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   322篇
  免费   12篇
  国内免费   1篇
耳鼻咽喉   4篇
儿科学   22篇
妇产科学   12篇
基础医学   50篇
口腔科学   13篇
临床医学   22篇
内科学   64篇
皮肤病学   4篇
神经病学   16篇
特种医学   44篇
外科学   45篇
综合类   8篇
预防医学   8篇
眼科学   1篇
药学   17篇
  1篇
肿瘤学   4篇
  2017年   5篇
  2015年   5篇
  2014年   4篇
  2013年   9篇
  2010年   3篇
  2009年   4篇
  2007年   5篇
  2005年   4篇
  2004年   5篇
  2001年   2篇
  1999年   2篇
  1998年   16篇
  1997年   7篇
  1996年   12篇
  1995年   7篇
  1994年   10篇
  1993年   10篇
  1992年   3篇
  1990年   7篇
  1989年   11篇
  1988年   8篇
  1987年   11篇
  1986年   12篇
  1985年   4篇
  1984年   5篇
  1983年   4篇
  1982年   2篇
  1981年   2篇
  1980年   5篇
  1979年   3篇
  1978年   6篇
  1977年   5篇
  1976年   2篇
  1973年   3篇
  1972年   5篇
  1970年   2篇
  1969年   2篇
  1967年   2篇
  1966年   4篇
  1965年   2篇
  1963年   2篇
  1959年   9篇
  1958年   17篇
  1957年   16篇
  1956年   14篇
  1955年   13篇
  1954年   13篇
  1949年   6篇
  1948年   8篇
  1947年   2篇
排序方式: 共有335条查询结果,搜索用时 0 毫秒
61.
62.
63.
Inversion recovery (IR), commonly considered a pulse sequence capable of producing T1-weighted images with excellent display of normal anatomy, is versatile: The null point and peak time provide a useful, succinct summary of the properties of IR and its capacity for producing both T1- and T2-weighted images. Shortening of the inversion time (TI) and creation of a short-TI inversion-recovery (STIR) pulse sequence increases sensitivity to malignancy and other abnormalities by making the effects of prolonged T1 and T2 on signal intensity additive and by nulling the signal from fat. The authors examined over 300 patients with various malignancies and compared STIR images with T1- and T2-weighted images obtained at 0.5 T. In 43 cases, signal-difference-to-noise ratios (SD/Ns) were calculated between tumor, fat, and muscle. In general, STIR images demonstrated tumor as a conspicuously high-intensity area in a background of muted, discernible anatomic detail. The good contrast achieved with STIR sequences between tumor and fat (SD/N = 18.1) and tumor and muscle (SD/N = 12.9) consolidated into a single image the information contained separately on T1- and T2-weighted images, which facilitates efficient detection and localization of malignancy.  相似文献   
64.
Although more widespread screening and routine adjuvant therapy has improved the outcome for breast cancer patients in recent years, there remains considerable scope for improving the efficacy, safety and tolerability of adjuvant therapy in the early stage disease and the treatment of advanced disease. Toremifene is a selective estrogen receptor modifier (SERM) that has been widely used for decades in hormone receptor positive breast cancer both in early and late stage disease. Its efficacy has been well established in nine prospective randomized phase III trials compared to tamoxifen involving more than 5500 patients, as well as in several large uncontrolled and non-randomized studies. Although most studies show therapeutic equivalence between the two SERMs, some show an advantage for toremifene. Several meta-analyses have also confirmed that the efficacy of toremifene is at least as good as that of tamoxifen. In terms of safety and tolerability toremifene is broadly similar to tamoxifen although there is some evidence that toremifene is less likely to cause uterine neoplasms, serious vascular events and it has a more positive effect on serum lipids than does tamoxifen. Toremifene is therefore effective and safe in the treatment of breast cancer. It provides not only a useful therapeutic alternative to tamoxifen, but may bring specific benefits.  相似文献   
65.
