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   438篇
  免费   53篇
  国内免费   5篇
耳鼻咽喉   8篇
儿科学   17篇
妇产科学   16篇
基础医学   67篇
口腔科学   5篇
临床医学   70篇
内科学   75篇
皮肤病学   4篇
神经病学   31篇
特种医学   6篇
外科学   61篇
综合类   8篇
预防医学   42篇
眼科学   6篇
药学   21篇
中国医学   1篇
肿瘤学   58篇
  2024年   1篇
  2023年   11篇
  2022年   8篇
  2021年   16篇
  2020年   15篇
  2019年   24篇
  2018年   26篇
  2017年   26篇
  2016年   17篇
  2015年   17篇
  2014年   14篇
  2013年   24篇
  2012年   28篇
  2011年   34篇
  2010年   13篇
  2009年   11篇
  2008年   36篇
  2007年   25篇
  2006年   24篇
  2005年   27篇
  2004年   14篇
  2003年   23篇
  2002年   12篇
  2001年   2篇
  2000年   2篇
  1999年   3篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   2篇
  1994年   5篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1982年   2篇
  1979年   5篇
  1978年   3篇
  1977年   2篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
排序方式: 共有496条查询结果,搜索用时 31 毫秒
1.
Cyclotron-produced copper-64 radioisotope tracers offer the possibility to perform both diagnostic investigation by positron emission tomography (PET) and radiotherapy by a theranostic approach with bifunctional chelators. The versatile chemical properties of copper add to the importance of this isotope in medicinal investigation. [64Cu][Cu (ATSM)] has shown to be a viable candidate for imaging of tumor hypoxia; a critical tumor microenvironment characteristic that typically signifies tumor progression and resistance to chemo-radiotherapy. Various production and radiosynthesis methods of [64Cu][Cu (ATSM)] exist in labs, but usually involved non-standardized equipment with varying production qualities and may not be easily implemented in wider hospital settings. [64Cu][Cu (ATSM)] was synthesized on a modified GE TRACERlab FXN automated synthesis module. End-of-synthesis (EOS) molar activity of [64Cu][Cu (ATSM)] was 2.2–5.5 Ci/μmol (HPLC), 2.2–2.6 Ci/μmol (ATSM-titration), and 3.0–4.4 Ci/μmol (ICP-MS). Radiochemical purity was determined to be >99% based on radio-HPLC. The final product maintained radiochemical purity after 20 h. We demonstrated a simple and feasible process development and quality control protocols for automated cyclotron production and synthesis of [64Cu][Cu (ATSM)] based on commercially distributed standardized synthesis modules suitable for PET imaging and theranostic studies.  相似文献   
2.
Using the agar dilution technique, 231 strains of Bacteroides fragilis, isolated during a 2-year period from human infections, were identified at subspecies level and were tested for susceptibility to 13 beta-lactam antibiotics. The penicillins were benzylpenicillin, ampicillin, carbenicillin, cloxacillin, and the recently described penicillin derivatives cyclacillin, ticarcillin, and PC-904. The following cephalosporin derivatives were tested: cephaloridine, cephalothin, cephalexin, cefamandole and cefuroxime. The cephamycin C derivative cefoxitin was also included in the study. Cefoxitin was the most effective drug tested since more than 80% of the strains were inhibited by 8 microgram/ml or less, and no strain had a minimal inhibitory concentration (MIC) of more than 64 microgram/ml. There was no marked difference in sensitivity among the subspecies with exception of subspecies vulgatus, which was slightly more sensitive to all antibiotics tested. The size of the inoculum was an important factor for obtaining reproducible results in the sensitivity tests. Increased inocula resulted in markedly higher MICs for cephaloridine and cefuroxime. Production of beta-lactamase was performed on all isolates by a chromogenic cephalosporin substrate and about 90% of the strains were found to be beta-lactamase producers.  相似文献   
3.
We investigated the ability of staphylococcal enterotoxin B (SEB) to modify the immediate hypersensitivity response induced in BALB/c mice following sensitization to ovalbumin (OVA), a response mediated by OVA-reactive Vβ8 T cells. Mice were sensitized by skin painting with OVA every second day over a period of 2 weeks. SEB, a potent activator of Vβ8+ T cells, was administered at the same site where OVA was applied (skin of the lower abdomen) following two different protocols. In protocol (A) SEB was injected intradermally 1 day before painting with OVA and on day 7; in protocol B, SEB was injected each time OVA was applied to the skin (eight times). SEB (but not SEA) altered the development of immediate hypersensitivity to OVA, as demonstrated by the reduction in allergen-specific IgE, decreased OVA-specific immediate skin test responsiveness, and prevented the development of increased airways responsiveness after bronchial challenge with OVA. Injections of SEB did not alter the proliferative responses of local draining lymph node cells or spleen mononuclear cells to OVA, indicating that administration of SEB did not inhibit the sensitization to OVA, but shifted the immune response away from an immediate type response (IgE/IgG1) to IgG2a, IgG2b and IgG3. Although both protocols of SEB treatment did not lead to a major deletion of the Vβ8 T cell population, they did reduce the proliferative response of Vβ8+ T cells to OVA. These data indicate that the bacterial toxin SEB is capable of modifying the immediate hypersensitivity response induced by OVA by altering the functional capacity of antigen-reactive Vβ8 T cells.  相似文献   
4.
