全文获取类型
收费全文 | 6115篇 |
免费 | 401篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 196篇 |
妇产科学 | 141篇 |
基础医学 | 1057篇 |
口腔科学 | 67篇 |
临床医学 | 686篇 |
内科学 | 1135篇 |
皮肤病学 | 188篇 |
神经病学 | 558篇 |
特种医学 | 129篇 |
外科学 | 503篇 |
综合类 | 79篇 |
一般理论 | 4篇 |
预防医学 | 780篇 |
眼科学 | 170篇 |
药学 | 318篇 |
中国医学 | 18篇 |
肿瘤学 | 475篇 |
出版年
2023年 | 52篇 |
2022年 | 64篇 |
2021年 | 155篇 |
2020年 | 86篇 |
2019年 | 120篇 |
2018年 | 154篇 |
2017年 | 122篇 |
2016年 | 147篇 |
2015年 | 160篇 |
2014年 | 217篇 |
2013年 | 323篇 |
2012年 | 404篇 |
2011年 | 488篇 |
2010年 | 262篇 |
2009年 | 244篇 |
2008年 | 424篇 |
2007年 | 371篇 |
2006年 | 396篇 |
2005年 | 428篇 |
2004年 | 349篇 |
2003年 | 340篇 |
2002年 | 299篇 |
2001年 | 58篇 |
2000年 | 49篇 |
1999年 | 44篇 |
1998年 | 60篇 |
1997年 | 51篇 |
1996年 | 44篇 |
1995年 | 41篇 |
1994年 | 39篇 |
1993年 | 46篇 |
1992年 | 35篇 |
1991年 | 29篇 |
1990年 | 30篇 |
1989年 | 24篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 14篇 |
1985年 | 23篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 23篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1976年 | 15篇 |
1975年 | 23篇 |
1974年 | 14篇 |
1973年 | 17篇 |
排序方式: 共有6532条查询结果,搜索用时 14 毫秒
71.
Singer E Pilpel S Bsat F Plevyak M Healy A Markenson G 《Obstetrics and gynecology》2007,109(5):1083-1087
OBJECTIVE: To investigate accuracy of fetal fibronectin testing to predict preterm birth in twin gestations with symptoms of preterm labor. METHODS: We reviewed charts of all patients with twin gestations who underwent fetal fibronectin testing and presented with complaints of preterm labor between January 1, 2000, and June 30, 2004. We also reviewed the charts of all singleton gestations with similar complaints that had fetal fibronectin testing between January 1, 2000, and December 31, 2001. All samples were processed using a rapid fetal fibronectin detection system. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of fetal fibronectin testing in singleton and twin gestations in predicting delivery within 14 days of testing. RESULTS: Four hundred twenty-nine singletons and 87 twins met the inclusion criteria. The birth rate before 34 weeks of gestation for singletons was 3.5% compared with the rate of twin pregnancies of 28.7%. Fetal fibronectin predicted delivery within 14 days of testing with a sensitivity, specificity, and positive and negative predictive values in singleton gestations of 82%, 90%, 17%, and 99%, respectively. In twin gestations, fetal fibronectin predicted delivery within 14 days of testing with a sensitivity, specificity, and positive and negative predictive values of 71%, 74%, 19%, and 97%, respectively. CONCLUSION: As noted in singleton pregnancies, fetal fibronectin testing in twins has a high negative predictive value. Fetal fibronectin evaluation may be a useful tool in screening twins with symptoms of preterm labor, because a negative result places these women at a low risk for delivering within 2 weeks of testing. 相似文献
72.
73.
Legler TJ Liu Z Mavrou A Finning K Hromadnikova I Galbiati S Meaney C Hultén MA Crea F Olsson ML Maddocks DG Huang D Fisher SA Sprenger-Haussels M Soussan AA van der Schoot CE 《Prenatal diagnosis》2007,27(9):824-829
OBJECTIVE: Cell free foetal DNA (cff DNA) extracted from maternal plasma is now recognized as a potential source for prenatal diagnosis but the methodology is currently not well standardized. To evaluate different manual and automated DNA extraction methods with a view to developing standards, an International Workshop was performed. METHODS: Three plasma pools from RhD-negative pregnant women, a DNA standard, real-time-PCR protocol, primers and probes for RHD were sent to 12 laboratories and also to one company (Qiagen, Hilden, Germany). In pre-tests, pool 3 showed a low cff DNA concentration, pool 1 showed a higher concentration and pool 2 an intermediate concentration. RESULTS: The QIAamp DSP Virus Kit, the High Pure PCR Template Preparation Kit, an in-house protocol using the QIAamp DNA Blood Mini Kit, the CST genomic DNA purification kit, the Magna Pure LC, the MDx, the M48, the EZ1 and an in-house protocol using magnetic beads for manual and automated extraction were the methods that were able to reliably detect foetal RHD. The best results were obtained with the QIAamp DSP Virus Kit. The QIAamp DNA Blood Mini Kit showed very comparable results in laboratories that followed the manufacturer's protocol and started with > or = 500 microL plasma. One participant using the QIAamp DNA Blood Midi Kit failed to detect reliably RHD in pool 3. CONCLUSIONS: This workshop initiated a standardization process for extraction of cff DNA in maternal plasma. The highest yield was obtained by the QIAamp DSP Virus Kit, a result that will be evaluated in more detail in future studies. 相似文献
74.
