全文获取类型
收费全文 | 100587篇 |
免费 | 9879篇 |
国内免费 | 6290篇 |
专业分类
耳鼻咽喉 | 965篇 |
儿科学 | 1570篇 |
妇产科学 | 1084篇 |
基础医学 | 10825篇 |
口腔科学 | 1888篇 |
临床医学 | 13231篇 |
内科学 | 14379篇 |
皮肤病学 | 1697篇 |
神经病学 | 4238篇 |
特种医学 | 4068篇 |
外国民族医学 | 43篇 |
外科学 | 9257篇 |
综合类 | 17983篇 |
现状与发展 | 26篇 |
一般理论 | 8篇 |
预防医学 | 8284篇 |
眼科学 | 2256篇 |
药学 | 11158篇 |
109篇 | |
中国医学 | 6260篇 |
肿瘤学 | 7427篇 |
出版年
2024年 | 349篇 |
2023年 | 1483篇 |
2022年 | 3753篇 |
2021年 | 5028篇 |
2020年 | 3829篇 |
2019年 | 3079篇 |
2018年 | 3233篇 |
2017年 | 3211篇 |
2016年 | 3034篇 |
2015年 | 4847篇 |
2014年 | 6100篇 |
2013年 | 6039篇 |
2012年 | 8764篇 |
2011年 | 9162篇 |
2010年 | 6534篇 |
2009年 | 5412篇 |
2008年 | 6293篇 |
2007年 | 5974篇 |
2006年 | 5740篇 |
2005年 | 5157篇 |
2004年 | 3474篇 |
2003年 | 3029篇 |
2002年 | 2625篇 |
2001年 | 1827篇 |
2000年 | 1568篇 |
1999年 | 1391篇 |
1998年 | 873篇 |
1997年 | 869篇 |
1996年 | 656篇 |
1995年 | 607篇 |
1994年 | 509篇 |
1993年 | 291篇 |
1992年 | 374篇 |
1991年 | 304篇 |
1990年 | 246篇 |
1989年 | 200篇 |
1988年 | 208篇 |
1987年 | 144篇 |
1986年 | 128篇 |
1985年 | 92篇 |
1984年 | 63篇 |
1983年 | 45篇 |
1982年 | 36篇 |
1981年 | 31篇 |
1980年 | 18篇 |
1979年 | 28篇 |
1978年 | 10篇 |
1974年 | 8篇 |
1972年 | 9篇 |
1971年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 24 毫秒
991.
采用新近发展的cDNA代表性差异分析法筛选鼻咽癌中不表达的或表达降低的cDNA序列。结果显示:有9个与已知基因高度同源的cDNA序列。通过对这些已知基因的结构和功能分析,发现有与细胞骨架成分相关的基因:αactinin,ezrin和细胞角蛋白13;直接与瘤基因和抑瘤基因相互作用的基因:鲨烯合成酶和TRIP1基因;直接参与DNA合成以及调控基因转录和翻译的基因:TAFⅡ68和组蛋白H10;另外还有人类补体因子B及类转运RNA合成酶的基因。这些基因大多具有相当于抑瘤基因的功能。从而进一步说明鼻咽癌的发生是多基因相互作用的结果。 相似文献
992.
用伊曲康唑短程间歇冲击疗法治疗甲真菌病54例(指甲真菌病26例,趾甲真菌病28例),并随访9个月。结果显示:患者指甲临床治愈率为885%,真菌学治愈率为961%;趾甲临床治愈率为821%,真菌学治愈率为961%;仅有74%的患者出现恶心、胃肠道不适等轻微副作用。本疗法疗效高、副作用小和安全性好 相似文献
993.
目的:比较长期实验性应激源对老龄、青龄糖尿病倾向鼠血糖和胰岛素分泌的不同影响并探讨其机制。方法:取1-5 月龄( 青龄) 和15 月龄( 老龄) 昆明小鼠各40 只,用链脲佐菌素诱导糖尿病倾向后(STZ 鼠) ,各分为应激组与对照组。两组应激STZ 鼠均给予6 周实验性应激源刺激( 限制、旋转、拥挤) ,检测其空腹血糖(FBG) 、空腹血浆胰岛素(FINS) 、胰腺组织脂质过氧化物(LPO) 和一氧化氮代谢产物(NO-2 ,NO-3 ) 水平,观察胰腺组织超氧化物歧化酶(SOD) 活性的变化,并对STZ 鼠胰岛炎的严重程度进行评分。结果:经长期实验性应激的老龄STZ 鼠FBG 水平增高较青龄者显著,且FINS 水平明显下降;胰岛炎恶化较青龄STZ鼠严重;胰腺组织LPO 和NO-2 ,NO-3 含量增高及SOD 活性降低均较青龄STZ鼠明显;上述各指标间存在相关性。结论:长期实验性应激促使老龄STZ 鼠血糖增高、胰岛炎加重和胰岛素分泌机能耗竭的效应较青龄STZ 鼠明显;胰腺NO 过量及过氧化损伤可能参与这一差异的产生机制 相似文献
994.
