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   767篇
  免费   72篇
  国内免费   9篇
耳鼻咽喉   2篇
儿科学   41篇
妇产科学   10篇
基础医学   68篇
口腔科学   23篇
临床医学   131篇
内科学   182篇
皮肤病学   54篇
神经病学   19篇
特种医学   121篇
外科学   75篇
综合类   12篇
预防医学   43篇
眼科学   3篇
药学   14篇
肿瘤学   50篇
  2023年   8篇
  2022年   3篇
  2021年   6篇
  2020年   8篇
  2019年   8篇
  2018年   16篇
  2017年   15篇
  2016年   27篇
  2015年   19篇
  2014年   33篇
  2013年   31篇
  2012年   21篇
  2011年   24篇
  2010年   34篇
  2009年   52篇
  2008年   22篇
  2007年   19篇
  2006年   26篇
  2005年   25篇
  2004年   25篇
  2003年   24篇
  2002年   14篇
  2001年   11篇
  2000年   7篇
  1999年   14篇
  1998年   38篇
  1997年   34篇
  1996年   38篇
  1995年   26篇
  1994年   26篇
  1993年   31篇
  1992年   10篇
  1991年   9篇
  1990年   8篇
  1989年   17篇
  1988年   18篇
  1987年   26篇
  1986年   14篇
  1985年   8篇
  1984年   7篇
  1983年   5篇
  1982年   3篇
  1981年   9篇
  1980年   5篇
  1978年   4篇
  1977年   4篇
  1976年   5篇
  1975年   2篇
  1974年   2篇
  1963年   2篇
排序方式: 共有848条查询结果,搜索用时 31 毫秒
51.
52.
53.
OBJECTIVE: Magnetic resonance imaging (MRI) has been shown to be more sensitive than radiography for detecting bone erosions in rheumatoid arthritis (RA). Semiquantitative scoring based on visual image assessment has been introduced. However, there is considerable interest in true quantitative measures, particularly in the context of clinical trials designed to show differences between treatment groups. This study was undertaken to investigate the use of a new quantitative approach, multispectral (MS) image analysis, for assessing erosive change. METHODS: T1-weighted spin-echo (SE) and fat-suppressed gradient-echo (GE) sequences of metacarpophalangeal joints of the dominant hand were acquired at various time points throughout a 2-year period. MS analysis was applied to all images, resulting in segmentation into a generalized bone and a soft tissue class. Voxel changes from one to the other class identified apparent bone lesion volume change (Delta BLV). MR images were also visually scored for erosions (E score). All analyses were performed separately, on a per-joint basis, for short-term and long-term data sets. RESULTS: Analysis of variance with adjustment for individual effect revealed similar results in the short-term and the long-term studies, using either GE or SE images for visual assessment. Patients with an increase in E score on visual assessment had a significantly higher Delta BLV than those without. CONCLUSION: Temporal MS analysis of MRIs can be used to detect and quantify erosive changes in RA. This semiautomated method may be useful for demonstrating differences between treatment groups in clinical trials.  相似文献   
54.
55.
A 10‐year‐old male with acute leukemia presented with post‐chemotherapy anemia. During red cell transfusion, he developed hemoglobinuria. Transfusion reaction workup was negative. Drug‐induced immune hemolytic anemia was suspected because of positive direct antiglobulin test, negative eluate, and microspherocytes on smear pre‐ and post‐transfusion. Drug studies using the indirect antiglobulin test were strongly positive with trimethoprim and trimethoprim–sulfamethoxazole but negative with sulfamethoxazole. The patient recovered after discontinuing the drug, with no recurrence in 2 years. Other causes of anemia should be considered in patients with worse‐than‐expected anemia after chemotherapy. Furthermore, hemolysis during transfusion is not always a transfusion reaction. Pediatr Blood Cancer. 2010;55:1201–1203. © 2010 Wiley‐Liss, Inc.  相似文献   
56.
Aim: To analyse the main prenatal and postnatal features of congenital chylothorax (CC), and the outcome including mid‐term follow‐up. Methods: We searched our databases for CC diagnosed between 1990 and 2006. Data of 29 cases were retrieved and analysed. Follow‐up until 3 years of age was available for all patients. Results: Most patients were diagnosed prenatally (94%) and most cases were complicated by foetal hydrops (66.7%). The overall survival rate at 3 years was 56%. A significantly poorer outcome was observed when foetal hydrops, preterm birth < 34 weeks, large effusions and/or early‐onset pneumothorax were present. An important but not significant improvement in the survival rate was observed through the study period; while in 1990–1998, the survival rate was 41.7%, from 1999 to 2006 it was 66.7% (p = 0.19). In the mid‐term follow‐up, we did not observe any recurrence of CC and most infants remain asymptomatic. However, 27% of survivors were diagnosed as having asthma in early infancy. Conclusion: CC still carries a significant risk of perinatal mortality. However, continuous advances in foetal and neonatal medicine are improving the prognosis of these patients, and nowadays most of them are likely to survive. Beyond the neonatal period, most survivors have an uneventful outcome.  相似文献   
57.
