首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3211篇
  免费   192篇
  国内免费   7篇
耳鼻咽喉   23篇
儿科学   99篇
妇产科学   127篇
基础医学   455篇
口腔科学   34篇
临床医学   457篇
内科学   592篇
皮肤病学   88篇
神经病学   325篇
特种医学   49篇
外科学   342篇
综合类   33篇
一般理论   2篇
预防医学   431篇
眼科学   40篇
药学   155篇
中国医学   1篇
肿瘤学   157篇
  2024年   6篇
  2023年   52篇
  2022年   76篇
  2021年   150篇
  2020年   89篇
  2019年   142篇
  2018年   154篇
  2017年   90篇
  2016年   111篇
  2015年   105篇
  2014年   153篇
  2013年   170篇
  2012年   269篇
  2011年   269篇
  2010年   122篇
  2009年   113篇
  2008年   187篇
  2007年   205篇
  2006年   209篇
  2005年   180篇
  2004年   147篇
  2003年   123篇
  2002年   125篇
  2001年   17篇
  2000年   10篇
  1999年   8篇
  1998年   12篇
  1997年   13篇
  1996年   7篇
  1995年   9篇
  1994年   9篇
  1993年   10篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1989年   5篇
  1988年   7篇
  1987年   2篇
  1986年   5篇
  1985年   2篇
  1984年   2篇
  1983年   6篇
  1982年   4篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1977年   3篇
  1960年   1篇
  1958年   1篇
  1894年   1篇
排序方式: 共有3410条查询结果,搜索用时 0 毫秒
991.
CONTEXT: Age-associated hypogonadism (testosterone deficit) occurs in 30% of men after the age of 55; it is associated with decreased muscle mass, bone mineral density, and libido, and with anorexia, fatigue, and irritability. Although some of these symptoms overlap with those of depression, the association between the 2 disorders is unclear. OBJECTIVE: To determine if hypogonadal men have an increased incidence of depressive illness compared with eugonadal men. DESIGN: Historical cohort study using computerized medical records, followed by a manual medical record review. SETTING: Veterans Affairs Puget Sound Health Care System. PARTICIPANTS: Two hundred seventy-eight men 45 years and older, without prior diagnosed depressive illness and with consistently normal or low testosterone levels (total testosterone level < or =200 ng/dL [< or =6.94 nmol/L]; or free testosterone level < or =0.9 ng/dL [< or =0.03 nmol/L]) at baseline and during a 2-year follow-up period. MAIN OUTCOME MEASURES: Incidence of, and time to, a depression diagnosis. RESULTS: The 2-year incidence of diagnosed depressive illness was 21.7% in hypogonadal men vs 7.1% in others (chi2(1)=6.0, P=.01). A Kaplan-Meier survival analysis showed a significant difference between hypogonadal and eugonadal men in time to diagnosed depression (log-rank test chi2(1)=6.9, P=.008). We used Cox proportional hazards regression models to examine the association of hypogonadism and time to depression diagnosis, adjusting for age, race, number of clinic visits, alcohol use disorders, prostate cancer, and overall medical comorbidity. The unadjusted hazard ratio for depression with hypogonadism was 3.5 (95% confidence interval, 1.3-9.4) (P=.01). Controlling for all covariates, hypogonadism remained significantly associated with depression (adjusted hazard ratio, 4.2; 95% confidence interval, 1.5-12.0) (P=.008). CONCLUSIONS: Hypogonadal men showed an increased incidence of depressive illness and a shorter time to diagnosis of depression. Further prospective studies are needed to confirm these preliminary findings and to clarify the role of testosterone in the treatment of depressive illness in older men.  相似文献   
992.
Neurophysiological studies have characterized the sensory responses of primary afferent nociceptors that innervate the intracranial dura. The present study used anatomical methods to examine in greater detail the axonal trajectories within the dura, as well as the axonal size distribution of the dural innervation. Immunostaining for CGRP in dural wholemounts revealed a network of fibers extending across the entire dura, with an especially dense plexus running along the borders of the transverse and superior sagittal sinuses. The plexus along the caudal border of the transverse sinus partially overlapped the dural area that shows the greatest density of mast cells. Visualization of axon bundles by DiI application in formalin-fixed tissue revealed two separate systems of fibers in the dura that could be distinguished by the orientation of their trajectories: one that runs parallel to the middle meningeal artery (MMA), and another with a more or less orthogonal orientation that runs rostromedially from the transverse sinus across the MMA. Axons traversed large distances across the dura, but the majority of the branching and arborization was usually concentrated in the distal part of the trajectory. In separate animals, measurement of myelinated axon diameters with electron microscopy showed that approximately one-third of the myelinated axons in the nerves supplying the dura (nervus spinosus and tentorial nerves) could be classified as A-beta, since they were comparable in size to the majority of axons in the trochlear nerve and the upper end of the size range in the trigeminal nerve (i.e., > 5 microm).  相似文献   
993.
