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   10801篇
  免费   560篇
  国内免费   55篇
耳鼻咽喉   145篇
儿科学   179篇
妇产科学   113篇
基础医学   1500篇
口腔科学   234篇
临床医学   640篇
内科学   2653篇
皮肤病学   208篇
神经病学   797篇
特种医学   354篇
外科学   1813篇
综合类   58篇
一般理论   3篇
预防医学   314篇
眼科学   195篇
药学   691篇
中国医学   35篇
肿瘤学   1484篇
  2023年   85篇
  2022年   148篇
  2021年   294篇
  2020年   169篇
  2019年   250篇
  2018年   306篇
  2017年   192篇
  2016年   226篇
  2015年   238篇
  2014年   318篇
  2013年   380篇
  2012年   633篇
  2011年   708篇
  2010年   382篇
  2009年   313篇
  2008年   532篇
  2007年   608篇
  2006年   601篇
  2005年   574篇
  2004年   497篇
  2003年   473篇
  2002年   430篇
  2001年   269篇
  2000年   232篇
  1999年   224篇
  1998年   114篇
  1997年   97篇
  1996年   80篇
  1995年   63篇
  1994年   76篇
  1993年   80篇
  1992年   181篇
  1991年   169篇
  1990年   158篇
  1989年   163篇
  1988年   124篇
  1987年   146篇
  1986年   101篇
  1985年   90篇
  1984年   80篇
  1983年   78篇
  1982年   37篇
  1981年   35篇
  1979年   59篇
  1978年   46篇
  1977年   39篇
  1975年   29篇
  1973年   28篇
  1971年   28篇
  1970年   33篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
miRNA‐221 (miR‐221) is known to be abnormally expressed in many human cancers. The serum levels of miR‐221 have been reported as a tumor marker for malignant melanoma (MM). We hypothesized that the hair shaft miR‐221 levels may be increased in patients with MM. We therefore assessed the possibility that hair shaft miR‐221 levels could be a marker for MM. The hair shaft miR‐221 levels were significantly higher in patients with MM than controls. The rates of increased hair shaft miR‐221 levels above the cut‐off value were comparable to those of serum 5‐S‐CD, which is a tumor marker commonly used for MM. Measurements of the hair shaft miR‐221 levels could have potential clinical value in the detection of MM. This is the first report investigating the hair shaft levels of an miRNA in patients with MM. Our investigations offer new insight into the relationship between miR‐221 and MM, and may provide a new, non‐invasive way to screen for melanoma.  相似文献   
3.
4.
The neonatal mortality rate has so far been used as the most reasonable risk indicator of pregnancy outcomes in a community. This rate, however, has decreased considerably, and a new indicator is required. The proportions of pre-term infants, infants with foetal growth retardation and high-risk infants were defined on the basis of both weight and gestational age at birth. Using these as pregnancy outcome indicators, perinatal risk factors in a rural community were examined. The study results agreed with the general knowledge on perinatal risk factors. This method can be used as an alternative to the conventional method for assessing the maternal and child health in a community.  相似文献   
5.
Recently, food intake in Japan has been characterized by an increase in fat intake, especially animal-fat intake and the maintenance of excess salt (sodium chloride) intake. It is generally accepted that the increase in fat intake is closely related to atherosclerosis, and excess salt intake is a high risk factor for the development of hypertension and cerebrovascular lesions. So far, in almost all reports, the increase in fat intake and excess salt intake have been studied independently, and there have been few reports on the combined effects of these two factors. Taking the above things into consideration, it would seem to be very interesting to investigate the effect of excess salt intake on lipid metabolism. In this paper, we studied the effects of excess salt intake on lipoprotein and apolipoprotein metabolisms, using stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Kyo: Wistar rats (WKY) as model animals. The results obtained were as follows: A significant increase in the concentration of serum total cholesterol (TC) was observed in SHRSP and WKY, when the rats were given a regular diet (CE-2, Clea Japan Inc.) and 1% sodium chloride solution (1% NaCl) as drinking water for 4 weeks. This was accompanied by a tendency toward increases in the concentrations of serum apolipoproteins in both strains. These results suggest that excess salt intake could accelerate the production of serum total lipoproteins in SHRSP and WKY, when the rats are fed a regular diet. Next, 1% NaCl and a high-fat and high-cholesterol diet (HFC diet) were simultaneously given to SHRSP and WKY for 6 weeks. The effects of simultaneous administration on lipoprotein and apolipoprotein metabolisms were compared with those of HFC feeding. One percent NaCl did not markedly affect hypercholesterolemia in WKY, while it induced more marked hypercholesterolemia in SHRSP that was associated with extreme elevations of serum TC and the atherogenic index (A.I.). This deleterious effect of 1% NaCl in SHRSP was due to drastic elevations of cholesterol contents in the very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) fractions. This was also associated with marked increases in apo B contents in the VLDL, IDL and LDL fractions and significant increases in apo E contents in the VLDL and IDL fractions. These results indicate that 1% NaCl induced much larger increases in serum atherogenic beta-lipoproteins in SHRSP.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
6.
7.
8.
9.
10.
We have found that steroid bolus withdrawal prior to graft reperfusion increased the incidence of acute cellular rejection (ACR). This study aims to clarify how initial steroid bolus (ISB) injection at reperfusion influences the kinetics of CD8(+) alloreactive immune responses immediately after living donor liver transplantation (LDLT). A total of 49 hepatitis C virus (HCV)-infected recipients were classified into 3 groups according to hierarchical clustering by preoperative CD8(+)CD45 isoforms. The naive T cell proportion was considerably higher in Group I than in Groups II and III, whereas Group II recipients had the highest effector memory (EM) T cells and Group III the highest effector T cells. The frequency of ACR was significantly higher in recipients without ISB than in those with ISB. In particular, the ACR rates were the highest in Group II without ISB. Following ISB, the proportion of effector T cells was promptly upregulated within 6 hours after graft reperfusion, simultaneously with the upregulation of CD27(-)CD28(-) subsets, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha and perforin expression, which significantly correlated with increasing interleukin (IL)-12 receptor beta 1 cells. These were then downregulated to below preoperative levels by tacrolimus (Tac) administered at 24 hours. These changes did not occur in the absence of ISB. In Group II without ISB, the downregulation of IL-12Rbeta1(+) cells was the greatest, consistent with the highest rates of ACR and mortality (60%). In conclusion, ISB must be done in place, especially in Group II with preexisting high EM T cells, to enable the development of early allograft acceptance.  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