全文获取类型
收费全文 | 3574篇 |
免费 | 392篇 |
国内免费 | 249篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 16篇 |
妇产科学 | 62篇 |
基础医学 | 450篇 |
口腔科学 | 129篇 |
临床医学 | 439篇 |
内科学 | 535篇 |
皮肤病学 | 41篇 |
神经病学 | 182篇 |
特种医学 | 101篇 |
外国民族医学 | 2篇 |
外科学 | 316篇 |
综合类 | 594篇 |
现状与发展 | 3篇 |
预防医学 | 284篇 |
眼科学 | 88篇 |
药学 | 443篇 |
2篇 | |
中国医学 | 224篇 |
肿瘤学 | 278篇 |
出版年
2024年 | 10篇 |
2023年 | 61篇 |
2022年 | 146篇 |
2021年 | 208篇 |
2020年 | 140篇 |
2019年 | 141篇 |
2018年 | 146篇 |
2017年 | 132篇 |
2016年 | 145篇 |
2015年 | 183篇 |
2014年 | 203篇 |
2013年 | 167篇 |
2012年 | 268篇 |
2011年 | 271篇 |
2010年 | 164篇 |
2009年 | 119篇 |
2008年 | 164篇 |
2007年 | 160篇 |
2006年 | 192篇 |
2005年 | 169篇 |
2004年 | 109篇 |
2003年 | 95篇 |
2002年 | 87篇 |
2001年 | 89篇 |
2000年 | 98篇 |
1999年 | 107篇 |
1998年 | 57篇 |
1997年 | 76篇 |
1996年 | 51篇 |
1995年 | 36篇 |
1994年 | 35篇 |
1993年 | 26篇 |
1992年 | 32篇 |
1991年 | 33篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 3篇 |
排序方式: 共有4215条查询结果,搜索用时 13 毫秒
81.
82.
70岁以上住院老年慢性病病人抑郁和焦虑的调查 总被引:1,自引:0,他引:1
随着医学科学技术的飞速发展和人民物质精神生活水平的日益提高,我国人口的平均预期寿命不断增长,现已接近70岁。据统计:目前我国老年病人口(我国以60岁以上为老年病人)总数已近I.3亿,约占总人口数的10.09%,而75岁以上老年病人以每年平均3.62%的速度增长,预测到2025年将上升到20%,2050年将达到顶峰25.5%。老年人是慢性病的主要患病人群。因此,本研究针对70岁以上患慢性病的住院普通老年人和住院离休干部进行调查,采用Brink老年抑郁量表(GDS)、Zung焦虑自评量表(SAS),以了解住院老年人中存在的焦虑、抑郁情况以及分析两组病人的性别、年龄、文化程度、婚姻状况、个人习惯和经济收入情况。现将结果报道如下。[第一段] 相似文献
83.
84.
85.
86.
Chen-qing Liu Xiao-ting Cheng Yu-hua Zhu Wei-dong Shen Bo-wen Bian Ju-yang Cao 《Acta oto-laryngologica》2015,135(5):451-458
Conclusion: The hearing conditions of the centenarians were quite poor as regards hearing thresholds and speech detection ability. Objective: To investigate hearing conditions of centenarians. Methods: A total of 54 centenarians in Rizhao and Linyi Districts in Shandong Province were investigated to assess hearing conditions of centenerians comprehensively by questionnaire investigation, pure-tone audiometry, acoustic immitance, intelligence evaluation, and speech detection scores. Also, 135 individuals were recruited as controls and divided into four groups according to their age: 45–59 years, 60–69 years, 70–79 years, and 80–89 years. Results: The hearing thresholds of the centenarians were dramatically higher than those of the control group (p < 0.05) and all centenarians suffered moderate to profound hearing loss according to the World Health Organization (WHO) criteria. Few centenarians had normal level of speech detection scores. All centenarians showed descending hearing curve, and the hearing threshold of the male centenarians at 8000 Hz was higher than that of the females (p = 0.047). There was a significant air–bone conduction gap in the centenarians (p < 0.05). 相似文献
87.
