全文获取类型
收费全文 | 1726篇 |
免费 | 142篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 106篇 |
儿科学 | 26篇 |
妇产科学 | 15篇 |
基础医学 | 374篇 |
口腔科学 | 22篇 |
临床医学 | 140篇 |
内科学 | 186篇 |
皮肤病学 | 8篇 |
神经病学 | 169篇 |
特种医学 | 64篇 |
外科学 | 90篇 |
综合类 | 124篇 |
预防医学 | 259篇 |
眼科学 | 41篇 |
药学 | 138篇 |
中国医学 | 88篇 |
肿瘤学 | 55篇 |
出版年
2024年 | 6篇 |
2023年 | 26篇 |
2022年 | 49篇 |
2021年 | 65篇 |
2020年 | 62篇 |
2019年 | 81篇 |
2018年 | 56篇 |
2017年 | 44篇 |
2016年 | 36篇 |
2015年 | 47篇 |
2014年 | 97篇 |
2013年 | 139篇 |
2012年 | 78篇 |
2011年 | 89篇 |
2010年 | 61篇 |
2009年 | 82篇 |
2008年 | 86篇 |
2007年 | 61篇 |
2006年 | 65篇 |
2005年 | 50篇 |
2004年 | 53篇 |
2003年 | 54篇 |
2002年 | 33篇 |
2001年 | 32篇 |
2000年 | 29篇 |
1999年 | 40篇 |
1998年 | 25篇 |
1997年 | 25篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 18篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 18篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1971年 | 6篇 |
排序方式: 共有1905条查询结果,搜索用时 15 毫秒
1.
CYP2E1 and ALDH2 Genotypes and Alcohol Dependence in Japanese 总被引:2,自引:0,他引:2
Kazuhiko Iwahashi Yoshinori Matsuo Hiroshi Suwaki Kazuhiko Nakamura Yoshiyuki Ichikawa 《Alcoholism, clinical and experimental research》1995,19(3):564-566
The genotypes of the CYP2E1 and ALDH2 loci of alcoholic (alcohol dependence) and nonalcoholic (healthy) Japanese were investigated to examine the relationship between the polymorphism of CYP2E1 (C1 /C2 ) and ALDH2 ( ALDH2*1/ALDH2*2 ), and the susceptibility to alcoholism. There was no significant difference in C2 gene frequency between alcoholics (0.19) and nonalcoholics (controls) (0.20), whereas there was a significant difference in ALDH2 allele frequency, suggesting that, in Japanese, the C2 genotype of CYP2E1 may have nothing to do with the risk of developing alcohol dependence. However, the ALDH2*1 allele may influence drinking behavior and the development of alcohol dependence. Furthermore, racial interethnic differences in the frequency of the mutated allele of the CYP2E1 gene (CJ were found, like the ALDH2 gene. Japanese healthy controls showed a significantly higher frequency of the C2 allele than did Swedish healthy controls (0.05; reported by Persson et al., FEBS Lett. 319:207-211,1993). 相似文献
2.
阳江高本底地区居民健康流行病学调查数据库与统计分析方法 总被引:1,自引:0,他引:1
目的 研究应用计算机数据库技术及先进统计分析方法,对阳江高本底地区10多万人20余年的健康随访研究资料和剂量学调查资料进行储存、管理和分析。方法 通过调研和比较分析,确定采用Foxbase系列数据库管理系统按专题建立数据库,借助于ID号实现记录连接;一般统计分析由SAS完成;交叉分组人年列表由Epicure中的Datab完成;癌症相对危险分析用AMFIT程序。结果 建立了40MB的各专题研究库,主要包括:10余万人的人口学数据库(1979~1995)、1.2万人的死因数据库(1979~1995)和526个村庄6783户、5273人的剂量数据库。提出了动态群组研究资料(1979~1986)与固定群组研究资料(1987~1995)的合并方法:首选方法是建立假想的基于记录连接的以1979年为起点的(固定)群组。另一方法是将不同阶段群组研究的人年表分层直接相加。计算了每个成员基于卧室内、起居室内、室外村平均剂量率与性别-年龄别居留因子的累积剂量。完成了以性别、atainedage、随访年代及剂量交叉分组的人年列表,对癌症死亡资料(1979~1990)进行了危险分析。结论 应用计算机数据库管理系统与统计分析技术使阳江高本底地区研 相似文献
3.
4.
The risk estimates for individual carriers of ten different familial reciprocal translocations detected among 500 couples with reproductive failures are presented. These were established by application of the empirical data analysed by Stengel-Rutkowski et al. (1988) and the guidelines given in Stene & Stengel-Rutkowski (1988). Different risks were estimated for unbalanced offspring at birth or at second trimester prenatal diagnosis for abortions, or stillbirths/early deaths. These risk estimates varied considerably from translocation to translocation. Carriers of five translocations had risks for offspring with single-segment imbalances. The birth risk figures ranged from 0.1% to 13.8%. Carriers of five other translocations had risks for double-segment imbalances with birth risks ranging from 0% to 3.2%. The estimated risk figures were independent of the method of ascertainment. Among the parents of the index cases we found nine maternal carriers and only one paternal carrier. This presentation illustrates the need for individual risk counselling of each carrier with reciprocal translocation regarding further family planning. 相似文献
5.
