全文获取类型
收费全文 | 4418篇 |
免费 | 402篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 198篇 |
妇产科学 | 150篇 |
基础医学 | 542篇 |
口腔科学 | 64篇 |
临床医学 | 520篇 |
内科学 | 1297篇 |
皮肤病学 | 31篇 |
神经病学 | 216篇 |
特种医学 | 259篇 |
外国民族医学 | 1篇 |
外科学 | 841篇 |
综合类 | 53篇 |
一般理论 | 2篇 |
预防医学 | 232篇 |
眼科学 | 55篇 |
药学 | 127篇 |
中国医学 | 1篇 |
肿瘤学 | 229篇 |
出版年
2019年 | 52篇 |
2018年 | 52篇 |
2017年 | 62篇 |
2016年 | 51篇 |
2015年 | 54篇 |
2014年 | 90篇 |
2013年 | 126篇 |
2012年 | 117篇 |
2011年 | 140篇 |
2010年 | 87篇 |
2009年 | 78篇 |
2008年 | 126篇 |
2007年 | 158篇 |
2006年 | 150篇 |
2005年 | 171篇 |
2004年 | 125篇 |
2003年 | 110篇 |
2002年 | 104篇 |
2001年 | 118篇 |
2000年 | 108篇 |
1999年 | 104篇 |
1998年 | 72篇 |
1997年 | 64篇 |
1996年 | 56篇 |
1995年 | 55篇 |
1994年 | 82篇 |
1993年 | 51篇 |
1992年 | 87篇 |
1991年 | 87篇 |
1990年 | 96篇 |
1989年 | 124篇 |
1988年 | 121篇 |
1987年 | 100篇 |
1986年 | 119篇 |
1985年 | 111篇 |
1984年 | 84篇 |
1983年 | 88篇 |
1982年 | 51篇 |
1981年 | 49篇 |
1980年 | 46篇 |
1979年 | 66篇 |
1978年 | 68篇 |
1977年 | 51篇 |
1976年 | 58篇 |
1975年 | 70篇 |
1974年 | 78篇 |
1973年 | 67篇 |
1972年 | 62篇 |
1970年 | 46篇 |
1967年 | 48篇 |
排序方式: 共有4866条查询结果,搜索用时 15 毫秒
51.
The most common manifestation of HIV/AIDS in the kidney is the collapsing variant of focal segmental glomerular sclerosis, HIV-associated nephropathy (HIVAN). Other forms of renal disease in HIV-infected patients include mesangial proliferative glomerulonephritis (GN), membranoproliferative GN, IgA nephropathy, minimal change disease and proliferative immune-complex GN. We present the case of a 42-year-old Caucasian male with HIV infection, treatment associated peripheral neuropathy, nephrotic syndrome and progressive renal failure. The initial and subsequent kidney biopsies showed diffuse proliferative glomerulonephritis resembling diffuse proliferative (WHO class IV) lupus nephritis. There was no clinical or serological evidence of systemic lupus erythematosus (SLE). Proteinuria improved with ACE-inhibitors, and renal function remained relatively stable while receiving highly active antiretroviral therapy (HAART). A precipitous decline in renal function to end-stage renal disease followed a brief period of withdrawal from potent antiretroviral therapy during which the viral load rebounded. Considering previously reported cases, it appears that lupus-like nephritis is a rare but well-defined pattern of immune-complex-induced renal injury seen in HIV-infected patients. It appears to be markedly responsive to HAART. 相似文献
52.
