全文获取类型
收费全文 | 1765篇 |
免费 | 115篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 53篇 |
妇产科学 | 23篇 |
基础医学 | 136篇 |
口腔科学 | 71篇 |
临床医学 | 131篇 |
内科学 | 238篇 |
皮肤病学 | 12篇 |
神经病学 | 55篇 |
特种医学 | 199篇 |
外科学 | 232篇 |
综合类 | 79篇 |
预防医学 | 83篇 |
眼科学 | 399篇 |
药学 | 72篇 |
中国医学 | 26篇 |
肿瘤学 | 63篇 |
出版年
2022年 | 15篇 |
2021年 | 25篇 |
2020年 | 26篇 |
2019年 | 37篇 |
2018年 | 38篇 |
2017年 | 34篇 |
2016年 | 37篇 |
2015年 | 38篇 |
2014年 | 58篇 |
2013年 | 84篇 |
2012年 | 107篇 |
2011年 | 98篇 |
2010年 | 73篇 |
2009年 | 59篇 |
2008年 | 78篇 |
2007年 | 104篇 |
2006年 | 43篇 |
2005年 | 43篇 |
2004年 | 30篇 |
2003年 | 19篇 |
2002年 | 18篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 25篇 |
1998年 | 64篇 |
1997年 | 55篇 |
1996年 | 38篇 |
1995年 | 29篇 |
1994年 | 33篇 |
1993年 | 34篇 |
1992年 | 29篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 45篇 |
1988年 | 48篇 |
1987年 | 55篇 |
1986年 | 41篇 |
1985年 | 35篇 |
1984年 | 17篇 |
1983年 | 20篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 21篇 |
1975年 | 22篇 |
1974年 | 15篇 |
1972年 | 5篇 |
排序方式: 共有1887条查询结果,搜索用时 31 毫秒
41.
S McKenna GA Evans Canadian Infectious Disease Society Antimicrobial Agents Committee 《The Canadian Journal of Infectious Diseases & Medical Microbiology》2001,12(4):218-231
Since the introduction of erythromycin in 1965, no new compounds from the macrolide antimicrobial class were licensed in Canada until the 1990s. Clarithromycin and azithromycin, since their introduction, have become important agents for treating a number of common and uncommon infectious diseases. They have become prime agents in the treatment of respiratory tract infections, and have revolutionized the management of both genital chlamydial infections, by the use of single-dose therapy with azithromycin, and nontuberculous mycobacterial infections, by the use of clarithromycin. The improvement of clarithromycin and azithromycin over the gastrointestinal intolerability of erythromycin has led to supplanting the use of the latter for many primary care physicians. Unfortunately, the use of these agents has also increased the likelihood for misuse and has raised concerns about a resultant increase in the rates of macrolide resistance in many important pathogens, such as Streptococcus pneumoniae. This paper reviews the pharmacology and evidence for the current indications for use of these newer agents, and provides recommendations for appropriate use.Key Words: Azithromycin, Clarithromycin, Erythromycin, Macrolides, Review, Therapeutic useErythromycin A is a naturally occurring, microbiologically active compound of the macrolide class of antibiotics. Chemical modification of erythromycin A''s 14-membered lactone ring has led to the formation of semisynthetic derivatives with not only improved bioavailability and tolerability, but also expanded spectrums of microbiological activity and improved pharmacokinetic profiles. Such modifications produced clarithromycin, classified as a macrolide because it retains the central 14-membered lactone ring (1,2), and azithromycin, classified as an azalide due to its 15-membered aglycone ring (1). The latter two compounds are the newest agents in the macrolide class licensed for use in Canada. Roxithromycin and dirithromycin are available in other countries.These compounds are clinically active against Gram-positive and Gram-negative cocci, and Gram-negative bacilli (primarily Haemophilus influenzae, Legionella species, Moraxella catarrhalis, Campylobacter jejuni, Bordatella pertussis and Helicobacter pylori). Azalides such as azithromycin have exhibited superior activity against Gram-negative pathogens and are generally less active against Gram-positive pathogens. Intracellular pathogens such as Chlamydia species, Mycoplasma species, Ureaplasma species, Borrelia species and nontuberculous mycobacteria species show varying susceptibilities. On the basis of their microbial activity, both the macrolides and azalides have been shown to be clinically useful in the treatment of uncomplicated skin and soft tissue infections, upper and lower respiratory tract infections, sexually transmitted Chlamydia trachomatis infection and peptic ulcer disease. Additionally, the improved pharmacokinetic profiles and acid stability exhibited by the newer agents may lead to enhanced patient adherence through less frequent dosing and improved bioavailability in the presence of food. 相似文献
42.
