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   993篇
  免费   71篇
  国内免费   2篇
耳鼻咽喉   7篇
儿科学   23篇
妇产科学   38篇
基础医学   153篇
口腔科学   40篇
临床医学   85篇
内科学   219篇
皮肤病学   89篇
神经病学   41篇
特种医学   95篇
外科学   100篇
综合类   12篇
预防医学   38篇
眼科学   2篇
药学   48篇
中国医学   4篇
肿瘤学   72篇
  2023年   6篇
  2022年   5篇
  2021年   24篇
  2020年   15篇
  2019年   16篇
  2018年   21篇
  2017年   16篇
  2016年   14篇
  2015年   26篇
  2014年   27篇
  2013年   46篇
  2012年   50篇
  2011年   50篇
  2010年   33篇
  2009年   21篇
  2008年   27篇
  2007年   45篇
  2006年   38篇
  2005年   34篇
  2004年   44篇
  2003年   27篇
  2002年   26篇
  2001年   35篇
  2000年   21篇
  1999年   34篇
  1998年   27篇
  1997年   18篇
  1996年   21篇
  1995年   22篇
  1994年   12篇
  1993年   25篇
  1992年   24篇
  1991年   15篇
  1990年   15篇
  1989年   24篇
  1988年   16篇
  1987年   15篇
  1986年   8篇
  1985年   14篇
  1984年   7篇
  1983年   9篇
  1980年   9篇
  1978年   7篇
  1976年   7篇
  1975年   5篇
  1971年   6篇
  1969年   6篇
  1957年   6篇
  1955年   4篇
  1954年   5篇
排序方式: 共有1066条查询结果,搜索用时 171 毫秒
981.
982.
983.
984.
985.
986.
Evaluation was carried out on the action of different antibiotics on the release of cytokines. Experiments were done in vitro on monocytes and on human lymphocytes. Results show that the majority of the antibiotics tested are able to induce the release of one or more cytokines from their respective producing cells. Among the beta-lactams the most active were the cephalosporins (cephalexin, cefamandol, ceftazidin, and a sulbactam-ampicillin combination) in inducing the release of TNF, IL-1 alpha, and IL-6 from monocytes, and releasing IL-4 and IFN-tau from lymphocytes. The sulbactam-ampicillin combination and cefamandole were extremely active in the production of IFN-tau. Among the lincosamides, clindamycine notably stimulated the release of TNF and IL-6, while lincomycine induced a notable increment of IL-4 from monocytes. Teicoplanin is a very strong inducer of TNF, IL-1 alpha and IL-6.  相似文献   
987.
Frozen-thawed embryo transfer is an effective procedure that allows further possibilities of pregnancy in addition to those obtained after the fresh in vitro fertilization (IVF). In our follow-up study we analysed all fresh embryo transfer procedures and every frozen-thawed embryo transfer performed from January 2000 to December 2001 evaluating the cumulative pregnancy rates. The study population was divided into two groups according to the female age: <38 years (group I) and >38 years (group II). All the best embryos were chosen for transfer and all the supernumerary good quality embryos were cryopreserved on the day of transfer. The embryos were then thawed and manipulated using a new technique. In group I, 527 patients (619 cycles) underwent fresh embryo transfer and in 232 of them (238 cycles) the embryos were frozen (44% per patients and 38.4% per cycle). In group II, 156 patients (193 cycles) underwent fresh embryo transfer and in 14 of them (15 cycles) the embryos were frozen (9% per patient and 7.8% per cycle). The pregnancy rate of group I patients that had their supernumerary embryos frozen (232 patients and 238 cycles) was 47.4% per cycle and 48.7% per patient whereas in the same population of group II patients (14 patients and 15 cycles) the clinical pregnancy rate was 35.7% per cycle and 38.5% per patients. The cumulative clinical pregnancy rate after transfer of fresh and thawed embryos was: group I, 74% per cycle and 76% per patients; group II, 42.8% per cycle and 46.1% per patient. Frozen-thawed embryo transfer is a cost-effective practice.  相似文献   
988.
989.
Management of poor responders in IVF   总被引:6,自引:0,他引:6  
Correct controlled ovarian stimulation is of paramount importance in assisted reproductive technologies. Therefore, analysis of the ovarian reserve of the patient is mandatory to tailor the best ovarian stimulation regimen. When the ovarian reserve is reduced, the induction of a multifollicular growth remains a challenge. Several factors could be associated with reduced ovarian response. However, reduced ovarian reserve either in older patients or in young patients represents the most frequent aetiological factor. Whatever is the aetiology, one of the main problems is how to predict a reduced ovarian response, and although several tests have been suggested, no very accurate predictive test is available. A variety of different stimulation protocols have been suggested but the lack of any large-scale, prospective, randomized, controlled trials of the different management strategies and the lack of a uniform definition of the population may result in comparisons of heterogeneous groups of patients, making it difficult to draw any definitive conclusions. Natural cycle IVF may represent an easy and cheap approach in the management of this group of patients. Although no controlled large prospective randomized studies are available to compare the natural IVF procedure with ovarian stimulation IVF in poor responder patients, the efficacy of natural cycle IVF is hampered by high cancellation rates mainly due to untimely LH surge. The use of gonadotrophin-releasing hormone antagonists in the late follicular phase, which reduces the premature LH rise rate, and the improvements in laboratory conditions and fertilization techniques, increase the embryo transfer rates, making this procedure more cost-effective.  相似文献   
990.
BACKGROUND: Dermoscopy used by experts has been demonstrated to improve the diagnostic accuracy for melanoma. However, little is known about the diagnostic validity of dermoscopy when used by nonexperts. OBJECTIVE: To evaluate the diagnostic performance of nonexperts using a new 3-point checklist based on a simplified dermoscopic pattern analysis. METHODS: Clinical and dermoscopic images of 231 clinically equivocal and histopathologically proven pigmented skin lesions were examined by 6 nonexperts and 1 expert in dermoscopy. For each lesion the nonexperts assessed 3 dermoscopic criteria (asymmetry, atypical network and blue-white structures) constituting the 3-point method. In addition, all examiners made an overall diagnosis by using standard pattern analysis of dermoscopy. RESULTS: Asymmetry, atypical network and blue-white structures were shown to be reproducible dermoscopic criteria, with a kappa value ranging from 0.52 to 0.55. When making the overall diagnosis, the expert had 89.6% sensitivity for malignant lesions (tested on 68 melanomas and 9 pigmented basal cell carcinomas), compared to 69.7% sensitivity achieved by the nonexperts. Remarkably, the sensitivity of the nonexperts using the 3-point checklist reached 96.3%. The specificity of the expert using overall diagnosis was 94.2% compared to 82.8 and 32.8% achieved by the nonexperts using overall diagnosis and 3-point checklist, respectively. CONCLUSION: The 3-point checklist is a valid and reproducible dermoscopic algorithm with high sensitivity for the diagnosis of melanoma in the hands of non-experts. Thus it may be applied as a screening procedure for the early detection of melanoma.  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