目的建立用斑点免疫金渗滤试验(DIGFA)检测血请中登革病毒抗原的方法。方法一株DV4型特异性单克隆抗体点加于硝酸纤维膜上,以捕获血清中的DV4抗原。借助黄病毒组反应性单克隆抗体、生物素化革抗鼠IgG抗体、金标SPA和金标亲合素,建立用DIGFA检测血清中登革病毒抗原的方法。结果常规DIGFA检测的敏感性高于病毒分离,而生物素一亲合素DIGFA(BA-DIGFA)的敏感性又高于常规的DIGFA。常规DIGFA可检测到5、0TCID50的病毒抗原,BA-DIGFA可检测到43TCID50的病毒抗原。结论作者建立的BA-DIGFA简便、快速、敏感、特异,可用于快速诊断登革病毒4型感染。 相似文献
995.
CT features of systemic lupus erythematosus in patients with acute abdominal pain: emphasis on ischemic bowel disease 总被引:13,自引:0,他引:13
Byun JY Ha HK Yu SY Min JK Park SH Kim HY Chun KA Choi KH Ko BH Shinn KS 《Radiology》1999,211(1):203-209
PURPOSE: To evaluate the computed tomographic (CT) features of systemic lupus erythematosus (SLE) in patients with acute abdominal pain. Special emphasis was placed on the analysis of ischemic bowel disease. MATERIALS AND METHODS: The authors retrospectively reviewed the images from 39 abdominal CT examinations performed in 33 patients with SLE and acute abdominal pain. Images were evaluated for bowel wall changes, mesenteric changes, fluid collection, retroperitoneal lymphadenopathy, peritoneal enhancement, and hepatomegaly as well as for changes in other abdominal organs. Ischemic bowel disease was diagnosed if at least three of the following signs were seen: bowel wall thickening, target sign, dilatation of intestinal segments, engorgement of mesenteric vessels, and increased attenuation of mesenteric fat. RESULTS: Thirty-one (79%) of the 39 examinations had CT findings diagnostic of ischemic bowel disease, including symmetric bowel wall thickening (n = 29), target sign (n = 26), and mesenteric vascular engorgement and haziness (n = 31). In 24 cases, bowel wall thickening was multifocal, with variable length, and did not appear to be confined to a single vascular territory. CONCLUSION: The most common CT finding in patients with SLE and acute abdominal pain is ischemic bowel disease. CT is useful for detecting the primary cause of gastrointestinal symptoms, planning treatment, and monitoring for infarction or perforation. 相似文献
996.
Tuberculosis versus lymphomas in the abdominal lymph nodes: evaluation with contrast-enhanced CT 总被引:24,自引:0,他引:24
Yang ZG Min PQ Sone S He ZY Liao ZY Zhou XP Yang GQ Silverman PM 《AJR. American journal of roentgenology》1999,172(3):619-623
OBJECTIVE: Tuberculosis in the abdominal lymph nodes may be difficult to distinguish from lymphomas. This study evaluated specific CT imaging criteria for differentiating these entities. MATERIALS AND METHODS: We retrospectively reviewed the anatomic distribution and CT enhancement patterns of disease in 69 patients, 26 (38%) with tuberculosis and 43 (62%) with untreated lymphomas involving abdominal lymph nodes. Of the patients with tuberculosis, five (19%) had disseminated disease and 21 (81%) had nondisseminated disease. Of the patients with lymphomas, 16 (37%) had Hodgkin's disease and 27 (63%) had non-Hodgkin's lymphoma. RESULTS: Disseminated and nondisseminated tuberculosis involved predominantly lesser omental, mesenteric, anterior pararenal, and upper paraaortic lymph nodes. Lower paraaortic lymph nodes were involved more often in Hodgkin's disease (15 patients [94%]), non-Hodgkin's lymphoma (24 patients [89%]), and disseminated tuberculosis (five patients [100%]) than in nondisseminated tuberculosis (one patient [5%]). Mesenteric lymph nodes were involved more often in disseminated tuberculosis (four patients [80%]) and nondisseminated tuberculosis (11 patients [52%]) than in Hodgkin's disease (one patient [6%]) (p < .01). Anatomic distribution was not different between disseminated tuberculosis and non-Hodgkin's lymphoma. Tuberculous lymphadenopathy commonly showed peripheral enhancement, frequently with a multilocular appearance, whereas lymphomatous adenopathy characteristically showed homogeneous attenuation (14 patients [87.5%] with Hodgkin's disease and 19 patients [70%] with non-Hodgkin's lymphoma [p < .01]). CONCLUSION: Our findings indicate that the anatomic distribution and specific enhancement patterns of lymphadenopathy seen on contrast-enhanced CT can be useful in differentiating between tuberculosis and untreated lymphomas of the abdominal lymph nodes. 相似文献
997.
