全文获取类型
收费全文 | 3278篇 |
免费 | 388篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 20篇 |
妇产科学 | 22篇 |
基础医学 | 500篇 |
口腔科学 | 43篇 |
临床医学 | 321篇 |
内科学 | 240篇 |
皮肤病学 | 18篇 |
神经病学 | 371篇 |
特种医学 | 492篇 |
外国民族医学 | 1篇 |
外科学 | 185篇 |
综合类 | 196篇 |
预防医学 | 779篇 |
眼科学 | 26篇 |
药学 | 369篇 |
中国医学 | 30篇 |
肿瘤学 | 74篇 |
出版年
2024年 | 9篇 |
2023年 | 69篇 |
2022年 | 104篇 |
2021年 | 128篇 |
2020年 | 139篇 |
2019年 | 119篇 |
2018年 | 115篇 |
2017年 | 160篇 |
2016年 | 141篇 |
2015年 | 132篇 |
2014年 | 198篇 |
2013年 | 242篇 |
2012年 | 154篇 |
2011年 | 145篇 |
2010年 | 125篇 |
2009年 | 165篇 |
2008年 | 158篇 |
2007年 | 172篇 |
2006年 | 134篇 |
2005年 | 123篇 |
2004年 | 99篇 |
2003年 | 114篇 |
2002年 | 84篇 |
2001年 | 66篇 |
2000年 | 48篇 |
1999年 | 50篇 |
1998年 | 52篇 |
1997年 | 46篇 |
1996年 | 41篇 |
1995年 | 39篇 |
1994年 | 39篇 |
1993年 | 35篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 18篇 |
1989年 | 30篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 13篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 5篇 |
排序方式: 共有3703条查询结果,搜索用时 0 毫秒
1.
2.
Sex estimation by various forensic anthropology approaches is a crucial factor for identification of human skeletal remains. However, inexpensive, uncomplicated and reliable methods are still required, especially in a remote crime scene and a high crime incidence area. Here, we examined 13 sacral parameters from 78 independent skeletons derived from deceases found in Central Thailand (male, n = 46; female, n = 32) using simple standard anthropometric techniques for sex allocation. Discriminant analysis exhibited that anterior-posterior diameter of S1 vertebra corpus (APS) is the most accurate sacral parameter for sex determination in our study with 82.1% of correct discrimination rate. The accuracy could be improved up to 97.4% when additional three sacral variables including the length of sacrum measured from the medial anterior-superior sacral promontory to the medial anterior-inferior S5 vertebra (ASL), alar index (ALI), and the maximum anterior breadth of sacrum measured across sacral alar (ABS) were computed together with APS. These encourage the use of sacral morphometrics for sex assessment of human sacrum remains in Central Thailand. However, further investigation with broadening sacral morphometric data across the country might provide a promising sex determination equation from a sacral skeleton for Thai population. 相似文献
3.
《Ultrasound in medicine & biology》2015,41(10):2562-2566
The primary aim of this study was to evaluate the accuracy of sonographic estimation of fetal weight when performed at due date by first-line sonographers. This was a prospective study including 500 singleton pregnancies. Ultrasound examinations were performed by residents on delivery day. Estimated fetal weights (EFWs) were calculated and compared with the corresponding birth weights. The median absolute difference between EFW and birth weight was 200 g (100–330). This difference was within ±10% in 75.2% of the cases. The median absolute percentage error was 5.53% (2.70%–10.03%). Linear regression analysis revealed a good correlation between EFW and birth weight (r = 0.79, p < 0.0001). According to Bland–Altman analysis, bias was −85.06 g (95% limits of agreement: −663.33 to 494.21). In conclusion, EFWs calculated by residents were as accurate as those calculated by experienced sonographers. Nevertheless, predictive performance remains limited, with a low sensitivity in the diagnosis of macrosomia. 相似文献
4.
