全文获取类型
收费全文 | 91890篇 |
免费 | 7593篇 |
国内免费 | 231篇 |
专业分类
耳鼻咽喉 | 899篇 |
儿科学 | 2793篇 |
妇产科学 | 2255篇 |
基础医学 | 12454篇 |
口腔科学 | 1625篇 |
临床医学 | 10272篇 |
内科学 | 18301篇 |
皮肤病学 | 1558篇 |
神经病学 | 10388篇 |
特种医学 | 3066篇 |
外国民族医学 | 4篇 |
外科学 | 10420篇 |
综合类 | 1126篇 |
一般理论 | 92篇 |
预防医学 | 9970篇 |
眼科学 | 1787篇 |
药学 | 6062篇 |
2篇 | |
中国医学 | 139篇 |
肿瘤学 | 6501篇 |
出版年
2023年 | 783篇 |
2022年 | 1306篇 |
2021年 | 2704篇 |
2020年 | 1601篇 |
2019年 | 2309篇 |
2018年 | 2663篇 |
2017年 | 1895篇 |
2016年 | 2053篇 |
2015年 | 2280篇 |
2014年 | 2870篇 |
2013年 | 3986篇 |
2012年 | 6089篇 |
2011年 | 6151篇 |
2010年 | 3212篇 |
2009年 | 2831篇 |
2008年 | 4732篇 |
2007年 | 4913篇 |
2006年 | 4689篇 |
2005年 | 4369篇 |
2004年 | 4044篇 |
2003年 | 3684篇 |
2002年 | 3416篇 |
2001年 | 1711篇 |
2000年 | 1691篇 |
1999年 | 1570篇 |
1998年 | 865篇 |
1997年 | 750篇 |
1996年 | 681篇 |
1995年 | 626篇 |
1994年 | 518篇 |
1993年 | 459篇 |
1992年 | 1221篇 |
1991年 | 1228篇 |
1990年 | 1145篇 |
1989年 | 1141篇 |
1988年 | 949篇 |
1987年 | 1062篇 |
1986年 | 987篇 |
1985年 | 991篇 |
1984年 | 804篇 |
1983年 | 659篇 |
1982年 | 423篇 |
1981年 | 405篇 |
1979年 | 716篇 |
1978年 | 535篇 |
1977年 | 464篇 |
1976年 | 464篇 |
1975年 | 403篇 |
1974年 | 524篇 |
1973年 | 463篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
A. O. Azghani J. W. Baker S. Shetty E. J. Miller G. J. Bhat 《Inflammation research》2002,51(10):506-510
OBJECTIVE AND DESIGN: Bacterial products as well as the host airway inflammatory responses contribute to the pathogenesis of Pseudomonas infections. We sought to determine if Pseudomonas elastase (PE) induces mitogen-activated protein (MAP) kinase activity in association with interleukin-8 (IL-8) production by alveolar epithelial cells. METHODS: We utilized Western blot analysis to detect phosphorylation of signaling intermediates and ELISA was used to measure IL-8 production. RESULTS: We found that PE induces phosphorylation of the extracellular signal-regulated (ERK1/2) proteins of the MAPK pathway in A549 epithelial cells. Similar results were obtained using primary cultures of rabbit alveolar type II epithelial cells. PE also enhanced IL-8 production, which was abolished in the presence of the ERK activation inhibitor U0126. CONCLUSIONS: We conclude that PE activates the ERK1/2 arm of the MAPK pathway and that activation of this pathway results in enhanced IL-8 production. The results demonstrate that PE may augment pulmonary inflammation via cellular signaling that regulates expression of IL-8. 相似文献
72.
Humoral and cellular immunity following severe head injury: review and current investigations. 总被引:9,自引:0,他引:9
Infection is a common and serious complication of severe head injury. Immunocompetence in 25 severely head injured patients was investigated by measuring: (1) delayed-type hypersensitivity (DTH) skin test responses to common antigens; (2) phytohaemagglutinin (PHA) stimulated peripheral blood lymphocyte (PBL): blastogenesis, phenotype expression, and lymphokine production; (3) lymphokine-activated killer (LAK) cytotoxicity, antibody dependent cellular cytotoxicity (ADCC) and natural killer (NK) cytotoxicity; and (4) immunoglobulin and complement levels. The incidence of anergy to DTH skin testing was 100%. There was a decrease in PHA stimulated: PBL blastogenesis (p = 0.002), T-cell expression (p = 0.018), helper T-cell expression (p less than 0.001), interleukin-2 receptor expression (p less than 0.001), interleukin-2 production (p = 0.035) and gamma-interferon production (p less than 0.001). LAK cytotoxicity was depressed following incubation with IL-2 (p less than 0.001). There was no significant decrease in immunoglobulin levels and all acute phase reactants tested increased. The results of this study indicate that the cellular arm of immune response, including lymphocyte activation and cytokine production, is suppressed following severe head injury. The lack of enhancement in LAK cytotoxicity following incubation of PBLs with interleukin-2 suggests that factors other than decreased interleukin-2 production, such as the inherent lymphocyte dysfunction, other soluble mediators or suppressor cells, may be responsible for the reduction in cellular immunity observed following severe head injury. 相似文献
73.
