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   520篇
  免费   31篇
  国内免费   3篇
耳鼻咽喉   3篇
儿科学   14篇
妇产科学   15篇
基础医学   87篇
口腔科学   16篇
临床医学   62篇
内科学   79篇
皮肤病学   7篇
神经病学   44篇
特种医学   52篇
外科学   79篇
综合类   4篇
预防医学   16篇
眼科学   4篇
药学   18篇
中国医学   2篇
肿瘤学   52篇
  2024年   2篇
  2023年   6篇
  2022年   6篇
  2021年   20篇
  2020年   6篇
  2019年   14篇
  2018年   28篇
  2017年   15篇
  2016年   9篇
  2015年   12篇
  2014年   21篇
  2013年   21篇
  2012年   36篇
  2011年   42篇
  2010年   24篇
  2009年   15篇
  2008年   41篇
  2007年   30篇
  2006年   28篇
  2005年   23篇
  2004年   30篇
  2003年   28篇
  2002年   19篇
  2001年   8篇
  2000年   3篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1996年   3篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   4篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   1篇
  1987年   5篇
  1986年   4篇
  1985年   1篇
  1984年   2篇
  1983年   2篇
  1982年   2篇
  1981年   5篇
  1980年   6篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1937年   2篇
  1936年   1篇
排序方式: 共有554条查询结果,搜索用时 13 毫秒
541.
542.
543.
[Purpose] The physical strength elements required for athletic throwing events include muscle strength, swiftness, agility, speed, flexibility, and physical balance. Although plyometric training and weight training are implemented as representative training methods for improving swiftness and agility, most studies of it have been conducted with players of other sports. [Subjects] The study subjects were 10 throwing event athletes attending K physical education high school. The subjects were randomly assigned to a control group of five subjects and an experimental group of five subjects. To analyze the body composition, an Inbody 3.0 instrument (Biospace, Korea) was used as experimental equipment to measure heights, weight, body fat percentages, and muscle masses and a Biodex system 4.0 (BIODEX, USA) was used to measure isokinetic muscle-joint and lumbar muscle strengths. The plyometric training consisted of 15 techniques out of the training methods introduced in the ‘Power up plyometric training’. The plyometric program was implemented without any training load three times per week during daybreak exercises for the experimental group. The number of times and the number of sets were changed over time as follows: three sets of 10 times in the 1st −4th weeks, three sets of 15 times in the 5th–8th weeks, and five sets of 15 times in the 9th−12th weeks. [Results] According to the ANCOVA results of lumbar extensor muscle strength at 60°/sec, the overall reliability of the model was significant. According to the ANCOVA results of lumbar flexor muscle strength at 60°/sec, the overall reliability of the model was significant. [Conclusion] Plyometric training positively affected high school throwing event athletes. To summarize the study findings, the application of plyometric training with high intensity and loads improved the results of athletes who perform highly intensive exercises at normal times.Key words: Plyometric, Lumbar extensor, Throwing athletic  相似文献   
544.
Thyroid cancer incidence was studied in the cohort of residents of Ozyorsk and Kyshtym, the nearest upwind cities to the Mayak Production Association (Mayak PA), Russia's first plutonium production facility, which has been in operation since 1948. Radioactive contamination of areas around the Mayak PA were from unmonitored releases of inert gases produced by industrial reactors and also from the release of uranium fission products from a radiochemical plant stack where irradiated uranium blocks were refined. Iodine-131 (131I) was the main contributor to the technogenic dose from atmospheric releases. Routine monitoring of gaseous releases began in the mid-1960s, when a gas purification system was perfected. Children were a critical group due to their higher radiosensitivity and specific diet (dairy products and vegetables). Both cities maintain Registries containing over 100,000 individuals born from 1934-2006. Among this group, more than 100 cases of thyroid cancer were registered during 1948-2009. The relative risk of thyroid cancer incidence is 1.5 times higher than in the Chelyabinsk.  相似文献   
545.
Sudden cardiac death (SCD) of an athlete is a rare but tragic event and sport activity might play a trigger role in athletes with underlying structural or electrical heart diseases. Preparticipation screenings (PPs) have been conceived for the potential to prevent SCD in young athletes by early identification of cardiac diseases. The European Society of Cardiology protocol for PPs includes history collection, physical examination and baseline electrocardiogram, while further examinations are reserved to individuals with abnormalities at first-line evaluation. Nevertheless, transthoracic echocardiography has been hypothesized to have a primary role in the PPs. This review aims to describe how to approach an athlete-focused echocardiogram, highlighting what is crucial to focus on for the different diseases (cardiomyopathies, valvulopathies, congenital heart disease, myocarditis and pericarditis) and when is needed to pay attention to overlap diagnostic zone (“grey zone”) with the athlete's heart. Once properly tested, focused echocardiography by sports medicine physicians may become standard practice in larger screening practices, potentially available during first-line evaluation.  相似文献   
546.

