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   75099篇
  免费   5657篇
  国内免费   2497篇
耳鼻咽喉   433篇
儿科学   1568篇
妇产科学   1077篇
基础医学   11044篇
口腔科学   1153篇
临床医学   5704篇
内科学   11261篇
皮肤病学   1275篇
神经病学   5490篇
特种医学   1003篇
外国民族医学   19篇
外科学   5244篇
综合类   8841篇
现状与发展   12篇
预防医学   5449篇
眼科学   1242篇
药学   13811篇
  16篇
中国医学   4293篇
肿瘤学   4318篇
  2023年   1051篇
  2022年   1317篇
  2021年   2328篇
  2020年   2529篇
  2019年   2862篇
  2018年   2758篇
  2017年   2620篇
  2016年   2643篇
  2015年   2677篇
  2014年   4702篇
  2013年   6322篇
  2012年   5142篇
  2011年   5549篇
  2010年   4539篇
  2009年   3807篇
  2008年   3425篇
  2007年   2903篇
  2006年   2444篇
  2005年   2153篇
  2004年   1877篇
  2003年   1681篇
  2002年   1331篇
  2001年   1149篇
  2000年   850篇
  1999年   841篇
  1998年   670篇
  1997年   626篇
  1996年   538篇
  1995年   512篇
  1994年   455篇
  1993年   426篇
  1992年   387篇
  1991年   364篇
  1990年   323篇
  1989年   268篇
  1988年   259篇
  1987年   192篇
  1985年   887篇
  1984年   1158篇
  1983年   905篇
  1982年   1041篇
  1981年   948篇
  1980年   730篇
  1979年   664篇
  1978年   471篇
  1977年   387篇
  1976年   432篇
  1975年   337篇
  1974年   214篇
  1973年   225篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Bleomycin is a well-recognized antineoplastic drug. However, pulmonary fibrosis (PF) is considered to be the principal drawback that greatly limits its use. Here, we sought to investigate ability of the neurokinin receptor 1 blocker, aprepitant, to prevent PF caused by bleomycin. Male adult Wistar rat groups were given a single intratracheal injection of bleomycin, either alone or in combination with aprepitant therapy for 3 or 14 days. Collagen deposition and a rise in transforming growth factor beta (TGF-β) immunoreactivity in lung tissue serve as evidence of bleomycin-induced PF. The serum levels of lactate dehydrogenase, alkaline phosphatase, and total antioxidant improved after aprepitant therapy.Additionally, it reduced the protein expressions of interferon alpha, tumor necrosis factor alpha, and lung lipid peroxidation. Moreover, aprepitant treatment led to an increase in the antioxidant indices glutathione, glutathione peroxidase, and catalase. Aprepitant is postulated to protect against bleomycin-induced PF by decreasing TGF-β, phosphorylating Smad3, and increasing interleukin 37, an anti-fibrotic cytokine, and G Protein-coupled Receptor Kinase 2. Aprepitant for 14 days considerably exceeded aprepitant for 3 days in terms of improving lung damage and having an anti-fibrotic impact. In conclusion, aprepitant treatment for 14 days may be used as an adjuvant to bleomycin therapy to prevent PF, mostly through inhibiting the TGF-/p-Smad3 fibrotic pathway.  相似文献   
72.
《Vaccine》2022,40(43):6255-6270
Swine influenza A virus (swIAV) infections in pig populations cause considerable morbidity and economic losses. Frequent reverse zoonotic incursions of human IAV boost reassortment opportunities with authentic porcine and avian-like IAV in swine herds potentially enhancing zoonotic and even pre-pandemic potential. Vaccination using adjuvanted inactivated full virus vaccines is frequently used in attempting control of swIAV infections. Accelerated antigenic drift of swIAV in large swine holdings and interference of maternal antibodies with vaccine in piglets can compromise these efforts. Potentially more efficacious modified live-attenuated vaccines (MLVs) bear the risk of reversion of MLV to virulence. Here we evaluated new MLV candidates based on cold-passaged swIAV or on reassortment-incompetent bat-IAV-swIAV chimeric viruses. Serial cold-passaging of various swIAV subtypes did not yield unambiguously temperature-sensitive mutants although safety studies in mice and pigs suggested some degree of attenuation. Chimeric bat-swIAV expressing the hemagglutinin and neuraminidase of an avian-like H1N1, in contrast, proved to be safe in mice and pigs, and a single nasal inoculation induced protective immunity against homologous challenge in pigs. Reassortant-incompetent chimeric bat-swIAV vaccines could aid in reducing the amount of swIAV circulating in pig populations, thereby increasing animal welfare, limiting economic losses and lowering the risk of zoonotic swIAV transmission.  相似文献   
73.
74.
This article begins with an overview of the knowledge translation (KT) process, introduces commonly used KT terms and the Aware-Adopt-Adapt (A3) KT map. The A3 was created by a nurse practitioner (NP) for practitioners and NP students to provide a map for those who wish to move existing knowledge to practice, yet do not know where to start or do not have the time to take a deeper dive into specific KT theories.  相似文献   
75.
《Clinical breast cancer》2022,22(6):507-514
Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC.  相似文献   
76.
