全文获取类型
收费全文 | 9628篇 |
免费 | 1022篇 |
国内免费 | 14篇 |
专业分类
耳鼻咽喉 | 103篇 |
儿科学 | 255篇 |
妇产科学 | 249篇 |
基础医学 | 1370篇 |
口腔科学 | 290篇 |
临床医学 | 1220篇 |
内科学 | 1888篇 |
皮肤病学 | 96篇 |
神经病学 | 905篇 |
特种医学 | 271篇 |
外国民族医学 | 3篇 |
外科学 | 1241篇 |
综合类 | 183篇 |
一般理论 | 10篇 |
预防医学 | 1145篇 |
眼科学 | 106篇 |
药学 | 696篇 |
中国医学 | 3篇 |
肿瘤学 | 630篇 |
出版年
2022年 | 67篇 |
2021年 | 118篇 |
2020年 | 93篇 |
2019年 | 139篇 |
2018年 | 150篇 |
2017年 | 112篇 |
2016年 | 112篇 |
2015年 | 159篇 |
2014年 | 231篇 |
2013年 | 284篇 |
2012年 | 465篇 |
2011年 | 524篇 |
2010年 | 247篇 |
2009年 | 276篇 |
2008年 | 423篇 |
2007年 | 438篇 |
2006年 | 442篇 |
2005年 | 436篇 |
2004年 | 393篇 |
2003年 | 370篇 |
2002年 | 360篇 |
2001年 | 352篇 |
2000年 | 326篇 |
1999年 | 258篇 |
1998年 | 95篇 |
1997年 | 100篇 |
1996年 | 84篇 |
1995年 | 105篇 |
1994年 | 88篇 |
1993年 | 82篇 |
1992年 | 209篇 |
1991年 | 217篇 |
1990年 | 213篇 |
1989年 | 186篇 |
1988年 | 176篇 |
1987年 | 173篇 |
1986年 | 194篇 |
1985年 | 186篇 |
1984年 | 134篇 |
1983年 | 123篇 |
1982年 | 78篇 |
1981年 | 79篇 |
1979年 | 135篇 |
1978年 | 117篇 |
1977年 | 92篇 |
1976年 | 85篇 |
1975年 | 70篇 |
1974年 | 87篇 |
1973年 | 93篇 |
1972年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Michael B. Batz LaTonia C. Richardson Michael C. Bazaco Cary Chen Parker Stuart J. Chirtel Dana Cole Neal J. Golden Patricia M. Griffin Weidong Gu Susan K. Schmitt Beverly J. Wolpert Joanna S. Zablotsky Kufel R. Michael Hoekstra 《Emerging infectious diseases》2021,27(1):214
Foodborne illness source attribution is foundational to a risk-based food safety system. We describe a method for attributing US foodborne illnesses caused by nontyphoidal Salmonella enterica, Escherichia coli O157, Listeria monocytogenes, and Campylobacter to 17 food categories using statistical modeling of outbreak data. This method adjusts for epidemiologic factors associated with outbreak size, down-weights older outbreaks, and estimates credibility intervals. On the basis of 952 reported outbreaks and 32,802 illnesses during 1998–2012, we attribute 77% of foodborne Salmonella illnesses to 7 food categories (seeded vegetables, eggs, chicken, other produce, pork, beef, and fruits), 82% of E. coli O157 illnesses to beef and vegetable row crops, 81% of L. monocytogenes illnesses to fruits and dairy, and 74% of Campylobacter illnesses to dairy and chicken. However, because Campylobacter outbreaks probably overrepresent dairy as a source of nonoutbreak campylobacteriosis, we caution against using these Campylobacter attribution estimates without further adjustment. 相似文献
102.
Glen Richardson Chris Dusik Lynn Lethbridge Michael Dunbar 《Canadian journal of surgery》2021,64(1):E84
BackgroundObesity is an important comorbidity affecting outcomes after total joint arthroplasty. Consequently, surgeons may delay care of obese patients to first address obesity through different care pathways. The effect of obesity on patient wait times for total joint arthroplasty has not been explored. The purpose of this study was to evaluate the effect of obesity on access to total hip (THA) and knee (TKA) arthroplasty.MethodsThe study data set was constructed from the Nova Scotia Health Authority’s Horizon Patient Folder system and the Patient Access Registry Nova Scotia. Wait time was measured as days between the decision to treat and date of surgery. Body mass index (BMI) was calculated from a preoperative assessment, and patients were grouped into BMI categories. Multivariate log-linear regression was used to test for statistical differences, controlling for confounding factors.ResultsWe observed longer wait times for TKA with increasing BMI weight class. Patients with BMIs greater than 50 had 34% longer waits than reference weight patients. However, THA recipients showed no statistical difference in wait times across weight categories. Furthermore, there was variability among surgeons in the wait times experienced by patients.ConclusionThe finding of longer wait times for TKAs, but not THAs, among patients who were obese was unexpected. This shows the variable wait times for THA and TKA that patients who are obese can experience with different surgeons. It is important to understand the variability in wait times so that efforts to standardize the patient experience can be accomplished. 相似文献
103.