Michael K. Gardner Elaine Clark Mary Ann C. Bowman Patrick J. Miller 《Alcoholism, clinical and experimental research》1989,13(4):508-511
This study investigated analogical reasoning abilities of alcoholics who had been abstinent from alcohol for at least 1 year. Their performance was compared to that of nonalcoholic controls matched as a group for education, age, and gender. Solution times and error rates were modeled using a regression model. Results showed a nonsignificant trend for alcoholics to be faster, but more error prone, than controls. The same componential model applied to both groups, and fit them equally well. Although differences have been found in analogical reasoning ability between controls and alcoholics immediately following detoxification, we find no evidence of differences after extended periods of sobriety. 相似文献
74.
A retrospective analysis of the results of 27,801 cervical smears from one year in a community laboratory was undertaken. This represented 23,820 individual patients. Abnormalities were seen in 9.3% of patients. Three point seven percent of patients had benign abnormalities, 5.5% had cervical intraepithelial neoplasia and 0.1% had major abnormalities. The incidence of cervical epithelial abnormality was highest in the 15-34 age group but major abnormalities were seen most often in the 55+ age group. Human papillomavirus was more commonly seen in the youngest age group. The presence of inflammation was reported in 65% of the smears. Thirty percent of smears had no endocervical cells and 0.6% were grossly inadequate. Fifteen percent of patients had repeat smears and 3% of total smears were judged unnecessary. Forty two point six percent of patients less than 55 years of age in the laboratory population base had a smear but only 7.9% of those over 55. 相似文献
75.
Nursing diagnosis as a critical component of the nursing process provides a common taxonomy to describe problems that nurses can treat and is a convenient, logical way to reference nursing standards. Theory is translated into practice with the use of population-specific prototype care guides and a written orders system. Nurses in leadership are responsible for providing the necessary resources to promote professional growth and facilitate desired change. Recommendations to assist with the implementation of nursing diagnosis are identified in Table 1. The system is dependent on staff nurses' professional commitment to learning and willingness to actively participate in change. Involvement of staff nurses continues to be a critical factor in the improvement of nursing practice. 相似文献
76.
Previous studies have shown that stimulation of adrenergic receptors in the brain increases the expression of the immediate early gene (IEG), c-fos, in vivo (Mol. Brain Res., 6(1989) 39-45). The present study was undertaken to determine whether this also holds for other IEGs which have been shown to be activated in brain cell culture by adrenergic agonists. Both yohimbine injection and stressful stimulation, two treatments causing brain norepinephrine (NE) release, were found to cause a parallel, transient activation of at least 5 IEGs (c-fos, nur77, tis-7, zif-268 and tis-21) in the rat cortex. Genes that are not immediate early (beta-actin, NGF and HSP70) were found not to be affected in the interval used (6 h). The responses were mediated predominantly by beta-adrenoceptors with some contribution from alpha 1 receptors. The parallel activation of multiple genes by noradrenergic receptors may enable the coding of different biochemical responses to the activation of different receptors. 相似文献
77.
78.
The family physician should follow the small premature infant in the neonatal intensive care center and review the baby's problems and risk factors. In the office, special attention is required in monitoring the infant. Proper hospital and office care greatly improve the prognosis. 相似文献
79.
Cocaine-treated rats acquired a preference for cocaine-associated contextual stimuli (CS) relative to saline-injected control rats. However, when animals were given repeated tests for conditioned place preference intermittent between conditioning trials, they displayed an attenuation in strength of conditioning. This attenuation was not due to pharmacologic tolerance (Experiment 1), but rather reflected a disruption in learning due to exposure to the CS alone (Experiment 2). Like other examples of classical conditioning, the strength of the conditioned response (CR) as assessed by the conditioned place preference model may be influenced by partial reinforcement. 相似文献
80.
Distance learning in a school nurse credential program. 总被引:4,自引:0,他引:4
Distance learning, which encompasses many methodologies, is becoming a more readily available educational alternative. Because there are a limited number of school nurse credential programs and the demand for school nurses is increasing, distance learning may be a viable method of instruction. This article describes the authors' experiences organizing and presenting distance learning courses to five remote sites for students in a university school nurse credential program. After numerous inquiries, potential students from several areas were surveyed, and arrangements were made with universities in those areas to receive two-way audio and video transmissions of two seminar courses; later, two clinically oriented courses in the school nurse program. Students were able to complete their program requirements by taking equivalent course work at their local universities. Perceptions of students and the instructor, course evaluation, and practical suggestions are shared. Guidelines for potential students about selecting quality distance education programs are also noted. 相似文献