全文获取类型
收费全文 | 286759篇 |
免费 | 24051篇 |
国内免费 | 11132篇 |
专业分类
耳鼻咽喉 | 3180篇 |
儿科学 | 6005篇 |
妇产科学 | 3540篇 |
基础医学 | 37163篇 |
口腔科学 | 8068篇 |
临床医学 | 27349篇 |
内科学 | 40697篇 |
皮肤病学 | 6555篇 |
神经病学 | 15672篇 |
特种医学 | 7571篇 |
外国民族医学 | 152篇 |
外科学 | 26258篇 |
综合类 | 43185篇 |
现状与发展 | 66篇 |
一般理论 | 2篇 |
预防医学 | 9772篇 |
眼科学 | 5459篇 |
药学 | 22492篇 |
102篇 | |
中国医学 | 15931篇 |
肿瘤学 | 42723篇 |
出版年
2024年 | 640篇 |
2023年 | 4514篇 |
2022年 | 8099篇 |
2021年 | 11217篇 |
2020年 | 10229篇 |
2019年 | 9532篇 |
2018年 | 9482篇 |
2017年 | 10241篇 |
2016年 | 10810篇 |
2015年 | 11434篇 |
2014年 | 18331篇 |
2013年 | 21579篇 |
2012年 | 16389篇 |
2011年 | 17997篇 |
2010年 | 14952篇 |
2009年 | 14061篇 |
2008年 | 14387篇 |
2007年 | 15032篇 |
2006年 | 13555篇 |
2005年 | 12295篇 |
2004年 | 10558篇 |
2003年 | 9288篇 |
2002年 | 7625篇 |
2001年 | 6621篇 |
2000年 | 5500篇 |
1999年 | 4706篇 |
1998年 | 4271篇 |
1997年 | 3790篇 |
1996年 | 3337篇 |
1995年 | 2932篇 |
1994年 | 2512篇 |
1993年 | 2051篇 |
1992年 | 1700篇 |
1991年 | 1595篇 |
1990年 | 1265篇 |
1989年 | 1159篇 |
1988年 | 1097篇 |
1987年 | 896篇 |
1986年 | 799篇 |
1985年 | 1026篇 |
1984年 | 908篇 |
1983年 | 646篇 |
1982年 | 665篇 |
1981年 | 559篇 |
1980年 | 462篇 |
1979年 | 367篇 |
1978年 | 241篇 |
1977年 | 179篇 |
1976年 | 151篇 |
1975年 | 70篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
《Actas urologicas espa?olas》2022,46(7):397-406
PurposeAssess multiparametric-MRI (mp-MRI) diagnostic accuracy in the detection of local recurrence of prostate cancer (PCa) after radical prostatectomy (PR) and before radiation therapy (RT).Materials and methodsA total of 188 patients underwent 1.5-T mp-MRI after RP before RT. Patients were divided into 2 groups: with biochemical recurrence (group A) and without but with high risk of local recurrence (group B). Continuous variables were compared between 2 groups using Student-t test; categoric variables were analyzed using Pearson chi-square. ROC analysis was performed considering PSA before RT, ISUP, pT and pN as grouping variables.ResultsPCa recurrence (reduction of PSA levels after RT) was 89.8% in group A and 80.3% in group B. Comparing patients with and without PCa recurrence, there was a significant difference in PSA values before RT for group A and for PSA values before RT and after RT for group B. In group A, there was a significant correlation between PSA before RT and diameter of recurrence and between PSA before RT and time spent before recurrence. The mp-MRI diagnostic accuracy in detecting PCa local recurrence after RP is of 62.2% in group A and 38% in group B. Diffusion weighted imaging is the most specific MRI-sequence and dynamic contrast enhanced the most sensitive. For PSA = 0.5 ng/ml, the AUC decreases while sensitivity and accuracy increase for each MRI-sequence. For PSA = 0.9 ng/ml, dynamic contrast enhanced-AUC increases significantly.Conclusionmp-MRI should always be performed before RT when a recurrence is suspected. New scenarios can be opened considering the role of diffusion weighted imaging for PSA ≤ 0.5 ng/ml. 相似文献
42.