Li Yuan Wu Xiaodong Huang Yan Bian Dongliang Jiang Lei 《Annals of nuclear medicine》2020,34(5):314-321
Annals of Nuclear Medicine - Lung adenosquamous carcinoma (ASC) is a rare histological subtype of non-small cell lung cancer (NSCLC). Due to its rarity, the studies about 18F-FDG PET/CT in this... 相似文献
88.
Muhamed Hadzipasic Babak Tahvildari Maria Nagy Minjuan Bian Arthur L. Horwich David A. McCormick 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(47):16883-16888
Amyotrophic lateral sclerosis (ALS; Lou Gehrig’s disease) affects motor neurons (MNs) in the brain and spinal cord. Understanding the pathophysiology of this condition seems crucial for therapeutic design, yet few electrophysiological studies in actively degenerating animal models have been reported. Here, we report a novel preparation of acute slices from adult mouse spinal cord, allowing visualized whole cell patch-clamp recordings of fluorescent lumbar MN cell bodies from ChAT-eGFP or superoxide dismutase 1-yellow fluorescent protein (SOD1YFP) transgenic animals up to 6 mo of age. We examined 11 intrinsic electrophysiologic properties of adult ChAT-eGFP mouse MNs and classified them into four subtypes based on these parameters. The subtypes could be principally correlated with instantaneous (initial) and steady-state firing rates. We used retrograde tracing using fluorescent dye injected into fast or slow twitch lower extremity muscle with slice recordings from the fluorescent-labeled lumbar MN cell bodies to establish that fast and slow firing MNs are connected with fast and slow twitch muscle, respectively. In a G85R SOD1YFP transgenic mouse model of ALS, which becomes paralyzed by 5–6 mo, where MN cell bodies are fluorescent, enabling the same type of recording from spinal cord tissue slices, we observed that all four MN subtypes were present at 2 mo of age. At 4 mo, by which time substantial neuronal SOD1YFP aggregation and cell loss has occurred and symptoms have developed, one of the fast firing subtypes that innvervates fast twitch muscle was lost. These results begin to describe an order of the pathophysiologic events in ALS.Amyotrophic lateral sclerosis (ALS; Lou Gehrig’s disease) is a progressive and usually lethal neurodegenerative condition prominently featuring loss of motor neurons (MNs) and muscle denervation (1–3). Inherited forms of ALS, accounting for ∼10% of cases, potentially inform about disease mechanisms, including: protein folding and quality control [e.g., mutant superoxide dismutase 1 (SOD1), ubiquilin2, and VCP]; RNA binding proteins (e.g., TDP43, FUS, and HNRNPA1); or a DNA expansion (C9ORF72 hexanucleotide expansion). The clinical courses of the various heritable forms and the 90% of cases that are considered sporadic are not distinct, however, reflecting a potentially shared progressive loss of MNs and motor circuit dysfunction (4).ALS has been modeled in mice that are transgenic for a variety of mutant forms of SOD1, allowing for the study of the trajectory of the condition at various time points (5, 6). Among the studies conducted to date are a number addressing electrophysiological changes. From these studies, however, there does not appear to be a clear consensus on the changes that occur in MNs before and during the development of symptoms (7). For example, whereas research on the neuromuscular junction has revealed preferential denervation of fast twitch (type IIb) muscle fibers (8–10), the relationship of this selective susceptibility at the muscle level to pathophysiologic change in the spinal cord is not clear.A major challenge to understanding spinal cord physiology of the mouse models of ALS arises from difficulty in distinguishing the individual features of neurons in the anatomically and physiologically heterogeneous motor system. For example, the usefulness of in vivo recordings requires ensuring adequate sampling of anatomically and functionally heterogeneous spinal cord MNs. For the ex vivo alternative, slice physiology is challenging because most mouse models develop disease after 1 mo of age, a time when spinal cord tissue becomes more sensitive to ischemia (11, 12), making isolation of viable slices difficult. In addition, the spinal cord becomes heavily myelinated in the first few weeks of postnatal life (13), making visualization of individual neurons difficult. Hence, most research regarding cellular electrophysiology in mouse models of ALS has been carried out with primary cultures of embryonic (E13–14) spinal cord MNs (14) or induced pluripotent