全文获取类型
收费全文 | 49477篇 |
免费 | 3620篇 |
国内免费 | 2028篇 |
专业分类
耳鼻咽喉 | 174篇 |
儿科学 | 855篇 |
妇产科学 | 506篇 |
基础医学 | 7111篇 |
口腔科学 | 514篇 |
临床医学 | 3764篇 |
内科学 | 13701篇 |
皮肤病学 | 649篇 |
神经病学 | 3331篇 |
特种医学 | 942篇 |
外国民族医学 | 2篇 |
外科学 | 3770篇 |
综合类 | 5340篇 |
现状与发展 | 5篇 |
预防医学 | 2944篇 |
眼科学 | 879篇 |
药学 | 6958篇 |
6篇 | |
中国医学 | 1580篇 |
肿瘤学 | 2094篇 |
出版年
2023年 | 477篇 |
2022年 | 938篇 |
2021年 | 1193篇 |
2020年 | 1191篇 |
2019年 | 1857篇 |
2018年 | 1841篇 |
2017年 | 1651篇 |
2016年 | 1639篇 |
2015年 | 1786篇 |
2014年 | 2943篇 |
2013年 | 3437篇 |
2012年 | 2727篇 |
2011年 | 3001篇 |
2010年 | 2278篇 |
2009年 | 2230篇 |
2008年 | 2204篇 |
2007年 | 2428篇 |
2006年 | 2128篇 |
2005年 | 1852篇 |
2004年 | 1638篇 |
2003年 | 1522篇 |
2002年 | 1272篇 |
2001年 | 1130篇 |
2000年 | 980篇 |
1999年 | 902篇 |
1998年 | 761篇 |
1997年 | 826篇 |
1996年 | 618篇 |
1995年 | 621篇 |
1994年 | 537篇 |
1993年 | 412篇 |
1992年 | 369篇 |
1991年 | 294篇 |
1990年 | 228篇 |
1989年 | 203篇 |
1988年 | 169篇 |
1987年 | 155篇 |
1985年 | 489篇 |
1984年 | 581篇 |
1983年 | 456篇 |
1982年 | 421篇 |
1981年 | 410篇 |
1980年 | 371篇 |
1979年 | 327篇 |
1978年 | 279篇 |
1977年 | 213篇 |
1976年 | 252篇 |
1975年 | 250篇 |
1974年 | 200篇 |
1973年 | 177篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
《Journal of labelled compounds & radiopharmaceuticals》2006,49(4):339-343
Condensation of thiourea 1 with diethyl malonate 2 in the presence of sodium methoxide furnished 4,6‐dihydroxy‐2‐mercaptopyrimidine 3 . Compound 3 on methylation with diazomethane followed by oxidation with H5IO6/CrO3 in ethyl acetate gave 4,6‐dimethoxy‐2‐methylsulphonylpyrimidine 5 . Compound 5 on condensation with 2‐mercapto‐6‐chlorobenzoic acid in the presence of a phase transfer catalyst, tetrabutylammonium bromide and sodium carbonate gave the title compound – pyrithiobac‐sodium 6 with an overall yield of > 35% starting from thiourea. Following the above standardized procedure, using [14C]‐thiourea in lieu of thiourea, 14C labelled product 6 , was synthesized with an overall radiochemical yield > 30% (with respect to [14C]‐thiourea) for further evaluations of environmental fate of 6 , in soils and plants. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
6.
Eijiro Morita Torao Tanaka Tetsuya Nakamura Fumitaka Terabe Ichiro Hirata Kenichi Katsu Masakazu Takazoe Akira Terano 《Digestive endoscopy》2006,18(4):263-268
Background and Aims: Video capsule endoscopy (VCE) has become increasingly important as a simple method for observing the entire small intestine. The indications for VCE are obscure gastrointestinal bleeding and investigation of Crohn’s disease (CD). However, the correlation between endoscopic findings obtained by VCE and clinical findings in known cases of CD is not clear, and we therefore investigated this in the present study. Patients and methods: In 30 patients with known CD (Crohn’s disease activity index [CDAI] 0–420; median = 158.3), double contrast enteroclysis (ENT) was performed 1–3 weeks prior to VCE. The relationship between the VCE findings and hematological analysis/CDAI was examined. Results: In 17 of 30 patients, the entire small intestine could be investigated by VCE, whereas in the remaining 13 patients the terminal ileum could not be investigated. The following exhibited positive correlations: total lesions and CDAI (correlation coefficient values: rs = 0.661, adjusted P < 0.0061), ulcers and C‐reactive protein (CRP) (rs = 0.607, adjusted P < 0.0061), total lesions and CRP (rs = 0.604, adjusted P < 0.0061). Conclusions: Analysis with VCE suggests that CDAI and CRP indicate the activity of intestinal lesions in patients with known CD, and that CRP, in particular, is associated with the activity of ulcerative lesions of the intestine. This may contribute to revised guidelines for VCE in the future. 相似文献
7.
