全文获取类型
收费全文 | 1935篇 |
免费 | 93篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 68篇 |
妇产科学 | 53篇 |
基础医学 | 208篇 |
口腔科学 | 40篇 |
临床医学 | 204篇 |
内科学 | 456篇 |
皮肤病学 | 19篇 |
神经病学 | 116篇 |
特种医学 | 85篇 |
外科学 | 283篇 |
综合类 | 24篇 |
一般理论 | 2篇 |
预防医学 | 125篇 |
眼科学 | 73篇 |
药学 | 145篇 |
中国医学 | 21篇 |
肿瘤学 | 89篇 |
出版年
2023年 | 18篇 |
2022年 | 43篇 |
2021年 | 93篇 |
2020年 | 52篇 |
2019年 | 63篇 |
2018年 | 56篇 |
2017年 | 46篇 |
2016年 | 60篇 |
2015年 | 65篇 |
2014年 | 74篇 |
2013年 | 107篇 |
2012年 | 176篇 |
2011年 | 138篇 |
2010年 | 69篇 |
2009年 | 55篇 |
2008年 | 116篇 |
2007年 | 122篇 |
2006年 | 102篇 |
2005年 | 95篇 |
2004年 | 66篇 |
2003年 | 49篇 |
2002年 | 58篇 |
2001年 | 43篇 |
2000年 | 27篇 |
1999年 | 17篇 |
1998年 | 20篇 |
1997年 | 12篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 15篇 |
1991年 | 11篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 4篇 |
排序方式: 共有2031条查询结果,搜索用时 187 毫秒
61.
Major depressive disorder has been associated with blunted responsiveness to rewards, but inconsistencies exist whether such abnormalities persist after complete remission. To address this issue, across two independent studies, 47 adults with remitted major depressive disorder (rMDD) and 37 healthy controls completed a Probabilistic Reward Task, which used a differential reinforcement schedule of social or monetary feedback to examine reward responsiveness (i.e., ability to modulate behavior as a function of reinforcement history). Relative to controls, adults with rMDD showed blunted reward responsiveness. Importantly, a history of depression predicted reduced reward learning above and beyond residual depressive (including anhedonic) symptoms and perceived stress. Findings indicate that blunted reward responsiveness endures even when adults are in remission and might be a trait-related abnormality in MDD. More research is warranted to investigate if blunted reward responsiveness may predict future depressive episodes and whether targeting reward-related deficits may prevent the re-occurrence of the disorder. 相似文献
62.
63.
64.
Alice T. Sawyer Gabrielle I. Liverant Janie J. Jun Daniel J. Lee Andrew L. Cohen Sunny J. Dutra Diego A. Pizzagalli Denise M. Sloan 《Journal of traumatic stress》2016,29(4):374-378
Learning processes have been implicated in the development and course of posttraumatic stress disorder (PTSD); however, little is currently known about punishment‐based learning in PTSD. The current study investigated impairments in punishment‐based learning in U.S. veterans. We expected that veterans with PTSD would demonstrate greater punishment‐based learning compared to a non‐PTSD control group. We compared a PTSD group with and without co‐occurring depression (n = 27) to a control group (with and without trauma exposure) without PTSD or depression (n = 29). Participants completed a computerized probabilistic punishment‐based learning task. Compared to the non‐PTSD control group, veterans with PTSD showed significantly greater punishment‐based learning. Specifically, there was a significant Block × Group interaction, F(1, 54) = 4.12, p = .047, η2 = .07. Veterans with PTSD demonstrated greater change in response bias for responding toward a less frequently punished stimulus across blocks. The observed hypersensitivity to punishment in individuals with PTSD may contribute to avoidant responses that are not specific to trauma cues. 相似文献
65.
66.
67.
