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   2391507篇
  免费   183040篇
  国内免费   4597篇
耳鼻咽喉   31757篇
儿科学   78852篇
妇产科学   68030篇
基础医学   348071篇
口腔科学   66120篇
临床医学   220344篇
内科学   468779篇
皮肤病学   53611篇
神经病学   194967篇
特种医学   89748篇
外国民族医学   702篇
外科学   347647篇
综合类   53659篇
现状与发展   4篇
一般理论   975篇
预防医学   193882篇
眼科学   54471篇
药学   171683篇
  8篇
中国医学   4907篇
肿瘤学   130927篇
  2019年   19197篇
  2018年   26496篇
  2017年   20247篇
  2016年   22592篇
  2015年   25529篇
  2014年   35943篇
  2013年   54291篇
  2012年   73596篇
  2011年   78490篇
  2010年   45953篇
  2009年   44007篇
  2008年   73192篇
  2007年   77987篇
  2006年   78014篇
  2005年   75955篇
  2004年   72921篇
  2003年   69647篇
  2002年   67443篇
  2001年   111887篇
  2000年   114241篇
  1999年   95386篇
  1998年   27160篇
  1997年   24642篇
  1996年   24969篇
  1995年   23688篇
  1994年   21772篇
  1993年   20365篇
  1992年   73847篇
  1991年   71709篇
  1990年   69075篇
  1989年   66536篇
  1988年   61338篇
  1987年   59973篇
  1986年   56565篇
  1985年   53754篇
  1984年   41012篇
  1983年   35279篇
  1982年   21192篇
  1981年   19185篇
  1979年   37636篇
  1978年   27190篇
  1977年   22656篇
  1976年   21212篇
  1975年   22322篇
  1974年   27123篇
  1973年   26456篇
  1972年   24948篇
  1971年   22983篇
  1970年   21723篇
  1969年   20364篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Liver disease alters the pharmacokinetic and pharmacodynamic properties of hepatically eliminated drugs. The main factors influenced are plasma albumin levels, enzyme balance (induction & inhibition) and drug binding to tissue proteins. The influence of lidocaine on serum, heart and liver propranolol levels in Wistar rats after liver injury induced by carbon tetrachloride CCl4 0.4 ml/kg x 2/wkl, was investigated. 40 male Wistar rats were divided into four groups (I, II, III, IV; n=10), Group I animals received only propranolol (labelled + cold substance) 40 mg/kg/12 h p.o., group II propranolol plus lidocaine in a single dose of 4mg/kg s.c., group III was treated with CCl4 for 6 weeks and received propranolol x2 at the same dosage as group I, while group VI was treated with CCl4 and the same drug dosage as group II. The simultaneous administration of H3-propranolol and lidocaine increased propranolol levels in the serum and tissues. The liver in damaged animals showed an increase of propranolol level under lidocaine co-administration, probably due to CCl4 induced liver enzyme activity, resulting in a rapid propranolol metabolism or to competition between both drug protein binding sites. The increased propranolol levels in the heart after lidocaine administration were probably due to attributed to its high affinity for heart tissue. Consequently, as regards the therapeutic approach for patients with liver disease receiving propranolol their propranolol dosage should be reduced when lidocaine is co-administered.  相似文献   
22.
There is a great deal of interest in developing less invasive markers for monitoring airway inflammation and the effect of possible novel anti-inflammatory therapies that may take time to impact on disease pathology. Exhaled nitric oxide (eNO) has been shown to be a reproducible, noninvasive indicator of the inflammatory status of the airway in the clinic. The aim of the present study was to determine the usefulness of measuring eNO as a marker of the anti-inflammatory impact of glucocorticoid and an inhibitor of kappaB kinase-2 (IKK-2) inhibitor 2-[(aminocarbonyl)amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide (TPCA-1), in a pre-clinical model of airway inflammation. Rats were given vehicle, budesonide or TPCA-1 prior to exposure to lipopolysaccharide, previously shown to induce an increase in eNO and airway neutrophilia/eosinophilia. Comparison of the effect of the two compounds on inflammatory components demonstrated a significant correlation between the impact on eNO and inflammatory cell burden in the airway. The current study demonstrates the usefulness of profiling potential disease-modifying therapies on exhaled nitric oxide levels and the way in which an effect on this noninvasive biomarker relates to effects on pathological parameters such as lung cellularity. Information from studies such as the current one would suggest that the measurement of exhaled nitric oxide has potential for monitoring inflammatory status in lung tissue.  相似文献   
23.
The overnight one-mg dexamethasone suppression test has been used for many years to screen for Cushing's syndrome. This test has usually been evaluated in controls versus patients with severe hypercortisolism. Under these conditions, the overnight dexamethasone suppression test has been reported to have high sensitivity and specificity. The objective of this study was to determine the sensitivity of the one mg overnight dexamethasone suppression test in patients with mild and/or periodic Cushing's syndrome. Therefore, an overnight dexamethasone suppression test was performed in 17 consecutive patients presenting to an endocrinology clinic with signs and symptoms of hypercortisolemia who were later proven to have Cushing's syndrome. The majority of patients were found to have both mild and periodic hypercortisolism. One mg of dexamethasone was given at midnight and a plasma cortisol was measured by radioimmunoassay at 08:00 the following morning. Using a cut-off for a morning cortisol following overnight dexamethasone of > 5 microg/dL, only three of 17 patients failed to suppress to a value less than this cut-off (sensitivity 18 %). A cut-off of > 2 microg/dL gave similar sensitivity. Even with a stringent cut-off point of > 1.8 microg/dL, only seven of 17 patients failed to suppress to a value less than this cut-off point (sensitivity of 41 %). These results demonstrate that the great majority of patients with mild and/or periodic Cushing's syndrome suppress to overnight dexamethasone. Since patients with mild and/or periodic Cushing's syndrome are the patients in whom the identification of hypercortisolism is difficult, our results from this relatively small study suggest that this test should no longer be used to exclude these patients from further workup for Cushing's syndrome.  相似文献   
24.
The present study compared four different sites and conditions for the measurement of maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in 38 spontaneous breathing tracheotomised patients. Of the patients, 28 had chronic obstructive pulmonary disease (COPD). The four different conditions were: 1) through a cuff inflated cannula (condition A); 2) through the mouth with a deflated cannula (condition B); 3) through the mouth with a phonetic uncuffed cannula (condition C); and 4) through the mouth after stoma closure (condition D). Five trials in each condition were performed using a standardised method. The measurement of both MIP and MEP differed significantly depending on the condition of measurement. MIP taken in condition A was significantly higher when compared with conditions B, C and D. MEP in condition A was significantly higher when compared with condition B and D. In condition A the highest frequency of the best measurement of MIP and MEP was observed at the fourth and fifth effort, respectively. The same results were obtained after the selection of only COPD patients. In conclusion, respiratory muscle assessment differs significantly depending on measurement condition. Measurement through inflated cannula tracheotomy yields higher values of both maximal inspiratory and maximal expiratory pressure.  相似文献   
25.
26.
Summary: A female patient with isovaleric acidaemia had a successful outcome from pregnancy.  相似文献   
27.
28.
29.
30.
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.  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