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   102246篇
  免费   7466篇
  国内免费   325篇
耳鼻咽喉   1355篇
儿科学   2594篇
妇产科学   2353篇
基础医学   12813篇
口腔科学   2101篇
临床医学   10036篇
内科学   22215篇
皮肤病学   1091篇
神经病学   8805篇
特种医学   3426篇
外国民族医学   3篇
外科学   16706篇
综合类   1455篇
现状与发展   1篇
一般理论   75篇
预防医学   8258篇
眼科学   2676篇
药学   6588篇
中国医学   142篇
肿瘤学   7344篇
  2023年   382篇
  2022年   574篇
  2021年   1696篇
  2020年   915篇
  2019年   1645篇
  2018年   1963篇
  2017年   1445篇
  2016年   1587篇
  2015年   1889篇
  2014年   2799篇
  2013年   4408篇
  2012年   6308篇
  2011年   6597篇
  2010年   3687篇
  2009年   3415篇
  2008年   6219篇
  2007年   6933篇
  2006年   6613篇
  2005年   6774篇
  2004年   6623篇
  2003年   6225篇
  2002年   6219篇
  2001年   876篇
  2000年   675篇
  1999年   860篇
  1998年   1300篇
  1997年   1166篇
  1996年   980篇
  1995年   992篇
  1994年   859篇
  1993年   767篇
  1992年   627篇
  1991年   567篇
  1990年   489篇
  1989年   520篇
  1988年   472篇
  1987年   501篇
  1986年   506篇
  1985年   558篇
  1984年   737篇
  1983年   782篇
  1982年   990篇
  1981年   932篇
  1980年   881篇
  1979年   484篇
  1978年   553篇
  1977年   602篇
  1976年   506篇
  1975年   451篇
  1973年   371篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
The purpose of this study was to assess 7 methods of fixation for a midtarsal osteotomy. Polyurethane foam models (N = 6) and cadaver specimens (N = 4-7) were used to examine the force generated by the different constructs of fixation. A midtarsal osteotomy was performed on each specimen in the test groups. The osteotomies were fixated either with 2 parallel 0.062-in Kirschner wires and 40-mm-long, 4-mm partially threaded, cancellous, cannulated titanium screws, an external ring fixator (frame), a frame with wires tensioned (tension), a frame with wires tensioned and compressed toward the osteotomy (tension and compression), a frame with tension, compression, and parallel Kirschner wires, or a frame with tension, compression, and two 4.0 cannulated parallel screws, respectively. Each model was fixated, and the force generated by the construct across the osteotomy was recorded via the use of pressure-sensitive film. Statistical analysis of the data in the polyurethane foam group determined that the use of frame with tension, compression, and two 4.0 parallel cannulated screws was statistically superior to 1) frame, 2) frame with tension, 3) 2 parallel Kirschner wires, 4) two 4.0 cannulated parallel screws, and 5) frame with tension and compression. A cadaver study determined that the frame with tension, compression, and 2 parallel Kirschner wires was statistically superior to 1) frame and 2) two parallel Kirschner wires. These findings suggest that there is a difference in the force generated by the type of fixation construct across a midtarsal osteotomy.  相似文献   
93.
OBJECTIVES: To determine the type of electrocardiogram (ECG) interpretation instruction in emergency medicine (EM) residency programs, the use and perceived value of teaching modalities and resources, and the methods used to assess competency of ECG interpretation. METHODS: An interactive survey instrument was posted on the Internet using SurveySuite, Inc., software and e-mailed to program directors (PDs) of all 125 Accreditation Council for Graduate Medical Education-approved U.S. EM residency programs. Responses are reported in total numbers and percentages. RESULTS: Ninety-nine of 125 PDs completed the online survey (response rate, 79.2%). Emergency department instruction (99%), case-based lectures (98%), and didactic lectures (98%) were most commonly used to teach interpretation of ECGs, followed by computer-based instruction (34%) and ECG laboratory (12%). The majority of programs (53%) spent more than eight hours on formal ECG lectures per year, while 11% spent less than three hours. Observation during clinical time (99%), lecture time (76%), and hypothetical cases (57%) were the most common ways to determine competency in reading ECGs, while clinical observation and hypothetical cases were perceived as the most valuable. The most commonly used resource was personal or departmental ECG files (91%), and this had the highest perceived value. The majority of PDs were comfortable with residents' abilities to read ECGs by the third year (96%) and fourth year (91%) of residency. CONCLUSIONS: These data suggest that EM PDs believe that EM residency is adequately preparing graduates to interpret ECGs. This goal is achieved through a variety of methods.  相似文献   
94.
