全文获取类型
收费全文 | 6824篇 |
免费 | 374篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 94篇 |
儿科学 | 647篇 |
妇产科学 | 125篇 |
基础医学 | 826篇 |
口腔科学 | 136篇 |
临床医学 | 448篇 |
内科学 | 1306篇 |
皮肤病学 | 291篇 |
神经病学 | 332篇 |
特种医学 | 243篇 |
外科学 | 686篇 |
综合类 | 187篇 |
一般理论 | 5篇 |
预防医学 | 394篇 |
眼科学 | 285篇 |
药学 | 611篇 |
中国医学 | 28篇 |
肿瘤学 | 574篇 |
出版年
2023年 | 44篇 |
2022年 | 130篇 |
2021年 | 241篇 |
2020年 | 159篇 |
2019年 | 185篇 |
2018年 | 210篇 |
2017年 | 133篇 |
2016年 | 180篇 |
2015年 | 181篇 |
2014年 | 295篇 |
2013年 | 348篇 |
2012年 | 465篇 |
2011年 | 449篇 |
2010年 | 262篇 |
2009年 | 203篇 |
2008年 | 310篇 |
2007年 | 309篇 |
2006年 | 285篇 |
2005年 | 290篇 |
2004年 | 225篇 |
2003年 | 203篇 |
2002年 | 181篇 |
2001年 | 150篇 |
2000年 | 120篇 |
1999年 | 115篇 |
1998年 | 52篇 |
1997年 | 49篇 |
1996年 | 46篇 |
1995年 | 32篇 |
1994年 | 45篇 |
1993年 | 37篇 |
1992年 | 88篇 |
1991年 | 93篇 |
1990年 | 95篇 |
1989年 | 81篇 |
1988年 | 70篇 |
1987年 | 79篇 |
1986年 | 58篇 |
1985年 | 61篇 |
1984年 | 67篇 |
1983年 | 46篇 |
1982年 | 63篇 |
1981年 | 72篇 |
1980年 | 70篇 |
1979年 | 56篇 |
1978年 | 36篇 |
1977年 | 27篇 |
1976年 | 32篇 |
1973年 | 31篇 |
1970年 | 26篇 |
排序方式: 共有7218条查询结果,搜索用时 0 毫秒
91.
Although debated, most preeminent expert panels recommend routine screening for gestational diabetes mellitus (GDM). Among
the many tests that have been used and evaluated for the screening of GDM, the fasting plasma glucose (FPG) remains very appealing.
It is easy to administer, well tolerated, inexpensive, reproducible and patient friendly. However attractive, the FPG has
given varied results in different populations and its use as a screening test for GDM remains uncertain. This review will
objectively assess the available studies to find the real value of FPG as a screening test for GDM. 相似文献
92.
93.
Chao Zhang Anurag Verma Yuanqing Feng Marcelo C. R. Melo Michael McQuillan Matthew Hansen Anastasia Lucas Joseph Park Alessia Ranciaro Simon Thompson Meagan A. Rubel Michael C. Campbell William Beggs Jibril Hirbo Sununguko Wata Mpoloka Gaonyadiwe George Mokone Regeneron Genetic Center Thomas Nyambo Dawit Wolde Meskel Gurja Belay Charles Fokunang Alfred K. Njamnshi Sabah A. Omar Scott M. Williams Daniel J. Rader Marylyn D. Ritchie Cesar de la Fuente-Nunez Giorgio Sirugo Sarah A. Tishkoff 《Proceedings of the National Academy of Sciences of the United States of America》2022,119(21)
Human genomic diversity has been shaped by both ancient and ongoing challenges from viruses. The current coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a devastating impact on population health. However, genetic diversity and evolutionary forces impacting host genes related to SARS-CoV-2 infection are not well understood. We investigated global patterns of genetic variation and signatures of natural selection at host genes relevant to SARS-CoV-2 infection (angiotensin converting enzyme 2 [ACE2], transmembrane protease serine 2 [TMPRSS2], dipeptidyl peptidase 4 [DPP4], and lymphocyte antigen 6 complex locus E [LY6E]). We analyzed data from 2,012 ethnically diverse Africans and 15,977 individuals of European and African ancestry with electronic health records and integrated with global data from the 1000 Genomes Project. At ACE2, we identified 41 nonsynonymous variants that were rare in most populations, several of which impact protein function. However, three nonsynonymous variants (rs138390800, rs147311723, and rs145437639) were common among central African hunter-gatherers from Cameroon (minor allele frequency 0.083 to 0.164) and are on haplotypes that exhibit signatures of positive selection. We identify signatures of selection impacting variation at regulatory regions influencing ACE2 expression in multiple African populations. At TMPRSS2, we identified 13 amino acid changes that are adaptive and specific to the human lineage compared with the chimpanzee genome. Genetic variants that are targets of natural selection are associated with clinical phenotypes common in patients with COVID-19. Our study provides insights into global variation at host genes related to SARS-CoV-2 infection, which have been shaped by natural selection in some populations, possibly due to prior viral infections.Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronaviruses are enveloped, positive-sense, and single-stranded RNA viruses, many of which are zoonotic pathogens that crossed over into humans. Seven coronavirus species, including SARS-CoV-2, have been discovered that, depending on the virus and host physiological condition, may cause mild or lethal respiratory disease. There is considerable variation in disease prevalence and severity across populations and communities. Importantly, minority populations in the United States appear to have been disproportionally affected by COVID-19 (1, 2). For example, in Chicago, more than 50% of COVID-19 cases and nearly 70% of COVID-19 deaths are in African Americans (who make up 30% of the population of Chicago) (1). While social and economic factors are largely responsible for driving COVID-19 health disparities, investigating