全文获取类型
收费全文 | 325482篇 |
免费 | 29307篇 |
国内免费 | 22887篇 |
专业分类
耳鼻咽喉 | 2999篇 |
儿科学 | 3436篇 |
妇产科学 | 4925篇 |
基础医学 | 39973篇 |
口腔科学 | 5503篇 |
临床医学 | 45295篇 |
内科学 | 49792篇 |
皮肤病学 | 3089篇 |
神经病学 | 18417篇 |
特种医学 | 12006篇 |
外国民族医学 | 213篇 |
外科学 | 33395篇 |
综合类 | 50242篇 |
现状与发展 | 76篇 |
一般理论 | 20篇 |
预防医学 | 19679篇 |
眼科学 | 9643篇 |
药学 | 32859篇 |
342篇 | |
中国医学 | 17796篇 |
肿瘤学 | 27976篇 |
出版年
2024年 | 1564篇 |
2023年 | 5135篇 |
2022年 | 13083篇 |
2021年 | 16431篇 |
2020年 | 12359篇 |
2019年 | 10987篇 |
2018年 | 11488篇 |
2017年 | 10016篇 |
2016年 | 9438篇 |
2015年 | 14368篇 |
2014年 | 17804篇 |
2013年 | 15354篇 |
2012年 | 22871篇 |
2011年 | 25804篇 |
2010年 | 15901篇 |
2009年 | 12248篇 |
2008年 | 17012篇 |
2007年 | 17020篇 |
2006年 | 17049篇 |
2005年 | 16773篇 |
2004年 | 10662篇 |
2003年 | 9756篇 |
2002年 | 8440篇 |
2001年 | 7466篇 |
2000年 | 8272篇 |
1999年 | 9007篇 |
1998年 | 5475篇 |
1997年 | 5498篇 |
1996年 | 4332篇 |
1995年 | 3923篇 |
1994年 | 3213篇 |
1993年 | 2097篇 |
1992年 | 2827篇 |
1991年 | 2415篇 |
1990年 | 2117篇 |
1989年 | 1861篇 |
1988年 | 1563篇 |
1987年 | 1352篇 |
1986年 | 1107篇 |
1985年 | 912篇 |
1984年 | 526篇 |
1983年 | 373篇 |
1982年 | 242篇 |
1981年 | 238篇 |
1980年 | 188篇 |
1979年 | 221篇 |
1978年 | 82篇 |
1977年 | 89篇 |
1974年 | 102篇 |
1973年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
王雪娟 《中华实用中西医杂志》2006,19(7):746-746
现将我院2002-2005年收治住院的急性心肌梗死患者56例的心理干预及护理体会,报告如下: 相似文献
42.
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
43.
44.
N Wang 《中华结核和呼吸杂志》1991,14(2):79-82, 126
A prospective study was conducted with patients with pulmonary infections who were consecutively admitted to the three community hospitals in Benghu from July 1986 to May 1987, and to the children's hospital in Nanjing from September 1986 to January 1987. Antibodies to Lpi-8, Lm, Ld, and Lg were measured by the micro-agglutination test. During the study period, 150 adult patients (100 pairs sera) and 212 control healthy people and 110 pairs sera of childhood patients and 173 children without respiratory tract infections were investigated. The diagnosis of legionellosis was based on seroconversion (fourfold rise in titer to greater than 1:32 or static titer of greater than 1:32) and clinical and radiographic features of legionnaires' disease. About 11% legionella infection in hospitalized adult patients with pulmonary infections, and about 5.45% in children with atypical pneumonias. 相似文献
45.
46.
Y Taki T Morimoto A Tanaka M Noguchi W Y Wang T Nishihira K Nishikawa K Mori K Ozawa 《The Journal of surgical research》1990,48(1):56-60
Ketogenic capacity of mitochondria from the remnant liver of 70% hepatectomized rats was studied in relation to mitochondrial phosphorylative activity. Ketogenic capacity increased to a maximum of 6.04 +/- 0.39 from 3.84 +/- 0.13 of control, with an enhancement of mitochondrial phosphorylative activity 6 hr after hepatectomy, and then decreased to normal levels within 24 hr. Adenylate energy charge, (ATP + 1/2ADP)/(ATP + ADP + AMP), of the remnant liver decreased to 0.825 +/- 0.006 as compared to 0.849 +/- 0.002 of control 6 hr after operation. At 12 hr, total ketone body concentrations of the arterial blood increased concomitant with a fall in ketone body ratio (acetoacetate/3-hydroxybutyrate) which reflects the decreased liver mitochondrial redox (NAD+/NADH) state. These findings suggest that an enhancement of mitochondrial fatty acid oxidation and ketogenesis occurs concomitant with an enhancement of mitochondrial phosphorylative activity in the remnant liver in response to a decreased energy charge after 70% hepatectomy. 相似文献
47.
