全文获取类型
收费全文 | 59901篇 |
免费 | 4443篇 |
国内免费 | 266篇 |
专业分类
耳鼻咽喉 | 637篇 |
儿科学 | 2101篇 |
妇产科学 | 1563篇 |
基础医学 | 8915篇 |
口腔科学 | 973篇 |
临床医学 | 5751篇 |
内科学 | 13287篇 |
皮肤病学 | 1370篇 |
神经病学 | 6346篇 |
特种医学 | 1302篇 |
外科学 | 5087篇 |
综合类 | 364篇 |
现状与发展 | 1篇 |
一般理论 | 45篇 |
预防医学 | 5929篇 |
眼科学 | 1016篇 |
药学 | 4555篇 |
中国医学 | 146篇 |
肿瘤学 | 5222篇 |
出版年
2023年 | 639篇 |
2022年 | 1433篇 |
2021年 | 2513篇 |
2020年 | 1468篇 |
2019年 | 1909篇 |
2018年 | 2088篇 |
2017年 | 1699篇 |
2016年 | 1880篇 |
2015年 | 2038篇 |
2014年 | 2632篇 |
2013年 | 3304篇 |
2012年 | 4898篇 |
2011年 | 4840篇 |
2010年 | 2602篇 |
2009年 | 2233篇 |
2008年 | 3743篇 |
2007年 | 3762篇 |
2006年 | 3438篇 |
2005年 | 3149篇 |
2004年 | 2896篇 |
2003年 | 2602篇 |
2002年 | 2350篇 |
2001年 | 455篇 |
2000年 | 414篇 |
1999年 | 455篇 |
1998年 | 424篇 |
1997年 | 363篇 |
1996年 | 247篇 |
1995年 | 249篇 |
1994年 | 245篇 |
1993年 | 197篇 |
1992年 | 226篇 |
1991年 | 243篇 |
1990年 | 220篇 |
1989年 | 215篇 |
1988年 | 222篇 |
1987年 | 178篇 |
1986年 | 156篇 |
1985年 | 165篇 |
1984年 | 182篇 |
1983年 | 129篇 |
1982年 | 126篇 |
1981年 | 118篇 |
1980年 | 93篇 |
1979年 | 103篇 |
1978年 | 81篇 |
1977年 | 80篇 |
1976年 | 72篇 |
1975年 | 74篇 |
1974年 | 73篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Reduced bleeding events with subcutaneous administration of recombinant human factor IX in immune-tolerant hemophilia B dogs
下载免费PDF全文
![点击此处可从《Blood》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Russell KE Olsen EH Raymer RA Merricks EP Bellinger DA Read MS Rup BJ Keith JC McCarthy KP Schaub RG Nichols TC 《Blood》2003,102(13):4393-4398
Intravenous administration of recombinant human factor IX (rhFIX) acutely corrects the coagulopathy in hemophilia B dogs. To date, 20 of 20 dogs developed inhibitory antibodies to the xenoprotein, making it impossible to determine if new human FIX products, formulations, or methods of chronic administration can reduce bleeding frequency. Our goal was to determine whether hemophilia B dogs rendered tolerant to rhFIX would have reduced bleeding episodes while on sustained prophylactic rhFIX administered subcutaneously. Reproducible methods were developed for inducing tolerance to rhFIX in this strain of hemophilia B dogs, resulting in a significant reduction in the development of inhibitors relative to historical controls (5 of 12 versus 20 or 20, P <.001). The 7 of 12 tolerized hemophilia B dogs exhibited shortened whole blood clotting times (WBCTs), sustained detectable FIX antigen, undetectable Bethesda inhibitors, transient or no detectable antihuman FIX antibody titers by enzyme-linked immunosorbent assay (ELISA), and normal clearance of infused rhFIX. Tolerized hemophilia B dogs had 69% reduction in bleeding frequency in year 1 compared with nontolerized hemophilia B dogs (P =.0007). If proven safe in human clinical trials, subcutaneous rhFIX may provide an alternate approach to prophylactic therapy in selected patients with hemophilia B. 相似文献
992.
The prevalence of gastroesophageal reflux disease (GERD) increases with age and elderly are more likely to develop severe disease. Older patients often complain of less severe or frequent heartburn than younger patients and they may present with atypical symptoms such as dysphagia, weight loss, or extraesophageal symptoms. Proton pump inhibitors (PPIs) are central in the management of GERD and are unchallenged with regards to their efficacy. They are considered safe and more effective than histamine receptor antagonists for healing esophagitis and for preventing its recurrence using a long term maintenance treatment. PPI have minimal side effects and few slight drug interactions and are considered safe for long term treatment. Pantoprazole is significantly effective both for acute and long-term treatment with excellent control of relapse and symptoms. It is well tolerated even for long-term therapy and its tolerability is optimal. Pantoprazole shows to have minimal interactions with other drugs because of a lower affinity for cytocrome P450 than older PPIs. Although the majority of elderly has concomitant illnesses and receive other drugs, this does not adversely effect the efficacy of pantoprazole because of its pharmacokinetics, which are independent of patient age. Clinical practice suggests that a low dose maintenance of PPIs should be used in older patients with GERD. 相似文献
993.
994.
