全文获取类型
收费全文 | 36207篇 |
免费 | 2228篇 |
国内免费 | 163篇 |
专业分类
耳鼻咽喉 | 511篇 |
儿科学 | 864篇 |
妇产科学 | 652篇 |
基础医学 | 4320篇 |
口腔科学 | 657篇 |
临床医学 | 3505篇 |
内科学 | 8619篇 |
皮肤病学 | 455篇 |
神经病学 | 3385篇 |
特种医学 | 1474篇 |
外国民族医学 | 1篇 |
外科学 | 6293篇 |
综合类 | 223篇 |
一般理论 | 18篇 |
预防医学 | 2142篇 |
眼科学 | 477篇 |
药学 | 2059篇 |
中国医学 | 45篇 |
肿瘤学 | 2898篇 |
出版年
2024年 | 25篇 |
2023年 | 207篇 |
2022年 | 398篇 |
2021年 | 900篇 |
2020年 | 550篇 |
2019年 | 902篇 |
2018年 | 1103篇 |
2017年 | 767篇 |
2016年 | 779篇 |
2015年 | 949篇 |
2014年 | 1380篇 |
2013年 | 1864篇 |
2012年 | 2736篇 |
2011年 | 2944篇 |
2010年 | 1685篇 |
2009年 | 1611篇 |
2008年 | 2535篇 |
2007年 | 2677篇 |
2006年 | 2482篇 |
2005年 | 2398篇 |
2004年 | 2160篇 |
2003年 | 2033篇 |
2002年 | 1812篇 |
2001年 | 295篇 |
2000年 | 188篇 |
1999年 | 256篇 |
1998年 | 399篇 |
1997年 | 318篇 |
1996年 | 227篇 |
1995年 | 230篇 |
1994年 | 188篇 |
1993年 | 181篇 |
1992年 | 110篇 |
1991年 | 124篇 |
1990年 | 99篇 |
1989年 | 86篇 |
1988年 | 67篇 |
1987年 | 64篇 |
1986年 | 66篇 |
1985年 | 74篇 |
1984年 | 92篇 |
1983年 | 93篇 |
1982年 | 85篇 |
1981年 | 81篇 |
1980年 | 69篇 |
1979年 | 40篇 |
1978年 | 40篇 |
1977年 | 31篇 |
1976年 | 27篇 |
1975年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Alan J.A. McBride Gustavo M. Cerqueira Marc A. Suchard Angela N. Moreira Richard L. Zuerner Mitermayer G. Reis David A. Haake Albert I. Ko Odir A. Dellagostin 《Infection, genetics and evolution》2009,9(2):196-205
Recent serologic, immunoprotection, and pathogenesis studies identified the Lig proteins as key virulence determinants in interactions of leptospiral pathogens with the mammalian host. We examined the sequence variation and recombination patterns of ligA, ligB, and ligC among 10 pathogenic strains from five Leptospira species. All strains were found to have intact ligB genes and genetic drift accounting for most of the ligB genetic diversity observed. The ligA gene was found exclusively in L. interrogans and L. kirschneri strains, and was created from ligB by a two-step partial gene duplication process. The aminoterminal domain of LigB and the LigA paralog were essentially identical (98.5 ± 0.8% mean identity) in strains with both genes. Like ligB, ligC gene variation also followed phylogenetic patterns, suggesting an early gene duplication event. However, ligC is a pseudogene in several strains, suggesting that LigC is not essential for virulence. Two ligB genes and one ligC gene had mosaic compositions and evidence for recombination events between related Leptospira species was also found for some ligA genes. In conclusion, the results presented here indicate that Lig diversity has important ramifications for the selection of Lig polypeptides for use in diagnosis and as vaccine candidates. This sequence information will aid the identification of highly conserved regions within the Lig proteins and improve upon the performance characteristics of the Lig proteins in diagnostic assays and in subunit vaccine formulations with the potential to confer heterologous protection. 相似文献
102.
