全文获取类型
收费全文 | 34843篇 |
免费 | 2404篇 |
国内免费 | 1453篇 |
专业分类
耳鼻咽喉 | 197篇 |
儿科学 | 263篇 |
妇产科学 | 55篇 |
基础医学 | 1857篇 |
口腔科学 | 57篇 |
临床医学 | 4784篇 |
内科学 | 13570篇 |
皮肤病学 | 59篇 |
神经病学 | 389篇 |
特种医学 | 1631篇 |
外科学 | 1641篇 |
综合类 | 7584篇 |
现状与发展 | 1篇 |
预防医学 | 965篇 |
眼科学 | 41篇 |
药学 | 3796篇 |
26篇 | |
中国医学 | 1719篇 |
肿瘤学 | 65篇 |
出版年
2024年 | 68篇 |
2023年 | 413篇 |
2022年 | 797篇 |
2021年 | 1231篇 |
2020年 | 1161篇 |
2019年 | 986篇 |
2018年 | 951篇 |
2017年 | 838篇 |
2016年 | 908篇 |
2015年 | 980篇 |
2014年 | 2053篇 |
2013年 | 2253篇 |
2012年 | 1702篇 |
2011年 | 1994篇 |
2010年 | 1692篇 |
2009年 | 1574篇 |
2008年 | 1706篇 |
2007年 | 1827篇 |
2006年 | 1760篇 |
2005年 | 1499篇 |
2004年 | 1307篇 |
2003年 | 1191篇 |
2002年 | 1032篇 |
2001年 | 1104篇 |
2000年 | 911篇 |
1999年 | 829篇 |
1998年 | 736篇 |
1997年 | 687篇 |
1996年 | 552篇 |
1995年 | 490篇 |
1994年 | 469篇 |
1993年 | 371篇 |
1992年 | 311篇 |
1991年 | 302篇 |
1990年 | 249篇 |
1989年 | 202篇 |
1988年 | 206篇 |
1987年 | 191篇 |
1986年 | 157篇 |
1985年 | 200篇 |
1984年 | 173篇 |
1983年 | 105篇 |
1982年 | 116篇 |
1981年 | 93篇 |
1980年 | 71篇 |
1979年 | 60篇 |
1978年 | 50篇 |
1977年 | 43篇 |
1976年 | 35篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
本文测定了第1-7天急性心梗塞患者红细胞磷脂主要组分含量。结果表明,急性心肌梗塞患者红细胞膜的神经鞘磷含量较正常人明显增高;磷酯酰胆硷,磷脂酰丝氨酸、磷脂酰乙醇胺含量却较正常人明显降低。这说明急性心肌梗塞患者存在红细胞磷脂代谢紊乱,这时心肌缺血的重可能产生不良影响。 相似文献
72.
兔心肌挫伤心功能障碍与心肌细胞内Ca2+和线粒体ATP酶的变化 总被引:2,自引:1,他引:1
目的:探讨心肌细胞内游离钙([Ca^2 ]i)和心肌ATP酶变化在心肌挫伤(MC)后心功能障碍发生机制中的意义。方法:随机选取兔36只,分为6组:正常对照、伤后2、4、8、12、24h,每组6只。经右颈总动脉插管至左心室测左室压力。采用BIM-II型生物撞击机致成MC模型。在上述时相点测定左室压力,并测定心肌细胞内[Ca^2 ]i和心肌匀浆组织及线粒体ATP酶活力。结果:心脏收缩/舒张功能受到损害,心肌细胞内[Ca^2 ]i升高,心肌匀浆组织及线粒体ATP酶下降,相关分析表明心功能障碍与心肌细胞内[Ca^2 ]i含量升高呈明显负相关,与ATP酶活性降低呈明显正相关。结论:MC后心脏功能下降,心肌细胞内[Ca^2 ]i含量升高和ATP酶活性下降可能是其原因之一。 相似文献
73.
HIDEKI TASHIRO M.D. SAMON KOYANAGI M.D. AKIRA TAKESHITA M.D. 《Echocardiography (Mount Kisco, N.Y.)》1993,10(4):343-350
To elucidate the pathogenesis of mitral regurgitation (MR) after myocardial infarction (MI), the incidence of papillary muscle dysfunction (PMD), mitral annular size, and the extent of wall-motion abnormalities were examined in 81 patients with previous MI by two-dimensional echocardiography and real-time two-dimensional Doppler flow imaging. The prevalence of pathological MR was lower in patients with anterior MI (36%) than in those with inferior (65%) or anterior and inferior MI (88%) (P < 0.01 vs anterior MI group). The incidence of PMD in patients with MR in the anterior MI group (15%) was lower than that in the inferior (50%, P < 0.01) or anterior and inferior MI group (43%, P < 0.05). The mitral annular dimension in patients with MR was significantly greater than in those without MR, but it was similar among the three groups. The extent of wall-motion abnormality correlated significantly with the area of MR jet in the anterior MI group (y = 3.1x + 15.5, r = 0.52, P < 0.01) and in the inferior MI group (y = 8.3x + 32.7, r = 0.57, P < 0.01). However, the slope of this relationship was significantly steeper in the inferior MI group than in the anterior MI group (P < 0.05). These results indicated that the degree of MR with inferior MI was greater than with anterior MI for a given MI area. PMD may play an important role in the higher prevalence and greater degree of MR in inferior MI. 相似文献
74.
