全文获取类型
收费全文 | 1074918篇 |
免费 | 71566篇 |
国内免费 | 1361篇 |
专业分类
耳鼻咽喉 | 15015篇 |
儿科学 | 34609篇 |
妇产科学 | 28623篇 |
基础医学 | 153387篇 |
口腔科学 | 29553篇 |
临床医学 | 94904篇 |
内科学 | 203622篇 |
皮肤病学 | 24391篇 |
神经病学 | 81436篇 |
特种医学 | 42961篇 |
外国民族医学 | 201篇 |
外科学 | 163088篇 |
综合类 | 21702篇 |
现状与发展 | 1篇 |
一般理论 | 263篇 |
预防医学 | 74600篇 |
眼科学 | 24535篇 |
药学 | 86101篇 |
7篇 | |
中国医学 | 2805篇 |
肿瘤学 | 66041篇 |
出版年
2019年 | 7755篇 |
2018年 | 11293篇 |
2017年 | 8906篇 |
2016年 | 10094篇 |
2015年 | 11260篇 |
2014年 | 15267篇 |
2013年 | 22197篇 |
2012年 | 30543篇 |
2011年 | 32284篇 |
2010年 | 18949篇 |
2009年 | 17814篇 |
2008年 | 29946篇 |
2007年 | 32064篇 |
2006年 | 32699篇 |
2005年 | 31027篇 |
2004年 | 29720篇 |
2003年 | 28548篇 |
2002年 | 27524篇 |
2001年 | 60019篇 |
2000年 | 61475篇 |
1999年 | 50927篇 |
1998年 | 12443篇 |
1997年 | 10999篇 |
1996年 | 11014篇 |
1995年 | 10320篇 |
1994年 | 9341篇 |
1993年 | 8857篇 |
1992年 | 37788篇 |
1991年 | 36273篇 |
1990年 | 35744篇 |
1989年 | 34285篇 |
1988年 | 30864篇 |
1987年 | 29986篇 |
1986年 | 28214篇 |
1985年 | 26448篇 |
1984年 | 19185篇 |
1983年 | 16113篇 |
1982年 | 8822篇 |
1979年 | 17029篇 |
1978年 | 11404篇 |
1977年 | 10229篇 |
1976年 | 8837篇 |
1975年 | 10068篇 |
1974年 | 11651篇 |
1973年 | 11273篇 |
1972年 | 10754篇 |
1971年 | 10092篇 |
1970年 | 9252篇 |
1969年 | 8938篇 |
1968年 | 7917篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Suchi Raghunathan Corey L. Reynolds Robert J. Schwartz M. David Stewart Bradley K. McConnell 《Fundamental & clinical pharmacology》2019,33(1):25-30
Inbred mouse strains are the most widely used mammalian model organism in biomedical research owing to ease of genetic manipulation and short lifespan; however, each inbred strain possesses a unique repertoire of deleterious homozygous alleles that can make a specific strain more susceptible to a particular disease. In the current study, we report dystrophic cardiac calcinosis (DCC) in C.B‐17 SCID male mice at 10 weeks of age with no significant change in cardiac function. Acquisition of DCC was characterized by myocardial injury, fibrosis, calcification, and necrosis of the tissue. At 10 weeks of age, 38% of the C.B‐17 SCID mice from two different commercial colonies exhibited significant calcinosis on the ventricular epicardium, predominantly on the right ventricle. The frequency of calcinosis was more than 50% for mice obtained from Taconic's Cambridge City colony and 25% for mice obtained from Taconic's German Town colony. Interestingly, the DCC phenotype did not affect cardiac function at 10 weeks of age. No differences in echocardiography or electrocardiography were observed between the calcinotic and non‐calcinotic mice from either colony. Our findings suggest that C.B‐17 SCID mice exhibit DCC as early as 10 weeks of age with no significant impact on cardiac function. This strain of mice should be cautiously considered for the study of cardiac physiology. 相似文献
82.
83.
84.
85.
86.
Konrad Matyja Anna Małachowska-Jutsz Anna K. Mazur Kazimierz Grabas 《Ecotoxicology (London, England)》2016,25(5):924-939
Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (TMDTE). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and TMDTE are more appropriate than EC50 and IC50 for toxicity assessments, except for long exposure times. 相似文献
87.
As countries implement Article 11 of the World Health Organization (WHO) Framework Convention on Tobacco Control, graphic warning labels that use images of people and their body parts to illustrate the consequences of smoking are being added to cigarette packs. According to exemplification theory, these case examples—exemplars—can shape perceptions about risk and may resonate differently among demographic subpopulations. Drawing on data from eight focus groups (N = 63) with smokers and nonsmokers from vulnerable populations, this qualitative study explores whether people considered exemplars in their reactions to and evaluations of U.S. graphic health warning labels initially proposed by the Food and Drug Administration. Participants made reference to prior and concurrent mass media messages and exemplars during the focus groups and used demographic cues in making sense of the images on the warning labels. Participants were particularly sensitive to age of the exemplars and how it might affect label effectiveness and beliefs about smoking. Race and socioeconomic status also were salient for some participants. We recommend that exemplars and exemplification be considered when selecting and evaluating graphic health warnings for tobacco labels and associated media campaigns. 相似文献
88.
D. Panigrahy P. K. Sahu 《Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine》2016,39(3):783-795
Electrocardiogram (ECG) signal gives a lot of information on the physiology of heart. In reality, noise from various sources interfere with the ECG signal. To get the correct information on physiology of the heart, noise cancellation of the ECG signal is required. In this paper, the effectiveness of extended Kalman smoother (EKS) with the differential evolution (DE) technique for noise cancellation of the ECG signal is investigated. DE is used as an automatic parameter selection method for the selection of ten optimized components of the ECG signal, and those are used to create the ECG signal according to the real ECG signal. These parameters are used by the EKS for the development of the state equation and also for initialization of the parameters of EKS. EKS framework is used for denoising the ECG signal from the single channel. The effectiveness of proposed noise cancellation technique has been evaluated by adding white, colored Gaussian noise and real muscle artifact noise at different SNR to some visually clean ECG signals from the MIT-BIH arrhythmia database. The proposed noise cancellation technique of ECG signal shows better signal to noise ratio (SNR) improvement, lesser mean square error (MSE) and percent of distortion (PRD) compared to other well-known methods. 相似文献
89.
90.