全文获取类型
收费全文 | 42762篇 |
免费 | 3060篇 |
国内免费 | 795篇 |
专业分类
耳鼻咽喉 | 386篇 |
儿科学 | 2248篇 |
妇产科学 | 886篇 |
基础医学 | 3279篇 |
口腔科学 | 932篇 |
临床医学 | 5230篇 |
内科学 | 8074篇 |
皮肤病学 | 428篇 |
神经病学 | 1611篇 |
特种医学 | 1003篇 |
外国民族医学 | 1篇 |
外科学 | 3766篇 |
综合类 | 5984篇 |
现状与发展 | 1篇 |
预防医学 | 6160篇 |
眼科学 | 337篇 |
药学 | 3419篇 |
42篇 | |
中国医学 | 1380篇 |
肿瘤学 | 1450篇 |
出版年
2024年 | 165篇 |
2023年 | 1015篇 |
2022年 | 2037篇 |
2021年 | 2575篇 |
2020年 | 2234篇 |
2019年 | 2035篇 |
2018年 | 2002篇 |
2017年 | 1564篇 |
2016年 | 1517篇 |
2015年 | 1476篇 |
2014年 | 3136篇 |
2013年 | 2934篇 |
2012年 | 2566篇 |
2011年 | 2777篇 |
2010年 | 2204篇 |
2009年 | 2111篇 |
2008年 | 1969篇 |
2007年 | 1993篇 |
2006年 | 1514篇 |
2005年 | 1392篇 |
2004年 | 1098篇 |
2003年 | 902篇 |
2002年 | 608篇 |
2001年 | 580篇 |
2000年 | 433篇 |
1999年 | 435篇 |
1998年 | 335篇 |
1997年 | 328篇 |
1996年 | 270篇 |
1995年 | 270篇 |
1994年 | 267篇 |
1993年 | 202篇 |
1992年 | 208篇 |
1991年 | 177篇 |
1990年 | 155篇 |
1989年 | 141篇 |
1988年 | 109篇 |
1987年 | 113篇 |
1986年 | 96篇 |
1985年 | 95篇 |
1984年 | 94篇 |
1983年 | 63篇 |
1982年 | 74篇 |
1981年 | 56篇 |
1980年 | 48篇 |
1979年 | 39篇 |
1978年 | 40篇 |
1977年 | 43篇 |
1976年 | 35篇 |
1975年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
体重指数分级标准应用方法的探讨 总被引:1,自引:0,他引:1
目的探讨按照体重指数分级标准计算出的体重值应用表的实用价值。方法将身高作为选定变量,其变量值间距为1 cm,按照体重指数分级标准上、下限值,分别乘以身高2(m2),即求出相对应的体重(kg),依此制成应用表。判定时依据身高和实测的体重,对照应用表得出其体重指数分级范围。结果制成并列出以体重值查对其相对应危险值应用表。结论本查对表适用于大规模的预防性健康体检。在人体生长发育阶段能做到自身动态监测,对早期预防肥胖症具有积极作用。 相似文献
42.
目的 检测亚硒酸钠是否能够削弱或解除顺铂对植物血球凝激素(PHA)刺激的人体外周血淋巴细胞的增殖抑制。方法 用顺铂和亚硒酸钠单独或联合处理PHA刺激的人体外周血淋巴细胞,顺铂(0.05,0.20,0.50mg/L)在细胞培养24h时加入,亚硒酸钠(0.05mg/L)在不同处理中分别在细胞培养开始时加入或与顺铂同时加入;培养72h后检测转化淋巴细胞的有丝分裂指数。结果0.05mg/L亚硒酸钠在培养开始时加入,PHA刺激转化的淋巴细胞有丝分裂指数较对照增长42.8%(P<0.05),与顺铂同时加入,有丝分裂指数增长13.7%(P>0.05)。0.05与0.20mg/L顺铂处理细胞,有丝分裂指数未发生显性改变,当顺铂剂量为0.50mg/L时,细胞有丝分裂指数较对照降低54.5%(P<0.001)。亚硒酸钠预处理细胞可以解除0.50mg/L顺铂所致的细胞增殖抑制,使有丝分裂指数恢复正常,但亚硒酸钠与顺铂同时加入时,被顺铂抑制的有丝分裂指数只能部分提高。结论0.05mg/L亚硒酸钠单独作用于淋巴细胞可直接促进细胞增殖,与顺铂联合处理细胞时,可降低顺铂毒性,拮抗顺铂的抗增殖作用。亚硒酸钠在细胞培养开始时加入培养体系效果更佳。 相似文献
43.
