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   7898篇
  免费   698篇
  国内免费   236篇
耳鼻咽喉   141篇
儿科学   147篇
妇产科学   97篇
基础医学   575篇
口腔科学   230篇
临床医学   1579篇
内科学   688篇
皮肤病学   124篇
神经病学   1377篇
特种医学   218篇
外科学   621篇
综合类   1052篇
一般理论   1篇
预防医学   873篇
眼科学   75篇
药学   460篇
  9篇
中国医学   428篇
肿瘤学   137篇
  2024年   38篇
  2023年   208篇
  2022年   359篇
  2021年   525篇
  2020年   464篇
  2019年   429篇
  2018年   434篇
  2017年   388篇
  2016年   328篇
  2015年   304篇
  2014年   580篇
  2013年   620篇
  2012年   492篇
  2011年   546篇
  2010年   354篇
  2009年   397篇
  2008年   351篇
  2007年   330篇
  2006年   233篇
  2005年   193篇
  2004年   175篇
  2003年   157篇
  2002年   117篇
  2001年   113篇
  2000年   82篇
  1999年   70篇
  1998年   60篇
  1997年   41篇
  1996年   53篇
  1995年   44篇
  1994年   43篇
  1993年   42篇
  1992年   28篇
  1991年   29篇
  1990年   27篇
  1989年   20篇
  1988年   25篇
  1987年   22篇
  1986年   13篇
  1985年   22篇
  1984年   15篇
  1983年   11篇
  1982年   6篇
  1981年   2篇
  1980年   5篇
  1979年   10篇
  1978年   6篇
  1977年   2篇
  1976年   5篇
  1975年   12篇
排序方式: 共有8832条查询结果,搜索用时 15 毫秒
11.
Self-assessment scales have long been used in psychiatric research even if their validity has often been questioned, one reason being poor the concordance of expert ratings. In clinical practice the use of rating scales is restricted, since they are considered to be time-consuming and perhaps even to disrupt the clinician's rapport with the patient. In the present study, a self-assessment scale, the CPRS Self-rating Scale for Affective Syndromes (CPRS-S-A), was constructed by re-phrasing in a self-rating format 19 items from the original Comprehensive Psychopathological Rating Scale (CPRS) and covering depression, anxiety and obsessional symptoms. In a group of 30 patients with depression syndromes and anxiety syndromes, the CPRS-S-A and the original CPRS were both used on 2 occasions. The patient's Global Assessment of Functioning scores ranged from 30 to 76 (mean 58), which suggests a moderate severity of illness, as does the fact that the majority were outpatients. There was a high degree of concordance between the instruments for most items and for the scores on the subscales for both diagnostic groups (i.e., the Montgomery-Åsberg Depression Rating Scale and the Brief Anxiety Scale, which are both subscales drawn from the CPRS). The time taken to complete the CPRS-S-A varied from 5 to 30 min (mean 19 min for depressive and 16 min for anxiety patients on the first occasion, 13 min for both groups on the second), and the self-rating procedure was readily accepted by both groups of patients. The CPRS-S-A would thus seem to be a promising instrument for quantitative rating of symptoms in ambulatory patients, both in clinical practice and in research.  相似文献   
12.
13.
Sequential salivary gland scintigraphy with 99mTc-technetium pertechnetate (Tc-99) is a safe, minimally invasive test for study of major salivary glands. However, its relationship to salivary function has not been investigated in detail. We have investigated the relationship between major salivary gland flow rates and Tc-99 scans and developed a new rating scale using scans of a control group with normal salivary function. Salivary flow rates and Tc-99 scans were obtained from healthy, non-medicated subjects (n = 33) and from xerostomic patients (n = 22). There were significant differences between the groups for salivary flow rates and Tc-99 ratings. Significant correlations were found between salivary flow rates and Tc-99 ratings in the control and xerostomic groups. The Tc-99 rating scale proved reliable in assessing salivary dysfunction, and showed a high inter-examiner correlation. These results demonstrate the usefulness of salivary gland scintigraphy in assessing major salivary gland flow rates and the utility of a new rating scale.  相似文献   
14.
Previous research has shown that separation discrimination thresholds are independent of the internal spatial scale (local spatial frequency) of the targets whose separation is being judged. The experiments reported here tested the generality of this conclusion for separation discrimination of targets that were embedded in an array of identical objects, where crowding could enhance the importance of the scale at which the individual target locations are encoded. No effect of the local spatial scale of the targets was found under these conditions.  相似文献   
15.
