收费全文 | 37959篇 |
免费 | 1710篇 |
国内免费 | 302篇 |
耳鼻咽喉 | 290篇 |
儿科学 | 672篇 |
妇产科学 | 422篇 |
基础医学 | 5016篇 |
口腔科学 | 1070篇 |
临床医学 | 2207篇 |
内科学 | 9366篇 |
皮肤病学 | 919篇 |
神经病学 | 2664篇 |
特种医学 | 1320篇 |
外科学 | 6783篇 |
综合类 | 153篇 |
一般理论 | 1篇 |
预防医学 | 1063篇 |
眼科学 | 652篇 |
药学 | 2225篇 |
中国医学 | 126篇 |
肿瘤学 | 5022篇 |
2023年 | 209篇 |
2022年 | 551篇 |
2021年 | 904篇 |
2020年 | 465篇 |
2019年 | 673篇 |
2018年 | 869篇 |
2017年 | 686篇 |
2016年 | 790篇 |
2015年 | 831篇 |
2014年 | 1120篇 |
2013年 | 1423篇 |
2012年 | 2290篇 |
2011年 | 2681篇 |
2010年 | 1518篇 |
2009年 | 1239篇 |
2008年 | 2306篇 |
2007年 | 2541篇 |
2006年 | 2374篇 |
2005年 | 2549篇 |
2004年 | 2461篇 |
2003年 | 2451篇 |
2002年 | 2477篇 |
2001年 | 437篇 |
2000年 | 386篇 |
1999年 | 510篇 |
1998年 | 599篇 |
1997年 | 479篇 |
1996年 | 452篇 |
1995年 | 392篇 |
1994年 | 343篇 |
1993年 | 312篇 |
1992年 | 263篇 |
1991年 | 240篇 |
1990年 | 259篇 |
1989年 | 249篇 |
1988年 | 221篇 |
1987年 | 163篇 |
1986年 | 129篇 |
1985年 | 122篇 |
1984年 | 132篇 |
1983年 | 109篇 |
1982年 | 81篇 |
1981年 | 103篇 |
1980年 | 93篇 |
1979年 | 86篇 |
1978年 | 58篇 |
1977年 | 43篇 |
1976年 | 31篇 |
1975年 | 39篇 |
1973年 | 27篇 |
Methods: Hybrid cells containing a fragment of human chromosome 8 in scid cells (RD13B2) were used. DNA-PK activity was measured by an in vitro assay. Immunoprecipitation of the nuclear extract was performed with an anti-Ku80 antibody. Proteins co-precipitated with Ku80 were separated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and detected by Western blotting using anti-heat shock protein (HSP)72 and anti-heat shock cognate protein (HSC)73 antibodies. HSC73 was overexpressed with the pcDNA3.1 vector. Short hairpin (sh)RNA was used to downregulate HSC73 and HSP72.
Results: The activity of heat-inactivated DNA-PK recovered to about 50% of control during an additional incubation at 37?°C after heat treatment at 44?°C for 15?min in the presence of cycloheximide (which inhibits de novo protein synthesis). Maximal recovery was observed within 3?h of incubation at 37?°C after heat treatment. Constitutively expressed HSC73, which folds newly synthesized proteins, reached maximal levels 3?h after heat treatment using a co-immunoprecipitation assay with the Ku80 protein. Inhibiting HSC73, but not HSP72, expression with shRNA decreased the recovery of DNA-PK activity after heat treatment.
Conclusions: These results suggest that de novo protein synthesis is unnecessary for recovery of some heat-inactivated DNA-PK. Rather, it might be reactivated by the molecular chaperone activity of HSC73, but not HSP72. 相似文献
Objective
This study assessed the association between the timing of first epinephrine administration (EA) and the neurological outcomes following out-of-hospital cardiac arrests (OHCAs) with both initial shockable and non-shockable rhythms.Methods
This was a post-hoc analysis of a multicenter prospective cohort study (SOS-KANTO 2012), which registered OHCA patients in the Kanto region of Japan from January 2012 to March 2013. We included consecutive adult OHCA patients who received epinephrine. The primary result included 1-month favorable neurological outcomes defined as cerebral performance category (CPC) 1 or 2. Secondary results included 1-month survival and return of spontaneous circulation (ROSC) after arrival at the hospital. Multivariable logistic regression analysis determined the association between delay per minute of the time from call to first EA in both pre- or in-hospital settings and outcomes.Results
Of the 16,452 patients, 9344 were eligible for our analyses. In univariable analysis, the delay in EA was associated with decreased favorable neurological outcomes only when the initial rhythm was a non-shockable rhythm. In multivariable analyses, delay in EA was associated with decreased ROSC (adjusted odds ratio [OR] for one minute delay, 0.97; 95% confidence interval [CI], 0.96–0.98) and 1-month survival (adjusted OR, 0.95; 95% CI, 0.92–0.97) when the initial rhythm was a non-shockable rhythm, whereas during a shockable rhythm, delay in EA was not associated with decreased ROSC and 1-month survival.Conclusions
While assessing the effectiveness of epinephrine for OHCA, we should consider the time-limited effects of epinephrine. Additionally, consideration of early EA based on the pathophysiology is needed. 相似文献Methods & Procedures: Eighteen PWA and 20 healthy older adults (HOA) completed a written sentence-picture matching task involving the interpretation of prepositional phrases (PP; the chef is poking the solider with an umbrella) that were ambiguous between high (verb modifier) and low attachment (object noun modifier). Only one interpretation was possible for prime sentences, while both interpretations were possible for target sentences. In Experiment 1, the target was presented immediately after the prime (0-lag). In Experiment 2, two filler items intervened between the prime and the target (2-lag). Within each experiment, the verb was repeated for half of the prime-target pairs, while different verbs were used for the other half. Participants’ off-line picture matching choices and response times were measured.
Results: After reading a prime sentence with a particular interpretation, HOA and PWA tended to interpret an ambiguous PP in a target sentence in the same way and with faster response times. Importantly, both groups continued to show this priming effect over a lag (Experiment 2), although the effect was not as reliable in response times. However, neither group showed lexical (verb-specific) boost on priming, deviating from robust lexical boost seen in the young adults of prior studies.
Conclusions: PWA demonstrate abstract (lexically-independent) structural priming in the absence of a lexically-specific boost. Abstract priming is preserved in aphasia, effectively facilitating not only immediate but also longer-lasting structure-message mapping during sentence comprehension. 相似文献