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   37381篇
  免费   3493篇
  国内免费   2654篇
耳鼻咽喉   434篇
儿科学   436篇
妇产科学   384篇
基础医学   4257篇
口腔科学   631篇
临床医学   5183篇
内科学   5287篇
皮肤病学   404篇
神经病学   2069篇
特种医学   1343篇
外国民族医学   26篇
外科学   3519篇
综合类   7188篇
现状与发展   12篇
预防医学   2319篇
眼科学   1142篇
药学   3820篇
  30篇
中国医学   2118篇
肿瘤学   2926篇
  2024年   153篇
  2023年   752篇
  2022年   1794篇
  2021年   2075篇
  2020年   1604篇
  2019年   1320篇
  2018年   1385篇
  2017年   1302篇
  2016年   1125篇
  2015年   1696篇
  2014年   2158篇
  2013年   1853篇
  2012年   2810篇
  2011年   2920篇
  2010年   1742篇
  2009年   1407篇
  2008年   1704篇
  2007年   1783篇
  2006年   1797篇
  2005年   1824篇
  2004年   1138篇
  2003年   1099篇
  2002年   962篇
  2001年   848篇
  2000年   858篇
  1999年   990篇
  1998年   646篇
  1997年   709篇
  1996年   527篇
  1995年   435篇
  1994年   372篇
  1993年   211篇
  1992年   281篇
  1991年   241篇
  1990年   211篇
  1989年   183篇
  1988年   171篇
  1987年   137篇
  1986年   101篇
  1985年   78篇
  1984年   34篇
  1983年   20篇
  1982年   27篇
  1981年   15篇
  1980年   8篇
  1979年   9篇
  1965年   2篇
  1940年   3篇
  1935年   2篇
  1934年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
BACKGROUND: In nonprimates, organ allografts are often not rejected after withdrawal of immunosuppression. In this study, we examined whether such a phenomenon also occurs in primates. METHODS: Vervet monkeys were transplanted with renal allografts and treated for 60 days with tacrolimus, or tacrolimus plus sirolimus. The drugs were totally withdrawn on day 61. The survival of the monkeys was monitored, and their response to donor- or third party-derived alloantigens was examined in vivo and in vitro. RESULTS: The majority (80-100%) of the grafts survived for at least additional 30 days with no signs of acute rejection. The compromised rejection is donor-specific, because recipient monkeys failed to reject a donor-derived skin graft, but a third-party skin graft was rejected. In vitro mixed lymphocyte reaction and interleukin-2 production in the mixed lymphocyte reaction between the recipients and their donors or between the recipients and a third party had no discernable patterns, and thus did not reflect the in vivo status of the immune system. Although the recipients could not reject the graft acutely after drug withdrawal, the kidney grafts and the donor-derived skin grafts had pathological findings of chronic rejection. CONCLUSIONS: The rejection response of the monkeys to an established graft after withdrawal of immunosuppression is compromised. The compromised rejection is specific and is not due to a permanent alteration of the immune system by the initial drug treatment. The allografts are not inert but have low levels of interaction with the recipient immune system.  相似文献   
92.
大肠癌患者骨髓微转移的基因研究   总被引:3,自引:1,他引:2  
Li S  Luo C  Yu B  Yuan S  Liang Z 《中华外科杂志》2000,38(3):196-197
目的 探讨大肠癌患者骨髓中微转移基因检测的意义。方法 应用聚合酶链式反应-单链构象多态性分析(PCR-SSCP)/银染技术,检测51例大肠癌患者手术前、后不同时间骨髓中p53和K-ras基因的突变状况。结果 51例患者术前骨髓中基因突变阳性者19例,阳性率37.25%。阳性检出与Duke’s分期、淋巴转移显著相关。术后经2~3个疗程的化疗后,19例基因突变阳性的患者中11例转阴。结论 大肠癌患者骨  相似文献   
93.
The SH2 domain-containing inositol 5'-phosphatase (SHIP) is crucial in hematopoietic development. To evaluate the possible tumor suppressor role of the SHIP gene in myeloid leukemogenesis, we examined primary leukemia cells from 30 acute myeloid leukemia (AML) patients, together with eight myeloid leukemia cell lines. A somatic mutation at codon 684, replacing Val with Glu, was detected in one patient, lying within the signature motif 2, which is the phosphatase active site. The results of an in vitro inositol 5'-phosphatase assay revealed that the mutation reduced catalytic activity of SHIP. Leukemia cells with the mutation showed enhanced Akt phosphorylation following IL-3 stimulation. K562 cells transfected with the mutated SHIP-V684E cDNA showed a growth advantage even at lower serum concentrations and resistance to apoptosis induced by serum deprivation and exposure to etoposide. These results suggest a possible role of the mutated SHIP gene in the development of acute leukemia and chemotherapy resistance through the deregulation of the phosphatidylinositol-3,4,5-triphosphate (PI(3,4,5)P3)/Akt signaling pathway. This is the first report of a mutation in the SHIP gene in any given human cancer, and indicates the need for more attention to be paid to this gene with respect to cancer pathogenesis.  相似文献   
94.
20只ICR小鼠经尾静脉途径人工感染泰泽氏菌。感染小鼠健康活泼,与对照小鼠无区别。感染后4-7天,lO只经醋酸可的松激发的小鼠其肝脏均表现出轻重不等的散在、灶性病变以至弥漫性灶性坏死,Gierasa染色镜检可见数量不等、典型的泰泽氏菌,细菌培养阴性。10只未经激发小鼠和5只对照小鼠均未见有病变,镜检也未查到泰泽氏菌。上述试验结果表明,泰泽氏菌在ICR小鼠体内的繁殖和形成肝脏病变与机体的免疫状态有密切关系。  相似文献   
95.