Arash Babaei-Ghazani Peyman Roomizadeh Bijan Forogh Seyed-Mohammad Moeini-Taba Amin Abedini Mona Kadkhodaie Fateme Jahanjoo Bina Eftekharsadat 《Archives of physical medicine and rehabilitation》2018,99(4):766-775
Objective
To review the literature and assess the comparative effectiveness of ultrasound-guided versus landmark-guided local corticosteroid injections in patients with carpal tunnel syndrome (CTS).Data Sources
Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), Embase (Ovid), and Web of Science (from inception to February 1, 2017).Study Selection
Randomized controlled trials (RCTs) comparing ultrasound-guided injection with landmark-guided injection in patients with CTS were included.Data Extraction
Two authors independently screened abstracts and full texts. The outcomes of interest were Symptom Severity Scale (SSS) and Functional Status Scale (FSS) scores of the Boston Carpal Tunnel Questionnaire and 4 electrodiagnostic parameters, including compound muscle action potential (CMAP), sensory nerve action potential (SNAP), distal motor latency (DML), and distal sensory latency (DSL).Data Synthesis
Overall, 569 abstracts were retrieved and checked for eligibility; finally, 3 RCTs were included (181 injected hands). Pooled analysis showed that ultrasound-guided injection was more effective in SSS improvement (mean difference [MD], ?.46; 95% confidence interval [CI], ?.59 to ?.32; P<.00001), whereas no significant difference was observed between the 2 methods in terms of the FSS (MD, ?.25; 95% CI, ?.56 to .05; P=.10). There were also no statistically significant differences in improvements of CMAP (MD, 1.54; 95% CI, 0.01 to 3.07; P=.05), SNAP (MD, ?0.02; 95% CI, ?6.27 to 6.23; P>.99), DML (MD, .05; 95% CI, ?.30 to .39; P=.80), or DSL (MD, .00; 95% CI, ?.65 to .65; P>.99).Conclusions
This review suggested that ultrasound-guided injection was more effective than landmark-guided injection in symptom severity improvement in patients with CTS; however, no significant differences were observed in functional status or electrodiagnostic improvements between the 2 methods. 相似文献43.
Ying Hao Sumita Sood George Triadafilopoulos Jong Hyeok Kim Zheng Wang Peyman Sahbaie M Bishr Omary Anson W Lowe 《BMC gastroenterology》2007,7(1):24
Background
Esophageal reflux and Barrett's esophagus represent two major risk factors for the development of esophageal adenocarcinoma. Previous studies have shown that brief exposure of the Barrett's-associated adenocarcinoma cell line, SEG-1, or primary cultures of Barrett's esophageal tissues to acid or bile results in changes consistent with cell proliferation. In this study, we determined whether similar exposure to acid or bile salts results in gene expression changes that provide insights into malignant transformation. 相似文献44.
Hourvash Haghighinejad Minoo Tarakemehzadeh Peyman Jafari Mahtab Jafari Mani Ramzi Arvin Hedayati 《Psychiatry investigation》2021,18(3):179
ObjectiveThe aims of this study were to evaluate the psychometric properties of Persian translation of the Yale Food Addiction Scale 2.0 (YFAS 2.0) as a widely accepted questionnaire for the first time and to establish a cut off score for Food Craving Questionnaire-Trait-reduced (FCQ-T-r). MethodsIn this cross-sectional study, 330 visitors of family physician clinics in Shiraz, a city located in south of Iran, were selected. The English version of YFAS 2.0 was translated into Persian and used in this study as well as the Persian version of FCQ-T-r. ResultsConfirmatory factor analysis of YFAS-2 confirmed one dimensional structure and factor loading in all eleven symptoms was above 0.4. Internal consistency for eleven symptoms was 0.813. Prevalence of food addiction in participants was 6.7% (22 participants). BMI and FCQ-T-r questionnaire score both were positively correlated with the number of food addiction symptoms but age was negatively correlated with the number of the symptoms. The ROC curve analysis showed the best suggested cut-off point for FCQ-T-r questionnaire to detect food addiction was 32.5. ConclusionThe present study confirmed validity and reliability of Persian version of YFAS-2. It is suggested that food addiction occurs in different level of food craving behavior in different food cultures or genetics. 相似文献
45.
