全文获取类型
收费全文 | 3540篇 |
免费 | 195篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 133篇 |
妇产科学 | 31篇 |
基础医学 | 344篇 |
口腔科学 | 66篇 |
临床医学 | 247篇 |
内科学 | 877篇 |
皮肤病学 | 97篇 |
神经病学 | 463篇 |
特种医学 | 112篇 |
外科学 | 700篇 |
综合类 | 12篇 |
预防医学 | 177篇 |
眼科学 | 22篇 |
药学 | 199篇 |
中国医学 | 3篇 |
肿瘤学 | 248篇 |
出版年
2023年 | 25篇 |
2022年 | 67篇 |
2021年 | 113篇 |
2020年 | 50篇 |
2019年 | 68篇 |
2018年 | 108篇 |
2017年 | 62篇 |
2016年 | 89篇 |
2015年 | 116篇 |
2014年 | 131篇 |
2013年 | 199篇 |
2012年 | 246篇 |
2011年 | 233篇 |
2010年 | 161篇 |
2009年 | 140篇 |
2008年 | 203篇 |
2007年 | 227篇 |
2006年 | 239篇 |
2005年 | 215篇 |
2004年 | 172篇 |
2003年 | 129篇 |
2002年 | 157篇 |
2001年 | 54篇 |
2000年 | 62篇 |
1999年 | 57篇 |
1998年 | 37篇 |
1997年 | 24篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1994年 | 16篇 |
1993年 | 5篇 |
1992年 | 47篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 28篇 |
1988年 | 11篇 |
1987年 | 20篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 20篇 |
1982年 | 10篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1976年 | 18篇 |
1975年 | 9篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1970年 | 6篇 |
1967年 | 6篇 |
排序方式: 共有3772条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
Carmelo Tassi Antonio Angelini Tommaso Beccari Enrico Capodicasa 《Clinical chemistry and laboratory medicine》2006,44(7):843-847
BACKGROUND: The activity and isoenzyme composition of N-acetyl-beta-D-hexosaminidase (EC.3.2.1.52) in seminal plasma of fertile and infertile men have been evaluated. However, no data are available on the isoenzyme content in seminal plasma from patients with secretory azoospermia. METHODS: The activity and isoenzyme composition of seminal plasma from 15 normozoospermic controls and 18 patients with secretory azoospermia were determined by fluorimetric methods. 4-Methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside and 4-methylumbelliferil-2-acetamido-2-deoxy-beta-D-glucopyranoside-6-sulfate were used as fluorigenic substrates. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic efficiency of the assays. RESULTS: No significant difference was found in total enzyme activity between the two groups, while isoenzyme A activity was significantly lower (p=0.004) and the ratio between total enzyme activity and isoenzyme A activity was significantly higher (p=0.04) in azoospermic patients compared to controls. The diagnostic efficiency of these evaluations was low (< or =75.7%). CONCLUSIONS: Our findings show that the isoenzyme composition of N-acetyl-beta-D-hexosaminidase in seminal plasma from patients with secretory azoospermia is significantly different from controls, but this difference does not represent a useful marker of secretory azoospermia. The fluorimetric assays are simple and rapid methods for evaluating the isoenzyme composition. 相似文献
6.
Williamson Kathleen A.; Hever Ann M.; Rainger Joe; Rogers R. Curtis; Magee Alex; Fiedler Zdenek; Keng Wee Teik; Sharkey Freddie H.; McGill Niolette; Hill Clare J.; Schneider Adele; Messina Mario; Turnpenny Peter D.; Fantes Judy A.; van Heyningen Veronica; FitzPatrick David R. 《Human molecular genetics》2006,15(12):2030
Table 1 相似文献
7.
Microvascular involvement represents one of the first apparent steps in many autoimmune diseases such as rheumatoid arthritis (RA). Early in the disease, peripheral microangiopathy may be easily recognized and studied by videocapillaroscopy. The aim of this study has been to observe the differences in labial microcirculation between healthy patients and patients suffering from RA. A total of 30 healthy patients and 30 patients suffering from RA were examined. The patients with conditions known to compromise microcirculation, such as diabetes, hypertension, or some pharmacological treatments were not included in the study. All the patients were non-smokers. Labial capillaroscopy was used to investigate the characteristics of microcirculation. Visibility, course, tortuosity, as well as the possible presence of microhemorrhages, the average caliber of the capillary loops and the number of visible capillary loops per square millimeter were evaluated for each patient. The investigation was simple, non-invasive, and repeatable for each patient. In patients suffering from RA, it was possible to observe a reduced caliber of capillaries, as well as greater elongated capillaries, in comparison to controls. This study shows that capillary alterations in patients suffering from RA occur in labial mucosa microcirculation; such evidence could be extremely important in the diagnosis of suspected RA. 相似文献
8.
