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   153976篇
  免费   11503篇
  国内免费   4102篇
耳鼻咽喉   1103篇
儿科学   2695篇
妇产科学   2058篇
基础医学   8491篇
口腔科学   3016篇
临床医学   17387篇
内科学   21512篇
皮肤病学   2786篇
神经病学   7406篇
特种医学   4416篇
外国民族医学   42篇
外科学   13451篇
综合类   21993篇
现状与发展   23篇
一般理论   2篇
预防医学   9066篇
眼科学   2233篇
药学   20560篇
  90篇
中国医学   12344篇
肿瘤学   18907篇
  2024年   240篇
  2023年   2486篇
  2022年   4038篇
  2021年   6509篇
  2020年   6017篇
  2019年   5428篇
  2018年   5216篇
  2017年   5695篇
  2016年   6057篇
  2015年   5925篇
  2014年   11164篇
  2013年   14092篇
  2012年   9481篇
  2011年   10234篇
  2010年   8222篇
  2009年   7555篇
  2008年   7455篇
  2007年   7672篇
  2006年   6855篇
  2005年   6022篇
  2004年   4884篇
  2003年   4323篇
  2002年   3478篇
  2001年   3089篇
  2000年   2609篇
  1999年   2129篇
  1998年   1695篇
  1997年   1453篇
  1996年   1196篇
  1995年   1085篇
  1994年   920篇
  1993年   708篇
  1992年   640篇
  1991年   552篇
  1990年   486篇
  1989年   427篇
  1988年   432篇
  1987年   367篇
  1986年   312篇
  1985年   376篇
  1984年   355篇
  1983年   238篇
  1982年   238篇
  1981年   219篇
  1980年   198篇
  1979年   177篇
  1978年   124篇
  1977年   96篇
  1976年   112篇
  1975年   100篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
91.
的 了解血流感染肺炎克雷伯菌中CRISPR-Cas系统的分布特征并分析其与毒力基因和耐药的关系。方法 收集非重复血流感染肺炎克雷伯菌248株,使用Vitek2-Compact全自动微生物分析系统进行菌株鉴定及药物敏感性分析,PCR检测CRISPR-Cas系统3个相关基因(CRISPR1、CRISPR2和cas1)、筛查6种常见高毒力荚膜血清型(K1、K2、K5、 K20、K54和K57)、12种毒力基因及检测13种耐药基因,用χ2检验比较携带有CRISPR-Cas系统菌株与不携带CRISPR-Cas系统菌株毒力及耐药差异。结果 CRISPR-Cas系统的检出率为29.8%(74/248);K1型是携带CRISPR-Cas系统肺炎克雷伯菌的主要荚膜血清型,占 28.4%(21/74);除kpn基因外,携带CRISPR-Cas系统菌株的毒力基因检出率均大于不携带CRISPR-Cas系统菌株,其中7种差异有统计学意义;除对氨苄西林耐药率达100%外,携带有CRISPR-Cas系统菌株的其他抗菌药物耐药率均小于不携带有CRISPR-Cas系统菌株,其中13种差异有统计学意义;携带CRISPR-Cas系统菌株的耐药基因阳性率小于不携带CRISPR-Cas系统的菌株,且blaKPC、blaSHV、qnrS基因差异有统计学意义。结论 高毒力荚膜血清型肺炎克雷伯菌中主要为K1型携带CRISPR-Cas系统,携带CRISPR-Cas系统的肺炎克雷伯菌相对于不携带CRISPR-Cas系统菌株的毒力基因阳性率高,耐药率低,耐药基因的阳性率低。CRISPR-Cas系统可能能降低耐药基因在肺炎克雷伯菌中的水平传播,尤其是在K1型肺炎克雷伯菌。  相似文献   
92.
The purpose of this overview was to assess different antibiotic regimens used in orthognathic surgery and to establish an evidence-based protocol so that beneficial and adverse effects can be determined. A comprehensive literature search for systematic reviews and/or meta-analyses was conducted in MEDLINE (PubMed), EMBASE, and the Cochrane Library until March 2020. Grey literature was investigated in Google Scholar, and a manual search was done of references lists. Two meta-analyses and four systematic reviews met the inclusion criteria. The AMSTAR-2-tool was used to ascertain the potential risk of bias in the included studies, which presented moderate to high methodological quality. Lower infection rates were associated with long-term therapies of penicillin, cefazolin-cephalexin, and amoxicillin-clavulanic-acid, with rates varying from 0% - 3.13%. Higher rates were reported in placebo groups (52.6%) and short-term penicillin therapy (60%). Side effects were reported with cefazolin, clindamycin, and penicillin therapies, including nausea, pain, swelling, headache, vomiting, and skin rash. Evidence suggests that long-term antibiotics can reduce the risk of a surgical site infection (SSI) in orthognathic surgery, but there is uncertainty regarding the effects of one dose of antibiotics preoperatively versus short-term antibiotics. In the same way, intravenous penicillin, cefazolin, clindamycin, and amoxicillin-clavulanic acid kept the infection rates associated with bimaxillary procedures under 3.5%.  相似文献   
93.
