全文获取类型
收费全文 | 2369篇 |
免费 | 207篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 48篇 |
妇产科学 | 40篇 |
基础医学 | 339篇 |
口腔科学 | 57篇 |
临床医学 | 289篇 |
内科学 | 380篇 |
皮肤病学 | 32篇 |
神经病学 | 292篇 |
特种医学 | 53篇 |
外科学 | 362篇 |
综合类 | 38篇 |
一般理论 | 12篇 |
预防医学 | 230篇 |
眼科学 | 100篇 |
药学 | 164篇 |
中国医学 | 1篇 |
肿瘤学 | 121篇 |
出版年
2023年 | 19篇 |
2022年 | 46篇 |
2021年 | 70篇 |
2020年 | 46篇 |
2019年 | 51篇 |
2018年 | 73篇 |
2017年 | 33篇 |
2016年 | 49篇 |
2015年 | 51篇 |
2014年 | 71篇 |
2013年 | 84篇 |
2012年 | 138篇 |
2011年 | 130篇 |
2010年 | 76篇 |
2009年 | 61篇 |
2008年 | 113篇 |
2007年 | 153篇 |
2006年 | 123篇 |
2005年 | 117篇 |
2004年 | 117篇 |
2003年 | 87篇 |
2002年 | 110篇 |
2001年 | 49篇 |
2000年 | 57篇 |
1999年 | 44篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 20篇 |
1993年 | 15篇 |
1992年 | 36篇 |
1991年 | 34篇 |
1990年 | 27篇 |
1989年 | 33篇 |
1988年 | 26篇 |
1987年 | 30篇 |
1986年 | 32篇 |
1985年 | 26篇 |
1984年 | 30篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1979年 | 25篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1975年 | 12篇 |
1974年 | 24篇 |
1973年 | 16篇 |
1972年 | 11篇 |
1971年 | 11篇 |
1970年 | 18篇 |
1968年 | 12篇 |
排序方式: 共有2586条查询结果,搜索用时 15 毫秒
61.
Erika Assarsson Jason A. Greenbaum Magnus Sundstr?m Lana Schaffer Jennifer A. Hammond Valerie Pasquetto Carla Oseroff R. Curtis Hendrickson Elliot J. Lefkowitz David C. Tscharke John Sidney Howard Grey Steven R. Head Bjoern Peters Alessandro Sette 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(40):E63-E64
62.
The mechanism of hCG-induced desensitization of the cAMP system was studied in Percoll-purified mouse Leydig cells. Pretreatment of Leydig cells with hCG resulted in a time- and dose-dependent decrease in the capacity of hCG-induced cAMP formation. Maximal desensitization (approximately 90%) was induced by only partial prior stimulation. Desensitization, however, was not observed without a prior increase in cAMP or testosterone production. Pretreatment of the cells with N6,O2'-dibutyryl cAMP (DBcAMP) also induced a dose- and time-dependent densensitization. cAMP was only effective in the presence of the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (MIX). Cholera toxin desensitized the hormone-induced cAMP response as drastically as hCG. Cholera toxin was unable to reverse the refractory state induced by one of the agonists. hCG-induced desensitization was not associated with a loss in [125I]hCG binding or an increase in maximal phosphodiesterase activity, and appeared not to be dependent on protein synthesis. Membranes from hCG, cholera toxin of DBcAMP-desensitized cells showed an impaired adenylate cyclase activity in response to hCG, hCG plus beta-gamma-imidoguanosine 5'-triphosphate (GPPNP) and NaF. In conclusion, hCG-induced desensitization of the adenylate cyclase system in mouse Leydig cells can be mimicked by cholera toxin, DBcAMP and cAMP, indicating a cAMP-mediated process. The site of the 'lesion' has to be localized to the guanine nucleotide regulatory protein-adenylate cyclase complex rather than to its uncoupling from the hormone receptor. 相似文献
63.
64.
