全文获取类型
收费全文 | 44453篇 |
免费 | 3790篇 |
国内免费 | 3062篇 |
专业分类
耳鼻咽喉 | 354篇 |
儿科学 | 670篇 |
妇产科学 | 626篇 |
基础医学 | 5526篇 |
口腔科学 | 707篇 |
临床医学 | 5880篇 |
内科学 | 7298篇 |
皮肤病学 | 461篇 |
神经病学 | 2775篇 |
特种医学 | 1379篇 |
外国民族医学 | 17篇 |
外科学 | 4876篇 |
综合类 | 6773篇 |
现状与发展 | 5篇 |
一般理论 | 7篇 |
预防医学 | 2674篇 |
眼科学 | 1211篇 |
药学 | 4436篇 |
31篇 | |
中国医学 | 1861篇 |
肿瘤学 | 3738篇 |
出版年
2024年 | 142篇 |
2023年 | 669篇 |
2022年 | 1714篇 |
2021年 | 2197篇 |
2020年 | 1598篇 |
2019年 | 1537篇 |
2018年 | 1597篇 |
2017年 | 1373篇 |
2016年 | 1282篇 |
2015年 | 1912篇 |
2014年 | 2388篇 |
2013年 | 2154篇 |
2012年 | 3224篇 |
2011年 | 3456篇 |
2010年 | 2061篇 |
2009年 | 1685篇 |
2008年 | 2330篇 |
2007年 | 2370篇 |
2006年 | 2230篇 |
2005年 | 2241篇 |
2004年 | 1525篇 |
2003年 | 1478篇 |
2002年 | 1248篇 |
2001年 | 1104篇 |
2000年 | 1122篇 |
1999年 | 1231篇 |
1998年 | 655篇 |
1997年 | 713篇 |
1996年 | 530篇 |
1995年 | 480篇 |
1994年 | 411篇 |
1993年 | 299篇 |
1992年 | 367篇 |
1991年 | 321篇 |
1990年 | 272篇 |
1989年 | 238篇 |
1988年 | 219篇 |
1987年 | 188篇 |
1986年 | 168篇 |
1985年 | 124篇 |
1984年 | 69篇 |
1983年 | 78篇 |
1982年 | 47篇 |
1981年 | 53篇 |
1980年 | 29篇 |
1979年 | 44篇 |
1978年 | 20篇 |
1977年 | 17篇 |
1974年 | 18篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 2 毫秒
991.
目的:比较研究不同代次间兔半月板纤维软骨细胞生物学特性的改变,为构建组织工程半月板和细胞治疗中的种子细胞优选提供进一步的理论和实践基础。方法:采用机械分离与酶连续消化相结合的方法体外分离兔半月板纤维软骨细胞,单层培养传代至第5代。采用相差倒置显微镜和SEM观察各代细胞的形态变化和超微结构,MTT法检测细胞增殖情况并描绘生长曲线,采用细胞化学染色和免疫组化鉴定细胞分泌的蛋白聚糖和Ⅰ、Ⅱ型胶原蛋白。结果:半月板纤维软骨细胞原代接种后8~12 h开始贴壁,48~72h大部分细胞贴壁,胞质逐渐展开,细胞变大伸长,形成突起,呈多角形,细胞形态规则,轮廓清晰,镜下观察有立体感,7~10 d后,细胞长满传代。传代后细胞贴壁生长能力和增殖速度明显加快,原代至第2代细胞形态较规则,多呈多角形,大小均一。第3代后随着传代次数的增加,细胞中梭形细胞增多,分泌和增殖能力下降,传代周期延长。第5代分裂相少见,密度稀疏,细胞形态不佳,约80%呈长梭形,分泌和增殖能力下降。SEM示第1代半月板细胞形态规则,呈多极性,表面有突起;第5代细胞形态不规则,多呈梭形。生长曲线可见第4代前半月板细胞生长速度及生长周期均相似,第5代后细胞生长速度减慢,增殖减缓。细胞化学和免疫组化染色分析胶原和蛋白聚糖的表达:随传代的进行,Ⅱ型胶原蛋白和蛋白聚糖的表达逐渐减弱而Ⅰ型胶原表达逐渐增强。结论:体外单层培养条件下,随着传代的进行,细胞活力逐渐下降,生长速度减慢,传代周期延长,逐渐变为梭形,形态不规则。体外单层培养系统中半月板纤维软骨细胞表型随传代的进行,Ⅱ型胶原蛋白和蛋白聚糖的表达逐渐减少而Ⅰ型胶原表达逐渐增多,体外单层培养条件下培养的半月板纤维软骨细胞从第3代开始逐渐失去其特异性表型,发生去分化,逐渐变为成纤维细胞的表型。体外单层分离培养的第5代前半月板细胞基本维持纤维软骨细胞的表型和生物学特性,可作为组织工程半月板的种子细胞。 相似文献
992.