Ruel MA Sellke FW Bianchi C Khan TA Faro R Zhang JP Cohn WE 《The Annals of thoracic surgery》2003,75(5):1443-1449
BACKGROUND: The gastrointestinal submucosa physiologically produces angiogenic proteins. We examined whether these properties could lead to endogenous myocardial angiogenesis in a swine model of chronic ischemia. METHODS: Fifteen Yorkshire swine underwent ameroid constrictor placement around the circumflex artery and either lateral epicardial abrasion, creation of a gastroepiploic artery (GEA) based gastric patch, mucosal avulsion, transdiaphragmatic transfer, and apposition of the patch against the circumflex myocardial territory (number = 8; test animals), or lateral epicardial abrasion alone (number = 7; controls). Seven weeks later, lateral myocardial perfusion, endothelial cell density, and expression of VEGFR-1 and VE-cadherin were determined using isotope-labeled microsphere assays, immunohistochemistry, and immunoblotting, respectively. RESULTS: Microsphere assays showed equivalent lateral/anterior myocardial perfusion indices at rest (1.10 +/- 0.49 vs 0.95 +/- 0.23, test vs control animals; p = 0.54), but higher perfusion in test animals versus controls during pacing (1.05 +/- 0.29 vs 0.69 +/- 0.09, test vs controls; p = 0.02). Increased myocardial endothelial cell density (42.6 +/- 8.5 vs 26.1 +/- 11.6 cells per 3850 microm2, test vs controls; p = 0.02) and expression of VE-cadherin (3.10 +/- 0.60-fold change, test vs controls; p = 0.001) were also observed in the lateral territory of test animals versus controls. Reconstitution of the proximally occluded circumflex artery from patch collaterals was demonstrated on gastroepiploic arteriography in a subset of test animals. CONCLUSIONS: This model results in an angiogenic process of significantly greater magnitude than that resulting from chronic myocardial ischemia alone, without the need for exogenous angiogenic agents. 相似文献
53.
Schulman CI Cohn SM Blackbourne L Soffer D Hoskins N Bowers N Habib F Crookes B Benjamin B Pizano LR 《The Journal of trauma》2005,59(1):92-95
OBJECTIVE: The purpose of this study was to determine the optimal time interval for identifying a pneumothorax (PTX) on chest radiograph (CXR) after placing a chest tube on water seal. METHODS: One hundred nineteen chest tubes were placed on water seal according to a prospective, observational study protocol. After water seal, both an early (3.1 +/- 2.1 hours) and a late (17.6 +/- 8.0 hours) CXR was obtained. RESULTS: Thirty-one patients had a PTX on follow-up CXRs. There were 22 early and 9 late PTXs identified. Three patients in the early group had a clinically significant PTX or an increase in the size of PTX on follow-up CXR. None of the patients in the late group had a clinically significant PTX (any worsening of their PTX) or required further intervention. CONCLUSION: A normal chest radiograph obtained 3 hours after placing a chest tube on water seal effectively excludes development of a clinically significant pneumothorax. 相似文献
54.
Daniels DL; Czervionke LF; Millen SJ; Haberkamp TJ; Meyer GA; Hendrix LE; Mark LP; Williams AL; Haughton VM 《Radiology》1989,171(3):807-809
The authors evaluated magnetic resonance (MR) images obtained with intravenously administered gadolinium in ten patients who had facial paralysis and no facial nerve tumor. In patients with either Bell palsy (four patients) or facial paralysis after temporal bone surgery (six patients), intratemporal facial nerve enhancement was seen. Facial nerve enhancement on MR images proved to be a nonspecific finding. 相似文献
55.
Computed tomographic study of hormone-secreting microadenomas 总被引:1,自引:0,他引:1
Hemminghytt S; Kalkhoff RK; Daniels DL; Williams AL; Grogan JP; Haughton VM 《Radiology》1983,146(1):65
56.
石杉碱甲类似物的研究II.N-甲基吡啶酮石杉碱甲类似物的合成 总被引:3,自引:1,他引:3
石杉碱甲(1)是从中草药石杉属植物千层塔(Lycopodium serratum Thunb.)中分得的一种高效可逆的乙酰胆碱酯酶抑制剂,临床试验证实它对早老性痴呆症有显著疗效。本文报道N-甲基吡啶酮石杉碱甲类似物2和3的合成。2-甲氧基-5-甲氧羰基-11-亚甲基-5,9-甲撑环辛-7-烯并吡啶(9)在乙腈中用三甲基氯硅烷和碘化钠选择性脱保护以定量的产率得吡啶酮10,再用甲醇钠和碘甲烷甲基化得N-甲基吡啶酮11,11经碱性水解,Curtius重排和氨基的脱保护得N-甲基吡啶酮石杉碱甲类似物2。通过类似的途径从中间体2-甲氧基-5-甲氧羰基-7-甲基-11-酮-5,9-甲撑环辛-7-烯并吡啶(14)合成了类似物3。类似物2和3的乙酰胆碱酯酶抑制活性均低于天然石杉碱甲。 相似文献
57.
58.
