全文获取类型
收费全文 | 84045篇 |
免费 | 5881篇 |
国内免费 | 3781篇 |
专业分类
耳鼻咽喉 | 363篇 |
儿科学 | 1510篇 |
妇产科学 | 850篇 |
基础医学 | 13366篇 |
口腔科学 | 1691篇 |
临床医学 | 6969篇 |
内科学 | 14571篇 |
皮肤病学 | 1045篇 |
神经病学 | 8140篇 |
特种医学 | 1327篇 |
外国民族医学 | 15篇 |
外科学 | 5000篇 |
综合类 | 14091篇 |
现状与发展 | 22篇 |
预防医学 | 4921篇 |
眼科学 | 981篇 |
药学 | 10628篇 |
11篇 | |
中国医学 | 2589篇 |
肿瘤学 | 5617篇 |
出版年
2024年 | 180篇 |
2023年 | 893篇 |
2022年 | 2290篇 |
2021年 | 3093篇 |
2020年 | 2455篇 |
2019年 | 2125篇 |
2018年 | 2094篇 |
2017年 | 2394篇 |
2016年 | 2711篇 |
2015年 | 3058篇 |
2014年 | 5127篇 |
2013年 | 5761篇 |
2012年 | 5440篇 |
2011年 | 6053篇 |
2010年 | 4807篇 |
2009年 | 4668篇 |
2008年 | 4815篇 |
2007年 | 4660篇 |
2006年 | 4167篇 |
2005年 | 3932篇 |
2004年 | 3231篇 |
2003年 | 2741篇 |
2002年 | 2110篇 |
2001年 | 1817篇 |
2000年 | 1553篇 |
1999年 | 1340篇 |
1998年 | 1246篇 |
1997年 | 1083篇 |
1996年 | 940篇 |
1995年 | 749篇 |
1994年 | 715篇 |
1993年 | 610篇 |
1992年 | 519篇 |
1991年 | 492篇 |
1990年 | 414篇 |
1989年 | 323篇 |
1988年 | 318篇 |
1987年 | 303篇 |
1986年 | 281篇 |
1985年 | 400篇 |
1984年 | 348篇 |
1983年 | 241篇 |
1982年 | 268篇 |
1981年 | 218篇 |
1980年 | 175篇 |
1979年 | 119篇 |
1978年 | 99篇 |
1977年 | 80篇 |
1976年 | 71篇 |
1975年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
61.
62.
63.
硬膜外腔阻滞对胸部手术应激反应的影响 总被引:33,自引:1,他引:32
目的 观察硬膜外腔阻滞对胸部手术应激激素和细胞因子的影响。方法20例食管癌手术病人,随机分为两组,每组10例,即全麻复令硬膜外腔阻滞(GEA)组和全麻(GA)组,分别测定麻醉诱导前、手术2h、手术4h、术毕、术后1d及术后3d的血浆去甲肾上腺素、肾上腺素、血清促肾上腺皮质激素(ACTH)、皮质醇、C-反应蛋白、IL-6及IL-10的水平。结果 血浆去甲肾上腺素和血清皮质醇GEA组术中术后无显著改变,但GA组术毕和术后1d显著升高(P<0.05),术后3d恢复至术前水平,组间比较前者有显著差异(P<0.05)。两组血浆肾上腺素、IL-10术中术后均无显著变化。两组血清ACTH、IL-6及CRP术中术后均显著升高(P<0.05),组间比较无显著差异。结论 硬膜外腔阻滞可以减轻胸部手术的应激反应。IL-6是较CRP更灵敏的反映组织损伤的炎性指标。 相似文献
64.
Alexandra H. Heussner Evelyn O'Brien Daniel R. Dietrich 《Experimental and toxicologic pathology》2002,54(2):151-159
The mycotoxin ochratoxin A (OTA) is a potent renal carcinogen in rodents and induces renal fibrosis in pigs. Furthermore, OTA has been associated with the development of renal tumors and nephropathies in humans. Large species- and sex-differences are observed in sensitivity toward OTA-mediated toxicity and carcinogenicity, yet neither the mechanism(s) resulting in OTA toxicity nor the reasons for the observed species- and sex-specificities are known. This paper investigated variations in OTA handling viz binding to renal proteins which could possibly explain the observed differences in OTA susceptibility in vivo and in vitro. The results obtained via a modification of a standard receptor-binding assay demonstrated the presence of at least one homogeneous binding component in renal cortical homogenates from pig, mouse, rat and humans. This component was shown to bind OTA in a specific and saturable manner. A range of compounds selected for their affinity for steroid receptors and/or for various known organic anion transporters were employed in a competition assay to answer the question whether this homogenous OTA binding component represents a steroid-like receptor component or one of the known organic anion transporters of the kidney. Although many of the compounds were able to compete with OTA for protein-binding, the competition patterns displayed a distinct species specificity and did not correspond to the competition patterns associated with presently known organic anion transporters of the kidney in the mouse, rat or human. The data thus suggests the presence of a new organic anion transporter or more likely, a cytosolic binding component of unknown function with high affinity and capacity for OTA binding in humans, rats, mice and possibly pigs. 相似文献
65.
