全文获取类型
收费全文 | 7745篇 |
免费 | 651篇 |
国内免费 | 203篇 |
专业分类
耳鼻咽喉 | 51篇 |
儿科学 | 85篇 |
妇产科学 | 70篇 |
基础医学 | 1164篇 |
口腔科学 | 186篇 |
临床医学 | 560篇 |
内科学 | 1029篇 |
皮肤病学 | 155篇 |
神经病学 | 631篇 |
特种医学 | 249篇 |
外科学 | 649篇 |
综合类 | 771篇 |
现状与发展 | 1篇 |
预防医学 | 963篇 |
眼科学 | 128篇 |
药学 | 1053篇 |
3篇 | |
中国医学 | 358篇 |
肿瘤学 | 493篇 |
出版年
2024年 | 22篇 |
2023年 | 135篇 |
2022年 | 246篇 |
2021年 | 308篇 |
2020年 | 287篇 |
2019年 | 269篇 |
2018年 | 252篇 |
2017年 | 256篇 |
2016年 | 279篇 |
2015年 | 256篇 |
2014年 | 484篇 |
2013年 | 632篇 |
2012年 | 410篇 |
2011年 | 458篇 |
2010年 | 351篇 |
2009年 | 334篇 |
2008年 | 375篇 |
2007年 | 355篇 |
2006年 | 307篇 |
2005年 | 272篇 |
2004年 | 209篇 |
2003年 | 171篇 |
2002年 | 148篇 |
2001年 | 131篇 |
2000年 | 135篇 |
1999年 | 108篇 |
1998年 | 106篇 |
1997年 | 86篇 |
1996年 | 83篇 |
1995年 | 75篇 |
1994年 | 78篇 |
1993年 | 79篇 |
1992年 | 71篇 |
1991年 | 69篇 |
1990年 | 61篇 |
1989年 | 37篇 |
1988年 | 44篇 |
1987年 | 46篇 |
1986年 | 35篇 |
1985年 | 71篇 |
1984年 | 51篇 |
1983年 | 51篇 |
1982年 | 55篇 |
1981年 | 47篇 |
1980年 | 34篇 |
1979年 | 51篇 |
1978年 | 37篇 |
1977年 | 31篇 |
1976年 | 33篇 |
1975年 | 27篇 |
排序方式: 共有8599条查询结果,搜索用时 31 毫秒
1.
内生菌由细菌、真菌、古菌和原生生物组成,它们生活在植物的活体组织中,具有丰富的次级代谢产物多样性。人参内生菌在人参的生长发育、次级代谢产物的生成和环境适应等方面均有重要的促进作用,对人参的产量和品质有较大影响。随着人们在微生物领域研究的深入,高通量测序技术已经成为研究植物内生菌的重要方法。文章主要从人参内生菌分离与鉴定研究方法、人参内生菌的多样性、人参内生菌及其次级代谢产物的活性、人参内生菌对宿主的影响等4个方面对人参内生菌近年来的研究进展进行讨论,并对其发展方向提出展望,以期为药用植物内生菌研究和品质改良提供新思路、新方法。 相似文献
2.
3.
当代社会,老年人口比例呈现不断上升的趋势,老龄化问题日益严峻。因此,如何有效地延缓衰老不仅成为了世界医学研究的热点,也成为了全球亟待解决的问题。中医药在延缓衰老方面经验丰富,而滋阴药在此类研究中效果显著。本文通过整理滋阴药抗衰老作用机制的若干文献,对滋阴复方六味地黄丸、二至丸、左归丸及其他滋阴中药延缓衰老的机制研究进展进行综述。 相似文献
4.
Unconditional Positivity-Preserving and Energy Stable Schemes for a Reduced Poisson-Nernst-Planck System 下载免费PDF全文
Hailiang Liu & Wumaier Maimaitiyiming 《Communications In Computational Physics》2020,27(5):1505-1529
The Poisson-Nernst-Planck (PNP) system is a widely accepted model for
simulation of ionic channels. In this paper, we design, analyze, and numerically validate a second order unconditional positivity-preserving scheme for solving a reduced
PNP system, which can well approximate the three dimensional ion channel problem.
Positivity of numerical solutions is proven to hold true independent of the size of time
steps and the choice of the Poisson solver. The scheme is easy to implement without
resorting to any iteration method. Several numerical examples further confirm the
positivity-preserving property, and demonstrate the accuracy, efficiency, and robustness of the proposed scheme, as well as the fast approach to steady states. 相似文献
5.
《Biomedical and environmental sciences : BES》2020,33(2):89-102
Objective The present study aims to investigate the concentrations of Hg and its aspects methyl mercury(Me-Hg) and inorganic mercury(I-Hg) in the biological samples(BSs) of fluorescent lamp industries workers(FLIWs).Methodology Different BSs including red blood cells(RBCs),plasma,urine,hair and nails were collected from the workers exposed to Hg and unexposed persons were selected as control group to measure both the T-Hg concentration as well as its species in different biological samples through quantitative analysis.Health data was collected through questionnaire survey.Results The mean concentrations of T-Hg(31.9 μg/L),Me-Hg(27.7 μg/L),and I-Hg(5.36 μg/L) in RBCs were found significantly(P 0.001) higher among the workers(n = 40) as compared to the control group(n = 40).Similarly the mean Hg concentrations in plasma,urine,hair and nails were also significantly higher among the workers than the control group.The statistical relation between Hg concentration and demographic characteristics observed that workers experience and fish consumption has increased the Hg concentration while age,weight and smoking found no significant effect on Hg concentration in the BSs.Conclusion The study observed that the workers were highly exposed to high concentration of Hg and they are at a high health risk. 相似文献
6.
Francisca Morgado Mariana Batista Ana Moreno Inês Coutinho 《Pediatric dermatology》2021,38(1):191-193
We present a 6‐year‐old girl with skin hyperpigmentation, leukoplakia, and onychodystrophy, the classic mucocutaneous triad usually associated with dyskeratosis congenita. The patient also had premature graying of the hair, bone marrow failure, hepatitis, exudative retinopathy, osteopenia with multiple long bone fractures, and intracranial calcifications and brain cysts. Coats plus syndrome is a rare disease with a clinical and genetic overlap with dyskeratosis congenita. This disease is reviewed, with a focus on the pathogenesis of the genetic anomalies and its background as a telomere biology disorder. 相似文献
7.
The Local Lymph Node Assay (LLNA) is the most common in vivo regulatory toxicology test for skin sensitisation, quantifying potency as the EC3, the concentration of chemical giving a threefold increase in thymidine uptake in the local lymph node. Existing LLNA data can, along with clinical data, provide useful comparator information on the potency of sensitisers. Understanding of the biological variability of data from LLNA studies is important for those developing non-animal based risk assessment approaches for skin allergy. Here an existing set of 94 EC3 values for 12 chemicals, all tested at least three times in the same vehicle have been analysed by calculating standard deviations (SD) for logEC3 values. The SDs range from 0.08 to 0.22. The overall SD for the 94 logEC3 values is 0.147. Thus the 95% confidence limits (2xSD) for LLNA EC3 values are within a factor of 2, comparable to those for physico-chemical measurements such as partition coefficients and solubility. The residual SDs of Quantitative Mechanistic Models (QMMs) based on physical organic chemistry parameters are similar to the overall SD of the LLNA, indicating that QMMs of this type are unlikely to be bettered for predictive accuracy. 相似文献
8.
9.
10.