[目的]研究超敏C反应蛋白(hs-CRP)、总抗氧化状态(TAS)联合血脂检测在早老性痴呆症诊断中的应用价值:[方法]选择浦东新区精神卫生中心早老性痴呆专科门诊患者54例,作超敏C反应蛋白、总抗氧化状态与血脂检测。[结果]与对照组比较,实验组hs-CRP、TAS差异非常显著,t1=4.55,t2=2.79,P1〈0.001,P2〈0.01;血脂中甘油三酯、低密度脂蛋白胆固醇、载脂蛋白B、Lp(a)差异显著;t1=3.01,P1〈0.01,t2=2.21,P2〈0.05,t3=2.64,P3〈0.01,t4=1.91,P4〈0.05。[结论]超敏C反应蛋白、总抗氧化状态联合血脂(甘油三酯、低密度脂蛋白胆固醇、载脂蛋白B、Lp(a))检测对实验室诊断早老性痴呆症具有较好敏感性和特异性,临床应用前景乐观。 相似文献
8.
MASAFUMI IKEDA SHIGETOSHI FUJIYAMA MOTOHIKO TANAKA MICHIO SATA TATSUYA IDE HIROSHI YATSUHASHI HIROSHI WATANABE 《Journal of gastroenterology and hepatology》2006,21(1):122-128
Background and Aim: This study investigated the clinical features of hepatocellular carcinoma in patients with sustained virological response to interferon for hepatitis C viral (HCV) infection. Methods: A total of 7715 patients with HCV infection were treated with interferon and followed up for more than 1 year after withdrawal of interferon in 64 Japanese hospitals and clinics between July 1988 and August 2001. Sustained virological response was obtained in 2515 (32.6%) patients. Of these 2515 patients, clinical data were collected for 38 patients in whom hepatocellular carcinoma developed. Sustained virological response was defined as HCV RNA negativity more than 6 months after the termination of interferon. Results: All patients were HCV RNA negative at the time of diagnosis of hepatocellular carcinoma. The median period until the detection of hepatocellular carcinoma was 4.7 years (range 1.4–9.0 years). There were significant improvements in hepatic function including serum albumin, aspartate aminotransferase, alanine aminotransferase, indocyanine green test, platelet count and histological activity grade in comparison with those before interferon therapy and at the onset of hepatocellular carcinoma. The maximum tumor size in patients without medical follow‐up for 1 year or more (median: 60 mm) was significantly larger than in patients who were periodically followed up for 6 months or less (median: 25 mm) (P = 0.002). Conclusions: The present findings emphasize the importance of regular medical follow up of patients with HCV infection, as even patients showing a sustained virological response to interferon and in whom hepatic function has improved have the potential to develop hepatocellular carcinoma. 相似文献
9.
本研究选择10μg/ml、20μg/ml、40μg/ml浓度的溴氰菊酯处理白纹伊蚊C6/36细胞,以MMC作为阳性对照物,观察溴氰菊酯处理24h后对C6/36细胞染色体畸变率和姐妹染色单体互换(SCE)频率的影响。结果显示,三个浓度的溴氰菊酯对C6/36细胞染色体畸变率均没有显著影响(P<0.05);溴氰菊酯浓度在40μg/ml时可诱导C6/36细胞SCE频率轻度增高(P>0.05),而溴氰菊酯浓度在10μg/ml、20μg/ml时,对C6/36细胞SCE频率没有诱导作用。表明溴氰菊酯对C6/36细胞的遗传学效应较弱 相似文献
10.