经去颧弓扩大颞下入路切除海绵窦,岩尖,上斜坡肿瘤   总被引:5,自引:0,他引:5  
本文介绍采用改进的去颧弓扩大颞下入路手术治疗8例位于或累及海绵窦、岩骨尖部、上斜坡、天幕游离前外缘肿瘤患者。该方法的要点是断去颧弓,扇形形成颞肌瓣,翻向颧弓断段以下,咬除蝶骨嵴外侧部分,形成低位颞额骨窗,仅轻度上抬颞叶,则可充分暴露病变范围。由于手术空间扩大,更利于肿瘤切除。本组8例均达到全部或大部分切除,患者术后均得以康复,原有体征不同程度改善。  相似文献   
96.
A hemopoietin with the ability to accelerate both platelet and granulocyte recovery after intensive chemotherapy would have great clinical utility. The recombinant fusion protein composed of human granulocyte-macrophage colony-stimulating factor and interleukin-3 (PIXY321), showed some promise in early adult trials. However, studies for pediatric patients are limited, and there are no systematic data on the pharmacokinetics of PIXY321 given over prolonged periods at current dosage levels. Purpose: To determine the safety, clinical effects and plasma concentrations of increasing doses of PIXY321 in children treated with myelosuppressive chemotherapy. Methods: A total of 39 children with relapsed or high-risk solid tumors were enrolled in this phase I/II study. PIXY321 was administered once or twice daily by subcutaneous injection in total doses of 500 to 1000 μg/m2 per day for 14 days after each course of chemotherapy with ifosfamide, carboplatin, and etoposide (ICE). Pharmacokinetic studies were performed on day 1 of the first course in 33 patients and repeated on day 14 in 13 patients (once-daily schedule only). Results: Although mild local skin reactions and fever were frequent, no dose-limiting toxicity was identified at the maximum dose studied (1000 μg/m2 per day). There were no statistically significant differences in chemotherapy-induced hematologic toxicity with increasing doses of PIXY321 or with twice-daily vs once-daily dosing. On day 1, the median PIXY321 clearance was 657 ml/min per m2 (range 77–1804 ml/min per m2) and the median half-life was 3.7 h (range 2.1–20.8 h). On day 14, clearance increased in all patients studied (median increase 63%), with a corresponding decrease in the median 12-h concentration (from 1.2 to 0.25 ng/ml). Maximum concentrations were <1 ng/ml in 81% of patients, and only two patients had maximum plasma concentrations equivalent to those required for consistent activity in vitro. Conclusions: The recombinant fusion protein PIXY321 proved safe in children treated with myelosuppressive ICE chemotherapy but had no demonstrable clinical benefits. The pharmacokinetic studies suggest that the observed lack of hematologic benefit may be explained by low plasma concentrations resulting from increased clearance with prolonged administration. Moreover, the significant increase in PIXY321 systemic clearance in the absence of increased circulating myeloid cells suggests that the upregulation of either extravascular compartment hematopoietic progenitor cells or nonhematopoietic cells may play an important role in controlling circulating concentrations of this unique cytokine. These findings highlight the importance of a thorough assessment of the systemic disposition of cytokines when determining the dose and schedule necessary to achieve clinical activity in patients. Received: 29 January 1997 / Accepted: 9 May 1997  相似文献   
97.
T抗原单克隆抗体法在大肠癌筛检中的应用初探   总被引:2,自引:0,他引:2  
目的 探讨T抗原单克隆抗体法在大肠癌筛检中的临床价值.方法 同时采用T抗原单克隆抗体法和半乳糖氧化酶法检测207例直肠粘液中的T抗原.结果 T抗原单克隆抗体法和半乳糖氧化酶法的敏感性和特异性分别为69.2%、67.3%和64.2%、65.6%,两者的筛检价值无明显差别.结论T抗原单克隆抗体法对大肠癌筛检有较大临床价值,且操作简便.  相似文献   
98.
我院在常规治疗方法上加用维生素B12治疗小儿急性肾小球肾炎40例,取得很好疗效,现报道如下。  相似文献   
99.
目的:探索孕激素在女性围绝经期情绪障碍中的作用.方法:研究对象以抑郁为主伴或不伴焦虑的围绝经期女性57例,及参加体检的、经Zung氏焦虑抑郁自评量表筛选后无抑郁焦虑症状群的围绝经期健康女性37例,两组年龄范围均介于40~60岁.主要评定工具为HAMD、HAMA、SAS、SDS等量表,并于入院后次晨空腹抽血检测孕激素.结果:HAMD、HAMA评分在女性围绝经期情绪障碍组和健康对照组之间存在着统计学差异(P<0.01);情绪障碍组的孕激素水平虽然略高于健康对照组,但两者之间差异无统计学意义(P>0.05);情绪障碍组的孕激素与HAMD评分之间没有相关性,而与HAMA评分之间有低度相关性(P<0.05).结论:孕激素在女性围绝经期情绪障碍的发生、发展中可能发挥着一定的作用.  相似文献   
100.
柴莪退热栓治疗急性病毒性上呼吸道感染临床研究   总被引:2,自引:1,他引:2  
目的观察柴莪退热栓治疗急性病毒性上呼吸道感染中医辨证属卫分证、卫气同病证的临床疗效,并探讨外感高热卫分证、卫气同病证证候与疗效间的关系.方法将患者 80例随机分为治疗组与对照组,分别予柴莪退热栓和消炎痛栓塞肛,并进行安全性评价.结果两组总体疗效相当,且未发现明显毒副作用.结论 柴莪退热栓治疗急性病毒性上呼吸道感染疗效满意.  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