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   4737篇
  免费   259篇
  国内免费   201篇
耳鼻咽喉   35篇
儿科学   59篇
妇产科学   36篇
基础医学   497篇
口腔科学   167篇
临床医学   272篇
内科学   339篇
皮肤病学   195篇
神经病学   349篇
特种医学   93篇
外科学   259篇
综合类   621篇
现状与发展   2篇
预防医学   396篇
眼科学   77篇
药学   1512篇
  2篇
中国医学   210篇
肿瘤学   76篇
  2023年   25篇
  2022年   39篇
  2021年   133篇
  2020年   84篇
  2019年   92篇
  2018年   73篇
  2017年   97篇
  2016年   132篇
  2015年   134篇
  2014年   227篇
  2013年   295篇
  2012年   245篇
  2011年   311篇
  2010年   211篇
  2009年   205篇
  2008年   236篇
  2007年   245篇
  2006年   206篇
  2005年   192篇
  2004年   184篇
  2003年   159篇
  2002年   124篇
  2001年   95篇
  2000年   91篇
  1999年   90篇
  1998年   76篇
  1997年   89篇
  1996年   81篇
  1995年   83篇
  1994年   90篇
  1993年   80篇
  1992年   52篇
  1991年   54篇
  1990年   73篇
  1989年   66篇
  1988年   50篇
  1987年   39篇
  1986年   38篇
  1985年   62篇
  1984年   51篇
  1983年   41篇
  1982年   38篇
  1981年   48篇
  1980年   35篇
  1979年   20篇
  1978年   27篇
  1977年   17篇
  1976年   25篇
  1975年   12篇
  1974年   11篇
排序方式: 共有5197条查询结果,搜索用时 15 毫秒
81.
Abstract

We present a case of ingestion of a commonly used stool fixative containing 675?mg of mercuric chloride per 15 mL vial. Early chelator therapy with dimercaprol and aggressive hydration were initiated and the patient remained asymptomatic. Safety packaging of this product is recommended.  相似文献   
82.
Lubiprostone, a locally acting highly selective type-2 chloride channel activator, has been US FDA approved since January 2006 for the treatment of adults with chronic idiopathic constipation and FDA approved since April 2008 for the treatment of woman aged 18 years or older suffering from irritable bowel syndrome (IBS) with constipation. Through activation of the type-2 chloride channels located on the luminal side of intestinal epithelial cells, it promotes fluid secretion, increasing the liquid content of stool and accelerating small bowel as well as colonic transit. Lubiprostone has demonstrated efficacy with respect to increasing weekly spontaneous bowel movements and improving stool consistency, straining and constipation severity, both in short- and long-term studies. It has also demonstrated efficacy in the treatment of IBS with constipation, with beneficial effects on global symptoms, abdominal pain, constipation-related symptoms and overall quality of life. There is no evidence of a rebound in constipation or IBS symptoms following cessation of lubiprostone. In general, lubiprostone is well tolerated, with the most common side effects including nausea, headache and diarrhea.  相似文献   
83.
Secretory diarrhea is a leading cause of morbidity and mortality worldwide. Crofelemer is a first-in-class antidiarrheal agent that simultaneously targets two distinct channels, the cystic fibrosis conductance regulator and calcium-activated chloride channel, responsible for chloride and fluid secretion in the GI tract. Crofelemer is a novel compound extracted from the stem bark latex of the Croton lechleri tree found in the western Amazonian region of South America. There is little to no systemic absorption of crofelemer when given orally and studies have shown minimal toxicity beyond mild gastrointestinal effects. In studies in diarrheal illness associated with primarily a secretory component, such as cholera, travelers’ diarrhea and acute infectious diarrhea, crofelemer has shown improvements in stool consistency and duration of symptoms. Less clear, but interesting, results have been observed in other diarrheal diseases associated with a mixed pathology, including diarrhea in patients with HIV and diarrhea-predominant irritable bowel syndrome.  相似文献   
84.
