全文获取类型
收费全文 | 1610261篇 |
免费 | 117910篇 |
国内免费 | 3113篇 |
专业分类
耳鼻咽喉 | 23229篇 |
儿科学 | 49992篇 |
妇产科学 | 43300篇 |
基础医学 | 240643篇 |
口腔科学 | 47511篇 |
临床医学 | 142687篇 |
内科学 | 303237篇 |
皮肤病学 | 34958篇 |
神经病学 | 125590篇 |
特种医学 | 62935篇 |
外国民族医学 | 242篇 |
外科学 | 246247篇 |
综合类 | 38188篇 |
现状与发展 | 3篇 |
一般理论 | 444篇 |
预防医学 | 120013篇 |
眼科学 | 38064篇 |
药学 | 121593篇 |
3篇 | |
中国医学 | 3968篇 |
肿瘤学 | 88437篇 |
出版年
2018年 | 16925篇 |
2017年 | 13423篇 |
2016年 | 15463篇 |
2015年 | 16829篇 |
2014年 | 22848篇 |
2013年 | 35381篇 |
2012年 | 46961篇 |
2011年 | 49948篇 |
2010年 | 29217篇 |
2009年 | 26348篇 |
2008年 | 47399篇 |
2007年 | 51310篇 |
2006年 | 51123篇 |
2005年 | 49434篇 |
2004年 | 48177篇 |
2003年 | 46480篇 |
2002年 | 45034篇 |
2001年 | 71516篇 |
2000年 | 73918篇 |
1999年 | 60531篇 |
1998年 | 17452篇 |
1997年 | 15429篇 |
1996年 | 15348篇 |
1995年 | 14468篇 |
1994年 | 13675篇 |
1992年 | 47678篇 |
1991年 | 46928篇 |
1990年 | 46006篇 |
1989年 | 44951篇 |
1988年 | 41549篇 |
1987年 | 40613篇 |
1986年 | 38579篇 |
1985年 | 37179篇 |
1984年 | 28308篇 |
1983年 | 24106篇 |
1982年 | 14611篇 |
1981年 | 13284篇 |
1979年 | 27380篇 |
1978年 | 19732篇 |
1977年 | 16757篇 |
1976年 | 15664篇 |
1975年 | 17072篇 |
1974年 | 20652篇 |
1973年 | 19715篇 |
1972年 | 18644篇 |
1971年 | 17367篇 |
1970年 | 16610篇 |
1969年 | 15814篇 |
1968年 | 14401篇 |
1967年 | 13161篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
C T Gan G P McCann J T Marcus S A van Wolferen J W Twisk A Boonstra P E Postmus A Vonk-Noordegraaf 《The European respiratory journal》2006,28(6):1190-1194
The aim of the current study was to investigate whether alterations in N-terminal pro brain natriuretic peptide (NT-proBNP) reflect changes in right ventricular structure and function in pulmonary hypertension patients during treatment. The study consisted of 30 pulmonary hypertension patients; 15 newly diagnosed and 15 on long-term treatment. NT-proBNP, right heart catheterisation and cardiac magnetic resonance imaging measurements were performed, at baseline and follow-up. There were no significant differences between newly diagnosed patients and those on treatment at baseline or follow-up with respect to NT-proBNP, haemodynamics and right ventricular parameters. Relative changes in NT-proBNP during treatment were correlated to the relative changes in right ventricular end-diastolic volume index (r = 0.59), right ventricular mass index (r = 0.62) and right ventricular ejection fraction (r = -0.81). N-terminal pro brain natriuretic peptide measurements reflect changes in magnetic resonance imaging-measured right ventricular structure and function in pulmonary hypertension patients. An increase in N-terminal pro brain natriuretic peptide over time reflects right ventricular dilatation concomitant to hypertrophy and deterioration of systolic function. 相似文献
72.
73.
74.
Chan C. H. Y Ng E. H. Y Chan C. L W 《世界核心医学期刊文摘》2006,2(6):15-15
目的:评价东部身体-智力-精神(EBMS)群体干预对进行体外受精(IVF)的中国妇女焦虑缓解的作用。设计:随机对照研究。机构:三级辅助生殖机构。受试者:227例接受第1个IVF周期治疗的妇女。干预:干预组(n=69)接受4次EBMS群体咨询,而对照组(n=115)无任何干预。主要观察指标:状态-特质焦虑问卷。结果:与对照组相比,干预组在干预后状态焦虑平均分显著下降。每组移植同样数目的卵子,但干预组没有明显更高妊娠率的倾向。 相似文献
75.
