全文获取类型
收费全文 | 22084篇 |
免费 | 1408篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 146篇 |
儿科学 | 718篇 |
妇产科学 | 780篇 |
基础医学 | 2897篇 |
口腔科学 | 313篇 |
临床医学 | 3608篇 |
内科学 | 4054篇 |
皮肤病学 | 220篇 |
神经病学 | 2129篇 |
特种医学 | 360篇 |
外科学 | 1748篇 |
综合类 | 305篇 |
一般理论 | 35篇 |
预防医学 | 3146篇 |
眼科学 | 274篇 |
药学 | 1292篇 |
中国医学 | 13篇 |
肿瘤学 | 1493篇 |
出版年
2023年 | 98篇 |
2022年 | 183篇 |
2021年 | 382篇 |
2020年 | 229篇 |
2019年 | 418篇 |
2018年 | 432篇 |
2017年 | 306篇 |
2016年 | 384篇 |
2015年 | 443篇 |
2014年 | 658篇 |
2013年 | 1038篇 |
2012年 | 1468篇 |
2011年 | 1487篇 |
2010年 | 844篇 |
2009年 | 817篇 |
2008年 | 1448篇 |
2007年 | 1421篇 |
2006年 | 1432篇 |
2005年 | 1448篇 |
2004年 | 1376篇 |
2003年 | 1354篇 |
2002年 | 1326篇 |
2001年 | 203篇 |
2000年 | 206篇 |
1999年 | 235篇 |
1998年 | 270篇 |
1997年 | 235篇 |
1996年 | 198篇 |
1995年 | 212篇 |
1994年 | 178篇 |
1993年 | 180篇 |
1992年 | 175篇 |
1991年 | 162篇 |
1990年 | 148篇 |
1989年 | 143篇 |
1988年 | 132篇 |
1987年 | 134篇 |
1986年 | 103篇 |
1985年 | 105篇 |
1984年 | 152篇 |
1983年 | 143篇 |
1982年 | 173篇 |
1981年 | 145篇 |
1980年 | 160篇 |
1979年 | 91篇 |
1978年 | 95篇 |
1977年 | 70篇 |
1976年 | 68篇 |
1974年 | 60篇 |
1973年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Judith D. DePue Elizabeth L. McQuaid Daphne Koinis-Mitchell Christopher Camillo Anthony Alario Robert B. Klein 《The Journal of asthma》2007,44(6):449-453
Over 3 years, 972 families participated in an after-school asthma program at their child's school. Parents and children attended concurrent 21/2 -hour workshops. Parents were 74% Latino; 45% non-English speaking, with 77% of children on Medicaid. Asthma symptoms were significantly reduced, from multiple times per week to less than once per week on average. Oral steroid use decreased to one third of baseline use. Hospital days decreased from 11% to 2%; emergency visits decreased 35% to 4%; and school days missed decreased 48% to 20%. This program has now become sustainable with both private and Medicaid insurance coverage. 相似文献
52.
53.
54.
55.
Celeste A. Lemay Suzanne B. Cashman Judith A. Savageau Patricia A. Reidy 《Journal of nursing scholarship》2004,36(4):312-315
PURPOSE: Evaluate the effectiveness of body mass index (BMI) tables placed in exam rooms as an intervention to encourage providers to calculate and record BMI scores in patients' medical records. DESIGN: In a prospective cohort design, medical record data for 276 adult patients at a federally funded community health center in New England were examined from August 2000 to August 2002 following the intervention. METHODS: Prominent, multicolored, laminated BMI tables were posted in the exam rooms of one of the study site's three primary health care teams. Medical record data collected included documentation of BMI calculation in medical records, documentation of an obesity diagnosis, and inclusion of heights and current weights. Frequency distributions were calculated; chi-square tests were used to identify associations. FINDINGS: In contrast to the comparison teams, patients on the intervention team were more likely to have BMI recorded in the medical record. A statistically significant increase in the diagnosis of obesity was observed throughout the health center after the intervention. CONCLUSIONS: Posting BMI tables in exam rooms contributed to increased BMI documentation in patients' medical records. 相似文献
56.
Ravindra Patel Joseph J. McArdle Timothy J. Regan 《Alcoholism, clinical and experimental research》1991,15(5):785-789
An increased incidence of sudden death has been reported in chronic alcoholism. To assess electrical vulnerability of the heart, action potential responses, and the role of the sympathetic system, a well-nourished canine model has been studied intact under chloralose anesthesia after 1 year of ethanol consumption at 36% of caloric intake. Two alcoholic groups were compared with controls (Group 1). In Group 2 myocardial vulnerability was assessed after chronic EtOH and superimposed acute administration. In Group 3 basal vulnerability was related to circulating norepinephrine and release of neurohormone from the myocardium. Subsequently the responsiveness to catecholamine infusion was determined. To assess vulnerability an electrode catheter was placed in the right ventricular apex. The basal ventricular fibrillation threshold (VFT) was reduced to 27 +/- 3 ma in Group 2 versus 43 +/- 1.0 in Group 1. Acute infusion of ethanol in Group 2 further reduced the threshold. Group 3 had a reduced basal VFT. Baseline arterial plasma levels of norepinephrine were 8-fold higher and coronary venous levels 13 times higher in the alcoholic group than in Group 1. However, VFT was not responsive to infused epinephrine, compared with Group 1 controls. In vitro study of superfused ventricular tissue from Group 3 revealed that basal action potential amplitude, overshoot, and resting potential were comparable with normals. Basal repolarization time (90%) was 198 +/- 12 msec in Group 3 versus 215 +/- 6 msec in Group 1 (p less than 0.05). After acute EtOH, repolarization time was shortened to 170 +/- 8.6 in Group 1 at 90 mg% ethanol (p less than 0.002), with minimal further change up to 280 mg%.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
57.