Context: Ethyl chloride (EC) is a fast-acting vapo-coolant spray that provides rapid, transient, local analgesia for minor invasive procedures. Although the application of EC has decreased, it can be used as a cryoanalgesic agent in minor surgical procedures. Objective: Despite the widespread use of EC as a local anesthetic, there are few reported cases of serious adverse side effects. Material and methods: We report a 67-year old otherwise healthy man who underwent excision of a papilloma on his superior right eyelid by a general practitioner at a primary care center. The lesion was removed by curettage after slight freezing with EC spray. This chemical agent was applied without the adequate eye protection, and eight hours later the patient presented an acute frost injury of ocular surface. Results: Urgent treatment included copious irrigation of the affected eye, especially the conjunctival fornices, corticosteroid (prednisone) and antibiotic (neomycin) ointment. A week later, the eyelid lesion and keratoconjunctivitis had resolved but evidence of early cicatrization involving the inferior conjucntival fornix and symblepharon formation were present. Discussion: To the best of our knowledge, this is the first reported case of an acute burn of the ocular surface following EC spray exposure. Conclusion: EC should be avoided for short-term local anesthesia in the periocular region to prevent this serious complication.  相似文献   
85.
Di-isononyl phthalate (DINP) is a high molecular weight general purpose plasticizer used principally in the manufacture of flexible polyvinyl chloride (PVC) articles. DINP metabolites can be measured in biological media such as blood and urine. However, measurement of a substance in the blood or urine does not by itself mean that the chemical causes or is associated with adverse health outcomes. This is particularly pertinent given the advances in modern analytical techniques whereby ever diminishing trace amounts of substances can be detected. Therefore, it is a scientific necessity that risk assessors understand the relationship of biomonitoring data to estimation of exposure so that appropriate comparisons can be made to the no observed adverse effects levels (NOAELs) or other points of departure from toxicological studies in animals. In this paper, estimates of daily DINP intake are calculated for various population segments based on urinary biomonitoring data and are compared to estimates of exposure based on indirect methods and to health-based exposure guidance values. In general, intake estimates converge on a mean of 1–2 μg/kg/day regardless of source of exposure or population cluster; a value 2-orders of magnitude lower than health-based exposure guidance values, ranging from 120 to 290 μg/kg/day, which have been established by regulatory authorities and other authoritative bodies as representing acceptable levels.  相似文献   
86.
Probiotic organisms have shown promise in treating diseases. Previously, we have reported on the efficacy of microencapsulated Lactobacillus reuteri NCIMB 30242 in a yogurt formulation at lowering serum cholesterol levels in otherwise healthy hypercholesterolemic adults. This study investigates the safety and toxicology of oral ingestion of microencapsulated L. reuteri NCIMB 30242 in a yogurt formulation. A randomized group of 120 subjects received a dose of 5 × 1010 CFU microencapsulated L. reuteri NCIMB 30242 in yogurt (= 59) or placebo yogurt (= 61) twice/day for 6 weeks. Clinical chemistry and hematological parameters of safety were analyzed. Fecal samples were collected at these time points for the analysis of deconjugated bile acids. The frequency, duration and intensity of adverse events (AEs) and clinical significance of safety parameters were recorded for both groups. No clinically significant differences between the probiotic yogurt and placebo yogurt treated groups were detected in either the blood clinical chemistry or hematology results and there was no significant increase in fecal deconjugated bile acids (> 0.05) between treated and control groups. The frequency and intensity of AEs was similar in the two groups. These results demonstrate the safe use of this formulation in food.  相似文献   
87.
Adrenal epithelioidangiosarcoma (AEA) is a rare neoplasm that accounts for less than 1% of sarcomas. Due to its rarity, it can easily be misdiagnosed, both by the clinician and the pathologist. Data on the patient’s occupational history was collected and analyzed. The bibliographic data was found on the PUBMED bibliographic search site after entering the word “extrahepaticangiosarcoma”. We report a case of adrenal epithelioidangiosarcoma (AEA) in a 68 yr-old Caucasian male factory worker exposed to Vinyl Chloride (VC) for 15 yr. He underwent surgery, chemotherapy and radiotherapy. Hepatic angiosarcoma is a known consequence of VC exposure, but occupational causality of extra-hepatic angiosarcoma is controversial. Extra-hepatic angiosarcomas have been reported in VC workers, but never AEA. Cancerogenic effects of VC involve all endothelial areas of the body and extra-hepatic endothelial tumors may also be caused by this substance. This is the first published report of AEA diagnosed in a worker exposed to VC.  相似文献   
88.
