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   33073篇
  免费   1814篇
  国内免费   146篇
耳鼻咽喉   350篇
儿科学   733篇
妇产科学   574篇
基础医学   6277篇
口腔科学   739篇
临床医学   2625篇
内科学   6256篇
皮肤病学   857篇
神经病学   3411篇
特种医学   1428篇
外科学   4619篇
综合类   153篇
一般理论   14篇
预防医学   1653篇
眼科学   721篇
药学   2315篇
中国医学   21篇
肿瘤学   2287篇
  2021年   347篇
  2020年   297篇
  2019年   489篇
  2018年   571篇
  2017年   438篇
  2016年   567篇
  2015年   655篇
  2014年   783篇
  2013年   1174篇
  2012年   1636篇
  2011年   1752篇
  2010年   1181篇
  2009年   1130篇
  2008年   1897篇
  2007年   1929篇
  2006年   1797篇
  2005年   1923篇
  2004年   1797篇
  2003年   1764篇
  2002年   1847篇
  2001年   344篇
  2000年   274篇
  1999年   392篇
  1998年   502篇
  1997年   413篇
  1996年   368篇
  1995年   337篇
  1994年   289篇
  1993年   258篇
  1992年   212篇
  1991年   204篇
  1990年   171篇
  1989年   161篇
  1988年   171篇
  1987年   135篇
  1985年   157篇
  1984年   181篇
  1983年   161篇
  1982年   198篇
  1981年   169篇
  1978年   135篇
  1933年   170篇
  1932年   180篇
  1931年   167篇
  1930年   169篇
  1929年   147篇
  1928年   163篇
  1927年   144篇
  1926年   158篇
  1925年   139篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.

