全文获取类型
收费全文 | 10733篇 |
免费 | 610篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 84篇 |
儿科学 | 335篇 |
妇产科学 | 304篇 |
基础医学 | 1855篇 |
口腔科学 | 273篇 |
临床医学 | 1010篇 |
内科学 | 1961篇 |
皮肤病学 | 170篇 |
神经病学 | 1112篇 |
特种医学 | 496篇 |
外科学 | 1265篇 |
综合类 | 90篇 |
一般理论 | 3篇 |
预防医学 | 920篇 |
眼科学 | 133篇 |
药学 | 707篇 |
中国医学 | 29篇 |
肿瘤学 | 620篇 |
出版年
2022年 | 70篇 |
2021年 | 156篇 |
2020年 | 105篇 |
2019年 | 140篇 |
2018年 | 172篇 |
2017年 | 134篇 |
2016年 | 170篇 |
2015年 | 219篇 |
2014年 | 276篇 |
2013年 | 389篇 |
2012年 | 659篇 |
2011年 | 696篇 |
2010年 | 402篇 |
2009年 | 368篇 |
2008年 | 614篇 |
2007年 | 647篇 |
2006年 | 637篇 |
2005年 | 645篇 |
2004年 | 586篇 |
2003年 | 521篇 |
2002年 | 547篇 |
2001年 | 107篇 |
2000年 | 70篇 |
1999年 | 103篇 |
1998年 | 130篇 |
1997年 | 99篇 |
1996年 | 84篇 |
1995年 | 88篇 |
1994年 | 71篇 |
1993年 | 69篇 |
1992年 | 48篇 |
1991年 | 61篇 |
1990年 | 47篇 |
1989年 | 54篇 |
1985年 | 50篇 |
1984年 | 55篇 |
1983年 | 46篇 |
1982年 | 49篇 |
1977年 | 47篇 |
1974年 | 51篇 |
1933年 | 71篇 |
1932年 | 59篇 |
1931年 | 57篇 |
1930年 | 52篇 |
1929年 | 44篇 |
1928年 | 45篇 |
1927年 | 52篇 |
1926年 | 54篇 |
1925年 | 49篇 |
1924年 | 52篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Michael Gottsauner-Wolf Johanna Schedimayer-Duit Gerold Porenta Marianne Gwechenberger Kurt Huber Dietmar Giogar Peter Probst Heinz Sochor 《European journal of nuclear medicine and molecular imaging》1996,23(12):1613-1618
Measurement of global left ventricular function is important in the follow-up of cardiac patients and is a good prognostic indicator in acute cardiac situations. We compared quantitative measurements of global left ventricular function made with radionuclide angiography (RNA) and contrast cardiac ventriculography (CVG) to visual semiquantitative estimates from two-dimensional echocardiographic images (2D-echo). Three hundred and thirty-nine consecutive patients who underwent RNA were assessed with 2D-echo within 3 months. In addition, 92 of these patients also underwent CVG (correlation of ejection fraction between CVG and RNA:r=0.82;P<0.0001). The RNA mean ejection fractions in the four 2D-echo groups (0=normal, 1=slightly, 2=moderate, or 3=severe reduced left ventricular function) differed markedly (P<0.0001); however, there was overlapping among the groups (2D-echo score/RNA ejection fraction: 0=57.3%±12.8%; 1=46.0%±12.9%; 2=29.6%±12.2%; and 3=24.6%±11.5%) and the difference between 2D-echo scores 2 and 3 was not significant. 2D-echo showed a good concordance in RNA classes (0=505; 1=35%–49%; 2=21%–34%; and 3=520% ejection fraction) 0 (133/166; 80%) and 3 (18/30; 60%) but low concordance in classes 1 (27/82; 33%) and 2 (21/61; 34%). For accurate assessment of global left ventricular ejection fraction, visual semiquantitative judgement of a 2D echocardiographic image is limited in comparison to CVG or RNA, especially in patients with a slight or moderate reduction in left ventricular ejection fraction. 相似文献
42.
