全文获取类型
收费全文 | 134229篇 |
免费 | 11249篇 |
国内免费 | 7045篇 |
专业分类
耳鼻咽喉 | 1400篇 |
儿科学 | 2089篇 |
妇产科学 | 2792篇 |
基础医学 | 16892篇 |
口腔科学 | 2833篇 |
临床医学 | 16603篇 |
内科学 | 22034篇 |
皮肤病学 | 1459篇 |
神经病学 | 8267篇 |
特种医学 | 4639篇 |
外国民族医学 | 44篇 |
外科学 | 15212篇 |
综合类 | 16989篇 |
现状与发展 | 23篇 |
一般理论 | 28篇 |
预防医学 | 7942篇 |
眼科学 | 3513篇 |
药学 | 13458篇 |
56篇 | |
中国医学 | 5193篇 |
肿瘤学 | 11057篇 |
出版年
2024年 | 283篇 |
2023年 | 1596篇 |
2022年 | 4011篇 |
2021年 | 5356篇 |
2020年 | 3744篇 |
2019年 | 3582篇 |
2018年 | 4166篇 |
2017年 | 3420篇 |
2016年 | 3329篇 |
2015年 | 4970篇 |
2014年 | 6337篇 |
2013年 | 5952篇 |
2012年 | 8815篇 |
2011年 | 9553篇 |
2010年 | 5792篇 |
2009年 | 4516篇 |
2008年 | 6432篇 |
2007年 | 6792篇 |
2006年 | 6545篇 |
2005年 | 6663篇 |
2004年 | 4696篇 |
2003年 | 4199篇 |
2002年 | 3686篇 |
2001年 | 4620篇 |
2000年 | 4736篇 |
1999年 | 4431篇 |
1998年 | 2215篇 |
1997年 | 1911篇 |
1996年 | 1614篇 |
1995年 | 1427篇 |
1994年 | 1219篇 |
1993年 | 853篇 |
1992年 | 1957篇 |
1991年 | 1662篇 |
1990年 | 1446篇 |
1989年 | 1443篇 |
1988年 | 1350篇 |
1987年 | 1219篇 |
1986年 | 1066篇 |
1985年 | 904篇 |
1984年 | 577篇 |
1983年 | 470篇 |
1982年 | 253篇 |
1981年 | 225篇 |
1980年 | 196篇 |
1979年 | 312篇 |
1978年 | 137篇 |
1977年 | 137篇 |
1973年 | 130篇 |
1971年 | 132篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Xiaoguang Zhu Raymond Q Migrino Robert S Hellman Tejas Brahmbhatt Ming Zhao 《Nuclear medicine communications》2008,29(9):764-769
OBJECTIVE: The C2A domain of Synaptotagmin I is a molecular probe for the specific imaging of cell death. Here we test the hypothesis that the uptake of 99mTc-C2A in the acute phase of an infarction is associated with cardiac dysfunction in follow-ups. METHODS: The left coronary artery was occluded in Sprague-Dawley rats for 0, 10, 20, and 30 min. 99mTc-C2A was injected intravenously at 2 h of reperfusion. Anterior planar images were acquired with one million counts on a gamma camera 3 h after injection. 99mTc-C2A uptake was calculated as the total counts in the left ventricle region minus blood pool signal. The in-vivo signal detected was correlated with wall motion score index at 1 and 3 weeks follow-ups measured by echocardiography. RESULTS: 99mTc-C2A uptake was higher with increased ischemic time (2244+/-852, 4054+/-1223, and 6178+/-1451 for 10, 20, and 30 min ischemia, analysis of variance P<0.001). A significant correlation was found between 99mTc-C2A uptake and wall motion score index at 1 week (R=0.800, P=0.0006) and 3 weeks (R=0.810, P=0.0008). CONCLUSION: In this ischemia/reperfusion model, 99mTc-C2A uptake in the acute phase was associated with functional abnormality at 1 and 3 weeks. This demonstrates the potential diagnostic and prognostic value of 99mTc-C2A as a novel imaging agent. 相似文献
52.
