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   3411695篇
  免费   284931篇
  国内免费   14046篇
耳鼻咽喉   48238篇
儿科学   106040篇
妇产科学   90967篇
基础医学   535432篇
口腔科学   95737篇
临床医学   298675篇
内科学   596222篇
皮肤病学   92862篇
神经病学   291215篇
特种医学   138219篇
外国民族医学   453篇
外科学   538318篇
综合类   106366篇
一般理论   2260篇
预防医学   275582篇
眼科学   78943篇
药学   240828篇
  18篇
中国医学   9922篇
肿瘤学   164375篇
  2021年   42905篇
  2020年   33799篇
  2019年   56856篇
  2018年   69150篇
  2017年   52736篇
  2016年   58249篇
  2015年   72560篇
  2014年   107085篇
  2013年   172500篇
  2012年   89718篇
  2011年   88860篇
  2010年   114977篇
  2009年   120318篇
  2008年   76730篇
  2007年   80370篇
  2006年   91177篇
  2005年   86508篇
  2004年   88751篇
  2003年   79991篇
  2002年   70147篇
  2001年   108589篇
  2000年   101302篇
  1999年   98917篇
  1998年   59421篇
  1997年   57293篇
  1996年   54734篇
  1995年   55513篇
  1994年   49863篇
  1993年   46543篇
  1992年   71307篇
  1991年   67914篇
  1990年   64810篇
  1989年   64121篇
  1988年   59951篇
  1987年   58645篇
  1986年   56135篇
  1985年   55795篇
  1984年   50172篇
  1983年   45344篇
  1982年   41863篇
  1981年   39336篇
  1980年   37160篇
  1979年   42583篇
  1978年   37010篇
  1977年   33818篇
  1976年   30574篇
  1975年   30321篇
  1974年   32129篇
  1973年   30844篇
  1972年   29378篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
American Indian and Alaska Native (AIAN) individuals are diverse culturally and geographically but share a high prevalence of chronic illness, largely because of obstacles to high-quality health care. The authors comprehensively examined cancer incidence and mortality among non-Hispanic AIAN individuals, compared with non-Hispanic White individuals for context, using population-based data from the National Cancer Institute, the Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries. Overall cancer rates among AIAN individuals were 2% higher than among White individuals for incidence (2014 through 2018, confined to Purchased/Referred Care Delivery Area counties to reduce racial misclassification) but 18% higher for mortality (2015 through 2019). However, disparities varied widely by cancer type and geographic region. For example, breast and prostate cancer mortality rates are 8% and 31% higher, respectively, in AIAN individuals than in White individuals despite lower incidence and the availability of early detection tests for these cancers. The burden among AIAN individuals is highest for infection-related cancers (liver, stomach, and cervix), for kidney cancer, and for colorectal cancer among indigenous Alaskans (91.3 vs. 35.5 cases per 100,000 for White Alaskans), who have the highest rates in the world. Steep increases for early onset colorectal cancer, from 18.8 cases per 100,000 Native Alaskans aged 20–49 years during 1998 through 2002 to 34.8 cases per 100,000 during 2014 through 2018, exacerbated this disparity. Death rates for infection-related cancers (liver, stomach, and cervix), as well as kidney cancer, were approximately two-fold higher among AIAN individuals compared with White individuals. These findings highlight the need for more effective strategies to reduce the prevalence of chronic oncogenic infections and improve access to high-quality cancer screening and treatment for AIAN individuals. Mitigating the disparate burden will require expanded financial support of tribal health care as well as increased collaboration and engagement with this marginalized population.  相似文献   
2.
3.
4.
AIDS and Behavior - Although misperceived norms often drive personal health behaviors, we do not know about this phenomenon in the context of antiretroviral therapy (ART) adherence. We conducted a...  相似文献   
5.
Spindler  L.  Alam  A.  Fathallah  N.  Rentien  A.-L.  Draullette  M.  Pommaret  E.  Thierry  M.-L.  Mituialy  A. El  Abbes  L.  Aubert  M.  Benfredj  P.  Far  E. Safa  Beaussier  H.  de Parades  V. 《Techniques in coloproctology》2022,26(2):143-146
Techniques in Coloproctology - The aim of our study was to assess the efficacy of sinus laser therapy (SiLaT) for the treatment of pilonidal disease. All adult patients treated with SiLaT in our...  相似文献   
6.
Clinical Rheumatology - This study aimed to assess treatment patterns and frequency of inadequate response associated with advanced therapy initiation among patients with ankylosing spondylitis...  相似文献   
7.