Giedd Jay N.; Snell John W.; Lange Nicholas; Rajapakse Jagath C.; Casey B. J.; Kozuch Patricia L.; Vaituzis A. Catherine; Vauss Yolanda C.; Hamburger Susan D.; Kaysen Debra; Rapoport Judith L. 《Cerebral cortex (New York, N.Y. : 1991)》1996,6(4):551-559
Brain magnetic resonance images (MRI) of 104 healthy childrenand adolescents, aged 418, showed significant effectsof age and gender on brain morphometry. Males had larger cerebral(9%) and cerebellar (8%) volumes (P < 0.0001 and P = 0.008.respectively), which remained significant even after correctionfor height and weight After adjusting for cerebral size, theputamen and globus pallidus remained larger in males, whilerelative caudate size was larger in females. Neither cerebralnor cerebellar volume changed significantly across this agerange. Lateral ventricular volume increased significantly inmales (trend for females), with males showing an increase inslope after age 11. In males only, caudate and putamen decreasedwith age (P = 0.007 and 0.05, respectively). The left lateralventricles and putamen were significantly greater than the rightP = 0.01 and 0.0001, respectively). In contrast, the cerebralhemispheres and caudate showed a highly consistent right greater-than-leftasymmetry (P < 0.0001 for both). All volumes demonstrateda high degree of variability. These findings highlight gender-specificmaturational changes of the developing brain and the need forlarge gender-matched samples in pediatric neuropsychiatric studies. 相似文献
58.
Summary The influence of cholinergic and dopaminergic agents on the acquisition of a passive avoidance response in the rat is demonstrated. Trifluoperazine (0.12 mg/kg), a dopamine antagonist, inhibited task acquisition when present during training or later, during consolidation, at the 10–12 h posttraining period and at no other intervening time point. Induction of amnesia was dose-dependent and was not apparent when the dose exceeded 0.12 mg/ kg. This effect appears to be due to an increase in dopamine release through presynaptic receptor antagonism as similar results could be obtained by the administration of apomorphine (0.5 mg/kg), a dopamine agonist, and this effect could be antagonized by the D 1 receptor selective antagonist SCH-23390. Scopolamine (0.15 mg/kg), a muscarinic antagonist, impaired acquisition of the passive avoidance response when administered during training and, separately, at the 6 h post-training period. This could not be attributed to presynaptic antagonism as oxotremorine (0.2 mg/kg), a muscarinic agonist, had no amnesic action. Administration of apomorphine or scopolamine during training and at the appropriate post-training period prevented subsequent paradigm-specific increases of neural cell adhesion molecule sialylation state in hippocampal immunoprecipitates obtained at 24 h after task acquisition and 4 h following intraventricular infusion of the labelled sialic acid precursor — N-acetyl-D-mannosamine. Oxotremorine alone did not influence neural cell adhesion molecule sialylation state. These observations provide further evidence of a regulatory role for neural cell adhesion molecule sialylation state in information storage processes.Abbreviations
NCAM
neural cell adhesion molecule
-
RSA
relative specific activity
-
SDS-PAGE
sodium dodecyl sulphate polyacrylamide gel electrophoresis
-
TCA
trichloroacetic acid
-
TFP
trifluoperazine 相似文献
59.
Critical care nurses, ethical decision-making and stress 总被引:2,自引:0,他引:2
Considerable attention has focused on describing ethical issues that critical care nurses face in their practice; however, less attention has been directed at describing the process of ethical decision-making. Systematic research linking aspects of ethical-decision making and stress is lacking. This cross-sectional study examines the relationship between selected aspects of ethical decision-making, stress and selected nurse characteristics. Sixty-one critical care nurses completed the Nurse's Ethical Decision Making—ICU Questionnaire and the Health Professions Stress Inventory. Findings revealed that nurses who selected the patient advocacy model had significantly higher nurse autonomy scores, that perceived anxiety had a negative association with nurse autonomy, and that workplace restrictions and stress were related. 相似文献
60.
Nonadrenergic [3H]idazoxan binding sites are physically distinct from alpha 2-adrenergic receptors 总被引:4,自引:0,他引:4
M C Michel J W Regan M A Gerhardt R R Neubig P A Insel H J Motulsky 《Molecular pharmacology》1990,37(1):65-68
We have recently demonstrated that the alpha 2-adrenergic radioligand [3H]idazoxan also labels additional sites that do not recognize catecholamines but bind with high affinity several chemically distinct drugs previously assumed to be highly selective for alpha 2-adrenergic receptors [Mol. Pharmacol. 35:324-330 (1989)]. We now have used three approaches to distinguish the nonadrenergic [3H]idazoxan sites from alpha 2-adrenergic receptors. (a) No nonadrenergic [3H]idazoxan binding sites were found in COS-7 cells transfected with the genes for the two known alpha 2-adrenergic receptor subtypes. (b) The ratio of alpha 2-adrenergic and nonadrenergic [3H]idazoxan sites in human platelet membranes varied considerably between various donors. (c) Highly purified platelet plasma membranes were enriched for alpha 2-adrenergic receptors but did not contain any nonadrenergic [3H]idazoxan binding sites. We conclude that the nonadrenergic [3H]idazoxan binding sites are not co-expressed with alpha 2-adrenergic receptors and at least in human platelets may be located in an intracellular compartment. 相似文献