genetic diversity at host genes related to SARS-CoV-2 infection could help identify functionally important variation, which may play a role in individual risk for severe COVID-19 infection.In this study, we focused on four key genes playing a role in SARS-CoV-2 infection (3). The ACE2 gene, encoding the angiotensin-converting enzyme-2 protein, was reported to be a main binding site for severe acute respiratory syndrome coronavirus (SARS-CoV) during an outbreak in 2003, and evidence showed stronger binding affinity to SARS-CoV-2, which enters the target cells via ACE2 receptors (3, 4). The ACE2 gene is located on the X chromosome (chrX); its expression level varies among populations (5); and it is ubiquitously expressed in the lung, blood vessels, gut, kidney, testis, and brain, all organs that appear to be affected as part of the COVID-19 clinical spectrum (6). SARS-CoV-2 infects cells through a membrane fusion mechanism, which in the case of SARS-CoV, is known to induce down-regulation of ACE2 (7). Such down-regulation has been shown to cause inefficient counteraction of angiotensin II effects, leading to enhanced pulmonary inflammation and intravascular coagulation (7). Additionally, altered expression of ACE2 has been associated with cardiovascular and cerebrovascular disease, which is highly relevant to COVID-19 as several cardiovascular conditions are associated with severe disease. TMPRSS2, located on the outer membrane of host target cells, binds to and cleaves ACE2, resulting in activation of spike proteins on the viral envelope and facilitating membrane fusion and endocytosis (8). Two additional genes, DPP4 and LY6E, have been shown to play an important role in the entry of SARS-CoV-2 virus into host cells. DPP4 is a known functional receptor for the Middle East respiratory syndrome coronavirus (MERS-CoV), causing a severe respiratory illness with high mortality (9, 10). LY6E encodes a glycosylphosphatidylinositol-anchored cell surface protein, which is a critical antiviral immune effector that controls coronavirus infection and pathogenesis (11). Mice lacking LY6E in hematopoietic cells were susceptible to murine coronavirus infection (11).Previous studies of genetic diversity at ACE2 and TMPRSS2 in global human populations did not include an extensive set of African populations (5, 12–14). No common coding variants (defined here as minor allele frequency [MAF] > 0.05) at ACE2 were identified in any prior population studies. However, few studies included diverse indigenous African populations whose genomes harbor the greatest diversity among humans. This leads to a substantial disparity in the representation of African ancestries in human genetic studies of COVID-19, impeding health equity as the transferability of findings based on non-African ancestries to African populations can be low (15). Including more African populations in studying the genetic diversity of genes involved in SARS-CoV-2 infection is extremely necessary. Additionally, the evolutionary forces underlying global patterns of genetic diversity at host genes related to SARS-CoV-2 infection are not well understood. Using methods to detect natural selection signatures at host genes related to viral infections helps identify putatively functional variants that could play a role in disease risk.We characterized genetic variation and studied natural selection signatures at ACE2, TMPRSS2, DPP4, and LY6E in ethnically diverse human populations by analyzing 2,012 genomes from ethnically diverse Africans (referred to as the “African diversity” dataset), 2,504 genomes from the 1000 Genomes Project (1KG), and whole-exome sequencing of 15,977 individuals of European ancestry (EA) and African ancestry from the Penn Medicine BioBank (PMBB) dataset (SI Appendix, Fig. S1). The African diversity dataset includes populations with diverse subsistence patterns (hunter-gatherers, pastoralists, agriculturalists) and speaking languages belonging to the four major language families in Africa (Khoesan; Niger–Congo, of which Bantu is the largest subfamily; Afroasiatic; and Nilo-Saharan). We identify functionally relevant variation, compare the patterns of variation across global populations, and provide insight into the evolutionary forces underlying these patterns of genetic variation. In addition, we perform an association study using the variants identified from whole-exome sequencing at the four genes and clinical traits derived from electronic health record (EHR) data linked to the subjects enrolled in the PMBB. The EHR data include diseases related to organ dysfunctions associated with severe COVID-19, such as respiratory, cardiovascular, liver, and renal complications. Our study of genetic variation in genes involved in SARS-CoV-2 infection provides data to investigate infection susceptibility within and between populations and indicates that variants in these genes may play a role in comorbidities relevant to COVID-19 severity. 相似文献
94.
