全文获取类型
收费全文 | 6078篇 |
免费 | 398篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 326篇 |
妇产科学 | 165篇 |
基础医学 | 760篇 |
口腔科学 | 51篇 |
临床医学 | 1298篇 |
内科学 | 801篇 |
皮肤病学 | 68篇 |
神经病学 | 475篇 |
特种医学 | 152篇 |
外科学 | 374篇 |
综合类 | 91篇 |
一般理论 | 14篇 |
预防医学 | 875篇 |
眼科学 | 95篇 |
药学 | 508篇 |
1篇 | |
中国医学 | 10篇 |
肿瘤学 | 379篇 |
出版年
2023年 | 24篇 |
2022年 | 37篇 |
2021年 | 59篇 |
2020年 | 41篇 |
2019年 | 111篇 |
2018年 | 123篇 |
2017年 | 85篇 |
2016年 | 103篇 |
2015年 | 99篇 |
2014年 | 132篇 |
2013年 | 285篇 |
2012年 | 425篇 |
2011年 | 446篇 |
2010年 | 253篇 |
2009年 | 162篇 |
2008年 | 417篇 |
2007年 | 427篇 |
2006年 | 401篇 |
2005年 | 443篇 |
2004年 | 408篇 |
2003年 | 365篇 |
2002年 | 415篇 |
2001年 | 32篇 |
2000年 | 42篇 |
1999年 | 33篇 |
1998年 | 87篇 |
1997年 | 82篇 |
1996年 | 61篇 |
1995年 | 69篇 |
1994年 | 64篇 |
1993年 | 56篇 |
1992年 | 36篇 |
1991年 | 32篇 |
1990年 | 37篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 28篇 |
1985年 | 37篇 |
1984年 | 51篇 |
1983年 | 39篇 |
1982年 | 72篇 |
1981年 | 42篇 |
1980年 | 39篇 |
1979年 | 30篇 |
1978年 | 34篇 |
1977年 | 25篇 |
1976年 | 24篇 |
1974年 | 20篇 |
1972年 | 15篇 |
排序方式: 共有6484条查询结果,搜索用时 15 毫秒
1.
2.
Marilyn Sawyer Sommers 《Journal of nursing scholarship》2006,38(4):314-320
PURPOSE: To discuss injury research as a phenomenon of concern in nursing science. ORGANIZING CONSTRUCT: Injury is defined as the physical damage that results when the human body is briefly subjected to intolerable levels of energy. It is the leading cause of death in the first 4 decades of life in high-income nations and is second only to infectious diseases as a leading cause of death in low- and middle-income nations. METHODS: Review and discussion of relevant scientific and theoretical literature in both injury and nursing science. FINDINGS: Nurse scientists can apply unique perspectives to increase understanding of injury and its consequences. Fertile areas for nursing inquiry include identifying people at risk, developing models to explain the association between risk-taking and injury, testing interventions to prevent and limit injury, and creating and refining interventions that are culturally relevant to subpopulations most at risk for injury. CONCLUSIONS: The mandate to improve global heath should lead to nursing inquiry about this phenomenon, including developing and testing interventions to prevent and reduce injury. 相似文献
3.
4.
5.
Marilyn Hravnak Leslie A Hoffman Melissa I Saul Thomas G Zullo Julie F Cuneo Ronald V Pellegrini 《American journal of critical care》2004,13(6):499-507; discussion 508
BACKGROUND: Studies suggest that patients who undergo off-pump coronary artery bypass grafting (OPCABG) have fewer short-term complications and use fewer inpatient resources than do patients who undergo standard coronary artery bypass grafting (CABG) with extracorporeal circulation. However, dissimilarity between groups in risk factors for complications has hindered interpretation of results. OBJECTIVES: To compare the prevalence of selected complications (atrial fibrillation, stroke, reoperation, and bleeding) and inpatient resource utilization (length of stay, discharge disposition, total charges) between subjects undergoing primary isolated CABG or OPCABG who were matched with respect to key risk factors. METHODS: Retrospective, causal-comparative survey conducted in 1 center for 18 months. Patients who underwent primary isolated CABG or OPCABG were matched for sex, age (within 2 years), left ventricular ejection fraction (within 0.05), and graft-patient ratio (exact match) and compared for prevalence of new-onset atrial fibrillation, stroke, reoperation within 24 hours, and bleeding. Statistical analysis included Wilcoxon and t tests for paired comparisons. RESULTS: The sample (107 matched pairs) was 63% male, with a mean age of 66 (SD 9.5) years, a mean left ventricular ejection fraction of 0.51 (SD 0.13), and a mean graft-patient ratio of 3.41 (SD 0.74). The 2 groups did not differ significantly in New York Heart Association class (P = .43), Acute Physiology and Chronic Health Evaluation III score (P = .22), postoperative beta-blocker use (P = .73), or comorbid conditions. None of the complications examined differed significantly between pairs. CONCLUSION: Patients with comparable risk profiles have similar prevalences of selected complications after CABG and OPCABG. 相似文献
6.
7.
Amanda Symington RN MHSc Marilyn Ballantyne RN MHSc Janet Pinelli RN MScN Bonnie Stevens RN PhD 《Journal of obstetric, gynecologic, and neonatal nursing : JOGNN / NAACOG》1995,24(4):321-326
Objective: To determine the effect of indwelling versus intermittent feeding tube placement on weight gain, apnea, and bradycardia in premature neonates.