目的 探讨原代大鼠雪旺细胞(SCs)在不同拓扑结构的聚甲基丙烯酸甲酯(PMMA)电纺纳米纤维上生长的特点,为后续在体研究提供基础.方法 构建具有随机或有序拓扑结构的PMMA电纺纳米纤维,并测定其生物相容性;利用PMMA薄膜组作为对照,利用慢病毒载体转染绿色荧光蛋白基因作为显色手段,分析SCs在随机及有序纤维支架上的细胞形态和生长方向,以及胞体及突起与纤维结构的依存关系. 结果 构建的PMMA电纺纳米纤维具有良好的生物相容性,SCs在随机及有序电纺纤维上均能顺利贴壁并生长;电纺纤维的拓扑结构能够影响SCs的细胞形态,与在PMMA薄膜及随机电纺纤维上相比,在有序纤维系统上的SCs能够形成更长且与纤维延伸方向一致的细胞突起(P<0.01).相比随机电纺纤维,有序纳米纤维对原代SCs的生长更具引导作用. 结论 PMMA有序电纺纳米纤维具有作为神经损伤后植入性SCs支架的潜力. 相似文献
993.
目的探讨手术改善非小细胞肺癌(NSCLC)合并脑转移患者的预后。方法对我院2005年3月—2013年5月切除NSCLC原发灶的62例患者进行分析,分析原发病灶的部位、手术方法、病理分型,脑转移灶的数量、治疗方式、治疗后的生存期等。结果本组男21例,女41例。全肺切除4例,肺叶、肺段或肺部分切除58例。腺癌47例(75.8%),鳞癌8例,混合型腺鳞癌7例。在处理脑转移瘤后再切除原发灶38例,先处理原发灶者24例。本组中位生存期18.7个月。其中1年生存率为75.9%;2年生存率为38.9%;3年生存率为16.7%。与同期未手术对照组比较1年生存率无差异,2、3年生存率比较差异有统计学意义(P<0.01)。结论积极处理肺部原发灶,结合头部放疗及全身化疗或基因靶向等综合治疗可延长生存期,提高此类患者预后。 相似文献
994.
