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   59500篇
  免费   2843篇
  国内免费   535篇
耳鼻咽喉   357篇
儿科学   840篇
妇产科学   1540篇
基础医学   7947篇
口腔科学   1807篇
临床医学   7228篇
内科学   7727篇
皮肤病学   684篇
神经病学   5102篇
特种医学   4710篇
外国民族医学   2篇
外科学   6725篇
综合类   2112篇
现状与发展   8篇
一般理论   7篇
预防医学   5614篇
眼科学   800篇
药学   4920篇
  16篇
中国医学   971篇
肿瘤学   3761篇
  2024年   102篇
  2023年   3463篇
  2022年   4946篇
  2021年   4380篇
  2020年   4631篇
  2019年   2717篇
  2018年   2308篇
  2017年   2912篇
  2016年   2839篇
  2015年   2811篇
  2014年   5084篇
  2013年   3186篇
  2012年   2309篇
  2011年   1789篇
  2010年   3155篇
  2009年   2963篇
  2008年   1057篇
  2007年   1400篇
  2006年   1136篇
  2005年   795篇
  2004年   695篇
  2003年   768篇
  2002年   720篇
  2001年   719篇
  2000年   502篇
  1999年   730篇
  1998年   761篇
  1997年   571篇
  1996年   687篇
  1995年   609篇
  1994年   413篇
  1993年   340篇
  1992年   226篇
  1991年   216篇
  1990年   247篇
  1989年   172篇
  1988年   206篇
  1987年   22篇
  1986年   21篇
  1985年   25篇
  1984年   38篇
  1983年   29篇
  1982年   21篇
  1981年   19篇
  1980年   16篇
  1979年   21篇
  1978年   26篇
  1977年   15篇
  1976年   18篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
The effect of tuna eyeball oil (TEO) on lipopolysaccharide (LPS)-induced inflammation in macrophage cells was investigated. TEO had no cytotoxicity in cell viability as compared to the control in LPS induced RAW 264.7 cells. TEO reduced the levels of NO and pro-inflammatory cytokines by up to 50% in a dose-dependent manner. The expression of NF-κB and MAPKs as well as iNOS and COX-2 proteins was reduced by TEO, which suggests that its anti-inflammatory activity is related to the suppression of the NF-κB and MAPK signaling pathways. The rate of formation of ear edema was reduced compared to that in the control at the highest dose tested. In an acute toxicity test, no mice were killed by TEO doses of up to 5000 mg/kg body weight during the two week observation period. These results suggested that TEO may have a significant effect on inflammatory factors and be a potential anti-inflammatory therapeutic.  相似文献   
92.
BackgroundIKZF1 deletions are associated with adverse outcomes in B-cell acute lymphoblastic leukemia (B-ALL). We assessed the prevalence and clinical impact of functional subtypes of IKZF1 deletions in pediatric BCR–ABL1-negative B-ALL. Patients andMethodsThis retrospective study of IKZF1 deletions was done in cases of pediatric BCR–ABL1-negative B-ALL. The genomic DNA of cases, over a 53-month period, was analyzed using multiplex ligation-dependent probe amplification and multiplex fluorescent polymerase chain reaction. The deletions were divided into functional subgroups: (1) loss-of-function/haploinsufficiency, (2) dominant-negative, and (3) a combination of both types of deletion. The post-induction remission status, event-free survival (EFS), and overall survival (OS) were noted.ResultsOut of 320 cases, 47 (14.7%) had IKZF1 deletions. Thirty-six of the 47 (77%) had loss-of-function deletions, 10 (21%) had dominant-negative deletions, and one (2%) had a combination of both types. The post-induction remission rates in cases with loss-of-function deletions (22/30, 73%; P = .060) and dominant-negative deletions (4/5, 80%; P = .517) were lower compared with those without deletions (215/248, 86.7%). These cases also had worse median EFS: 21.1 months (P = .006) for loss-of-function and 15.4 months (P = .156) for dominant-negative deletions, compared with 46.4 months in cases without IKZF1 deletions. They also had worse median OS: 23.4 months (P = .012) for loss-of-function deletions and 15.7 months (P = .233) for dominant-negative deletions, compared with median not reached in cases without IKZF1 deletions.ConclusionThe IKZF1 deletions were seen in 14.7% of BCR–ABL1-negative pediatric B-ALL. Most of these deletions (77%) were loss-of-function type. The cases with loss-of-function deletions had lower remission rates and poor EFS and OS compared with cases without IKZF1 deletions. A similar trend of poor outcome was seen in the few cases with dominant-negative IKZF1 deletions.  相似文献   
93.
94.
95.
96.
