全文获取类型
收费全文 | 483224篇 |
免费 | 78154篇 |
国内免费 | 15015篇 |
专业分类
耳鼻咽喉 | 5331篇 |
儿科学 | 11019篇 |
妇产科学 | 7636篇 |
基础医学 | 67727篇 |
口腔科学 | 13401篇 |
临床医学 | 44568篇 |
内科学 | 70370篇 |
皮肤病学 | 9400篇 |
神经病学 | 28326篇 |
特种医学 | 16274篇 |
外国民族医学 | 346篇 |
外科学 | 57053篇 |
综合类 | 54903篇 |
现状与发展 | 85篇 |
一般理论 | 11篇 |
预防医学 | 23508篇 |
眼科学 | 5555篇 |
药学 | 36890篇 |
192篇 | |
中国医学 | 12353篇 |
肿瘤学 | 111445篇 |
出版年
2024年 | 1122篇 |
2023年 | 7025篇 |
2022年 | 13114篇 |
2021年 | 18961篇 |
2020年 | 21417篇 |
2019年 | 24761篇 |
2018年 | 23998篇 |
2017年 | 25850篇 |
2016年 | 26061篇 |
2015年 | 28233篇 |
2014年 | 36512篇 |
2013年 | 37812篇 |
2012年 | 32017篇 |
2011年 | 33425篇 |
2010年 | 26823篇 |
2009年 | 23586篇 |
2008年 | 24790篇 |
2007年 | 23115篇 |
2006年 | 20908篇 |
2005年 | 18584篇 |
2004年 | 16329篇 |
2003年 | 14073篇 |
2002年 | 12049篇 |
2001年 | 10356篇 |
2000年 | 8059篇 |
1999年 | 6207篇 |
1998年 | 5412篇 |
1997年 | 4905篇 |
1996年 | 4200篇 |
1995年 | 3731篇 |
1994年 | 3221篇 |
1993年 | 2623篇 |
1992年 | 2244篇 |
1991年 | 2031篇 |
1990年 | 1591篇 |
1989年 | 1460篇 |
1988年 | 1319篇 |
1987年 | 1095篇 |
1986年 | 957篇 |
1985年 | 1223篇 |
1984年 | 1061篇 |
1983年 | 746篇 |
1982年 | 764篇 |
1981年 | 659篇 |
1980年 | 564篇 |
1979年 | 411篇 |
1978年 | 284篇 |
1977年 | 226篇 |
1976年 | 178篇 |
1975年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
N. SUVAJD
I V. EMERIKI‐MARTINOVI . ARANOVI M. PETROVI M. POPOVI V. ARTIKO M. UPI I. ELEZOVI 《International journal of laboratory hematology》2006,28(5):317-320
We report the case of a littoral‐cell angioma of the spleen, a recently described benign vascular tumour, whose imaging and pathological characteristics have been discussed only by a few authors. The diagnosis was made after elective splenectomy. The CT images, scintigraphy and histological specimens are presented, and differential diagnoses discussed. 相似文献
33.
《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
34.
Nishard Abdeen Albert Cross Gregory Cron Steven White Thomas Rand David Miller Giles Santyr 《Magnetic resonance in medicine》2006,56(2):255-264
We used the dual capability of hyperpolarized 129Xe for spectroscopy and imaging to develop new measures of xenon diffusing capacity in the rat lung that (analogously to the diffusing capacity of carbon monoxide or DLCO) are calculated as a product of total lung volume and gas transfer rate constants divided by the pressure gradient. Under conditions of known constant pressure breath-hold, the volume is measured by hyperpolarized 129Xe MRI, and the transfer rate is measured by dynamic spectroscopy. The new quantities (xenon diffusing capacity in lung parenchyma (DLXeLP)), xenon diffusing capacity in RBCs (DLXeRBC), and total lung xenon diffusing capacity (DLXe)) were measured in six normal rats and six rats with lung inflammation induced by instillation of fungal spores of Stachybotrys chartarum. DLXeLP, DLXeRBC, and DLXe were 56 +/- 10 ml/min/mmHg, 64 +/- 35 ml/min/mmHg, and 29 +/- 9 ml/min/mmHg, respectively, for normal rats, and 27 +/- 9 ml/min/mmHg, 42 +/- 27 ml/min/mmHg, and 16 +/- 7 ml/min/mmHg, respectively, for diseased rats. Lung volumes and gas transfer times for LP (TtrLP) were 16 +/- 2 ml and 22 +/- 3 ms, respectively, for normal rats and 12 +/- 2 ml and 35 +/- 8 ms, respectively, for diseased rats. Xenon diffusing capacities may be useful for measuring changes in gas exchange associated with inflammation and other lung diseases. 相似文献
35.
A method is presented for 3D MRI in an extended field of view (FOV) based on continuous motion of the patient table and an efficient acquisition scheme. A gradient-echo MR pulse sequence is applied with lateral (left-right (L/R)) frequency-encoding direction and slab selection along the direction of motion. Compensation for the table motion is achieved by a combination of slab tracking and data alignment in hybrid space. The method allows fast k-space coverage to be achieved, especially when a short sampling FOV is chosen along the direction of table motion, as is desirable for good image quality. The method can be incorporated into different acquisitions schemes, including segmented k-space scanning, which allows for contrast variation with the use of magnetization preparation. Head-to-toe images of volunteers were obtained with good quality using 3D spoiled gradient-echo sequences. As an example of magnetization-prepared imaging, fat/water separated images were acquired using chemical shift selective (CHESS) presaturation pulses. 相似文献
36.
Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla. 总被引:2,自引:0,他引:2
Dirk Mayer Dong-Hyun Kim Elfar Adalsteinsson Daniel M Spielman 《Magnetic resonance in medicine》2006,55(5):974-978
A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner. 相似文献
37.
38.
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
39.
目的 探讨肺上沟癌的临床特点及放疗疗效和不良反应。方法 回顾性分析 3 3例肺上沟癌住院病人的临床特征和常规放疗的疗效。结果 肺上沟癌占原发性支气管肺癌的 2 9% ,常见症状为 :患侧肩、背和上肢疼痛 ( 78 8% ) ,后 1,2 ,3肋骨或椎骨破坏( 5 7 6% ) ,Horner’s综合征 ( 3 6 7% ) ;少见的症状为 :咳嗽 ( 2 7% ) ,咯血 ( 9% ) ;中位生存期为 8 4月 ;1,3 ,5年生存率分别为 3 5 6% ,12 3 % ,4 6% ;放疗反应可耐受。结论 肺上沟癌相当少见 ,其临床特征基本符合pancoast综合症 ,本病预后差 ,但放疗可缓解疼痛 ,提高生存质量。 相似文献
40.