104.
To understand the mechanisms of glaucoma in retinopathy of prematurity (ROP), anterior segment evaluation is essential. The authors prospectively examined the anterior segment of 27 eyes of 17 premature infants with stages IV and V ROP. Twenty-six eyes received no previous surgery or treatment. Schi?tz and applanation tonometry were performed. Structural evaluation of each anterior segment was conducted by biomicroscopy and Koeppe gonioscopy. In the 26 eyes, angle closure of greater than 180 degrees was noted in 3 (12%). The authors noted prominent Schwalbe's line in 4 eyes (15%), high iris convexity in 15 (58%), hypopigmentation of the iris root in 19 (73%), translucent matrix in the angles ("Barkan's-type" membrane) in 18 (69%), posterior synechiae in 16 (62%), visible iris or angle vessels in 12 (46%), and pigment clumping in the angle recess in 12 (46%). This study identified structural abnormalities in the anterior segment of ROP infants, including pathologic changes and anatomic features that could have a developmental origin. 相似文献
105.
Mullen PD Richardson MA Quinn VP Ershoff DH 《American journal of health promotion : AJHP》1997,11(5):323-330
PURPOSE: Despite high rates of spontaneous and assisted smoking cessation during pregnancy, postpartum maintenance is disappointingly low. Predictors of return to smoking remain unclear, thus limiting the development of interventions that could protect the health of women and their children. This study followed women who had participated in a prenatal smoking cessation intervention trial and successfully stopped smoking to address two aims: (1) describe the probability of relapse in confirmed quitters during the first 6 months after the birth, and (2) identify factors that increase relapse. DESIGN: Prospective design during pregnancy and retrospective report at 6 months postpartum used survival analysis with return to smoking as the dependent variable and the Cox proportional hazards regression technique. MEASURES: Questionnaires were used at the first prenatal visit and telephone interviews at the 26th week of pregnancy and 6 months postpartum. Nonsmoking after the 20th week was measured by urine cotinine tests (m = 3); nonsmoking postpartum was measured by retrospective self-report. SETTING: The setting was an HMO-based group practice in Los Angeles. SUBJECTS: Subjects were white, black, and Hispanic women (n = 127) available for follow-up. RESULTS: The proportion of the sample classified as relapsers at 6 months postpartum was 62.9%. The final model identified the following risk factors for smoking: taking puffs in late pregnancy and having friends who smoke at the first prenatal visit, less confidence in mid-pregnancy that they could maintain nonsmoking postpartum, and a partner who smokes postpartum. CONCLUSIONS: Intervention should begin in late pregnancy, and smoking networks, including partner smoking, should be addressed. 相似文献
106.
107.
Richardson M 《Health care management (Philadelphia, Pa.)》1994,1(1):145-155
Persons with disabilities are an important and potentially vulnerable subgroup of the American public. This article discusses both the progress and the promise of health care reform in terms of benefits and impact on persons with physical and/or mental impairments. The author investigates the possibilities implied in the Clinton reform proposals for opportunities to include health promotion, prevention, and early intervention strategies, designed specifically for persons with disabilities. The author also examines the extent to which the reform plan may change the traditional, medically oriented approach to disability. 相似文献
108.
Virginia M. MacDonald John Tsiantis Thomas M. Achenbach Frosso Motti-Stefanidi S. Clive Richardson 《European child & adolescent psychiatry》1995,4(1):1-13
This study compared parent-reported competencies and behavioral/emotional problems in demographically-matched samples of Greek and American children, ages 6–11. Parents of 356 children of each nationality completed the Child Behavior Checklist (CBCL). Competence scores were higher for American children, except on Academic Competence, where scores were higher for Greek children. Greek scores were significantly higher than American scores on the Withdrawn, Anxious/Depressed, Attention Problems, Delinquent Behavior, Aggressive Behavior, Internalizing, Externalizing, and Total Problem scales. On the Anxious/Depressed syndrome, nationality accounted for 14% of the variance. There were few main effects for sex and age and fewer interactions. The higher problem scores in the Greek sample were partly due to the tendency of Greek parents to use extreme item scores. When items were scored present v. absent, Greek scores were higher only on Withdrawn, Anxious/Depressed, Internalizing, and Total Problems, while American scores were higher on Somatic Complaints and Thought Problems. Nationality differences in rates of referral for mental health services and sample differences in exclusion criteria for prior mental health services may have contributed to differences in problem scores. Results are compared to findings from other cross-cultural studies.