J Chhabra Y-Z Li H Alkhouri A E Blake Q Ge C L Armour J M Hughes 《The European respiratory journal》2007,29(5):861-870
Degranulating mast cells are increased in the airway smooth muscle (ASM) of asthmatics, where they may influence ASM function. The aim of the present study was to determine whether histamine and tryptase modulate ASM cell granulocyte-macrophage colony-stimulating factor (GM-CSF) and RANTES (regulated on activation, normal T-cell expressed and secreted) release and also to examine which receptors are involved in this release. Confluent, quiescent ASM cells from asthmatic and nonasthmatic donors were treated with histamine (1 microM-100 microM) with and without histamine receptor antagonist pre-treatment, or the protease-activated receptor (PAR)-2 agonists tryptase (0.5-5 nM) and SLIGKV (100 and 400 microM). The cells were then stimulated with interleukin (IL)-1beta and/or tumour necrosis factor (TNF)-alpha (10 ng.mL(-1)) or left unstimulated for 24 h. Release of GM-CSF and RANTES was determined by ELISA and prostaglandin (PG)E(2) measured by enzyme immunoassay. Neither histamine nor tryptase induced ASM GM-CSF or RANTES secretion. However, histamine increased IL-1beta-induced GM-CSF release and markedly reduced TNF-alpha-induced RANTES release by both asthmatic and nonasthmatic cells to a similar extent, but did not modulate PGE(2) release. All changes involved activation of the histamine H1 receptor as they were partially or fully blocked by chlorpheniramine, but not ranitidine. Tryptase, via its proteolytic activity, also potentiated GM-CSF, but not RANTES, release from asthmatic and nonasthmatic ASM cells induced by both cytokines. PAR-2 involvement in the tryptase potentiation was unlikely because SLIGKV had no effect. In conclusion, mast cells, through histamine and tryptase, may locally modulate airway smooth muscle-induced inflammation in asthma. 相似文献
53.
风疹易感人群婚前风疹疫苗接种预防先天性风疹综合征 总被引:1,自引:0,他引:1
目的探讨婚前风疹易感人群风疹疫苗接种在提高孕妇对风疹的免疫力,预防先天性风疹综合征中的作用.方法对10 913例婚前风疹病毒抗体IgG阴性者给予国产风疹减毒活疫苗注射.3个月随防671例,比较风疹疫苗接种前后该地区孕妇近期风疹感染的发病率.结果818例风疹病毒抗体IgG阴性者接种后抗体转阳率为99.8%.风疹疫苗接种前后3年孕妇近期风疹感染率分别为0.37%及0.08%,有明显下降,有非常显著差异(P<0.001).结论应用国产风疹减毒活疫苗对婚前易感人群作预防接种可提高育龄妇女对风疹的免疫力,降低孕期风疹感染的发生率,是预防先天性风疹综合征及风疹致畸的有效、安全措施. 相似文献
54.
55.
56.
Mao-Sheng Ran Meng-Ze Xiang Jie Li Jian Huang Eric Yu-Hai Chen Cecilia Lai-Wan Chan Yeates Conwell 《Archives of Suicide Research》2007,11(1):119-127
The aim of this study was to compare the demographic and clinical characteristics of individuals with affective disorders who had attempted suicide at some time in their lives and those who had not made a suicide attempt. In a Chinese rural community, individuals with suicide attempt (N = 30) and those without suicide attempt (N = 166) were assessed with Present State Examination (PSE). Attempters had a significantly higher level of family economic status, higher rate of lifetime depressed mood and hopelessness, and delusions than nonattempters. The logistic regression models also indicated that depressed mood and hopelessness were the most important predictors of suicide attempts. No significant difference in treatment condition was found between attempters and non-attempters. Early identification and interventions focusing on reducing depressed mood, hopelessness, and controlling psychotic symptoms may be helpful in reducing the risk of suicide attempts among individuals with affective disorders residing in the community. 相似文献
57.
