全文获取类型
收费全文 | 6555篇 |
免费 | 659篇 |
国内免费 | 183篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 223篇 |
妇产科学 | 103篇 |
基础医学 | 575篇 |
口腔科学 | 141篇 |
临床医学 | 794篇 |
内科学 | 804篇 |
皮肤病学 | 238篇 |
神经病学 | 259篇 |
特种医学 | 241篇 |
外科学 | 627篇 |
综合类 | 1141篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 849篇 |
眼科学 | 77篇 |
药学 | 649篇 |
2篇 | |
中国医学 | 336篇 |
肿瘤学 | 286篇 |
出版年
2023年 | 48篇 |
2022年 | 124篇 |
2021年 | 221篇 |
2020年 | 140篇 |
2019年 | 120篇 |
2018年 | 118篇 |
2017年 | 126篇 |
2016年 | 133篇 |
2015年 | 177篇 |
2014年 | 245篇 |
2013年 | 281篇 |
2012年 | 450篇 |
2011年 | 482篇 |
2010年 | 437篇 |
2009年 | 412篇 |
2008年 | 427篇 |
2007年 | 420篇 |
2006年 | 407篇 |
2005年 | 304篇 |
2004年 | 260篇 |
2003年 | 191篇 |
2002年 | 184篇 |
2001年 | 195篇 |
2000年 | 188篇 |
1999年 | 104篇 |
1998年 | 57篇 |
1997年 | 32篇 |
1996年 | 31篇 |
1995年 | 33篇 |
1994年 | 42篇 |
1993年 | 45篇 |
1992年 | 60篇 |
1991年 | 41篇 |
1990年 | 62篇 |
1989年 | 68篇 |
1988年 | 68篇 |
1987年 | 50篇 |
1986年 | 38篇 |
1985年 | 48篇 |
1984年 | 50篇 |
1983年 | 26篇 |
1982年 | 23篇 |
1981年 | 24篇 |
1979年 | 27篇 |
1978年 | 23篇 |
1976年 | 25篇 |
1974年 | 31篇 |
1973年 | 28篇 |
1972年 | 28篇 |
1967年 | 24篇 |
排序方式: 共有7397条查询结果,搜索用时 175 毫秒
71.
目的探讨药物(含氮二膦酸盐联合IL-2,N-BP/IL-2)诱导实体肿瘤患者外周血γδT细胞增殖作用。方法采用流式细胞仪测定103例肿瘤患者和43例健康人外周血总T细胞绝对值、御细胞绝对值和相对值,测定患者外周血经药物体外刺激后御细胞增殖指数和用药前后患者外周血总T细胞、γδT细胞绝对值和相对值。结果肿瘤患者和健康人外周血总T细胞绝对值、御细胞绝对值和御细胞相对值的中位数,分别为1306细胞/μl和1522细胞/μlP=0.003),64细胞/μl和162细胞/μl(P〈0.001),5%和11%(P〈0.001)。24例经药物体外扩增试验阳性的肿瘤患者治疗前后体内外周血总T细胞绝对值、γδT细胞绝对值和御细胞相对值的中位数,分别为1283细胞/μl和1552细胞/μl(P=0.001),54细胞/μl和107细胞/μl(P〈0.001),6%和8%(P=0.008)。全部肿瘤患者中外周血γδT细胞对药物体外诱导增殖反应阳性患者的百分率为68.9%。结论肿瘤患者外周血γδT细胞计数显著低于健康人。不同肿瘤患者外周血γδT细胞对药物刺激增殖的反应性不同。N-PB/IL-2在体内有显著增加御细胞数量的药理作用。体外增殖试验可作为N-PB/IL-2治疗患者的参考。 相似文献
72.
73.
Zinc toxicity in the ferret 总被引:1,自引:0,他引:1
74.
