全文获取类型
收费全文 | 1631篇 |
免费 | 133篇 |
国内免费 | 63篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 60篇 |
妇产科学 | 19篇 |
基础医学 | 210篇 |
口腔科学 | 26篇 |
临床医学 | 124篇 |
内科学 | 312篇 |
皮肤病学 | 30篇 |
神经病学 | 85篇 |
特种医学 | 292篇 |
外科学 | 128篇 |
综合类 | 64篇 |
预防医学 | 54篇 |
眼科学 | 67篇 |
药学 | 135篇 |
肿瘤学 | 217篇 |
出版年
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 22篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 24篇 |
2014年 | 33篇 |
2013年 | 34篇 |
2012年 | 45篇 |
2011年 | 47篇 |
2010年 | 53篇 |
2009年 | 49篇 |
2008年 | 63篇 |
2007年 | 62篇 |
2006年 | 59篇 |
2005年 | 66篇 |
2004年 | 52篇 |
2003年 | 39篇 |
2002年 | 40篇 |
2001年 | 54篇 |
2000年 | 42篇 |
1999年 | 52篇 |
1998年 | 69篇 |
1997年 | 71篇 |
1996年 | 64篇 |
1995年 | 66篇 |
1994年 | 38篇 |
1993年 | 45篇 |
1992年 | 40篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 57篇 |
1988年 | 46篇 |
1987年 | 45篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 18篇 |
1983年 | 19篇 |
1982年 | 19篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 21篇 |
1978年 | 10篇 |
1977年 | 16篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1970年 | 5篇 |
1969年 | 5篇 |
排序方式: 共有1827条查询结果,搜索用时 0 毫秒
21.
Zhao P Cao J Zhao LJ Qin ZL Ke JS Pan W Ren H Yu JG Qi ZT 《第二军医大学学报》2006,27(5):506-506
The nucleocapsid (N) protein of SARS-coronavirus (SARS-CoV) is the key protein for the formation of the helical nucleocapsid during virion assembly. This protein is believed to be more conserved than other proteins of the virus, such as spike and membrane glycoprotein. In this study, the N protein of SARS-CoV was expressed in Escherichia coli DHSalpha and identified with pooled sera from patients in the convalescence phase of SARS. A plasmid pCI-N, encoding the full-length N gene of SARS-CoV, was constructed. Expression of the N protein was observed in COS1 cells following transfection with pCI-N. The immune responses induced by intramuscular immunization with pCI-N were evaluated in a murine model. Serum anti-N immunoglobutins and splenocytes proliferative responses against N protein were observed in immunized BALB/c mice. The major immunoglobulin G subclass recognizing N protein was immunoglobulin G2a, and stimulated splenocytes secreted high levels of gamma interferon and IL-2 in response to N protein. More importantly, the immunized mice produced strong delayed-type hypersensitivity (DTH) and CD^8+ CTL responses to N protein. 相似文献
22.
千层塔中三萜成分的研究 总被引:5,自引:0,他引:5
前曾报道自千层塔[Huperzia serrata Thunb.(Trev)=Lycopodium serratum Thunb(Trev.)]中分得具有胆碱酯酶抑制活性的新生物碱——石杉碱甲、石杉碱乙、甲基石杉碱乙及已知生物碱8-deoxyserratinine,serratinine,lycodoline及lycoclavine。为进一步阐明该植物的化学成分,我们对其三萜成分进行了研究。从浙江安吉产的千层塔植物中分到六个石松三萜,其中一个为新化合物,经下述方法推定为serratenediol-21-acetate(Ⅰ)。另五 相似文献
23.
本文报道我国西南产麻黄——丽江麻黄Ephedra likiangensis Florin、匍枝丽江麻黄E.likiangensis f.mairei(Florin)C.Y.Cheng、藏麻黄E.saxatilis Royle ex Florin、山岭麻黄E.gerardiana Wall、垫状山岭麻黄E.gerardiana Var.congesta C.Y.Cheng、矮麻黄E.minuta Florin和异株矮麻黄E.minuta var.dioeca C.Y.Cheng,以及形态组织特征较特殊的宁夏产斑子麻黄E.lepidosperma C.Y.Cheng、新疆产窄膜麻黄E.lomatolepis Schrenk,西藏产西藏中麻黄E.intermedia var.tibetica Stapf的生药形态组织学研究结果。并根据对国产麻黄的生药形态组织学的系统研究结果,分别编写了各种国产麻黄(包括13种3变种1变型)的生药性状和生药显微特征检索表。 相似文献
24.
25.
26.
