全文获取类型
收费全文 | 25479篇 |
免费 | 1573篇 |
国内免费 | 64篇 |
专业分类
耳鼻咽喉 | 267篇 |
儿科学 | 626篇 |
妇产科学 | 468篇 |
基础医学 | 3720篇 |
口腔科学 | 728篇 |
临床医学 | 2302篇 |
内科学 | 4808篇 |
皮肤病学 | 505篇 |
神经病学 | 2426篇 |
特种医学 | 1335篇 |
外国民族医学 | 25篇 |
外科学 | 3321篇 |
综合类 | 214篇 |
一般理论 | 9篇 |
预防医学 | 2356篇 |
眼科学 | 505篇 |
药学 | 2035篇 |
中国医学 | 71篇 |
肿瘤学 | 1395篇 |
出版年
2022年 | 229篇 |
2021年 | 387篇 |
2020年 | 241篇 |
2019年 | 333篇 |
2018年 | 405篇 |
2017年 | 333篇 |
2016年 | 399篇 |
2015年 | 488篇 |
2014年 | 641篇 |
2013年 | 870篇 |
2012年 | 1267篇 |
2011年 | 1365篇 |
2010年 | 792篇 |
2009年 | 764篇 |
2008年 | 1326篇 |
2007年 | 1308篇 |
2006年 | 1292篇 |
2005年 | 1264篇 |
2004年 | 1178篇 |
2003年 | 1165篇 |
2002年 | 1105篇 |
2001年 | 653篇 |
2000年 | 653篇 |
1999年 | 596篇 |
1998年 | 298篇 |
1997年 | 242篇 |
1996年 | 182篇 |
1995年 | 208篇 |
1994年 | 233篇 |
1993年 | 295篇 |
1992年 | 630篇 |
1991年 | 570篇 |
1990年 | 472篇 |
1989年 | 318篇 |
1988年 | 300篇 |
1987年 | 297篇 |
1986年 | 240篇 |
1985年 | 288篇 |
1984年 | 224篇 |
1983年 | 172篇 |
1982年 | 140篇 |
1981年 | 145篇 |
1979年 | 175篇 |
1978年 | 153篇 |
1977年 | 144篇 |
1976年 | 148篇 |
1975年 | 151篇 |
1974年 | 197篇 |
1973年 | 163篇 |
1971年 | 140篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
H. Klüter I. Dörges E. Maass T. Wagner H. Bartels H. Kirchner 《Annals of hematology》1996,73(2):85-89
Random-donor platelet concentrates (PC) prepared from pooled buffy coats have recently been described as an alternative method
for platelet preparation. We evaluated such PCs in the clinical setting compared with a standard PC from platelet apheresis.
PCs were prepared either from pools of buffy coats (BC-PC) or from single donors (SD-PC) with the cell separator CS-3000 plus.
PCs were stored for up to 5 days before transfusion. We compared fresh PC (day 1) with stored (day 2–3) and long-stored PC
(day 4–5). For analysis, platelet increment in the recipient was determined immediately and 16–22 h (mean 20 h) after transfusion,
corrected for total body area and transfused platelets (CCI). A total of 316 PCs were administered to 36 thrombocytopenic
patients suffering from various hematological disorders. Patients with detectable HLA or platelet-specific antibodies or splenomegaly
were excluded from the study. Mean platelet content of the PC was 262×109 for BC-PC and 251×109 for SD-PC. The 20-h CCI after transfusion of fresh PC was slightly higher with BC-PC than with SD-PC (14.5 versus 11.9;p=0.19), but values did not differ significantly between the two types of PC on any day of storage. For BC-PC, 20-h CCI decreased
with further storage by 30% (10.2;p=0.02). For SD-PC a decrease by 9% was not significant. In conclusion, platelet concentrates prepared from pools of buffy
coats showed excellent transfusion results when administered fresh, but storage decreased the CCI by 30%. No significant difference
from PCs from plateletpheresis was observed on any day of storage. Both types of platelet concentrates were capable of sufficient
platelet increment even when stored for up to 5 days.
Received: 28 December 1995 / Accepted: 14 May 1996 相似文献
73.
Abstract –This study investigated whether two new composite dental indicators -"the number of functioning teeth" and "the number of sound-equivalent teeth" are more efficient than the conventional DM FT index in revealing the social and behavioural factors which are significantly related to oral health status. The arbitrary set of weights given to the T-Health indicator was also evaluated. The number of functioning teeth was defined as the aggregate of filled (otherwise sound) and sound teeth. The T-Health was defined as a weighted average of sound teeth, filled (otherwise sound) teeth and teeth with some decay, the weights intended in principle to represent the relative amounts of sound tissue in these three categories of teeth. An arbitrary set of weights was used: 4, 2, and 1 for sound, filled, and decayed teeth, respectively. 164 families (father, mother and at least one 13-yr-old child) from Belo Horizonte, Brazil, were randomly selected from 13-yr-old children from private and state schools. The parents'ages ranged from 35 to 44 yr. Socio-economic status, area of residence, level of education, family income, sugar consumption, toothbrushing frequency and type of dental attendance were the social and behavioural oral health risk-factors considered in this study. The results indicated that the two new dental indicators are more sensitive to the influence of social and behavioural factors, such as those investigated here, than is the traditional DM FT index. A different set of weights (4, I, and I for sound, filled, and decayed) was suggested for the construction of the T-Health. 相似文献
74.
