全文获取类型
收费全文 | 13429篇 |
免费 | 898篇 |
国内免费 | 221篇 |
专业分类
耳鼻咽喉 | 203篇 |
儿科学 | 195篇 |
妇产科学 | 141篇 |
基础医学 | 2075篇 |
口腔科学 | 369篇 |
临床医学 | 1157篇 |
内科学 | 2694篇 |
皮肤病学 | 335篇 |
神经病学 | 767篇 |
特种医学 | 902篇 |
外国民族医学 | 2篇 |
外科学 | 1926篇 |
综合类 | 163篇 |
预防医学 | 751篇 |
眼科学 | 325篇 |
药学 | 1278篇 |
1篇 | |
中国医学 | 242篇 |
肿瘤学 | 1022篇 |
出版年
2023年 | 96篇 |
2022年 | 309篇 |
2021年 | 574篇 |
2020年 | 278篇 |
2019年 | 381篇 |
2018年 | 445篇 |
2017年 | 332篇 |
2016年 | 504篇 |
2015年 | 679篇 |
2014年 | 791篇 |
2013年 | 907篇 |
2012年 | 1347篇 |
2011年 | 1192篇 |
2010年 | 663篇 |
2009年 | 565篇 |
2008年 | 796篇 |
2007年 | 656篇 |
2006年 | 641篇 |
2005年 | 546篇 |
2004年 | 486篇 |
2003年 | 448篇 |
2002年 | 360篇 |
2001年 | 250篇 |
2000年 | 223篇 |
1999年 | 191篇 |
1998年 | 99篇 |
1997年 | 67篇 |
1996年 | 53篇 |
1995年 | 48篇 |
1994年 | 35篇 |
1993年 | 35篇 |
1992年 | 44篇 |
1991年 | 52篇 |
1990年 | 32篇 |
1989年 | 34篇 |
1988年 | 36篇 |
1987年 | 33篇 |
1986年 | 33篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 30篇 |
1982年 | 19篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 24篇 |
1978年 | 13篇 |
1976年 | 11篇 |
1975年 | 12篇 |
1973年 | 10篇 |
1970年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
Suh SW Kim J Baek CH Han J Kim H 《ASAIO journal (American Society for Artificial Internal Organs : 1992)》2001,47(5):496-500
Reliable prosthetic or tissue grafts for the trachea have not, as yet, been developed for reconstruction of large, circumferential tracheal defects. Major limitations are anastomotic dehiscence and stenosis, attributed to the poor epithelialization and vascularization of the prosthetic graft. We have developed a new tracheal prosthesis that has a well vascularized and viable mucosa. The prosthesis consists of a Prolene mesh reinforced with polypropylene rings, and coated with gelatin. We lined the luminal surface of the prosthesis with transplanted autogenous oral mucosa, wrapped the prosthesis with greater omentum, and placed it in the peritoneal cavity for 2 weeks. Complete surgical resection and replacement of a segment (5 cm in length, 8 to 10 tracheal rings) of the thoracic trachea was then performed in nine adult mongrel dogs. The transplanted mucosa was well vascularized and maintained its normal histology in prereplacement analysis. Dogs with tracheal replacement regained their full activity and did not show any respiratory problems until sacrifice at 1, 2, and 6 months. After 6 months, the prostheses were completely incorporated by the host trachea in all dogs and confluent epithelialization was confirmed histologically from the upper to the lower anastomotic site of the prosthesis; furthermore, the transplanted mucosal cells had changed to ciliated columnar epithelium. 相似文献
72.
Agnieszka Hałas Hanna Baranowska Z. Policińska W. J. Jachymczyk 《Current genetics》1997,31(4):292-301
The ability of four yeast DNA polymerase mutant strains to carry out the repair of DNA treated with MMS was studied. Mutation
in DNA polymerase Rev3, as well as the already known mutation in the catalytic subunit of DNA polymerase δ, were both found
to lead to the accumulation of single-strand breaks, which indicates defective repair. A double-mutant strain carrying mutations
in DNA polymerase δ and a deletion in the REV3 gene had a complete repair defect, both at permissive (23°C) and restrictive (38°C) temperatures, which was not observed
in other pairwise combinations of tested polymerase mutants. Other polymerases are not involved in the repair of exogenous
DNA methylation damage, since neither mutation in the DNA polymerase ɛ, nor deletion in the DNA polymerase IV (β70) gene, caused defective repair. The data obtained suggest that DNA polymerases δ and Rev3p are both necessary to perform
repair synthesis in the base-excision repair of methylation damage. The results are discussed in the light of current concepts
on the role of DNA polymerase Rev3 in mutagenesis.
