全文获取类型
收费全文 | 1764篇 |
免费 | 136篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 28篇 |
妇产科学 | 16篇 |
基础医学 | 301篇 |
口腔科学 | 51篇 |
临床医学 | 137篇 |
内科学 | 333篇 |
皮肤病学 | 40篇 |
神经病学 | 226篇 |
特种医学 | 64篇 |
外科学 | 274篇 |
综合类 | 7篇 |
预防医学 | 146篇 |
眼科学 | 29篇 |
药学 | 102篇 |
肿瘤学 | 137篇 |
出版年
2023年 | 14篇 |
2022年 | 20篇 |
2021年 | 44篇 |
2020年 | 32篇 |
2019年 | 50篇 |
2018年 | 40篇 |
2017年 | 38篇 |
2016年 | 37篇 |
2015年 | 44篇 |
2014年 | 49篇 |
2013年 | 76篇 |
2012年 | 86篇 |
2011年 | 83篇 |
2010年 | 54篇 |
2009年 | 58篇 |
2008年 | 95篇 |
2007年 | 103篇 |
2006年 | 95篇 |
2005年 | 91篇 |
2004年 | 76篇 |
2003年 | 71篇 |
2002年 | 74篇 |
2001年 | 43篇 |
2000年 | 31篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 24篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 20篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 18篇 |
1987年 | 19篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 16篇 |
1981年 | 20篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 15篇 |
1976年 | 11篇 |
1975年 | 13篇 |
1973年 | 12篇 |
1967年 | 14篇 |
排序方式: 共有1904条查询结果,搜索用时 109 毫秒
1.
2.
Klaus Edvardsen Nils Brünner Mogens Spang-Thomsen Frank S. Walsh Elisabeth Bock 《International journal of developmental neuroscience》1993,11(5)
A cDNA encoding a transmembrane 140 kDa isoform of the neural cell adhesion molecule, NCAM, was transfected into the rat glioma cell line BT4Cn. Transfectants with a homogeneously high expression of NCAM-B showed a decreased capacity for penetration of an artificial basement membrane when compared to cells transfected with expression-vector alone or untransfected cells. However, when injected subcutaneously into nude mice, both NCAM expressing cells and control cells produced invasive tumors. Nude mice injected with NCAM positive cells developed tumors with slower growth rates as compared to those induced by NCAM negative cells. This implies that NCAM may not only be involved in adhesive and motile behaviour of glioma cells, but also in their growth regulation. 相似文献
3.
Thomas B?llingtoft Knudsen Simon Francis Thomsen Charlotte Suppli Ulrik Mogens Fenger Steen Nepper-Christensen Vibeke Backer 《The Journal of asthma》2007,44(4):257-260
BACKGROUND: Season of birth (SOB) has been regarded as a risk factor for atopy. The aim of this study was to explore the relationship between season of birth (SOB) and later development of atopic disease in children and adolescents. METHODS: A total of 1,007 randomly selected subjects, 7 to 17 years of age, who were living in urban Copenhagen, Denmark were studied. All participants were interviewed about respiratory symptoms and possible risk factors for atopic disease. Skin test reactivity, serum total immunoglobulin E (IgE), and airway responsiveness were measured using standard techniques. RESULTS: The overall risk of atopy, as judged by skin test reactivity and serum total IgE, was the same regardless of SOB. On the contrary, asthma was more common in subjects born in the autumn compared with subjects born during the remaining part of the year (12.4% vs. 5.6%), OR = 2.40, 95% CI (1.56-3.94), p < 0.001. This was observed both for atopic asthma OR = 2.41, 95% CI (1.25-4.64), p = 0.007, non-atopic asthma, OR = 2.35, 95% CI (1.14-4.83), p = 0.02, and house dust mite (HDM) sensitive airway hyperresponsiveness, OR = 3.00, 95% CI (1.44-6.24), p = 0.002. Rhinitis and pollen allergy were not significantly related to SOB. CONCLUSIONS: Atopy itself is independent of season of birth, whereas asthma is more prevalent among subjects born during the autumn. Regarding asthma, these results suggest that the first months of life enclose a period of particular vulnerability towards environmental risk factors, especially exposure to aeroallergens like HDM. 相似文献
4.