BACKGROUND: Seizure frequency is in abnormal distribution, and it is not enough to express the trend of concentration using means, and its median loses a lot of information, thus it lacks of a standard for evaluating the therapeutic effects based on seizure frequency. OBJECTIVE: To establish a method for evaluating the therapeutic effects on anti-epileptic drugs using changes of interval and duration of seizure. DESIGN: A prospective cohort study. SETTING: Zhumadian Psychiatric Hospital. PARTICIPANTS: Outpatients and inpatients suffering from epilepsy attending firstly visited Zhumadian Psychiatric Hospital from June 2001 to June 2002 were enrolled. They were diagnosed as epileptic according to the International Classification of Epileptic Seizure by International League Against Epilepsy (1981) based on the clinical history, physical examination, and investigations. The interval time was no more than 6 months. Informed consent was obtained from all the subjects, and the study was approved by the hospital ethical committee. METHODS: ① For the first visit and each follow-up, the following data were recorded, including general demographic information, seizure type, the date and time of ictus, the duration of ictus, and inducement or situation related, according to which the following indexes could be calculated, including seizure styles, interval, duration, cluster frequency and cluster duration. The information from the first review was noted as annals A. The second interview was taken at the end of the evaluating period; the information from the second review was noted as annals B. The third interview was taken within two weeks after the second one; the information from the third review was noted as annals C. The annals B or the annals C were respectively compared with the annals A in the light of the same types or the same styles of the same patient. Summation of the scores of interval change and duration change of the same type or the same style and 5 of basic score was the score of a corresponding seizure type or a corresponding style of one patient. In order to test its reliability and validity, the score of change of frequency or duration plus 5 scores respectively was the score of frequency or duration. ② Reliability and validity were tested by calculating corresponding correlation coefficient with SPSS 11.0. ROC curve was used for developing diagnostic criterion of predicting therapeutic effects with SPSS 11.0. MAIN OUTCOME MEASURES: ① Reliability and validity; ② Diagnostic criterion for predicting therapeutic effects one year later. RESULTS: Totally 28 patients were involved in the final analysis of results. ① Reliability and validity were high: rinter-rater=0.98, rtest-retest=0.99, rconstruct validity=0.83. ② A total score > 6 was the optimal diagnostic criteria for predicting therapeutic effects one year later, in other words, a patient who scored more than 6 at the evaluating period may be seizure-free one year later. CONCLUSION: It is a potential tool for evaluating epileptic therapeutic outcome, and it can be diffusely used in interrelated fields after being further validated.  相似文献   
16.
The Depression Scale (DEPS), a new screening instrument for detecting depression in primary health care, was compared with the Hamilton Depression Scale (HDS) among 50 suicide attempters. Using the HDS as a gold standard, the positive and negative predictive values of the DEPS for the diagnosis of depression were 98% and 20%, respectively. The correlation between the total HDS scores and the total DEPS scores was 0.60. The DEPS may help general practitioners to detect depression among suicide attempters, but it should not be used to exclude depression.  相似文献   
17.
People undergoing medical procedures sometimes experience feelings that may influence the results. In this study, we explore the relationship between changes in mood state self-ratings and cerebral glucose metabolism during positron emission tomography (PET) in persons with age-associated memory impairment (mean age 59.4±9.8 years). Brain regions of interest involved in both mood and memory were examined. Mood ratings of increased boredom correlated significantly with mesial temporal and parietal asymmetry and decreased parietal metabolism. Mood ratings of increased fatigue correlated with basal ganglia asymmetry and the right basal ganglia and left mesial temporal metabolism. These findings suggest that subjective mood state changes during PET may influence metabolism in brain regions implicated in emotion and memory function in people with age-related memory complaints.  相似文献   
18.
There is a great need today for clinically useful instruments in the rehabilitation of chronic pain patients. The Arthritis Self-efficacy Scale measures patients' perceived self-efficacy to cope with the consequences of chronic arthritis. The aim of the present study was to evaluate a Swedish version of the Arthritis Self-efficacy Scale with respect to factor structure and reliability. Twenty-five chronic pain patients and twenty-four rheumatology patients were given a Swedish version of the Arthritis Self-efficacy Scale twice within a three week interval. The three factor structure of the scale was confirmed; Cronbach's alpha for internal consistency ranged between 0.82-0.91 and test-retest correlations ranged between 0.81-0.91, showing that the instrument satisfactorily met psychometric standards.  相似文献   
19.
We have investigated the effect of growth and induction conditions on the production of soluble single-chain Fv antibody fragments in Escherichia coli under the control of wt lac promoter. The scFv was directed into the periplasmic space by a pelB leader sequence. Addition of sucrose to the medium gave a 15–25-fold increase in the yield of soluble scFv-phOx (3.0 mg/l) for bacterial shake-tube cultures and an increase of 80–150-fold (16.5 mg/l) for shake-flask cultures. Using flask culture in the presence of 0.4 M sucrose, a significant amount of scFv was released into the medium. We found that the scFv could be made to accumulate in the periplasm or be secreted into the medium by simply changing the incubation conditions and the concentration of the inducer. The ratio between soluble antibody fragments and insoluble scFv aggregates proved to be dependent on the strength of the promoter. Lowering the incubation temperature below 20°C had no effect on the yield of soluble antibody fragments in the periplasm, but they were no longer secreted into the medium. An example of high level production in shake-flask cultures and one-step purification by immobilized metal affinity chromatography (IMAC) is described for a soluble scFv specific for the T cell surface antigen CD3. The biological activity of the purified anti-CD3 scFv was demonstrated by flow cytometry. This method should be especially useful for the functional screening of a large number of clones in small-scale cultures.  相似文献   
20.
The aim of the study was to investigate if the stretch reflex of the soleus muscle was useful in quantifying upper motor neuron lesions. The soleus stretch reflex was recorded in 10 healthy subjects and 20 patients with active relapsing-remitting multiple sclerosis and correlated to the number of MRI lesions in cerebrum and clinical scores (expanded disability status scale and regional functional scoring system). The short latency stretch reflex was elicited by rotating the left ankle joint 4 degrees with a rise time in the interval of 40-640 ms. The amplitude of the stretch was larger in multiple sclerosis patients being 88.5 microV in patients and 12.8 microV in controls, P = 0.007. The sensitivity of the stretch reflex expressed as the slope of the best linear fit was increased in MS patients to 2.6 microVs/degree compared with 0.6 microVs/degree (0.1-2.2) in controls, P = 0.009. There was no correlation between amplitude of the stretch reflex and number of MRI lesions (r = -0.03). In conclusion, the soleus stretch reflex might be useful to quantify spasticity but is not useful in detecting dysfunction of upper motor neurons in MS.  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