Heterogeneous myocardial sympathetic denervation complicating diabetes has been invoked as a factor contributing to sudden unexplained cardiac death. In subjects with diabetic autonomic neuropathy (DAN), distal left ventricular (LV) denervation contrasts with preservation of islands of proximal innervation, which exhibit impaired vascular responsiveness. The aims of this study were to determine whether this heterogeneous pattern of myocardial sympathetic denervation occurs in a rat model of diabetes and to explore a potential association with regional fluctuations in myocardial nerve growth factor (NGF) protein. Myocardial sympathetic denervation was characterized scintigraphically using the sympathetic neurotransmitter analog C-11 hydroxyephedrine ([11C]HED) and compared with regional changes in myocardial NGF protein abundance and norepinephrine content after 6 and 9 months in nondiabetic (ND) and streptozotocin-induced diabetic (STZ-D) rats. In ND rats, no difference in [11C]HED retention or norepinephrine content was detected in the proximal versus distal myocardium. After 6 months, compared with ND rats, myocardial [11C]HED retention had declined in the proximal segments of STZ-D rats by only 9% (NS) compared with a 33% decrease in the distal myocardium (P < 0.05). Myocardial norepinephrine content was similar in both ND and STZ-D rats. At 6 months, LV myocardial NGF protein content in STZ-D rats decreased by 52% in the proximal myocardial segments (P < 0.01 vs. ND rats) and by 82% distally (P < 0.01 vs. ND rats, P < 0.05 vs. proximal segments). By 9 months, [11C]HED retention had declined in both the proximal and distal myocardial segments of the STZ-D rats by 42% (P < 0.01 vs. ND rats), and LV norepinephrine content and NGF protein were decreased in parallel. Therefore, 6 months of STZ-induced diabetes results in heterogeneous cardiac sympathetic denervation in the rat, with maximal denervation occurring distally, and is associated with a proximal-to-distal gradient of LV NGF protein depletion. It is tempting to speculate that regional fluctuations of NGF protein in the diabetic myocardium contribute to heterogeneous cardiac sympathetic denervation complicating diabetes. 相似文献
998.
窥镜下激光治疗前列腺增生症 总被引:2,自引:0,他引:2
目的 评价经尿道激光前列腺切除术(TULP)的疗效及其与前列腺大小的关系。方法 回顾分析了1988年至1998年10年,采用TULP治疗的469例前列腺增生症患者对手术技术、手术前后的症关改善情况进行比较,并对233例符合条件的患者TULP手术效果与前列腺大小的相关性进行了研究。结果 469例患者前列腺症状评分(IPSS)平均值由术前的26.7降到术后的14.2;最大尿流率平均值由6.2ml/s上 相似文献
999.
1000.
Model-based small area estimates of overweight prevalence using sample selection adjustment 总被引:1,自引:0,他引:1
Using a hierarchical model with an adjustment for sample selection, we estimate the overweight prevalence for adults, by states, using data from the Third National Health and Nutrition Examination Survey (NHANES III). A two-stage hierarchical model was selected to account for geographic variability of outcomes and to model possible overdispersion of estimates due to cluster sampling. We compare our model-based estimates with design-based estimates at the national level and obtain excellent agreement. We also provide a check of our model at the state level by comparing estimates with design-based and synthetic estimates. 相似文献