全文获取类型
收费全文 | 1188篇 |
免费 | 120篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 22篇 |
妇产科学 | 11篇 |
基础医学 | 109篇 |
口腔科学 | 4篇 |
临床医学 | 191篇 |
内科学 | 301篇 |
皮肤病学 | 5篇 |
神经病学 | 104篇 |
特种医学 | 48篇 |
外科学 | 237篇 |
综合类 | 55篇 |
一般理论 | 1篇 |
预防医学 | 63篇 |
眼科学 | 18篇 |
药学 | 36篇 |
中国医学 | 5篇 |
肿瘤学 | 82篇 |
出版年
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 10篇 |
2016年 | 12篇 |
2015年 | 18篇 |
2014年 | 16篇 |
2013年 | 19篇 |
2012年 | 33篇 |
2011年 | 33篇 |
2010年 | 39篇 |
2009年 | 29篇 |
2008年 | 41篇 |
2007年 | 68篇 |
2006年 | 49篇 |
2005年 | 41篇 |
2004年 | 44篇 |
2003年 | 46篇 |
2002年 | 54篇 |
2001年 | 38篇 |
2000年 | 38篇 |
1999年 | 34篇 |
1998年 | 26篇 |
1997年 | 23篇 |
1996年 | 28篇 |
1995年 | 13篇 |
1994年 | 33篇 |
1993年 | 18篇 |
1992年 | 46篇 |
1991年 | 31篇 |
1990年 | 41篇 |
1989年 | 54篇 |
1988年 | 32篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 24篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1974年 | 10篇 |
1973年 | 13篇 |
1972年 | 7篇 |
排序方式: 共有1332条查询结果,搜索用时 0 毫秒
71.
72.
73.
B-CLL cells are capable of synthesis and secretion of both pro- and anti-angiogenic molecules. 总被引:8,自引:0,他引:8
N E Kay N D Bone R C Tschumper K H Howell S M Geyer G W Dewald C A Hanson D F Jelinek 《Leukemia》2002,16(5):911-919
Initial work has shown that clonal B cells from B-chronic lymphocytic leukemia (B-CLL) are able to synthesize pro-angiogenic molecules. In this study, our goal was to study the spectrum of angiogenic factors and receptors expressed in the CLL B cell. We used ELISA assays to determine the levels of basic fibroblast growth factors (bFGF), vascular endothelial growth factor (VEGF), endostatin, interferon-alpha (IFN-alpha) and thrombospondin-1 (TSP-1) secreted into culture medium by purified CLL B cells. These data demonstrated that CLL B cells spontaneously secrete a variety of pro- and anti-angiogenic factors, including bFGF (23.9 pg/ml +/- 7.9; mean +/- s.e.m.), VEGF (12.5 pg/ml +/- 2.3) and TSP-1 (1.9 ng/ml +/- 0.3). Out of these three factors, CLL B cells consistently secreted bFGF and TSP-1, while VEGF was expressed in approximately two-thirds of CLL patients. Of interest, hypoxic conditions dramatically upregulated VEGF expression at both the mRNA and protein levels. We also employed ribonuclease protection assays to assay CLL B cell expression of a variety of other angiogenesis-related molecules. These analyses revealed that CLL B cells consistently express mRNA for VEGF receptor 1 (VEGFR1), thrombin receptor, endoglin, and angiopoietin. Further analysis of VEGFR expression by RT-PCR revealed that CLL B cells expressed both VEGFR1 mRNA and VEGFR2 mRNA. In summary, these data collectively indicate that CLL B cells express both pro- and anti-angiogenic molecules and several vascular factor receptors. Because of the co-expression of angiogenic molecules and receptors for some of these molecules, these data suggest that the biology of the leukemic cells may also be directly impacted by angiogenic factors as a result of autocrine pathways of stimulation. 相似文献
74.
75.
Tomographic imaging of the myocardium was performed using a gamma camera and a 30-degree rotating slant-hole collimator to register 64 projections from a restricted-view angle. Section images were reconstructed with a two-dimensional filtered backprojection technique. Performance in terms of resolution, effects of misalignment, and three-dimensional activity distribution was evaluated in phantom studies. In a limited clinical study, ten consecutive patients were imaged both with single-photon emission computed tomography (SPECT) and the method described. In the new method, the camera was orientated in the 30 degrees left anterior oblique position with 15 degrees cranial tilt. Due to the short distance from the myocardium to the camera, resolution within reconstructed section images was high, the noise level was comparatively low, and the mean activity level in the posterior wall was significantly higher (p less than 0.005) than in SPECT. 相似文献
76.
