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   1515篇
  免费   84篇
  国内免费   12篇
儿科学   40篇
妇产科学   55篇
基础医学   99篇
口腔科学   25篇
临床医学   99篇
内科学   173篇
皮肤病学   14篇
神经病学   128篇
特种医学   56篇
外科学   77篇
综合类   62篇
一般理论   1篇
预防医学   561篇
眼科学   14篇
药学   66篇
中国医学   2篇
肿瘤学   139篇
  2024年   2篇
  2023年   69篇
  2022年   88篇
  2021年   73篇
  2020年   120篇
  2019年   79篇
  2018年   60篇
  2017年   101篇
  2016年   66篇
  2015年   69篇
  2014年   123篇
  2013年   104篇
  2012年   52篇
  2011年   33篇
  2010年   76篇
  2009年   59篇
  2008年   45篇
  2007年   24篇
  2006年   34篇
  2005年   18篇
  2004年   23篇
  2003年   28篇
  2002年   23篇
  2001年   18篇
  2000年   24篇
  1999年   18篇
  1998年   10篇
  1997年   11篇
  1996年   11篇
  1995年   12篇
  1994年   14篇
  1993年   11篇
  1992年   19篇
  1991年   15篇
  1990年   11篇
  1989年   14篇
  1988年   7篇
  1987年   6篇
  1986年   8篇
  1985年   3篇
  1984年   2篇
  1983年   4篇
  1982年   4篇
  1981年   5篇
  1980年   3篇
  1978年   3篇
  1966年   2篇
  1965年   2篇
  1949年   1篇
  1947年   1篇
排序方式: 共有1611条查询结果,搜索用时 9 毫秒
61.
62.
《The Journal of infection》2020,80(3):255-260
IntroductionStreptococcus agalactiae (group B streptococci; GBS) is an uncommon cause of bacterial meningitis in adults.MethodsWe reviewed literature published between 1975 and 2018. Studies were included if they reported age, sex and outcome of patients above 16 years of age with cerebrospinal fluid culture (CSF) positive for GBS.ResultsSixty-seven articles describing 141 patients were included. Median age was 56 years (IQR 41–66); 52% were male. Fifty-three patients (38%) were immunocompromised and CSF leakage was reported in 9 (10%) of 88 immunocompetent patients. Sixty-two patients (44%) had extra-meningeal foci of infection, most commonly endocarditis, which occurred in 14 patients (12%). Twenty-eight patients (23%) were described as previously healthy. Forty-four (31%) of the 141 patients died, after a median duration of 5 days after admission. Death was associated with advanced age and an immunocompromised state.ConclusionGBS meningitis in adults mainly occurs in those with underlying conditions such as immunocompromised state, CSF leakage, and endocarditis. These conditions should be actively sought for in adults with GBS meningitis.  相似文献   
63.
BackgroundBetter midsole materials and comfort have been incorporated into more expensive shoes and are popular with runners. Consequently, knockoff running shoes are currently widely distributed in the Chinese market and and cost only 30%–50% of the total price of genuine branded products.Research questionUncertainty exists concerning the beneficial effects of advanced shoe material application in decreasing foot loading or impact force during running. Additionally, using comfort as a criterion to identify genuine branded running shoes may exclude brand factor.MethodsFifteen healthy male volunteers were asked to perform two different tests, including running and a comfort evaluation. Each participant was asked to identify which footwear was the Adidas brand shoe based on their perception of comfort.ResultsTime to the first peak of the vertical ground reaction force occurred significantly later when subjects wore the genuine branded shoe compared to knockoff shoe 1 (p = 0.003) and knockoff shoe 2 (p = 0.015) footwea. The genuine branded shoe (p = 0.005) and knockoff shoe 1 (p = 0.029) were significantly more comfortable compared to the knockoff shoe 2. Only four subjects selected the genuine branded shoe, whereas six subjects selected both the genuine branded shoe and knockoff shoe 1.SignificanceKnockoff running footwear significantly increases impact loading compared to the genuine branded product, thereby posing greater risk of running injury.  相似文献   
64.
65.
