全文获取类型
收费全文 | 10913篇 |
免费 | 990篇 |
国内免费 | 839篇 |
专业分类
耳鼻咽喉 | 119篇 |
儿科学 | 72篇 |
妇产科学 | 119篇 |
基础医学 | 1344篇 |
口腔科学 | 136篇 |
临床医学 | 1321篇 |
内科学 | 1792篇 |
皮肤病学 | 91篇 |
神经病学 | 663篇 |
特种医学 | 359篇 |
外国民族医学 | 6篇 |
外科学 | 1111篇 |
综合类 | 1816篇 |
预防医学 | 658篇 |
眼科学 | 295篇 |
药学 | 1136篇 |
10篇 | |
中国医学 | 593篇 |
肿瘤学 | 1101篇 |
出版年
2024年 | 27篇 |
2023年 | 165篇 |
2022年 | 421篇 |
2021年 | 571篇 |
2020年 | 443篇 |
2019年 | 356篇 |
2018年 | 381篇 |
2017年 | 309篇 |
2016年 | 354篇 |
2015年 | 510篇 |
2014年 | 608篇 |
2013年 | 512篇 |
2012年 | 771篇 |
2011年 | 898篇 |
2010年 | 496篇 |
2009年 | 387篇 |
2008年 | 627篇 |
2007年 | 511篇 |
2006年 | 506篇 |
2005年 | 587篇 |
2004年 | 385篇 |
2003年 | 409篇 |
2002年 | 337篇 |
2001年 | 271篇 |
2000年 | 272篇 |
1999年 | 262篇 |
1998年 | 192篇 |
1997年 | 167篇 |
1996年 | 147篇 |
1995年 | 126篇 |
1994年 | 102篇 |
1993年 | 63篇 |
1992年 | 79篇 |
1991年 | 93篇 |
1990年 | 86篇 |
1989年 | 68篇 |
1988年 | 60篇 |
1987年 | 61篇 |
1986年 | 41篇 |
1985年 | 38篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 5篇 |
1978年 | 1篇 |
1968年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
目的:研究正常儿童优势眼视觉诱发电位特征。方法:对47名正常儿童进行全视野刺激多导视觉诱发电位研究。结果:优势眼视觉诱发电位以0_z电极为代表,P_(100)潜伏期较非优势眼缩短(P<0.01),而N_(75)—P_(100)峰峰值较非优势眼增大(P<0.05)。结论:中枢神经系统存在偏利现象,这种偏利现象可能与控制视神经髓鞘优先形成的某种遗传机制有关,或是中枢神经系统突触的局部构造、突触效能的差异。 相似文献
52.
Bojian Zheng Ming-Liang He King-Ling Wong Ching Tung Lum Leo L M Poon Ying Peng Yi Guan Marie C M Lin Hsiang-Fu Kung 《Journal of interferon & cytokine research》2004,24(7):388-390
We sought to investigate the anti-severe acute respiratory syndrome (SARS)-associated coronavirus (SCoV) activities of type I (alpha and beta) and type II (gamma) interferons (IFN) in vitro. Type I IFNs protected cells from cytopathic effects (CPE) induced by SCoV, and inhibited viral genomic RNA replication in FRhk-4 cells (measured by quantitative RT-PCR) in a dose-dependent manner. Intracellular viral RNA copies were reduced 50% by IFN-alpha at a concentration of 25 U/ml and by IFN-beta at a concentration of 14 U/ml. IFN-gamma had fewer effects on inhibition of viral infection and replication. The type I IFN receptor signaling pathway in host cells is mainly involved in the inhibition of SCoV infection and replication. Type I IFNs could be used as potential agents for anti-SARS treatment. 相似文献
53.