Objective

2-Fluorine-18-fluoro-2-deoxy-d-glucose positron emission tomography (18F-FDG PET) imaging is not considered useful for assessing bladder cancer due to the physiological uptake of 18F-FDG in the bladder. Despite reports of the detection of bladder cancer by washing out 18F-FDG from the bladder, such methods are invasive and impractical in the routine practice. The purpose of this study was to evaluate prospectively the utility of oral hydration with 500 mL of water and voiding-refilling, a minimally invasive method that we introduced to enable detection of residual invasive bladder cancer on delayed 18F-FDG PET imaging.

Methods

From January 2015 to December 2017, 267 consecutive patients with bladder cancer underwent 18F-FDG PET/computed tomography scans. Among these patients, 25 (19 men and 6 women; mean age, 72.0?±?11.3 years) were newly diagnosed as having muscle-invasive bladder cancer by transurethral resection of bladder tumor and T3b or T4 by magnetic resonance imaging (MRI). All patients were orally hydrated with only 500 mL of water and were then instructed to void frequently for 60 min before early 18F-FDG PET imaging. After the scans, they were instructed to hold their urine for 60 min. Then, delayed imaging was performed. Two radiologists evaluated the early and delayed 18F-FDG PET images to determine whether residual invasive bladder cancer could be detected. The maximum standardized uptake values (SUVmax) of the bladder urine and residual tumor site were also measured on early and delayed images. The maximum diameter of the primary bladder tumor was measured on MRI.

Results

The sensitivity for detecting residual invasive bladder cancer on early and delayed imaging were 24.0 and 92.0%, respectively (P?<?0.001). The SUVmax of the bladder urine on the early and delayed imaging were 34.7?±?29.7 and 16.0?±?10.7 (mean?±?SD), respectively. The SUVmax of the residual tumor site on the early and delayed imaging were range 15.65–30.83 and 10.06–45.70, respectively.

Conclusion

Delayed 18F-FDG PET imaging with oral hydration using only 500 mL of water and voiding-refilling is useful for detecting residual invasive bladder cancer.
  相似文献   
547.
Agents that can potentiate the efficacy of standard chemotherapy against pancreatic cancer are of great interest. Because of their low cost and safety, patients commonly use a variety of dietary supplements, although evidence of their efficacy is often lacking. One such commonly used food supplement is Zyflamend, a polyherbal preparation with potent anti-inflammatory activities and preclinical efficacy against prostate and oral cancer. Whether Zyflamend has any efficacy against human pancreatic cancer alone or in combination with gemcitibine, a commonly used agent, was examined in cell cultures and in an orthotopic mouse model. In vitro, Zyflamend inhibited the proliferation of pancreatic cancer cell lines regardless of p53 status and also enhanced gemcitabine-induced apoptosis. This finding correlated with inhibition of NF-κB activation by Zyflamend and suppression of cyclin D1, c-myc, COX-2, Bcl-2, IAP, survivin, VEGF, ICAM-1 and CXCR4. In nude mice, oral administration of Zyflamend alone significantly inhibited the growth of orthotopically transplanted human pancreatic tumors, and when combined with gemcitabine, further enhanced the antitumor effects. Immunohistochemical and Western blot analyses of tumor tissue showed that the suppression of pancreatic cancer growth correlated with inhibition of proliferation index marker (Ki-67), COX-2, MMP-9, NF-κB and VEGF. Overall, these results suggest that the concentrated multiherb product Zyflamend alone can inhibit the growth of human pancreatic tumors and, in addition, can sensitize pancreatic cancers to gemcitabine through the suppression of multiple targets linked to tumorigenesis.  相似文献   
548.
549.
Polyamines are naturally occurring polycations derived from amino acids via decarboxylation by ornithine decarboxylase (ODC). Ornithine is a substrate for ODC; decarboxylation of ornithine is inhibited by difluoromethylornithine (DFMO) and its derivatives. Polyamine contents are increased in many epithelial cancers, including breast cancer, melanoma, and prostate cancer. In order to image and measure the levels of ODC expression in malignant tumors, we have synthesized a derivative of ornithine, N5‐[18F]fluoroacetylornithine (N5‐[18F]FAO), for use in positron emission tomography. The precursor compound N2‐Boc‐N5‐bromoacetylornithine‐t‐butyl ester 2 was synthesized from 5‐amino‐2‐(tert‐butoxycarbonylamino)pentanoic acid, which was reacted with bromoacetyl chloride followed by esterification with tert‐butyl‐2,2,2‐trichloroacetamidate. Fluorination of the precursor produced a fluoro‐derivative, which was hydrolyzed in acid to obtain the desired compound, N5‐fluoroacetylornithine. The radiosynthesis of N5‐[18F]FAO was accomplished by radiofluorination of 2 with n‐Bu4N[18F], followed by high‐performance liquid chromatography (HPLC) purification and then by acid hydrolysis. The radiochemical yield was 6–10% (decay corrected) with an average of 8% (n=10) at the end of synthesis. The radiochemical purity was >99%, and specific activity was >1500 mCi/µmol. The synthesis time was 95–100 min from the end of bombardment. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
550.
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