全文获取类型
收费全文 | 19254篇 |
免费 | 1228篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 229篇 |
儿科学 | 630篇 |
妇产科学 | 331篇 |
基础医学 | 2722篇 |
口腔科学 | 539篇 |
临床医学 | 1885篇 |
内科学 | 3615篇 |
皮肤病学 | 338篇 |
神经病学 | 1660篇 |
特种医学 | 1140篇 |
外国民族医学 | 25篇 |
外科学 | 2345篇 |
综合类 | 178篇 |
一般理论 | 6篇 |
预防医学 | 2042篇 |
眼科学 | 215篇 |
药学 | 1584篇 |
1篇 | |
中国医学 | 56篇 |
肿瘤学 | 984篇 |
出版年
2022年 | 147篇 |
2021年 | 269篇 |
2020年 | 186篇 |
2019年 | 240篇 |
2018年 | 306篇 |
2017年 | 240篇 |
2016年 | 269篇 |
2015年 | 337篇 |
2014年 | 415篇 |
2013年 | 580篇 |
2012年 | 828篇 |
2011年 | 859篇 |
2010年 | 499篇 |
2009年 | 507篇 |
2008年 | 810篇 |
2007年 | 772篇 |
2006年 | 803篇 |
2005年 | 777篇 |
2004年 | 703篇 |
2003年 | 690篇 |
2002年 | 658篇 |
2001年 | 577篇 |
2000年 | 610篇 |
1999年 | 512篇 |
1998年 | 283篇 |
1997年 | 236篇 |
1996年 | 216篇 |
1995年 | 212篇 |
1994年 | 242篇 |
1993年 | 302篇 |
1992年 | 608篇 |
1991年 | 564篇 |
1990年 | 456篇 |
1989年 | 335篇 |
1988年 | 316篇 |
1987年 | 314篇 |
1986年 | 250篇 |
1985年 | 305篇 |
1984年 | 226篇 |
1983年 | 169篇 |
1982年 | 139篇 |
1981年 | 140篇 |
1979年 | 172篇 |
1978年 | 141篇 |
1977年 | 135篇 |
1976年 | 145篇 |
1975年 | 152篇 |
1974年 | 182篇 |
1973年 | 156篇 |
1971年 | 137篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Susceptibilities of Campylobacter jejuni isolates from Germany to ciprofloxacin,moxifloxacin, erythromycin,clindamycin, and tetracycline 总被引:1,自引:0,他引:1 下载免费PDF全文
Wagner J Jabbusch M Eisenblätter M Hahn H Wendt C Ignatius R 《Antimicrobial agents and chemotherapy》2003,47(7):2358-2361
To elucidate Campylobacter jejuni resistance to antibiotics in Germany, MICs of ciprofloxacin, moxifloxacin, erythromycin, clindamycin, and tetracycline were determined (using agar dilution) for 144 clinical isolates. The data indicate a considerable ciprofloxacin resistance (45.1%) without a clonal relationship of the strains and a greater in vitro activity of moxifloxacin, erythromycin, and clindamycin. 相似文献
83.
BACKGROUND: To facilitate volume control in neonates, platelets (PLTs) are aliquoted and stored for short periods in non–gas‐permeable syringes before infusion. Although agitation of PLTs during storage in gas‐permeable bags is performed to maintain their quality, the effect of syringe agitation during storage is unknown. STUDY DESIGN AND METHODS: Double apheresis PLTs (n = 6) were collected and split, providing two identical products. On Days 2 and 4 of storage, aliquots from one bag of each pair were transferred to two syringes and stored for 6 hours on flatbed agitator or were left at 20 to 24°C without agitation. A series of in vitro tests was performed on Days 0, 2 (Hours 0 and 6), and 4 (Hours 0 and 6). Control samples were obtained from the second matched bag that was stored on the agitator. Data were analyzed by one‐way analysis of variance with differences considered significant if the p value was less than 0.05. RESULTS: Comparable results for several PLT variables were obtained with or without agitation of the syringes. On Day 4 Hour 6, pH values were 7.18 ± 0.12 (agitated syringes) and 7.19 ± 0.1 (nonagitated syringes), and extent of shape change and hypotonic shock response measurements were not significantly different between agitated syringes and nonagitated syringes (23.7 ± 6.4 and 74.3 ± 9.8% vs. 23.3 ± 5.4 and 76.0 ± 7.6%), respectively. CONCLUSION: Based on in vitro testing, apheresis PLT aliquots can be stored in syringes for at least 6 hours without agitation before transfusions. 相似文献
84.
