全文获取类型
收费全文 | 26446篇 |
免费 | 3245篇 |
国内免费 | 977篇 |
专业分类
耳鼻咽喉 | 240篇 |
儿科学 | 600篇 |
妇产科学 | 416篇 |
基础医学 | 3603篇 |
口腔科学 | 722篇 |
临床医学 | 2758篇 |
内科学 | 4456篇 |
皮肤病学 | 284篇 |
神经病学 | 1731篇 |
特种医学 | 1059篇 |
外科学 | 4798篇 |
综合类 | 3210篇 |
一般理论 | 5篇 |
预防医学 | 2048篇 |
眼科学 | 376篇 |
药学 | 1799篇 |
8篇 | |
中国医学 | 846篇 |
肿瘤学 | 1709篇 |
出版年
2024年 | 133篇 |
2023年 | 488篇 |
2022年 | 844篇 |
2021年 | 911篇 |
2020年 | 917篇 |
2019年 | 1375篇 |
2018年 | 1912篇 |
2017年 | 851篇 |
2016年 | 781篇 |
2015年 | 820篇 |
2014年 | 1675篇 |
2013年 | 1630篇 |
2012年 | 1412篇 |
2011年 | 1662篇 |
2010年 | 1342篇 |
2009年 | 1376篇 |
2008年 | 1428篇 |
2007年 | 1388篇 |
2006年 | 1167篇 |
2005年 | 1231篇 |
2004年 | 894篇 |
2003年 | 710篇 |
2002年 | 628篇 |
2001年 | 444篇 |
2000年 | 568篇 |
1999年 | 508篇 |
1998年 | 454篇 |
1997年 | 315篇 |
1996年 | 276篇 |
1995年 | 215篇 |
1994年 | 263篇 |
1993年 | 261篇 |
1992年 | 332篇 |
1991年 | 135篇 |
1990年 | 206篇 |
1989年 | 80篇 |
1988年 | 168篇 |
1987年 | 113篇 |
1986年 | 103篇 |
1985年 | 107篇 |
1984年 | 101篇 |
1983年 | 51篇 |
1982年 | 84篇 |
1981年 | 32篇 |
1980年 | 47篇 |
1979年 | 36篇 |
1978年 | 20篇 |
1977年 | 33篇 |
1976年 | 40篇 |
1974年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
We reviewed ninety-three patients who had one hundred and seven complete fractures of the femur between them and were treated over a twenty-five year period in Western Australia and South Australia. Operative surgical management of complete fractures in the middle and distal thirds was usually successful. In contrast, fractures proximal to the middle third were regularly associated with non-union, implant failure and requirement for revision surgery. In view of this significant difference in outcome after fracture of the pagetic femur in different sites, a comprehensive surgical management strategy is recommended in order to avoid complications. 相似文献
52.
目的 :研究低氧对体外培养的口腔鳞癌细胞系血管内皮生长因子 (vascularendothelialgrowthfactor ,VEGF)和明胶酶 A(matrixmetalloproteinase 2 ,MMP 2 )的影响。 方法 :分别用酶联免疫吸附实验 (ELISA)和半定量逆转录聚合酶链反应 (RT PCR)测定了低氧处理不同时间段时口腔鳞癌细胞系TSCCa和GNM细胞的细胞中VEGF和MMP 2的活性和mRNA表达情况。结果 :低氧处理 4h时 ,VEGF和MMP 2的活性便显著增加 ,8h时达到最高 ,GNM细胞中VEGF和MMP 2分别增加 2倍和 2 .5倍 ;而TSCCa细胞中VEGF和MMP 2增加的更为明显 ,分别增加了 6倍和 4倍。RT PCR结果显示GNM细胞VEGF和MMP 2mRNA表达水平均较TSCCa细胞高 (P <0 .0 5 ) ,低氧处理时在TSCCa细胞中VEGF和MMP 2增加的尤为明显。结论 :低氧可通过调节口腔鳞癌细胞VEGF和MMP 2的活性和mRNA的表达在口腔鳞癌血管形成中起重要作用 相似文献
53.
公伟宏 《华北煤炭医学院学报》2003,5(2):137-138
目的:评价太极通天液治疗血管性痴呆的临床疗效。方法:随机将148例血管性痴呆分为太极通天液治疗组和丹参口服液对照组,另接应用韦氏成人智力量表评分,将血管性痴呆组分为3个亚组:即80-89分组,70-79分组和70分以下组,观察期为3个月。结果:太极通天液治疗前后WAIS-RC评分与对照组比较,80-89分组和70-79分组均有统计学差异(P<0.05),而70分以下组无统计学差异(P>0.05),结论:太极通天液对血管性痴呆有较好的治疗效果,且与痴呆病情程度有关。 相似文献
54.
55.