This research presents a methodology for optimal design of the needle geometry to minimize the insertion force and bevel length based on mathematical models of cutting edge inclination and rake angles and the insertion force. In brachytherapy, the needle with lower insertion force typically is easier for guidance and has less deflection. In this study, the needle with lancet point (denoted as lancet needle) is applied to demonstrate the model-based optimization for needle design. Mathematical models to calculate the bevel length and inclination and rake angles for lancet needle are presented. A needle insertion force model is developed to predict the insertion force for lancet needle. The genetic algorithm is utilized to optimize the needle geometry for two cases. One is to minimize the needle insertion force. Using the geometry of a commercial lancet needle as the baseline, the optimized needle has 11% lower insertion force with the same bevel length. The other case is to minimize the bevel length under the same needle insertion force. The optimized design can reduce the bevel length by 46%. Both optimized needle designs were validated experimentally in ex vivo porcine liver needle insertion tests and demonstrated the methodology of the model-based optimal needle design.  相似文献   
66.
67.
68.
69.
Zumel-Marne  Angela  Kundi  Michael  Castaño-Vinyals  Gemma  Alguacil  Juan  Petridou  Eleni Th  Georgakis  Marios K.  Morales-Suárez-Varela  Maria  Sadetzki  Siegal  Piro  Sara  Nagrani  Rajini  Filippini  Graziella  Hutter  Hans-Peter  Dikshit  Rajesh  Woehrer  Adelheid  Maule  Milena  Weinmann  Tobias  Krewski  Daniel  ′t Mannetje  Andrea  Momoli  Franco  Lacour  Brigitte  Mattioli  Stefano  Spinelli  John J.  Ritvo  Paul  Remen  Thomas  Kojimahara  Noriko  Eng  Amanda  Thurston  Angela  Lim  Hyungryul  Ha  Mina  Yamaguchi  Naohito  Mohipp  Charmaine  Bouka  Evdoxia  Eastman  Chelsea  Vermeulen  Roel  Kromhout  Hans  Cardis  Elisabeth 《Journal of neuro-oncology》2020,147(2):427-440
Journal of Neuro-Oncology - We used data from MOBI-Kids, a 14-country international collaborative case–control study of brain tumors (BTs), to study clinical characteristics of the tumors in...  相似文献   
70.
BackgroundWhile sleeve gastrectomy (SG) has lower perioperative risk compared with Roux-en-Y gastric bypass (RYGB), long-term data about their differential impact on overall health are unclear. Hospital use after bariatric surgery is an important parameter for improving peri- and postoperative care.ObjectiveThis present study was aimed to compare SG and RYGB in terms of their effect on long-term hospital-based healthcare utilization.SettingMulticenter, statewide database.MethodsA retrospective cohort study of adult patients who underwent SG and RYGB between 2009 and 2011, with follow-up until 2015 and 2-year presurgery information. Propensity score–matched SG and RYGB groups were created using preoperative demographic characteristics, co-morbidities, and presurgery hospital use, measured by cumulative length of stay (LOS) and frequency of emergency department visits. Postsurgery yearly LOS, incidence of hospital visits, and the reason for the visit were compared. Primary outcomes included postoperative hospital visits during years 1 to 4 after bariatric surgery and cumulative LOS. Secondary outcomes included specific reasons for hospital use.ResultsThere were 3540 SG and 13,587 RYGB patients, whose mean (95% confidence interval [CI]) LOS was 1.3 (1.3–1.4), .9 (.8–1), 1 (.9–1.1), and 1.2 (1–1.3) days at years 1 through 4, respectively. Postoperative yearly LOS was similar between the 2 propensity-matched groups. The risk of hospitalizations (odd ratio .73, 95% CI .64–.84, P < .0001) and emergency department visits (odds ratio .84, 95% CI .75–.95, P = .005) was significantly lower for SG, during the first postoperative year. The reverse was seen at the fourth postoperative year, with higher risk of emergency department use after SG (odds ratio 1.16, 95% CI 1.01–1.33, P = .035).ConclusionPostoperative 4-year hospital utilization remains low for both SG and RYGB. The previously established lower early perioperative risk of SG was not appreciated for longer-term hospital use compared with RYGB.  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