二十碳五烯酸联合视黄酸对HL-60细胞凋亡相关基因表达的影响 总被引:3,自引:1,他引:3
目的 研究二十碳五烯酸(EPA)是否协同视黄酸(RA)影响HL-60细胞的凋亡及相应分子机制。方法 流式细胞仪(FCM)检测细胞周期相分布以测定细胞增殖和凋亡功能;Western blot法分析bcl-2和caspase—3表达。结果 与单独应用相比,EPA和RA联合应用可增强HL-60细胞的调亡效应,以及下调节bcl—2和增强caspase-3基因表达。结论 EPA和RA联合应用对HL-60细胞凋亡的增强效应,可能与它们增强caspase-3和降低bcl—2基因表达相关。 相似文献
75.
细胞内外膜跨膜电位频率响应模型及滤波器特性的研究 总被引:2,自引:0,他引:2
提出球形单细胞内外膜跨膜电位频率响应模型和仿真计算方法。通过对频率响应的仿真分析,发现内外膜跨膜电位分别表现出一阶带通和低通滤波器特性,并在内膜频率响应中心频率到上限截止频率的范围内,内膜跨膜电位大于外膜同时能保持在较高水平,这将有利于诱导细胞内电处理效应。计算结果与动物实验吻合得很好,为纳秒脉冲电场治疗肿瘤的窗口参数合理选择提供了理论依据。 相似文献
76.
纳秒级陡脉冲电场诱导癌细胞凋亡的实验及作用机理研究 总被引:3,自引:1,他引:3
观察纳秒级陡脉冲电场诱导人浆液囊腺性卵巢癌SKOV3癌细胞凋亡效应,及其对细胞内钙离子浓度即[Ca2+]i的影响并探讨其作用机理。采用场强为10kV/cm、脉宽为100ns、重复频率为1Hz的纳秒级陡脉冲电场作用于SKOV3癌细胞悬液5min。4h后采用Annexin V-FITC/PI双标记并结合流式细胞仪分析SKOV3癌细胞的凋亡率,采用扫描和透射电子显微镜观察癌细胞凋亡的超微结构变化;以Fluo-3/AM为细胞内钙离子的荧光指示剂,用激光扫描共聚焦显微镜检测纳秒级陡脉冲电场对SKOV3癌细胞[Ca2+]i的影响,及[Ca2+]i变化时的Ca2+来源。结果显示,流式细胞术检测到癌细胞的早期凋亡率为(22.21±2.71)%,明显高于对照组的(3.04±0.44)%(P〈0.01),扫描和透射电子显微镜均观察到典型的凋亡细胞形态,证实纳秒级陡脉冲电场能够有效诱导SKOV3癌细胞发生凋亡;同时纳秒级陡脉冲电场可明显升高细胞[Ca2+]i(P〈0.01),而与细胞外钙离子浓度无关(P〉0.05)。由于纳秒级陡脉冲电场的等值频率很高,容易穿透细胞膜,其诱导凋亡的机制之一可能是通过激活细胞内钙库(内质网、线粒体),引起细胞内钙离子升高,从而介导凋亡信号通路。 相似文献
77.
Acquired C1 esterase inhibitor deficiency or serendipity? The chance finding of a paraprotein after an apparently low C1 esterase inhibitor concentration
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Acquired C1 esterase inhibitor deficiency is a rare condition, usually presenting after the 2nd decade of life, and is often related to underlying conditions such as autoimmune and lymphoproliferative disorders. This case report describes a man whose initial clinical presentation with acute angioedema and whose initial estimation of a low C1 esterase inhibitor concentration indicated that he had an acquired angioedema, possibly secondary to a B cell neoplasm. A paraprotein was detected, and although its detection was serendipitous because it hinged on a spurious C1 esterase inhibitor result, this case confirms the role of C4 concentrations in the investigation of C1 esterase inhibitor deficiency. It also confirms the need to obtain repeat confirmatory samples before arriving at a diagnosis, however convincing the clinical signs may be. 相似文献
78.
