全文获取类型
收费全文 | 51401篇 |
免费 | 3122篇 |
国内免费 | 345篇 |
专业分类
耳鼻咽喉 | 697篇 |
儿科学 | 1100篇 |
妇产科学 | 902篇 |
基础医学 | 6667篇 |
口腔科学 | 1871篇 |
临床医学 | 4336篇 |
内科学 | 12630篇 |
皮肤病学 | 911篇 |
神经病学 | 5571篇 |
特种医学 | 2338篇 |
外科学 | 7796篇 |
综合类 | 238篇 |
一般理论 | 10篇 |
预防医学 | 2331篇 |
眼科学 | 844篇 |
药学 | 2713篇 |
中国医学 | 134篇 |
肿瘤学 | 3779篇 |
出版年
2023年 | 473篇 |
2022年 | 743篇 |
2021年 | 1709篇 |
2020年 | 1046篇 |
2019年 | 1460篇 |
2018年 | 1677篇 |
2017年 | 1384篇 |
2016年 | 1578篇 |
2015年 | 1655篇 |
2014年 | 2182篇 |
2013年 | 2652篇 |
2012年 | 4183篇 |
2011年 | 4123篇 |
2010年 | 2349篇 |
2009年 | 2111篇 |
2008年 | 3374篇 |
2007年 | 3461篇 |
2006年 | 3173篇 |
2005年 | 2998篇 |
2004年 | 2622篇 |
2003年 | 2416篇 |
2002年 | 2149篇 |
2001年 | 446篇 |
2000年 | 391篇 |
1999年 | 442篇 |
1998年 | 445篇 |
1997年 | 339篇 |
1996年 | 297篇 |
1995年 | 241篇 |
1994年 | 225篇 |
1993年 | 177篇 |
1992年 | 187篇 |
1991年 | 157篇 |
1990年 | 133篇 |
1989年 | 95篇 |
1988年 | 131篇 |
1987年 | 108篇 |
1986年 | 85篇 |
1985年 | 108篇 |
1984年 | 83篇 |
1983年 | 72篇 |
1982年 | 79篇 |
1981年 | 58篇 |
1980年 | 63篇 |
1979年 | 70篇 |
1978年 | 53篇 |
1977年 | 54篇 |
1974年 | 40篇 |
1973年 | 53篇 |
1972年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Trawat Attarbaschi Julia Sacher Thomas Geiss-Granadia Nikolas Klein Nilufar Mossaheb Rupert Lanzenberger Susanne Asenbaum Robert Dudczak Siegfried Kasper Johannes Tauscher 《European neuropsychopharmacology》2007,17(2):102-107
We explored the relationship between striatal dopamine-2 (D(2)) receptor occupancy and extra-pyramidal symptoms (EPS) in bipolar patients receiving olanzapine. Seventeen patients with a DSM-IV diagnosis of bipolar disorder were treated with 5-45 mg/day olanzapine for at least 14 days. After that period, D(2) receptor occupancy was determined using Iodobenzamide (IBZM) and SPECT. EPS were assessed by the Simpson-Angus Scale (SAS) and Barnes-Akathisia Scale (BAS). We found a dose-dependent increase in occupancy: 5 mg led to 28-50%, 10 mg to 40-68%, 15 mg to 69%, 20 mg to 57-66%, 30 mg to 66% and 45 mg to 80% D(2) receptor occupancy; and a significant correlation between plasma levels and occupancy (R(2)=.55, P=.001). Similar to schizophrenic patients, bipolar patients did not exhibit EPS at D(2) occupancy levels of 28 to 80%. Although we did not find an increased vulnerability for acute EPS in bipolar patients receiving olanzapine at clinical relevant doses, this needs to be replicated with larger sample sizes. 相似文献
42.
Ohne ZusammenfassungMit 2 Textabbildungen. 相似文献
43.
Johannes Seitz 《Virchows Archiv : an international journal of pathology》1871,52(1-2):114-123
Ohne Zusammenfassung 相似文献
44.
