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   39065篇
  免费   3913篇
  国内免费   2280篇
耳鼻咽喉   768篇
儿科学   353篇
妇产科学   878篇
基础医学   2682篇
口腔科学   374篇
临床医学   5697篇
内科学   7597篇
皮肤病学   735篇
神经病学   1538篇
特种医学   1630篇
外国民族医学   31篇
外科学   7120篇
综合类   6384篇
现状与发展   63篇
预防医学   1582篇
眼科学   769篇
药学   1953篇
  37篇
中国医学   608篇
肿瘤学   4459篇
  2024年   79篇
  2023年   1269篇
  2022年   2088篇
  2021年   2862篇
  2020年   2611篇
  2019年   1272篇
  2018年   1275篇
  2017年   1123篇
  2016年   1213篇
  2015年   1638篇
  2014年   2573篇
  2013年   2344篇
  2012年   2812篇
  2011年   2810篇
  2010年   2374篇
  2009年   2137篇
  2008年   1794篇
  2007年   2438篇
  2006年   2292篇
  2005年   1699篇
  2004年   1444篇
  2003年   1002篇
  2002年   777篇
  2001年   661篇
  2000年   503篇
  1999年   509篇
  1998年   355篇
  1997年   268篇
  1996年   144篇
  1995年   141篇
  1994年   109篇
  1993年   50篇
  1992年   113篇
  1991年   87篇
  1990年   119篇
  1989年   50篇
  1988年   39篇
  1987年   36篇
  1986年   32篇
  1985年   16篇
  1984年   5篇
  1983年   7篇
  1982年   10篇
  1981年   9篇
  1980年   6篇
  1974年   10篇
  1973年   5篇
  1971年   4篇
  1967年   4篇
  1966年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
多发性骨髓瘤合并肾功能不全38例临床和预后分析   总被引:5,自引:0,他引:5  
目的研究多发性骨髓瘤合并肾功能不全的临床特点及肾功能可逆性的相关因素和生存相关因素。方法回顾性分析1999-01~2003-12北京协和医院收治的91例初治多发性骨髓瘤及其中38例多发性骨髓瘤合并肾功能不全患者的临床资料。结果91例初治多发性骨髓瘤中有38例(41·8%)合并肾功能不全。合并肾功能不全的患者病程进展更快,贫血更严重,血乳酸脱氢酶(LDH)和β2-微球蛋白(β2-MG)质量浓度更高,以及尿蛋白量更多,同时对化疗的反应更差及生存时间更短。其中34·2%的患者肾功能不全是可逆的,血肌酐和LDH是肾功能可逆的独立预测因素。肾功能可逆患者的生存时间与肾功能正常患者的生存时间比较差异无显著性意义。Cox生存多因素分析发现肾功能可逆性(B=1·294,EXP(B)=3·647,P=0·001)是与生存惟一相关的因素。结论肾功能不全是多发性骨髓瘤常见并发症,相当一部分患者的肾功能可以恢复正常,血肌酐水平和LDH水平是肾功能可逆的重要因素,肾功能可逆性是独立的生存预后因素。  相似文献   
142.
Sixteen patients (male: 14, female: 2, 41-72 yrs, mean 57.5 yrs) with OSAS were treated by nCPAP in our hospital since 1987. Respiratory disturbance index ranged from 16.5 to 83.1. The longest apnea duration was 35.0-120.5 seconds before the treatment. Two patients were treated with Sleep Easy III (Respironics Inc.) and others with a home made instruments. nCPAP was set at a pressure of 5 to 10 cm H2O. 12 patients (75%) tolerated the device but 4(25%) did not. Polysomnographic parameters before and after nCPAP therapy were compared. The longest apnea duration was 63.1 +/- 23.5 to 40.9 +/- 27.4 seconds (P less than 0.001) and the lowest saturation oxygen was 55.1 +/- 20.4% to 71.4 +/- 18.6% (P less than 0.05). The sleep structure improved but not significant statistically. One of them used nCPAP at home for more than two. years and showed a good long term effect. We concluded that nCPAP is an effective and safe treatment for OSAS. However, patients may be uncomfortable because of the wearing of the nasal mask during sleep.  相似文献   
143.
输尿管口囊肿的微创手术治疗   总被引:12,自引:0,他引:12  
目的评价输尿管口囊肿的微创手术治疗方法及其疗效。方法回顾性分析25例行经尿道电切(TURU)手术治疗输尿管口囊肿患者资料。男9例,女16例;年龄18—61岁,平均38岁;单侧18例,双侧7例;单纯输尿管囊肿22例,异位输尿管囊肿3例。结果25例患者手术一次成功22例,手术平均时间15min,术后平均住院3d。术后定期B超、膀胱造影随诊,随诊时间1—9年,3例异位输尿管囊肿合并重复肾、输尿管畸形患者存在术后膀胱输尿管返流,2例再次行开放手术后痊愈。结论TURU是治疗成人输尿管口囊肿的有效方法;当合并存在重复肾输尿管畸形或术后膀胱输尿管返流时,应采用输尿管膀胱抗返流手术。  相似文献   
144.
