全文获取类型
收费全文 | 25691篇 |
免费 | 2716篇 |
国内免费 | 1737篇 |
专业分类
耳鼻咽喉 | 168篇 |
儿科学 | 282篇 |
妇产科学 | 227篇 |
基础医学 | 3059篇 |
口腔科学 | 458篇 |
临床医学 | 3746篇 |
内科学 | 3585篇 |
皮肤病学 | 282篇 |
神经病学 | 1282篇 |
特种医学 | 856篇 |
外国民族医学 | 18篇 |
外科学 | 2488篇 |
综合类 | 4865篇 |
现状与发展 | 6篇 |
预防医学 | 1388篇 |
眼科学 | 619篇 |
药学 | 2966篇 |
47篇 | |
中国医学 | 1579篇 |
肿瘤学 | 2223篇 |
出版年
2024年 | 165篇 |
2023年 | 629篇 |
2022年 | 1586篇 |
2021年 | 1877篇 |
2020年 | 1404篇 |
2019年 | 1078篇 |
2018年 | 1120篇 |
2017年 | 983篇 |
2016年 | 909篇 |
2015年 | 1347篇 |
2014年 | 1624篇 |
2013年 | 1340篇 |
2012年 | 1880篇 |
2011年 | 1998篇 |
2010年 | 1172篇 |
2009年 | 894篇 |
2008年 | 1161篇 |
2007年 | 1103篇 |
2006年 | 1125篇 |
2005年 | 1084篇 |
2004年 | 717篇 |
2003年 | 639篇 |
2002年 | 552篇 |
2001年 | 494篇 |
2000年 | 521篇 |
1999年 | 523篇 |
1998年 | 313篇 |
1997年 | 307篇 |
1996年 | 214篇 |
1995年 | 206篇 |
1994年 | 221篇 |
1993年 | 116篇 |
1992年 | 128篇 |
1991年 | 127篇 |
1990年 | 124篇 |
1989年 | 90篇 |
1988年 | 86篇 |
1987年 | 77篇 |
1986年 | 61篇 |
1985年 | 57篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 3篇 |
1979年 | 15篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
This investigation was made with reference to the changes of serum angiotensin converting enzyme (SACE) activity in type 2 diabetes and its vascular complications. SACE activity was studied in 127 type 2 diabetic patients and 90 healthy persons by using a spectrophotometric assay. The results showed SACE activity was obviously higher in diabetic patients (459.51 +/- 175.85 U) than in healthy persons (321.14 +/- 121.27 U); SACE activity was significantly higher in type 2 diabetic patients with diabetic nephropathy (548.27 +/- 166.60 U) than in patients without diabetic nephropathy (383.2 +/- 139.00 U), but there was no difference between patients with microalbuminuria and macroalbuminuria; no statistical difference was detected in SACE activity between diabetic patients with diabetic retinopathy (465.64 +/- 178.93 U) and without retinopathy (449.07 +/- 170.04 U); SACE activity was not associated with the course of diabetes, blood pressure, blood lipid and blood glucose. These data suggest that raised SACE activity might only play a role in the initiation of type 2 diabetes and diabetic nephropathy, but not relate to the progress of diabetic nephropathy, the onset of diabetic retinopathy and hypertension. 相似文献
42.
脑外伤后脑干组织中血管内皮细胞及血浆蛋白分布改变的免疫?… 总被引:1,自引:0,他引:1
目的:探讨脑外伤后脑干组织中血脑屏障和神经细胞的病理学改变.方法:采用免疫组化染色显示人体脑干组织中的血管内皮细胞(CD31)和某些血浆蛋白(白蛋白及 IgM).结果:1.在正常脑干组织中, CD31阳性物呈连续的线条状,围成规则的血管腔,其周围无明显间隙;血浆蛋白位于血管内,未见到血浆/蛋白阳性神经细胞或神经纤维.2.脑外伤后,脑干中的 CD31阳性物呈不规则弯曲的小片段状,围成不规则的血管腔,其周围间隙明显增宽;同时可见到白蛋白及IgM阳性神经细胞和神经纤维.结论:脑外伤后,脑干组织中的血脑屏障受到了破坏,而且神经细胞也有不同程度的损伤. 相似文献
43.
Yi-Fei Zhang Jing-Jing Guo Fan Yang Hang-Yu Zhou Na-Na Zhang Xiao-Chuan Xiong Yue Feng Yong-Qiang Deng Cheng-Feng Qin 《Journal of medical virology》2023,95(1):e28290
The geographic range of Zika virus (ZIKV) has expanded from Asia to the Americas, leading to the 2015–2016 pandemic with enhanced neurovirulence. At present, ZIKV is continuously circulating in many Southeast Asian countries. Unfortunately, the persistent evolution of ZIKV in Southeast Asia and its influence on the biological characteristics of the virus remain incompletely understood. In this study, the in vitro and in vivo properties of a new ZIKV isolate obtained from Cambodia in 2019 (CAM/2019) were characterized and compared with those of the Cambodian strain (CAM/2010). Compared with CAM/2010, the CAM/2019 virus showed similar plaque morphology and growth curves in cell cultures and induced comparable viremia and organ viral loads profiles in both BALB/c and A129 (IFNAR1−/−) mice upon intraperitoneal (i.p.) inoculation. Remarkably, the CAM/2019 virus exhibited enhanced neurovirulence in neonatal mice compared with CAM/2010, with a 74-fold reduction in the 50% lethal dose (LD50). Consistently, CAM/2019 produced higher viral loads in the brains of BALB/c neonatal mice than CAM/2010 did. Sequence alignment showed that the CAM/2019 virus has acquired 12 amino acid substitutions, several of which were found to be associated with neurovirulence. In particular, the CAM/2019 virus shared an A1204T substitution in NS2A with the Thai isolate SI-BKK02 that was isolated from a microcephaly case. Taken together, our results indicate that a ZIKV strain isolated with specific mutations has emerged in Cambodia, highlighting the need for extensive molecular and disease surveillance in Cambodia and other Asian countries. 相似文献
44.