Adna Ai Jasminka Prguda-Muji Lana Salihefendi Larisa Bei Daria Ler Ivana eko Almira Hadovi-Duvo Sead Jai Rijad Konjhodi Damir Marjanovi 《Archives of Medical Science》2021,17(3):823
IntroductionSerological detection of SARS-CoV-2-specific immunoglobulins G (IgG) and M (IgM) antibodies is becoming increasingly important in the management of the COVID-19 pandemic.MethodsWe report the first results of COVID-19 serological testing in Bosnia and Herzegovina on 2841 samples collected and analysed in 2 medical institutions in Sarajevo. Antibody detection was performed using commercially available kits.ResultsIn the first cohort, 43 IgM-positive/IgG-negative and 16 IgM-positive/IgG-positive individuals were detected, corresponding to 3.41% of participants having developed antibodies. In the second cohort, 4.28% participants were found to be IgM-negative/IgG-positive.ConclusionsOur results suggest the need for population-wide serological surveying in Bosnia and Herzegovina. 相似文献
65.
66.
Replication of simian virus 40 origin-containing DNA in vitro with purified proteins. 总被引:53,自引:15,他引:53
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
C R Wobbe L Weissbach J A Borowiec F B Dean Y Murakami P Bullock J Hurwitz 《Proceedings of the National Academy of Sciences of the United States of America》1987,84(7):1834-1838
Simian virus 40 (SV40) DNA replication dependent on the SV40 origin of replication and the SV40 large tumor (T) antigen has been reconstituted in vitro with purified protein components isolated from HeLa cells. In addition to SV40 T antigen, these components included the DNA polymerase alpha-primase complex, topoisomerase I, and a fraction that contained a single-stranded DNA binding protein. The latter protein, which sediments at 5.1 S on glycerol gradients and copurifies with two major protein species of 72 and 76 kDa, was isolated solely by its ability to support SV40 DNA replication. The purified system retained the species-specific DNA polymerase alpha-primase requirement previously observed with crude fractions; the complex from HeLa cells supported SV40 replication, whereas that from calf thymus and mouse cells did not. DNA containing the polyomavirus origin of replication was replicated in a system containing polyomavirus T antigen, the HeLa single-stranded DNA binding protein-containing fraction, and DNA polymerase alpha-primase complex from mouse, but not HeLa, cells. While crude fractions yielded closed circular duplex DNA, none was detected with the purified system. Nevertheless, the addition of a crude fraction to the purified system yielded closed circular monomer products. 相似文献
67.
Introduction
Patients on warfarin with sub-optimal time-in-therapeutic-range (TTR) are more likely to have adverse events. Target-specific oral anticoagulants (TSOACs) are approved and can be used as an alternative to warfarin for a number of indications. Further, the efficacy and safety profiles of the TSOACs compared to warfarin are more favourable when the TTR is ≤ 65% for certain indications.Objective
We aimed to determine simple, sensitive and specific diagnostic tools to identify TTR ≤ 65% during the initial three months of warfarin therapy.Methods
A cross-sectional study including patients newly initiated on warfarin without any interruption for three months was conducted. TTR was calculated using the Rosendaal method. Patients were stratified by TTR (≤ 65% or > 65%). Number of INR measurements, dose changes and INR measurements of ≤ 1.7 or ≥ 4.0 were evaluated as potential diagnostic tools to identify TTR ≤ 65%.Results
670 patients were included. The most common indication for anticoagulation was venous thromboembolism. The mean TTR in the first three months was 68 ± 21% (Range: 10 to 100%). Three or more dose changes identified TTR ≤ 65% and demonstrated a sensitivity and specificity of 90% (95%CI 86 to 93%) and 56% (95%CI 51 to 61%), respectively. Three or more INR measurements of ≤ 1.7 during the initial three months of anticoagulation showed a sensitivity and specificity of 37% (95%CI 32 to 43%) and 98% (95%CI 96 to 99%), respectively.Conclusion
Three or more dose changes and three or more INR measurements of ≤ 1.7 could identify patients with a TTR ≤ 65% in the first three months of warfarin therapy. 相似文献68.
69.
70.