Race and the response to adrenergic blockade with carvedilol in patients with chronic heart failure 总被引:9,自引:0,他引:9
Yancy CW Fowler MB Colucci WS Gilbert EM Bristow MR Cohn JN Lukas MA Young ST Packer M;U.S. Carvedilol Heart Failure Study Group 《The New England journal of medicine》2001,344(18):1358-1365
BACKGROUND: The benefits of angiotensin-converting-enzyme inhibitors and beta-blockers may be smaller in black patients than in patients of other races, but it is unknown whether race influences the response to carvedilol in patients with chronic heart failure. METHODS: In the U.S. Carvedilol Heart Failure Trials Program, 217 black and 877 nonblack patients (in New York Heart Association class II, III, or IV and with a left ventricular ejection fraction of no more than 0.35) were randomly assigned to receive placebo or carvedilol (at doses of 6.25 to 50 mg twice daily) for up to 15 months. The effects of carvedilol on ejection fraction, clinical status, and major clinical events were retrospectively compared between black and nonblack patients. RESULTS: As compared with placebo, carvedilol lowered the risk of death from any cause or hospitalization for any reason by 48 percent in black patients and by 30 percent in nonblack patients. Carvedilol reduced the risk of worsening heart failure (heart failure leading to death, hospitalization, or a sustained increase in medication) by 54 percent in black patients and by 51 percent in nonblack patients. The ratios of the relative risks associated with carvedilol for these two outcome variables in black as compared with nonblack patients were 0.74 (95 percent confidence interval, 0.42 to 1.34) and 0.94 (95 percent confidence interval, 0.43 to 2.05), respectively. Carvedilol also improved functional class, ejection fraction, and the patients' and physicians' global assessments in both the black patients and the nonblack patients. For all these measures of outcome and clinical status, carvedilol was superior to placebo within each racial cohort (P<0.05 in all analyses), and there was no significant interaction between race and treatment (P> 0.05 in all analyses). CONCLUSIONS: The benefit of carvedilol was apparent and of similar magnitude in both black and nonblack patients with heart failure. 相似文献
59.
Wynne Callon Somnath Saha P. Todd Korthuis Ira B. Wilson Richard D. Moore Jonathan Cohn Mary Catherine Beach 《AIDS and behavior》2016,20(5):1108-1115
This study evaluated how clinicians assess antiretroviral (ARV) adherence in clinical encounters, and which questions elicit accurate responses. We conducted conversation analysis of audio-recorded encounters between 34 providers and 58 patients reporting ARV non-adherence in post-encounter interviews. Among 42 visits where adherence status was unknown by providers, 4 providers did not discuss ARVs (10 %), 6 discussed ARVs but did not elicit non-adherence disclosure (14 %), and 32 discussed ARVs which prompted disclosure (76 %). Questions were classified as: (1) clarification of medication (“Are you still taking the Combivir?”); (2) broad (“How’s it going with your meds?”); (3) positively-framed (“Are you taking your medications regularly?”); (4) negatively-framed (“Have you missed any doses?”). Clinicians asked 75 ARV-related questions: 23 clarification, 12 broad, 17 positively-framed, and 23 negatively-framed. Negatively-framed questions were 3.8 times more likely to elicit accurate disclosure than all other question types (p < 0.0001). Providers can improve disclosure probability by asking directly about missed doses. 相似文献
60.
Frazier OH Tuzun E Cohn WE Conger JL Kadipasaoglu KA 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2006,52(2):145-149
Continuous-flow pumps are small, simple, and respond physiologically to input variations, making them potentially ideal for total heart replacement. However, the physiological effects of complete pulseless flow during long-term circulatory support without a cardiac interface or with complete cardiac exclusion have not been well studied. We evaluated the feasibility of dual continuous-flow pumps as a total artificial heart (TAH) in a chronic bovine model. Both ventricles of a 6-month-old Corriente crossbred calf were excised and sewing rings attached to the reinforced atrioventricular junctions. The inlet portions of 2 Jarvik 2000 pumps were positioned through their respective sewing rings at the mid-atrial level and the pulseless atrial reservoir connected end-to-end to the pulmonary artery and aorta. Pulseless systemic and pulmonary circulations were thereby achieved. Volume status was controlled, and systemic and pulmonary resistance were managed pharmacologically to keep mean arterial pressures at 100+/-10 mmHg (systemic) and 20+/-5 mmHg (pulmonary) and both left and right atrial pressures at 15+/-5 mmHg. The left pump speed was maintained at 14,000 rpm and its output autoregulated in response to variations in right pump flow, systemic and pulmonary pressures, fluid status, and activity level. Hemodynamics, end-organ function, and neurohormonal status remained normal. These results suggest the feasibility of using dual continuous-flow pumps as a TAH. 相似文献