Chhabra M Mittal V Jaiswal R Malik S Gupta M Lal S 《Indian journal of medical microbiology》2007,25(3):263-266
In vitro isolation of rabies virus using mouse neuroblastoma cells (MNA) was evaluated. The sensitivity and reliability of in vitro procedure was performed in comparison with mouse inoculation test (MIT), the in vivo method of virus isolation, direct fluorescent antibody test (FAT) and Sellers staining. Of the 33 animal brain samples tested, 24 (72.72%) were positive by MIT. Sensitivity of Sellers stain, FAT and rapid tissue culture infection test (RTCIT) was found to be 54.16, 100 and 91.6% respectively. Concordance of Sellers stain, FAT, RTCIT with MIT was found to be 66.6, 100 and 93.93% respectively. Two samples which were positive by FAT and MIT showed gross contamination in cell lines, which is one of the drawbacks of RTCIT. However, rabies virus could be isolated in MNA cells from two of the eight human cerebrospinal fluid (CSF) samples from clinico-epidemiologically suspected cases of rabies. Both MIT and FAT showed negative results in the two CSF samples. RTCIT appears to be a fast and reliable alternative to MIT and holds promise in antemortem diagnosis of rabies, which is otherwise, a challenging task for a reference laboratory. 相似文献
68.
Reticuloendotheliosis virus (REV) causes runting, high mortality, immunosuppression, and chronic neoplasia associated with T and/or B cell lymphomas in a variety of domestic and wild birds, including Attwater's prairie chickens (APC) (Tympanuchus cupido attwateri). The complete proviral sequence of a recent REV isolate from APC (REV APC-566) was determined. This virus was isolated from an APC maintained in captivity in a reproduction program intended to avoid its extinction. REV APC-566 was determined to be oncogenic in Japanese quail (Coturnix coturnix japonica), chickens (Gallus gallus) and turkeys (Meleagris gallopavo). Immune responses against bacteria and viruses were significantly reduced in turkeys infected with REV APC-566. The proviral genome is 8286 nucleotides in length and exhibits a genetic organization characteristic of replication-competent gammaretroviruses. The REV APC-566 provirus contains two identical long terminal repeats (LTR) and a complete set of genes including gag, gag-pol and env. As previously reported, alignments with other REV sequences showed high similarity with sequences found in the gag and pol genes from other REVs. The REV APC-566 env gene showed high nucleotide sequence homology with REV sequences inserted in fowl poxvirus (99.8%), and with spleen necrosis virus (SNV) (95.1%). Sequences coding for a previously reported immunosuppressive peptide contained in the transmembrane region of the env gene are well conserved among all REV sequences analyzed. The LTR was the most divergent region, exhibiting various deletions and insertions. REV APC-566 has a unique insertion of 23 bp in U3 and shares deletions of 19 and 5 bp with chicken syncytial virus and REV inserts in fowlpox virus. 相似文献
69.
Sahithi Ravuluri Rohit Bansal Nidhi Chhabra Anurag S. Rathore 《Pharmaceutical research》2018,35(7):142
Purpose
To understand non-enzymatic hydrolytic fragmentation of a monoclonal antibody therapeutic under temperature stressed conditions and investigating possible mechanism for the same.Methods
The mAb therapeutic was incubated at 50°C in phosphate buffer at pH 6.5 and fragmentation was monitored at different ionic strengths under stressed conditions. The incubated mAb was sampled at regular time intervals by analytical Size Exclusion Chromatography (SEC).Results
It was observed that 57% of the mAb product fragmented over 4 days into two fragment species – Fc-Fab and Fab with molecular weights of 97 KDa and 47 KDa, respectively, as measured by mass spectrometry (MS) and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The fragmentation rate was slow initially and then accelerated with time. No change in % aggregate level was observed in this duration, implying that degradation was primarily via fragmentation at high temperature. Kinetics of hydrolytic fragmentation was hypothesized and SEC data was fitted to estimate the kinetic rate constants. While degradation of the monomer into fragment species was non-Arrhenius with a negative activation energy, further degradation of Fab-Fc fragments into Fab or Fc fragments followed Arrhenius Law with an activation energy of 2.1 and 15.38 kcal/mol, respectively.Conclusion
High temperature (50°C) causes mAb to cleave at the hinge region to form Fab-Fc and Fab/Fc, as confirmed by dynamic light scattering, SDS-PAGE, SEC, and MS. A kinetic model for hydrolytic fragmentation has been proposed. The results are expected to assist end users in formulation development as well as in monitoring stability of biotherapeutic products.70.
Gary Tse Mengqi Gong Sunny Hei Wong William K.K. Wu George Bazoukis Konstantinos Lampropoulos Wing Tak Wong Yunlong Xia Martin C.S. Wong Tong Liu Jean Woo 《Journal of the American Medical Directors Association》2018,19(3):255-261.e1