全文获取类型
收费全文 | 69431篇 |
免费 | 5077篇 |
国内免费 | 2198篇 |
专业分类
耳鼻咽喉 | 517篇 |
儿科学 | 1358篇 |
妇产科学 | 2378篇 |
基础医学 | 7797篇 |
口腔科学 | 1277篇 |
临床医学 | 6075篇 |
内科学 | 7507篇 |
皮肤病学 | 913篇 |
神经病学 | 4933篇 |
特种医学 | 3636篇 |
外国民族医学 | 12篇 |
外科学 | 6061篇 |
综合类 | 10333篇 |
现状与发展 | 5篇 |
一般理论 | 6篇 |
预防医学 | 5479篇 |
眼科学 | 1841篇 |
药学 | 7924篇 |
76篇 | |
中国医学 | 5229篇 |
肿瘤学 | 3349篇 |
出版年
2024年 | 565篇 |
2023年 | 1046篇 |
2022年 | 1710篇 |
2021年 | 2408篇 |
2020年 | 2335篇 |
2019年 | 2277篇 |
2018年 | 2139篇 |
2017年 | 2170篇 |
2016年 | 2139篇 |
2015年 | 2088篇 |
2014年 | 3835篇 |
2013年 | 4786篇 |
2012年 | 3770篇 |
2011年 | 4196篇 |
2010年 | 3419篇 |
2009年 | 3180篇 |
2008年 | 3139篇 |
2007年 | 3140篇 |
2006年 | 2878篇 |
2005年 | 2634篇 |
2004年 | 2271篇 |
2003年 | 2194篇 |
2002年 | 1685篇 |
2001年 | 1598篇 |
2000年 | 1358篇 |
1999年 | 1292篇 |
1998年 | 1123篇 |
1997年 | 1108篇 |
1996年 | 992篇 |
1995年 | 966篇 |
1994年 | 818篇 |
1993年 | 684篇 |
1992年 | 612篇 |
1991年 | 531篇 |
1990年 | 554篇 |
1989年 | 475篇 |
1988年 | 346篇 |
1987年 | 302篇 |
1986年 | 353篇 |
1985年 | 491篇 |
1984年 | 459篇 |
1983年 | 282篇 |
1982年 | 362篇 |
1981年 | 301篇 |
1980年 | 318篇 |
1979年 | 237篇 |
1978年 | 196篇 |
1977年 | 192篇 |
1976年 | 172篇 |
1975年 | 132篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
992.
The antiviral agent foscarnet has long been used in our unit to treat cytomegalovirus (CMV) infections in renal transplant
patients. The clinical effect has been convincing and, apart from changes in serum calcium levels, very few side effects have
been noted. We have, however, observed a nephrotoxic reaction in a series of patients with initially good renal function who
therefore received high doses of foscarnet. Transplant biopsies performed in five of those patients revealed degenerative
changes in the tubular epithelial cells as well as tubular calcium deposits and an infiltration of the interstitium by mixed
mononuclear and polymorphonuclear leucocytes. Renal insufficiency was accompanied by high fever. After withdrawal of the drug,
the temperature rapidly normalized, whereas serum creatinine continued to rise for about 3 days and then fell back towards
previous levels. We conclude that transplant biopsies are of great value in distinguishing between a foscarnet nephrotoxic
effect and CMV nephritis, various forms of rejection, and other causes of impaired renal function. 相似文献
993.
G. M. Randleff-Rasmussen M. M. J. Oosthuizen J. A. Myburgh 《Transplant international》1989,2(4):181-186
Various methods of determining cyclosporin (CyA) levels in patients after kidney transplantation were compared. These included
polyclonal antibody (pcAb-), specific and nonspecific monoclonal antibody (S- and NmcAb-) radioimmunoassays (RIA), and high
performance liquid chromatography (HPLC). The results obtained by the various methods when compared showed some correlation
but did not correspond. A probable explanation for part of this noncorrespondence is the presence of monoclonally crossreactive
metabolites (CyA-M). Another reason was that the concentration of CyA in the standards supplied with the RIA kits was found
to be higher than stated. 相似文献
994.