Zusammenfassung Diese Studie vergleicht die Fähigkeiten und Verhaltens- bzw. emotionalen Auffälligkeiten in demographisch parallelisierten Stichproben von griechischen und amerikanischen Kindern im Alter von 6-11 Jahren. Die Eltern von 356 Kindern der beiden Nationalitäten füllten die Child Behavior Checklist (CBCL) aus. Die Kompetenzwerte waren bei den amerikanischen Kindern mit Ausnahme der akademischen Fähigkeiten höher. Die griechischen Werte waren signifikant höher als die amerikanischen im Hinblick auf die Skalen Zurückhaltung, ängstlich/depressiv, Aufmerksamkeitsstörungen, delinquentes Verhalten, aggressives Verhalten, Internalisation, Externalisation und Gesamtauffälligkeiten. Im Hinblick auf das ängstlich/depressive Syndrom war die Nationalität für 14% der Varianz verantwortlich. Nur vereinzelt wurden Haupteffekte im Hinblick auf Geschlecht und Alter und eine geringere Anzahl Interaktionen festgestellt. Die höheren Problemwerte in der griechischen Stichprobe waren teilweise durch die Tendenz der griechischen Eltern bedingt, extreme Werte anzukreuzen. Bei den Items, die als vorhanden bzw. nicht vorhanden gewertet werden mußten, waren die griechischen Werte nur bei den Skalen Zurückhaltung, ängstlich/depressiv, Internalisation und Gesamtprobleme höher, während amerikanische Werte für die Skalen körperliche Beschwerden und Denkstörungen höher lagen. Nationalitätsunterschiede der Zuweisungsraten zu psychosozialen Diensten und Stichprobenunterschieden im Hinblick auf die Ausschlußkriterien für vorangegangene Inanspruchnahme psychosozialer Dienste könnten zu den unterschiedlichen Problemwerten beigetragen haben. Die Ergebnisse werden verglichen mit anderen transkulturellen Studien.
Résumé Cette étude a comparé les compétences et les problèmes de comportement et affectifs rapportés par les parents d'un échantillon d'enfants grecs et américains âgés de 6 à 11 ans appariés démographiquement. Les parents de 356 enfants de chaque nationalité ont rempli la Child Behavior Checklist (CBCL). Les scores de compétence étaient plus élevés pour les enfants américains excepté pour la compétence scolaire pour laquelle les scores étaient plus élevés chez les enfants grecs. Les scores grecs étaient significativement plus hauts que les scores américains quant au retrait, l'anxiété-dépression, les problèmes d'attention, le comportement délinquant, le comportement agressif, les échelles d'internalisation, d'externalisation et de problèmes totaux. Pour le syndrome anxiodépressif, la nationalité intervenait pour une variance de 14%. Il y avait peu d'effets principaux en ce qui concerne le sexe et l'âge. Les scores de problèmes les plus élevés dans les échantillons grecs étaient en partie dûs à la tendance des parents grecs à utiliser des items extrêmes. Quand les items étaient cotés présents versus absents, les scores grecs étaient plus élevés seulement en ce qui concerne le retrait, l'anxiété-dépression, l'internalisation et les problèmes totaux tandis que les scores américains étaient plus hauts en ce qui concerne les plaintes somatiques et les problèmes de pensée. Les différences de nationalité en ce qui concerne les taux de référence à des services de santé mentale et les différences des échantillons dans les critères d'exclusion pour l'utilisation antérieure de services de santé mentale, peuvent avoir contribué aux différences dans les scores de problèmes. Les résultats sont comparés aux autres études transculturelles.相似文献
109.
110.
Richardson D Wing S Watson J Wolf S 《Journal of exposure analysis and environmental epidemiology》1999,9(6):575-585
Epidemiological studies of workers employed at the Hanford Site have been underway for nearly 30 years. Although the external radiation dosimetry program at Hanford has been fairly comprehensive, some workers included in previous epidemiological analyses have periods of employment during which there are missing annual external radiation dosimetry records. In this report, employment history records and annual external dosimetry records have been used to investigate the extent of missing annual external dosimetry records for workers at the Hanford facility. A "nearby" procedure for estimating values for missing annual external dosimetry records was evaluated. Among the 33,459 workers who were employed at least 180 days and had at least one annual external dosimetry record, annual external dosimetry records were missing for 8% of the years of employment (32,323 missing annual external dosimetry records). Missing annual external dosimetry records were more common for female Hanford workers than for male workers, and for workers employed in the early years of Hanford's operation than for workers employed in later years of operation. The nearby procedure provided reliable estimates of values for missing annual external dosimetry records. Using this procedure, 18,937.5 mSv were estimated for missing annual external dosimetry records; this was 2% of the total recorded cumulative external radiation dose for these workers. Missing annual external dosimetry records should be considered as a potential source of bias and uncertainty in investigations of radiation-cancer associations among Hanford workers. 相似文献