全文获取类型
收费全文 | 1592篇 |
免费 | 82篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 158篇 |
妇产科学 | 40篇 |
基础医学 | 266篇 |
口腔科学 | 42篇 |
临床医学 | 121篇 |
内科学 | 310篇 |
皮肤病学 | 30篇 |
神经病学 | 193篇 |
特种医学 | 17篇 |
外科学 | 94篇 |
综合类 | 21篇 |
一般理论 | 1篇 |
预防医学 | 84篇 |
眼科学 | 62篇 |
药学 | 118篇 |
中国医学 | 12篇 |
肿瘤学 | 100篇 |
出版年
2024年 | 2篇 |
2023年 | 14篇 |
2022年 | 13篇 |
2021年 | 46篇 |
2020年 | 23篇 |
2019年 | 40篇 |
2018年 | 28篇 |
2017年 | 34篇 |
2016年 | 44篇 |
2015年 | 43篇 |
2014年 | 67篇 |
2013年 | 78篇 |
2012年 | 128篇 |
2011年 | 129篇 |
2010年 | 83篇 |
2009年 | 79篇 |
2008年 | 97篇 |
2007年 | 105篇 |
2006年 | 94篇 |
2005年 | 108篇 |
2004年 | 86篇 |
2003年 | 81篇 |
2002年 | 80篇 |
2001年 | 24篇 |
2000年 | 23篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 5篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1983年 | 3篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1679条查询结果,搜索用时 15 毫秒
31.
32.
Nicole Schupf Sandra Barral Thomas Perls Anne Newman Kaare Christensen Bharat Thyagarajan Michael Province Winifred K. Rossi Richard Mayeux 《Neurobiology of aging》2013
Exceptional longevity is associated with substantial heritability. The ?4 allele in apolipoprotein E and the linked G allele in rs2075650 of TOMM40 have been associated with increased mortality and the ?2 allele with decreased mortality, although inconsistently. Offspring from long-lived families and spouse controls were recruited at 3 sites in the United States and Denmark. We used generalized estimating equations to compare the likelihood of carrying risk alleles in offspring (n = 2307) and spouse controls (n = 764), adjusting for age, sex, level of education, and family membership. The likelihood of carrying an APOE ?4 allele or a G allele in rs2075650 was lower (odds ratio [OR], 0.75; p = 0.005 and OR, 0.70; p = 0.002) and the likelihood of carrying an APOE ?2 allele was higher (OR, 1.5; p = 0.007) among family members in the offspring generation than among their spouse controls. Our findings support the hypothesis that both reduction in the frequency of the ?4 allele and increase in the frequency of the ?2 allele contribute to longevity. 相似文献
33.
Sathyaprasad Savitha S. M. Sharma Shetty Veena R. Rekha 《Indian Journal of Plastic Surgery》2015,48(2):159-164
Background:
The bone morphogenetic protein (BMP) signalling pathway is crucial in a number of developmental processes and is critical in the formation of variety of craniofacial elements including cranial neural crest, facial primordium, tooth, lip and palate. It is an important mediator in regulation of lip and palate fusion, cartilage and bone formation.Aim:
To study the role of mutation of BMP4 genes in the aetiology of non-syndromic cleft lip with or without palate (NSCL ± P) and identify it directly from human analyses.Materials and Methods:
A case-control study was done to evaluate whether BMP4T538C polymorphism, resulting in an amino acid change of Val=Ala (V152A) in the polypeptide, is associated with NSCL ± P in an Indian paediatric population. Genotypes of 100 patients with NSCL ± P and 100 controls (in whom absence of CL ± P was confirmed in three generations) were detected using a polymerase chain reaction-restriction fragment length polymorphism strategy. Logistic regression was performed to evaluate allele and genotype association with NSCLP.Results:
Results showed significant association between homozygous CC genotype with CL ± P (odds ratio [OR]-5.59 and 95% confidence interval [CI] = 2.85-10.99). The 538C allele carriers showed an increased risk of NSCL ± P as compared with 538 T allele (OR - 4.2% CI = 2.75-6.41).Conclusion:
This study suggests an association between SNP of BMP4 gene among carriers of the C allele and increased risk for NSCLP in an Indian Population. Further studies on this aspect can scale large heights in preventive strategies for NSCLP that may soon become a reality.KEY WORDS: Aetiology of non-syndromic cleft lip and palate, bone morphogenetic protein 4 gene, bone morphogenetic protein gene 相似文献34.