背景:应力遮挡效应会导致植入假体修复骨缺损手术失败,其主要原因是由于植入假体的弹性模量大于骨组织弹性模量。目的:分析植入假体弹性模量对应力分布的影响,寻求消除应力遮挡现象的方法。方法:通过CT扫描的方式获取实验犬与人体骨组织的模型,分别对其优化后进行梯度赋值,建立较为可靠的骨骼力学模型,并与植入假体组合后进行有限元仿真。首先,通过对比格犬骨骼模型和人体骨骼模型及其对应的植入假体进行有限元仿真,模拟了不同弹性模量对植入假体修复术后的应力和位移分布情况;其次,分析了较小弹性模量差仍会形成应力遮挡现象的原因,建立了骨骼模型及植入假体模型,确立了材料属性赋予方法;最后,验证了该模型及材料属性赋予方法的可行性,并通过随机选取受力点的方式,定量分析植入假体弹性模量与骨骼弹性模量之间的关系对应力遮挡形成的影响。结果与结论:通过梯度赋值法建立与骨骼力学性质更加接近的实验犬骨骼模型和人体骨骼模型,该方法重建的力学模型与真实骨骼的力学性质更为接近;通过有限元仿真力学测试证明,不同弹性模量植入假体对假体本身与周围骨骼间相对位移的影响较小;另外量化弹性模量对假体植入骨骼后对应力分布的影响,可为后续的相关研究提供帮助。 相似文献
54.
Regulation of the TSC pathway by LKB1: evidence of a molecular link between tuberous sclerosis complex and Peutz-Jeghers syndrome 总被引:13,自引:0,他引:13 下载免费PDF全文
Tuberous sclerosis complex (TSC) and Peutz-Jeghers syndrome (PJS) are dominantly inherited benign tumor syndromes that share striking histopathological similarities. Here we show that LKB1, the gene mutated in PJS, acts as a tumor suppressor by activating TSC2, the gene mutated in TSC. Like TSC2, LKB1 inhibits the phosphorylation of the key translational regulators S6K and 4EBP1. Furthermore, we show that LKB1 activates TSC2 through the AMP-dependent protein kinase (AMPK), indicating that LKB1 plays a role in cell growth regulation in response to cellular energy levels. Our results suggest that PJS and other benign tumor syndromes could be caused by dysregulation of the TSC2/mTOR pathway. 相似文献
55.
Dam J Guan R Natarajan K Dimasi N Chlewicki LK Kranz DM Schuck P Margulies DH Mariuzza RA 《Nature immunology》2003,4(12):1213-1222
The Ly49 family of natural killer (NK) receptors regulates NK cell function by sensing major histocompatibility complex (MHC) class I. Ly49 receptors show complex patterns of MHC class I cross-reactivity and, in certain cases, peptide selectivity. To investigate whether specificity differences result from topological differences in MHC class I engagement, we determined the structure of the peptide-selective receptor Ly49C in complex with H-2K(b). The Ly49C homodimer binds two MHC class I molecules in symmetrical way, a mode distinct from that of Ly49A, which binds MHC class I asymmetrically. Ly49C does not directly contact the MHC-bound peptide. In addition, MHC crosslinking by Ly49C was demonstrated in solution. We propose a dynamic model for Ly49-MHC class I interactions involving conformational changes in the receptor, whereby variations in Ly49 dimerization mediate different MHC-binding modes. 相似文献
56.
CDX2 expression is progressively decreased in human gastric intestinal metaplasia, dysplasia and cancer. 总被引:1,自引:0,他引:1
Qiang Liu Ming Teh Kosei Ito Nilesh Shah Yoshiaki Ito Khay Guan Yeoh 《Modern pathology》2007,20(12):1286-1297
Intestinal metaplasia is a key event in multistep gastric carcinogenesis. CDX2, a master regulator of intestinal phenotype, was shown to play a tumor-suppressive role in colon cancer. However, it was reported to be expressed in nearly all gastric intestinal metaplasia and many gastric cancers. As CDX2 is differentially expressed in normal stomach and intestine, we sought to relate the CDX2 expression to gastrointestinal differentiation along gastric carcinogenesis. The expression of CDX2 protein in gastric intestinal metaplasia, dysplasia and cancer was examined and related to their gastrointestinal differentiation. CDX2 expression was significantly decreased in incomplete intestinal metaplasia, which expresses both gastric mucins (MUC5AC and MUC6) and intestinal mucin (MUC2), compared with complete intestinal metaplasia, which expresses intestinal mucin (MUC2) only. Although incomplete intestinal metaplasia morphologically resembles colon, its CDX2 expression was apparently lower than that in the normal colon. Moreover, CDX2 expression was progressively reduced in gastric dysplasia and cancer. The CDX2 expression in gastric cancer was also inversely correlated with the expression of gastric mucins. As incomplete intestinal metaplasia is associated with higher risk of gastric cancer, its lower CDX2 expression compared with that in complete intestinal metaplasia and normal colon epithelium resolved the current contradiction between the tumor-suppressive role of CDX2 in the colon and the high prevalence of CDX2 in intestinal metaplasia. Further decrease of CDX2 expression in gastric dysplasia and cancer suggests that CDX2 plays a similar anticarcinogenic role in intestinal metaplasia as it does in colon. Intestinal metaplasia or dysplasia with low expression of CDX2 may serve as predictive markers for gastric cancer. 相似文献
57.