Thorsten Zenz Markus Kreuz Maxi Fuge Wolfram Klapper Heike Horn Annette M. Staiger Doris Winter Hanne Helfrich Jennifer Huellein Martin‐Leo Hansmann Harald Stein Alfred Feller Peter M?ller Norbert Schmitz Lorenz Trümper Markus Loeffler Reiner Siebert Andreas Rosenwald German Ott Michael Pfreundschuh Stephan Stilgenbauer for the German High‐Grade Non‐Hodgkin Lymphoma Study Group 《International journal of cancer. Journal international du cancer》2017,141(7):1381-1388
TP53 is mutated in 20–25% of aggressive B‐cell lymphoma (B‐NHL). To date, no studies have addressed the impact of TP53 mutations in prospective clinical trial cohorts. To evaluate the impact of TP53 mutation to current risk models in aggressive B‐NHL, we investigated TP53 gene mutations within the RICOVER‐60 trial. Of 1,222 elderly patients (aged 61–80 years) enrolled in the study and randomized to six or eight cycles of CHOP‐14 with or without Rituximab (NCT00052936), 265 patients were analyzed for TP53 mutations. TP53 mutations were demonstrated in 63 of 265 patients (23.8%). TP53 mutation was associated with higher LDH (65% vs. 37%; p < 0.001), higher international prognostic index‐Scores (IPI 4/5 27% vs. 12%; p = 0.025) and B‐symptoms (41% vs. 24%; p = 0.011). Patients with TP53 mutation were less likely to obtain a complete remission CR/CRu (CR unconfirmed) 61.9% (mut) vs. 79.7% (wt) (p = 0.007). TP53 mutations were associated with decreased event‐free (EFS), progression‐free (PFS) and overall survival (OS) (median observation time of 40.2 months): the 3 year EFS, PFS and OS were 42% (vs. 60%; p = 0.012), 42% (vs. 67.5%; p < 0.001) and 50% (vs. 76%; p < 0.001) for the TP53 mutation group. In a Cox proportional hazard analysis adjusting for IPI‐factors and treatment arms, TP53 mutation was shown to be an independent predictor of EFS (HR 1.5), PFS (HR 2.0) and OS (HR 2.3; p < 0.001). TP53 mutations are independent predictors of survival in untreated patients with aggressive CD20+ lymphoma. TP53 mutations should be considered for risk models in DLBCL and strategies to improve outcome for patients with mutant TP53 must be developed. 相似文献
27.
Bone scintigraphy in the reflex sympathetic dystrophy syndrome 总被引:1,自引:0,他引:1
28.
Competitive clonal hematopoiesis in mouse chimeras explained by a stochastic model of stem cell organization 下载免费PDF全文
Many current experimental results show the necessity of new conceptual approaches to understand hematopoietic stem cell organization. Recently, we proposed a novel theoretical concept and a corresponding quantitative model based on microenvironment-dependent stem cell plasticity. The objective of our present work is to subject this model to an experimental test for the situation of chimeric hematopoiesis. Investigating clonal competition processes in DBA/2-C57BL/6 mouse chimeras, we observed biphasic chimerism development with initially increasing but long-term declining DBA/2 contribution. These experimental results were used to select the parameters of the mathematical model. To validate the model beyond this specific situation, we fixed the obtained parameter configuration to simulate further experimental settings comprising variations of transplanted DBA/2-C57BL/6 proportions, secondary transplantations, and perturbation of stabilized chimeras by cytokine and cytotoxic treatment. We show that the proposed model is able to consistently describe the situation of chimeric hematopoiesis. Our results strongly support the view that the relative growth advantage of strain-specific stem cells is not a fixed cellular property but is sensitively dependent on the actual state of the entire system. We conclude that hematopoietic stem cell organization should be understood as a flexible, self-organized rather than a fixed, preprogrammed process. 相似文献
29.
Ortiz-Alvarez O; Cabral D; Prendiville JS; Stringer D; Petty RE; Malleson PN 《Rheumatology (Oxford, England)》1997,36(2):280-284
Two children are reported in whom intestinal pseudo-obstruction was the
initial manifestation of systemic sclerosis. Gastrointestinal symptoms and
skin changes resolved or improved in both children following treatment with
prednisone and penicillamine (case 1) or methotrexate (case 2), although
radiological changes of the gastrointestinal tract persisted at 3 and 2 yr
of follow-up, respectively.
相似文献
30.
The PCBP1 gene encoding poly(rc) binding protein i is recurrently mutated in Burkitt lymphoma 下载免费PDF全文
Rabea Wagener Sietse M. Aukema Matthias Schlesner Andrea Haake Birgit Burkhardt Alexander Claviez Hans G. Drexler Michael Hummel Markus Kreuz Markus Loeffler Maciej Rosolowski Cristina Lpez Peter Mller Julia Richter Marius Rohde Matthew J. Betts Robert B. Russell Stephan H. Bernhart Steve Hoffmann Philip Rosenstiel Markus Schilhabel Monika Szczepanowski Lorenz Trümper Wolfram Klapper Reiner Siebert 《Genes, chromosomes & cancer》2015,54(9):555-564
The genetic hallmark of Burkitt lymphoma is the translocation t(8;14)(q24;q32), or one of its light chain variants, resulting in IG‐MYC juxtaposition. However, these translocations alone are insufficient to drive lymphomagenesis, which requires additional genetic changes for malignant transformation. Recent studies of Burkitt lymphoma using next generation sequencing approaches have identified various recurrently mutated genes including ID3, TCF3, CCND3, and TP53. Here, by using similar approaches, we show that PCBP1 is a recurrently mutated gene in Burkitt lymphoma. By whole‐genome sequencing, we identified somatic mutations in PCBP1 in 3/17 (18%) Burkitt lymphomas. We confirmed the recurrence of PCBP1 mutations by Sanger sequencing in an independent validation cohort, finding mutations in 3/28 (11%) Burkitt lymphomas and in 6/16 (38%) Burkitt lymphoma cell lines. PCBP1 is an intron‐less gene encoding the 356 amino acid poly(rC) binding protein 1, which contains three K‐Homology (KH) domains and two nuclear localization signals. The mutations predominantly (10/12, 83%) affect the KH III domain, either by complete domain loss or amino acid changes. Thus, these changes are predicted to alter the various functions of PCBP1, including nuclear trafficking and pre‐mRNA splicing. Remarkably, all six primary Burkitt lymphomas with a PCBP1 mutation expressed MUM1/IRF4, which is otherwise detected in around 20–40% of Burkitt lymphomas. We conclude that PCBP1 mutations are recurrent in Burkitt lymphomas and might contribute, in cooperation with other mutations, to its pathogenesis. © 2015 Wiley Periodicals, Inc. 相似文献