Rebecca P. Hill Aaron Gardner Heather C. Crawford Rachel Richer Anna Dodds William A. Owens Clifford Lawrence Sam Rao Bo Kara S. Elizabeth James Colin A. Jahoda 《Experimental dermatology》2013,22(3):236-238
Traditional skin grafting techniques are effective but limited methods of skin replacement. Autologous transplantation of rapidly cultured keratinocytes is successful for epidermal regeneration, but the current gold‐standard technique requires mouse fibroblast feeders and serum‐rich media, with serum‐free systems and dermal fibroblast (DF) feeders performing relatively poorly. Here, we investigated the capacity of human hair follicle dermal cells to act as alternative supports for keratinocyte growth. Dermal papilla (DP) dermal sheath (DS), DF and 3T3 cells were used as inactivated feeder cells for human keratinocyte coculture. Under conditions favouring dermal cells, proliferation of keratinocytes in the presence of either DS or DP cells was significantly enhanced compared with DF cells, at levels comparable to keratinocytes cultured under gold‐standard conditions. Secreted protein acidic and rich in cysteine (SPARC) expression increased DS and DP cells relative to DFs; however, further experiments did not demonstrate a role in keratinocyte support. 相似文献
995.
M. Hynynen K. T. Olkkola E. Näveri R. Palojoki P. J. Neuvonen J. Heinonen 《Acta anaesthesiologica Scandinavica》1989,33(7):554-560
To evaluate possible factors affecting the pharmacokinetics of thiopentone during cardiopulmonary bypass (CPB), the present study was undertaken in patients scheduled for coronary artery bypass grafting and with in vitro experiments. The effects of nonpulsatile and pulsatile flow during CPB on the distribution and elimination of thiopentone were compared in 30 patients anaesthetized with fentanyl. The initial rapid phases of distribution of thiopentone were studied in 17 patients undergoing a nonpulsatile or pulsatile perfusion, to whom thiopentone 6 mg/kg was given as a rapid intravenous bolus during CPB. In order to study later distribution and early elimination of thiopentone, 13 patients perfused with a nonpulsatile or pulsatile flow received 6 mg/kg of the drug as a 15-min intravenous infusion before CPB. No differences in the pharmacokinetic parameters characterizing distribution and elimination of thiopentone were found between the patients undergoing nonpulsatile or pulsatile perfusion. As measured in 10 of the patients receiving the drug before the institution of CPB, no difference in plasma thiopentone level was observed in blood samples drawn simultaneously from a radial arterial cannula and a pulmonary artery catheter before, during and after CPB. This suggests that thiopentone is not sequestered in lungs during CPB. In vitro binding of thiopentone to the CPB equipment was studied in 6 experiments using a closed circuit. After a 60-min circulation time, only 50% of the predicted thiopentone level was recovered from the perfusate. It is concluded that replacing a nonpulsatile perfusion with a pulsatile one has no effect on the distribution and elimination of thiopentone in patients undergoing CPB. During CPB, thiopentone is sequestered in the extracorporeal circuit but not in the lungs. 相似文献
996.
目的探讨生活方式干预对长航人员长航中功能性胃肠病的影响及干预效果。方法采用整群抽样法使用罗马Ⅲ诊断标准制定的调查表对355名男性参加长航的海军官兵进行问卷调查。长航开始第一周采用问卷调查方式对研究对象进行生活方式评估,第二周制定个体化的生活方式干预方案,进行健康教育;第三周评价研究对象对方案的理解和实施情况,帮助研究对象建立良好的生活方式;第四周至第4个月底,对研究对象进行强化管理与督导。长航结束前一周,调查长航人员FGID的发病率和原有症状消失及缓解情况。结果干预后FGIDs总发病率由25.07%降至14.99%,任务结束后原发病人员症状消失、症状缓解率达49.44%。结论长期航海人员FGID发病比例较高。生活方式干预可减少FGID发病率,减轻症状,提高长航人员生活质量。 相似文献
997.