Kurt Krejcy Gunther Krumpl Hannes Todt Gerhard Raberger 《Naunyn-Schmiedeberg's archives of pharmacology》1992,346(2):213-218
Summary The aim of the present study was to investigate the dose-dependent antiarrhythmic efficacy of lidocaine against electrically induced tachycardias in conscious, chronically instrumented postinfarction dogs. Programmed electrical stimulation (PES) was performed in 16 dogs 8 to 21 days after a 4 h occlusion of the left anterior descending coronary artery (LAD). Infusion of saline in 8 control animals with sustained ventricular tachycardia (SVT) inducible at baseline did not affect subsequent inducibility. In the treatment group 7 of 8 animals responded with SVT and one exhibited ventricular fibrillation at baseline. After an initial bolus of 1 mg/kg lidocaine intravenously (i.v.), the drug was infused at infusion rates of 40, 80 and 120 g/kg/min (i.v.). During 80 g/kg/min lidocaine (mean plasma level 3.5 g/ml) 7 out of 8 animals displayed an antiarrhythmic response; both the lower and the higher infusion rate were associated with a smaller antiarrhythmic efficacy (3 of 8 animals responded to 40 g/kg/min and 4 of 8 to 120 g/kg/min). Licocaine did not affect ventricular refractory periods, but induced an increase in intraventricular conduction time at all infusion rates, from 66.2 ms at baseline to 67.7 ms (p<0.05), 67.7 ms (p<0.05), 70.0 ms (p<0.01) respectively.In conclusion the present study demonstrates that lidocaine is of considerable value in the management of PES-induced ventricular arrhythmias in the postinfarction phase. However there is only a small optimal therapeutic plasma level range, where lidocaine exhibits its antiarrhythmic efficacy against this type of arrhythmia; this makes a carefully titration of the drug necessary both in the experimental and in the clinical setting.
Send offprint requests to K. Krejcy at the above address 相似文献
43.
Kurt Freund MD DSc Robin Watson MEd Robert Dickey MD 《Sexual abuse : a journal of research and treatment》1991,4(1):93-105
The rationale for dividing the clinical spectrum of DSM-III-R male heterosexual gender identity disorder into three types was examined. The DSM-III-R category of fetishism for female attire, was included in the analysis. There were 266 male participants divided into three groups: 172 fetishists for female attire or gender identity patients, 52 androphiles, and 42 gynephiles. A 16 item questionnaire was used to examine the groups. A three factor scale ("Fetishism", "Gender Dysphoria" and "Androphilia") was derived from the questionnaire. Only the Gender Dysphoria Factor Scale successfully differentiated between all four conditions, supporting the notion that the three types of gender identity disorder represent a continuum of degree of severity of gender dysphoria. Defining two of the three types of gender identity disorder in terms of the patients' self-reports on fetishism, as DSM-III-R does, is therefore unnecessary. 相似文献
44.
Steven C. Schimmel James M. Patrick Jr. Jerrold Forester 《Archives of environmental contamination and toxicology》1977,5(1):353-367
The organochlorine insecticide, toxaphene, was tested in flow-through bioassays to evaluate its toxicity to estuarine organisms. The organisms tested and their respective 96-hr LC5Os (based on measured concentrations) are: pink shrimp (Penaeus duorarum), 1.4g/L; grass shrimp (Palaemonetes pugio), 4.4g/L; sheepshead minnow (Cyprinodon variegatus), 1.1g/L; and pinfish (Lagodon rhomboides), 0.5g/L. Toxaphene concentration estimated to reduce shell deposition in American oysters (Crassostrea virginica) by 50% (EC50) was 16g/L. Concentration factors (concentration of toxaphene in tissues divided by concentration measured in water) for fishes and oysters in 96 hr ranged from 3,100 to 20,600 and for shrimp, from 400 to 1,200.Individuals from various ontogenetic stages of longnose killifish (Fundulus similis) were exposed to toxaphene for 28 days in flow-through bioassays. Toxaphene was toxic to embryos, fry, juveniles, and adult fish, but fertilization of ova in static tests was not affected by the concentrations tested (0.32 to 10g/L). The 28-day measured LC50s for all stages ranged from 0.9 to 1.4g/L. Toxaphene was accumulated in ova and other body tissues of the longnose killifish; concentration factors in ova were 1,000 to 5,500, and in whole-body tissues, 4,200 to 60,000.Contribution No. 269, Gulf Breeze Environmental Research Laboratory.Portions relating toFundulus similis based on a thesis submitted by S.C.S. in partial fulfillment of the degree of Master of Science from the University of West Florida, 1975. 相似文献
45.