There are few published procedures for teaching athletic skills to children with autism spectrum disorder (ASD). This study used a multiple baseline across participants design to evaluate the effects of prompting, demand fading, and differential reinforcement, on the basketball shooting skills of four school-aged boys diagnosed with ASD. During baseline, all four boys rarely made correct and accurate baskets at the regulation height and distance for their age-group in youth basketball. Following intervention, all four boys increased their percentage of correct shots and accuracy, compared to baseline, and their shooting skills transferred to the game of “P-I-G” with peers.

  相似文献   
8.

Fears regarding various aspects tend to stimulate individuals to escape or to avoid the sources of the threat. We concluded that fears associated with the future aging process, like the fear of aging-related diseases, the fear of loneliness in old age, and the fear of death, would stimulate patterns of avoidance when it comes to ideal life expectancy. We expected fear of aging-related diseases and fear of loneliness in old age to be related to lower ideal life expectancies. We expected fear of death to be related to higher ideal life expectancies. In two adult lifespan samples [N1?=?1065 and N2?=?591; ages ranging from 18 to 95 years, M (SD)1?=?58.1 (17.2) years, M (SD)2?=?52.6 (18.1) years], we were able to support our hypothesis regarding fear of death. We furthermore found significant interactions among the fears, indicating that individuals fearing diseases or loneliness but being unafraid of death opted for the shortest lives. Our results indicate that fears regarding life in very old age might be associated with the wish to avoid this age period; the fear of death was however associated with the wish for particularly long lives, and thus, with distancing oneself from the dreaded event of death. We conclude that fears seem to be associated with how individuals approach old age and with what they wish for in their own future as aged people.

  相似文献   
9.
BackgroundReverse total shoulder arthroplasty (RSA) primarily varies between 2 implant design options: a 135 humeral stem inclination that closely resembles anatomic orientation, versus the Grammont-style 155 humeral stem inclination that further medializes and distalizes the center of rotation (COR). The purpose of this study was to compare deltoid force, glenoid strain, and simulated glenohumeral range of motion (ROM) between RSA 135 and RSA 155 designs, with a series of standardized permutations of glenosphere offset and rotator cuff pathology.MethodsTwelve fresh-frozen cadaveric shoulder specimens were studied using a shoulder simulator. Native shoulder motion profiles for reproducible abduction range of motion were established using a customized testing device. Optical 3-dimensional tracking and pressure sensors were used to accurately record glenohumeral range of motion (ROM), deltoid force, and glenoid strain for RSA 135 and RSA 155 designs. For each cohort, all combinations of glenosphere offsets and rotator cuff tendon involvement were evaluated.ResultsThere was no significant difference in the overall abduction ROM between the 155 and the 135 humeral stem implants (P = .75). Resting abduction angle and maximum abduction angle were significantly greater with a 155 + STD (standard offset) construct than with a 135 + STD construct (P < .001 and P = .01, respectively). Both stem inclinations decreased combined deltoid force requirements as compared the native shoulder with a massive cuff tear. Effective glenoid strain did not vary significantly between 135 + STD and 155 + STD constructs (P = .66).ConclusionOverall, range of motion between the 135 and the 155 humeral stem inclinations was not significantly different. The cumulative deltoid force was lower in RSA shoulders when compared to native shoulders with massive rotator cuff tears, highlighting the utility of both implant designs. The Grammont-style 155 stem coupled with a 2.5 mm inferior offset glenosphere required less deltoid force to reach maximum abduction than did the more anatomic, lateralized 135 stem coupled with a 4 mm lateral offset glenosphere.Level of EvidenceBasic Science, Biomechanics Controlled Laboratory Study  相似文献   
10.
In the last decade, the development of new radiopharmaceuticals for the imaging and therapy of prostate cancer has been a highly active and important area of research, especially focusing on the prostate-specific membrane antigen (PSMA), an antigen which is upregulated in prostate, as well as in other tumor cells. A large variety of PSMA ligands have been radiolabeled, to date. Among the various derivatives, PSMA-617 resulted to be one of the most interesting in terms of interaction with the antigen and clinical properties, and its lutetium-177 labeled version has recently been approved by regulatory agencies for therapeutic purposes. For this reasons, the radiolabeling with fluorine-18 of a PSMA-617 derivative might be of interest. Beside other methodologies to radiolabel macromolecules with fluorine-18, the “click-chemistry” approach resulted to be very useful, and the copper-catalyzed azide-alkyne cycloaddition (CuAAC) is considered one of most efficient and reliable. This paper proposes the synthesis of a suitable precursor for the radiolabeling with fluorine-18 of a new PSMA-617 derivative. The whole radiosynthetic procedure has been fully automated, and the final product, which proved to be stable in plasma, has been obtained with radiochemical yield and purity suitable for subsequent preclinical studies.  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