Manoj Kumar Namrata Pal Poonam Sharma Manoj Kumawat Devojit Kumar Sarma Bilkees Nabi Vinod Verma Rajnarayan R. Tiwari Swasti Shubham Bahram Arjmandi Ravinder Nagpal 《Nutrients》2022,14(9)
Type-2 diabetes mellitus (T2DM) is often linked with hyperglycemia, disturbed lipid profiles, inflammation, and gut dysbiosis. Omega-3 fatty acid supplementation has a vital role in the management of T2DM. As a result, a better understanding of the potential role of omega-3 fatty acids in the development and progression of T2DM by influencing the intestinal microflora will help to improve the therapeutic intervention for T2DM and related complications. Focusing on the molecular mechanisms and signaling pathways induced by omega-3 fatty acids, this paper attempts to comprehensively review and discuss the putative associations between omega-3 fatty acids, gut dysbiosis, and the pathophysiology of T2DM and its related comorbidities. In addition, we contemplate the importance of gut microbiota in T2DM prevention and treatment and ponder the role of omega-3 fatty acids in T2DM by positively modulating gut microbiota, which may lead to discovery of novel targets and therapeutic strategies thereby paving way for further comprehensive, mechanistic, and clinical studies. 相似文献
95.
Jonathan L. Berliner Kushagra Verma Baron S. Lonner Phedra U. Penn Neil J. Bharucha 《The spine journal》2013,13(2):127-133
Background contextPrevious studies of the Scoliosis Research Society (SRS) 22 discriminative validity have lacked sufficiently matched study groups and were limited to a comparison with three or fewer subgroups of disease severity.PurposeTo evaluate the discriminative validity of SRS-22 by assessing the questionnaire's ability to discriminate among five groups of pretreatment adolescent idiopathic scoliosis (AIS) patients with increasing curve severity.Study designRetrospective review of prospectively administered surveys.MethodsTwo hundred eighty-six SRS-22 questionnaires were issued to two AIS pretreatment patient populations: 67 nonoperative and 219 preoperative. Study subjects were separated into five subgroups depending on the major Cobb angle (nonoperative 0°–19° and 20°–40° and preoperative 41°–50°, 51°–60°, and >60°). Each group (n=31) was matched for age (within 1 year) and sex (23 females and 8 males), resulting in a total of 155 study subjects. Analysis of variance was used to determine statistically significant differences (p<.05) between the five subgroups' domains and total scores.ResultsSignificant differences between study groups were found within two of the four domains (pain and image) and the total score. Both nonoperative groups (0°–19° and 20°–40°) demonstrated significantly less pain than the preoperative group (41°–50°) and significantly better self-image than all three preoperative groups. Both nonoperative groups' total scores were significantly higher than all three preoperative groups' scores, with the exception of the 20° to 40° subgroup versus the >60° subgroup. No significant differences were found between groups within the same planned treatment category.ConclusionsThe SRS-22 questionnaire demonstrated good discriminative validity between small nonoperative curves and larger surgical curves within the pain, image, and total domains. However, SRS-22 lacked the ability to differentiate between small intervals of curve magnitude, suggesting a limitation to the questionnaire's discriminative capacity. The discriminative validity of the Scoliosis Research Society (SRS) 22 has not been clearly defined. Our analysis of 155 adolescent idiopathic scoliosis patients evaluates the instrument's discriminative validity among five age- and sex-matched curve-severity subgroups. The SRS-22 questionnaire lacked the ability to differentiate between small intervals of curve magnitude, suggesting a limit to the questionnaire's discriminative capacity. 相似文献
96.