Kevin J. Cheung Veena Padmanaban Vanesa Silvestri Koen Schipper Joshua D. Cohen Amanda N. Fairchild Michael A. Gorin James E. Verdone Kenneth J. Pienta Joel S. Bader Andrew J. Ewald 《Proceedings of the National Academy of Sciences of the United States of America》2016,113(7):E854-E863
Recent genomic studies challenge the conventional model that each metastasis must arise from a single tumor cell and instead reveal that metastases can be composed of multiple genetically distinct clones. These intriguing observations raise the question: How do polyclonal metastases emerge from the primary tumor? In this study, we used multicolor lineage tracing to demonstrate that polyclonal seeding by cell clusters is a frequent mechanism in a common mouse model of breast cancer, accounting for >90% of metastases. We directly observed multicolored tumor cell clusters across major stages of metastasis, including collective invasion, local dissemination, intravascular emboli, circulating tumor cell clusters, and micrometastases. Experimentally aggregating tumor cells into clusters induced a >15-fold increase in colony formation ex vivo and a >100-fold increase in metastasis formation in vivo. Intriguingly, locally disseminated clusters, circulating tumor cell clusters, and lung micrometastases frequently expressed the epithelial cytoskeletal protein, keratin 14 (K14). RNA-seq analysis revealed that K14+ cells were enriched for desmosome and hemidesmosome adhesion complex genes, and were depleted for MHC class II genes. Depletion of K14 expression abrogated distant metastases and disrupted expression of multiple metastasis effectors, including Tenascin C (Tnc), Jagged1 (Jag1), and Epiregulin (Ereg). Taken together, our findings reveal K14 as a key regulator of metastasis and establish the concept that K14+ epithelial tumor cell clusters disseminate collectively to colonize distant organs.During metastasis, cancer cells escape the primary tumor, travel through the circulation, and colonize distant organs. Conventional models of cancer progression propose that each metastasis arises from the clonal outgrowth of a single tumor cell and this conceptual framework is a foundation for models, such as epithelial-mesenchymal transition (EMT) and migratory cancer stem cells (1).Challenging the generality of the single-cell/single-metastasis model are long-standing clinical observations that tumor cell clusters (also termed “tumor clumps”) are also observed across the stages of metastasis. Tumor cell clusters are detected in the bloodstream of cancer patients (2), clusters can efficiently seed metastases (3), and though rare, circulating tumor cell (CTC) clusters have prognostic significance (4, 5). Furthermore, metastases are composed of multiple genetically distinct tumor cell clones, in mouse models of breast, pancreas, and small cell carcinoma (5–7), and in human metastatic prostate cancer patients (8). Taken together, these observations provide accumulating evidence that tumor cell clusters contribute to metastasis. However, they leave unresolved two important questions: how do tumor cell clusters emerge from the primary tumor, and which molecular features identify cell clusters that metastasize?An important clinical observation is that cancer cells invade the surrounding stroma as cohesive clusters in the majority of epithelial tumors, a process termed “collective invasion” (9, 10). In breast cancer, collective invasion is facilitated by invasive leader cells, a subpopulation of tumor cells that highly express keratin 14 (K14) and other basal epithelial markers (11). K14+ cells are migratory, protrusive, and lead trailing K14− cells, while maintaining cell–cell cohesion and E-cadherin–based cell contacts.In this study, we sought to understand how these K14+ cells exit collective invasion strands in the primary tumor and travel to distant organs (12). One hypothesis is that collective invasion is an intermediate step toward eventual single-cell dissemination and monoclonal metastasis. However, tumor cell clusters are detected in circulation (5) and primary human breast tumors can disseminate collectively into the surrounding extracellular matrix in ex vivo assays (13–15). These data prompted an alternative hypothesis, that collectively invading K14+ cancer cells could initiate and complete the metastatic process as a cohesive multicellular unit. Here we define the clonal nature of metastases in a spontaneous mouse model of metastasis to the lungs (16, 17), in which the predominant invasive form in the primary tumor is collective invasion strands led by K14+ cells (11). We establish that the majority of metastases arise from polyclonal seeds, and show that disseminated tumor cell clusters are predominantly composed of K14+ cells. We propose a mechanism for polyclonal metastasis via the collective invasion, dissemination, and colonization of clusters of K14+ cancer cells. 相似文献
35.
