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   1603篇
  免费   94篇
  国内免费   79篇
耳鼻咽喉   14篇
儿科学   71篇
妇产科学   21篇
基础医学   186篇
口腔科学   19篇
临床医学   219篇
内科学   306篇
皮肤病学   53篇
神经病学   98篇
特种医学   302篇
外科学   145篇
综合类   44篇
一般理论   7篇
预防医学   109篇
眼科学   12篇
药学   104篇
中国医学   7篇
肿瘤学   59篇
  2021年   7篇
  2020年   6篇
  2019年   9篇
  2018年   15篇
  2017年   12篇
  2016年   23篇
  2015年   15篇
  2014年   30篇
  2013年   38篇
  2012年   47篇
  2011年   36篇
  2010年   43篇
  2009年   48篇
  2008年   51篇
  2007年   103篇
  2006年   42篇
  2005年   46篇
  2004年   30篇
  2003年   57篇
  2002年   57篇
  2001年   35篇
  2000年   47篇
  1999年   49篇
  1998年   79篇
  1997年   81篇
  1996年   61篇
  1995年   69篇
  1994年   43篇
  1993年   41篇
  1992年   34篇
  1991年   39篇
  1990年   31篇
  1989年   51篇
  1988年   41篇
  1987年   32篇
  1986年   30篇
  1985年   55篇
  1984年   23篇
  1983年   24篇
  1982年   27篇
  1981年   20篇
  1980年   27篇
  1979年   10篇
  1978年   9篇
  1977年   22篇
  1976年   20篇
  1975年   11篇
  1974年   7篇
  1973年   7篇
  1970年   4篇
排序方式: 共有1776条查询结果,搜索用时 34 毫秒
1.
The purpose of this study is to determine the role of liver biopsy and outcome of patients undergoing donor evaluation for adult-to-adult right hepatic lobe living donor liver transplantation (LDLT). Records of patients presenting for a comprehensive donor evaluation between 1997 and February 2005 were reviewed. Liver biopsy was performed only in patients with risk factors for abnormal histology. Two hundred and sixty patients underwent a comprehensive donor evaluation and 116 of 260 (45%) were suitable for donation, 14 of 260 (5.4%) did not complete evaluation and 130 of 260 (50%) were rejected. Four patients underwent unsuccessful hepatectomy surgery due to discovery of intraoperative abnormalities. Between 1997 and 2001, the acceptance rate of donor candidates (63%) was higher than 2002-2005 (36%), p < 0.0001. Sixty-six of the 150 eligible patients (44%) fulfilled criteria for liver biopsy and 28 of 66 (42%) had an abnormal finding. Less than half of the patients undergoing donor evaluation were suitable donors and the donor acceptance rate has declined over time. A large proportion of the patients undergoing liver biopsy have abnormal findings. Our evaluation process failed to identify 4 of 103 who had aborted donor surgeries.  相似文献   
2.
3.
Coronary artery bypass grafts: visualization with MR imaging   总被引:1,自引:0,他引:1  
Gomes  AS; Lois  JF; Drinkwater  DC  Jr; Corday  SR 《Radiology》1987,162(1):175
  相似文献   
4.
Anticoagulant drugs are known to have an effect on tumour growth. However, the mechanisms by which they act are poorly understood, and have therefore been investigated in this study. Wistar rats were given eight weekly subcutaneous injections of azoxymethane, at a dose of 10 mg kg-1 week-1. Following this they were randomized into two groups: a control group, which received no further treatment, and a warfarin treated group, which received warfarin at 'non-therapeutic' doses in their drinking water, for a further 8 weeks. Pairs of rats from each group were killed at 5-weekly intervals from 10 to 35 weeks after the first azoxymethane injection. At 40 weeks all remaining rats were killed. Samples of colonic mucosa from the descending colon and rectum were taken for scanning electron microscopy. The number of microadenomas per low power field was determined in both groups at each time interval. Tumour incidence and distribution were noted in animals killed at 40 weeks. The median number of microadenomas was significantly lower in warfarin treated animals than in controls at all time intervals. Tumour number was also significantly decreased by warfarin treatment (27 in azoxymethane treated animals, 10 in animals receiving azoxymethane and warfarin, P less than 0.05). The distribution of tumours along the colon was similar to that seen previously, following 12 weeks of azoxymethane. These effects occurred despite the non-concurrent administration of azoxymethane and warfarin.  相似文献   
5.