《Vaccine》2022,40(12):1872-1878
BackgroundThe MenB-FHbp vaccine (Trumenba®) is licensed in various countries for the prevention of meningococcal serogroup B disease in individuals ≥ 10 years of age. The clinical development program included 11 completed trials where, in each trial, MenB-FHbp had an acceptable safety profile after a primary vaccination series was administered to individuals 10–65 years of age. However, the detection of potential rare events was limited because of individual clinical trial size. The current safety analysis evaluates pooled reactogenicity and other adverse events (AEs) reported in these trials to identify new safety signals not detectable in individual trials.MethodsEleven trials contributed safety data, of which 10 recorded local and systemic reactogenicity events; 8 of the trials were controlled, and reactogenicity data were pooled for 7 of these 8 trials. Additional AE evaluations included immediate AEs (IAEs), medically attended AEs (MAEs), serious AEs (SAEs), newly diagnosed chronic medical conditions (NDCMCs), and autoimmune or neuroinflammatory conditions.ResultsLocal and systemic reactions were more frequent in the MenB-FHbp group (n = 15,294) compared with controls (n = 5509), although most reactions were transient and mild to moderate in severity. Frequencies of IAEs, SAEs, MAEs, NDCMCs, and autoimmune or neuroinflammatory conditions were similar between the MenB-FHbp and control groups.ConclusionsMenB-FHbp demonstrated a favorable safety and tolerability profile in the clinical development program of > 15,000 vaccine recipients ≥ 10 years of age. No new safety signals were identified in the pooled analysis compared with data from the individual trials. Continued postmarketing safety surveillance is important for the identification of rare events.Clinicaltrials.gov: NCT01299480; NCT000808028; NCT00879814; NCT00780806; NCT01352845; NCT01352793; NCT01461993; NCT01323270; NCT01830855; NCT01461980; NCT01768117.  相似文献   
77.
《Survey of ophthalmology》2022,67(6):1647-1684
Managing pediatric corneal disorders is challenging as the prognosis of pediatric keratoplasty depends on several factors. Advancements in the genetic basis of congenital corneal diseases and investigations in congenital corneal conditions provide a better understanding of pediatric corneal conditions. Surgeons performing keratoplasty in children now have a choice of various techniques. Evolving surgical techniques of anterior lamellar and endothelial keratoplasties have expanded the management interventions in these pediatric corneal morbidity conditions; however, considerable concerns still exist in association with corneal transplantation in infants and children. Outcomes in pediatric keratoplasty depend upon the preoperative indications, the timing of surgical intervention, intraoperative and postoperative factors including the patient/care givers’ compliance. Factors such as low scleral rigidity, higher rate of graft failure, need for frequent examinations under anesthesia, and difficulty in optimal visual acuity assessment still remain a considerable challenge in pediatric scenarios. In children, deprivation amblyopia as a result of the corneal opacification can adversely affect visual development, causing dense amblyopia. Outcomes to surgical interventions for management of corneal opacification in children are further compromised by the preexisting amblyopia apart from the concerns of refractive outcome of the graft. Graft rejection, graft infection, amblyopia, and glaucoma continue to be serious concerns. In recent years both anterior and posterior lamellar keratoplasty techniques are being increasingly performed in pediatric eyes, which offer advantages in the form of lower risk of graft rejection. The timing of surgery, careful case selection, cautious intraoperative approach, and optimal postoperative management can improve the anatomical and functional outcome in difficult cases.  相似文献   
78.
目的探讨解偶联蛋白1(UCP1)基因多态性与2型糖尿病(T2DM)心脑血管并发症的相关性。方法选取2019年7月—2020年7月住院治疗的T2DM 440例,根据有无心脑血管并发症分为观察组(T2DM合并心脑血管并发症)221例和对照组(单纯T2DM)219例。比较两组一般资料,UCP1在rs45539933、rs10011540及rs1800592位点的基因型分布与等位基因频率;通过多因素Logistic回归分析评估T2DM发生心脑血管事件的危险因素。结果观察组病程长于对照组,糖化血红蛋白水平高于对照组,而血清高密度脂蛋白胆固醇水平低于对照组(P<0.01)。观察组C/C基因型分布及C碱基频率均高于对照组(P<0.05)。C/C基因型是T2DM患者发生心脑血管并发症的危险因素(P<0.05)。结论UCP1基因多态性与T2DM心脑血管并发症的发生显著相关。  相似文献   
79.
80.
BackgroundThis study compared bone union progression using highly porous (80% porosity) β-tricalcium phosphate (β-TCP) granules or allogeneic bone chips in the gap created by medial opening-wedge high tibial osteotomy (MOWHTO).MethodsThe study population consisted of 54 patients who received MOWHTO with locking plate fixation: 27 patients using highly porous β-TCP granules, and 27 age- and sex-matched patients using allogeneic bone chips. Bone union progression was evaluated 1, 3, 6, and 12 months postoperatively. The presence of radiographic sclerosis at the osteotomy margin was also assessed.ResultsAmong all patients, the highest degree of bone union observed 12 months postoperatively was grade 4. As postoperative time passed, bone union progression of highly porous β-TCP granules increased linearly and was statistically significant compared with that of cancellous allogeneic bone chips (P = 0.014). The presence of radiographic sclerosis at the osteotomy margin was significantly less common in the β-TCP group than in the allograft group (P = 0.003) and was the strongest predictor of delayed progress of bone union (odds ratio = 6.16, P = 0.006).ConclusionsPatients who underwent MOWHTO using highly porous β-TCP granules had faster new bone remodeling, less radiographic sclerosis at the osteotomy margin, and no inferior clinical outcome compared with allogeneic bone chips, as determined at the 1-year follow up. The presence of radiographic sclerosis at the osteotomy margin in patients undergoing MOWHTO using allogeneic bone or synthetic bone substitute may indicate delayed progress of bone union.  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