M Kaplan E Kaplan C Hammerman N Algur R Bromiker M S Schimmel A I Eidelman 《Archives of disease in childhood》2006,91(1):31-34
AIM: To determine the incidence of post-phototherapy neonatal plasma total bilirubin (PTB) rebound. METHODS: A prospective clinical survey was performed on 226 term and near-term neonates treated with phototherapy in the well baby nursery of the Shaare Zedek Medical Center from January 2001 to September 2002. Neonates were tested for PTB 24 hours (between 12 and 36 hours) after discontinuation of phototherapy, with additional testing as clinically indicated. The main outcome measure, significant bilirubin rebound, was defined as a post-phototherapy PTB > or =256 micromol/l. Phototherapy was not reinstituted in all cases of rebound, but rather according to clinical indications. RESULTS: A total of 30 (13.3%) neonates developed significant rebound (mean (SD) PTB 287 (27) micromol/l, upper range 351 micromol/l). Twenty two of these (73%) were retreated with phototherapy at mean PTB 296 (29) micromol/l. Multiple logistic regression analysis showed significant risk for aetiological risk factors including positive direct Coombs test (odds ratio 2.44, 95% CI 1.25 to 4.74) and gestational age <37 weeks (odds ratio 3.21, 95% CI 1.29 to 7.96). A greater number of neonates rebounded among those in whom phototherapy was commenced < or =72 hours (26/152, 17%) compared with >72 hours (4/74, 5.4%) (odds ratio 3.61, 95% CI 1.21 to 10.77). CONCLUSION: Post-phototherapy neonatal bilirubin rebound to clinically significant levels may occur, especially in cases of prematurity, direct Coombs test positivity, and those treated < or =72 hours. These risk factors should be taken into account when planning post-phototherapy follow up. 相似文献
46.
The T393C polymorphism of the G alpha s gene (GNAS1) is a novel prognostic marker in bladder cancer. 总被引:2,自引:0,他引:2
Ulrich H Frey Andreas Eisenhardt Gerd Lümmen Herbert Rübben Karl-Heinz J?ckel Kurt W Schmid Winfried Siffert 《Cancer epidemiology, biomarkers & prevention》2005,14(4):871-877
The G protein G(alpha)s pathway is linked to proapoptotic signaling in cancer cell lines. To assess the role of the GNAS1 locus encoding G(alpha)s as a genetic factor for disease progression of transitional cell carcinoma (TCC) of the bladder, we genotyped the synonymous T393C polymorphism in 254 patients with TCC (minor allele frequency: 0.43) to examine a potential association between genotypes and disease progression. Using Kaplan-Meier estimates to calculate 5-year probabilities of follow-up, we could show that progression-free survival, metastasis-free survival, and cancer-specific survival was significantly increased in TT genotypes (56%, 84%, 82%) compared with CC genotypes (35%, 53%, 58%). In multivariate Cox proportional hazard analysis, the T393C polymorphism was an independent prognostic factor for clinical outcome. Homozygous CC patients were at highest risk for progression [odds ratio (OR), 1.94; P = 0.020], metastasis (OR, 3.49; P = 0.005), and tumor-related death (OR, 2.49; P = 0.031) compared with TT genotypes. Heterozygous patients had an intermediate risk compatible with a gene-dose effect. Real-time PCR analysis of urothelial tumor tissue as well as adipose and heart tissue revealed that G(alpha)s mRNA expression was highest in TT genotypes, indicating a proapoptotic effect in these genotypes. In conclusion, the GNAS1 T393C status associated with differential G(alpha)s mRNA expression is a novel independent prognostic marker for clinical outcome supporting a functional role of G(alpha)s in bladder cancer progression. 相似文献
47.