目的 探讨Survivin在食管癌组织中的表达及其与bc1-2蛋白表达的相关性。方法应用免疫组织化学SP法,检测Survivin、bc1-2蛋白在68例食管癌组织和20例正常食管组织中的表达。结果 Survivin蛋白在正常食管组织中低表达或不表达,68例食管癌组织中,49例表达阳性,占72.1%。Survivin蛋白表达与分化程度、淋巴结转移密切相关(P〈0.05)。食管癌组织bc1-2蛋白表达阳性、阴性组中,Survivin蛋白阳性表达率分别为94.7%(36/38)和43.3%(13/30),两者比较.差异有统计学意义(P〈0.05)。Survivin蛋白表达与bc1-2蛋白表达密切相关。结论 Survivin在食管癌组织中表达上调,通过抑制细胞凋亡,在食管癌的发生中起到重要作用;凋亡相关基因bc1-2的上调与Survivin的表达可能在食管癌变中起协同作用。  相似文献   
145.
The role of MHC class Ⅱ transactivator (CⅡTA) in constitutive or IFN-γ inducib|e expression of HLA molecules in human malignant hematological cell lines was investigated. The expression of HLA molecules and CⅡTA protein was detected by Western blot, immunohistochemistry and flow cytometry. The expression of CⅡTA gene was determined by RT-PCR. The capability of peripheral blood T cell reaction stimulated by tumor cells was monitored by mixed lymphocyte reaction. It was found that the HLA Ⅱ-positive tumor cells expressed the CⅡTA quite well, andthe expression of HLA Ⅰ+Ⅱ was increased in the tumor cells with constitutive or inducible expression of CⅡTA after induced by IFN-γ. The tumor cells which did not express CⅡTA after in-duced by IFN-γ were not response to the expression of HLA Ⅱ promoted by IFN-γ. It suggests a correlation between the inability of some malignant hematological cell lines in response to IFN-γ for HLA expression and the deficiency in the inducible expression of CⅡTA, indicating CⅡTA might take part in the regu|ation of HLA Ⅰ+Ⅱ expression in the tumor cells, which might p|ay an important role in tumor immunologic escape.  相似文献   
146.
147.
148.
腕关节融合钢板内固定术的临床疗效   总被引:1,自引:0,他引:1  
目的评价腕关节融合钢板内固定术的临床疗效。方法2000年7月-2004年12月,采用腕关节融合钢板内固定术治疗创伤性腕关节炎21例。随访内容包括腕关节疼痛程度、手指关节活动度、握力和x线片。根据Buck—Gramcko/Lohrnanrm评分表评价腕关节总体功能,DASH调查表评价腕关节融合术对患者日常活动及生活质量的影响。结果术后21例获得随访,平均随访时间为20个月。术后患侧腕部疼痛值平均为1.5(术前4.5),12例掌指关节和lO例拇指指间关节出现轻微背伸功能障碍,腕部握力为30kg(健侧为38kg)。x线片示腕关节全部骨性融合。Buck—Gramcko/Lohmanrm评分值为8.7,其中优5例、良10例,中6例。DASH值为32,DASH调查表结果表明腕关节融合术后部分日常活动受限。结论腕关节融合钢板内固定成功率高,腕关节疼痛明显减轻,但术后腕关节部分功能丧失。  相似文献   
149.
FK506和RS-61443对大鼠异体肢体移植的联合免疫抑制作用   总被引:3,自引:0,他引:3  
目的 通过大鼠异体肢体移植模型 ,旨在分析 FK5 0 6和 RS- 6 14 4 3对大鼠异体肢体移植中急性排斥反应的免疫抑制作用。 方法 选择雄性 Wistar和 SD大鼠为供、受体 ,以 FK5 0 6和 RS- 6 14 4 3为免疫抑制剂 ,对照组为术后不用药组 ,实验组根据用药剂量和药物不同分为 6组 ,各组用药时间均为 5周 (每日 1次共 2周 ,然后每周 2次共 3周 ) ,进行了 10 1例异体肢体移植动物实验。观察大鼠一般情况、移植肢体排斥反应及存活时间。 结果 对照组肢体平均存活时间为 (7.0 0± 0 .78)天 ;实验组 1~ 6组移植肢体平均存活时间分别为 (17.0 8± 4 .5 0、2 3.2 0± 5 .0 5、11.19±2 .2 8、16 .33± 1.83、13.33± 3.2 2和 5 8.76± 6 .81)天。 结论  FK5 0 6和 RS- 6 14 4 3能抑制大鼠同种异体肢体移植术后急性移植排斥反应的发生 ,并能延长移植肢体的存活时间。  相似文献   
150.
