全文获取类型
收费全文 | 12910篇 |
免费 | 1486篇 |
国内免费 | 335篇 |
专业分类
耳鼻咽喉 | 58篇 |
儿科学 | 196篇 |
妇产科学 | 132篇 |
基础医学 | 1683篇 |
口腔科学 | 279篇 |
临床医学 | 1087篇 |
内科学 | 2225篇 |
皮肤病学 | 158篇 |
神经病学 | 777篇 |
特种医学 | 315篇 |
外国民族医学 | 2篇 |
外科学 | 577篇 |
综合类 | 1625篇 |
一般理论 | 3篇 |
预防医学 | 3266篇 |
眼科学 | 207篇 |
药学 | 1206篇 |
2篇 | |
中国医学 | 256篇 |
肿瘤学 | 677篇 |
出版年
2024年 | 33篇 |
2023年 | 253篇 |
2022年 | 404篇 |
2021年 | 559篇 |
2020年 | 531篇 |
2019年 | 522篇 |
2018年 | 467篇 |
2017年 | 548篇 |
2016年 | 520篇 |
2015年 | 594篇 |
2014年 | 893篇 |
2013年 | 1048篇 |
2012年 | 893篇 |
2011年 | 923篇 |
2010年 | 723篇 |
2009年 | 672篇 |
2008年 | 663篇 |
2007年 | 705篇 |
2006年 | 579篇 |
2005年 | 431篇 |
2004年 | 404篇 |
2003年 | 317篇 |
2002年 | 277篇 |
2001年 | 266篇 |
2000年 | 210篇 |
1999年 | 160篇 |
1998年 | 150篇 |
1997年 | 132篇 |
1996年 | 130篇 |
1995年 | 92篇 |
1994年 | 84篇 |
1993年 | 68篇 |
1992年 | 74篇 |
1991年 | 64篇 |
1990年 | 39篇 |
1989年 | 36篇 |
1988年 | 41篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 18篇 |
1983年 | 16篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 5篇 |
1974年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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
22.
E. Arroyo L. Prieto J. M. Ruiz de la Cuesta F. García-Sánchez J. L. Vicario 《International journal of legal medicine》1996,109(2):98-99
The fragment length polymorphism YNZ22 (D17S5) was analysed for a sample of 207 unrelated individuals living in Madrid (Spanish Caucasians) using PCR-methodology and high resolution separation. Hardy-Weinberg expectations (HWE) were calculated after pooling alleles into four groups. No deviations from HWE were detectable using the conventional 2-test. The power of discrimination was estimated as 0.96 and the mean paternity exclusion chance as 0.7587. A comparison of the allele frequency distribution with those of other Caucasian groups revealed no major differences. 相似文献
23.
R. Eckhorn A. Obermueller 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1993,95(1):177-182
Synchronised oscillatory population events (35–80 Hz; 60–300 ms) can be induced in the visual cortex of cats by specific visual stimulation. The oscillatory events are most prominent in local slow wave field potentials (LFP) and multiple unit spikes (MUA). We investigated how and when single cortical neurons are involved in such oscillatory population events. Simultaneous recordings of single cell spikes, LFP and MUA were made with up to seven microelectrodes. Three states of single cell participation in oscillations were distinguished in spike triggered averages of LFP or MUA from the same electrode: (1) Rhythmic states were characterised by the presence of rhythmicity in single cell spike patterns (35–80 Hz). These rhythms were correlated with LFP and MUA oscillations. (2) Lock-in states lacked rhythmic components in single cell spike patterns, while spikes were phase-coupled with LFP or MUA oscillations. (3) During non-participation states LFP or MUA oscillations were present, but single cell spike trains were neither rhythmic nor phase coupled to these oscillations. Stimulus manipulations (from optimal to suboptimal for the generation of oscillations) often led to systematic transitions between these states (from rhythmic to lock-in to non-participation). Single cell spike coupling was generally associated with negative peaks in LFP oscillations, irrespective of the cortical separation of single cell and population signals (0–6 mm). Our results suggest that oscillatory cortical population activities are not only supported by local and distant neurons with rhythmic spike patterns, but also by those with irregular patterns in which some spikes occur phase-locked to oscillatory events. 相似文献
24.
目的 用群体药代动力(PPK)模型和贝叶斯法预测血药浓度。方法 用癫痫儿童丙戊酸钠PPK模型和USC~*PACK软件中的贝叶斯程序,对100例新癫痫患儿丙戊酸钠的血药浓度进行预测。将预测值与实测值做配对t检验,相关和回归分析,计算平均预测误差、预测误差的百分比、不同预测误差百分比的符合率及其95%可信区间、构成比和评价预测的准确程度。结果 预测值与实测值的相关系数为0.99,P<0.001,线性回归Y_(OBS)=0.99)Y_(PRED),决定系数为0.98,P<0.001;平均预测误差为-0.43μg·mL~(-1),预测误差百分比分别为5%,10%,15%,20%,25%,30%的符合率为62%,74%,82%,85%,89%,93%。结论 PPK模型和贝叶斯法可准确预测丙戊酸钠稳态血药浓度。 相似文献
25.