BackgroundThe objective of this study was to validate and update the Amsterdam prediction model including tumor grade, lymph node ratio, margin status and adjuvant therapy, for prediction of overall survival (OS) after pancreatoduodenectomy for pancreatic cancer.MethodsWe included consecutive patients who underwent pancreatoduodenectomy for pancreatic cancer between 2000 and 2017 at 11 tertiary centers in 8 countries (USA, UK, Germany, Italy, Sweden, the Netherlands, Korea, Australia). Model performance for prediction of OS was evaluated by calibration statistics and Uno's C-statistic for discrimination. Validation followed the TRIPOD statement.ResultsOverall, 3081 patients (53% male, median age 66 years) were included with a median OS of 24 months, of whom 38% had N2 disease and 77% received adjuvant chemotherapy. Predictions of 3-year OS were fairly similar to observed OS with a calibration slope of 0.72. Statistical updating of the model resulted in an increase of the C-statistic from 0.63 to 0.65 (95% CI 0.64–0.65), ranging from 0.62 to 0.67 across different countries. The area under the curve for the prediction of 3-year OS was 0.71 after updating. Median OS was 36, 25 and 15 months for the low, intermediate and high risk group, respectively (P < 0.001).ConclusionsThis large international study validated and updated the Amsterdam model for survival prediction after pancreatoduodenectomy for pancreatic cancer. The model incorporates readily available variables with a fairly accurate model performance and robustness across different countries, while novel markers may be added in the future. The risk groups and web-based calculator www.pancreascalculator.com may facilitate use in daily practice and future trials.  相似文献   
97.
98.
目的探讨体外转染细胞周期素A2(Cyclin A2)基因对原代大鼠心肌细胞增殖的影响,为心脏再生提供细胞学依据。方法 SD乳鼠12只,分离、培养、鉴定原代乳鼠心肌细胞并分为3组,实验组:转染带有强化绿色荧光蛋白(GFP)和Cyclin A2基因的重组腺病毒(Ad-Cyclin A2-GFP);空病毒组:转染不含目的基因带有GFP的重组腺病毒(Ad-Null-GFP);阴性对照组:未做转染处理,仅加入等量的培养基。利用GFP示踪技术,评估原代心肌细胞转染效率;转染后的细胞继续体外培养3~5d,利用免疫荧光技术分别检测Cyclin A2、磷酸化组蛋白H3(H3P)、心肌肌钙蛋白-T(c Tn T)。结果 1.荧光GFP示踪表明原代心肌细胞的转染效率高达(97±0.74)%;2.免疫荧光标记显示,空病毒组和对照组结果相似;心肌细胞特异性标记蛋白c Tn T分布于细胞质,原代心肌细胞纯度高达(95±0.62)%;心肌细胞Cyclin A2主要在胞核内聚集,少数分布于细胞质。H3P为核蛋白在细胞核内分布。3.转染Cyclin A2后,实验组H3P阳性率明显高于空病毒组和对照组,差异具有统计学意义(P0.05);实验组可见大量多核细胞,以双核为主,伴少量3核细胞。结论腺病毒作为转染载体对原代心肌细胞有很好的侵染效率;Cyclin A2超表达促进原代心肌细胞形成双核。  相似文献   
99.
《Injury》2022,53(12):3962-3969
IntroductionEducators are exposed to several work-related hazards. Evidence suggests musculoskeletal pain, psychological distress, and student-inflicted violence-related injuries are common. However, there is little evidence on the burden of workplace injury among Australian educators.AimTo compare incidence of injury claims and duration of compensated time off work between educators and non-educators, and associated factors.MethodsRetrospective cohort study of 1,559,676 Australian workers’ compensation claims, including 84,915 educator claims, lodged between July 2009 to June 2015, from the National Dataset for Compensation-based Statistics. Cases were included if aged 18+ years and working in the education sector less than 100 h per week. Negative binomial regression models estimated the relative risk of making a compensation claim and survival analyses calculated disability duration within educators by sex, age, injury type and mechanism, socioeconomic area, remoteness, and jurisdiction.ResultsCompared to non-educators, educators had lower rates of injury claims and shorter disability durations. However, educators had a higher rate of claims for mental health conditions and assault, with the highest risk being among those in special education and education aides. Among educators, injury claim rates were highest among special educators, education aides, and secondary educators.Discussion and ConclusionThough surveys indicate Australians in the education sector have higher incidences of work-related injuries, this study found lower incidence of injury claims and shorter disability durations than others. Educators’ injury-reporting and absenteeism behaviors may be constrained by ethical, social, and administrative attitudes. Educators had higher rates of claims for mental health and assault-related injury, particularly special educators, and education aides, which suggests a need for targeted prevention efforts.  相似文献   
100.
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