全文获取类型
收费全文 | 90058篇 |
免费 | 8874篇 |
国内免费 | 7328篇 |
专业分类
耳鼻咽喉 | 662篇 |
儿科学 | 828篇 |
妇产科学 | 987篇 |
基础医学 | 10729篇 |
口腔科学 | 1628篇 |
临床医学 | 13021篇 |
内科学 | 13183篇 |
皮肤病学 | 724篇 |
神经病学 | 5337篇 |
特种医学 | 3172篇 |
外国民族医学 | 56篇 |
外科学 | 8378篇 |
综合类 | 15464篇 |
现状与发展 | 22篇 |
一般理论 | 13篇 |
预防医学 | 5816篇 |
眼科学 | 2954篇 |
药学 | 9292篇 |
102篇 | |
中国医学 | 5907篇 |
肿瘤学 | 7985篇 |
出版年
2024年 | 322篇 |
2023年 | 1537篇 |
2022年 | 4320篇 |
2021年 | 5222篇 |
2020年 | 3969篇 |
2019年 | 3246篇 |
2018年 | 3441篇 |
2017年 | 2886篇 |
2016年 | 2832篇 |
2015年 | 4307篇 |
2014年 | 5307篇 |
2013年 | 4486篇 |
2012年 | 6590篇 |
2011年 | 7637篇 |
2010年 | 4591篇 |
2009年 | 3598篇 |
2008年 | 4607篇 |
2007年 | 4477篇 |
2006年 | 4654篇 |
2005年 | 4674篇 |
2004年 | 2760篇 |
2003年 | 2689篇 |
2002年 | 2240篇 |
2001年 | 1949篇 |
2000年 | 2071篇 |
1999年 | 2179篇 |
1998年 | 1459篇 |
1997年 | 1386篇 |
1996年 | 1111篇 |
1995年 | 1022篇 |
1994年 | 848篇 |
1993年 | 536篇 |
1992年 | 601篇 |
1991年 | 511篇 |
1990年 | 467篇 |
1989年 | 422篇 |
1988年 | 347篇 |
1987年 | 297篇 |
1986年 | 229篇 |
1985年 | 178篇 |
1984年 | 81篇 |
1983年 | 50篇 |
1982年 | 42篇 |
1981年 | 36篇 |
1980年 | 24篇 |
1979年 | 21篇 |
1964年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Lei Wang Moyi Sun Yuegui Jiang Lianjia Yang Delin Lei Chao Lu Yinghua Zhao Pu Zhang Yaowu Yang Jianhu Li 《Journal of oral and maxillofacial surgery》2006,64(4):636-641
PURPOSE: Perineural invasion is a frequent occurrence in salivary adenoid cystic carcinoma (ACC) and may prevent complete surgical resection. Studies have indicated that nerve growth factor (NGF) and its high-affinity receptor tyrosine kinase A (TrkA) may play a role in perineural invasion in several malignancies in which perineural invasion is observed. The present study was conducted to investigate the expression of NGF and TrkA in salivary ACC and to examine the effects of NGF on adhesion, migration and invasion capacities of a salivary ACC cell line (SACC-83) in vitro. PATIENTS AND METHODS: Expression of NGF and TrkA was explored using immunohistochemistry in paraffin-embedded tissues of 32 cases of salivary ACC. The effects of NGF on in vitro adhesion, migration, and invasion capacities of the SACC-83 cell line were examined using an MTT assay and a modified Boyden chamber assay respectively. RESULTS: In ACC specimens, 31 (96.9%) and 32 (100%) tumors showed immunoreactivity for NGF and TrkA respectively. Significant correlations were found between NGF/TrkA expression levels and perineural invasion (P < .05). In cell adhesion assay, the percent adherences of SACC-83 cells co-cultured with 25 ng/ml NGF at 1.5 hours and 5, 25 ng/ml NGF at 6 hours were significantly higher than that co-cultured with 0 ng/ml NGF (P < .05). However, high concentration of NGF (500 ng/ml) resulted in a significant inhibition of invasion (P < .05). CONCLUSION: Overexpression of NGF and TrkA in human salivary ACC tissues may constitute a reason for perineural invasion in salivary ACC. 相似文献
12.