目的探讨50岁以上正常人左室舒张期脉冲多普勒频谱的参数变化情况。方法选择一年半时间内受检的所有50岁以上正常人475例,按每10岁为一组分4组进行分析。受检者取左侧卧位,常规显示心尖四腔心切面,取样容积置于二尖瓣尖,使声束与二尖瓣血流方向夹角<15°,以连续三个心动周期的平均值分别测量E峰、A峰、E/A及E峰减速时间并统计。结果发现E峰高于正常值低限的例数、平均E峰血流速度以及E/A均随着年龄的增加而下降,E峰减速时间则随着增龄而增加。结论左室舒张期血流频谱的所有参数与年龄有显著的相关性,明显随着增龄而变化,并且有其规律性。 相似文献
6.
Tetsuya Sato Kaoru Sakado Sotoshi Sato 《European archives of psychiatry and clinical neuroscience》1993,242(5):273-278
Summary We investigated the frequency of personality disorders (PDs) and the relationship between the pressence of PD and the 4-month outcome of depression under adequate antidepressant therapy in a Japanese sample of 96 outpatients with non-bipolar major depression. The diagnosis of PD was made using a structured interiew method (the Structured Clinical Interview for DSM-III-R Personality Disorders) and after severe depressive symptoms were reduced. Any one kind of PD was found in 54.2% of the saple. The most frequent was avidant (34–4%), obsessived-compulsive (22.9%), narcisstic (18.8%), and dependent (16.7%) PDs. The frequencies of these PDs in our study except narcisstic PD, were about the same as those reported in previous studies with a matched setting for the PD diagnosis. Compared with patients without PD, a worse outcome was found in patients with PD, especially patients with multiple PDs from multiple PD clussters. There was no evidence that a specific PD or PD cluster especially worsens the outcome of depression. 相似文献
7.
8.
Roberto Merletti Mohamed A. Sabbahi Carlo J. De Luca 《European journal of applied physiology》1984,52(3):258-265
Summary A study was performed to investigate the changes that occur in the median frequency of the myoelectric signal during local ischemia or reduction of intramuscular temperature produced by surface cooling. Data was obtained from experiments which involved the first dorsal interosseous muscle of 10 female and 16 male subjects. These subjects were asked to perform isometric constant-force abduction contractions of the index finger at 20% and 80% of maximal voluntary contraction level. The initial median frequency (IMF) of the myoelectric signal during the first 0.5 s of contraction was calculated. Results showed a significant reduction of the IMF in contractions performed under ischemic conditions; upon release, the IMF recovered quickly. At 80% maximal voluntary level of contraction, a greater decrease of the IMF was recorded. Similar results were demonstrated during reduction of intramuscular temperature with gradual recovery of the IMF after cooling. These results demonstrate that the median frequency of the myoelectric signal displays behavior similar to that reported for conduction velocity and this is consistent with the notion that accumulation of metabolic byproducts in muscle tissue causes a decrease in the conduction velocity of the muscle fibers.Dr. R. Merletti was on a leave of absence from the Institute of Electrical Engineering, Politecnico di Torino, Italy 相似文献
9.
Lazar A Gründemann D Berkels R Taubert D Zimmermann T Schömig E 《Journal of human genetics》2003,48(5):226-230
The extraneuronal monoamine transporter EMT (HGNC Nomenclature SLC22A3) is the molecular correlate of the classical uptake2 system responsible for the non-neuronal inactivation of circulating and centrally released catecholamines. Because of its
functional profile and expression pattern, EMT is regarded as a candidate gene for diseases related to the sympathetic nervous
system and neuropsychiatric disorders. We describe the first investigation of the genetic variability of the EMT gene in human.
Six single-nucleotide substitutions and one deletion were detected within the assumed core promoter, the exonic and flanking
intronic sequences and the 3'-untranslated region in 100 Caucasian individuals. No amino acid changes were found and Tajima's
D was positive (D=2.91; P<0.01). However, the synonymous nucleotide substitution 1233G→A might serve as a cryptic splice acceptor site. Analysis of
linkage disequilibrium between polymorphisms yielded 12 possible haplotypes accounting for more than 90% of all haplotypes.
Knowledge of the sequence variation and frequency of the underlying polymorphisms in this member of the amphiphilic solute
facilitator family of transporters provides the basis for subsequent association studies and candidate gene approaches.
Electronic Publication 相似文献
10.
Grimstone SK Hodges PW 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2003,151(2):218-224
This study evaluated the degree to which the disturbance to posture from respiration is compensated for in healthy normals
and whether this is different in people with recurrent low back pain (LBP), and to compare the changes when respiratory demand
is increased. Angular displacement of the lumbar spine and hips, and motion of the centre of pressure (COP), were recorded
with high resolution and respiratory phase was recorded from ribcage motion. With subjects standing in a relaxed posture,
recordings were made during quiet breathing, while breathing with increased dead-space to induce hypercapnoea, and while subjects
voluntarily increased their respiration to match ribcage expansion that was induced in the hypercapnoea condition. The relationship
between respiration and the movement parameters was measured from the coherence between breathing and COP and angular motion
at the frequency of respiration, and from averages triggered from the respiratory data. Small angular changes in the lumbopelvic
and hip angles were evident at the frequency of respiration in both groups. However, in quiet standing, the LBP subjects had
a greater displacement of their COP that was associated with respiration than the control subjects. The LBP group had a trend
for less hip motion. There were no changes in the movement parameters when respiratory demand increased involuntarily via
hypercapnoea, but when respiration increased voluntarily, the amplitude of motion and the displacement of the COP increased
in both groups. The present data suggest that the postural compensation to respiration counteracts at least part of the disturbance
to posture caused by respiration and that this compensation may be less effective in people with LBP. 相似文献