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   55182篇
  免费   4313篇
  国内免费   145篇
耳鼻咽喉   672篇
儿科学   1450篇
妇产科学   708篇
基础医学   7142篇
口腔科学   808篇
临床医学   5843篇
内科学   10932篇
皮肤病学   698篇
神经病学   5206篇
特种医学   2147篇
外科学   10052篇
综合类   584篇
现状与发展   1篇
一般理论   60篇
预防医学   4713篇
眼科学   994篇
药学   3453篇
中国医学   48篇
肿瘤学   4129篇
  2023年   507篇
  2022年   904篇
  2021年   2179篇
  2020年   1147篇
  2019年   1826篇
  2018年   2203篇
  2017年   1563篇
  2016年   1594篇
  2015年   1763篇
  2014年   2511篇
  2013年   3102篇
  2012年   4769篇
  2011年   4687篇
  2010年   2486篇
  2009年   2121篇
  2008年   3346篇
  2007年   3526篇
  2006年   2996篇
  2005年   2709篇
  2004年   2424篇
  2003年   2065篇
  2002年   1837篇
  2001年   457篇
  2000年   458篇
  1999年   453篇
  1998年   374篇
  1997年   317篇
  1996年   236篇
  1995年   218篇
  1994年   179篇
  1993年   172篇
  1992年   330篇
  1991年   290篇
  1990年   248篇
  1989年   260篇
  1988年   202篇
  1987年   236篇
  1986年   217篇
  1985年   247篇
  1984年   169篇
  1983年   164篇
  1982年   137篇
  1981年   113篇
  1980年   118篇
  1979年   148篇
  1978年   106篇
  1976年   106篇
  1974年   106篇
  1973年   110篇
  1972年   106篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Desmoplastic malignant melanoma (DMM) is a rare variant of spindle cell melanoma. We report a case of DMM of the forehead secondarily involving the orbit. The diagnosis was based on light microscopic features, including prominent peripheral cell nest formation and spindle cell fascicles in densely collagenous stroma. Immunohistochemical studies showed strong uniform staining for S100 antigen throughout the tumour. It was negative for HMB 45, smooth muscle actin, desmin, cytokeratins and Type IV collagen. Electron microscopy showed neither melanosomes nor myelin figures. The clinical and histological characteristics of desmoplastic malignant melanoma, and its differential diagnosis of malignant schwannoma, are discussed. DMM has a poor prognosis, since it tends to invade deeply, recur locally and metastasise readily.  相似文献   
42.
Occupational stress in nursing has been a popular topic for investigation. In particular, comparisons between practice areas such as the intensive care unit (ICU) and medical-surgical unit have attempted to identify what factors are stressful, and whether some nursing environments are more stressful than others. Such studies have led to inconclusive findings. While many practice areas have been studied, the neurosurgical ICU and neuromedical/neurosurgical units have largely been overlooked. Using interviews, this exploratory study examined aspects of nursing perceived as stressful by staff members working in ICU and medical-surgical units in a neuroscience center. Findings suggested that patient care, communication, workload, management and supervision, organizational and personal circumstances are major sources of stress. These findings are in keeping with studies of stress conducted in national and international non-neurosurgical nursing practice areas.  相似文献   
43.
44.
Diagnosis and management of anaphylaxis   总被引:7,自引:0,他引:7       下载免费PDF全文
ANAPHYLAXIS IS A SEVERE SYSTEMIC ALLERGIC reaction that is potentially fatal. It requires prompt recognition and immediate management. Anaphylaxis has a rapid onset with multiple organ–system involvement and is mostly caused by specific antigens in sensitized individuals. Reactions typically follow a uniphasic course, however, 20% will be biphasic in nature. The second phase usually occurs after an asymptomatic period of 1–8 hours, but there may be a 24-hour delay. Protracted anaphylaxis may persist beyond 24 hours. Concurrent β-blocker therapy may adversely affect the response to management. Epinephrine is the treatment of choice and should be administered immediately. Secondary measures include circulatory support, H1 and H2 antagonists, corticosteroids and, occasionally, bronchodilators. Post-treatment observation of these patients is necessary, and they should remain within ready access of emergency care for the following 48 hours.  相似文献   
45.
We report a re-do case of severe aortic valve stenosis due to pannus formation 29 years after an aortic Starr-Edwards caged-ball valve implantation. A huge shelf of calcified and thick pannus tissue below the valve had reduced the already small orifice by at least a third in surface area. The explanted Starr-Edwards valve revealed no mechanical or structural failure. Early detection and treatment of pannus outgrowth is essential in order to prevent life-threatening prosthetic valve malfunctions.  相似文献   
46.