Rik C. Schoemaker Joop M. A. van Gerven Adam F. Cohen 《Journal of pharmacokinetics and pharmacodynamics》1998,26(5):581-593
The most widely applied model relating drug concentrations to effects is the Emax
model. In practice, concentration–effect relationships often deviate from a simple linear relationship but without reaching a clear maximum because a further increase in concentration might be associated with unacceptable or distorting side effects. The parameters for the Emax
model can only be estimated with reasonable precision if the curve shows sign of reaching a maximum, otherwise both EC50
and Emax
estimates may be extremely imprecise. This paper provides a solution by introducing a new parameter (S0
) equal to Emax/EC50
that can be used to characterize potency adequately even if there are no signs of a clear maximum. Simulations are presented to investigate the nature of the new parameter and published examples are used as illustration. 相似文献
5.
C. Fischer W. Gross J. Krüger M. Cremer F. Vogel T. Grimm 《Annals of human genetics》2006,70(2):237-248
For several genetic diseases two biological phenomena have been recognised as important: germline mosaicism; and different new mutation rates in males and females depending on mutation type. Both principles have been investigated separately and their influence on risk estimation in families has been exemplified in the literature. The aim of this paper is to present a general model that includes mosaicism and different new mutation rates. Mosaicism is introduced by defining additional alleles at the disease locus in combination with adapted segregation rules. Taking Duchenne muscular dystrophy as an example, we derive the conditions which have to be fulfilled for a population in mutation selection equilibrium. Our approach describes the model at the population level and not in individual subjects. This has the advantage of being able to use well known algorithms for the calculation of likelihoods in pedigrees, and to include additional diagnostic information such as marker genotypes and carrier deletion test results. We demonstrate the impact of the new model on a typical pedigree. In families where the patient is not available, the distinction between point mutations and deletions is important, since often molecular diagnostic tests for females can only screen for deletions. Negative deletion test results can now be included in the risk calculations. 相似文献
6.
张作民 《中国脊柱脊髓杂志》1987,(2)
本文在介绍我院研制成的WKZX型微机自控系统的组成及性能基础上,提出了以微处理机为基础的数字自控系统设计及其规律。介绍了应用本装置所研究的几个实例——PWM微机伺服系统和发酵过程参数预值仿真及其控制等。 相似文献
7.
In the study of monozygotic twins relative to disease and risk factors, particular interest focuses on the subset who are discordant for some suspected risk factor (for example, smoking), since such twins constitute a natural case-control pair. In such studies, questionnaires designed to identify the status of all twin pairs are sometimes error prone and can yield misleading estimates of the concordance-discordance ratios. Greater efforts to verify the characteristics of apparently discordant pairs than to verify those of apparently concordant pairs can result in the 'unequal ascertainment' fallacy. Using the results of a questionnaire with known error rates and the 'apparent' frequencies yielded, we present unbiased, maximum likelihood estimates of the 'true' proportions of concordant and discordant pairs. concordant and discordant pairs. We also present approximate covariances among these estimates. 相似文献
8.
9.
赖玉熔 《福建医科大学学报》1992,(1)
对20~25岁的健康学生进行肺功能测定,肺活量(VC)、第一秒时间肺活量(FEV_1)、最大通气量(MBC)存在性别差异;而中期流速(MMEF_(25~75%))和第一秒时间肺活量占用力肺活量的百分比(FEV_1/FVC)无显著性差异。以身高(X_1),体重(X_2)为自变量,VC,FEV_1,MBC分别为应变量进行多元回归分析,显示肺功能指标和身高、体重有密切的相关性(P<0.05)。按体育锻炼指标将机体的素质分为较好、中等、较差3组,计算其肺功能实测值占预计值124.3±11.2%,105.8±13.3%,84.9±11.8%。 相似文献
10.
生理影像是功能性医学影像的一个重要分支,也是临床医学工程的一个极其重要的研究和应用领域。多年来,作者及其研究生与临床医务人员相结合,在电生理影像和热生理影像的信息获取和数字化处理技术方面进行了大量及深入的研究,提出了一种体内热估计(ITE)新技术。本文重点介绍热生理影像信息在妇女乳腺癌诊断中的应用。通过对约五千例妇女乳腺病筛选的结果,表明了生理影像信息处理及ITE技术在临床医学上的应用价值。 相似文献