OBJECTIVE: To examine the contribution of perceived importance of activities of daily living (ADL) to arthritis-specific helplessness in a sample of rheumatoid arthritis (RA) patients over a 1-year period. METHOD: Forty-two individuals from an outpatient rheumatology clinic completed measures of ADL importance, helplessness, depression, pain, and disability; the physician's assistant provided objective ratings of disability. RESULTS: Time 1 importance of ADL predicted a significant amount of variance in Time 2 arthritis helplessness after statistically controlling disease and psychological covariates. Moreover, increased perceived ADL importance predicted decreased arthritis helplessness over the 1-year period. CONCLUSIONS: Results indicate that RA patients' experience of arthritis-specific helplessness may be minimized over time when performing ADL is perceived as important. Furthermore, these findings provide preliminary evidence for one possible antecedent to increased perceptions of arthritis helplessness in individuals with RA.  相似文献   
994.
Large-scale investment in health care information technology (IT) infrastructure will not take place without leadership by the federal government. But how the federal government supports the financing of health care IT is critical. Health care IT development has multiple aspects, but it is fundamentally a problem of community infrastructure development. A policy approach that has had consistent success in financing our country's essential physical infrastructure in transportation and environmental protection will be well suited to fostering health care IT infrastructure as well. We propose the creation of a health care IT revolving loan fund program to invest public dollars in health care IT infrastructure projects through community-level nonprofit lending agencies.  相似文献   
995.
Broderick M 《RN》2003,66(9):48-53
  相似文献   
996.
OBJECTIVE: To determine whether an algorithm for the treatment of attention-deficit/hyperactivity disorder (ADHD) can be implemented in a community mental health center. METHOD: Fifty child and adolescent patients at Texas community mental health centers who met criteria for ADHD were treated according to an algorithm-based disease management program for ADHD. Psychiatrists were trained in the use of the algorithm, and each subject underwent a baseline assessment consisting of a structured interview and standardized rating scales. Subjects were monitored for 4 months. At the end of treatment, the psychiatrists completed the Clinical Global Impression Scale (CGI) and the baseline rating scales were repeated. The primary variables of interest were psychiatrist and family adherence to the algorithm. To examine impact on treatment outcome, the CGI of the algorithm subjects was compared with CGIs based on chart reviews of 118 historical controls. RESULTS: Psychiatrists implemented the major aspects of the algorithm, but the detailed tactics of the algorithm (use of fixed titration of stimulants) were less well adhered to. CONCLUSIONS: An algorithm for the treatment of ADHD can be implemented in a community mental health center.  相似文献   
997.
BACKGROUND: Outpatient knee surgery has come to involve increasingly complex procedures. The authors present observational data from a nerve block algorithm designed for the care of outpatients undergoing knee surgery. The aim of this report is to demonstrate differences in pain and unplanned hospital admission associated with surgical complexity and nerve blocks used. METHODS: Day-of-surgery outcomes were studied for 1,200 consecutive outpatients undergoing routine arthroscopy or one of six complex outpatient knee procedures. Nerve blocks were administered on the basis of anticipated pain from open incisions in the femoral and sciatic nerve distributions. Regression analysis was used to determine factors associated with postoperative pain and unplanned hospital admissions, and patients were categorized as having received femoral and sciatic nerve blocks (FSB), femoral nerve block only (FNB), or no nerve blocks. RESULTS: Patients undergoing more complex (vs. less invasive) knee surgery were at greater risk for pain (P 相似文献   
998.
Synaptic plasticity is important for formation of long-term memories and in re-establishment of function following injury. Seven cDNAs enriched following lesion in the hippocampus of the rat have been isolated using a PCR-based cDNA suppression subtraction hybridization. Sequence analysis resulted in the identification of two genes with known roles in synaptic development and neuronal activities: astrotactin and calcineurin. These two neuron-specific genes have established roles in development or synaptogenesis. Sequence analysis of the other five additional genes shows that two are likely to be involved in G-protein signaling pathways, one is a WD repeat protein, and the remaining two are entirely novel. All seven candidates are expressed in the hippocampus and, in some cases, cortical layers of adult brains. RT-PCR data show that expression increases following synaptogenic lesion. Immunocytochemical analysis in primary hippocampal neurons showed that Calcineurin immunoreactivity was redistributed in neurons during 2 weeks in culture. This redistribution suggests that Calcineurin's role changes during neurite outgrowth immediately prior to synapse formation in vitro. In addition, inhibiting Calcineurin activity with cyclosporin A enhanced neurite outgrowth, suggesting that Calcineurin has a regulatory role in axon sprouting. The discovery of previously unknown genes involved in the response to neurodegeneration will contribute to our understanding of neural development, responses to CNS trauma, and neurodegenerative diseases.  相似文献   
999.
1000.
Brush Wellman, the world's leading producer and supplier of beryllium products, has systematically hidden cases of beryllium disease that occurred below the threshold limit value (TLV) and lied about the efficacy of the TLV in published papers, lectures, reports to government agencies, and instructional materials prepared for customers and workers. Hypocritically, Brush Wellman instituted a zero exposure standard for corporate executives while workers and customers were told the 2 microgram standard was "safe." Brush intentionally used its workers as "canaries for the plant," and referred to them as such. Internal documents and corporate depositions indicate that these actions were intentional and that the motive was money. Despite knowledge of the inadequacy of the TLV, Brush has successfully used it as a defense against lawsuits brought by injured workers and as a sales device to provide reassurance to customers. Brush's policy has reaped an untold number of victims and resulted in mass distribution of beryllium in consumer products. Such corporate malfeasance is perpetuated by the current market system, which is controlled by an organized oligopoly that creates an incentive for the neglect of worker health and safety in favor of externalizing costs to victimized workers, their families, and society at large.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号