Spontaneously occurring genetic lysosomal storage diseases are as rare in other mammalian species as in man. However, the advent of gene targeting technology has revolutionized the state of animal models of genetic diseases. Nearly all lysosomal storage diseases known in man have been duplicated in the mouse. The technology now allows, not only complete inactivation of endogenous genes, but also the introduction of essentially any type of mutation. These animal models can overcome many of the limitations inherent in studies of human patients - rarity of the disease, extremely complex genetic background and logistical and ethical constraints in the design and execution of experiments with human subjects. For example, genetic manipulations of germ cells or cross-breeding experiments between two mutants are readily feasible with animal models. Two major areas of the utility of animal models are the clarification of the pathophysiology/pathogenetic mechanism of disease and the exploration of therapeutic approaches. Examples of experiments using animal models of lysosomal storage disease are presented, primarily from studies undertaken in our own laboratory.
Conclusion : Animal models have proved invaluable in extending our knowledge of the lysosomal storage diseases and exploring potential therapies.  相似文献   
58.

The sexual practices, partner communication patterns, and prevalence of chlamydial infection were determined in a sample of college women. Specific inclusion criteria were used to screen 146 participants. The presence of a mucopurulent cervical discharge was the only criterion significantly associated with infection. Only 12% of the sample used condoms alone or in combination with another birth control method, and only 31% of the women discussed with their partner their own or their partner's sexual history. Thirty‐eight percent of the sample reported a history of one to four episodes of a sexually transmitted disease, and 21% of the women stated they had had two or more sexual partners within the past 6 months. Health providers, counselors, and women themselves must address this health issue with more assertive behavior and communication skills.  相似文献   
59.
The purpose of this article is to outline the criticality of water supply in sustained operations of healthcare facilities, particularly during community emergencies, and to advocate for enhanced cross‐sector support from the water utilities in meeting this need. Information and ideas presented here were developed in the course of a regional project sponsored by the Metropolitan Washington Council of Governments (MWCOG) for development of emergency water supply operations plans for critical water uses in the Washington, DC, area.  相似文献   
60.
In a study carried out in the Ghassreghand Division (Baluchistan, Iran) from March through November 1995, efficacy of cyfluthrin-impregnated bednets was compared to that of untreated nets, in relation to malaria control. Ten villages with a total population of 4,572 and 3 villages with a total population of 1,935 were used as treatment and control, respectively. The collection, impregnation (target dosage of 40 mg active ingredient [AI]/m2), and redistribution of the nets (9% nylon, 52% light cotton, 30% medium cotton, and 9% heavy cotton), carried out in mid-April, were done by local health workers, supervised by the senior research staff. Anopheles culicifacies was considered to be the main vector of malaria in the named area. This species is mainly zoophilic, endophilic, and exophagic. The initial uptake of the insecticide was lower than the target dosage, with high variation (nylon, 12.5 +/- 5.4 mg AI/m2; light cotton, 33.3 +/- 26.1 mg AI/m2; medium cotton, 25.9 +/- 20 mg AI/m2; heavy cotton, 17.6 +/- 12.5 mg AI/m2). The use of impregnated mosquito nets (used primarily outside) had no significant effect on the incidence of malaria. No difference was detected in the parasite density of patients with positive slides. No significant effect was observed in the parous rate, human blood index, and sporozoite rate of anopheline vectors. Only the indoor resting densities of An. culicifacies and other malaria vectors were drastically reduced after the introduction of the cyfluthrin-impregnated nets into the treatment villages. The residual activity of cyfluthrin was lower than expected. The mortality of anophelines brought in contact with the treated nets for 3 min in bioassays dropped to less than 55% in 3 months. The loss of chemical activity was greatest for the light cotton nets, followed by the medium cotton nets. Cyfluthrin-treated nets were mildly irritating to host-seeking female anophelines in the laboratory. The protective rate of impregnation (all fabric kinds included) in preventing female mosquitoes from biting through the impregnated nets was initially 5-6 times that of the nonimpregnated nets. The study did not detect any significant difference between the use of untreated versus impregnated bednets in the Ghassreghand area. In planning future medium-scale trials, comparison of new compounds and formulations to the more widely used pyrethroids such as permethrin and deltamethrin is highly recommended.  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