to have peanut allergy. OBJECTIVE: We sought to study the occurrence of peanut allergy in patients allergic to birch pollen and characterized the Bet v 1-homologous peanut allergen Ara h 8. METHODS: Recombinant Ara h 8 was cloned with degenerated primers and expressed in Escherichia coli. Nine Swiss and 11 Dutch patients with peanut and birch pollen allergy and a positive double-blind, placebo-controlled food challenge result to peanut were investigated for IgE reactivity to birch pollen and purified peanut allergens and cross-reactivity between birch and peanut. Ara h 8 stability against digestion and roasting was assessed by means of RAST inhibition. The IgE cross-linking potency of Ara h 8 was tested on the basis of basophil histamine release. RESULTS: During double-blind, placebo-controlled food challenge, all patients experienced symptoms in the oral cavity, progressing to more severe symptoms in 40% of patients. CAP-FEIA detected recombinant (r) Ara h 8-specific IgE in 85%. IgE binding to Ara h 8 was inhibited by Bet v 1 in peanut extract immunoblotting and in RAST inhibition. In EAST inhibition recombinant rAra h 8 inhibited IgE binding to peanut in 4 of 7 tested patient sera. Antipeanut response was dominated by Ara h 8 in 12 of 17 tested patients. Furthermore, our results demonstrate a low stability of Ara h 8 to roasting and no stability to gastric digestion. Basophil histamine release with rAra h 8 was more than 20% in 5 of 7 tested sera. CONCLUSIONS: Peanut allergy might be mediated in a subgroup of our patients by means of cross-reaction of Bet v 1 with the homologous peanut allergen Ara h 8. 相似文献