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   16236篇
  免费   854篇
  国内免费   65篇
耳鼻咽喉   164篇
儿科学   498篇
妇产科学   311篇
基础医学   2132篇
口腔科学   276篇
临床医学   1312篇
内科学   4064篇
皮肤病学   223篇
神经病学   1888篇
特种医学   774篇
外科学   1981篇
综合类   38篇
一般理论   3篇
预防医学   730篇
眼科学   146篇
药学   1104篇
中国医学   31篇
肿瘤学   1480篇
  2023年   75篇
  2022年   156篇
  2021年   335篇
  2020年   208篇
  2019年   291篇
  2018年   347篇
  2017年   266篇
  2016年   329篇
  2015年   329篇
  2014年   510篇
  2013年   650篇
  2012年   940篇
  2011年   1005篇
  2010年   564篇
  2009年   513篇
  2008年   873篇
  2007年   902篇
  2006年   821篇
  2005年   803篇
  2004年   746篇
  2003年   689篇
  2002年   672篇
  2001年   423篇
  2000年   429篇
  1999年   448篇
  1998年   198篇
  1997年   133篇
  1996年   124篇
  1995年   117篇
  1994年   104篇
  1993年   96篇
  1992年   288篇
  1991年   267篇
  1990年   281篇
  1989年   261篇
  1988年   195篇
  1987年   173篇
  1986年   191篇
  1985年   218篇
  1984年   132篇
  1983年   104篇
  1982年   82篇
  1981年   52篇
  1980年   50篇
  1979年   112篇
  1977年   58篇
  1976年   56篇
  1975年   53篇
  1974年   55篇
  1973年   60篇
排序方式: 共有10000条查询结果,搜索用时 178 毫秒
21.
Objects Genetic syndromes associated with ependymoma are uncommon, with the exception of NF2. We describe two cases of ependymoma presenting with Klinefelter’s Syndrome (KS) as co-morbid condition. Materials and methods The first patient was diagnosed for KS during pregnancy; he also presented a thyroid agenesis and a deficit of methyltetrahydrofolate reductase (MTHFR); at 30 months of age he was operated on for a grade II ependymoma of IV ventricle; after a multiple-stage surgery, he underwent oral chemotherapy and stereotactic radiotherapy, but after 15 months he presented a local recurrence and died. The second patient was diagnosed for KS at the age of 16 months; at 10 years of age, due to back pain, he underwent an MRI, which showed a cauda equine tumor. He underwent surgery and radiotherapy. Histology was of mixopapillary ependymoma. Conclusion In a review of literature, various neoplasms have been described in association with KS. To our knowledge, these are the first two cases reported of ependymoma associated to KS. A retrospective study of 44 monoinstitutional ependymoma cases demonstrated association with genetic syndromes in 22%.  相似文献   
22.
23.
Results of a recent study have demonstrated that exposure to multiple ethanol concentrations and repeated ethanol deprivation periods in Indiana ethanol-preferring (P) rats resulted in the development of an alcohol deprivation effect (ADE; the temporary increase in voluntary ethanol intake after a period of deprivation from ethanol) characterized by consumption of intoxicating amounts of ethanol. The current study was designed to possibly extend these results to Sardinian alcohol-preferring (sP) rats, generated with the same selective program previously used for P rats. To this aim, ethanol-naive sP rats were exposed initially to the home cage four-bottle choice [10%, 20%, and 30% (vol./vol.) ethanol solutions and water] for eight consecutive weeks. Subsequently, rats were divided into two groups: The first group had continuous access to the four-bottle regimen (nondeprived rats), and the second group was exposed to five cycles of 14-day periods of deprivation from ethanol and 14-day periods of reexposure to the four-bottle regimen. An ADE developed after each deprivation period. However, the extra intake of ethanol was limited to the first hour of each reaccess period. Magnitude of ADE did not change with repeated periods of deprivation. However, a shift in preference toward the two highest concentrations of ethanol solutions was evident from the first reexposure to ethanol and was maintained throughout the study. These results provide further evidence on the heterogeneity of ethanol-drinking behavior among rat lines selectively bred for high ethanol preference and consumption.  相似文献   
24.
Background: Bowel obstruction is a common and distressing outcomein patients with abdominal or pelvic cancer. Patients and methods: Patients may develop bowel obstructionat any time in their clinical history, with an incidence rangingfrom 5.5% to 42% in ovarian carcinoma and from 10% to 28.4%in colorectal cancer. The causes of the obstruction may be benignpostoperative adhesions, a focal malignant or benign deposit,relapse or diffuse carcinomatosis. The symptoms which are almostalways present are intestinal colic (reported in 72%–76%of patients), abdominal pain due to distension, hepatomegalyor tumor masses (in 92% of patients) and vomiting (68%–100%)of cases. Conclusion: While surgery must remain the primary treatmentfor malignant obstruction, it is now recognised that there isa group of patients with advanced disease or poor general conditionwho are unfit for surgery and require alternative managementto relieve distressing symptoms. A number of treatment optionsare now available for the patient with advanced cancer who developsintestinal obstruction. In this review of the literature, theindications for surgery will be examined, the use of nasogastrictube and percutaneous gastrostomy evaluated and the place ofdrugs for symptom control described. bowel obstruction, advanced and terminal cancer patients  相似文献   
25.