T-Cell Recognition of Measles Virus Haemagglutinin Studied in a Mouse Model   总被引:1,自引:0,他引:1  
BALB/c mice were pretreated with cyclophosphamide and immunized 2 days later with inactivated, purified measles virus (MV) mixed with dimethyl dioctadecyl ammonium bromide (DDA). Seven days later, lymph nodes (LN) were removed and lymphocytes cultured in the presence of purified MV antigens. MV haemagglutinin (H) was found to be a major antigen responsible for proliferation of the lymphocytes. Incorporation of purified H into liposomes significantly enhanced the proliferative response compared with purified H alone. Response to MV nucleocapsid protein was only moderate, and insertion of this protein into liposomes did not improve the response. As an attempt to analyse T-cell epitopes of MV H, three synthetic peptides previously found to elicit a strong antibody response were used both as priming and stimulating antigens. None of the peptides was able to elicit a secondary response when MV-primed LN cells were stimulated in vitro. However, each peptide primed T cells for a secondary challenge with purified, inactivated MV, which was demonstrated by proliferation and a delayed-type hypersensitivity assay and also by transfer experiments with peptide-primed cells.  相似文献   
66.
A 43-year-old man presented with loose stools, abdominal pain and a weight loss of 15 kg. Investigations revealed a pancreatic insufficiency and an enteropathy with villous atrophy. Coeliaki was suspected. In spite of treatment with a gluten-free diet in hospital the patient did not improve and the villous atrophy remained unchanged. Other causes than coeliaki to villous atrophy were ruled out. The patient had a heavy consumption of alcohol and after prolonged abstinence the patient gained weight, the pain disappeared and the stools were normalized. The jejunal biopsy was now normal. This case report raises the possibility that enteropathy and villous atrophy may be causally related to alcohol overconsumption.  相似文献   
67.
A new technique is described that allows for the creation of pure pulsatile flow magnetic resonance (MR) images in a single acquisition. Five to 16 electrocardiographically gated images spanning the entire cardiac cycle are obtained with use of a gradient-echo pulse sequence. The section can be varied from 4 mm thick to full thickness projection. Taken singly, each image provides direct assessment of flow direction and velocity. Subtraction of image pairs eliminates signal detected from stationary protons, producing images of pulsatile flow. In this study the technique was used to image the flow of cerebrospinal fluid (CSF) in healthy subjects and in one patient with syringohydromyelia. The data suggest that multiphasic MR imaging provides a powerful means for the noninvasive assessment of CSF pulsatile flow dynamics and may have potential clinical application for the investigation of a variety of abnormalities such as normal pressure hydrocephalus, syrinx, and spinal block.  相似文献   
68.
69.
Forty-six asthmatics with verified allergy to the house dust mite, D. pteronyssinus (Dp), participated in a double-blind study comparing the effect of 2 years' hyposensitization with two different Dp extracts. Two groups received either monomethoxypolyethylene glycol modified (mPEG) Dp extract or the corresponding non-modified extract, and a third group acted as controls receiving no injections. Medicine consumption, symptom scores, and peak expiratory flow (PEF) were recorded daily from September to December prior to and after 6 and 18 months of treatment. Changes were calculated choosing changes greater than or equal to 10% as relevant. In addition, patients were asked to give their direct assessment of the clinical effect at the end of the study. After 6 months, there was an improvement in symptoms + medication in 11/14 of Dp-treated, 6/17 of the mPEG-Dp group (P greater than 0.05) and 3/15 of openly treated controls. Few patients had changed in PEF. During the second year, several Dp-treated relapsed and some controls improved. At the end of the study the same improvement rate was seen in all groups. Similarly, the retrospective questionnaire data did not disclose any significant differences between groups after 2 years. In conclusion, hyposensitization with unmodified Dp extract seemed to have a favourable short-term effect on bronchial symptoms + medication in the majority of patients. When mainly on maintenance dose, the beneficial effect was reduced. The mPEG modification of the extract had reduced not only allergenicity but also the clinical effect of equal doses. Changes in medicine and symptom scores only partly correlated to retrospective assessment, thus stressing the problems in this kind of evaluation.  相似文献   
70.
We have studied the effect of surgical injury on cutaneous sensitivityand somatosensory evoked potentials (SSEP) to dermatomal electricalstimulation in 10 patients undergoing hysterectomy. Forty-eighthours after surgery, sensory threshold increased from 2.2 (SEM0.3) mA to 4.4 (1.1) mA (P < 0.01) and SSEP amplitudes inP1, N1, P2 and the peak-to-peak amplitudes decreased (P <0.05). Latency was prolonged only in the N3 component (P <0.05). No changes were seen in threshold and SSEP in a controlgroup studied over the same interval. The results suggest thatsurgical injury activates antinociceptive modulatory systems.  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