Received: 18 November / 10 December 1996 相似文献
73.
High prevalence of Helicobacter pylori in saliva demonstrated by a novel PCR assay. 总被引:12,自引:1,他引:12 下载免费PDF全文
C Li P R Musich T Ha D A Ferguson Jr N R Patel D S Chi E Thomas 《Journal of clinical pathology》1995,48(7):662-666
AIMS--To investigate the prevalence of Helicobacter pylori in the saliva of patients infected with this bacterium. METHODS--A novel polymerase chain reaction (PCR) assay was developed to detect H pylori in saliva and gastric biopsy specimens from patients undergoing endoscopy. RESULTS--Our PCR assay amplified a 417 base pair fragment of DNA from all 21 DNAs derived from H pylori clinical isolates but did not amplify DNA from 23 non-H pylori strains. Sixty three frozen gastric biopsy and 56 saliva specimens were tested. H pylori specific DNA was detected by PCR in all 39 culture positive biopsy specimens and was also identified from another seven biopsy specimens which were negative by culture but positive by histology. H pylori specific DNA was identified by PCR in saliva specimens from 30 (75%) of 40 patients with H pylori infection demonstrated by culture or histological examination, or both, and in three patients without H pylori infection in the stomach. CONCLUSION--The results indicate that the oral cavity harbours H pylori and may be the source of infection and transmission. 相似文献
74.
Lee BI Oh SH Woo EJ Lee SY Cho MH Kwon O Seo JK Lee JY Baek WS 《Physics in medicine and biology》2003,48(13):1971-1986
In magnetic resonance electrical impedance tomography (MREIT), we try to reconstruct a cross-sectional resistivity (or conductivity) image of a subject. When we inject a current through surface electrodes, it generates a magnetic field. Using a magnetic resonance imaging (MRI) scanner, we can obtain the induced magnetic flux density from MR phase images of the subject. We use recessed electrodes to avoid undesirable artefacts near electrodes in measuring magnetic flux densities. An MREIT image reconstruction algorithm produces cross-sectional resistivity images utilizing the measured internal magnetic flux density in addition to boundary voltage data. In order to develop such an image reconstruction algorithm, we need a three-dimensional forward solver. Given injection currents as boundary conditions, the forward solver described in this paper computes voltage and current density distributions using the finite element method (FEM). Then, it calculates the magnetic flux density within the subject using the Biot-Savart law and FEM. The performance of the forward solver is analysed and found to be enough for use in MREIT for resistivity image reconstructions and also experimental designs and validations. The forward solver may find other applications where one needs to compute voltage, current density and magnetic flux density distributions all within a volume conductor. 相似文献
75.
Should we screen for globin gene mutations in blood samples with mean corpuscular volume (MCV) greater than 80 fL in areas with a high prevalence of thalassaemia? 总被引:2,自引:0,他引:2 下载免费PDF全文
Chan LC Ma SK Chan AY Ha SY Waye JS Lau YL Chui DH 《Journal of clinical pathology》2001,54(4):317-320
AIMS: To investigate whether it is worthwhile, in areas where thalassaemia is common, to screen for globin gene mutations in subjects with a mean corpuscular volume (MCV) above 80 fL, especially in partners of known thalassaemia carriers. METHODS: Blood samples from 95 subjects with MCV between 80 and 85 fL were screened for the presence of alpha globin gene mutations and the haemoglobin (Hb) E mutation. RESULTS: Thirty four subjects harboured globin gene mutations. Of these, 31 had deletions of one alpha globin gene, one had Hb Constant Spring, and three had Hb E mutations. CONCLUSION: Based on the above figures and known prevalence rates of thalassaemia carriers, it would seem worthwhile to screen for globin gene mutations in partners of known thalassaemia carriers, regardless of MCV, to identify pregnancies at risk of Hb H disease or Hb E/beta thalassaemia. 相似文献
76.
77.
Ferrari G Neal W Jones A Olender N Ottinger J Ha R McElrath MJ Goepfert P Weinhold KJ 《Immunology letters》2001,79(1-2):37-45
We evaluated MHC-class I-restricted CTL responses induced by HIV-1 clade B-based vaccines in nine HIV-1 seronegative vaccine recipients with regard to their patterns of HLA restriction and epitope recognition. We found that seven of nine volunteers developed detectable CTL reactivities against novel epitopes within the HIV-1 Env and Gag proteins. Although four of nine subjects were HLA-A*0201, none of the cellular responses was restricted in the context of this allele. The type of responses observed in this sampling of vaccines appeared similar to those reported during primary infection and among long term non-progressors, with three out of nine subjects recognizing HLA-B27 or HLA-B17(57)-restricted epitopes. Although the majority of CTL responses were directed against novel epitopes, these effectors were still able to mediate cross-clade reactivities. 相似文献
78.
