全文获取类型
收费全文 | 242137篇 |
免费 | 20455篇 |
国内免费 | 14383篇 |
专业分类
耳鼻咽喉 | 2177篇 |
儿科学 | 3036篇 |
妇产科学 | 4886篇 |
基础医学 | 28313篇 |
口腔科学 | 4209篇 |
临床医学 | 30867篇 |
内科学 | 39823篇 |
皮肤病学 | 2817篇 |
神经病学 | 13545篇 |
特种医学 | 8532篇 |
外国民族医学 | 96篇 |
外科学 | 26663篇 |
综合类 | 34118篇 |
现状与发展 | 48篇 |
一般理论 | 45篇 |
预防医学 | 15096篇 |
眼科学 | 6676篇 |
药学 | 24205篇 |
164篇 | |
中国医学 | 10934篇 |
肿瘤学 | 20725篇 |
出版年
2024年 | 709篇 |
2023年 | 3494篇 |
2022年 | 8686篇 |
2021年 | 11428篇 |
2020年 | 8388篇 |
2019年 | 7594篇 |
2018年 | 7990篇 |
2017年 | 6971篇 |
2016年 | 6664篇 |
2015年 | 10092篇 |
2014年 | 12699篇 |
2013年 | 11884篇 |
2012年 | 17535篇 |
2011年 | 19217篇 |
2010年 | 11718篇 |
2009年 | 9381篇 |
2008年 | 12762篇 |
2007年 | 12801篇 |
2006年 | 12369篇 |
2005年 | 12443篇 |
2004年 | 8604篇 |
2003年 | 7642篇 |
2002年 | 6613篇 |
2001年 | 5995篇 |
2000年 | 6120篇 |
1999年 | 6414篇 |
1998年 | 3650篇 |
1997年 | 3671篇 |
1996年 | 2788篇 |
1995年 | 2583篇 |
1994年 | 2230篇 |
1993年 | 1496篇 |
1992年 | 2290篇 |
1991年 | 1996篇 |
1990年 | 1665篇 |
1989年 | 1457篇 |
1988年 | 1266篇 |
1987年 | 1176篇 |
1986年 | 942篇 |
1985年 | 750篇 |
1984年 | 491篇 |
1983年 | 381篇 |
1982年 | 225篇 |
1981年 | 202篇 |
1980年 | 191篇 |
1979年 | 243篇 |
1978年 | 141篇 |
1977年 | 112篇 |
1976年 | 97篇 |
1974年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
11.
12.
晶体玻璃体视网膜联合手术治疗复杂性视网膜脱离 总被引:6,自引:2,他引:4
目的探讨玻璃体视网膜手术(vitreretinalsurgery,VR术)联合晶体切除/超声粉碎的效果。方法对81例(81只眼)应用晶体玻璃体视网膜联合手术(lenticular-vitreoretinalsurgery,LVR术)治疗的复杂性视网膜脱离进行回顾性分析。结果解剖性成功者64只眼(79.01%),功能性成功者45只眼(55.56%);手术成功率显著降低的原因是前部增殖性玻璃体视网膜病变(proliferativevitreo-retinopathy,PVR)(成功率42.86%,P<0.01)和术中/术后眼内出血(成功率58.82%,P<0.025)。结论LVR术是治疗复杂性视网膜脱离的主要方法;显著影响手术预后的因素是前部PVR和术中/术后眼内出血。 相似文献
13.
14.
15.
The effects of intracellular Ca2+ (Ca2+i) on K+ currents in hippocampal cells were examined using acutely isolated cells obtained from adult guinea pigs. Whole-cell voltage-clamp recordings were carried out in a configuration that allowed a continuous perfusion of the intracellular medium. Recording media were made to block inward currents and allowed selective activation of K(+)-dependent outward currents. Voltage-dependent outward currents consisted of an initial rapidly decaying component followed by a sustained component. The time constant of decay of the transient current was about 25 msec, and previous studies (Numann et al., 1987) showed that the kinetic and pharmacological properties of this current closely resembled the A current recorded in invertebrate neurons (Connor and Stevens, 1971; Thompson, 1982). Intracellular perfusion of hippocampal cells with a solution containing elevated Ca2+ (about 4.5 x 10(-4) M) elicited outward currents at the holding potential (-45 to -55 mV) and produced changes in voltage-dependent K+ currents. The transient outward current (IA) activated by depolarization was suppressed with increases in Ca2+i. Delayed, sustained K+ currents were greatly potentiated. Data also showed that, among the 3 effects elicited by Ca2+i, suppression of IA was most sensitive to Ca2+i elevation. Previous results (Numann et al., 1987) showed that IA had a lower threshold (about -45 mV) than sustained currents (about -40 mV). By using low levels of depolarization (-40 mV), IA can be selectively activated, and the suppressive effect of Ca2+i on IA was confirmed on the kinetically isolated IA.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
16.