Campylobacteriosis is a disease of worldwide importance, but aspects of its transmission dynamics, particularly risk factors, are still poorly understood. We used data from a matched case-control study of 4,269 men who have sex with men (MSM) and 26,215 controls, combined with national surveillance data on Campylobacter spp., Salmonella spp., and Shigella spp., to calculate matched odds ratios (mORs) for infection among MSM and controls. MSM had higher odds of Campylobacter (mOR 14, 95% CI 10–21) and Shigella (mOR 74, 95% CI 27–203) infections, but not Salmonella (mOR 0.2, 95% CI 0–13), and were less likely than controls to have acquired Campylobacter infection abroad (χ2 = 21; p<0.001). Our results confirm that sexual contact is a risk factor for campylobacteriosis and also suggest explanations for unique features of Campylobacter epidemiology. These findings provide a baseline for updating infection risk guidelines to the general population.  相似文献   
5.
6.
We aimed to compare the antidepressant and anxiolytic effects, tolerability and effects on quality of life of mirtazapine and citalopram in a randomized, double-blind, multicentre, 8-week study. Patients with a Major Depressive Episode (DSM-IV) and a baseline score of > or = 22 on the Montgomery-Asberg Depression Rating Scale (MADRS) were randomized to 8 weeks treatment with either mirtazapine (n = 137, 15-60 mg/day) or citalopram (n = 133, 20-60 mg/day). Efficacy was evaluated by the MADRS, Hamilton Anxiety Scale (HAM-A), Clinical Global Impression scales (CGI), the Leeds Sleep Evaluation Questionnaire (LSEQ) and Quality of Life Enjoyment and Satisfaction Questionnaire (QLESQ). The efficacy analyses were performed on the Intent-To-Treat Group using the Last Observation Carried Forward method. Vital signs and laboratory variables are measured and adverse events recorded at each weekly visit. The magnitude of reduction from baseline in group mean MADRS scores was large in both groups, reaching after 8 weeks of treatment mean scores of 9.1 in the mirtazapine group and 8.9 in the citalopram group. Both treatments also resulted in a substantial improvement in anxiety symptoms, sleep disturbances and quality of life, and high percentage of responders. However, at day 14, statistically significantly larger magnitudes of change favouring mirtazapine were present in the group mean MADRS, HAM-A and CGI-Severity of illness and Quality of life scores. A difference of 2.3 points on MADRS favouring mirtazapine is considered indicative for a clinically relevant superiority between two proven antidepressants. Mirtazapine treatment was also related to faster improvement of sleep, quality of sleep and improved alertness following awakening, as shown by statistically significant differences on the self-rating LSEQ at various time points. There were no differences between two treatment groups on self-rating QLSEQ. Both drugs were well tolerated, with a low number of patients in either group prematurely terminating the study due to adverse events (mirtazapine: 3.6%, citalopram, 3.0%). Sweating and nausea were statistically significantly more frequent in the citalopram group and increased appetite and complaints of weight increase in the mirtazapine group. There were no clinically relevant changes in laboratory parameters and vital sign variables with either treatment, except for clinically relevant increase in body weight, occurring more frequently in mirtazapine patients. In this study, mirtazapine and citalopram were equally effective in reducing symptoms of depression and anxiety, and well tolerated. However, mirtazapine was significantly more effective than citalopram after 2 weeks of treatment on the MADRS, HAM-A and CGI Severity of illness and Quality of life scales. This finding, consistently present at all major efficacy variables, suggests potentially faster onset of efficacy of mirtazapine over citalopram.  相似文献   
7.
8.
9.
10.
We study methods for how to include the spatial distribution of tumours when investigating the relation between brain tumours and the exposure from radio frequency electromagnetic fields caused by mobile phone use. Our suggested point process model is adapted from studies investigating spatial aggregation of a disease around a source of potential hazard in environmental epidemiology, where now the source is the preferred ear of each phone user. In this context, the spatial distribution is a distribution over a sample of patients rather than over multiple disease cases within one geographical area. We show how the distance relation between tumour and phone can be modelled nonparametrically and, with various parametric functions, how covariates can be included in the model and how to test for the effect of distance. To illustrate the models, we apply them to a subset of the data from the Interphone Study, a large multinational case‐control study on the association between brain tumours and mobile phone use. Copyright © 2015 John Wiley & Sons, Ltd.  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