Sweating is an important physiological process to regulate body temperature in humans, and various disorders are associated with dysregulated sweat formation. Primary sweat secretion in human eccrine sweat glands involves Ca2+‐activated Cl? channels (CaCC). Recently, members of the TMEM16 family were identified as CaCCs in various secretory epithelia; however, their molecular identity in sweat glands remained elusive. Here, we investigated the function of TMEM16A in sweat glands. Gene expression analysis revealed that TMEM16A is expressed in human NCL‐SG3 sweat gland cells as well as in isolated human eccrine sweat gland biopsy samples. Sweat gland cells express several previously described TMEM16A splice variants, as well as one novel splice variant, TMEM16A(acΔe3) lacking the TMEM16A‐dimerization domain. Chloride flux assays using halide‐sensitive YFP revealed that TMEM16A is functionally involved in Ca2+‐dependent Cl? secretion in NCL‐SG3 cells. Recombinant expression in NCL‐SG3 cells showed that TMEM16A(acΔe3) is forming a functional CaCC, with basal and Ca2+‐activated Cl? permeability distinct from canonical TMEM16A(ac). Our results suggest that various TMEM16A isoforms contribute to sweat gland‐specific Cl? secretion providing opportunities to develop sweat gland‐specific therapeutics for treatment of sweating disorders.  相似文献   
89.
Benzalkonium chloride (BAC) is a widely used disinfectant/preservative, and respiratory exposure to this compound has been reported to be highly toxic. Spray‐form household products have been known to contain BAC together with triethylene glycol (TEG) in their solutions. The purpose of this study was to estimate the toxicity of BAC and TEG mixtures to pulmonary organs using in vitro and in vivo experiments. Human alveolar epithelial (A549) cells incubated with BAC (1‐10 μg/mL) for 24 hours showed significant cytotoxicity, while TEG (up to 1000 μg/mL) did not affect cell viability. However, TEG in combination with BAC aggravated cell damage and inhibited colony formation as compared to BAC alone. TEG also exacerbated BAC‐promoted production of reactive oxygen species (ROS) and reduction of glutathione (GSH) level in A549 cells. However, pretreatment of the cells with N‐acetylcysteine (NAC) alleviated the cytotoxicity, indicating oxidative stress could be a mechanism of the toxicity. Quantification of intracellular BAC by LC/MS/MS showed that cellular distribution/absorption of BAC was enhanced in A549 cells when it was exposed together with TEG. Intratracheal instillation of BAC (400 μg/kg) in rats was toxic to the pulmonary tissues while that of TEG (up to 1000 μg/kg) did not show any harmful effect. A combination of nontoxic doses of BAC (200 μg/kg) and TEG (1000 μg/kg) promoted significant lung injury in rats, as shown by increased protein content and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage fluids (BALF). Moreover, BAC/TEG mixture recruited inflammatory cells, polymorphonuclear leukocytes (PMNs), in terminal bronchioles and elevated cytokine levels, tumor necrosis factor α (TNF‐α), and interleukin 6 (IL‐6) in BALF. These results suggest that TEG can potentiate BAC‐induced pulmonary toxicity and inflammation, and thus respiratory exposure to the air mist from spray‐form products containing this chemical combination is potentially harmful to humans.  相似文献   
90.
BACKGROUND AND AIMS: Conflicting results exist with regard to metabolic acid-base status in liver cirrhosis, when the classic concept of acid-base analysis is applied. The influence of the common disturbances of water, electrolytes and albumin on acid-base status in cirrhosis has not been studied. The aim of this study was to clarify acid-base status in cirrhotic patients by analyzing all parameters with possible impact on acid-base equilibrium. PATIENTS AND METHODS: Fifty stable cirrhotic patients admitted to a university hospital. Arterial acid-base status was analyzed using the principles of physical chemistry and compared with 10 healthy controls. RESULTS: Apart from mild hypoalbuminemic alkalosis, acid-base state was normal in Child-Pugh A cirrhosis. Respiratory alkalosis was the net acid-base disorder in Child-Pugh B and C cirrhosis with a normal overall metabolic acid-base state (Base excess-1.0 (-3.6 to 1.6) vs 1.1 (-0.2 to 1.1) mmol/l, P = 0.136, compared with healthy controls, median (interquartile range)). Absence of an apparent metabolic acid-base disorder was based on an equilibrium of hypoalbuminemic alkalosis and of dilutional acidosis and hyperchloremic acidosis. CONCLUSION: A balance of offsetting acidifying and alkalinizing metabolic acid-base disorders leaves the net metabolic acid-base status unchanged in cirrhosis.  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