M A Sarraj P J McClive H P Wilmore K L Loveland A H Sinclair 《Developmental dynamics》2005,234(4):1026-1033
In an effort to understand the mechanisms that underpin gonadal differentiation at the time of sex determination, we identified a cDNA encoding a putative novel testis expressed scavenger receptor, Tesr. Based on its domain structure, we hypothesize that the function of Tesr is similar to that of other scavenger receptors that play roles in phagocytosis of apoptotic cells, cell-cell adhesion, and defense. Tesr mRNA was detected in fetal mouse gonads of both sexes at 11.5 days post coitum (dpc). From 12.0 dpc, Tesr expression rapidly decreased in the female and was maintained in the male. Expression was seen in embryonic mouse sites other than the testis, such as in brain, eye, head, heart, neural arch, and cartilage primordium. Tesr expression in the newborn testis was faint to undetectable, but it increased from 2 days postpartum (dpp) until 15 dpp and was found in a subset of interstitial cells and in germ and Sertoli cells. Tesr mRNA in the adult mouse testis was observed in Sertoli cells, spermatogonia, spermatocytes, round spermatids, and in a subset of interstitial cells. We conclude that Tesr is differentially expressed in the male vs. female embryonic gonad and is expressed in both the ovary and the testes postnatally after 2 dpp. 相似文献
79.
Hormone replacement therapy can successfully treat menopausal symptoms. A postal questionnaire was used to investigate the knowledge of and attitudes to hormone replacement therapy of an age-stratified, computer-generated, representative sample of 1500 women living in the Grampian region of Scotland. A response rate of 78% was achieved. Comparisons were made between women of differing age, educational background and their current or past experience of hormone replacement therapy. The questionnaire also assessed their knowledge of osteoporosis, including the possible beneficial role of hormone replacement therapy. The results showed that women had a poor knowledge of the potential risks and benefits of oestrogen, lack of knowledge being greatest in the less educated and older women. The majority of women agreed with the view that because the menopause is brought on by diminished hormone levels, it should be viewed as a medical condition and treated as such, and also that a woman who experiences distressing menopausal symptoms should take hormone replacement therapy. Despite this, relatively few postmenopausal women were currently taking hormone replacement therapy (9%) or had taken the treatment in the past (7%), although many had experienced menopausal symptoms for over six months. The most common reason for postmenopausal women never having taken hormone replacement therapy was that they had never considered the treatment (70%) and had not discussed it with a doctor (79%).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
80.
Composite carcinoma-carcinoid tumors of the gastrointestinal tract. A morphologic, histochemical, and immunocytochemical study 总被引:1,自引:0,他引:1
R S Klappenbach R J Kurman C F Sinclair L P James 《American journal of clinical pathology》1985,84(2):137-143
A morphologic, histochemical, and immunocytochemical study of 20 cases of pure gastrointestinal carcinoids, adenocarcinomas, and mixed neoplasms composed of both elements, so-called composite carcinoma-carcinoid tumors (CCC), was undertaken in order to correlate the morphologic patterns with the immunocytochemical localization of carcinoembryonic antigen (CEA), serotonin, and a battery of polypeptide hormones (calcitonin, glucagon, insulin, gastrin, somatostatin, and adrenocorticotropin [ACTH]). Paraffin sections from five pure carcinoids, seven pure adenocarcinomas, and eight CCC from the stomach, small bowel, appendix, and colon were studied with mucicarmine, silver impregnation stains, and a peroxidase-anti-peroxidase technic. Of the eight CCC, all were mucin positive, four were argyrophilic, and three were argentaffin positive. CEA was present in all eight, serotonin in seven, and calcitonin in one. No other neurohormonal peptides were demonstrated. The distribution of serotonin and CEA generally corresponded to the morphologic pattern, but discordance was observed in two cases, i.e., serotonin was not always localized to areas of carcinoid and CEA not always confined to areas of carcinoma. All five pure carcinoids demonstrated intracytoplasmic localization of serotonin, whereas none contained intracytoplasmic CEA. In two cases, CEA was present within acinar lumens only. The seven colonic adenocarcinomas were argyrophil and argentaffin negative. All contained CEA within the cytoplasm and in gland lumens. None contained serotonin. None of the neurohormonal peptides was localized in either pure adenocarcinomas or carcinoids. This study reveals that among gastrointestinal neoplasms displaying morphologic patterns of adenocarcinoma and carcinoid, immunocytochemical localization of CEA and serotonin confirms their bidirectional differentiation and justifies the designation "composite carcinoma-carcinoid." 相似文献