首页 | 官方网站   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   36639篇
  免费   2829篇
  国内免费   156篇
医药卫生   39624篇
  2023年   209篇
  2022年   107篇
  2021年   693篇
  2020年   478篇
  2019年   702篇
  2018年   808篇
  2017年   620篇
  2016年   675篇
  2015年   816篇
  2014年   1158篇
  2013年   1625篇
  2012年   2420篇
  2011年   2707篇
  2010年   1502篇
  2009年   1385篇
  2008年   2293篇
  2007年   2595篇
  2006年   2459篇
  2005年   2545篇
  2004年   2294篇
  2003年   2188篇
  2002年   2018篇
  2001年   347篇
  2000年   265篇
  1999年   392篇
  1998年   451篇
  1997年   336篇
  1996年   280篇
  1995年   271篇
  1994年   240篇
  1993年   263篇
  1992年   236篇
  1991年   235篇
  1990年   188篇
  1989年   176篇
  1988年   177篇
  1987年   163篇
  1986年   127篇
  1985年   189篇
  1984年   260篇
  1983年   203篇
  1982年   242篇
  1981年   250篇
  1980年   245篇
  1979年   122篇
  1978年   145篇
  1977年   134篇
  1976年   118篇
  1974年   99篇
  1973年   85篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The Child and Adolescent Trial for Cardiovascular Health (CATCH) is a multisite intervention research study that builds on significant progress made in school health education research in the 1980s. The study has three phases: Phase I deals with study design, intervention, and measurement development, Phase II involves the main trial in 96 schools in four states, and Phase III focuses on analysis. The intervention program targets third-fifth grade students and focuses on multiple cardiovascular health behaviors, including eating habits, physical activity, and cigarette smoking. Classroom curricula, school environmental change, and family involvement programs are developed for each grade level and behavioral focus. This paper describes Phase II of CATCH with a rationale for cardiovascular health promotion with youth. The process of change that appears to be necessary for school-based health promotion and that will be tested in CATCH are presented as a framework to guide these efforts.  相似文献   
72.
A retrospective study of arthroscopic meniscal repair in 101 consecutive patients was conducted. Sixty-three patients constituted our study group. The arthroscopic technique used for meniscal repair was the inside-out method using malleable cannulas. Forty-five patients were available for clinical examination, with a mean follow-up of 27 months. Tegner and Lysholm scores were comparable to those previously reported for arthroscopic meniscal repair. The HSQ (similar to the SF-36) scores were equal to those from an age- and sex-matched normal population, indicating that individuals with repaired menisci do not have any residual negative effects on global health at mean 26.9 months' follow-up. The physical functioning subscale of the HSQ was found to be sensitive to patient perception of results. Complications included one case of restricted knee range of motion requiring arthroscopy and lysis of adhesions. Overall clinical results were 64% excellent, 27% good, and 9% failure. Age, sex, and length of the meniscal tear had no affect on clinical outcome.  相似文献   
73.
Seven total knee arthroplasty systems were tested to determine contact stress patterns and contact areas using a calibrated Fuji film stress analysis technique. Knees were loaded to 2,000 N (204 kg) at 15°, 60°, 90°, and 135° flexion at 24 and 37°C. Evaluation of stresses at 37°C at 15° and 60° using an average contact stress assessment technique indicated that the LCS meniscal bearing knee system, (DePuy, Warsaw, IN), the AMK knee with a constrained insert (DePuy), and the PFC knee with a posterior-lipped insert (Johnson and Johnson, Raynham, MA) had the lowest average contact stresses (near or below 10 MPa). The PFC with a regular insert (Johnson and Johnson), the Ortholoc II (Dow Corning Wright, Arlington, TN), and the AMK with a regular insert (DePuy) had intermediate contact stresses. The AMK with a Hylamer-M insert (DePuy) and the MG II (Zimmer, Warsaw, IN) had the highest average contact stresses (near or above 20 MPa). A stress-calibrated Fuji film measurement technique has shown that an assessment of ranges of contact stress provides much more information about regions of expected wear than an assessment of average contact stresses. Testing of the tibiofemoral articulation of artificial knees revealed that all knees had some areas of contact with maximum stresses in excess of 15 MPa. As the yield strength of ultrahigh-molecular-weight polyethylene is approximately 15 MPa, all tibial inserts could wear to some extent. Peak contact stresses at four test angles of the AMK, Series 7000 (Osteonics, Allendale, NJ:) Genesis (Smith & Nephew Orthopaedics, Memphis, TN), and MG II patellofemoral articulations were high (above 30 MPa). Contact areas varied from line-shaped to bilateral circular or elliptical shapes. The LCS knee system experienced substantially lower patellofemoral contact stresses and larger contact areas. Changes in conformity of knee designs are warranted to overcome wear problems. Peak contact stresses measured from the LCS meniscal bearing tibiofemoral and patellofemoral joint were in excess of 30 MPa in some areas at low flexion angles. This design does create large areas of contact at very low contact pressures, however, and for this reason is expected to wear less than other designs.  相似文献   
74.
75.
76.
Despite recent advances in understanding the immunopathogenesis of oral lichen planus (LP), the initial triggers of lesion formation and the essential pathogenic pathways are unknown. It is therefore not surprising that the clinical management of oral LP poses considerable difficulties to the dermatologist and the oral physician. A consensus meeting was held in France in March 2003 to discuss the most controversial aspects of oral LP. Part 1 of the meeting report focuses on (1) the relationship between oral LP and viral infection with special emphasis on hepatitis C virus (HCV), and (2) oral LP pathogenesis, in particular the immune mechanisms resulting in lymphocyte infiltration and keratinocyte apoptosis. Part 2 focuses on patient management and therapeutic approaches and includes discussion on malignant transformation of oral LP.  相似文献   
77.
78.
79.
Reductions in serum levels of Gc globulin, a hepatically synthesized component of the extracellular actin scavenger system responsible for complexing circulating actin and attenuating intravascular microthrombus formation, are associated with poor outcome in acute liver failure. Clinically applicable assays of the important actin-free fraction (Af-Gc) have not been available until now. We measured actin-free Gc globulin levels with a novel, rapid assay in 61 cases of acute liver failure (ALF) and in 91 patients with cirrhosis (40 of whom were clinically unstable with extrahepatic organ dysfunction), and studied associations with liver dysfunction, extrahepatic organ dysfunction, indices of disseminated coagulation, and outcome. Reductions in Af-Gc levels mirrored hepatic dysfunction and organ dysfunction in both groups, and discriminated patients with poor prognosis from those with good prognosis in the ALF cohort. Levels were lowest in patients with ALF (10% of control values), but levels were also markedly reduced in both unstable (28%) and stable (44%) patients with cirrhosis. Associations with markers of disseminated intravascular coagulation were seen in both groups, most notably in the cirrhosis cohort, supporting a pathophysiological role for reduced Af-Gc in the evolution of organ dysfunction. In acetaminophen-induced ALF, Af-Gc identified patients with poor prognosis as well as did the Acute Physiology and Chronic Health Evaluation (APACHE II) score (area under the receiver operating characteristic curve, 0.7), and in cirrhosis, Af-Gc was an independent predictor of mortality by multifactorial analysis. In conclusion, the importance of Af-Gc reductions in the development of multiple organ dysfunction in ALF and cirrhosis is highlighted, probably resulting from reduced hepatic production and peripheral exhaustion of this arm of the extracellular actin scavenger system.  相似文献   
80.
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-23

京公网安备 11010802026262号