Dose-response comparisons of five lung surfactant factor (LSF) preparations in an animal model of adult respiratory distress syndrome (ARDS). 总被引:1,自引:1,他引:0 下载免费PDF全文
D. Hfner R. Beume U. Kilian G. Krasznai B. Lachmann 《British journal of pharmacology》1995,115(3):451-458
1. We have examined the effects of five different lung surfactant factor (LSF) preparations in the rat lung lavage model. In this model repetitive lung lavage leads to lung injury with some similarities to adult respiratory distress syndrome with poor gas exchange and protein leakage into the alveolar spaces. These pathological sequelae can be reversed by LSF instillation soon after lavage. 2. The tested LSF preparations were: two bovine: Survanta and Alveofact: two synthetic: Exosurf and a protein-free phospholipid based LSF (PL-LSF) and one Recombinant LSF at doses of 25, 50 and 100 mg kg-1 body weight and an untreated control group. 3. Tracheotomized rats (10-12 per dose) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min-1, inspiration expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH2O at positive end-expiratory pressure (PEEP) of 8 cmH2O. Two hours after LSF administration, PEEP and in parallel PIP was reduced from 8 to 6 (1st reduction), from 6 to 3 (2nd reduction) and from 3 to 0 cmH2O (3rd reduction). 4. Partial arterial oxygen pressure (PaO2, mmHg) at 5 min and 120 min after LSF administration and during the 2nd PEEP reduction (PaO2(PEEP23/3)) were used for statistical comparison. All LSF preparations caused a dose-dependent increase for the PaO2(120'), whereas during the 2nd PEEP reduction only bovine and recombinant LSF exhibited dose-dependency. Exosurf did not increase PaO2 after administration of the highest dose. At the highest dose Exosurf exerted no further improvement but rather a tendency to relapse.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
Dr. Flemming Moesgaard M.D. Mogens Lykkegaard Nielsen M.D. Ph.D. Allan Hjortrup M.D. Peter Kjersgaard M.D. Carsten Sørensen M.D. Peter Nørgaard Larsen M.D. Steen Hoffmann M.D. 《Diseases of the colon and rectum》1989,32(1):36-38
One hundred ninety patients with peritonitis at the time of abdominal surgery were allocated at random to systemic antibiotic
treatment alone or systemic antibiotic treatment combined with topical application of antibiotics in the wound at the time
of wound closure. The overall wound infection rate was 17 percent without significant difference between the two treatment
groups (P>0.80). 相似文献
6.
7.
8.
During the time from 1982/83 the intracranial pressure was continuously measured from patients who were polytraumatized and also had severe head injuries. In 53% of these cases the first readings could be obtained within 6 hours after the injury and in 33% first after 12 hours. During the time of evaluation this relationship shifted to earlier implantation. From 27% of these patients the intracranial pressure values fell into a range that instigated immediate therapeutical measures. This proves how important it is to have a direct reading from the intracranial pressure as soon as possible after injury. The aspects of therapy by increased intracranial pressure were discussed. 相似文献
9.
10.
Motoaki Nakamura Dean F Salisbury Yoshio Hirayasu Sylvain Bouix Kilian M Pohl Takeshi Yoshida Min-Seong Koo Martha E Shenton Robert W McCarley 《Neuropsychopharmacology》2007,62(7):773-783
BACKGROUND: Overall neocortical gray matter (NCGM) volume has not been studied in first-episode schizophrenia (FESZ) at first hospitalization or longitudinally to evaluate progression, nor has it been compared with first-episode affective psychosis (FEAFF). METHODS: Expectation-maximization/atlas-based magnetic resonance imaging (MRI) tissue segmentation into gray matter, white matter (WM), or cerebrospinal fluid (CSF) at first hospitalization of 29 FESZ and 34 FEAFF, plus 36 matched healthy control subjects (HC), and, longitudinally approximately 1.5 years later, of 17 FESZ, 21 FEAFF, and 26 HC was done. Manual editing separated NCGM and its lobar parcellation, cerebral WM (CWM), lateral ventricles (LV), and sulcal CSF (SCSF). RESULTS: At first hospitalization, FESZ and FEAFF showed smaller NCGM volumes and larger SCSF and LV than HC. Longitudinally, FESZ showed NCGM volume reduction (-1.7%), localized to frontal (-2.4%) and temporal (-2.6%) regions, and enlargement of SCSF (7.2%) and LV (10.4%). Poorer outcome was associated with these LV and NCGM changes. FEAFF showed longitudinal NCGM volume increases (3.6%) associated with lithium or valproate administration but without clinical correlations and regional localization. CONCLUSIONS: Longitudinal NCGM volume reduction and CSF component enlargement in FESZ are compatible with post-onset progression. Longitudinal NCGM volume increase in FEAFF may reflect neurotrophic effects of mood stabilizers. 相似文献