47.
Cardiovascular disease (CVD), which includes myocardial infarction(MI), stroke, and peripheral vascular disease, remains the leading cause of death in the United States and in most developed countries. In the United States today, 25% of patients have metabolic syndrome-including those who have had a prior occlusive vascular disease event, those who are having an acute MI or ischemic stroke, and finally, the largest segment of the population,namely those who have not yet experienced a clinical CVD, but whose risks are substantial (10-year risk 10%). This article reviews the totality of evidence for aspirin in the treatment and prevention of CVD and emphasizes its importance as adjunctive therapy for patients with metabolic syndrome.  相似文献   
48.
Unfractionated wheat gliadin was used to produce murine monoclonal antibodies to gliadin. A dot immunobinding assay, using these antibodies, was developed to detect possible gliadin contamination of nominally gluten-free flour, using dilute ethanol extracts spotted onto nitrocellulose membranes. The sensitivity of the assay was less than 10 micrograms/ml of unfractionated gliadin which permitted the detection of trace amounts of gliadin present in certain wheat starch based 'gluten-free' products. The assay detected not only wheat gliadin, but also prolamine extracts of rye, barley and oats; maize, soya and potato extracts as well as the control proteins casein and ovalbumin, gave negative results. The assay is of value as a simple and rapid method of screening foods for their suitability for consumption by patients with coeliac disease.  相似文献   
49.
1. The effects of capsaicin, calcitonin gene-related peptide and substance P were studied via three parameters in the guinea-pig vas deferens: the overflow of ATP and of tritiated noradrenaline, the mechanical responses to field stimulation and the mechanical responses to exogenous noradrenaline and alpha, beta-methylene ATP. 2. At 2 Hz, capsaicin inhibited the stimulus-evoked release of ATP, whereas it was without effect on the release of noradrenaline. At 20 Hz capsaicin did not affect the release of either of the cotransmitters. Capsaicin enhanced responses to alpha, beta-methylene ATP, but not to exogenous noradrenaline. 3. Calcitonin gene-related peptide, like capsaicin, inhibited the release of ATP, but not noradrenaline at 2 Hz and was without effect on release at 20 Hz. However, calcitonin gene related peptide inhibited responses to alpha, beta-methylene ATP and was without effect on responses to exogenous noradrenaline. 4. Substance P had no effect on the release of either noradrenaline or ATP at either frequency. However, like capsaicin it enhanced responses to alpha, beta-methylene ATP and was without effect on exogenous noradrenaline. 5. These results suggest that the actions of capsaicin on the guinea-pig isolated vas deferens are mediated via the release of both calcitonin gene-related peptide and substance P. Furthermore, as capsaicin and calcitonin gene-related peptide prejunctionally modulate purinergic, but not noradrenergic transmission, this suggests that the mechanisms for the storage and release of the sympathetic co-transmitters noradrenaline and ATP may not be the same.  相似文献   
50.
Reductions in serum levels of Gc globulin, a hepatically synthesized component of the extracellular actin scavenger system responsible for complexing circulating actin and attenuating intravascular microthrombus formation, are associated with poor outcome in acute liver failure. Clinically applicable assays of the important actin-free fraction (Af-Gc) have not been available until now. We measured actin-free Gc globulin levels with a novel, rapid assay in 61 cases of acute liver failure (ALF) and in 91 patients with cirrhosis (40 of whom were clinically unstable with extrahepatic organ dysfunction), and studied associations with liver dysfunction, extrahepatic organ dysfunction, indices of disseminated coagulation, and outcome. Reductions in Af-Gc levels mirrored hepatic dysfunction and organ dysfunction in both groups, and discriminated patients with poor prognosis from those with good prognosis in the ALF cohort. Levels were lowest in patients with ALF (10% of control values), but levels were also markedly reduced in both unstable (28%) and stable (44%) patients with cirrhosis. Associations with markers of disseminated intravascular coagulation were seen in both groups, most notably in the cirrhosis cohort, supporting a pathophysiological role for reduced Af-Gc in the evolution of organ dysfunction. In acetaminophen-induced ALF, Af-Gc identified patients with poor prognosis as well as did the Acute Physiology and Chronic Health Evaluation (APACHE II) score (area under the receiver operating characteristic curve, 0.7), and in cirrhosis, Af-Gc was an independent predictor of mortality by multifactorial analysis. In conclusion, the importance of Af-Gc reductions in the development of multiple organ dysfunction in ALF and cirrhosis is highlighted, probably resulting from reduced hepatic production and peripheral exhaustion of this arm of the extracellular actin scavenger system.  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