《Journal of endodontics》2020,46(10):1455-1464
IntroductionThe aim of this study was to investigate whether mineral trioxide aggregate (MTA) can be modified with caffeic acid (CA) to form caffeic acid/mineral trioxide aggregate (CAMTA) cement and to evaluate its physicochemical and biological properties as well as its capability in immune suppression and angiogenesis.MethodsMTA was immersed in trishydroxymethyl aminomethane buffer with CA to allow coating onto MTA powders. X-ray diffractometry and tensile stress-strain tests were conducted to assess for physical characteristics of CAMTA and to evaluate for successful modification of MTA. Then, the CAMTA cement was immersed in simulated body fluid to evaluate its hydroxyapatite formation capabilities and Si release profiles. In addition, RAW 264.7 cells and human dental pulp stem cells were used to evaluate CAMTA’s immunosuppressive capabilities and cell responses, respectively. hDPSCs were also used to assess CAMTA’s angiogenic capabilities.ResultsThe X-ray diffractometry results showed that CA can be successfully coated onto MTA without disrupting or losing MTA’s original structural properties, thus allowing us to retain the initial advantages of MTA. CAMTA was shown to have higher mechanical properties compared with MTA and had rougher pitted surfaces, which were hypothesized to lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. In addition, it was found that CAMTA was able to enhance hydroxyapatite formation and immunosuppressive capabilities compared with MTA.ConclusionsCAMTA cements were found to have improved physicochemical and biological characteristics compared with their counterpart. In addition, CAMTA cements had enhanced odontogenic, angiogenic, and immunosuppressive properties compared with MTA. All of the results of this study proved that CAMTA cements could be a biomaterial for future clinical applications and tissue engineering use. 相似文献
43.
《Journal of endodontics》2020,46(9):1317-1322
IntroductionThe purpose of this study is to evaluate the amount of residual obturation material of retroinstrumented surgically resected roots using controlled memory files and to evaluate the incidence of adverse treatment outcomes.MethodsThirty maxillary anterior teeth in human cadavers were selected, and nonsurgical root canal treatment was performed on these teeth. A standardized 4-mm osteotomy and a 3-mm root resection with as close to 0° bevel as possible were made on each tooth. A microsurgical diamond tip was used to create a 1- to 2-mm starting point for each retropreparation. A 25/06 and 30/06 VTaper 2H were bent at about 90° angle to mimic the clinical and anatomic restrictions and used to create a retropreparation to a depth of 14 mm. Micro–computed tomography scans were taken and analyzed for volume and percentage of residual obturation material at 5 and 10 mm. In addition, the incidences of instrument separation and crack and ledge formation in the teeth were recorded.ResultsThe median volume of residual obturation at 5 and 10 mm was 0.18 mm3 (interquartile range, 0.36 mm3) and 1.97 mm3 (interquartile range, 1.99 mm3), respectively. The overall incidence of file separation during retropreparation was 13.33% (4/30). Among the cases analyzed with micro–computed tomography, none showed crack or ledge formation.ConclusionsRetroinstrumentation of surgically resected roots using controlled memory files cleans the canal effectively with relatively low adverse treatment outcomes. Although this novel technique is limited in application, it is a safe and effective way to achieve a deep, clean retropreparation. 相似文献
44.