Five commercially available nitropolyclyclic aromatic hydrocarbons (nitro-PAH), namely, 4-nitrobiphenyl, 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene, and 2,7-dinitrofluorene, were exposed under restricted sunlight in the open air. The direct-acting mutagenicities of the samples after an exposure of 45 days were measured in order to compare them with those of the original samples in the Ames Salmonella typhimurium bioassay. It was found that the mutagenicities of some nitro-PAH do not change significantly while the mutagenicities of others increase or decrease after exposure. A preliminary study of nitro-PAH reaction products after exposure using GC, GC/MS, and FT-IR is also reported. 相似文献
13.
Viral markers were studied in 79 cases of viral hepatitis with hepatic failure. The results were shown as follows: 8 cases were positive for anti-HAV IgM (10.12%); 76 cases positive for HBsAg or anti-HBc IgM (96.20%) and 41 cases positive for anti-HCV antibodies (51.89%). Among those with anti-HCV positive, 35 cases were co-infected with HBV, 5 cases with HAV and/or HCV, only one was infected with HCV alone 2 cases were HD-Ag positive (2.52%) and one not identified (1.27%). With the reference of clinical findings, patients co-infected with HBV/HCV or anti-HBc IgM positive were more critical and usually entail higher mortality. In cases with HCV co-infections, the positive HBV replication markers seems to be reduced. Hepatic failure without HBV replicative markers had a high rate of hepatic coma as well as poor outcome. 相似文献
14.
目的 :探讨外周血单个核细胞 (PBMC)内上游信号分子及核因子 κB(NF κB)在烧伤后炎症级联反应中的作用。 方法 :体外检测在烧伤血浆作用下的PBMC内游离Ca2 及NF κB活化的变化 ,观察钙通道阻断药对NF κB活化及IL 6、NO表达水平的调控作用。 结果 :不同时相点的烧伤血浆可使体外PBMC内Ca2 明显增加 ,培养的PBMC核内NF κB的积聚明显增加 ,培养上清中NO和IL 6高表达。应用尼莫通 (Nimodipine)和丹曲林 (Dantrium)对NF κB的活化有调节作用 ,对IL 6和NO亦有下调作用。 结论 :烧伤血浆可使PBMC内信号分子浓度明显增高 ,NF κB过度活化 ,并易位进入细胞核内 ,NF κB介导的促炎性细胞因子和NO过度表达。两种钙通道阻断药有调控细胞内信号转导的作用 ,对烧伤后全身炎症反应综合征 (SIRS)可能有防治作用 相似文献
15.
浅谈基因治疗的现状及其面临的困境 总被引:1,自引:0,他引:1
基因治疗将在未来的疾病治疗中扮演重要的角色,然而这一新颖的技术却面临着诸多问题,本文论述了基因治疗的发展现状及其所面临的技术难题。 相似文献
16.
The measurement of amniotic fluid (AF) acetylcholinesterase isoenzyme (AChEI) is a relatively new method for early diagnosis of open neural tube defects (NTDs). As quantitative methods are of unproven reliability at present, the authors used a high resolving power qualitative method-vertical slab polyaerylamide gel electrophoresis. The benefits of this technique are: simplicity of operation, accuracy, unsophisticated equipment, and easily available reagents. Combined results of 9 NTDs studies revealed that samples from early pregnancy gave more accurate results than those from late pregnancy. 相似文献
17.
赵世峰 《世界急危重病医学杂志》2006,3(3):1257-1257
目的:通过尸体解剖检查结果来观测临床死亡诊断与实际死凶之间的差异,本研究中的死亡病例均发生在急诊科并向苏格兰地方检查院上报,随后进行尸检。方法:这是在格拉斯哥某医院急诊科进行的一个为期1年的前瞻性研究,所有入选病例系来院前死亡和在急诊科死亡的患者。由有经验的急诊科医师在场判断死亡原因,然后与尸枪结果确定的真正死因进行对照,比较两者之间的差异。 相似文献
18.
19.
20.