A. Taytard J. F. Tessier J. G. Faugere J. Vergeret P. Freour 《European journal of epidemiology》1988,4(3):326-330
Professional exposure to vegetable dusts affect the respiratory function of the exposed subjects. A previous survey conducted in an industrial flour-mill demonstrated a higher frequency of respiratory symptoms in workers compared to a control group. Ten subjects employed in a work site particularly exposed to dust were studied. Each subject answered a questionnaire and performed on Mondays and Fridays, at the begenning and end of his work shift, a flow volume curve and an isocapnic hyperventilation test. The aerobiology of the professional environment was also measured. We noted: 1) in the flow volume curves: a drop in the FEV1 during the Monday morning shift, a significant difference between the FEV1 (p<0.05) and the MMEFR 25–75 (p<0.05) measured at 6 am on Monday and Friday, and between the MMEFR 25–75 values obtained at 12 noon on Monday and Friday (p<0.05). 2) after isocapnic hyperventilation, a significant drop in the MMEFR 25–75 at 6 am on Monday (p<0.01) and in the FEV1 and MMEFR 25–75 at 12 noon on Mondays (p<0.05), a significant drop in the FEV1 at 1 pm on Monday (p<0.01). 相似文献
44.
45.
PGA指数和透明质酸在诊断慢性乙肝肝纤维化中的价值 总被引:1,自引:0,他引:1
目的:寻找一种简便实用的诊断慢性乙型肝炎纤维化的方法。方法:以78例经肝穿刺病理证实的慢性乙型肝炎为对象,测定并比较了由PT、GGT、ApoA1组成的PGA指数和HA、LN、PⅢP、C-IV与肝内纤维化程度(S)和炎症活动度(G)的关系。结果:(1)LN、PⅢP、C-IV在轻度慢性乙肝时无明显升高,在中度慢性乙肝时明显高于正常,但与轻度慢性乙肝无差异,而PGA指数和HA不仅在轻度慢性乙肝时显著升高,而且在轻中度间差异明显.因重度慢性乙肝和活动性肝硬化时,五项指标均显著增高。(2)在G2-4期,HA、LN、PⅢP、C-IV均明显高升,但在G1期,只有PGA指数高于正常,且各期间差异显著。(3)在S1-2期,只有PGA指数、HA、C-IV明显上升,但C-IV的上升幅度远低于PGA指数和HA。(4)加以PGA>4.5或HA>200μg/L作为判断临界值,则两者判断肝纤维化的敏感性均>94%,精确性>91%,特异性>86%,如两者结合,则分别达到98.3%、95.2%和96.4%。结论:PGA指数和HA均是反映慢性乙型肝炎患者肝内纤维化程度的良好指标,两者联合检测则可达到最大的价值效益比。 相似文献
46.
EVA ÅKERLÖF B. FREDRICSON O. GUSTAFSSON A. LUNDIN† N. O. LUNELL L. NYLUND L. ROSENBORG Å. POUSETTE 《International journal of andrology》1987,10(5):663-669
Two methods of separating human sperm were compared using twenty-two semen samples. The sperm were separated by a swim-up technique or by self-migration on a Percoll gradient followed by medium change. After separation, the sperm obtained were assessed for progressive motility, ATP content, energy charge index ([ATP + 0.5 ADP]/[ATP + ADP + AMP]) and morphology. In general, and especially for semen samples containing less than 20 X 10(6) sperm/ml, separation by Percoll gradient selected sperm that were superior to those separated by the swim-up technique. The relatively high energy charge index (greater than 0.8) showed that the sperm tolerated the separation conditions well. It is suggested that self-migration on a Percoll gradient should prove useful for obtaining sperm of high quality. 相似文献
47.
Marcos Ribeiro Luciene Angelini Priscila Games Robles-Ribeiro Rafael Stelmach Ubiratan de Paula Santos Mario Terra-Filho 《The Journal of asthma》2007,44(5):371-375
Background. The European Community Respiratory Health Survey (ECRHS) questionnaire was planned to answer questions about the distribution of asthma. Our objective was to determine the cultural equivalence of the ECRHS into the Brazilian-Portuguese language. Methods. We translated the ECRHS according to international criteria. Results. Small cultural adaptations were necessary. Among the 80 participating patients, the Cronbach indices were higher (0.98-1.00) and the Kappa indices varied from 0.77 to 1.00. Conclusion. The study suggests that the Brazilian version of the ECRHS is conceptually equivalent to the original and similarly reliable and may be used in international studies involving Portuguese-speaking respiratory patients. 相似文献
48.