Xiaodong Tang Wei Guo Rongli Yang Shun Tang Tao Ji 《Clinical orthopaedics and related research》2015,473(4):1464-1471
BackgroundShoulder function often is limited after tumor resection and endoprosthetic replacement of the proximal humerus. This is partly attributable to the inability to reliably reattach rotator cuff tendons to the prosthesis and achieve adequate shoulder capsule repair with a metallic prosthesis. An option to attain these goals is to use synthetic mesh for the reconstruction, although the value of this method has not been well documented in the literature.Questions/purposesWe asked whether patients who had shoulder reconstruction using synthetic mesh had (1) better shoulder function; (2) improved ROM compared with shoulder reconstructions without mesh; and (3) more stable joints compared with those in patients with similar resections who had reconstructions without synthetic mesh.MethodsDuring a 5-year period, we performed 41 intraarticular resections with endoprosthetic reconstructions for malignancies in the proximal humerus meeting specified criteria to generate similarity in the study groups. Twelve patients (29%) were lost to followup before 24 months, leaving 29 patients available for review at a mean of 45 months (range, 24–70 months). This retrospective study compared 14 patients with soft tissue reconstruction that included synthetic mesh with 15 patients with soft tissue reconstruction without the use of synthetic mesh. The choice was made during consultation between the patient and surgeon, after reviewing the perceived advantages and disadvantages of each approach. A tumor band (ligament advanced reinforcement system) was used as synthetic mesh and wrapped around the prosthesis of the proximal humerus for soft tissue reconstruction in the reconstruction-with-mesh group. Study endpoints included the Musculoskeletal Tumor Society (MSTS) function scores, American Shoulder and Elbow Surgeons (ASES) score, shoulder ROM, and proximal migration of the humeral prosthesis.ResultsThe mean MSTS score for patients without synthetic mesh reconstruction was 20 ± 3 points (66%), whereas for patients with synthetic mesh reconstruction, the mean score was 24 ± 2 points (79%; p = 0.001). Patients with synthetic mesh reconstruction had a higher mean total ASES score (85 ± 1.1 points versus 72 ±1.7 points; p = 0.025), and better function for activities of daily living. They also had better ROM on mean active forward flexion (p = 0.020), abduction (p < 0.001), and external rotation (p < 0.001) than patients without synthetic mesh reconstruction. Proximal migration of the prosthesis was observed in five of 15 of patients in the group without synthetic mesh reconstruction and in none of those treated with synthetic mesh (p = 0.042).ConclusionsPatients with intraarticular resection and endoprosthetic replacement of the proximal humerus with reconstruction that included synthetic mesh had better shoulder function and ROM, and more stable joints than patients who had reconstruction without synthetic mesh. This result supports prior observations by others and it remains to be shown whether use of the ligament advanced reconstruction system is superior to other types of mesh or other types of reconstructions. Further investigation is needed but our results indicate that using mesh should be considered for patients with tumor resection and endoprosthetic replacement of the proximal humerus.
Level of Evidence
Level III, therapeutic study. 相似文献995.
996.
We performed a 2-year follow-up survey of 523 patients with peripheral nerve injuries caused by the earthquake in Wenchuan, Sichuan Province, China. Nerve injuries were classified into three types: type I injuries were nerve transection injuries, type II injuries were nerve compression injuries, and type III injuries displayed no direct neurological dysfunction due to trauma. In this study, 31 patients had type I injuries involving 41 nerves, 419 had type II injuries involving 823 nerves, and 73 had type III injuries involving 150 nerves. Twenty-two patients had open transection nerve injury. The restoration of peripheral nerve function after different treatments was evaluated. Surgical decompression favorably affected nerve recovery. Physiotherapy was effective for type I and type II nerve injuries, but not substantially for type III nerve injury. Pharmacotherapy had little effect on type II or type III nerve injuries. Targeted decompression surgery and physiotherapy contributed to the effective treatment of nerve transection and compression injuries. The Louisiana State University Health Sciences Center score for nerve injury severity declined with increasing duration of being trapped. In the first year after treatment, the Louisiana State University Health Sciences Center score for grades 3 to 5 nerve injury increased by 28.2% to 81.8%. If scores were still poor(0 or 1) after a 1-year period of treatment, further treatment was not effective. 相似文献
997.
