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   4038篇
  免费   256篇
  国内免费   33篇
耳鼻咽喉   27篇
儿科学   132篇
妇产科学   89篇
基础医学   533篇
口腔科学   59篇
临床医学   506篇
内科学   708篇
皮肤病学   60篇
神经病学   386篇
特种医学   64篇
外科学   467篇
综合类   39篇
一般理论   4篇
预防医学   603篇
眼科学   41篇
药学   268篇
中国医学   3篇
肿瘤学   338篇
  2023年   29篇
  2022年   42篇
  2021年   108篇
  2020年   53篇
  2019年   96篇
  2018年   100篇
  2017年   64篇
  2016年   83篇
  2015年   80篇
  2014年   131篇
  2013年   199篇
  2012年   285篇
  2011年   335篇
  2010年   140篇
  2009年   131篇
  2008年   255篇
  2007年   283篇
  2006年   279篇
  2005年   215篇
  2004年   241篇
  2003年   193篇
  2002年   170篇
  2001年   61篇
  2000年   41篇
  1999年   48篇
  1998年   43篇
  1997年   35篇
  1996年   34篇
  1995年   36篇
  1994年   22篇
  1993年   27篇
  1992年   43篇
  1991年   35篇
  1990年   38篇
  1989年   19篇
  1988年   21篇
  1987年   28篇
  1986年   16篇
  1985年   16篇
  1984年   19篇
  1982年   17篇
  1980年   14篇
  1979年   18篇
  1978年   27篇
  1977年   9篇
  1976年   10篇
  1975年   13篇
  1974年   19篇
  1973年   10篇
  1970年   9篇
排序方式: 共有4327条查询结果,搜索用时 15 毫秒
1.
The normal function of the hypothalamic-pituitary-adrenal (HPA) axis, and resultant glucocorticoid (GC) secretion, is essential for human health. Disruption of GC regulation is associated with pathologic, psychological, and physiological disease states such as depression, post-traumatic stress disorder, hypertension, diabetes, and osteopenia, among others. As such, understanding the mechanisms by which HPA output is tightly regulated in its responses to environmental stressors and circadian cues has been an active area of investigation for decades. Over the last 20 years, however, advances in gene targeting and genome modification in rodent models have allowed the detailed dissection of roles for key molecular mediators and brain regions responsible for this control in vivo to emerge. Here, we summarize work done to elucidate the function of critical neuropeptide systems, GC-signaling targets, and inflammation-associated pathways in HPA axis regulation and behavior, and highlight areas for future investigation.  相似文献   
2.
3.
Aim: We performed a semiprospective and retrospective review of all admissions to a single institution of systemic lupus erythematosus (SLE) patients, admitted due to active disease. The aim was to describe differences in disease activity as a cause of hospital admissions between patients originating from South‐East Asia/China (SAC) and Caucasians. Method: There were 210 patients admitted for active disease, with a total of 567 admissions for active SLE over a 16‐year period. Allowing for patients who had left our database, there was a total of 3415 patient years of observation. Results: Patients from SAC with a flare requiring admission presented earlier in their disease course and with more active disease than did Caucasians (median SLE Disease Activity Index 13 vs. 8, P= 0.002). They had longer inpatient stays (7 vs. 5 days P = 0.03). There was a trend to higher rates of re‐presentation to hospital for flare (59% in SAC patients vs. 41% in Caucasians, P = 0.09) with more subsequent admissions (3 vs. 2 P = 0.06) despite a shorter period of observation. Conclusions: South‐East Asian/Chinese were more likely to be diagnosed with class III/IV glomerulonephritis and require cyclophosphamide both at presentation and subsequent admissions. More patients from SAC were readmitted to hospital for severe central nervous system disease after their first hospital admission. In this population, lupus patients had more severe flares and more frequently required admission for these than Caucasians.  相似文献   
4.
Group mean Schistosoma mansoni reinfection patterns are presented for 2 years after treatment with oxamniquine in 1981 of over 100 9- to 16-year-old Kenyan schoolchildren, and for one year after retreatment in 1983 with either oxamniquine or praziquantel when most (nearly 700) infected people in the whole community were treated. Quality control confirmed comparable Kato egg counts throughout the study. Continuing transmission after 1981 raised prevalence to nearly its original level within 6 months, but intensity remained suppressed throughout the 2 year follow-up and very few children reacquired heavy infections (greater than 400 eggs/g). Age and sex had significant effects: reinfection diminished with age, especially among boys--a pattern not apparently attributable to differential water contact. Children with heavy pretreatment infections tended to develop heavy reinfections but this trend was not statistically significant on a group basis, nor were similar trends during the period of less pronounced transmission following the 1983 community treatment. Oxamniquine was equally effective in children receiving it in both 1981 and 1983, and the efficacy of praziquantel resembled that of oxamniquine. In this area of Kenya, repeated chemotherapy will be needed to contain transmission, probably annually or biennially, unless supplemented with other, effective control measures. These findings confirm the beneficial effects of treating even a limited segment of a community at intervals of a year or more without necessarily stopping transmission. They are also compatible with recent findings on potential immune mechanisms in man.  相似文献   
5.