75.
Sylvia J. Gasparini Karen Tessmer Miriam Reh Stephanie Wieneke Madalena Carido Manuela Vlkner Oliver Borsch Anka Swiersy Marta Zuzic Olivier Goureau Thomas Kurth Volker Busskamp Günther Zeck Mike O. Karl Marius Ader 《The Journal of clinical investigation》2022,132(12)
Once human photoreceptors die, they do not regenerate, thus, photoreceptor transplantation has emerged as a potential treatment approach for blinding diseases. Improvements in transplant organization, donor cell maturation, and synaptic connectivity to the host will be critical in advancing this technology for use in clinical practice. Unlike the unstructured grafts of prior cell-suspension transplantations into end-stage degeneration models, we describe the extensive incorporation of induced pluripotent stem cell (iPSC) retinal organoid–derived human photoreceptors into mice with cone dysfunction. This incorporative phenotype was validated in both cone-only as well as pan-photoreceptor transplantations. Rather than forming a glial barrier, Müller cells extended throughout the graft, even forming a series of adherens junctions between mouse and human cells, reminiscent of an outer limiting membrane. Donor-host interaction appeared to promote polarization as well as the development of morphological features critical for light detection, namely the formation of inner and well-stacked outer segments oriented toward the retinal pigment epithelium. Putative synapse formation and graft function were evident at both structural and electrophysiological levels. Overall, these results show that human photoreceptors interacted readily with a partially degenerated retina. Moreover, incorporation into the host retina appeared to be beneficial to graft maturation, polarization, and function. 相似文献
76.
77.
78.
Jennifer L. Cannon Matthew H. Seabolt Ruijie Xu Anna Montmayeur Soo Hwan Suh Marta Diez-Valcarce Filemn Bucardo Sylvia Becker-Dreps Jan Vinj 《Viruses》2022,14(7)
Noroviruses are associated with one fifth of diarrheal illnesses globally and are not yet preventable with vaccines. Little is known about the effects of norovirus infection on infant gut microbiome health, which has a demonstrated role in protecting hosts from pathogens and a possible role in oral vaccine performance. In this study, we characterized infant gut microbiome changes occurring with norovirus-associated acute gastroenteritis (AGE) and the extent of recovery. Metagenomic sequencing was performed on the stools of five infants participating in a longitudinal birth cohort study conducted in León, Nicaragua. Taxonomic and functional diversities of gut microbiomes were profiled at time points before, during, and after norovirus infection. Initially, the gut microbiomes resembled those of breastfeeding infants, rich in probiotic species. When disturbed by AGE, Gammaproteobacteria dominated, particularly Pseudomonas species. Alpha diversity increased but the genes involved in carbohydrate metabolism and glycan biosynthesis decreased. After the symptoms subsided, the gut microbiomes rebounded with their taxonomic and functional communities resembling those of the pre-infection microbiomes. In this study, during disruptive norovirus-associated AGE, the gut microbiome was temporarily altered, returning to a pre-infection composition a median of 58 days later. Our study provides new insights for developing probiotic treatments and furthering our understanding of the role that episodes of AGE have in shaping the infant gut microbiome, their long-term outcomes, and implications for oral vaccine effectiveness. 相似文献
79.
van Karnebeek Clara D. Blydt-Hansen Ingrid Matthews Allison M. Avramovic Vladimir Price Magda Drogemoller Britt Shyr Casper Lee Jessica Mwenifumbo Jill Ghani Aisha Stockler Sylvia Friedman Jan M. Lehman Anna Ross Colin J. Wasserman Wyeth W. Tarailo-Graovac Maja Horvath Gabriella A. 《Neurogenetics》2021,22(4):251-262
neurogenetics - Monoamine neurotransmitter disorders present predominantly with neurologic features, including dystonic or dyskinetic cerebral palsy and movement disorders. Genetic conditions that... 相似文献
80.
Jelle Koopsen Catharina E. van Ewijk Roisin Bavalia Akke Cornelissen Sylvia M. Bruisten Floor de Gee Alvin X. Han Maarten de Jong Menno D. de Jong Marcel Jonges Norin Khawaja Fleur M.H.P.A. Koene Mariken van der Lubben Iris Mikulic Sjoerd P.H. Rebers Colin A. Russell Janke Schinkel Anja J.M. Schreijer Judith A. den Uil Matthijs R.A. Welkers Tjalling Leenstra 《Emerging infectious diseases》2022,28(5):1012
We report a severe acute respiratory syndrome coronavirus 2 superspreading event in the Netherlands after distancing rules were lifted in nightclubs, despite requiring a negative test or vaccination. This occurrence illustrates the potential for rapid dissemination of variants in largely unvaccinated populations under such conditions. We detected subsequent community transmission of this strain. 相似文献