Stimulation of adrenergic activity by desipramine enhances hematopoietic stem and progenitor cell mobilization along with G‐CSF in multiple myeloma: A pilot study 下载免费PDF全文
Aditi Shastri Anjali Budhathoki Stefan K. Barta Noah Kornblum Olga Derman Ramakrishna Battini Radha Raghupathy Amit K. Verma Paul S. Frenette Ira Braunschweig Murali Janakiram 《American journal of hematology》2017,92(10):1047-1051
Hematopoietic stem cell (HSC) release is positively regulated by the sympathetic nervous system through the β3 adrenergic receptor. Preclinical studies have demonstrated that the combination of desipramine and G‐CSF resulted in improved HSC mobilization. Here, we present the results of an open‐label single‐arm pilot study in patients with multiple myeloma undergoing autologous stem cell transplantation (ASCT) to assess the safety and efficacy of desipramine combined with G‐SCF to induce HSC mobilization. The primary endpoint was safety of the combination including engraftment kinetics. The secondary endpoint was the proportion of patients who collected ≥5 × 106 CD34+ cells/kg. Outcomes were compared with historical matched controls during the same time period with multiple myeloma mobilized with G‐CSF. All study patients received desipramine 100 mg daily for 7 days, starting 4 days prior to G‐CSF administration (D‐3) and continued taking it along with G‐CSF for a total of 7 days. Six of ten patients enrolled completed the protocol with minimal side effects. All of them achieved the target collection of 5 × 106 CD34 cells/kg in a median of 1.5 apheresis session with two patients needing additional plerixafor (16%), while 11 out of 13 patients (85%) achieved the target of 5 × 106 CD34 cells/kg in the historical control group in a median of 2 apheresis procedures and seven patients needed plerixafor (54%). The combination of desipramine and G‐CSF is safe and signals improved mobilization over G‐CSF alone, providing a possible alternative means of mobilization that needs further investigation. 相似文献
97.
98.
A.A. Gupta X. Yao S. Verma H. Mackay L. Hopkins 《Clinical oncology (Royal College of Radiologists (Great Britain))》2013,25(6):346-355
The goal of this systematic review was to investigate and compare the treatment effects of systemic chemotherapy (i.e. doxorubicin, gemcitabine, gemcitabine plus docetaxel, or trabectedin) in women with inoperable, locally advanced, recurrent, or metastatic uterine leiomyosarcoma. A 2005 systematic review (searching the literature from 1980 to June 2004) on systemic therapy in advanced uterine sarcoma was used as the basis for this updated review. MEDLINE and EMBASE (from January 2004 to June 2011), the Cochrane Library, some main guideline websites and the American Society of Clinical Oncology and the Connective Tissue Oncology Society annual meeting abstracts were searched. One arm from a randomised controlled trial (RCT), four single-arm phase II trials and one abstract were included in this systematic review. The studies of gemcitabine plus docetaxel have reported numerically longer median overall survival (14.7–17.9 months versus 12.1 months) and numerically higher objective response rates (27–53% versus 25%) than those reported in the study of doxorubicin alone. The combination of gemcitabine plus docetaxel resulted in more toxicity than doxorubicin alone. The available study for single-agent gemcitabine reported a tumour response rate of 21%, which is not superior to the 25% response rate with doxorubicin alone. One abstract (pooling data from two RCTs) failed to show the superiority of gemcitabine plus docetaxel over gemcitabine alone for tumour response rate (23% versus 18%) and progression-free survival (6 versus 4.9 months). To date, there is insufficient evidence to support or refute the use of trabectedin in the target patients. Doxorubicin, gemcitabine, and gemcitabine plus docetaxel are treatment options in women with inoperable, locally advanced, recurrent, or metastatic uterine leiomyosarcoma as first- or second-line therapy. Well-designed and good-quality RCTs are required to investigate the efficacy of chemotherapy and quality of life in target patients with uterine leiomyosarcoma. 相似文献
99.
Kamlendra Singh Bhadoriya Mukesh C. Sharma Shailesh V. Jain Ganesh S. Raut Jyotsna R. Rananaware 《Medicinal chemistry research》2013,22(5):2312-2327
The discovery of clinically relevant antagonists of TRPV1 for neuropathy pain therapy has proven to be a challenging task. For better understanding of the molecular interactions of antagonists with TRPV1 receptor, a series of chroman and tetrahydroquinoline ureas were analyzed by k-nearest neighbor molecular field analysis (kNN-MFA) and molecular docking. To elucidate the structural properties required for activity as TRPV1 antagonists, we report here kNN-MFA-based 3D-QSAR model for chroman and tetrahydroquinoline ureas as potent TRPV1 antagonists. Sphere exclusion method was used for dividing the compounds into training (26 compounds) and test (5 compounds) set. Overall model classification accuracy was 81.35 % (q 2 = 0.8135, representing internal validation) in training set and 81.44 % (pred_r 2 = 0.8144, representing external validation) in test set using stepwise forward as a method of variable selection. The stereo view of molecular rectangular grid field of 3D-QSAR using this approach showed that steric and hydrophobic effects dominantly determine binding affinities. Furthermore, the crystal structure of TRPV1 was obtained from protein data bank (PDB code 2NYJ, resolution 3.20 Å), and docking of 31 TRPV1 antagonists into putative binding sites of the TRPV1 were studies. Molecular docking was employed to explore the binding mode between these compounds and the receptor, as well as help understanding the structure–activity relationship revealed by kNN-MFA. Our QSAR model and molecular docking results corroborate with each other and propose directions for the design of new antagonists with better activity toward TRPV1. 相似文献
100.