Sodium saccharin, at high doses in the diet, has been reported to cause hyperplasia of the forestomach (squamous portion of stomach), at the limiting ridge in F344 rats, in addition to its potential to induce proliferative effects on the urinary bladder epithelium. We have characterized this hyperplasia of the squamous epithelium of the forestomach at the limiting ridge in F344 and Sprague-Dawley rats given various doses of sodium saccharin for 4 to 95 wk. With increasing doses of sodium saccharin, the limiting ridge of the forestomach showed dose-related morphological changes: basal-cell hyperplasia, early papillary hyperplasia with basal-cell hyperplasia and papillary hyperplasia. Calcium saccharin in Prolab diet caused hyperplasia of the forestomach at the limiting ridge, similar to that caused by sodium saccharin. The severity of hyperplasia was influenced by the type of diet and by the strain of rats. AIN-76A diet without added sodium saccharin caused basal-cell hyperplasia in F344 rats, whereas Prolab, Purina and NIH-07 diets without added sodium saccharin had little or no effect on the forestomach. The effect of AIN-76A diet alone persisted through 95 wk of feeding without any evidence of tumour formation. In Sprague-Dawley rats, which appeared more sensitive to effects on the forestomach than F344 rats, Prolab 3200 and Purina diets without sodium saccharin caused basal-cell hyperplasia in more than half of the treated rats. The forestomach hyperplasia associated with AIN-76A or saccharin administration appears to be mild, limited in extent to the limiting ridge, and not associated with carcinogenesis. 相似文献
48.
Calcitonin gene-related peptide (CGRP) causes vasorelaxation in rat aorta involving endothelium/nitric oxide (NO)-dependent elevations of both cAMP and cGMP levels. When endothelium is removed, preincubation with exogenous NO uncovers and potentiates direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP. This enhancing effect of NO potentially involves elevation of cGMP and inhibition of Type III (cGMPinhibitable) phosphodiesterase, causing accumulation of cAMP. However, NO may have other actions. The aim of the present study was to determine if brain natriuretic peptide (BNP), which elevates cGMP levels independent of NO, could enhance cAMP accumulations and vasorelaxations induced by CGRP in rat aortic rings denuded of endothelium. When added separately, neither CGRP (100 nM) nor BNP (10 nM) altered cAMP levels. When added in combination, CGRP (100 nM) and BNP (10 nM) significantly elevated cAMP levels (from control of 0.95 ± 0.08 to 1.53 ± 0.09 pmol/mg protein) at 2 min. BNP (10 nM) elevated cGMP levels 10-fold at 2 min and this response was not altered by co-administration of CGRP (100 nM).Pretreatment with BNP at concentrations as low as 1 nM in endothelium-denuded aortic rings greatly enhanced the direct vasorelaxant effects of CGRP (100 nM) (from control of 0% to 57.6 ± 6.8% relaxation of phenylephrineprecontractions). Our findings indicate that BNP enhances direct (endothelium-independent) cAMP elevations and vasorelaxations caused by CGRP in rat aorta, thus supporting the concept that cGMP inhibits cAMP metabolism and enhances CGRP-induced responses in aortic smooth muscle cells. 相似文献
49.
胫骨延长术是矫治小儿麻痹后遗症下肢短缩最常见的术式,但如何恢复或改善术后的功能,目前尚无一套系统的程序。本文作者根据自行设计的胫骨延长休后功能康复的临床观察,作较系统地介绍,并就该程序的合理性,进行了讨论与论证。 相似文献
50.
我院治疗66例心间隔缺损的病例中,有4例合并哑性动脉导管未闭(简称PDA),发生率6%。全组病例术前均无PDA临床体征,1例术前再次复查心脏彩超时发现,其余3例均漏诊。1例先处理PDA,3例在纠正心内畸形同时处理PDA。心间隔缺损合并哑性PDA容易漏诊,但有其临床特点,手术可先处理PDA,或在体外循环下处理PDA。 相似文献