Daniel R Kao G Taganov K Greger JG Favorova O Merkel G Yen TJ Katz RA Skalka AM 《Proceedings of the National Academy of Sciences of the United States of America》2003,100(8):4778-4783
Caffeine is an efficient inhibitor of cellular DNA repair, likely through its effects on ATM (ataxia telangiectasia mutated) and ATR (ATM and Rad3-related) kinases. Here, we show that caffeine treatment causes a dose-dependent reduction in the total amount of HIV-1 and avian sarcoma virus retroviral vector DNA that is joined to host DNA in the population of infected cells and also in the number of transduced cells. These changes were observed at caffeine concentrations that had little or no effect on overall cell growth, synthesis, and nuclear import of the viral DNA, or the activities of the viral integrase in vitro. Substantial reductions in the amount of host-viral-joined DNA in the infected population, and in the number of transductants, were also observed in the presence of a dominant-negative form of the ATR protein, ATRkd. After infection, a significant fraction of these cells undergoes cell death. In contrast, retroviral transduction is not impeded in ATM-deficient cells, and addition of caffeine leads to the same reduction that was observed in ATM-proficient cells. These results suggest that activity of the ATR kinase, but not the ATM kinase, is required for successful completion of the viral DNA integration process and/or survival of transduced cells. Components of the cellular DNA damage repair response may represent potential targets for antiretroviral drug development. 相似文献
995.
Rissanen TT Korpisalo P Markkanen JE Liimatainen T Ordén MR Kholová I de Goede A Heikura T Gröhn OH Ylä-Herttuala S 《Circulation》2005,112(25):3937-3946
996.
Regula J Hennig E Burzykowski T Orlowska J Przytulski K Polkowski M Dziurkowska-Marek A Marek T Nowak A Butruk E Ostrowski J 《Digestion》2003,67(1-2):25-31
BACKGROUND: Although Helicobacter pylori is a significant etiologic factor of peptic ulcer disease, it remains unknown why ulcers develop only in the minority of infected individuals. AIM: The aim of this cross-sectional study was to evaluate the association between the presence of duodenal ulcer in H. pylori-infected patients and different risk factors. METHODS: A total of 122 H. pylori-infected patients were enrolled; 79 had duodenal ulcer and 43 gastritis. Univariate analysis was conducted using either Fisher's exact test or exact Cochrane-Armitage trend test. In multivariate analysis the logistic model was used. RESULTS: Univariate analysis indicated six factors (male sex, smoking, antral H. pylori density, CAGA presence in antrum, and VACA s1a presence in antrum and corpus). Four factors (sex, smoking-alcohol index, H. pylori density index, and CAGA index) were found to be significant in multivariate analysis. The best model predicting duodenal ulcer included male sex, smoking, presence of H. PYLORI on histopathology in antrum and CAGA presence in corpus. CONCLUSION: Although several risk factors were significantly associated with duodenal ulcer, we failed in the identification of either a single risk factor or a set of factors that can unequivocally differentiate patients with ulcer from those with gastritis. 相似文献
997.
998.
Angelone T Quintieri AM Brar BK Limchaiyawat PT Tota B Mahata SK Cerra MC 《Endocrinology》2008,149(10):4780-4793
Circulating levels of catestatin (Cts; human chromogranin A352-372) decrease in the plasma of patients with essential hypertension. Genetic ablation of the chromogranin A (Chga) gene in mice increases blood pressure and pretreatment of Chga-null mice with Cts prevents blood pressure elevation, indicating a direct role of Cts in preventing hypertension. This notable vasoreactivity prompted us to test the direct cardiovascular effects and mechanisms of action of wild-type (WT) Cts and naturally occurring human variants (G364S-Cts and P370L-Cts) on myocardial and coronary functions. The direct cardiovascular actions of WT-Cts and human variants were determined using the Langendorff-perfused rat heart. WT-Cts dose-dependently increased heart rate and coronary pressure and decreased left ventricular pressure, rate pressure product and both positive and negative LVdP/dt. WT-Cts not only inhibited phospholamban phosphorylation, but also the inotropic and lusitropic effects of WT-Cts were abolished by chemical inhibition of beta2-adrenergic receptors, Gi/o protein, nitric oxide or cGMP, indicating involvement of beta2-adrenergic receptors-Gi/o protein-nitric oxide-cGMP signaling mechanisms. In contrast, G364S-Cts did not affect basal cardiac performance but abolished isoproterenol-induced positive inotropism and lusitropism. P370L-Cts decreased rate pressure product and inhibited only isoproterenol-induced positive inotropism and lusitropism by 70%. Cts also inhibited endothelin-1-induced positive inotropism and coronary constriction. Taken together, the cardioinhibitory influence exerted on basal mechanical performance and the counterregulatory action against beta-adrenergic and endothelin-1 stimulations point to Cts as a novel cardiac modulator, able to protect the heart against excessive sympathochromaffin overactivation, e.g. hypertensive cardiomyopathy. 相似文献
999.
Comparison of dobutamine stress echocardiography with and without real-time perfusion imaging for detection of coronary artery disease 总被引:2,自引:0,他引:2
Xie F Tsutsui JM McGrain AC Demaria A Cotter B Becher H Lebleu C Labovitz A Picard MH O'Leary EL Porter TR 《The American journal of cardiology》2005,96(4):506-511
In a pilot study of 27 patients, those who presented with chest pain underwent 2 dobutamine stress echocardiographic studies, 1 with high mechanical index harmonic imaging to analyze wall motion without contrast and 1 with real-time low mechanical index perfusion imaging with intravenous Optison to assess myocardial perfusion and wall motion. All patients then underwent quantitative coronary angiography. Two independent reviewers demonstrated an improvement in sensitivity when analyzing myocardial perfusion. In the 21 patients who had significant coronary stenoses, 14 had abnormal myocardial perfusion detected at peak stress and 7 had abnormal wall motion detected by standard dobutamine stress echocardiography. There was decreased specificity with perfusion imaging by 1 reviewer. The addition of real-time perfusion imaging after intravenous contrast during dobutamine stress echocardiography has the potential to improve detection of coronary artery disease. 相似文献
1000.