RPG1: an essential gene of Saccharomyces cerevisiae encoding a 110-kDa protein required for passage through the G1 phase 总被引:1,自引:0,他引:1
In Saccharomyces cerevisiae cells a number of genes are required for progression through, or else to pass beyond, the G1 phase. We characterized a novel gene, RPG1, which is also involved in this phase. RPG1 is an essential gene encoding a 110-kDa evolutionarily conserved protein. Elutriated or α-factor-synchronized cells of the rpg1-1 temperature-sensitive mutant were arrested in the first cell cycle when shifted to a non-permissive temperature. The cells
remained unbudded and neither grew nor duplicated DNA. rpg1-1 cells synchronized in S phase completed mitosis and arrested as unseparated G1 cells after a shift to a non-permissive temperature. Similarly, the asynchronous rpg1-1 cells accumulated in G1 at the non-permissive temperature, but mother and daughter cells did not separate. A bulk of Calcofluor-stained material
was localized in the region adjacent to the cell septum. Our data show that Rpg1p is required for passage through the G1 phase and may be involved in growth control. Data published recently indicate that Rpg1p exhibits significant sequence similarity
to a subunit of the mammalian translation initiation factor 3.
Received: 6 October 1997 / 8 November 1997 相似文献
79.
Ae Kyung Park Il-Hwan Kim Junyoung Kim Jeong-Min Kim Heui Man Kim Chae young Lee Myung-Guk Han Gi-Eun Rhie Donghyok Kwon Jeong-Gu Nam Young-Joon Park Jin Gwack Nam-Joo Lee SangHee Woo Jin Sun No Jaehee Lee Jeemin Ha JeeEun Rhee Cheon-Kwon Yoo Eun-Jin Kim 《Osong Public Health and Research Perspectives》2021,12(1):37
Since a novel beta-coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first reported in December 2019, there has been a rapid global spread of the virus. Genomic surveillance was conducted on samples isolated from infected individuals to monitor the spread of genetic variants of SARS-CoV-2 in Korea. The Korea Disease Control and Prevention Agency performed whole genome sequencing of SARS-CoV-2 in Korea for 1 year (January 2020 to January 2021). A total of 2,488 SARS-CoV-2 cases were sequenced (including 648 cases from abroad). Initially, the prevalent clades of SARS-CoV-2 were the S and V clades, however, by March 2020, GH clade was the most dominant. Only international travelers were identified as having G or GR clades, and since the first variant 501Y.V1 was identified (from a traveler from the United Kingdom on December 22nd, 2020), a total of 27 variants of 501Y.V1, 501Y.V2, and 484K.V2 have been classified (as of January 25th, 2021). The results in this study indicated that quarantining of travelers entering Korea successfully prevented dissemination of the SARS-CoV-2 variants in Korea. 相似文献
80.
Aravind Krishnan Joshua Hsu Jinny S. Ha Stephen R. Broderick Pali D. Shah Robert SD. Higgins Christian A. Merlo Errol L. Bush 《American journal of surgery》2021,221(4):731-736
PurposeWe aimed to assess the prognostic value of Neutrophil to Lymphocyte Ratio (NLR) on long-term outcomes and graft dysfunction after lung transplantation.MethodsWe retrospectively reviewed all patients receiving a lung transplant at our institution from 2011 to 2014. The primary exposure was elevated NLR at the time of transplant, defined by NLR>4. The primary outcomes were graft failure and three-year all-cause mortality. Multivariate logistic regression and Kaplan-Meier survival analysis were used to analyze outcomes.Results95 patients were included. 40 patients (42%) had an elevated NLR. Elevated NLR was associated with graft failure (OR: 4.7 [1.2–18.8], p = 0.02), and three-year mortality (OR: 5.4 [1.3–23.2], p = 0.03) on multivariate logistic regression. Patients with elevated NLR demonstrated significantly lower survival on Kaplan-Meier analysis (50% versus 74%, p = 0.02). The c-statistic for our multivariate model was 0.91.ConclusionElevated neutrophil to lymphocyte ratio is associated with poor long-term survival and graft failure after lung transplantation. 相似文献