Yesim Aydinok 《ISBT科学丛刊》2020,15(1):102-109
Lifetime red cell concentrate (RCC) transfusions still account for significant iron overload‐related morbidity and mortality despite chelation therapy in thalassaemia. The cumulative risk of transfusion‐transmitted infections is substantial for thalassaemia patients. Pathogen reduction technologies for RCC may imply a proactive approach against new/re‐emerging pathogens and may be an ultimate safeguard for transfusion safety in the developing countries. Red cell alloimmunization may become a significant clinical challenge in thalassaemia. The availability of high‐throughput molecular blood group antigen typing in the donors may allow perfect match transfusion, beyond ABO‐D and CEK antigen‐matched transfusions. Allogeneic stem cell transplantation (A‐SCT) is the only available curative therapy in thalassaemia, but carries a substantial risk of serious adverse events and mortality. Gene addition therapy for correction of the α‐globin chain imbalance overcomes the problems of donor availability and immunological complications of A‐SCT. Gene editing by either gene disruption or correction emerged as a potential alternative to gene addition therapy in beta‐thalassaemia. A new era of novel therapeutics targeting α/β imbalance, ineffective erythropoiesis or iron dysregulation is unfolding in thalassaemia management, and a number of those now have agents in preclinical and clinical development. Hydroxyurea (HU) may improve globin chain imbalance and be beneficial for reducing or omitting transfusion requirement. Ruxolitinib has allowed steady decrease in spleen volume that may serve for avoiding splenectomy in beta‐thalassaemia. Luspatercept may restore normal erythroid differentiation and improve anaemia. Hepcidin mimetics or TMPRSS6 inhibitors may modulate ineffective erythropoiesis by iron restriction and improve anaemia and organ iron loading. 相似文献
45.
Anuj Shrestha Zeeshan Jawa Kathryn L. Koch Amy B. Rankin Qun Xiang Anand Padmanabhan Matthew S. Karafin Joshua J. Field 《Journal of clinical apheresis》2015,30(6):353-358
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
46.
Stephanie Kay Kolar 《Addiction Research & Theory》2016,24(1):25-31
Aims: Relapse rates among cigarette smokers are high. Few studies have examined time-to-relapse using survival analysis in racially/ethnically diverse smokers and initial abstinence criteria have been inconsistent or unspecified. This study compared survival curves using two common definitions of initial abstinence. We hypothesized greater relapse rates among participants abstinent for only 24 hours (h) at the end-of-therapy (EOT) compared with 7 days. Methods: Adult smokers (59% Black, 22% Hispanic and 17% White) received 8-sessions of group cognitive behavioural therapy (CBT) plus transdermal nicotine patches and were assessed monthly up to 12 months post-EOT. Participants reporting abstinence (7-day point prevalence abstinence [ppa] or 24-h ppa) at the EOT were included in Kaplan–Meier curves. Results: Of 301 participants, 120 (40%) reported 7-day ppa at the EOT and an additional 29 (10%) reported 24-h ppa only. Over the 12-month follow-up period, nearly 50% remained abstinent. Of those who resumed smoking, most relapses occurred within the first three months. Survival curves indicated that median survival was 207 and 225 days for 7-day and 24-h definitions of abstinence, respectively. The difference in time-to-relapse between participants abstinent for 24?h at the EOT versus 7-days was not significant (p?=?0.14). Conclusions: Operationalization of initial abstinence is important for relapse analyses and comparisons of survival curves across samples. Participants reported high rates of abstinence and relapse rates were relatively low. Contrary to expectations, 24-h ppa at the EOT was not associated with greater relapse than 7-day abstinence. This suggests either measure may be utilized in relapse prevention research in racially/ethnically diverse treatment-seekers. 相似文献
47.
我国属胃癌高发国家,且以进展期胃癌为主。以手术和化疗为主的多学科治疗无法有效改善晚期胃癌患者的预后。近年来,免疫检查点抑制剂类药物的疗效在诸多癌症中得到了证实,因此,该类药物在胃癌中的治疗效果也受到了广泛的关注。本文对近年来的相关研究成果进行综述,全面介绍了免疫检查点抑制剂类药物在胃癌治疗中的临床应用情况、联合用药情况以及不良反应。对于其他治疗均失败的晚期胃癌患者,PD-1抑制剂是一个可行的治疗选项,其代表药物派姆单抗是目前唯一被美国食品药品监督管理局批准应用于胃癌治疗的免疫抑制剂类药物,而我国国家食品药品监督管理总局尚未批准任何此类药物应用于胃癌的临床治疗。如何进一步提高治疗的客观缓解率,将会是后续临床和基础研究的一大焦点。 相似文献
48.
49.
50.