6.
Replication-defective retroviruses expressing the t- neu oncogene, or a hybrid protein with the neu tyrosine kinase linked to the external region of the human epidermal growth factor receptor ( egfr-neu ), were used to establish lines of murine oligodendroglial precursor cells. Differentiation of the t- neu lines into myelin-associated glycoprotein (MAG)-positive oligodendrocytes was induced by dibutyryl cAMP, and the egfr-neu line showed limited differentiation in vitro upon withdrawal of epidermal growth factor. Cerebellar granule cell neurons expressed mitogens for the cell lines. Upon transplantation into demyelinated lesions, t- neu line cells engaged with the demyelinated axons whereas the egfr-neu line cells differentiated further and ensheathed the axons. These cell lines thus interact with neurons in vitro and in vivo and can be used as tools to define the molecules involved in different stages of neuron-glia interaction.  相似文献   
7.
Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (Vm) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (Gmax = +dV/dtmax). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, Gmax was of a similar magnitude (551 ±30 and 555 ± 44 cm/s2, respectively) despite major differences in the respective D, Vm, Q and R values. In neither artery was there a relationship between Gmax and either resting Q or R. At the brachial artery level, Gmax was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between Gmax and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow.  相似文献   
8.
In a prospective, randomized, double-blind study, 49 patients underwent lumbar myelography using iotrol (24 patients) or metrizamide (25 patients). The diagnostic imaging adequacy of iotrol was comparable with that of metrizamide. After iotrol myelography, adverse reactions were fewer, less severe, and of shorter duration than were those following metrizamide myelography. Thirteen of 24 patients (54%) receiving iotrol reported some adverse reactions compared with 24 of 25 patients (96%) receiving metrizamide. Five moderate and one severe adverse reaction occurred in the group receiving iotrol. Fourteen moderate and eight severe adverse reactions occurred in the group receiving metrizamide. Thirty-eight patients underwent electroencephalography both before and after myelography (19 iotrol and 19 metrizamide). None of the EEGs obtained after iotrol myelography changed from baseline, while seven of the EEGs obtained after metrizamide myelography showed changes from baseline. Iotrol was judged superior to metrizamide as a contrast medium in this patient population.  相似文献   
9.
10.
Renz  JF; Kalf  GF 《Blood》1991,78(4):938-944
Chronic exposure of humans to benzene (BZ), a myelotoxin, causes aplastic anemia and acute leukemia. The stromal macrophage that produces interleukin-1 (IL-1), a cytokine essential for hematopoiesis, is a target of BZ's toxicity. Monocyte dysfunction and decreased IL-1 production have been shown to be involved in aplastic anemia in humans. Hydroquinone (HQ), a toxic bone marrow (BM) metabolite of BZ, causes time- and concentration-dependent inhibition of processing of the 34-Kd pre-interleukin-1 alpha (IL-1 alpha) to the 17-Kd mature cytokine in murine P388D1 macrophages and BM stromal macrophages, as measured by Western immunoblots of cell lysate proteins using a polyclonal rabbit antimurine IL-1 alpha antibody. HQ over a 10-fold concentration range had no effect on the lipopolysaccharide (LPS)-induced production of pre- IL-1 alpha precursor or on cell viability or DNA and protein synthesis. Stromal macrophages obtained from the femoral BM of C57Bl/6 mice exposed to BZ (600 or 800 mg/kg body weight) for 2 days were incapable of processing the 34-Kd pre-IL-1 alpha to the mature 17-Kd cytokine when stimulated in culture with LPS. Stromal macrophages from mice coadministered BZ and indomethacin, a prostaglandin H synthase (PHS) inhibitor that has been shown to prevent BZ-induced myelotoxic and genotoxic effects in mice when coadministered with benzene were able to convert the pre-IL-1 alpha to mature cytokine. Administration of recombinant murine IL-1 alpha (rMuIL-1 alpha) to mice before a dose of BZ that causes severe depression of BM cellularity completely prevents BM depression, most probably by bypassing the inability of the stromal macrophage in BZ-treated animals to process pre-IL-1 alpha to the mature cytokine.  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