J Emerg Nurs 1998;24:622. 相似文献
9.
Mono- and bi-allelic expression of insulin-like growth factor II gene in human muscle tumors 总被引:4,自引:1,他引:3
Pedone Paolo V.; Tirabosco Roberto; Cavazzana Andrea O.; Ungaro Paola; Basso Giuseppe; Luksch Roberto; Carli Modesto; Bruni Carmelo B.; Frunzio Rodolfo; Riccio Andrea 《Human molecular genetics》1994,3(7):1117-1121
Insulin-like growth factor II (IGF-II) is a mitogen for manycell types and an important modulator of muscle growth and differentiation.IGF-II gene is prevalently expressed during prenatal developmentand its gene activity is regulated by genomic imprinting, inthat the allele inherited from the father is active and theallele inherited from the mother is inactive in most normaltissues. IGF-II expression is activated in several types ofhuman neoplasms and an alteration of IGF-II imprinting has beendescribed in BeckwithWiedemann syndrome and Wilms' tumour.Here we show that monoallelic expression of IGF-II gene is conservedin normal adult muscle tissue whereas two or more copies ofactive IGF-II alleles, arising by either relaxation of imprintingor duplication of the active allele, are found in 9 out of 11(82%) rhabdomyo-sarcomas retaining heterozygosity at 11p15,regardless of the histological subtype. Since IGF-II has beenindicated as an autocrine growth factor for rhabdomyosarcomacells, these findings strongly suggest that acquisition of adouble dosage of active IGF-II gene is an important step forthe initiation or progression of rhabdomyosarcoma tumorigenesis.Among different types of muscle tumors, relaxation of imprintingseems to arise prevalently in rhabdomyosarcomas, since we havedetected only one case of partial reactivation of the maternalIGF-II allele out of 7 lelomyosarcomas tested. 相似文献
10.
Gianmauro Sacchetti Eugenio Inglese Angelo S Bongo Franco Aina Marco Brambilla Alberto Baroli Carmelo Cernigliaro Pierfranco Dellavesa Edgardo Pittaluga Marco Rudoni 《European journal of nuclear medicine and molecular imaging》1997,24(10):1230-1236
The aim of this study was to determine the diagnostic accuracy of technetium-99m tetrofosmin myocardial imaging for the localization
of coronary artery stenoses of different degrees of severity. Stress-rest single-photon emission tomography (SPET) was performed
on separate days in 80 patients (64 males, 16 females; mean age 61 years; 43 patients with previous myocardial infarction;
18 patients with pharmacological stress), within 6 months of coronary angiography. Scintigraphic images were blindly and independently
evaluated by three observers. Coronary stenosis was defined as a >50% narrowing in luminal diameter; severe stenosis was defined
as a proximal stenosis of >75% or a peripheral stenosis of >90%. Coronary angiography revealed normal coronary arteries or
insignificant coronary stenosis in 13 patients and significant coronary stenoses in 67 patients. The sensitivity and specificity
of 99mTc-tetrofosmin SPET in respect of severely stenosed vessels were, respectively, 80% and 65% for the left anterior descending
artery (LAD), 100% and 46% for the right coronary artery (RCA) and 58 and 78% for the left circumflex artery (LCx) territories.
Considering all the significantly stenosed vessels, a significant decrease in sensitivity was observed for LAD territories
(to 59%, P=0.05), and a nonsignificant decrease for RCA (88%) and LCx (47%) territories while specificity values remained essentially
unchanged. No significant changes in sensitivity or specificity were observed when regions with previous myocardial infarction
were excluded. In conclusion, the sensitivity of 99mTc-tetrofosmin SPET for the localization of individual stenosed vessels is only moderate when all significant stenoses are
considered, but the ability of this technique to predict the location of severe coronary artery stenoses seems satisfactory,
with the exception of the low specificity in respect of RCA territories.
Received 26 April and in revised form 7 June 1997 相似文献