Microorganisms thrive in well-organized biofilm ecosystems. Biofilm-associated cells typically show increased resistance to antibiotics and contribute significantly to treatment failure. This has prompted investigations aimed at developing advanced and novel antimicrobial approaches that could effectively overcome the shortcomings associated with conventional antibiotic therapy. Studies are ongoing to develop effective curative strategies ranging from the use of peptides, small molecules, nanoparticles to bacteriophages, sonic waves, and light energy targeting various structural and physiological aspects of biofilms. In photodynamic therapy, a light source of a specific wavelength is used to irradiate non-toxic photosensitizers such as tetrapyrroles, synthetic dyes or, naturally occurring compounds to generate reactive oxygen species that can exert a lethal effect on the microbe especially by disrupting the biofilm. The photosensitizer preferentially binds to and accumulates in the microbial cells without causing any damage to the host tissue. Currently, photodynamic therapy is increasingly being used for the treatment of oral caries and dental plaque, chronic wound infections, infected diabetic foot ulcers, cystic fibrosis, chronic sinusitis, implant device-associated infections, etc. This approach is recognized as safe, as it is non-toxic and minimally invasive, making it a reliable, realistic, and promising therapeutic strategy for reducing the microbial burden and biofilm formation in chronic infections. In this review article, we discuss the current and future potential strategies of utilizing photodynamic therapy to extend our ability to impede and eliminate biofilms in various medical conditions.  相似文献   
94.
《Molecular therapy》2022,30(5):1952-1965
  1. Download : Download high-res image (199KB)
  2. Download : Download full-size image
  相似文献   
95.
96.
ObjectivesThe aim of this study was to report 1-year clinical outcomes following commercial transcatheter left atrial appendage occlusion (LAAO) in the United States.BackgroundThe National Cardiovascular Data Registry LAAO Registry was initiated to meet a condition of Medicare coverage and allow the assessment of clinical outcomes. The 1-year rates of thromboembolic events after transcatheter LAAO in such a large cohort of “real-world” patients have not been previously reported.MethodsPatients entered into the National Cardiovascular Data Registry LAAO Registry for a Watchman procedure between January 1, 2016, and December 31, 2018, were included. The primary endpoint was ischemic stroke. Key secondary endpoints included the rate of ischemic stroke or systemic embolism, mortality, and major bleeding. Major bleeding was defined as any bleeding requiring hospitalization, and/or causing a decrease in hemoglobin level > 2g/dL, and/or requiring blood transfusion that was not hemorrhagic stroke. The Kaplan-Meier method was used for 1-year estimates of cumulative event rates.ResultsThe study population consisted of 36,681 patients. The mean age was 76.0 ± 8.1 years, the mean CHA2DS2-VASc score was 4.8 ± 1.5, and the mean HAS-BLED score was 3.0 ± 1.1. Prior stroke was present in 25.5%, clinically relevant bleeding in 69.5%, and intracranial bleeding in 11.9%. Median follow-up was 374 days (IQR: 212-425 days). The Kaplan-Meier–estimated 1-year rate of ischemic stroke was 1.53% (95% CI: 1.39%-1.69%), the rate of ischemic stroke or systemic embolism was 2.19% (95% CI: 2.01%-2.38%), and the rate of mortality was 8.52% (95% CI: 8.19%-8.87%). The 1-year estimated rate of major bleeding was 6.93% (95% CI: 6.65%-7.21%). Most bleeding events occurred between discharge and 45 days following the procedure.ConclusionsThis study characterizes important outcomes in a national cohort of patients undergoing transcatheter LAAO in the United States. Clinicians and patients can integrate these data in shared decision making when considering this therapy.  相似文献   
97.