Gü l Gü rsel Haluk Tü rktas Nahide G k ora Ishak
zel Tekin 《The Journal of asthma》1997,34(4):313-319
The aim of the present study was to investigate whether sputum eosinophil cationic protein (ECP) concentrations could be a useful marker in the differential diagnosis between intrinsic asthma and chronic obstructive pulmonary disease (COPD). For this purpose total blood eosinophil counts were obtained and concentrations of serum and sputum ECP from 10 nonatopic asthmatics with a mild attack and 9 COPD patients with acute exacerbation were measured by radioimmunoassay. Mean serum ECP concentration was 54.3 ± 23.0 g/L in the asthmatic group and 83.3 ± 79.2 g/L in the COPD group (p: n.s.). In the group of asthmatics mean sputum ECP level was 984.5 ± 1245.5 mg/L/g sputum and in the COPD group it was 417.5 ± 363.5 mg/L/g sputum. There was no significant difference in sputum ECP levels between patients with asthma and COPD. We conclude that neither sputum nor serum ECP levels are useful markers in differential diagnosis of asthma attack and acute exacerbation of COPD. 相似文献
66.
SOLVEIG WÅLLBERG-JONSSON GÖSTA DAHLÉN OWE JOHNSON GUNILLA OLIVECRONA & SOLBRITT RANTAPÄÄ-DAHLQVIST 《Journal of internal medicine》1996,240(6):373-380
Objective. To evaluate the impact of chronic inflammation on lipoprotein lipase (LPL) levels and triglyceride metabolism in patients with rheumatoid arthritis (RA). Design. Plasma levels of LPL activity and mass before and after heparin were determined in post-menopausal women with active RA and in controls. The results were related to lipid levels and inflammatory variables. The LPL activity and mass together with triglyceride levels were also measured before and 6 h after an oral fat load. Setting. The study was performed on in- and out-patients at a University Rheumatology clinic. The controls came from the same reference area. Subjects. Altogether 17 consecutive post-menopausal female patients with RA and 16 age and sex matched controls were enrolled for the initial determination of LPL. Fifteen of the patients and 15 of the controls agreed to take part in the fat load. Of these, one patient and one control were excluded. Main outcome measures. LPL determination: basal levels and post-heparin levels of LPL activity and mass. Correlations between LPL and blood lipids (cholesterol, triglycerides), lipoprotein levels (high density lipoprotein, HDL; low density lipoprotein, LDL), erythrocyte sedimentation rate (ESR) acute phase proteins (orosomucoid, haptoglobin, fibrinogen mass) and cytokines (tumour necrosis factor α, TNF-α; interleukin 1β, IL-1β; and interleukin-6, IL-6). Fat tolerance test: LPL activity, mass and triglyceride levels before and 6 h after a per oral fat load. Results. Pre-heparin LPL mass (P<0.01) and activity (P<0.01) were significantly lower in the rheumatoid patients. Pre-heparin LPL mass showed no correlation to the lipid levels, but an inverse correlation to several inflammatory parameters; it was significant for orosomucoid (rs=?0.63, P<0.05) and C-reactive protein (CRP) (rs=?0.54, P<0.05) and close to significant for haptoglobin (rs=?0.48, P=0.087) and IL-6 (rs=?0.52, P=0.061). Six hours after a lipid load the LPL activity and mass were significantly lower in RA (P<0.05 and P<0.01, respectively) but the triglyceride level was not significantly different compared to controls. Conclusion. An inverse relationship exists between inflammatory status and pre-heparin LPL mass. Pre-heparin LPL mass reflects mainly the inactive monomeric fraction of LPL. This has been shown to hinder the uptake of remnant lipoprotein particles through competition with lipoprotein bound dimeric LPL for the LDL receptor-related protein (LRP receptor) on hepatocytes and macrophages in culture. A decrease of the level of monomeric LPL in plasma may thus be beneficial for remnant catabolism. The same mechanism may on the other hand increase macrophage uptake of lipids. This may not affect global lipid metabolism but may be important in driving the atherosclerotic process in the vessel wall. 相似文献
67.