人尿中几种雄激素及蛋白同化激素的HPLC测定 总被引:3,自引:0,他引:3
对HPLC分离及定量测定人尿中雄激素及蛋白同化激素的方法进行了初步研究。确定了六种甾体激素的分离条件及内标定量方法。固定相为C8键合硅胶,甲醇—乙腈—水(4:5:6)恒溶剂洗脱,程序流速。紫外检测器波长254 nm。检测限可至1 ng以下。本法采用Sep-Pak C18小柱进行尿样净化,回收率高而且稳定。操作简便快速。对尿样中甾体葡萄糖醛酸甙结合物的酶促水解条件也进行了初步探索。 相似文献
77.
78.
79.
The effect of pulse intravenous methylprednisolone therapy followed by oral immunosuppression was evaluated in ten patients with idiopathic membranous glomerulonephritis who had developed progressive renal failure--a group generally considered to have a poor prognosis. The patients (six male, four female, mean age 50 years) were monitored over 9-30 months during which time creatinine clearance reduced from (mean +/- SEM) 83 +/- 10 to 29 +/- 6 ml/min, and plasma creatinine increased from 135 +/- 22 to 297 +/- 35 mumol/l. All patient were nephrotic with mean 24-h urinary protein excretion ranging from 5.8 to 19.6 g. Treatment administered was pulse intravenous methyl-prednisolone 1 g X 3 then oral prednisolone 30 mg and azathioprine 50 mg (nine patients) or cyclophosphamide 50 mg (one patient). Mean prednisolone dosage was 25 mg at 3 months, 16 mg at 6, and 10 mg at 12 months. Patients have been followed up for between 12 and 57 months on therapy. Creatinine clearance increased to 39 +/- 6, 47 +/- 5 and 48 +/- 18 ml/min after 3, 6 and 12 months treatment with a fall in proteinuria to 6.2 +/- 1.7, 5.7 +/- 1.4, and 3.1 +/- 1.1 g/24h. The deterioration of renal function was reversed in six patients (associated with a reduction in proteinuria to less than 1 g/24 hours in five), slowed in three (with a significant reduction in proteinuria in two), and only one patient with more advanced renal failure before treatment progressed to end-stage failure without any retardation of the rate of deterioration or change in proteinuria.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
80.
R Rustom P Maltby J S Grime H R Stockdale M Critchley J M Bone 《Clinical science (London, England : 1979)》1992,83(3):295-299
1. Aprotinin (Trasylol) is a cationic 6500 Da polypeptide that inhibits proteolytic enzymes, and when labelled with 99mTc it is a reproducible marker for the renal tubular turnover of small filtered proteins in man. Lysine potently inhibits tubular peptide uptake, and may thus depress the uptake and metabolism of aprotinin. This was investigated in 14 glomerulonephritic patients with normal renal function and variable proteinuria and in one healthy subject. 2. 99mTc-labelled aprotinin was given intravenously alone, and again 3 days later, immediately after the intravenous administration of 3-6 g of lysine, followed by an infusion over 1 h of 0.3-1.9 g of lysine/kg in individual patients. Activity over kidneys and in urine was measured over 24 h and chromatography was used to separate the undegraded peptide from free isotope. 3. At the low dosage of lysine (< 0.8 g/kg) given to six patients, kidney activity (representing tubular uptake) was unchanged, but early urine samples contained some undegraded aprotinin. Urinary excretion of free isotope, representing tubular metabolism, fell from 1.6 +/- 0.2% of dose/h with no lysine to 0.9 +/- 0.1% of dose/h in the 24 h after lysine, suggesting suppression of tubular aprotinin degradation. Corrected fractional degradation was calculated from the mean urinary excretion of free isotope over a given interval, determined by chromatography, divided by the mean cumulative kidney counts over this same interval, and this also fell after lysine from 0.06 +/- 0.006 to 0.03 +/- 0.006 h-1 (P < 0.005) between 3.75 and 24 h.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献