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   874篇
  免费   35篇
  国内免费   5篇
耳鼻咽喉   17篇
儿科学   26篇
妇产科学   13篇
基础医学   129篇
口腔科学   10篇
临床医学   71篇
内科学   251篇
皮肤病学   39篇
神经病学   87篇
特种医学   48篇
外科学   76篇
综合类   4篇
预防医学   23篇
眼科学   30篇
药学   50篇
中国医学   1篇
肿瘤学   39篇
  2023年   11篇
  2022年   7篇
  2021年   30篇
  2020年   14篇
  2019年   16篇
  2018年   19篇
  2017年   10篇
  2016年   18篇
  2015年   16篇
  2014年   20篇
  2013年   38篇
  2012年   59篇
  2011年   69篇
  2010年   35篇
  2009年   43篇
  2008年   59篇
  2007年   58篇
  2006年   35篇
  2005年   61篇
  2004年   45篇
  2003年   39篇
  2002年   38篇
  2001年   2篇
  2000年   7篇
  1999年   10篇
  1998年   12篇
  1997年   12篇
  1996年   8篇
  1995年   6篇
  1994年   8篇
  1993年   2篇
  1992年   21篇
  1991年   15篇
  1990年   7篇
  1989年   14篇
  1988年   6篇
  1987年   5篇
  1985年   5篇
  1984年   4篇
  1983年   3篇
  1982年   3篇
  1980年   4篇
  1976年   2篇
  1974年   3篇
  1973年   6篇
  1970年   1篇
  1969年   1篇
  1967年   1篇
  1966年   1篇
  1965年   1篇
排序方式: 共有914条查询结果,搜索用时 15 毫秒
71.
Obesity has reached epidemic proportions worldwide. Obesity results in reduced serum testosterone levels, which causes many disorders in men. Lifestyle modifications (increased physical activity and calorie restriction) can increase serum testosterone levels. However, it is unknown whether increased physical activity or calorie restriction during lifestyle modifications has a greater effects on serum testosterone levels. Forty-one overweight and obese men completed a 12-week lifestyle modification program (aerobic exercise training and calorie restriction). We measured serum testosterone levels, the number of steps, and the total energy intake. We divided participants into two groups based on the median change in the number of steps (high or low physical activities) or that in calorie restriction (high or low calorie restrictions). After the program, serum testosterone levels were significantly increased. Serum testosterone levels in the high physical activity group were significantly higher than those in the low activity group. This effect was not observed between the groups based on calorie restriction levels. We found a significant positive correlation between the changes in serum testosterone levels and the number of steps. Our results suggested that an increase in physical activity greatly affected the increased serum testosterone levels in overweight and obese men during lifestyle modification.  相似文献   
72.
Abstract:  In order to develop a diaphragm-type ventricular assist device (VAD), we studied the flow field change following structural modifications. We devised a center flow-type pump by putting a small projection on the center of the housing and/or diaphragm to provide a center in the flow field, and examined the following four types of VADs: N type without a projection, D type with a projection on the diaphragm, H type with a projection on the housing, and DH type with projections on both the diaphragm and housing. Computational fluid dynamics (CFD) was used for flow simulation. Particle image velocimetry (PIV) was also used to verify the reliability of the CFD method and to determine how the flow field changes in the presence of a projection. The results of the PIV and CFD analyses were comparable. The placement of a projection on the housing was most effective in rectifying the flow field.  相似文献   
73.
74.
75.
Discovery of the (pro)renin receptor uncovered a novel function of renin/prorenin as the receptor ligands in addition to the enzyme and its precursor. The bindings of renin and prorenin to the (pro)renin receptor trigger two major pathways: the angiotensin II–dependent pathway as a result of the enzymatic activation of renin/prorenin and the angiotensin II– independent intracellular pathway involving hypertrophic, hyperplastic, and profibrotic signals. A specific blocker of the receptor was discovered through identification of the amino acid sequence of prorenin prosegment that binds to the receptor and leads to non-proteolytic conversion of prorenin to its active form. A peptide containing this sequence was found to block the binding of prorenin to its receptor. Its infusion in animal models of diabetes and low-renin hypertension significantly inhibited the development and progression of nephropathy, but (pro)renin receptor blockade had no benefit in the clipped kidney of 2K1C rats or rat models of high-renin hypertension. Since renin is still active without a (pro)renin receptor, (pro)renin-receptor blockade elicits a maximum benefit under low-renin conditions. Thus, (pro)renin-receptor blockade can be a useful therapy for chronic kidney disease with low renin levels in the plasma.  相似文献   
76.
77.
Adnexal torsion is a relatively rare cause of lower abdominal pain in women, but in many cases it leads to a serious condition. We present a case of adnexal torsion of a mature cystic teratoma in which hemorrhagic infarction was reflected by progressive enlargement and wall thickening on successive plain abdominal radiographs. There has been no other report describing such changes of adnexal torsion on plain abdominal radiographs.  相似文献   
78.
79.
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by a selective loss of motor neurons in the motor cortex, brainstem, and spinal cord. It has been shown that oxidative stress plays a pivotal role in the progression of this motor neuron loss. We have previously reported that L-745,870, a dopamine D4 receptor antagonist, selectively inhibits oxidative stress-induced cell death in vitro and exerts a potent neuroprotective effect against ischemia-induced neural cell damage in gerbil. To investigate the efficacy of L-745,870 in the treatment of ALS, we here conducted a chronic administration of L-745,870 to transgenic mice expressing a mutated form of human superoxide dismutase gene (SOD1H46R); a mouse model of familial ALS, and assessed whether the mice benefit from this treatment. The pre-onset administration of L-745,870 significantly delayed the onset of motor deficits, slowed the disease progression, and extended a life span in transgenic mice. These animals showed a delayed loss of anterior horn cells in the spinal cord concomitant with a reduced level of microglial activation at a late symptomatic stage. Further, the post-onset administration of L-745,870 to the SOD1H46R transgenic mice remarkably slowed the disease progression and extended their life spans. Taken together, our findings in a rodent model of ALS may have implication that L-745,870 is a possible novel therapeutic means to the treatment of ALS.  相似文献   
80.
Neutrophil-specific antigen (NA) expression on neutrophils was analysed in 18 Japanese children before and after allogeneic stem cell transplantation (allo-SCT) with myeloablative regimen. Donor-recipient NA-incompatibility was present in one of eight NA1/NA2 heterozygous patients and eight of 10 NA1/NA1 or NA2/NA2 homozygous patients. After allo-SCTs from NA-incompatible donors, a neutrophil recipient-to-donor conversion was confirmed in all cases. Conversion to donor NA type was complete before the absolute neutrophil count reached 0.1 x 10(9)/l. These observations indicate that flow cytometric analysis of NA antigens is a simple and useful method for monitoring neutrophil engraftment in NA-incompatible allo-SCT.  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