Background  

The aims of this study were to examine the extent to which higher intellectual abilities protect higher socio-economic groups from functional decline and to examine whether the contribution of intellectual abilities is independent of childhood deprivation and low birth weight and other socio-economic and developmental factors in early life.  相似文献   
72.
73.
OBJECTIVE: Previous studies have shown that decorin and biglycan account for over 70% of the proteoglycans (PGs) synthesized by human peritoneal mesothelial cells (HPMCs). Since these PGs are involved in the control of cell growth, cell differentiation, and matrix assembly, we investigated their turnover in cultured HPMCs. METHODS: Confluent HPMCs were metabolically labeled with [35S]-sulfate and the labeled products isolated from the cell medium and the cell layer characterized by sensitivity to bacterial eliminases. Experiments were undertaken with exogenous labeled decorin, and its metabolic state was studied. RESULTS: In a 24-hour labeling period, 75% of the newly synthesized chondroitin sulfate/dermatan sulfate (CS/DS) PGs appeared in the culture medium, the majority of which (90%) was decorin. In the cell layer, protein-free glycosaminoglycan (GAG) chains accounted for 21% of the total CS/DS at 24 hours and exhibited constant specific activity at 12-16 hours. The latter material was turned over with a half-life of approximately 2.5 hours. Exogenous decorin underwent receptor-mediated endocytosis and subsequent intracellular degradation. Uptake but not degradation could be inhibited by heparin. CONCLUSIONS: HPMCs are distinguished by a rapid turnover of decorin. A characteristic metabolic feature is the existence of a large intracellular pool of protein-free DS-GAGs. Understanding the control of decorin turnover in HPMCs might lead to delineation of its potential role in both the physiology and pathophysiology of the membrane in PD patients.  相似文献   
74.
75.
The elderly account for an ever-increasing proportion of emergency department patients. Demographic data show that the population which is 80 years of age or older will be further increasing in coming years. Due to this fact we sought the reasons of using of the emergency department by elderly patients (≥80 years), admitted by ambulance service, and to analyse the general management of this collective according to a younger comparison group. We used the data from a prospective registry, in which all consecutive patients admitted to the emergency department by ambulance service were included, to process this retrospective analysis. In this registry, diagnosis (in the ICD-10 classification), age, sex, and inpatient/outpatient treatment were documented. In addition further management, intensive care treatment, and outcome during emergency department stay were registered. The patients were stratified by age into two groups (< 80 years; ≥80 years). The observation period lasted from January 1, 2005 to December 31, 2005. During the study 6590 patients were observed of whom 5670 patients (86.0%) were under 80 years (PG<80) and 920 (14.0%) were 80 years of age or older (PG≥80). Comparing inpatient treatment (PG<80: 40.1%; PG≥80: 39.8%) vs outpatient treatment (PG<80: 59.9%; PG≥80: 60.2%) no significant difference between both groups was registered. In comparing the ICD- 10 main diagnosis categories, no relevant difference could be ascertained. By contrast a significantly higher mortality (3.0% vs 1.6%; p≤0.01) in the emergency department was shown within the PG≥80, especially if the diagnosis was myocardial infarction or stroke. The most frequent discharge diagnosis in the PG≥80 was acute myocardial infarction (6.7%). A percutaneous coronary intervention and artificial respiration was less frequently used in the elderly group. Patients beyond 80 years of age nowadays constitute a remarkable proportion of emergency department patients admitted by ambulance service. This group does not differ substantially from younger patients, neither in questions of inpatient or outpatient treatment nor in types of diagnosis. Elderly patients in the emergency department showed a higher mortality. Invasive interventions were less frequently used in this collective in comparison to younger patients. In consideration of the fact that the proportion of elderly will further increase in our population, this analysis may give basis for development of new strategies for the treatment of old patients in emergency departments.  相似文献   
76.
Gallbladder sludge and acute pancreatitis induced by acute hepatitis A.   总被引:1,自引:0,他引:1  
In this case report, a young woman with gallbladder sludge and acute pancreatitis due to acute hepatitis A (HAV) is presented. She was admitted to our hospital with abnormal hepatic enzymes. Five days prior to her admission, an initial abdominal ultrasound was performed at another hospital and revealed no abnormality, while her serum aspartate aminotransferase (AST) level was at the upper limit of normal (ULN) x 8. A second ultrasound was performed at our hospital and revealed a gallbladder wall thickness (9.3 mm), gallbladder sludge in the gallbladder lumen, pancreatic edema, ascites, and hepatomegaly while AST was at the ULN x 50. Magnetic resonance imaging and magnetic resonance cholangiopancreatography revealed imaging features of an acute stage of pancreatitis and gallbladder wall thickness with coexisting sludge in the gallbladder lumen. HAV infection was diagnosed by the detection of immunoglobulin M against HAV in the serum. The patient underwent two repeated abdominal ultrasound examinations on the 5th (AST was at the ULN x 3) and the 20th days (AST was at the normal) after her discharge, and both revealed normal findings. In our case, we observed reversible changes in the hepatobiliary and pancreatic system which was related to the severity of hepatic necro-inflammation. HAV-associated pancreatitis may be due to the formation of biliary sludge during the acute phase of the viral illness, but this association needs further investigation.  相似文献   
77.
78.
Using pupillometry and sympathetic skin responses we compared the changes in local and systemic autonomic function within one week of a migraine attack. We investigated whether the measurement of the pupillary light reflex provides further information on the pathophysiology of migraine. Forty-two migraine patients and forty-two healthy age-matched controls were included. The parameters that were measured were the amplitude of the pupillary light reflex, the pupil size at the beginning of the measurement, the latency, the velocity of constriction and the velocity at the end of the dilatation. The average pupil size was 6.43 mm in the migraine group and 6.7 mm in the control group (p < 0.01). Reduced velocity of constriction and smaller amplitude of constriction in migraine patients within two days of an attack were signs of a parasympathetic dysfunction (p < 0.05). The sympathetic skin response did not differ significantly between migraine sufferers and controls. These findings indicate that both parasympathetic and sympathetic nerves supplying the eye are involved in migraine headache presumably due to effects on the pericarotid sympathetic fibers and involvement of trigeminal-parasympathetic reflexes. Received: 24 July 2001, Accepted: 16 July 2002 Correspondence to K. Schepelmann, M. D.  相似文献   
79.
    
Ohne Zusammenfassung  相似文献   
80.
OBJECTIVE: Although somatoform disorders are assumed to be chronic clinical conditions, epidemiological knowledge on their natural course based on representative samples is not available. METHOD: Data come from a prospective epidemiologic study of adolescents and young adults in Munich, Germany. Respondents' diagnoses (N = 2548) at baseline and follow-up on average 42 months later are considered. The follow-up incidence, stability as well as selected baseline risk factors (sociodemographics, psychopathology, trauma exposure) for the incidence and stability of somatoform disorders and syndromes are prospectively examined. Diagnostic information was assessed by using the standardized Munich-Composite International Diagnostic Interview (M-CIDI). RESULTS: Over the follow-up period, incidence rate for any of the covered somatoform diagnoses was 25.7%. Stability for the overall group of any somatoform disorder/syndrome was 48%. Female gender, lower social class, the experience of any substance use, anxiety and affective disorder as well as the experience of traumatic sexual and physical threat events predicted new onsets of somatoform conditions, while stability was predicted by being female, prior existing substance use, affective and eating disorders as well as the experience of a serious accident. CONCLUSIONS: At least for a substantial proportion of individuals, the overall picture of somatization seems to be relatively stable, but with fluctuation in the symptom picture over time. Being female, the experience of substance use as well as anxiety disorder seem to constitute risk factors for the onset of new somatoform conditions as well as for a stable course over time.  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