Gaurav Sharma Himanshi Kapoor Madhu Chopra Kaushal Kumar Veena Agrawal 《Parasitology research》2014,113(1):197-209
Malaria and dengue are the two most important vector-borne human diseases caused by mosquito vectors Anopheles stephensi and Aedes aegypti, respectively. Of the various strategies adopted for eliminating these diseases, controlling of vectors through herbs has been reckoned as one of the important measures for preventing their resurgence. Artemisia annua leaf chloroform extract when tried against larvae of A. stephensi and A. aegypti has shown a strong larvicidal activity against both of these vectors, their respective LC50 and LC90 values being 0.84 and 4.91 ppm for A. stephensi and 0.67 and 5.84 ppm for A. aegypti. The crude extract when separated through column chromatography using petroleum ether-ethyl acetate gradient (0–100 %) yielded 76 fractions which were pooled into three different active fractions A, B and C on the basis of same or nearly similar R f values. The aforesaid pooled fractions when assayed against the larvae of A. stephensi too reported a strong larvicidal activity. The respective marker compound purified from the individual fractions A, B and C, were Artemisinin, Arteannuin B and Artemisinic acid, as confirmed and characterized through FT-IR and NMR. This is our first report of strong mortality of A. annua leaf chloroform extract against vectors of two deadly diseases. This technology can be scaled up for commercial exploitation. 相似文献
36.
DRB1*0402 may influence arthritis by promoting naive CD4+ T‐cell differentiation in to regulatory T cells
下载免费PDF全文
![点击此处可从《European journal of immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
David Luckey Marshall Behrens Michele Smart Harvinder Luthra Chella S. David Veena Taneja 《European journal of immunology》2014,44(11):3429-3438
HLA‐DRB1*0401 expression in humans has been associated with a predisposition to developing rheumatoid arthritis (RA) and collagen‐induced arthritis (CIA), while HLA‐DRB1*0402 is not associated with susceptibility. Here, we determined if mice transgenic (Tg) for human *0401 have a CD4+ T‐cell repertoire that predetermines proinflammatory cytokine production. The data show that both *0401 and *0402 Tg mice can produce TH1/TH17 cytokines, although the kinetics of response may be different. However, in the context of antigen‐specific responses in a CIA model, *0402 Tg mice generate a TH2 response that may explain their resistance to developing arthritis. In addition, a significant subset of naïve CD4+ T cells from *0402 Tg mice can be activated in polarizing conditions to differentiate into Treg cells that produce IFN‐γ. *0401 Tg mice harbor memory CD4+ T cells that differentiate into IL‐17+ cells in various polarizing conditions. Our data suggest that *0401 Tg mice generate a strong immune response to lipopolysaccharide and may be efficient in clearing infection, and may *0401 have been evolutionarily selected for this ability. Autoimmunity, such as RA, could likely be a bystander effect of the cytokine storm that, along with the presence of low Treg‐cell numbers in *0401 Tg mice, causes immune dysregulation. 相似文献
37.