目的:探讨外周动静脉同步换血对血清钙的影响。方法:对25全高胆红素血症患儿采用同型血进行外周动静脉同步换血,换血前后在同一动脉端取血测血清钙。结果:换血过程中应用钙剂组(观察组)与未应用钙剂组,血钙水平在换血前后及两组之间均无差异,P〉0.05。注射钙剂的不良反应发生率为6.25%。结论:外周动静脉同步换血疗法对血清钙无明显影响,换血过程中静注钙剂是不必要的。 相似文献
45.
目的 探索不健康行为生活方式与高尿酸血症的关系,以及高血压、血脂异常的效应修饰作用,为预防高尿酸血症提供理论依据。方法 采用横断面调查研究设计,基于2021年10-12月来自四川省、贵州省28个地级市和重庆市33个区(县)中国铁路成都局集团有限公司的西南职业人群队列基线数据,通过问卷调查、体格测量及实验室生化检测收集研究对象的人口学特征、行为生活方式、慢性非传染性疾病患病情况。不健康行为生活方式得分根据吸烟、饮酒、膳食模式、体力活动和低体重/超重状况进行评分,分值越高不健康行为生活方式越多。采用多因素logistic回归模型分析不健康行为生活方式评分、吸烟状况、饮酒状况等与高尿酸血症的关系,采用分层分析探索高血压等疾病对不健康行为生活方式与高尿酸血症之间关系的修饰效应。结果 共纳入11 748名研究对象,高尿酸血症患病率为34.4%。多因素logistic回归分析显示,现在吸/既往吸烟、现在饮/既往饮酒及BMI异常是高尿酸血症患病的危险因素,不健康行为生活方式对高尿酸血症患病风险呈现累积效应,随着得分的升高,高尿酸血症患病风险升高,OR值由1.64(95%CI:1.34~2.00)上升至2.89(95%CI:2.39~3.50)。分层分析结果显示,在高血压及血脂异常人群中,不健康行为生活方式对高尿酸血症患病风险影响更大。结论 多种不健康行为生活方式的共存会升高高尿酸血症患病风险,这一效应在高血压、血脂异常人群中更明显。及时纠正不健康行为生活方式,并控制高血压和血脂异常,降低患高尿酸血症的风险。 相似文献
46.
目的:探讨退变性腰椎管狭窄症的手术治疗。方法:对94例60岁以上患者进行分型和手术治疗。结果:将本病分为Ⅰ型(侧隐窝狭窄型);Ⅱ型(中央管狭窄型);Ⅲ型(混合型)。对Ⅰ型手术方式采用单侧或双侧椎板开窗,扩大神经根管或(和)摘除髓核;对Ⅱ型行半椎板或全椎板切除术;对Ⅲ型行全椎板切除术。结论:通过术后疗效观察和3年随访,根据分型的不同选择不同的手术方式,可达到较好的临床疗效 相似文献
47.
48.
The accumulated evidence suggests that the overproduction of nitric oxide (NO) is involved in methamphetamine (METH)-induced neurotoxicity. Using NADPH-diaphorase histochemistry, neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) antibody immunohistochemistry, the possible overexpression of nNOS and iNOS was investigated in the brains of mice treated with METH. The number of positive cells or the density of positive fibers was assessed at 1 h, 24 h and 1 week after METH injections. There were no clear positive iNOS cells and fibers demonstrated in the brains of mice after METH treatment. In contrast, METH caused marked increases in nNOS in the striatum and hippocampus at 1 and 24 h post-treatment. The nNOS expression normalized by 1 week. There were no statistical changes in nNOS expression in the frontal cortex, the cerebellar cortex, nor in the substantia nigra. These results provide further support for the idea that NO is involved in the neurotoxic effects of METH. 相似文献
49.
Zhou XF Deng YS Chie E Xue Q Zhong JH McLachlan EM Rush RA Xian CJ 《The European journal of neuroscience》1999,11(5):1711-1722
Injury to a peripheral nerve induces in the dorsal root ganglia (DRG) sprouting of sympathetic and peptidergic terminals around large-diameter sensory neurons that project in the damaged nerve. This pathological change may be implicated in the chronic pain syndromes seen in some patients with peripheral nerve injury. The mechanisms underlying the sprouting are not known. Using in situ hybridization and immunohistochemical techniques, we have now found that nerve growth factor (NGF) and neurotrophin-3 (NT3) synthesis is upregulated in satellite cells surrounding neurons in lesioned DRG as early as 48 h after nerve injury. This response lasts for at least 2 months. Quantitative analysis showed that the levels of mRNAs for NT3 and NGF increased in ipsilateral but not contralateral DRG after nerve injury. Noradrenergic sprouting around the axotomized neurons was associated with p75-immunoreactive satellite cells. Further, antibodies specific to NGF or NT3, delivered by an osmotic mini-pump to the DRG via the lesioned L5 spinal nerve, significantly reduced noradrenergic sprouting. These results implicate satellite cell-derived neurotrophins in the induction of sympathetic sprouting following peripheral nerve injury. 相似文献
50.