ΔNp63蛋白在膀胱移行上皮癌中的表达及其临床意义 总被引:3,自引:1,他引:2
目的 :探讨 p5 3基因家族新成员截短型p6 3(△Np6 3)在膀胱癌组织中的表达及其意义。 方法 :采用免疫组织化学SP法检测 4 0例膀胱移行上皮癌 (TCC)、6例膀胱内翻性乳头状瘤和 8例正常膀胱移行上皮中△Np6 3的表达 ,并分析△Np6 3表达与膀胱癌病理类型、临床分期的关系。 结果 :正常膀胱移行上皮、膀胱内翻性乳头状瘤、TCC中△Np6 3的阳性表达率分别为 37.5 % (3/ 8)、6 6 .7% (4/ 6 )、10 0 % (40 / 4 0 ) ,组间差异有统计学意义 (P <0 .0 1)。TCCG3 级与G2 级△Np6 3的强阳性、中度阳性表达率显著高于G1级 (P <0 .0 1)。Ta~T1期以△Np6 3弱阳性为主 (6 6 .7% ) ,随TCC浸润程度的增加 ,△Np6 3染色强度逐渐增强。T2 期△Np6 3强阳性表达率为 35 .3% ,T3 ~T4期增至 6 3.6 %。结论 :△Np6 3在TCC中高表达 ,与TCC病理分级、临床分期密切相关 ;△Np6 3可能参与TCC的发生、发展 ,是评估TCC预后的潜在因素之一。 相似文献
68.
目的 将人乳头瘤病毒16型(Human papillomavirus type 16,HPV-16)的晚期表达蛋白E7上的抗原24肽(从第38位氨基酸到第61位氨基6病毒感染防治酸)与人免疫球蛋白G的重链恒定区融合表达,并以此融合蛋白作为抗原,可能为HPV-1提供免疫治疗方法。方法 利用PCR方法分别扩增HPV-16 E7(38-61)24肽的DNA片段和人免疫球蛋白G的重链恒定区DNA片段,并构建到pEV21a表达载体上,转化入E.coli中表达,利用SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和蛋白质免疫印迹(Western-blotting)的方法对表达结果进行鉴定。结果 构建的表达载体HPV16E7e/hIgGHCCR-pET21a经酶切鉴定和测序显示序列正确;通过SDS-PAGE和Western-blotting的鉴定,重组融合蛋白Mr约40000,表达量可占菌体蛋白的20%左右。结论 成功构建HPV16-E7的抗原多肽片段和人免疫球蛋白G的重链恒定区的融合蛋白,并可在E.coli中高效表达。 相似文献
69.
目的 :探讨白细胞介素 2 (IL 2 )对垂体瘤细胞系RC 4B/C细胞ACTH分泌的调控作用及其影响因素 .方法 :以放射免疫方法测定培养的垂体瘤细胞系RC 4B/C细胞的培养液中的ACTH浓度 .结果 :IL 2 (1× 10 4~ 5× 10 5U·L-1)促进RC 4B/C细胞分泌ACTH ;蛋白激酶A的抑制剂H 9(1μmol·L-1)和酪氨酸蛋白激酶的抑制剂tyrphostin2 3 (1μmol·L-1)均可显著性抑制IL 2的促ACTH分泌作用 .结论 :IL 2可促进RC 4B/C细胞分泌ACTH ,该作用与蛋白激酶A和酪氨酸蛋白激酶信号转导途径紧密相关 相似文献
70.
[目的]研究大豆蛋白对肾损害大鼠钙平衡的影响。[方法]选择3月龄断乳雄性SD大鼠40只.按体质量从小到大排序,采用完全随机化原则分为4组。每组10只。标准饲料对照组:喂食含有14%酪蛋白饲料;大豆蛋白饲料组:喂食含有14%大豆分离蛋白饲料;混合饲料1组:喂食含有7%酪蛋白加7%大豆分离蛋白饲料;混合饲料2组:喂食含有7%酪蛋白加14%大豆分离蛋白饲料。实验期用腺嘌呤灌胃共21d,建立肾损害大鼠模型,各组大鼠喂养相应饲料6周,测饲料消耗量、24h尿蛋白、尿钙、钙表观吸收率、储留钙量。[结果]4组实验大鼠饲料摄入量1d~30d无统计学差异,大豆蛋白饲料组和混合饲料1组实验结束时与另外两组相比,尿钙排泄量低,钙表观吸收率和储留钙量高,差异有统计学意义(P〈0.05)。[结论]蛋白质含量水平在14%条件下,含大豆蛋白的两种饲料对肾损害大鼠钙吸收、钙排泄的影响无统计学差异,有利于促进钙吸收,减少钙排泄。 相似文献