Hurricanes Katrina and Rita forced many individuals along the coast of Texas and Louisiana to seek shelter inland. Among the evacuees were residents with special needs and residents of nursing homes and group homes caring for mentally retarded and physically disabled persons. Many nurses volunteered to provide health care for those in need. This article discusses challenges and opportunities that were encountered by nurses volunteering in special-needs shelters. Issues related to human and physical resources, patient care, and confidentiality are discussed including lessons learned. As nurses who cared for evacuees in the shelter, it is hoped some of the lessons learned can be utilized in future disasters.  相似文献   
6.
Gallstones are common and their incidence increases with age.1 Fifty per cent of these stones are in the common bile duct (CBD) in the elderly.2 Most of them are silent but with time there is an increasing chance of developing symptoms which are more likely to be serious in the elderly.3 Failure to relieve mechanical obstruction of bile flow may lead to secondary biliary cirrhosis.4 It has been estimated that on average secondary biliary cirrhosis develops some seven years after the onset of obstruction from a stricture, four and half years after gallstone obstruction and 10 months after the onset of malignant stricture.5 The characteristic features are the pathological findings of portal-portal linkages, with a pattern of monolobular cirrhosis and the preservation of normal vascular relationships.6 Secondary biliary cirrhosis may lead to hepatic insufficiency and portal hypertension with the resultant complications, such as bleeding oesophageal varices, hypersplenism with pancytopenia, ascites and encephalopathy. We describe a patient in whom the diagnosis was not suspected until laparotomy and confirmed only at autopsy.  相似文献   
7.
Depressive symptoms in older adults are common, but the minority of elderly meet criteria for major depressive disorder. This has led to confusion regarding the recognition of diagnosis, approach to treatment, and monitoring of outcomes in this needy population. Few depressed older adults are willing to seek treatment from psychiatrists or mental health specialists. Treatment approaches to the depressive spectrum of disorders in late life, which encompasses major and minor depressive disorder, dysthymic disorder, and mood disorders related to medical conditions, must include evidence-based algorithms that can be delivered in a variety of health care settings. Several recent multisite trials have advanced the use of collaborative care models and the systematic stepwise approach to the treatment of depression and anxiety states in older adults. This offers the ability to provide effective treatment of depression for older adults, consistent with current guidelines, in primary care and specialized health care settings.  相似文献   
8.
Sham in CAM     
Several unique methodological challenges exist concerning the choice of the most appropriate comparator or control group for clinical research in complementary and alternative medicine (CAM). This article reviews the four major types of control groups (active control, placebo or sham, no intervention control, and different protocols of the experimental intervention), noting the different questions they answer and the different contexts in which they may be used, and discusses how this framework may be applied to CAM research in an effort to avoid methodologically flawed study designs. The choice of comparator depends on complex factors such as the research question being asked, the most plausible competing rival hypotheses, and logistical considerations related to ethics, methodology and feasibility. For example, for sham to be an effective comparator it must capture the ‘nonspecific’ elements of the treatment without containing those that are ‘specific’ to the research question at hand. However, as demonstrated by the examples of acupuncture and energy medicine, designing such sham intervention is not always easy. Controlling for social interaction between practitioners and subjects, addressing issues around ethics, having good-quality measurement of treatment integrity and intensity, and selecting practitioners of sufficient competence when doing a sham process are other important parts of correct design choices. In the light of these complexities, clinicians and researchers alike need a better match between the research questions and the design employed in order for their research to be both scientifically valid and clinically meaningful.  相似文献   
9.
Advances in science have increased the knowledge of how cells die in the body (apoptosis). A basic understanding of this process can improve nurses' ability to review new scientific literature and enable them to provide safer bedside care.  相似文献   
10.
Cerebral Emboli during Cardiac Surgery in Children   总被引:7,自引:0,他引:7  
Background: Microemboli occur commonly during cardiac surgery in adults, and, when present, increase the risk of neuropsychological deficits. Their incidence and significance during correction of congenital heart disease is unknown. The authors hypothesized that microemboli would occur before bypass with right-to-left cardiac shunts and would also occur in large numbers when the aortic crossclamp was released in children during repair of congenital heart defects.

Methods: In 25 children studied with carotid artery Doppler, embolic signals were counted and timed in relation to 13 intraoperative events. Patients were classified as either at high risk (obligate right-to-left shunt or uncorrected transposition of the great arteries) or at low risk (net left-to-right shunt or simple obstructive lesions) for paradoxical (venous to arterial) emboli.

Results: The median number of emboli detected was 122 (range, 2-2,664). Forty-two percent of all emboli were detected within 3 min of release of the aortic crossclamp. The high-risk group had significantly more emboli (median, 66; range, 0-116) during the time interval before cardiopulmonary bypass than did the low-risk group (median, 8; range, 0-73), with P < 0.01. There was no significant difference between the high-and low-risk groups in the total number of emboli detected. There was no apparent association between number of emboli and gross neurologic deficits.  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