Despite evidence from previous unit recording, microstimulation, lesioning and anatomical studies, the functions of the midbrain periaqueductal gray (PAG) remain unclear. We attempted to clarify the function of the PAG by recording activity of PAG units along with laryngeal and respiratory electromyograms (EMG) during vocalization in awake monkeys. PAG units were classified with respect to vocalization on the basis of their discharge patterns as 'early burst', 'late burst', 'tonic-increase' and 'tonic-off', with the vast majority being of the early- and late-burst type. Early-burst cells were correlated most frequently with inspiratory muscles of the respiratory system and laryngeal abductor muscles. Late-burst cells were most clearly correlated with laryngeal adductor and expiratory respiratory muscles. Data from spike-triggered averaging and parametric correlations indicate that most cells are related to single muscles, but a significant number were related to functionally related groups of two or more muscles. The results suggest that the PAG determines qualitative aspects of vocalization by the multisynaptic action its cells have on laryngeal and respiratory motoneurons. 相似文献
49.
免疫组化法检测非甲-非庚型肝炎患者肝组织中输血传播病毒 总被引:1,自引:1,他引:0
目的 检测非甲-非庚型肝炎患者肝组织输血传播病毒(TTV)感染状况,TTV感染与肝组织炎症程度 及与血液学指标的相关性。方法 应用免疫组织化学法检测52例非甲-非庚型肝炎患者肝组织中TTV,并经原位 杂交证实;对TTV阳性和阴性组的血液学生化指标,诸如血清丙氨酸转氨酶(ALT)、血清天冬氨酸转氨酶(AST)、血 清总胆红素(TBIL)、白蛋白(ALB)、γ 球蛋白(γ G)、凝血酶原活动度(PTA)及组织学活动指数(HAI)进行了比较。 结果 非甲-非庚型肝炎患者肝组织中TTV抗原(TTVAg)阳性15例,检出率为28.8%;阳性物质主要定位于肝细 胞浆内,呈棕黄色细小颗粒,偶见肝细胞核内有表达;TTV阳性表达细胞呈单个、散在或片簇状分布;TTVAg阳性的 组织切片经苏木素-伊红(HE)染色后,可观察到病毒性肝炎的一些病理变化,如肝细胞胞浆疏松化、气球样变、嗜酸 样变、灶性坏死、凋亡、小叶内及汇管区炎细胞浸润;从15例TTVAg阳性病例中任选10例进行TTV DNA原位杂交 检测,结果8例阳性,二者符合率80.0%;同时对5例免疫组化TTVAg阴性肝组织进行TTV DNA原位杂交检测,结 果5例均为阴性,二者符合率100%;TTVAg阳性组ALT、AST、TBIL、γ G均值均高于TTVAg阴性组,ALB、PTA 均值均低于TTVAg阴性组,但两组比较差异无统计学意义(P>0.0 相似文献
50.
P Sundaresan R Yeghiaian-Alvandi V Gebski 《Journal of Medical Imaging and Radiation Oncology》2010,54(1):69-75
Palliative whole brain radiotherapy (WBRT) is often recommended in the management of multiple brain metastases. Allowing for WBRT waiting time, duration of the WBRT course and time to clinical response, it may take 6 weeks from the point of initial assessment for a benefit from WBRT to manifest. Patients who die within 6 weeks (‘early death’) may not benefit from WBRT and may instead experience a decline in quality of life. This study aimed to develop a prognostic index (PI) that identifies the subset of patients with lung cancer with multiple brain metastases who may not benefit from WBRT because of ‘early death’. The medical records of patients with lung cancer who had WBRT recommended for multiple brain metastases over a 10-year period were retrospectively reviewed. Patients were classified as either having died within 6 weeks or having lived beyond 6 weeks. Potential prognostic indicators were evaluated for correlation with ‘early death’. A PI was constructed by modelling the survival classification to determine the contribution of these factors towards shortened survival. Of the 275 patients recommended WBRT, 64 (23.22%) died within 6 weeks. The main prognostic factor predicting early death was Eastern Cooperative Oncology Group (ECOG) status >2. Patients with a high PI score (>13) were at higher risk of ‘early death’. Twenty-three per cent of patients died prior to benefit from WBRT. ECOG status was the most predictive for ‘early death’. Other factors may also contribute towards a poor outcome. With further refinement and validation, the PI could be a valuable clinical decision tool. 相似文献