stem (iPS) cell-derived MNs (15). Although they provide a basis for further study, these models may lack the changes that occur progressively in the context of an intact spinal cord. These models may also lack the diversity of MN physiology present in the mature spinal cord.Here we studied a transgenic strain of ALS mice, G85R SOD1YFP (16), that develops motor symptoms by ∼3 mo of age, associated with progressive accumulation of aggregates in MN cell bodies (from ∼1 mo of age), attended by MN cell loss. The mice paralyze uniformly by 5–6 mo of age. We first developed, using ChAT- EGFP mice that express GFP fluorescence in MNs (17), an acute slice preparation of adult mouse spinal cord that yielded healthy MNs in animals up to and beyond 6 mo of age, readily visualized by their fluorescence, enabling whole cell patch-clamp recordings when coupled with differential interference contrast (DIC) imaging. This preparation allowed extensive characterization of normal MN electrophysiology and enabled grouping of MNs, distinguishing four firing types. We then recorded from MNs in slices from ALS animals at two time points: during the course of aggregation at 2–3 mo of age, before symptoms, and after the onset and initial progression of symptoms at 4 mo of age. At the early time, the four distinct clusters of MNs were present, albeit the fastest firing type (cluster 4) exhibited a significant hyperpolarization. At the later time point, this firing type was no longer detectable, with only the other three types observable, the fastest of which (cluster 3) was now hyperpolarized. Retrograde tracing from fast and slow twitch muscles of the lower extremity revealed that aggregates form preferentially in MN cell bodies attached to fast twitch muscle. These observations suggest a possible sequence of events in which hyperpolarization of the cluster 4 MNs, innervating fast twitch muscle, is associated with aggregate formation in these neurons, which then die, denervating fast twitch muscle. 相似文献
89.
ZhaoGuo Hong Chu Zheng Bi Luo Xin You HeDong Bian Hong Liang ZhenFeng Chen FuPing Huang 《RSC advances》2020,10(11):6297
Based on 1,2-dimethoxyphenyl (veratrole, open) and 1,2-methylenedioxyphenyl (pepper ring, close)-derived pyridine–triazole analogues, two groups of copper(ii) complexes, namely, Group I(C1–C3) and Group II(C4–C6) were synthesized and fully characterized. All ligands and complexes were tested in vitro by MTT assays on seven tumour cell lines (T24, Hep-G2, Sk-Ov-3, MGC-803, HeLa, A549 and NCI-H460) and one normal liver cell line (HL-7702). Surprisingly, the pepper-ring-derived complexes (C4–C6) showed significantly enhanced cytotoxicity compared with the 1,2-bimethoxyphenyl ring-derived complexes (C1–C3) and the standard anticancer drug cisplatin. Cellular uptake assays indicated that the Cu accumulation was consistent with cytotoxicity. In addition, flow cytometry and western blot analysis showed that the apoptosis of the leading complex C4 may be induced by the Bcl-2 family-mediated proteins through the mitochondrial dysfunction pathway. Furthermore, UV-vis and fluorescence spectroscopy assays revealed that C4 has stronger insertion-binding interactions with CT-DNA than C1 and the fluorescence of C1 and C4 with BSA is mainly quenched by static quenching.The pepper ring-modified complexes (Group II, C4–C6) exhibited significant antitumor activity than veratrole-modified complexes (Group I, C1–C3) towards several cancer cells with IC50 ranging from 3.45 to 8.59 μM. 相似文献
90.
Jianya Zhang Min Zhou Dongmin Wu Lifeng Bian Yukun Zhao Hua Qin Wenxian Yang Yuanyuan Wu Zhiwei Xing Shulong Lu 《RSC advances》2021,11(26):15632
Due to the wide applications of blue and red photodetectors, dual-wavelength (blue/red) photodetectors are promising for future markets. In this work, a dual-wavelength photodetector based on vertical (In,Ga)N nanowires and graphene has been fabricated successfully. By using the transparent graphene, both blue and red responses can be clearly detected. The rise time of response can reach 3.5 ms. Furthermore, the underlying mechanism of double responses has also been analyzed. The main reason contributing to the dual-wavelength response could be the different diameters of nanowires, leading to different In components within (In,Ga)N sections.A dual-wavelength (blue/red) photodetector based on vertical (In,Ga)N nanowires and graphene has been fabricated successfully, which is promising for wide applications. The rise time of the response can reach 3.5 ms. 相似文献