Jilma B Blann AD Stohlawetz P Eichler HG Kautzky-Willer A Wagner OF 《The Journal of laboratory and clinical medicine》2000,135(3):270-274
Plasma levels of circulating adhesion molecules (AMs) are increased in a number of inflammatory and cardiovascular disorders. Yet the mechanisms regulating the physiologic levels of soluble AMs are largely unknown. It has recently been postulated that glucocorticoids may exert their anti-inflammatory actions partially through the inhibition of cytokine-stimulated expression of E-selectin and intercellular adhesion molecule (ICAM-1). However, it remains controversial whether glucocorticoids affect the basal expression of AMs on resting cells. We have thus evaluated the effects of glucocorticoids by infusing therapeutic doses of dexamethasone (0.04 mg/kg and 1.0 mg/kg twice a day for 2 days) or placebo on plasma levels of circulating E-selectin (cE-selectin), soluble thrombomodulin (sTM), circulating ICAM-1 (cICAM-1), and circulating vascular cell adhesion molecule (cVCAM-1) in 9 healthy men. Plasma was obtained before infusion at 24 and 48 hours. Compared with baseline, levels of cE-selectin decreased by 16% and 22% with the lower and the higher doses, respectively, at 48 hours (P = .007), whereas sTM was unchanged. Both doses of dexamethasone reduced cICAM-1 by about 15% at 48 hours (P = .007), but there were no changes in cVCAM. Dexamethasone time-dependently decreases plasma levels of cE-selectin and cICAM-1 in healthy men. This demonstrates that a glucocorticoid-sensitive mechanism specifically down-regulates normal plasma levels of cE-selectin and cICAM-1 in healthy subjects, which could thus reflect minor baseline inflammation. 相似文献
85.
Roland Pusch Hans‐Joachim Wagner Gerhard von der Emde Jacob Engelmann 《The Journal of comparative neurology》2013,521(17):4075-4093
The retina of the weakly electric fish Gnathonemus petersii is a so‐called grouped retina where photoreceptors are bundled. These bundles are regarded as functional units and this type of retinal specialization is uniquely found in teleosts. To understand how this anatomical organization influences visual information processing we investigated the morphology and distribution of retinal ganglion cells (GCs) and the response properties of retinal afferents terminating in the major retinorecipient area, the optic tectum. GCs were classified based on their dendritic morphology (dendritic field diameters <90–100 μm: narrow‐field GCs; 110–280 μm: widefield GCs; >280 μm: giant GCs). Within these classes subtypes were distinguished based on the ramification patterns of the dendrites in the sublaminae of the inner plexiform layer. Properties of presumed optic nerve terminals were investigated in the optic tectum using extracellular recordings. Physiological classes could be observed based on their response to visual stimuli (on; off; on‐off, and fast units). Receptive field sizes and spatiotemporal properties were classified and the topographical representation of the visual space was mapped in the tectum. Gratings of low spatial frequencies were best responded to and followed up to high temporal frequencies (>30 Hz). Most of the recorded units were directionally selective. No evidence of distorted topographies in the tectum was found, i.e., no overrepresentation of the retina was seen in the tectum opticum. The grouped retina of G. petersii seems to be optimized for the detection of large, fast objects in an environment of low optical quality. J. Comp. Neurol. 521:4075–4093, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
86.
Altitude induced insomnia is a very common symptom in mountaineering. Conventional hypnotics such as benzodiazepines potentially can be associated with untoward side effects because they can impair ventilatory adaptation to hypoxia at altitude. The objective of our study was to evaluate the effect of a alternative potentially sedative drug, L-tryptophan on ventilation at moderate altitude. STUDY DESIGN, METHODS AND RELEVANT RESULTS: Randomised, double blind, placebo controlled crossover trial. Blood gas analysis of 8 healthy subjects was performed before and one hour after oral administration of 500 mg L-tryptophan or placebo at altitudes of 171 m and at 3,000 m. PaO2 and PaCO2 before and after L-Tryptophan or placebo medication did not change significantly at neither level of altitude investigated. CONCLUSION: L-tryptophan does not impair ventilatory adaptation to mild hypoxia at moderate altitude. 相似文献
87.