BACKGROUND: The treatment of diffuse brain injury during an acute period is focused on relieving degrees of secondary brain injury. Generation and development of pathological changes of secondary brain injury depend on signal conduction, so down-regulating over response of astrocyte through interfering a key link of signal conduction pathway may bring a new thinking for the treatment of diffuse brain injury. OBJECTIVE: To observe the effect of over activity of extracellular signal regulated kinases 1/2 (ERK1/2) signal pathway on the response of astrocyte during an acute period of diffuse brain injury. DESIGN: Completely randomized grouping and controlled animal study. SETTINGS: Department of Neurosurgery, the Third Affiliated Hospital, Nanchang University; Department of Neurosurgery, Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology. MATERIALS: A total of 158 healthy male SD rats, of 11 weeks old, weighing 320–370 g, were provided by Experimental Animal Faulty, Tongji Medical College, Huazhong University of Science and Technology. Rabbit-anti-phosphorylated ERK1/2 (pERK1/2) polyclonal antibody was provided by R&D Company; rabbit-anti-glial fibrillary acidic protein (GFAP) polyclonal antibody, SP immunohistochemical kit and horseradish peroxidase (HRP)-labeled goat-anti-rabbit IgG by Santa Cruz Company; specific inhibitor U0126 of ERK1/2 signal pathway by Alexis Company. METHODS: The experiment was carried out in the Laboratory of Neurosurgery, Union Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology from September 2004 to March 2006. ① Detection of pERK1/2 expression: A total of 110 rats were randomly divided into sham operation group (n =5), model group (n =35), high-dosage U0126 group (n =35) and low-dosage U0126 group (n =35). Rats in the sham operation group were only treated with incision of epicranium and fixation of backup plate, but not hit. Rats in the model group were used to establish diffuse brain injury models based on Marmarou free falling body without drug intervention. Rats in the high- and low-dosage U0126 groups were injected into caudal vein with 0.1 and 0.05 mg/kg U0126, respectively, and then, rats were hit to establish injured models. Every 5 rats were collected from model, high- and low-dosage U0126 groups at 5, 30 minutes, 3, 12, 24, 72 hours and 7 days after diffuse brain injury to detect pERK1/2 expression in cortex of parietal lobe based on Western blot technique. ② Distribution of pERK1/2 and positive GFAP cells in brain tissue: Another 48 rats were randomly divided into sham operation group (n =3), model group (n =15), high-dosage U0126 group (n =15) and low-dosage U0126 group (n =15). The intervention and administration were dealt as the same as those mentioned above. Every 3 rats were collected from model, high- and low-dosage U0126 groups at 30 minutes, 3, 12, 24 and 72 hours after model establishment to observe the distribution of pERK1/2 and postive GFAP cells in brain tissue which was cut from coronal section at Bregma –4.8 mm layer with immunohistochemical staining. MAIN OUTCOME MEASURES: pERK1/2 expression in cortex of parietal lobe and distribution of pERK1/2 and positive GFAP cells in brain tissues. RESULTS: ① pERK1/2 expression: After diffuse brain injury, pERK1/2 expression in cortex of parietal lobe was rapidly increased in the model group, reached at peak at 5 minutes and then decreased gradually. But the expression was still in a high level until the 72nd hour and fallen to the basic level on the 7th day. pERK1/2 level was lower in high- and low-dosage U0126 groups than that in model group at various time points (P < 0.01); meanwhile, pERK1/2 level was lower in high-dosage U0126 group than that in low-dosage U0126 group. The results showed that there was a certain dosage dependence on pERK1/2 expression. ② Distribution of pERK1/2 and positive GFAP cells in brain tissue: Positive expression of pERK1/2 lasted in brain tissue from 30 minutes to 72 hours after diffuse brain injury (P < 0.05). In addition, from 30 minutes to 3 hours, brown-yellow stained cells were mainly distributed in plasma, but rarely in nucleus. A lot of positive cells had tree-like apophysis, which was similar to neurons. With the time passing by, more and more nuclei manifested positive stains; moreover, nuclei mainly manifested positive staining until 24 hours after diffuse brain injury. Immune-positive pERK1/2 cells were widely distributed in brain tissue, especially mainly in binding site between deep cortex and cerebral white matter, and then in hippocampus. In addition, ependymal cell and vascular endothelial cells of choroids plexus also manifested strongly positive staining. As compared with model group, positive cells were decreased gradually in high- and low-dosage U0126 groups. However, number of positive cells was less in high-dosage U0126 group than that in low-dosage U0126 group. CONCLUSION: Diffuse brain injury strongly induces the activity of ERK1/2 signal pathway and response of astrocyte; in addition, U0126 can inhibit response of glial cells during an acute period, and the effect manifests dosage dependence.  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