Therapy of human cervical carcinoma with monoclonal antibody-Pseudomonas exotoxin conjugates. 总被引:1,自引:0,他引:1
Pseudomonas exotoxin A (PE) linked to the F(ab')2 fragment of 1H10, a murine monoclonal antibody recognizing a carbohydrate epitope of a glycoconjugate expressed on the surface of human cervical carcinoma tumor cells, was evaluated for in vitro and in vivo activity. PE can kill cells by ADP-ribosylating elongation factor 2 thus inhibiting protein synthesis. Disulfide- as well as thioether-linked immunotoxins (1H10-PE) killed cervical carcinoma cells in vitro and were 20-160 times more inhibitory to target than to control cells. Cell killing was antibody mediated as demonstrated by the reduction of 1H10-PE growth inhibition to target CaSki cells by free 1H10 F(ab')2. In addition, a control antibody immunotoxin was nontoxic to CaSki cells. Thioether-linked 1H10-PE administered either i.v. or i.p. suppressed the growth of established solid s.c. cervical carcinoma tumors xenografted in nude mice for over 30 days. Treatment with antibody alone or a control immunotoxin had no significant effect on tumor growth. Administration of immunotoxin i.p. was associated with less toxicity than administration i.v., but i.v. injections were more effective at suppressing the growth of established solid tumors. 相似文献
17.
Xiaoguang Chen Yi Li Lei Wang Mark Katakowski Lijie Zhang Jieli Chen Yongxian Xu Subhash C. Gautam Michael Chopp 《Neuropathology》2002,22(4):275-279
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain. 相似文献
18.
19.
通过深入分析我国中医药科学性研究中所存在的问题,依据协同学理论,提出了中医药科学性的理论基础是协同学的观点。基于此,阐释了中医药科学性的协同学解释,这在一定意义上为中医药科学性的研究提供了新的视角和有益的启示。 相似文献
20.
背景:与小肠黏膜下层等材料相比,脱细胞血管具有天然管状结构,与输尿管形态结构相近,替代输尿管时仅需端端吻合即可,手术操作简单,血管外壁光滑,获取及制备方法简便等优点。
目的:拟应用同种颈动脉血管无细胞基质体外构建输尿管。
设计、时间及地点:观察性实验,于2006-09/2008-06在上海交通大学医学院附属新华医院动物实验中心完成。
材料:长风杂交白猪由上海松联实验动物公司提供。上海交通大学医学院实验动物中心提供的健康成年大鼠8只,用于血管无细胞基质的动物毒性实验。
方法:剥去猪颈动脉血管外膜,PBS冲洗若干遍,然后将血管置于pH 7.1 的PBS中4 ℃下振荡清洗,0.5%十二烷基硫酸钠振荡24 h,后使用双蒸水4 ℃下反复振荡洗涤1周,每日换双蒸水2次。对于解剖过程中肌肉残留相对稍多的血管,在双蒸水洗涤前以混合消化液37 ℃下振荡消化约2 h,再行双蒸水洗涤。制备的无细胞基质置于青、链霉素溶液中,4 ℃保存,完成脱细胞支架制备。
主要观察指标:光镜及电镜观察脱细胞后管壁无细胞基质片的主要成分。将同种异体来源内皮祖细胞培养增殖后植入血管无细胞基质,观察细胞生长情况,并进行血管无细胞基质动物毒性实验。拉力实验了解血管无细胞基质材料的收缩性能。
结果:颈动脉血管无细胞基质中已无细胞成分,无细胞基质主要由胶原成分组成。扫描电镜未见该材料表面存在细胞及细胞碎片,同时发现该无细胞基质存在孔隙样结构。体外同种异体来源的内皮祖细胞培养增殖后植入血管无细胞基质,细胞黏附于无细胞基质。血管无细胞基质按毒性分级属于无毒级。拉力实验说明该无细胞基质具有一定的韧性和牵张性。
结论:采用胰酶和十二烷基硫酸钠制备的颈动脉血管无细胞基质材料无细胞残留,具有一定的韧性和牵张性,种植于其中的种子细胞具备一定的生长能力。 相似文献