Girkontaite I Sakk V Wagner M Borggrefe T Tedford K Chun J Fischer KD 《The Journal of experimental medicine》2004,200(11):1491-1501
Marginal zones (MZs) are microdomains in the spleen that contain various types of immune cells, including MZ B cells, MOMA1(+) metallophilic macrophages, and mucosal addressin cell adhesion molecule 1 (MAdCAM-1)(+) endothelial cells. MAdCAM-1(+) and MOMA1(+) cells line the sinus, that separates MZs from splenic follicles. Here we show that a receptor for the lysophospholipid sphingosine-1-phosphate (S1P), S1P(3), is required for normal numbers of splenic immature and MZ B cells, and for S1P-induced chemotaxis of MZ B cells. S1P(3) is also essential for proper alignment of MOMA1(+) macrophages and MAdCAM-1(+) endothelial cells along the marginal sinus. The lack of cohesion of the marginal sinus in S1P(3)(-/-) mice affects MZ B cell functions, as wild-type (WT) MZ B cells migrate more into S1P(3)(-/-) follicles than into WT follicles after treatment with lipopolysaccharide. Additionally, short-term homing experiments demonstrate that WT MZ B cells home to the S1P(3)(-/-) spleen in increased numbers, suggesting a role for the marginal sinus in regulating MZ B cells numbers. Moreover, S1P(3)(-/-) mice are defective in mounting immune responses to thymus-independent antigen type 2 due to defects in radiation-resistant cells in the spleen. These data identify lysophospholipids and the S1P(3) receptor as essential regulators of the MZ sinus and its role as a barrier to the follicle. 相似文献
88.
Adipose-derived mesenchymal cells as a potential cell source for skeletal regeneration 总被引:5,自引:0,他引:5
Recent studies suggest that adipose tissue contains pluripotent cells that are similar to those derived from other tissues, such as bone marrow. Mesenchymal cells isolated from adipose tissue are capable of differentiating along osteogenic, chondrogenic, myogenic, adipogenic and possibly neuronal lineages. Current knowledge of adipose-derived mesenchymal cells is reviewed, with a particular focus on efforts to direct these cells towards bone formation. Cell-based therapies using adipose tissue are anticipated to be of great clinical interest for skeletal tissue repair and regeneration. 相似文献
89.
Dr. I. Wagner M. Habs D. Schmähl H. Amberger U. Bachmann 《Journal of cancer research and clinical oncology》1982,104(1-2):115-131
Summary Colonic tumors were induced in male Sprague-Dawley rats by ten applications of 2 mg/kg/week N-nitrosoacetoxymethyl-methylamine (AMMN) or by three applications of 100 mg/kg/month 1,2-dimethylhydrazine (1,2-DMH). Application of AMMN and 1,2-DMH induced selective colonic tumors in 97% and 29–42% of the initial animals, respectively. Colonic-tumor-bearing animals were subjected to monotherapy with 5-fluorouracil, ftorafur, CGP 6809, and CGP 15'720A. No cures were achieved. The different therapies did not exert any clear influence on the survival time of animals, except for animals pretreated with AMMN and then subjected to ftorafur therapy. 相似文献
90.
BreAnne Osborn Chao-Yang Pan April Hatada Jennifer Hatfield Jenni Wagner Kelly Oakeson Anna Montmayeur Christina Morales Jan Vinj 《Emerging infectious diseases》2022,28(11):2312
We report 5 clustered acute gastroenteritis outbreaks in long-term care facilities in Utah, USA, that were linked to healthcare employees working at multiple facilities. Four outbreaks were caused by norovirus genotype GIX. We recommend continued norovirus surveillance and genotyping to determine contributions of this genotype to norovirus outbreaks. 相似文献