75.
76.
Minor Iridoid and Phenol Glycosides of Picrorhiza kurrooa 总被引:3,自引:0,他引:3
From the roots of PICRORHIZA KURROOA a new iridoid glycoside, 6-feruloylcatalpol has been isolated, along with veronicoside and minecoside and two phenol glucosides, picein and androsin. 相似文献
77.
78.
Functional analysis of the cag pathogenicity island in Helicobacter pylori isolates from patients with gastritis, peptic ulcer, and gastric cancer 总被引:9,自引:0,他引:9 下载免费PDF全文
Backert S Schwarz T Miehlke S Kirsch C Sommer C Kwok T Gerhard M Goebel UB Lehn N Koenig W Meyer TF 《Infection and immunity》2004,72(2):1043-1056
Helicobacter pylori is the causative agent of a variety of gastric diseases, but the clinical relevance of bacterial virulence factors is still controversial. Virulent strains carrying the cag pathogenicity island (cagPAI) are thought to be key players in disease development. Here, we have compared cagPAI-dependent in vitro responses in H. pylori isolates obtained from 75 patients with gastritis, peptic ulcer, and gastric cancer (n = 25 in each group). AGS gastric epithelial cells were infected with each strain and assayed for (i) CagA expression, (ii) translocation and tyrosine phosphorylation of CagA, (iii) c-Src inactivation, (iv) cortactin dephosphorylation, (v) induction of actin cytoskeletal rearrangements associated with cell elongation, (vi) induction of cellular motility, and (vii) secretion of interleukin-8. Interestingly, we found high but similar prevalences of all of these cagPAI-dependent host cell responses (ranging from 56 to 80%) among the various groups of patients. This study revealed CagA proteins with unique features, CagA subspecies of various sizes, and new functional properties for the phenotypic outcomes. We further showed that induction of AGS cell motility and elongation are two independent processes. Our data corroborate epidemiological studies, which indicate a significant association of cagPAI presence and functionality with histopathological findings in gastritis, peptic ulcer, and gastric cancer patients, thus emphasizing the importance of the cagPAI for the pathogenicity of H. pylori. Nevertheless, we found no significant association of the specific H. pylori-induced responses with any particular patient group. This may indicate that the determination of disease development is highly complex and involves multiple bacterial and/or host factors. 相似文献
79.
Joel D. Schiff Norbert I. A. Overweg 《Pflügers Archiv : European journal of physiology》1980,389(1):75-79
The effects of changing bathing medium osmolality on tension generation in smooth muscle were studied on potassium-depolarized segments of rat ileum. Increasing the tonicity of the medium evokes a transient relaxation of the smooth muscle; restoration of isotonicity evokes a transient contraction of similar amplitude and time course. While immersed in hypertonic media of less than 1.3 times normal tonicity, the smooth muscle slowly increases its isometric tension; in media of nearly twice normal tonicity, the smooth muscle loses tension. All of these effects occur whether the medium is made hypertonic with added NaCl or sucrose. 相似文献
80.
René?G?ddeEmail author Stefanie?Brune Peter?Jagiello Eckhart?Sindern Michael?Haupts Sebastian?Schimrigk Norbert?Müller J?rg?T?Epplen 《Journal of negative results in biomedicine》2005,4(1):7
Apoptosis, the programmed death of cells, plays a distinct role in the etiopathogenesis of Multiple sclerosis (MS), a common
disease of the central nervous system with complex genetic background. Yet, it is not clear whether the impact of apoptosis
is due to altered apoptotic behaviour caused by variations of apoptosis-related genes. Instead, apoptosis in MS may also represent
a secondary response to cellular stress during acute inflammation in the central nervous system. Here, we screened 202 apoptosis-related
genes for association by genotyping 202 microsatellite markers in initially 160 MS patients and 160 controls, both divided
in 4 sets of pooled DNA samples, respectively. When applying Bonferroni correction, no significant differences in allele frequencies
were detected between MS patients and controls. Nevertheless, we chose 7 markers for retyping in individual DNA samples, thereby
eliminating 6 markers from the list of candidates. The remaining candidate, the ERBB3 gene microsatellite, was genotyped in additional 245 MS patients and controls. No association of the ERBB3 marker with the disease was detected in these additional cohorts. In consequence, we did not find further evidence for apoptosis-related
genes as predisposition factors in MS. 相似文献