58.
Huang Y Zhao N He L Wang L Liu Z You M Guan F 《Journal of clinical microbiology》2005,43(3):1451-1455
A gram-positive, coryneform bacterium was isolated from swollen scleromata of a dermatosis patient. An analysis of its phenotypic, chemotaxonomic, and genotypic characteristics showed that this bacterium is closely associated with Arthrobacter oxydans and Arthrobacter polychromogenes but that it belongs to a distinct species, for which the name Arthrobacter scleromae sp. nov. is proposed. 相似文献
59.
Correlation of AIB1 overexpression with advanced clinical stage of human colorectal carcinoma 总被引:7,自引:0,他引:7
AIB1, a member of the steroid receptor coactivator 1 family, has been cloned on 20q12 and is a candidate oncogene in human breast cancer. It is commonly amplified and overexpressed in several types of human cancers. In this study, we examined the expression of AIB1, as related to clinicopathologic features, in 85 human colorectal cancers (CRCs). The status of the number of AIB1 copies, p53 expression, and DNA ploidy was also analyzed. The overexpression of AIB1 was detected in 35% of CRCs. Amplification of AIB1 was observed in 10% of CRCs. In addition, the overexpression of AIB1 was observed more frequently in CRCs in later clinical stages (T3 N1 M0/T3 N0 2M1), compared with that in T3 N0 M0 stage (P < .05). These results suggest that overexpression of AIB1 might provide a selective advantage for the developmental growth and/or progression of subsets of CRCs. In addition, a significant correlation (P < .05) of overexpression of AIB1 with p53 overexpression as well as with aneuploid DNA content was observed in these CRCs. The overexpression of p53 was also correlated significantly with CRC DNA ploidy (P < .05). Furthermore, there was a substantial population of CRCs showing overexpression of both AIB1 and p53 protein and all had aneuploid DNA content; most of these were in the later clinical stage. These findings suggest a possible convergence of AIB1 with a pathway involving p53, which might induce chromosomal instability and affect the clinical phenotype of a subset of CRCs. 相似文献
60.
目的探讨抑郁障碍患者与家属的家庭亲密度适应性和情绪状况,为抑郁障碍患者的健康教育及家庭干预提供科学有效的理论依据。方法选择2006年6~9月在北京大学第六医院就诊的抑郁障碍患者95例及共同陪伴的直系家属95例为调查对象。采用家庭亲密度和适应性量表中文版(FACES-CV)、Zung氏焦虑自评量表和Zung氏抑郁自评量表。结果1患者的家庭亲密度得分与国内常模一致(P>0.05),但适应性得分低于国内常模(P<0.01);焦虑、抑郁得分高于国内常模(P<0.01)。家属的家庭亲密度得分高于国内常模(P<0.01),适应性得分低于国内常模(P<0.01)。家属的焦虑得分与国内常模一致(P>0.05),但抑郁得分高于国内常模(P<0.05)。2家庭模式分型构成比:中间型47.9%,平衡性26.3%,极端型25.8%。患者的家庭"拱极模式"以"僵硬—松散型"居多,家属则以"自由—缠结型"居多。3家庭亲密度与患者的家属的文程化度有关,相关系数范围(r=0.21~0.26,P<0.05)、与家庭人数呈负相关(r=-0.21,P<0.01);与患者及家属的焦虑、抑郁情绪呈显著负相关,相关系数范围(r=-0.30~0.37,P<0.01);家庭适应性与患者的年龄(r=0.28,P<0.01)、文化程度(r=0.34,P<0.01)有关。与家属的年龄(r=0.26,P<0.05)文化程度(r=0.22,P<0.05)有关。与患者和家属的焦虑、抑郁情绪呈显著负相关,相关系数范围(r=-0.30~-0.42,P<0.01)。结论家庭亲密度适应性与患者和家属的文化程度、焦虑、抑郁情绪有关,家庭亲密度与患者的家庭人数有关,家庭适应性与患者和家属的年龄有关。 相似文献