Johannes Woitzik Elke Lassel Ulf C. Schneider Helmut Schroeck Rudolf Graf 《Experimental neurology》2009,218(1):41-350
Lesion evolution during focal cerebral ischemia may depend on flow restrictions or on accumulation of toxic mediators within the infarct and expansion of these factors to the periinfarct region. So far, the precise contribution of flow dependent versus spreading-mediated impairment of viable periinfarct tissue has not been determined. Therefore, we measured lesion expansion, flow restrictions and glutamate distribution on serial brain sections at different time points after experimental focal ischemia.Permanent focal ischemia was induced by occlusion of the right middle cerebral artery in male rats and the flow reduction was subsequently measured at 1, 12 and 24 h using iodo[14C]antipyrine autoradiography. Additionally, the necrotic volume was determined on serial brain sections and the glutamate content was measured in tissue samples from adjacent microdissections.Twelve hours after focal ischemia no noteworthy viable areas with blood flow restrictions of 20-40 ml 100 g− 1 min− 1 existed but at 24 h the necrotic tissue exceeded the hemodynamically compromised region by 40 ± 21 mm3 (24%). Furthermore, at 12 and 24 h the glutamate content was elevated in areas surrounding the infarct.Relevant flow restrictions are detectable only during early stages of infarct maturation, whereas the propagation of secondary factors may be the predominant mechanism for delayed infarct evolution. 相似文献
45.
Rupert R Lanzenberger Markus Mitterhauser Christoph Spindelegger Wolfgang Wadsak Nikolas Klein Leonhard-Key Mien Alexander Holik Trawat Attarbaschi Nilufar Mossaheb Julia Sacher Thomas Geiss-Granadia Kurt Kletter Siegfried Kasper Johannes Tauscher 《Neuropsychopharmacology》2007,61(9):1081-1089
BACKGROUND: Results from studies in serotonin-1A (5-HT1A) knockout mice and previous positron emission tomography (PET) studies in humans imply a role for 5-HT1A receptors in normal state anxiety as well as in certain anxiety disorders. The objective of this study was to investigate 5-HT1A receptor binding potential (BP) in social anxiety disorder (SAD). METHODS: Using PET and [carbonyl-11C]WAY-100635, we compared a homogeneous group of 12 unmedicated, male SAD patients with 18 healthy control subjects (HC). A multivariate ANOVA with all regional BP values as dependent variables, age and four radiochemical variables as covariates was performed. RESULTS: We found a significantly lower 5-HT1A BP in several limbic and paralimbic areas but not in the hippocampus (p = .234) of SAD patients. The difference in 5-HT1A binding was most significant in the amygdala (-21.4%; p = .003). There was also a more than 20% lower 5-HT(1A) BP of SAD patients in the anterior cingulate cortex (p = .004), insula (p = .003), and dorsal raphe nuclei (p = .030). CONCLUSIONS: The lower 5-HT1A binding in the amygdala and mesiofrontal areas of SAD patients is consistent with 1) preclinical findings of elevated anxiety in 5-HT1A knockout mice, 2) a previous PET study in healthy volunteers showing an inverse correlation between 5-HT1A BP and state anxiety, and 3) another human PET study in patients with panic disorder showing reduced 5-HT1A binding, thus corroborating the potential validity of 5-HT1A receptors as targets in the treatment of human anxiety disorders. 相似文献
46.
We conducted a double blind controlled trial in 28 Duchenne muscular dystrophy (DMD) patients with Deflazacort (DF), an oxazoline derivative of prednisolone which reduces its side-effects. Myometric muscle strength measurements, Scott Score and timed tests showed statistically significant improvement for the treated group (P less than 0.05). Side-effects after 9 months of treatment included mild cushingoid appearance in four patients (28%) and moderate in only one (7%), increased appetite in seven (50%), increased body hair in four (28%), irritability and hyperactivity in three (21%). Increased body weight was not prominent and was controlled with dietary measures. No patient had to be withdrawn from medication. More research and long-term follow-up are needed in order to establish the mechanism of improvement and the consequences of long-term steroid administration in DMD. In this regard DF appears as an alternative to prednisone preserving its benefits but with fewer side-effects. 相似文献
47.
