全文获取类型
收费全文 | 180666篇 |
免费 | 13884篇 |
国内免费 | 697篇 |
专业分类
耳鼻咽喉 | 2247篇 |
儿科学 | 4631篇 |
妇产科学 | 3735篇 |
基础医学 | 23917篇 |
口腔科学 | 4083篇 |
临床医学 | 18858篇 |
内科学 | 35775篇 |
皮肤病学 | 2323篇 |
神经病学 | 15569篇 |
特种医学 | 7346篇 |
外国民族医学 | 1篇 |
外科学 | 27628篇 |
综合类 | 2753篇 |
现状与发展 | 1篇 |
一般理论 | 195篇 |
预防医学 | 17467篇 |
眼科学 | 3985篇 |
药学 | 12946篇 |
4篇 | |
中国医学 | 232篇 |
肿瘤学 | 11551篇 |
出版年
2022年 | 1296篇 |
2021年 | 3172篇 |
2020年 | 1799篇 |
2019年 | 2984篇 |
2018年 | 3611篇 |
2017年 | 2702篇 |
2016年 | 2802篇 |
2015年 | 3361篇 |
2014年 | 4877篇 |
2013年 | 7430篇 |
2012年 | 10843篇 |
2011年 | 11507篇 |
2010年 | 6353篇 |
2009年 | 5716篇 |
2008年 | 10115篇 |
2007年 | 10844篇 |
2006年 | 10423篇 |
2005年 | 10559篇 |
2004年 | 10062篇 |
2003年 | 9416篇 |
2002年 | 9254篇 |
2001年 | 2856篇 |
2000年 | 2732篇 |
1999年 | 2812篇 |
1998年 | 2221篇 |
1997年 | 1778篇 |
1996年 | 1733篇 |
1995年 | 1712篇 |
1994年 | 1446篇 |
1993年 | 1431篇 |
1992年 | 2083篇 |
1991年 | 2016篇 |
1990年 | 1885篇 |
1989年 | 1793篇 |
1988年 | 1731篇 |
1987年 | 1722篇 |
1986年 | 1661篇 |
1985年 | 1732篇 |
1984年 | 1604篇 |
1983年 | 1476篇 |
1982年 | 1551篇 |
1981年 | 1528篇 |
1980年 | 1355篇 |
1979年 | 1281篇 |
1978年 | 1176篇 |
1977年 | 999篇 |
1976年 | 910篇 |
1975年 | 836篇 |
1974年 | 915篇 |
1973年 | 871篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
141.
David C. Cone MD Susan M. Nedza MD MBA James J. Augustine MD Steven J. Davidson MD MBA 《Academic emergency medicine》2002,9(11):1085-1090
This paper reports the proceedings of the discussion panel assigned to look at clinical aspects of quality in emergency medicine. One of the seven stated objectives of the Academic Emergency Medicine consensus conference on quality in emergency medicine was to educate emergency physicians regarding quality measures and quality improvement as essential aspects of the practice of emergency medicine. Another topic of interest was a discussion of the value of information technology in facilitating quality care in the clinical practice of emergency medicine. It is important to note that this is not intended to be a comprehensive review of this extensive topic, but instead is designed to report the discussion that occurred at this session of the consensus conference. 相似文献
142.
Modulating effects of posttraining epinephrine on memory: Involvement of the amygdala noradrenergic system 总被引:5,自引:0,他引:5
These experiments examined the effects, on retention, of posttraining intra-amygdala administration of norepinephrine (NE), and propranolol. Rats were trained on a one-trial step-through inhibitory avoidance task and tested for retention 24 h later. Injections were administered bilaterally (1.0 microliter/injection) through chronically-implanted cannulae. Low doses of NE (0.1 or 0.3 microgram) administered shortly after training enhanced retention while higher doses (1.0 or 5.0 micrograms) were ineffective. Retention was not affected by NE administered 3 h after training. The effect of intra-amygdala NE on retention is blocked by simultaneous administration of propranolol (0.2 microgram). This finding suggests that the memory-enhancing effect of NE may be mediated by beta-receptors. Posttraining intra-amygdala NE also attenuated the retention deficit produced by adrenal demedullation. Further, intra-amygdala injections of propranolol (0.2 microgram) blocked the enhancing effect, on retention, of posttraining s.c. injections of epinephrine. These findings suggest that activation of noradrenergic receptors in the amygdala may be involved in memory processing and may play a role in the memory-modulating effect of peripheral epinephrine. 相似文献
143.
144.
The action of papain and bromelain, prepared over a pH range from 4.6 to 8.6, was evaluated for the ability to render red cells agglutinable by five incomplete antibodies of differing blood group specificities using a two-stage technique. The optimal pH for treatment of red cells by activated papain or bromelain was between 5.4 and 5.8. Above this pH range, a fall in serological sensitivity was apparent which was much more pronounced with papain than with bromelain. The optimal pH for enzyme treatment of red cells can be achieved in two-stage techniques, but not in one-stage techniques due to the buffering effect of serum proteins. 相似文献
145.