Ramesh Agarwal Deenanath Virmani Munnalal Jaipal Shuchita Gupta Mari Jeeva Sankar Sunita Bhatia Anand Agarwal Veena Devgan Nandita Gupta Ashok K. Deorari Vinod K. Paul 《Indian journal of pediatrics》2014,81(3):279-282
Serum ferritin levels of low birth weight (LBW; BW?<?2,500 g) and normal birth weight (NBW; BW?≥?2,500 g) infants were evaluated at birth and at 3 mo using electrochemiluminescence immunoassay. At birth, levels were 318.6 (31.0–829.5) ng/mL in LBW (n?=?217) and 366.2 (122.4–858.5) ng/mL in NBW infants (n?=?116; p?<?0.01), with 1.4 % of LBW and none of the NBW infants having levels <12 ng/mL (p?=?0.20). At follow up, levels were 66.9 (4.5–567.7) ng/mL in LBW (n?=?126) and 126.2 (6.8–553.7) ng/mL in NBW infants (n?=?76; p?=?0.27), with 11.9 % of LBW and 11.8 % of NBW infants having levels <12 ng/mL (p?=?0.80). 相似文献
38.
Mridul Thakur Veena Jain Hari Parkash Pravesh Kumar 《Journal of Indian Prosthodontic Society》2012,12(3):175-181
To evaluate and compare the centric relation and horizontal condylar guidance using interocclusal wax and extra oral Gothic arch methods and subjective evaluation of dentures thus fabricated. Centric relation and horizontal condylar guidance was recorded by using interocclusal wax and gothic arch tracing in 28 completely edentulous patients. These records were transferred to the articulator and difference in both values was recorded. After that patients were divided in two groups according to the centric relation and horizontal condylar guidance recording method used to achieve balanced occlusion. Response of the dentures was subjectively evaluated using “Woelfel subjective evaluation criteria”. Centric relation recorded by both the methods did coincide in 7.14 % of patients. Centric relation recorded by interocclusal wax was posterior to Gothic centric relation in 21.43 % of patients, and anterior to Gothic centric relation in 71.42 % patients. Gothic arch tracings gave higher mean guidance values on both the sides as compared to protrusive wax record in all the subjects, although the difference was statistically insignificant (P > 0.05). Subjective evaluation showed statistical insignificance for all the parameters in both groups. Gothic arch method records the centric relation at a more posterior position than the Static method, but it does not make any difference in clinical performance of the complete denture. Horizontal condylar guidance angle was approximately similar by both the methods. 相似文献
39.
Veena Jain Vijay Prakash Mathur Kumar Abhishek Mohit Kothari 《Journal of prosthodontic research》2012,56(4):287-292
ObjectiveThe purpose of the pilot study was to determine the effect of restoring lost occlusal vertical dimension (OVD) due to attrition on maximum bite force in humans.MethodologyA total of 124 subjects in age range of 25–40 years, with moderate to severe attrition, having full complement of teeth were screened according to inclusion and exclusion criteria. After consent, occlusal vertical dimension was assessed by employing mechanical and physiological methods in the experimental group and a maxillary canine guided hard splint was fabricated for each subjects fulfilling inclusion criteria and with positive consent (78). Bite force in experimental group was measured before, immediately after delivery of splint and subsequently at an interval of four, eight, and twelve weeks. Due loss during follow up, only 50 subjects could be available for bite force recording till 12 weeks. Bite force of age, gender, height and weight matched controls with no signs of attrition was also measured for comparison.ResultsBite force of the experimental group was found to be significantly less than the matched controls (P = 0.000) initially. After delivery of splint, bite force values increased progressively till twelve weeks. However comparison of bite force values of experimental group with control group showed no significant difference at end of eight (P = 0.008) and twelve weeks (P = 0.162).ConclusionIt was concluded that maximum bite force increases with restoration of lost vertical using splint therapy. A time period of 8–12 weeks is required to restore the maximum bite force value approximately similar to matched controls. 相似文献
40.