Kerstin Schmidt Johannes Hoffend Annette Altmann Ludwig G Strauss Antonia Dimitrakopoulou-Strauss Britta Engelhardt Dirk Koczan J?rg Peter Thomas J Dengler Walter Mier Michael Eisenhut Uwe Haberkorn Ralf Kinscherf 《Journal of nuclear medicine》2006,47(3):543-551
Growth of malignant tumors is dependent on sufficient blood supply. Thus, inhibition of tumor angiogenesis is emerging as a promising target in the treatment of malignancies. Human angiostatin (hANG) is one of the most potent inhibitors of endothelial cell proliferation, angiogenesis, and tumor growth in vivo. However, its mechanisms operating in vivo are not well understood. METHODS: To obtain more information about functional changes in the angiogenic process, we established Morris hepatoma (MH3924A) cell lines expressing hANG (hANG-MH3924A). The effects of hANG expression on proliferation and apoptosis of human umbilical vein endothelial cells (HUVECs) were measured in coculture experiments in vitro. To evaluate changes in tumor perfusion and blood volume, H2 15O and 68Ga-DOTA-albumin (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N',N'-tetraacetic acid) were used for PET studies in vivo. Additionally, immunohistologic quantification of vascularization, apoptosis, and proliferation as well as gene array analyses were performed. RESULTS: Our in vitro experiments demonstrate reduced proliferation and increased apoptosis in HUVECs when being cocultured with hANG-MH3924A. In support, tumor growth of hANG-MH3924A is diminished by 95% in vivo. However, tumor perfusion and blood volume are increased in hANG-MH3924A corresponding to an increased microvessel density. Furthermore, hANG-transfected tumors show changes in expression of genes related to apoptosis, stress, signal transduction, and metabolism. CONCLUSION: hANG expression leads to inhibition of tumor growth, increased apoptosis, and changes in the expression of multiple genes involved in stress reactions, signal transduction, and apoptosis, which indicates a multifactorial reaction of tumors. An enhanced microvessel density is seen as part of these reactions and is associated with increased perfusion as measured by PET. 相似文献
48.
49.
Carlos Alberto Herrero de Morais Norberti Bernardineli Roberto B Garcia Marco A H Duarte Danilo M Z Guerisoli 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2006,102(3):417-421
OBJECTIVE: The aim of this study was to evaluate the biocompatibility of Portland cement with the addition of iodoform, compared to MTA (ProRoot). STUDY DESIGN: Eighteen Wistar albino rats were divided into 3 groups of 6 animals each. Polyethylene tubes were filled either with freshly mixed MTA or Portland cement mixed with iodoform (20% wt/wt) and implanted subcutaneously. An empty tube served as control. After 7, 30, or 60 days, the implants together with the surrounding tissues were removed in blocks. Sections were evaluated for the presence and thickness of a fibrous capsule, presence of granulation tissue, and the severity of inflammatory response. Data were submitted to nonparametric statistical analysis with individual comparisons between groups at a significance level of P < 0.05. RESULTS: There were no differences between inflammatory responses at 7 and 30 days. After 60 days from surgical removal, there was significantly more tissue reaction to the MTA and Portland cement compared to the control group. CONCLUSION: There were no significant differences regarding inflammatory responses between MTA and Portland cement with iodoform after 7, 30, or 60 days. After 60 days, the fibrous capsule around the Portland cement appeared more organized than tissue surrounding MTA implants. After 60 days, there was still a significantly increased tissue reaction to the 2 cements compared to the empty polyethylene tubes. 相似文献
50.
Dozent Dr. Gerhard Eigler Dozent Dr. Johannes Koch 《European archives of oto-rhino-laryngology》1938,144(1-2):156-162
Ohne Zusammenfassung 相似文献