Teng-Yi Huang Hsiao-Wen Chung Fu-Nien Wang Cheng-Wen Ko Cheng-Yu Chen 《Magnetic resonance in medicine》2004,51(2):243-247
In this work the feasibility of separating fat and water signals using the balanced steady-state free precession (SSFP) technique is demonstrated. The technique is based on the observation (Scheffler and Hennig, Magnetic Resonance in Medicine 2003;49:395-397) that at the nominal values of TE = TR/2 in SSFP imaging, phase coherence can be achieved at essentially only two orientations (0 degrees and 180 degrees ) relative to the RF pulses in the rotating frame, under the assumption of TR < T2, and independently of the SSFP angle. This property allows in-phase and out-of-phase SSFP images to be obtained by proper choices of the center frequency offset, and thus allows the Dixon subtraction method to be utilized for effective fat-water separation. The TR and frequency offset for optimal fat-water separation are derived from theories. Experimental results from healthy subjects, using a 3.0 Tesla system, show that nearly complete fat suppression can be accomplished. 相似文献
58.
近年来,内窥镜下手术在眼科的应用有了很大进展,并且逐渐展现出其创伤小、并发症少、直视下操作、安全有效的优点。眼内窥镜联合激光可应用于青光眼前房角手术、青光眼睫状体光凝术、周边部视网膜玻璃体手术等等;另外泪道内窥镜在泪器疾病中的应用、鼻内窥镜在鼻眼相关手术中的应用也有很大的发展。眼内窥镜的应用开创了眼科微创手术时代。本文就眼用内窥镜的基本工作原理、应用现状和发展前景进行综述。 相似文献
59.
我科开展整体护理以来,将护理程序应用能力作为基础护理技能纳入临床护理教学计划中,提高了实习质量。现将具体做法介绍如下。 相似文献
60.
Epidemiologic studies have demonstrated that trans fat intake increases the risk of some chronic diseases. We hypothesize that trans fat intake would increase the risk of cardiovascular disease and type 2 diabetes mellitus by changing the lipid profile in plasma, the secretion of adipokines in adipose tissue, and the insulin sensitivity. Accordingly, the major objective of present study was to investigate the effect of dietary intake of trans fat on lipid profile, insulin sensitivity, and adipokine levels in plasma. Two groups of Wistar rats were fed a diet containing 4.5% trans fat or a control diet containing no trans fat for 16 weeks. Fasting glucose level was monitored every 2 weeks. At the end of feeding experiment, blood, heart, kidney, liver, omental adipose tissue, and semitendinosus muscle were collected. The trans fat content in organs, lipid profile, adipokine, insulin, and glucose levels in plasma were analyzed. The trans fat content in adipose tissue, heart, kidney, liver, and muscle of rats fed trans fat were 169.9, 0.6, 1.2, 1.7, and 2.5 mg/g samples, respectively. The trans fat content in these organs contributed to 15.9%, 1.2%, 2.3%, 4.3%, and 6.1% of the total fat, respectively. The plasma glucose level, insulin level, and insulin sensitivity index were not significantly different between the trans fat and control groups. The results indicated that trans fat intake might not be related to insulin resistance. However, lipid profile and plasma adipokine levels were significantly changed after trans fat feeding. The trans fat fed group showed significantly lower total cholesterol and high-density lipoprotein cholesterol levels than the control group. The decreased high-density lipoprotein cholesterol level may indicate the detrimental effect of trans fat intake on lipid profile. Adiponectin and resistin levels were significantly higher in the trans fat group than the control group. Leptin levels were significantly lower in the trans fat group than the control group. The results indicated that dietary intake of trans fat can significantly change the adipokine levels, but the possible links between adipokine level change caused by trans fat intake and metabolic effects of this change need further investigations. 相似文献