Blood levels of acetaldehyde (ACh), ethanol and acetone were investigated in mice treated with ethanol for 6 months and receiving compatible erythrocytes (RBCs) overloaded with aldehyde dehydrogenase (AlDH). Following an acute dose of ethanol, ACh levels were significantly lower in these animals than in alcohol-treated mice receiving AlDH-unloaded RBCs, and were similar to the ACh levels of normal mice. The peak ethanol concentration was higher in normal mice than in both groups of alcohol-treated animals, while acetone concentrations were not significantly different in the three groups of animals.  相似文献   
26.
Several types of chronic pain syndromes are effectively treated with sodium channel blockers such as lignocaine. Further investigation of this therapeutic modality would be facilitated by refinement of the parameters describing lignocaine distribution and elimination. This would allow precise lignocaine infusion by a computer-controlled infusion to attain and maintain stable target lignocaine concentrations. Arterial blood samples were obtained at frequent intervals during a computer-controlled infusion of lignocaine in 12 adult human volunteers. Plasma lignocaine concentrations of 1, 2, 3, 4 and 5 microg/ml were targeted for 15 min at each concentration. A three-compartment mammillary pharmacokinetic model best described the resulting concentration vs time profile. A population pharmacokinetic analysis was performed using three different techniques; the two-stage, pooled and mixed effects modelling. There was marked overshoot of the plasma concentration above the target prior to refinement of the pharmacokinetic parameters. The best parameters of a three-compartment mammillary model fit to the measured concentration using the pooled data approach were: V(1) = 7.44, V(2) =11.5 and V(3) = 97.71; Cl(1) = 0.585, Cl(2) = 2.23 and Cl(3) =1.64 l/min. Similarly calculated parameters using NONMEM were V(1) = 6.99, V(2) =12.2 and V(3) =1341; Cl(1) = 0.703, Cl(2) =1.24 and Cl(3) =1.49 l/min. The addition of age as a covariate of the pharmacokinetic parameters improved the model in both cases. Height, lean body mass and body surface area as covariates of the pharmacokinetic parameters did not improve the predicted value of the model. Prospective testing of the pharmacokinetic parameters will be required to define whether they function well. The refinement of pharmacokinetic parameters for the computer-controlled intravenous infusion of lignocaine will facilitate further research in pain therapy. Published lignocaine pharmacokinetic values have a relatively large central volume of distribution, and hence, when implemented as a computer-controlled infusion, result in dramatic overshoot shortly after targeting a higher plasma concentration. In light of the long-lasting pain relief provided by sodium channel blockade in neuropathic pain states, overshoot of plasma concentrations must be avoided if the concentration vs effect relationship is to be defined.  相似文献   
27.
28.
29.
The objective of this study was to find the incidence of accidental exposures to blood and body fluids among surgeons during operations and to describe their dynamics. A probabilistic model was also used to predict the cumulative 30-year risk to the surgeon of contracting hepatitis B and C viruses (HBV, HCV) or human immunodeficiency virus (HIV) infection and estimate the effect of preventive strategies in reducing this risk. A multicentric prospective survey, based on self-administered questionnaires, was conducted during a period of 6 months in 39 Italian hospitals. An accidental exposure to blood or body fluids occurred in 9.2% of 15,375 operations. In about 2% of procedures a parenteral-type injury, such as actual skin puncture or eye contamination, was suffered by the operating surgeon. A needle-stick injury was the commonest accident, and its occurrence was found to vary with the phase of the procedure and its length. The current lifetime risk of acquiring HBV, HCV, and HIV infection in our regions was estimated to be as high as 42.7%, 34.8%, and 0.54%, respectively. The adoption of preventive strategies is expected to reduce this risk to 21% for HBV, 16.6% for HCV, and 0.23% for HIV infection. Active immunization of surgeons against HBV is strongly recommended. The case is also made for the use of a face-shield combined with a permanent change in our surgical practice capable of reducing the current high rate of parenteral injuries.  相似文献   
30.
Two unrelated children displayed attacks of paroxysmal jerky 'puppet-like' movements lasting 2-3 min. The attacks were not kinesigenic and occurred during wakefulness precipitated by physical exercise and during NREM sleep, spontaneous or upon arousal and awakenings. Paroxysmal dystonic choreoathetosis was excluded by the absent family history, and paroxysmal kinesigenic dystonia by the absence of triggering effects by sudden movements and efficacy of anticonvulsants. Pattern and duration of involuntary movements were not those typical of nocturnal paroxysmal dystonia. Our cases emphasize that overlap exists among the different clinical categories of paroxysmal dyskinesia.  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