首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   30976篇
  免费   3507篇
  国内免费   2096篇
耳鼻咽喉   266篇
儿科学   325篇
妇产科学   294篇
基础医学   3269篇
口腔科学   625篇
临床医学   4007篇
内科学   3924篇
皮肤病学   391篇
神经病学   1471篇
特种医学   1122篇
外国民族医学   16篇
外科学   2987篇
综合类   6270篇
现状与发展   8篇
一般理论   2篇
预防医学   2439篇
眼科学   610篇
药学   3459篇
  45篇
中国医学   2676篇
肿瘤学   2373篇
  2024年   196篇
  2023年   693篇
  2022年   1682篇
  2021年   2031篇
  2020年   1668篇
  2019年   1178篇
  2018年   1249篇
  2017年   1203篇
  2016年   1028篇
  2015年   1490篇
  2014年   1868篇
  2013年   1628篇
  2012年   2324篇
  2011年   2379篇
  2010年   1595篇
  2009年   1324篇
  2008年   1403篇
  2007年   1482篇
  2006年   1345篇
  2005年   1179篇
  2004年   1010篇
  2003年   1172篇
  2002年   1093篇
  2001年   894篇
  2000年   596篇
  1999年   551篇
  1998年   349篇
  1997年   363篇
  1996年   269篇
  1995年   236篇
  1994年   188篇
  1993年   108篇
  1992年   177篇
  1991年   141篇
  1990年   91篇
  1989年   84篇
  1988年   69篇
  1987年   78篇
  1986年   52篇
  1985年   36篇
  1984年   29篇
  1983年   14篇
  1982年   11篇
  1981年   8篇
  1980年   4篇
  1979年   11篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Frailty is associated with a pro-inflammatory state, which has been characterized by elevated levels of systemic inflammatory biomarkers, but has not been related to the number of co-existing chronic diseases associated with inflammation. We sought to determine the extent to which a higher number of inflammatory-related diseases is associated with frailty and to identify the most common disease patterns associated with being frail in older adults. We performed binomial regression analyses to assess whether a higher count of inflammatory-related diseases increases the probability of frailty using data from the WHAS I and II, companion cohorts composed of 70-79-year-old community-dwelling older women in Baltimore, Maryland (n = 620). An increase of one inflammatory-related disease was associated log-linearly with frailty (Prevalence Ratio (PR) = 2.28, 95% Confidence Interval (CI) = 1.81-2.87). After adjusting for age, race, education, and smoking status, the probability of frailty remained significant (PR = 1.97, 95%CI = 1.52-2.55). In the frail population, chronic kidney disease (CKD) and depressive symptoms (Prevalence = 22.9%, 95%CI = 14.2-34.8%); CVD and depressive symptoms (21.7%, 95%CI = 13.2-33.5%); CKD and anemia (18.7%, 95%CI = 11.1-29.7%); cardiovascular disease (CVD), CKD, and pulmonary disease (10.7%, 95%CI = 5.2-21.0%); CKD, anemia, and depressive symptoms (8.7%, 95%CI = 3.9-18.2%); and CVD, anemia, pulmonary disease, and depressive symptoms (5.0%, 95%CI = 1.6-14.4%) were among the most frequent disease combinations. Their prevalence percentages were significantly higher in the frail versus non-frail women. A higher inflammatory-related disease count, perhaps reflecting a greater pro-inflammatory burden, increases the likelihood of frailty. Shared mechanisms among specific disease combinations may further contribute to this risk.  相似文献   
992.
