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   2556篇
  免费   220篇
  国内免费   7篇
耳鼻咽喉   16篇
儿科学   96篇
妇产科学   45篇
基础医学   432篇
口腔科学   57篇
临床医学   208篇
内科学   531篇
皮肤病学   58篇
神经病学   241篇
特种医学   40篇
外国民族医学   2篇
外科学   352篇
综合类   28篇
一般理论   2篇
预防医学   214篇
眼科学   37篇
药学   115篇
中国医学   18篇
肿瘤学   291篇
  2022年   21篇
  2021年   49篇
  2020年   44篇
  2019年   43篇
  2018年   47篇
  2017年   44篇
  2016年   44篇
  2015年   46篇
  2014年   61篇
  2013年   92篇
  2012年   120篇
  2011年   139篇
  2010年   66篇
  2009年   76篇
  2008年   101篇
  2007年   150篇
  2006年   137篇
  2005年   123篇
  2004年   123篇
  2003年   111篇
  2002年   113篇
  2001年   65篇
  2000年   52篇
  1999年   58篇
  1998年   34篇
  1997年   28篇
  1996年   32篇
  1995年   32篇
  1994年   29篇
  1993年   18篇
  1992年   33篇
  1991年   33篇
  1990年   29篇
  1989年   39篇
  1988年   25篇
  1987年   45篇
  1986年   29篇
  1985年   26篇
  1984年   26篇
  1983年   21篇
  1982年   16篇
  1979年   26篇
  1978年   34篇
  1977年   31篇
  1976年   18篇
  1974年   16篇
  1973年   28篇
  1972年   22篇
  1971年   28篇
  1970年   20篇
排序方式: 共有2783条查询结果,搜索用时 15 毫秒
1.
We studied the parathyroid function in patients with advanced renal failure by determining their plasma concentrations of ionized calcium (iCa), intact parathyroid hormone (PTH) and its inactive metabolites (PTH-MM). The suppressibility of the parathyroidism was studied with a calcium infusion test. The intact PTH values of the nondialysis and dialysis patients did not statistically differ from each other. The concentrations of PTH-MM were, however, higher in the dialysis patients than in the nondialysis patients (p less than 0.05). The ratio of PTH-MM to intact PTH was lowest in healthy reference subjects and highest in dialysis patients (p less than 0.01), and did not correlate with the degree of intact PTH elevation in the patient groups. The calcium infusion test was carried out on 15 patients. All showed suppression in the elevated plasma intact PTH concentration and in 6 the intact PTH value normalized. The PTH-MM value did not normalize in any of the patients. During oral calcium treatment the degree of intact PTH suppression at an achieved concentration of plasma iCa was predictable from the infusion test. Three patients were parathyroidectomized after the calcium infusion test. In 2 of these elevated intact PTH normalized within 24 h while in 1 no change took place. In this latter case on clinical improvement was noted. We conclude that the determination of plasma intact PTH concentration especially of combined with plasma iCa value is a reliable means of studying the hyperparathyroidism associated with chronic renal failure.  相似文献   
2.
BACKGROUND: The use of suctioned fat grafts for correction of soft tissue defects is a widespread procedure in esthetic and reconstructive surgery. The main disadvantage of this simple and sensible procedure is the unpredictable absorption rate of the fat graft. A lot of research has been performed aiming for enhancement of the take of the fat grafts. OBJECTIVE: Our study was performed to find if there is any favorable donor site for fat harvesting. METHODS: This in vivo experiment using the nude mice model enables the study of the long-term survival of human fat in an animal model. The fat was harvested from three donor areas: the thigh, abdomen, and breast of a 48-year-old woman who came for an elective esthetic procedure. After centrifugation, 1 cc of fat was injected subcutaneously into the scalp of the nude mouse. There were 15 mice in each of the three groups, according to the selected donor sites. The animals were sacrificed 16 weeks after the procedure. The extracted fat was evaluated in terms of weight, volume, and six histologic parameters: integrity, vascularization, cyst formation, fibrosis, necrosis, and inflammation. RESULTS: This study could not find any statistically significant differences between the three investigated donor sites in the evaluated parameters. CONCLUSION: On the basis of this study, there is no favorable area for harvesting fat grafts. The donor site can be chosen according to the preference of the surgeon and the patient.  相似文献   
3.
Using liposomes radiolabelled by the 99mTechnetium-stannous chloride technique we have investigated the effect of surface charge on the stability of the isotope in vitro and in vivo. Dialysis of 99mTc-labelled positive, negative and neutral liposomes, which had been incubated in either saline or normal rat serum showed no significant loss of the isotope from the liposome surface with only 2 per cent of the isotope dialysed. A comparison of gel chromatography with dialysis confirmed that most of the isotope remained attached to the liposome surface, but it did reveal greater loss of the isotope, between 15 and 23 per cent. The liposome clearance rates obtained from 125I-egg phosphatidylcholine (EPC) and 99mTc dual-labelled positive or neutral liposomes were significantly different. The 99mTc marker was cleared five times faster from the positive liposomes and twice as fast from the neutral liposomes as the 125I-EPC integral membrane marker. The 99mTc attached to liposomes with a negative surface charge was stable in vivo and had the same clearance rate from the circulation as the 125I-EPC marker. These results indicate that the commonly used in vitro techniques for assessing liposome radiolabel stability are unsuitable for predicting the stability of the 99mTc in vivo.  相似文献   
4.
5.
A technique is described that provides adequate coverage for rib grafts used in reconstruction of the atrophic mandible. The flaps are highly vascular and thick because of the fibrous capsule that forms around the tissue expander. A one-stage expansion technique is used that reduces the total time needed for reconstruction.  相似文献   
6.
7.
8.

Background  

The aim of the current study is to investigate the relationship between physical anhedonia and psychopathological parameters, pharmacological parameters or motor side-effects in a sample of inpatients with schizophrenia in an acute episode of their illness.  相似文献   
9.
The diagnostic significance of anticytoplasmic autoantibodies (ANCA) was studied in 71 renal patients. The ANCA test was positive in 67% of patients with Wegener's granulomatosis (WG), in 35% of those with a simultaneous renal and respiratory tract disease but not diagnosed as WG and in 22% of patients with a renal disease associated with unspecific collagenosis/vasculitis. Among WG patients ANCA positivity clearly correlated with the presence of active renal disease. Interestingly, both ANCA-positive and -negative patients were encountered in the group with acute renal failure and acute extracapillary glomerulonephritis associated with diffuse pulmonary infiltrates. The diagnostic and clinical significance of the ANCA test in these cases remains for the present obscure. In the majority of the ANCA-positive renal patients with respiratory tract abnormalities, the antibodies showed diffuse cytoplasmic staining and were mostly of the IgG class, of both IgG and IgM classes in some cases and of IgG, IgM and IgA classes in 1 patient. In patients with unspecific vasculitis/collagenosis the level of ANCA was rather low, and the distribution of different isotypes resembled that of patients with respiratory symptoms. A certain isotype of ANCA or staining pattern did not mark out any clinicopathologic subgroup among the patients. Our findings indicate that the clinical picture of ANCA-positive patients varies considerably and the ANCA test may not be as specific a marker of WG as previously suggested.  相似文献   
10.
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