Design: Eligible subjects were assigned randomly to either feeding tube method. Each subject was followed for 6 days.
Setting: The study was conducted in a secondary level neonatal intensive-care unit (NICU), a tertiary level NICU in a perinatal center, and a tertiary level NICU in a referral center.
Patients/Participants: Neonates who were 24–34 weeks gestational age, developmentally appropriate for gestational age, medically stable, on full enteral feedings through an orogastric or a nasogastric tube, and not fluid restricted. Ninety-three neonates were enrolled-49 in the indwelling group and 44 in the intermittent group. Nine neonates did not complete the study.
Interventions: Nasogastric indwelling feeding tubes were placed and left in site for up to 3 days. Orogastric intermittent feeding tubes were placed for each feeding and removed at completion of the feeding.
Main outcome measures: Weight gain, apnea, and bradycardia. Results: Members of both groups had similar demographic characteristics, clinical problems, and nutritional intake. No statistical differences were found between the two groups in weight gain or episodes of apnea and bradycardia.
Conclusions: There were no statistically or clinically significant differences between the two groups. The intermittent method of feeding is more expensive. Because no clinical differences were found, the type of tube placement chosen for feeding the premature infant may be based on economics. 相似文献
Design: Eligible subjects were assigned randomly to either feeding tube method. Each subject was followed for 6 days.
Setting: The study was conducted in a secondary level neonatal intensive-care unit (NICU), a tertiary level NICU in a perinatal center, and a tertiary level NICU in a referral center.
Patients/Participants: Neonates who were 24–34 weeks gestational age, developmentally appropriate for gestational age, medically stable, on full enteral feedings through an orogastric or a nasogastric tube, and not fluid restricted. Ninety-three neonates were enrolled-49 in the indwelling group and 44 in the intermittent group. Nine neonates did not complete the study.
Interventions: Nasogastric indwelling feeding tubes were placed and left in site for up to 3 days. Orogastric intermittent feeding tubes were placed for each feeding and removed at completion of the feeding.
Main outcome measures: Weight gain, apnea, and bradycardia. Results: Members of both groups had similar demographic characteristics, clinical problems, and nutritional intake. No statistical differences were found between the two groups in weight gain or episodes of apnea and bradycardia.
Conclusions: There were no statistically or clinically significant differences between the two groups. The intermittent method of feeding is more expensive. Because no clinical differences were found, the type of tube placement chosen for feeding the premature infant may be based on economics. 相似文献
8.
9.
John B. Mailhes Marilyn J. Aardema Francesco Marchetti 《Environmental and molecular mutagenesis》1993,22(2):107-114
The various causative and mechanistic phenomena associated with aneuploidy induction require considerable investigation to better understand the etiology of chromosome missegregation. We investigated the potential of vinblastine sulfate, pyrimethamine, diethylstilbestrol diphosphate, and chloral hydrate to induce numerical and structural chromosome changes in female mouse germ cells. Superovulated ICR mice were administered the compounds either by intraperitoneal injection or oral gavage, and oocytes were collected and processed for cytogenetic analysis 17 hr later. Vinblastine sulfate, administered i.p., induced a significant increase in the frequency of ovulated Ml oocytes and of hyperploid Mll oocytes compared to controls, but did not increase the frequency of structural aberrations. Pyrimethamine, diethylstilbestrol diphosphate, and chloral hydrate did not increase the frequency of numerical or structural chromosome changes in female mouse germ cells. © 1993 Wiley-Liss, Inc. 相似文献
10.
Paul G. Egland Dale A. Pelletier Marilyn Dispensa Jane Gibson Caroline S. Harwood 《Proceedings of the National Academy of Sciences of the United States of America》1997,94(12):6484-6489
A reductive benzoate pathway is the central conduit for the anaerobic biodegradation of aromatic pollutants and lignin monomers. Benzene ring reduction requires a large input of energy and this metabolic capability has, so far, been reported only in bacteria. To determine the molecular basis for this environmentally important process, we cloned and analyzed genes required for the anaerobic degradation of benzoate and related compounds from the phototrophic bacterium, Rhodopseudomonas palustris. A cluster of 24 genes was identified that includes twelve genes likely to be involved in anaerobic benzoate degradation and additional genes that convert the related compounds 4-hydroxybenzoate and cyclohexanecarboxylate to benzoyl-CoA. Genes encoding benzoyl-CoA reductase, a novel enzyme able to overcome the resonance stability of the aromatic ring, were identified by directed mutagenesis. The gene encoding the ring-cleavage enzyme, 2-ketocyclohexanecarboxyl-CoA hydrolase, was identified by assaying the enzymatic activity of the protein expressed in Escherichia coli. Physiological data and DNA sequence analyses indicate that the benzoate pathway consists of unusual enzymes for ring reduction and cleavage interposed among enzymes homologous to those catalyzing fatty acid degradation. The cloned genes should be useful as probes to identify benzoate degradation genes from other metabolically distinct groups of anaerobic bacteria, such as denitrifying bacteria and sulfate-reducing bacteria. 相似文献