Left ventricular systolic dysfunction in patients with severe aortic stenosis (AS) is associated with poor outcome. This analysis was designed primarily to describe the clinical course of a large series of consecutive patients with severe AS and low ejection fraction (EF) (<40%) who, because of high surgical risk, were referred for transcatheter aortic valve implantation consideration. A cohort of 270 patients with severe AS and low EF (<40%) who were referred to participate in a clinical trial of transcatheter aortic valve implantation was studied. Clinical, hemodynamic, and periprocedural complications and follow-up mortality data were collected and compared between patients with low mean transvalvular gradients (≤40 mm Hg, n = 170 [63%]) and high transvalvular gradients (>40 mm Hg, n = 100 [37%]). Patients with low gradients were younger (mean age 79.8 ± 9.1 vs 83.8 ± 7.7 years, p <0.001) and had higher incidences of coronary artery disease and renal failure. Mean aortic valve area was larger (0.73 ± 0.23 vs 0.53 ± 0.18 cm(2), p <0.001), while mean EF (26.4 ± 6.9% vs 30.5% ± 6.6%, p <0.001), cardiac output (3.7 ± 1.1 vs 4.1 ± 1.3 L/min, p = 0.04), and cardiac index (1.9 ± 0.5 vs 2.1 ± 0.6 L/min/m(2), p = 0.04) were lower in patients with lower gradients compared to those with higher gradients, respectively. Mortality was higher in patients with low gradients (53.8%) at a mean follow-up of 151 days compared to those with high gradients (41%) at a mean follow-up of 256 days (p = 0.01). In conclusion, patients with severe AS and low EF with low transvalvular gradients are at higher risk for worse outcomes compared to patients with high transvalvular gradients. Surgery or transcatheter aortic valve implantation treatment and high baseline transvalvular gradient are associated with EF improvement.  相似文献   
993.
Data from randomized clinical trials have shown the safety and efficacy of the XIENCE V in selected populations. However, limited data are available comparing the XIENCE V to the first-generation CYPHER sirolimus-eluting stent. This study aimed to assess the long-term safety and clinical efficacy of the XIENCE V everolimus-eluting stent compared to first-generation stents in an unselected patient population. This retrospective analysis included 6,069 patients treated with CYPHER, TAXUS, and XIENCE stents from 2003 to 2009 at our institution. The patients were followed up for ≥1 year after the index procedure. The baseline characteristics were generally comparable among the 3 groups, with the exception of a significantly greater prevalence of diabetes mellitus, systemic hypertension, and a history of angioplasty and coronary bypass surgery among the XIENCE patients. The XIENCE patients also had a twofold greater rate of type C lesions. One-year follow-up data were available for 82% of the patients. The 1-year major adverse cardiovascular events rate was 9.3% for the XIENCE stent versus 9.8% for the CYPHER stent and 11.5% for the TAXUS stent (p = 0.11). Mortality was lower in the XIENCE group than in the CYPHER and TAXUS groups (3.6% vs 4.9% vs 7.2%, respectively, p <0.001), and target lesion revascularization was similar (5.9% vs 5.2% vs 5.6%, respectively; p = 0.34). Stent thrombosis was lower in the XIENCE patients (0.2% vs 1.2% vs 0.7%, p = 0.007). In conclusion, in a contemporary United States clinical practice with an unselected patient population, use of the XIENCE V stent was associated with an improved safety profile and reduction of all-cause mortality and stent thrombosis compared to first-generation drug-eluting stents. The XIENCE V failed to demonstrate superiority for overall major adverse cardiovascular events, Q-wave myocardial infarction, and revascularization rates.  相似文献   
994.
IntroductionThe objective is to investigate the influence of ghrelin administration on both the insulin secretion and the expression of ATP-sensitive K+ channels in islet.MethodsGhrelin and [D-Lys3] growth hormone releasing peptide-6 were administered via intraperitoneal injection in Wistar rats at the doses 10 and 10 μmol/kg/d for 2 weeks, respectively. Then glucose tolerance tests were performed and plasma insulin concentrations were measured. Islets were isolated for insulin release experiments. Single β cells were isolated for electrophysiological experiments. Determination of the Kir6.2 and SUR1 mRNA and protein expression levels in islets was performed by polymerase chain reaction and western blotting.ResultsIntraperitoneal administration of exogenous ghrelin significantly (P < 0.05) increased blood glucose concentrations, attenuated insulin responses during glucose tolerance tests, reduced insulin release from the isolated islets induced by 11.1 and 16.7 mmol/L glucose, hyperpolarized the resting membrane potential and increased the Kir6.2 mRNA and protein expression levels. In contrast, counteraction of ghrelin by intraperitoneal injection of [D-Lys3] growth hormone releasing peptide-6 significantly (P < 0.05) attenuated the aforementioned changes. SUR1 expression levels were not altered in this study.ConclusionsGhrelin via pancreatic growth hormone secretagogue receptor up-regulates the Kir6.2 expression in islet by hyperpolarizing the resting membrane potential which results in the inhibition of insulin release.  相似文献   
995.