The Human Genome Project will have an enormous impact on our ability to study and understand human disease by providing maps of human genes. However, many of the most prevalent human diseases result from the complex interaction of numerous genes. Even with the use of a catalogue of human genes, the task of analyzing complex genetic and environmental interactions involved in the common human disorders will be formidable. Due to its demographic specificities and large size, the Chinese population offers a unique resource for the study of human genetics and the ability to capitalize upon the recent revolution in biotechnology. Reasons that China provides an exceptional population for genetic studies of complex diseases include: (i) the resource of 1.3 billion people makes obtaining a large number of subjects with rare (and common) diseases possible; (ii) relative genetic homogeneity in many regions has been preserved; (iii) stratification is distinct; (iv) urban/rural and geograph ic contrasts, both in environmental factors and disease occurrence, are quite marked; (v) family members tend to stay congregated; and (vi) epidemiologic study is cost-beneficial. 相似文献
26.
乳腺癌干细胞相关亚群细胞周期分析 总被引:4,自引:0,他引:4
目的:流式细胞仪分选乳腺癌细胞系MCF-7的肿瘤干细胞相关SP亚群(side population,SP),并检测SP和非SP细胞周期。方法:MCF-7细胞悬液经Hoeehst33342染色,流式细胞仪分选SP和非SP后,乙醇固定,PI染色,流式细胞仪检测细胞周期。结果:SP细胞在MCF-7细胞中占4%,Vempamil阻断后比例减为0.5%。SP细胞中S/G2/M期细胞最低,仅占7.9%,而非SP细胞增殖期比例相对高,S/G2/M期细胞约占34.2%。未分选细胞中S/G2/M期细胞比例居中,为22.9%。结论:人乳腺癌细胞系MCF-7含SP亚群,比例约为4%,且SP细胞多处于静止期,具有一般干细胞的特性。 相似文献
27.
28.
Medial prefrontal cortex (mPfC) activity represents information about the state of the world, including present behavior, such as decisions, and the immediate past, such as short-term memory. Unknown is whether information about different states of the world are represented in the same mPfC neural population and, if so, how they are kept distinct. To address this, we analyze here mPfC population activity of male rats learning rules in a Y-maze, with self-initiated choice trials to an arm end followed by a self-paced return during the intertrial interval (ITI). We find that trial and ITI population activity from the same population fall into different low-dimensional subspaces. These subspaces encode different states of the world: multiple features of the task can be decoded from both trial and ITI activity, but the decoding axes for the same feature are roughly orthogonal between the two task phases, and the decodings are predominantly of features of the present during the trial but features of the preceding trial during the ITI. These subspace distinctions are carried forward into sleep, where population activity is preferentially reactivated in post-training sleep but differently for activity from the trial and ITI subspaces. Our results suggest that the problem of interference when representing different states of the world is solved in mPfC by population activity occupying different subspaces for the world states, which can be independently decoded by downstream targets and independently addressed by upstream inputs.SIGNIFICANCE STATEMENT Activity in the medial prefrontal cortex plays a role in representing the current and past states of the world. We show that during a maze task, the activity of a single population in medial prefrontal cortex represents at least two different states of the world. These representations were sequential and sufficiently distinct that a downstream population could separately read out either state from that activity. Moreover, the activity representing different states is differently reactivated in sleep. Different world states can thus be represented in the same medial prefrontal cortex population but in such a way that prevents potentially catastrophic interference between them. 相似文献
29.
Birth outcomes of patients with isolated anorectal malformations: A population‐based case‐control study 下载免费PDF全文
In most patients affected by isolated anorectal malformation (IARM) the etiology is largely unknown. Thus, the aim of our project was to analyze possible risk factors for IARM. In the first step, birth outcomes of cases with IARM were analyzed on the basis of maternal socio‐demographic variables, and these data are presented in this paper. Gestational age at delivery, birthweight, preterm birth, low birthweight and small for gestational age of cases with IARM were evaluated in the function of maternal age, birth/pregnancy order, marital and employment status of mothers in the population‐based large dataset of the Hungarian Case‐Control Surveillance of Congenital Abnormalities, 1980–1996. The study samples included 231 live‐born cases with IARM, 361 matched and 38 151 population controls without any defect. IARMs are more frequent in males, twins and newborn infants with low birthweight and small‐for‐gestational‐age, the latter being the consequence of intrauterine growth restriction. In addition, mothers of cases were younger but with higher birth order, and had lower socio‐economic status. These maternal variables are characteristic for the gypsy population in Hungary. The higher proportion of gypsy women among the mothers of cases with IARM was confirmed during the home visits of the study. Male sex and intrauterine growth restriction of cases, in addition to low socioeconomic status and gypsy origin of mothers may have a role in the risk of IARMs. 相似文献
30.