Kurt B Stevenson Matthew Samore James Barbera Elizabeth Hannah James W Moore Julie L Gerberding Peter Houck 《American journal of health-system pharmacy》2004,61(8):787-792
PURPOSE: Pharmacist involvement in antimicrobial use at small rural hospitals in four Western states was studied. METHODS: Surveys were mailed in July 2000 to hospitals with a daily patient census of <150 in Idaho, Nevada, Utah, and eastern Washington. RESULTS: Seventy-seven (77%) of 100 hospitals returned completed surveys. Only 5% of the hospitals had onsite pharmacists 24 hours per day. An onsite pharmacist was present for a median of 26 hours per week in hospitals without 24-hour pharmacist coverage (range, 0-116 hr/wk). Many hospitals (71%) had policies for monitoring or controlling antimicrobial use, but only 28% had a system capable of monitoring compliance with such policies. Few hospitals had systems for recommending changes in antimicrobial selection on the basis of susceptibility test results (27%) or for monitoring physician compliance with dosage recommendations by pharmacists (21%). Onsite pharmacist hours were significantly associated with pharmacists being involved in the initial ordering of antibiotics and providing active oversight of antimicrobial use. There was a negative correlation between onsite pharmacist hours and use of third-generation cephalosporins and carbapenems. CONCLUSION: A survey showed that rural hospital pharmacists in four Western states spent relatively little time monitoring and influencing antimicrobial prescribing. 相似文献
48.
Queiroz EF Atindehou KK Terreaux C Antus S Hostettmann K 《Journal of natural products》2002,65(3):403-406
Four new prenylated isoflavonoids, vogelins D-G (1-4), were isolated from the CH2Cl2 extract of Erythrina vogelii root bark in addition to the known compounds isolupalbigenin (5), ficuisoflavone (6), ulexone (7), isochandalon (8), and isoderrone (9). The structures 1-4 were elucidated by spectroscopic and chemical methods. The absolute configuration of compound 1 was determined on the basis of its CD spectrum. Possible biogenetic relationships among the E. vogelii isoflavonoids are briefly discussed. 相似文献
49.
Barnhart KT Rinaudo P Hummel A Pena J Sammel MD Chittams J 《Fertility and sterility》2003,80(6):1345-1351
OBJECTIVE: The diagnosis of ectopic pregnancy (EP) is often confirmed at presentation (acute), but often requires serial beta-hCG levels to confirm the diagnosis (chronic). The purpose of this study is to analyze whether these clinical presentations represent a spectrum of disease. DESIGN: The retrospective cohort study of 452 patients diagnosed with EP at the University of Pennsylvania in the years 1990-1999. SETTING: University of Pennsylvania, Philadelphia, Pennsylvania. PATIENT(S): Four hundred fifty-two patients diagnosed with EP. Patients diagnosed with EP were divided into two groups according to the time of diagnosis. MAIN OUTCOME MEASURE(S): A total of 37 parameters were examined including historic and demographic factors, findings at presentation, and treatment and outcome variables. RESULT(S): The two groups were similar in terms of historic EP risk factors. Multivariable analysis demonstrates that women with a chronic presentation were less likely to have received fertility medications (odds ratio [OR] 0.23; 95% confidence interval [CI] 0.06-0.84), less likely to present with pain (OR 0.29; 95% CI 0.12-0.71), have a lower beta-hCG level at presentation (9,849 mIU/mL +/- 16,726 vs. 1,787 mIU/mL +/- 4,717), lower chance of rupture (OR 0.19; 95% CI 0.05-0.73), and less frequently have blood type 0. CONCLUSION(S): Women diagnosed with ectopic pregnancy can be categorized into two groups, those with an acute presentation and those with a chronic presentation. Differences in risk factors, presentation, and outcome may reflect differences in trophoblast viability or invasive potential. 相似文献
50.