目的比较不同抛光方法对烤瓷表面粗糙度的影响,以及不同粗糙度烤瓷表面对口腔变异链球菌黏附的影响。方法采用原子力显微镜测量不同抛光方法对瓷表面粗糙度的影响,并通过细菌实验观察不同粗糙度的瓷表面对细菌黏附的影响。结果用抛光膏抛光或者上釉后,瓷面平整且有光泽。无论是表面粗糙度还是表面黏附的细菌数,橡皮轮组都大于抛光膏组和上釉组(P<0.05)。结论建议调改过的瓷表面进行抛光膏抛光或上釉以恢复瓷表面的光滑度和减少口腔致龋菌的黏附。  相似文献   
996.
25例(30侧)下颌骨髁突囊内矢状骨折患者,均采用小"S"形深部拉钩辅助下复位,用侧壁拉力螺钉行坚固内固定,全部治愈。应用小"S"形深部拉钩可缩短手术时间,复位效果好,可有效避免深部组织损伤,值得推广。  相似文献   
997.
The objective of this study was to measure the related parameters of intercarotid artery (ICA) in the operative plane of endonasal transsphenoidal approach for hypophyseal surgeries. Nine parameters of the ICA were examined in the computed tomographic angiographic (CTA) scan of 101 patients. The shortest distance between the middle point of the nasal columella and the projective point of the ICA (D(3)) was 85.50 (5.79) mm. The shortest distance between the anterior wall of the sphenoid sinus and the projective point of the ICA (D(4)) was 16.93 (3.50) mm. The distance between the bilateral projective points of the ICA (D(5)) was 21.60 (3.45) mm. The shortest distance from the anterior wall of the sphenoid sinus to the line between the bilateral projective points of the ICA (D(6)) was 12.1 (3.91) mm. The shortest distance between the middle point of nasal columella and the anterior wall of the sphenoid sinus (D(7)) was 72.67 (5.99) mm. The width of the angle between the bilateral ICA projective point from the middle point of the nasal columella (A(1)) was 14.9 (2.32) degrees. The width of the angle between the bilateral ICA projective points from the anterior-most point of sphenoid sinus (A(2)) was 85.49 (18.12) degrees. Clinically, it is relatively safe to work within the distances and angles measured in this research, and these results may provide information for clinical surgery of pituitary tumor.  相似文献   
998.
ObjectiveTo evaluate the facial morphology characteristics of patients with complete unilateral cleft lip and palate (UCCLPs) who had undergone cleft palate repair at different times.DesignThis study included 46 nonsyndromic UCCLPs and 38 age and sex matched non-cleft patients. 35 cephalometric measurements were used to evaluate the facial morphology. Student’s t-test, one-way ANOVA and rank sum tests were used for comparison. Significant difference was defined at 95% level.ResultsThe data showed that UCCLPs who had palatoplasty between 7 and 12 years had greater PMP-A, PMP-ANS, Ba-ANS, Ba-A, Ba-N-ANS than those operated on before 4 years of age, and UCCLPs who had palatoplasty at 4–12 years had smaller Y-axis angle than those operated on before 4 years of age.ConclusionsThe maxillary sagittal length increased gradually as von Langenbeck repair was delayed. UCCLPs who underwent palate repair using von Langenbeck technique at 4–12 years had a more protrusive maxilla and less clockwise rotated mandible than those repaired before 4 years. UCCLPs operated using the von Langenbeck technique at 4–12 years had better head-face morphology than those operated on before 4 years. There was no difference in facial morphology among UCCLPs with palate repair at 4–12 years.  相似文献   
999.
口腔上皮不仅作为外界环境与宿主之间的一道物理屏障,还具有分泌多种抗菌肽参与天然免疫的作用。其中β-防御素家族具有广谱抗菌的作用,对口腔内的多种细菌有抑制作用,从而保护宿主的健康。本文就β-防御素在牙龈组织的表达及其与牙周可疑致病菌的相互作用关系作一综述。  相似文献   
1000.
目的:探讨双源CT(Dual-source computed tomography,DSCT)在颌面部肿瘤诊疗中的应用价值。方法:7例颌面部肿瘤病人通过双源CT检查,将数据发送至工作站进行多平面重建、容积重建。结果,7例患者均经手术治疗,术中所见肿瘤部位与周围神经、血管、软组织及硬组织关系均与双源CT检查结果一致。结论:双源CT具有扫描速度快,图像清晰的特点,在工作站上三维影像可以任意旋转和切割,从不同角度观察肿瘤与周边血管、神经、软组织及硬组织的关系,为诊断和治疗提供了大量准确信息。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号