46.
47.
48.
Molecular heterogeneity in acute leukemia lineage switch 总被引:1,自引:0,他引:1
Gagnon GA; Childs CC; LeMaistre A; Keating M; Cork A; Trujillo JM; Nellis K; Freireich E; Stass SA 《Blood》1989,74(6):2088-2095
Six cases of acute leukemia that underwent lineage switch from acute lymphocytic leukemia to acute myelogenous leukemia are reported. The mean age of the patients was 24 years, time to conversion was 36 months, and survival after conversion was only 3 months. Of the three cases which showed abnormal metaphases at both diagnosis and conversion, two (cases 2, 5) showed related cytogenetic abnormalities, and the third showed (case 3) independent chromosomal changes. Molecular analysis for immunoglobulin heavy chain and T-cell receptor beta chain genes showed that five of the six cases had rearrangement of at least one of these lymphoid associated genes at conversion to acute myelogenous leukemia. The single case (case 3) in which there were no lymphoid gene rearrangements at conversion was also the only case in which independent karyotypic abnormalities at diagnosis and conversion were demonstrated. Our findings suggest that lineage switch can represent either relapse of the original clone with heterogeneity at the molecular level or the emergence of a second new leukemic clone without molecular heterogeneity. 相似文献
49.
Immunoglobulin G from patients with heparin-induced thrombocytopenia binds to a complex of heparin and platelet factor 4 总被引:6,自引:3,他引:6
Heparin-induced thrombocytopenia (HIT) is an important complication of heparin therapy. Although there is general agreement that platelet activation in vitro by the HIT IgG is mediated by the platelet Fc receptor, the interaction among the antibody, heparin, and platelet membrane components is uncertain and debated. In this report, we describe studies designed to address these interactions. We found, as others have noted, that a variety of other sulfated polysaccharides could substitute for heparin in the reaction. Using polysaccharides selected for both size and charge, we found that reactivity depended on two independent factors: a certain minimum degree of sulfation per saccharide unit and a certain minimum size. Hence, highly sulfated but small (< 1,000 daltons) polysaccharides were not reactive nor were large but poorly sulfated polysaccharides. The ability of HIT IgG to recognize heparin by itself was tested by Ouchterlony gel diffusion, ammonium sulfate and polyethylene glycol precipitation, and equilibrium dialysis. No technique demonstrated reactivity. However, when platelet releasate was added to heparin and HIT IgG, a 50-fold increase in binding of radio-labeled heparin to HIT IgG was observed. The releasate was then depleted of proteins capable of binding to heparin by immunoaffinity chromatography. Only platelet factor 4-immunodepleted releasate lost its reactivity with HIT IgG and heparin. Finally, to determine whether the reaction occurred on the surface of platelets or in the fluid phase, washed platelets were incubated with HIT IgG or heparin and after a wash step, heparin or HIT IgG was added, respectively. Reactivity was only noted when platelets were preincubated with heparin. Consistent with these observations was the demonstration of the presence of PF4 on platelets using flow cytometry. These studies indicate that heparin and other large, highly sulfated polysaccharides bind to PF4 to form a reactive antigen on the platelet surface. HIT IgG then binds to this complex with activation of platelets through the platelet Fc receptors. 相似文献
50.
Long‐term efficacy of a 0.07% cetylpyridinium chloride mouth rinse in relation to plaque and gingivitis: a 6‐month randomized,vehicle‐controlled clinical trial
下载免费PDF全文
![点击此处可从《International journal of dental hygiene》网站下载免费的PDF全文](/ch/ext_images/free.gif)