ObjectiveTo investigate the feasibility of transnasal heated humidified high flow nasal cannula oxygen therapy (HFNC) in the treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with respiratory failure in elderly patients. MethodsA total of 176 elderly patients with AECOPD complicated with respiratory failure who were hospitalized at Peking University Shougang Hospital from December 2016 to January 2022 were enrolled, including 82 patients in an HFNC group and 94 patients in an NPPV group. After treatment, pulse oxygen saturation (SPO2), arterial partial pressure of carbon dioxide (PaCO2), oxygenation index (OI), respiratory rate (RR), heart rate (HR), mean arterial pressure (MAP), comfort score, discharge rate, rate of endotracheal intubation, rate of transfer to intensive care unit (ICU), and mortality were compared between the two groups. The independent sample t-test was used for comparison between the two groups. Statistical data are expressed in percentage or number of cases and the χ2 test was used for their comparisons. ResultsThe SPO2 values at 30 min, 1 h, and 6 h were significantly higher in the HFNC group than in the NPPV group (t=-2.049,-2.618, and -3.314, P=0.043, 0.010, and 0.001, respectively). SPO2 before discharge was significantly lower than that of the NPPV group (t=2.162, P=0.033), but OI at each time point and before discharge had no statistical significance (P>0.05). MAP at 6 h was significantly higher in the HFNC group than in the NPPV group (t=-2.209, P=0.029), but within the normal range. HRs at 2 h and 3 h in the HFNC group were significantly higher than those of the NPPV group (t=-2.199 and -2.336, P=0.030 and 0.021, respectively). There were no significant differences in RR, HR, or MAP between the two groups at other time points and before discharge (P>0.05). There was no significant difference in PaCO2 between the two groups (P>0.05). Comfort score in the HFNC group was significantly higher than that of the NPPV group (t=-46.807, P<0.001). There were no significant differences in discharge rate, ICU transfer rate, endotracheal intubation rate, and mortality between the two groups (P>0.05). ConclusionHFNC is as effective as NPPV in treating elderly patients with AECOPD complicated with type Ⅰ or mild type Ⅱ respiratory failure, and HFNC is more comfortable than NPPV.  相似文献   
98.
Background and aimsObesity and overweight in children are associated with an increased risk of several health issues. The present study aimed to assess the effects of a multi-disciplinary program (including nutrition education using a smartphone game, physical activity, and cognitive behavioral therapy [CBT]) on the management of obesity and overweight in elementary school girls.Methods and resultsSixty-two school girls above the 85th percentile of body mass index (BMI) for age were randomly assigned to two groups. During 10 weeks of study, the intervention group received a multi-disciplinary intervention, including nutrition education using a smartphone game, aerobic exercise, and CBT. The control group received usual traditional nutritional education. Biochemical and metabolic factors were assessed, including fasting blood sugar (FBS), lipid profile, serum leptin, and anthropometric measurements. The Dutch Eating Behavior Questionnaire (DEBQ) and metabolic equivalent test (MET) were also conducted. The intervention group showed more promising results in weight loss, waist circumference (WC), hip circumference (HC), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and FBS compared to the control group (P < 0.05). In addition, MET and DEBQ scores in all three sections of emotions, stimuli, and restriction were better in the intervention group than in the control group (P < 0.05). However, there was no significant difference between groups regarding the results of serum leptin and waist-to-hip ratio (WHR; p > 0.05).ConclusionsThe results indicated that education through smartphone games could possibly affect performance in real life. In addition, the multi-disciplinary approach to childhood obesity might have better performance in most areas than the single-intervention approach in obesity management.  相似文献   
99.
AimsTreatment decisions for older patients with breast cancer are complex and evidence is largely extrapolated from younger populations. Frailty and comorbidity need to be considered. We studied the baseline characteristics and treatment decisions in older patients in Christchurch with breast cancer and assessed survival outcomes and prognostic/discriminatory performance of several tools.Materials and methodsWe searched the Canterbury Breast Cancer Registry and identified patients aged 70 years or older at diagnosis with invasive, non-metastatic breast cancer between 1 June 2009 and 30 June 2015. We retrieved demographics, treatment and outcome information. Overall survival and breast cancer-specific survival were estimated. Tools analysing performance status and comorbidity were assessed for their prognostic and discriminatory power.ResultsIn total, 440 patients were identified. Primary surgery was carried out for 362 patients (82.3%): breast-conserving surgery in 114 (of whom 88.6% received radiation therapy); mastectomy in 248 (of whom 24.6% received radiation). Hormone therapy was given for 265 (71.1%) patients with oestrogen receptor-positive cancers. Two hundred and seventy-four (62.3%) patients received full standard treatment, which was associated with significantly improved 5-year survival and 5-year breast cancer-specific survival. The median estimated overall survival was 8.2 years (95% confidence interval 7.3–9.1 years). Of those who died, 71.3% of deaths were due to causes other than breast cancer or unknown causes. The comorbidity-adjusted life expectancy (CALE) showed partial prognostic accuracy. CALE, Charlson and Eastern Cooperative Oncology Group tools all showed discriminatory value.ConclusionIn this population-based series of older patients with breast cancer, showing high levels of primary and adjuvant treatment, patients were more likely to die of causes other than breast cancer. Performance status and comorbidity tools showed prognostic and discriminatory potential in this population supporting their use in treatment decision making. CALE showed the most potential to improve treatment decisions but requires validation in this population to improve prognostic accuracy.  相似文献   
100.
《Molecular therapy》2022,30(6):2186-2198
  1. Download : Download high-res image (179KB)
  2. Download : Download full-size image
  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