95.
96.
Direct vascular injury after primary total knee arthroplasty is rare. This case report illustrates a 65-year-old female who was diagnosed with a pseudoaneurysm of the popliteal artery when she was investigated for increased leg swelling and pain 1 week after total knee arthroplasty. She had a percutaneous endovascular repair with a stent after thrombectomy.  相似文献   
97.
Pregnant and parenting adolescents living in inner cities are at risk for acquiring HIV through unprotected sexual activity. In addition to individual risk behaviors, a lack of socioeconomic and other environmental resources create risk environments that make certain communities vulnerable to both adolescent pregnancy and HIV/AIDS. Research indicates that adolescent parents, many who have histories of childhood trauma, may use their experience of young parenthood and the concomitant feelings of parental protectiveness as a source of renewed hope for their future. The purpose of this report is to explore the relationship between history of childhood abuse and high risk behaviors in adolescent Latino mothers and fathers enrolled in a randomized clinical trial of a culturally rooted, couple-focused HIV prevention program. In addition, this report describes the HIV prevention program that was designed specifically for young Latino parents wherein maternal and paternal protectiveness are viewed as intrinsic and developing critical factors that promote resiliency and motivate behavioral change.  相似文献   
98.
99.
BACKGROUND: Past receiver operating characteristic (ROC) studies have demonstrated that single photon emission computed tomography (SPECT) perfusion imaging by use of iterative reconstruction with combined compensation for attenuation, scatter, and detector response leads to higher area under the ROC curve (A(z)) values for detection of coronary artery disease (CAD) in comparison to the use of filtered backprojection (FBP) with no compensations. A new ROC study was conducted to investigate whether this improvement still holds for iterative reconstruction when observers have available all of the imaging information normally presented to clinical interpreters when reading FBP SPECT perfusion slices. METHODS AND RESULTS: A total of 87 patient studies including 50 patients referred for angiography and 37 patients with a lower than 5% likelihood for CAD were included in the ROC study. The images from the two methods were read by 4 cardiology fellows and 3 attending nuclear cardiologists. Presented for the FBP readings were the short-axis, horizontal long-axis, and vertical long-axis slices for both the stress and rest images; cine images of both the stress and rest projection data; cine images of selected cardiac-gated slices; the CEQUAL-generated stress and rest polar maps; and an indication of patient gender. This was compared with reading solely the iterative reconstructed stress slices with combined compensation for attenuation, scatter, and resolution. With A(z) as the criterion, a 2-way analysis of variance showed a significant improvement in detection accuracy for CAD for the 7 observers (P = .018) for iterative reconstruction with combined compensation (A(z) of 0.895 +/- 0.016) over FBP even with the additional imaging information provided to the observers when scoring the FBP slices (A(z) of 0.869 +/- 0.030). When the groups of 3 attending physicians or 4 cardiology fellows were compared separately, the iterative technique was not statistically significantly better; however, the A(z) for each of the 7 observers individually was larger for iterative reconstruction than for FBP. Compared with results from our previous studies, the additional imaging information did increase the diagnostic accuracy of FBP for CAD but not enough to undo the statistically significantly higher diagnostic accuracy of iterative reconstruction with combined compensation. CONCLUSIONS: We have determined through an ROC investigation that included two classes of observers (experienced attending physicians and cardiology fellows in training) that iterative reconstruction with combined compensation provides statistically significantly better detection accuracy (larger A(z)) for CAD than FBP reconstructions even when the FBP studies were read with all of the extra clinical nuclear imaging information normally available.  相似文献   
100.
Intractable tinnitus can lead to serious consequences. Study evidence indicates that the central nervous system is involved in generation and maintenance of chronic tinnitus and that tinnitus and other neurologic symptoms such as chronic pain may share similar mechanisms. Brain ablation and stimulation are used to treat chronic pain with success. Recent studies showed that ablation and stimulation in non-auditory areas resulted in tinnitus improvement. Deep brain stimulation (DBS) may be an alternative treatment for intractable tinnitus and deserves further study.  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