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   49014篇
  免费   4093篇
  国内免费   144篇
耳鼻咽喉   462篇
儿科学   1580篇
妇产科学   990篇
基础医学   6838篇
口腔科学   589篇
临床医学   5856篇
内科学   10498篇
皮肤病学   1068篇
神经病学   4846篇
特种医学   1571篇
外国民族医学   1篇
外科学   7084篇
综合类   279篇
一般理论   41篇
预防医学   3962篇
眼科学   914篇
药学   3015篇
中国医学   123篇
肿瘤学   3534篇
  2023年   204篇
  2022年   300篇
  2021年   796篇
  2020年   626篇
  2019年   1134篇
  2018年   1422篇
  2017年   1131篇
  2016年   1143篇
  2015年   1426篇
  2014年   1681篇
  2013年   2380篇
  2012年   3364篇
  2011年   3610篇
  2010年   2014篇
  2009年   1797篇
  2008年   3142篇
  2007年   3327篇
  2006年   3210篇
  2005年   3294篇
  2004年   3218篇
  2003年   3122篇
  2002年   3104篇
  2001年   460篇
  2000年   370篇
  1999年   426篇
  1998年   460篇
  1997年   437篇
  1996年   352篇
  1995年   393篇
  1994年   313篇
  1993年   309篇
  1992年   240篇
  1991年   261篇
  1990年   228篇
  1989年   197篇
  1988年   198篇
  1987年   201篇
  1986年   203篇
  1985年   175篇
  1984年   204篇
  1983年   159篇
  1982年   213篇
  1981年   201篇
  1980年   185篇
  1979年   151篇
  1978年   137篇
  1977年   126篇
  1976年   105篇
  1974年   93篇
  1973年   92篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
The expression of MHC isoforms in the skeletal muscles of nine patients with Duchenne muscular dystrophy (DMD) (from 2.5 to 15 yr of age) and three DMD carriers was studied using different specific anti-MHC MAbs. We also analyzed muscle fiber size and fiber reactivity with acridine orange and/or with a surface antigen marker. One-quarter of all fibers of DMD patients, or less with age, were of normal size and contained only adult slow MHC. Half of the muscle fibers contained adult and developmental MHCs. Only half of these fibers were representative of an active regenerative process. MHC co-expression also altered the proportion of normal fast or slow fibers. Adult fast MHCs were expressed as unique MHC only in small and very small fibers in the oldest DMD patients. In DMD carrier muscles, the greatest alterations in MHC expression were observed in patients with the most reduced dystrophin expression. However, MHC changes in dystrophin-positive fibers were similar to those observed in dystrophin-free fibers. In conclusion, disruptions or delays in the switching of all genes coding for adult fast and slow MHC and developmental MHC coincided with dystrophin deletion and with perturbations in its expression.  相似文献   
52.
We report our initial experience with aortic valve replacement using robotic assistance. All procedures were performed with peripheral cardiopulmonary bypass, transthoracic aortic cross-clamp, and antegrade cold crystalloid cardioplegia. One or two ports and a 5-cm intercostal incision in the right chest were used for access. All patients had aortic valve replacement performed robotically. Between February and September 2004, five patients underwent robotic aortic valve replacement. The mean age was 59 years (range 35-82 years). There were no incisional conversions, death, stokes, or reoperations for bleeding. Overall mean study times were as follows: procedure, 231.2 min (range 180-315 min); cardiopulmonary bypass, 121.5 min (range 83-173 min), and cross-clamp, 98.2 min (range 67-140 min). One patient developed postoperative pneumonia. Aortic valve replacement can be successfully performed with the da Vinci robotic system.  相似文献   
53.
Kollicoat IR, a new pharmaceutical excipient developed as a coating polymer for instant release tablets, was evaluated as a carrier in solid dispersions of Itraconazole. The solid dispersions were prepared by hot stage extrusion. Modulated temperature differential scanning calorimetry and X-ray powder diffraction were used to evaluate the miscibility of the drug and the carrier. The pharmaceutical performance was evaluated by dissolution experiments, performed in simulated gastric fluid without pepsin (SGF(sp)). In the X-ray diffractograms no Itraconazole peaks were visible; the polymer on the other hand appeared to be semi-crystalline. Moreover, its crystallinity increased during the extrusion process due to exposure to heat and shear forces. Modulated temperature differential scanning calorimetry analysis showed that the drug and the polymer formed a two phase system. Separate clusters of glassy Itraconazole were present for drug loads of 40% or higher, indicating further phase separation. Dissolution measurements demonstrated a significantly increased dissolution rate for the solid dispersions compared to physical mixtures. Interestingly the physical mixture made up of glassy Itraconazole and Kollicoat IR (20/80, w/w) showed a dissolution rate and maximum that was much higher than that of the physical mixture made up of crystalline Itraconazole and that of pure glassy Itraconazole. The results of this study show that Kollicoat IR is a promising excipient for the formulation of solid dispersions of Itraconazole prepared by hot stage extrusion.  相似文献   
54.
Alcohol and other drug (AOD) use behaviors of health professions students (HPS) were assessed by surveying both university-based HPS and other nursing programs in a Midwestern state in 1999. Response was 2,646 (56.4%) of surveyed students. Family history of alcohol-related and drug-related problems were reported by 39.8% and 13.9%, respectively, with 42.6% of respondents reporting one or both. Among nursing respondents, 48.1%, 19.2% and 51.1%, respectively, reported family problems with alcohol, drugs, or one or both. Past-year alcohol use was comparable to undergraduate college students (UCS) nationally (83%); heavy drinking, tobacco and recreational drug use by HPS were lower. Past year drug use was highest among medical students. Marijuana was the predominant illicit drug; medical students and males most often reported use. Health professions educational systems should proactively address student AOD prevention, education and assistance needs.  相似文献   
55.
56.
This paper describes a quick procedure for cadaveric liver graft retrieval during multiple organ harvesting. The technique is based on minimal preliminary dissection, absence of in situ direct portal perfusion, and en bloc removal of the liver and pancreas, with an aortic patch encompassing the coeliac trunk and superior mesenteric artery. The results of 110 pediatric liver transplantations with 109 organs harvested using this technique are reported. There were no graft harvesting injuries. The liver graft primary nonfunction rate was 4.5% (5/110). The 3-month retransplantation rate was 10%. The actual patient survival rates were 93% at 3 months and 90% at 1 year; actual graft survival rates were 85.5% and 78%, respectively. The technique described was at least as safe as conventional procedures. A major advantage of the procedure is its flexibility, which allows for the easily combined procurement of other organs (whole pancreas and intestine).  相似文献   
57.
58.
59.
60.
Neurotropic melanoma has generally been described in the context of desmoplastic melanoma. The vast majority of melanomas displaying neurotropism contain relatively little or no melanin. Herein, we report an unusual case of neurotropic melanoma with prominent melanin content. The patient developed a tumor notable For pagetoid (superficial spreading) melanoma with partial regression and a deep component characterized by perineurial aggregates of melanophages and intraneural infiltration by melanoma cells. This case serves to alert dermatopathologists to the fact that the spectrum of neurotropic melanoma includes tumors with perineurial aggregates of pigment-containing cells.  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