Derek H. Tang Daniel C. Malone Terri L. Warholak Jenny Chong Edward P. Armstrong Marion K. Slack Chiu-Hsieh Hsu David M. Labiner 《JOURNAL OF CLINICAL NEUROLOGY》2015,11(3):252-261
Background and Purpose
The purpose of this study was to estimate the incidence and prevalence of epilepsy among an elderly and poor population in the United States.Methods
Arizona Medicaid claims data from January 1, 2008 to December 31, 2010 were used for this analysis. Subjects who were aged ≥65 years and were continuously enrolled in any Arizona Medicaid health plans (eligible to patients with low income) for ≥12 months between January 1, 2008 and December 31, 2009 were considered eligible for inclusion in the study cohort. In addition to meeting the aforementioned criteria, incident and prevalent cases must have had epilepsy-related healthcare claims. Furthermore, incident cases were required to have a 1-year "clean" period immediately preceding the index date. Negative binomial and logistic regression models were used to assess the factors associated with epilepsy incidence and prevalence.Results
The estimated epilepsy incidence and prevalence for this population in 2009 were 7.9 and 19.3 per 1,000 person-years, respectively. The incidence and prevalence rates were significantly higher for patients with comorbid conditions that were potential risk factors for epilepsy and were of younger age than for their non-comorbid and older counterparts (p<0.05). The prevalence rates were significantly higher for non-Hispanic Blacks and male beneficiaries than for non-Hispanic Whites and female beneficiaries, respectively (p<0.05).Conclusions
This patient population had higher epilepsy incidence and prevalence compared with the general US population. These differences may be at least in part attributable to their low socioeconomic status. 相似文献998.
目的 探讨新型彩头输液管在多通道微量泵静脉输注时识别的准确性、效率,降低微量泵用药风险及提高抢救效率.方法 模拟微量泵静脉输注试验,设实验组和对照组,各组1个操作站,各有5台微量泵,2个操作站所用药物一致.对照组采用5根传统微量泵输液管连接注射器与三通,实验组采用新型彩头微量泵输液管连接注射器与三通.结果 对照组受试者完成所有药物与三通一一对应所用时间为(45.2±18.4)s,平均每种药物对应所需时间为(9.0±3.7)s,实验组用时分别为(15.7±3.1)s和(3.1±0.7)s;对照组91.95%受试者将药物与三通对应操作完全准确,实验组为99.66%,两组比较,差异有统计学意义(均P<0.01).结论 新型彩头输液管能提高工作效率,保证微量泵用药的安全性和准确性,有助于降低医疗风险和提高抢救效率;且操作方便快捷. 相似文献
999.
1000.
目的 探讨慢性肾脏病(CKD)患者血清胎盘生长因子(placental growth factor,PLGF)水平及其与左心室结构和功能的关系.方法 选取CKD非透析患者72例,年龄、性别相匹配的健康体检者16例作为对照组.采用酶联免疫吸附法测定血清PLGF浓度,心脏超声评定心脏形态和结构.结果 (1)CKD患者血清PLGF显著高于对照组[3.32(2.97,19.77) ng/L比2.33 (2.27,2.49) ng/L,P<0.01];且随着肾功能的减退,PLGF水平进行性升高(P< 0.05/6).(2)CKD各期患者的室间隔厚度(IVST)和左室后壁厚度(LVPWT)升高,射血分数(EF)下降.(3)CKD患者左心室肥厚组血清PLGF显著高于非左心室肥厚组[19.05 (3.31,21.05) ng/L比2.99 (2.60,3.32) ng/L,P<0.05].PLGF高浓度组左室肥厚发生率显著高于PLGF低浓度组(70%比18%,P< 0.01).(4)相关分析显示PLGF与左心室质量指数、收缩压、舒张压、24 h尿蛋白、血肌酐(Scr)、血尿酸(UA)、血尿素氮(BUN)、甲状旁腺激素(iPTH)、高血压病史呈正相关(P<0.05),与左心室射血分数、血红蛋白(Hb)、血白蛋白(Alb)、肾小球滤过率(eGFR)呈负相关(P<0.01).多元线性逐步回归分析显示,血肌酐、血红蛋白、射血分数、血尿酸是PLGF的独立相关因素(P<0.05).结论 CKD患者血清PLGF显著升高,PLGF与CKD患者心脏结构和功能改变密切相关,其可能参与CKD患者心血管事件的发生. 相似文献