75.
76.
77.
Janus激酶转导和转录活化因子(Stat3)在Goldblatt鼠左室肥厚心肌中的变化以及缬沙坦干预后的变化 总被引:2,自引:0,他引:2
《高血压杂志》2004,12(6):542-546
78.
目的探讨国产前列腺内支架治疗前列腺增生引起排尿困难的疗效及并发症.方法42例前列腺增生引起的排尿困难的患者,置入46枚前列腺内支架.支架均为国产镍钛记忆合金编织而成.结果42例患者中,36例置入支架后立即自行排尿,5例因前列腺增生过大前列腺尿道部过长或支架位置不理想,置入一个支架,排尿仍有困难,再次置入第二个支架后,立即自行排尿,但2例出现长期的尿失禁;1例伴有糖尿病的患者,置入支架1周后排尿困难未改善,而进行外科手术治疗.36例生活质量积分0~3分,29例术后随访6~21个月,国际前列腺症状评分(I-PSS)术前27.49±4.21,术后6.89±3.76(P<0.001),最大尿流率术前(1.78±3.89)ml/s,术后(13.91±3.56)ml/s(P<0.001).结论国产前列腺支架治疗前列腺增生引起的排尿困难虽然会出现一些并发症,但仍是一种安全、可靠的方法. 相似文献
79.
Catherine Chapon Laurent Lemaire Florence Franconi Laurent Marescaux Pierre Legras Benoit Denizot Jean-Jacques Le Jeune 《Magnetic resonance in medicine》2004,52(4):932-936
The aim of this study was to detect salvageable peri-infarction myocardium by MRI in rats after infarction, using with a double contrast agent (CA) protocol at 7 Tesla. Intravascular superparamagnetic iron oxide (SPIO) nanoparticles and an extracellular paramagnetic CA (Gd-DOTA) were used to characterize the peri-infarction zone, which may recover function after reperfusion occurs. Infarcted areas measured from T1-weighted (T1-w) images post Gd-DOTA administration were overestimated compared to histological TTC staining (52% +/- 3% of LV surface area vs. 40% +/- 3%, P=0.03) or to T2-w images post SPIO administration (41% +/- 4%, P=0.04), whereas areas measured from T2-w images post SPIO administration were not significantly different from those measured histologically (P=0.7). Viable and nonviable myocardium portions of ischemically injured myocardium were enhanced after diffusive Gd-DOTA injection. The subsequent injection of vascular SPIO nanoparticles enables the discrimination of viable peri-infarction regions by specifically altering the signal of the still-vascularized myocardium. 相似文献
80.
Prevalence of silent myocardial ischemia in asymptomatic individuals with subclinical atherosclerosis detected by electron beam tomography 总被引:3,自引:0,他引:3
Anand D. Vijay Lim Eric Raval Usha Lipkin David Lahiri Avijit 《Journal of nuclear cardiology》2004,11(4):450-457
BACKGROUND: Electron beam tomography coronary calcium imaging is an evolving technique for the early detection of coronary atherosclerosis, and recent studies have established its prognostic value in asymptomatic individuals. The relationship of coronary artery calcium scores (CAC) to obstructive coronary artery disease (CAD) has been poorly studied but is clinically relevant because it determines which individuals are likely to benefit from revascularization procedures. Hence, we prospectively evaluated the prevalence of myocardial ischemia in asymptomatic patients with cardiovascular risk factors and subclinical atherosclerosis. METHODS AND RESULTS: We studied 864 asymptomatic patients with no previous CAD but with cardiovascular risk factors, referred for electron beam tomography coronary calcium imaging to our institution over an 18-month period. From this group, 220 consecutive patients (85% men; mean age, 61 +/- 9 years; age range, 31-84 years) with moderate to severe atherosclerotic disease (coronary calcium score > or =100 Agatston units) were prospectively evaluated by technetium 99m sestamibi single photon emission computed tomography (SPECT). Patients were followed up (mean follow-up, 14 months) and data regarding their subsequent clinical management recorded. Of the 220 patients, 119 had moderate atherosclerosis (CAC score of 100-400 Agatston units) and 101 had severe atherosclerosis (CAC score > or =400 Agatston units). Abnormal SPECT findings were seen in 18% of patients with moderate atherosclerosis (n = 21) and 45% of patients with severe atherosclerosis (n = 45). Increasing severity of atherosclerosis was related to increasing ischemic burden (summed difference score = 1 +/- 0.2 for CAC score of 100-400 Agatston units and 3.2 +/- 0.5 for CAC score > or =400 Agatston units). In a multivariate linear regression model incorporating risk factors, CAC was the only predictor of silent ischemia. CONCLUSION: In comparison to previously published data, we detected a higher prevalence of silent ischemia even in patients with moderate coronary atherosclerosis (18%). This may reflect the differing risk factor profile of our patient population. When coronary calcium screening is used to preselect asymptomatic patients with cardiovascular risk factors for myocardial perfusion imaging, the optimum coronary calcium score threshold will depend on the population prevalence of risk factors and asymptomatic obstructive CAD. 相似文献