Katherine A Hillman Tanya M Johnson Paul J D Winyard Geoffrey Burnstock Robert J Unwin Adrian S Woolf 《Experimental nephrology》2002,10(1):34-42
BACKGROUND: Purinergic receptors are cell-surface molecules that bind extracellular nucleotides, notably ATP. The P2X family includes seven nonselective ion channels with one member, P2X(7), implicated in cytolytic pore formation and cell death. MATERIALS AND METHODS: We sought P2X(7) expression in mouse nephrogenesis and cpk/cpk renal cyst growth, conditions in which both proliferation and apoptosis are prominent. RESULTS: P2X(7) immunolocalized to condensed metanephric mesenchyme: both proliferation and apoptosis were detected in this compartment, assessed by proliferating cell nuclear antigen expression and propidium iodide-stained pyknotic nuclei respectively. Later in nephrogenesis, P2X(7) was detected in collecting ducts, a pattern persisting to maturity. A mesenchymal to epithelial shift of P2X(7) expression was also documented in ureter development. In cpk/cpk kidneys, P2X(7)-expressing collecting duct cysts dominated histology from two weeks until four weeks after birth, when animals die from uremia. In polycystic kidneys pyknotic nuclei were rarely identified in P2X(7)-expressing epithelia, but were detected between cysts, consistent with a non-apoptotic role for P2X(7) in cyst enlargement. CONCLUSION: P2X(7) is expressed during normal nephrogenesis and in a model of congenital polycystic kidney disease. Further experiments are necessary to define possible functions of P2X(7) in these settings. 相似文献
146.
147.
148.
W F Rayburn M Z Johnson K L Hoffman S M Donn R M Nelson 《American journal of perinatology》1987,4(2):98-101
A goal for the obstetrician and neonatologist is to screen for risk factors associated with intraventricular hemorrhage (IVH) in the low-birthweight infant. Perinatal events that lead to neonatal metabolic and cardiovascular derangements seem to provoke IVH, and conflicting reports have implicated labor as being contributory. A fetal heart rate (FHR) abnormality during premature labor may be a predictor of subsequent neonatal IVH. For this reason, 5 years of FHR tracings at two university medical centers were reviewed for inborn infants who were delivered after premature labor and weighed less than or equal to 2000 gm. Sixty-four infants developed IVH, but pre-existing labor with a discernible FHR pattern was recorded in only 38 (59%) cases. Interpretations were reassuring in 17 (45%) cases, suspicious in 7 (18%) cases, and ominous in 14 (37%) cases. This proportion of FHR patterns was not significantly different from a matched group of premature infants without IVH during the same period. Interpretations of intrapartum FHR patterns of low-birthweight infants are limited, especially before 30 weeks gestation, and not useful in predicting neonatal IVH. 相似文献
149.
Scott A Fields Elizabeth Morrison Ernie Yoder Kevin Krane Thomas Agresta Rich Esham Frederick McCurdy Jonathan Rosen James Shumway 《Academic medicine》2002,77(6):543-546
PURPOSE: Chart notes are used to support billing codes under the evaluation and management guidelines of the Health Care Financing Administration (HCFA), in addition to serving as a record of the visit. To better understand the effect of the HCFA documentation guidelines, the authors collected data on how the guidelines affect participation by university- and community-based faculty in clinical education programs. METHOD: In 2000, the authors sent six copies of their questionnaire to the associate deans of the 125 U.S. medical schools and requested they distribute them to all core clerkship directors. The questionnaire consisted of multiple-choice and short-answer questions regarding documentation of medical visits, participation of community-based faculty, understanding of HCFA documentation guidelines, and effects on education programs. RESULTS: The response rate was about 50%. Most of the 379 clerkship directors who responded (77%) stated they were aware the HCFA documentation guidelines include specifications regarding the role medical students can play and documentation of medical visits, and 64% indicated they were concerned the guidelines would affect their educational programs. Concerns included the loss of student independence and active participation in the patient care environment (37), time constraints and the changing balance between education and service (16), loss of faculty and decreased morale (11), and decreased quality of care for patients (7). CONCLUSION: Leaders of medical education must work to modify these guidelines to protect the quality of patients' care, while maximizing students' educational opportunity and participation. 相似文献
150.
Naiquan Zheng Rafael F Escamilla Glenn S Fleisig Kevin E Wilk James R Andrews 《中华骨科杂志》2002,29(1):697-700
结果 髌股关节的压力与应力随膝关节屈曲角度的增加而升高,随膝关节屈曲角度的减小而降低(图3~8).不同膝关节屈曲角度下弓步变化和跨步变化的髌股关节压力见表1. 相似文献