Lung cancer mortality rates among United States and Japanese males were compared and related to smoking and dietary data. Mortality rates increased from 1950 to 1985 in both countries, but the absolute values are consistently lower in Japan (38.2 deaths/100,000 in 1985) than in the U.S. (72.2/100,000). The proportion of smokers is higher in Japan than in the U.S. since 1955. Japanese males start smoking considerably later than U.S. males, but smoke a higher quantity of cigarettes per day. Available information on inhalation practices and yield and type of cigarettes smoked showed no differences among the two countries large enough to account for the differences in mortality rates. Further data in this regard should he obtained. Dietary data show that fat consumption (as percentage of calories) is consistently higher in the U.S. than in Japan from 1950 (40% vs. 7.9%) through 1985 (43.5% vs. 24.5%). A linear relationship is observed between lung cancer mortality and fat intake. Our data support the hypothesis that dietary habits may modulate the carcinogenic effects of tobacco smoking. 相似文献
56.
In multiple sclerosis (MS) up-regulation of β-adrenoceptors on peripheral blood mononuclear cells (PBMCs) has been attributed to either autonomic dysfunction, inflammation or a combination of the two. We have compared secondary progressive MS patients with normal subjects (NS) and two models of autonomic dysfunction; pure autonomic failure (PAF) and multiple system atrophy (MSA, Shy-Drager syndrome). There was up-regulation of β-adrenoceptors on PBMCs in MS and PAF patients but not in MSA patients. Only in PAF patients β-adrenoceptor up-regulation was correlated with low plasma levels of noradrenaline (NA) and adrenaline (Ad). In addition to studies in the basal state, measurements also were made after the centrally acting sympatholytic agent clonidine. These were combined with haemodynamic and neurohormonal measurements. After clonidine, there was a fall in blood pressure in NS and MSA patients but not in MS and PAF patients; a rise in growth hormone (GH) in NS and PAF patients but not in MS and MSA patients; and an up-regulation in PBMCs β-adrenoceptors in NS but not in MS, MSA and PAF patients. Up-regulation of β-adrenoceptors on PBMCs in MS could be attributed to autonomic dysfunction but the disparity between MS and PAF patients when considering their plasma levels of NA and Ad argue against. Although the neurohormonal responses to clonidine and the physiological assessment of autonomic function in progressive MS patients, demonstrate central autonomic dysfunction resembling that of the MSA patients, the normal basal β-adrenoceptor densities in the latter, suggests that the up-regulation of these receptors is independent of the central autonomic dysfunction in MS. 相似文献
57.
Summary The effectiveness of nifedipine retard as a treatment for Raynaud's phenomenon was assessed in 15 patients in a placebo controlled double blind study. An associated connective tissue disease was evident in 7 patients. Changes in finger and forearm blood flow (venous occlusion plethysmography), digital skin temperature and digital systolic pressure were measured acutely before and after a 2-week treatment period. Subjective assessment of efficacy was based on patient diary data. In addition alpha2-adrenoceptor density on platelets was measured before and after chronic nifedipine therapy in both the patient group and in an age-and-sex-matched control group. No significant haemodynamic changes were observed. Nifedipine retard significantly reduced the frequency (p<0.05) with no change in either the duration or severity of vasospastic attacks. Side effects were commono following nifedipine retard. A reduction in alpha2-adrenoceptor density on platelets was observed in patients compared to a control group (p<0.05). Alpha2-adrenoceptor density was unchanged following a 2-week treatment period with nifedipine retard. This study concludes that nifedipine retard is not effective in the treatment of Raynaud's phenomenon over a short time course. Patients with Raynaud's phenomenon have reduced alpha2-adrenoceptor densities on their platelets. 相似文献
58.
米非司酮作用于兔输卵管收缩活动与Ca^2+关系的研究 总被引:1,自引:0,他引:1
通过“结合化学分离与原子吸收分光光度法”对Ca^2 含量测定和离体输卵管肌条收缩记录方法,研究米非司酮(Ru486)对增加假孕(4d)兔输卵管平滑肌收缩频率,而不改变其收缩张力和振幅时与Ca^2 之间的关系,结果提示:(1)Ru486对输卵管分泌液和组织内Ca^2 的含量分布无明显影响;(2)Ru486具有降低细胞外液高Ca^2 浓度促Ca^2 内流,而使收缩增强的效应,且能协同Ca^2 通道阻断剂(Verapamil)抑制细胞外Ca^2 内流,而致收缩减弱的效应。 相似文献
59.
Anti-tumor necrosis factor (TNF) antibodies inhibit passively transferred experimental allergic encephalomyelitis (EAE) in SJL mice. The possibility that this occurs through interference in TNF's upregulation of endothelial cell adhesion molecules was investigated. Expression of both vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) on spinal cord vessels increased during EAE. The upregulation of VCAM-1 was markedly reduced or prevented by anti-TNF treatment. Leukocytic infiltration was 15-fold lower in anti-TNF-treated than diseased animals. Spinal cord endothelial expression of VCAM-1, though not ICAM-1 or fibronectin, positively correlated with the extent of T cell, B cell or monocyte infiltration in each animal. 相似文献
60.