76.
77.
Antony E. Shrimpton Robert L. Schelper Reinhold P. Linke John Hardy Richard Crook Dennis W. Dickson Takashi Ishizawa Richard L. Davis 《Neuropathology》2007,27(3):228-232
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family. 相似文献
78.
S Aquilina† M Dalmas‡ N Calleja§ P Gatt† L Scerri† 《Journal of the European Academy of Dermatology and Venereology》2006,20(8):958-963
BACKGROUND: The incidence of malignant melanoma of the skin has risen in every part of the world where reliable cancer registration data are found. OBJECTIVE: Our study aims to describe the changing incidence of and survival from invasive cutaneous malignant melanoma in Malta, by analysing the data from the 211 cases that were registered at the Malta National Cancer Registry between 1993 and 2002. RESULTS: The age standardized incidence rates for invasive cutaneous malignant melanoma rose from 3.7 per 100,000 population per year for males and 5.1 for females in the first 5-year period, to 8.0 per 100,000 population per year for males and 5.9 for females in the second 5-year period. In both sexes, numbers of thin (< or = 1.0 mm) invasive melanomas increased significantly between 1993 and 2002; males also registered a significant increase in intermediate-thickness (1.01-4.0 mm) melanomas. The increase in numbers of thin and intermediate-thickness melanomas between the two 5-year periods was greatest in patients aged 60 years and over. The overall absolute 5-year survival rate for the first period was 74% and for the second period 92%. CONCLUSION: Numbers of reported cases of invasive cutaneous malignant melanoma in Malta have more than doubled during the 10-year study period. This is mostly due to a marked rise in the diagnosis of thin melanomas in both sexes, occurring mainly in patients aged 60 years and over. As thin melanomas are of low metastasizing potential, this has resulted in an increase in survival between the two 5-year study periods. 相似文献
79.
80.
Sami S Zoghbi H Umesha Shetty Masanori Ichise Masahiro Fujita Masao Imaizumi Jeih-San Liow Jay Shah John L Musachio Victor W Pike Robert B Innis 《Journal of nuclear medicine》2006,47(3):520-527
18F-2beta-Carbomethoxy-3beta-(4-chlorophenyl)-8-(2-fluoroethyl)nortropane (18F-FECNT), a PET radioligand for the dopamine transporter (DAT), generates a radiometabolite that enters the rat brain. The aims of this study were to characterize this radiometabolite and to determine whether a similar phenomenon occurs in human and nonhuman primate brains by examining the stability of the apparent distribution volume in DAT-rich (striatum) and DAT-poor (cerebellum) regions of the brain. METHODS: Two rats were infused with 18F-FECNT and sacrificed at 60 min. Extracts of brain and plasma were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometric (LC-MS) techniques. Two human participants and 3 rhesus monkeys were injected with 18F-FECNT and scanned kinetically, with serial arterial blood analysis. RESULTS: At 60 min after the injection of rats, 18F-FECNT accumulated to levels about 7 times higher in the striatum than in the cortex and cerebellum. The radiometabolite was distributed at equal concentrations in all brain regions. The LC-MS techniques identified N-dealkylated FECNT as a major metabolite in the rat brain, and reverse-phase HPLC detected an equivalent amount of radiometabolite eluting with the void volume. The radiometabolite likely was 18F-fluoroacetaldehyde, the product expected from the N-dealkylation of 18F-FECNT, or its oxidation product, 18F-fluoroacetic acid. The distribution volume in the cerebellum increased up to 1.7-fold in humans between 60 and 300 min after injection and 2.0 +/- 0.1-fold (mean +/- SD; n = 3) in nonhuman primates between 60 and 240 min after injection. CONCLUSION: An 18F-fluoroalkyl metabolite of 18F-FECNT originating in the periphery confounded the measurements of DAT in the rat brain with a reference tissue model. Its uniform distribution across brain regions suggests that it has negligible affinity for DAT (i.e., it is an inactive radiometabolite). Consistent with the rodent data, the apparent distribution volume in the cerebellum of both humans and nonhuman primates showed a continual increase at late times after injection, a result that may be attributed to entry of the radiometabolite into the brain. Thus, reference tissue modeling of 18F-FECNT will be prone to more errors than analysis with a measured arterial input function. 相似文献