Methods for evaluation of retinal microvascular abnormalities associated with hypertension/sclerosis in the Atherosclerosis Risk in Communities Study 总被引:13,自引:0,他引:13
Hubbard LD Brothers RJ King WN Clegg LX Klein R Cooper LS Sharrett AR Davis MD Cai J 《Ophthalmology》1999,106(12):2269-2280
OBJECTIVE: To develop protocols to photograph and evaluate retinal vascular abnormalities in the Atherosclerosis Risk in Communities (ARIC) Study; to test reproducibility of the grading system; and to explore the relationship of these microvascular changes with blood pressure. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Among 4 examination centers, 11,114 participants (48-73 years of age) at their third triennial examination, after excluding persons with diabetes from this analysis. METHODS: One eye of each participant was photographed by technicians with nonmydriatic fundus cameras. Reading center graders evaluated focal arteriolar narrowing, arteriovenous (AV) nicking, and retinopathy by examining slides on a light box and measured diameters of all vessels in a zone surrounding the optic disc on enhanced digitized images. To gauge generalized narrowing, vessel diameters were combined into central arteriolar and venular equivalents with formulas adjusting for branching, and the ratio of equivalents (A/V ratio) was calculated. MAIN OUTCOME MEASURES: Retinal vascular abnormalities, mean arteriolar blood pressure (MABP). RESULTS: Among 11,114 participants, photographs were obtained of 99%, with quality sufficient to perform retinal evaluations in 81%. In the 9040 subjects with usable photographs, A/V ratio (lower values indicate generalized arteriolar narrowing) ranged from 0.57 to 1.22 (median = 0.84, interquartile range = 0.10), focal arteriolar narrowing was found in 7%, AV nicking in 6%, and retinopathy in 4%. Because of attrition of subjects and limitation of methods, prevalence of abnormality was likely underestimated. Controlling for gender, race, age, and smoking status, these retinal changes were associated with higher blood pressure. For every 10-mmHg increase in MABP, A/V ratio decreased by 0.02 unit (P < 0.0001), focal arteriolar narrowing had an odds ratio (OR) of 2.00 (95% confidence interval [CI] = 1.87-2.14), AV nicking had an OR of 1.25 (95% CI = 1.16-1.34), and retinopathy had an OR of 1.25 (95% CI = 1.15-1.37). For any degree of generalized narrowing, individuals with focal narrowing had MABP approximately 8 mmHg higher than those without (P < 0.0001). Masked replicate assessment of a sample found the following reproducibility: for A/V ratio, correlation coefficient = 0.79 and median absolute difference = 0.03; for focal arteriolar narrowing, kappa = 0.45; for AV nicking, kappa = 0.61; and for retinopathy, kappa = 0.89. CONCLUSION: Protocols have been developed for nonmydriatic fundus photography and for evaluation of retinal vascular abnormalities. Several microvascular changes were significantly associated with higher blood pressure; follow-up will show whether these are predictive of later cerebrovascular or cardiovascular disease independently of other known risk factors. 相似文献
998.
准分子激光原位角膜磨镶术矫正近视的初步研究 总被引:3,自引:1,他引:3
目的探讨准分子激光原位角膜磨镶术(LASIK)治疗低、中、高度近视的疗效。方法应用波长193nm的ArF准分子激光对147例(289眼)屈光度在-1.00D~-20.00D的近视及近视散光行LASIK治疗。结果对289眼随访6-10月,92%术后探视达到或超过术前最好矫正视力,10%的裸视达2.0,89.6%的术后屈光度在±1.00D之间,欠矫25眼,欠矫率仅为8.7%,术中术后无严重并发症。结论LASIK手术矫正近视及近视散光优于PRK手术,是一种更加准确、有效和安全的屈光手术方法。 相似文献
999.
目的 研究8-Br-cAMP对培养的人视网膜母细胞瘤HXO-Rb44细胞癌基因表达的效应及其与该细胞生长的关系。方法 c-fos mRNA,N-myc mRNA及p21ras mRNA均以原位杂交RNA斑点印迹技术检测,对繁殖细胞核抗原,v-Fos,N-Myc和P^21ras蛋白表达的免疫反应性则采用免疫组化及收白质斑点印迹技术检测。 相似文献
1000.
目的探讨曲美他嗪对大鼠心力衰竭模型心肌能量代谢的干预作用。方法腹主动脉缩窄法制备SD大鼠心力衰竭模型,心脏超声测定室间隔(IVS)及左心室后壁(LVPW)厚度、左心室舒张末期内径(LVD)和收缩末期内径(LVS)、左心室射血分数(LVEF)和短轴缩短率(FS);电镜观察心肌线粒体结构变化;放射免疫法检测CA-ATP、游离脂肪酸(FFA)。结果曲美他嗪治疗组和模型组比较,IVST、LVPWT、LVESD、LVEDD明显缩小,LVEF、FS升高;线粒体结构明显改善;CA-ATP水平升高,FFA水平降低。结论曲美他嗪能改善大鼠心力衰竭模型心肌能量代谢,改善心功能。 相似文献