Limitations of CT during PET/CT. 总被引:1,自引:0,他引:1
Marc J Gollub Richard Hong Debra M Sarasohn Tim Akhurst 《Journal of nuclear medicine》2007,48(10):1583-1591
Our aim was to determine the diagnostic limitations of low-dose, unenhanced CT scans performed for anatomic reference and attenuation correction during PET/CT. METHODS: The Radiology Information System at our oncologic hospital was queried during the 9-mo period from July 2002 to April 2003 for patients with PET/CT scans and diagnostic enhanced CT within 2 wk of each other. One radiologist interpreted the CT portion of the PET/CT (CT(p)) unaware of the PET results and the associated enhanced diagnostic CT (CT(d)). A medical student compared this interpretation with the official report of the CT(d) and listed all discrepancies between reports. A separate radiologist compared CT(p) and CT(d) images and classified true discrepant findings as due to lack of intravenous contrast, arm-position artifact, lack of enteric contrast, low milliamperage (mA), and quality of lung images. RESULTS: Among 100 patients, the most common malignancies were lymphoma (n = 37), cancer of the colorectum (n = 31), and esophageal cancer (n = 15). Among 194 true discrepancies in which findings were missed at CT(p), causes were as follows: (a) lack of intravenous contrast (128/194, 66%), (b) arm-down artifact (17/194, 9%), (c) quality of lung images (26/194, 13%), (d) lack of enteric contrast (15/194, 8%), and (e) low mA (8/194, 4%). Discrepancies were seen most commonly in detecting lymphadenopathy and visceral metastases. CONCLUSION: Most missed findings on the unenhanced CT portion of the PET/CT scans were due to technical factors that could be altered. Discrepant findings would have led to altered management in only 2 patients, suggesting a role for limited repeat imaging to reduce radiation and use of valuable resources. 相似文献
103.
Siamak Mohammadi Giuseppe Silvaggio Nicolas Bonnet George Berberian Richard Dorent Marc Bikter Alain Pavie Iradj Gandjbakhch 《The Journal of heart and lung transplantation》2005,24(8):995-997
BACKGROUND: We have noted an unexpectedly high incidence of prostate cancer in our heart transplant recipients (HTR). METHODS: We conducted a retrospective review of patients after heart transplantation to investigate the prevalence, treatment, and outcome of prostate cancer diagnosed after systematic screening (study group). We compared them with case-matched HTR (control). RESULTS: Among 702 recipients, 15 patients had elevated prostate-specific antigen (PSA) levels. Fourteen cases of prostate cancer were diagnosed and treated. The median time between transplantation and prostate cancer diagnosis was 73 months. No patient was diagnosed in a locally advanced (>T2) or metastatic stage. Eleven patients (78.6%) received curative treatment. During follow-up (median, 44 months), 1 patient died from prostate cancer. The survival rate between the study and control groups did not differ. CONCLUSION: Routine PSA testing is recommended as a screening test for prostate cancer in patients after heart transplantation. We believe this could also result in detection of early stages of prostate cancer, thus allowing curative treatment, and achieving similar survival to other case-matched HTR with no prostate cancer. 相似文献
104.
Background. For several years, magnification has been used to separate follicular groupings from donor strips to minimize transection of hair follicles. There has been no discussion regarding the use of magnification to create recipient sites to limit transection of existing hair follicles in recipient zones.
Objective. The study was performed to evaluate the role of magnification when creating hundreds or thousands of recipient sites in patients with existing hair.
Methods. A 2× magnified polarized light-emitting diode (LED) for graft and recipient site creation (Syris Scientific, Gray, Maine) was used in 75 consecutive male and female patients. A team of four experienced surgical assistants and the author evaluated the device for graft creation, recipient site creation, and insertion of grafts.
Results. There was no perceived advantage in creating grafts or placing grafts compared with other magnification devices and traditional methods. There was less eye strain and greater ease in creating recipient sites using polarized magnification compared with traditional surgical lights and no magnification.
Conclusion. In an era of medications that slow or stop hair loss, magnification in recipient sites can reduce transection of existing hair follicles in recipient zones, leading to maximum density from a procedure. Further studies are needed to confirm the reduced transection rate of hair follicles and determine the ideal magnification. The use of magnification with LED polarized light in the recipient zone is an important new tool in hair transplant. 相似文献
Objective. The study was performed to evaluate the role of magnification when creating hundreds or thousands of recipient sites in patients with existing hair.
Methods. A 2× magnified polarized light-emitting diode (LED) for graft and recipient site creation (Syris Scientific, Gray, Maine) was used in 75 consecutive male and female patients. A team of four experienced surgical assistants and the author evaluated the device for graft creation, recipient site creation, and insertion of grafts.
Results. There was no perceived advantage in creating grafts or placing grafts compared with other magnification devices and traditional methods. There was less eye strain and greater ease in creating recipient sites using polarized magnification compared with traditional surgical lights and no magnification.
Conclusion. In an era of medications that slow or stop hair loss, magnification in recipient sites can reduce transection of existing hair follicles in recipient zones, leading to maximum density from a procedure. Further studies are needed to confirm the reduced transection rate of hair follicles and determine the ideal magnification. The use of magnification with LED polarized light in the recipient zone is an important new tool in hair transplant. 相似文献
105.
Beatriz Lara Cristian de la Roza Sara Vil�� Rafael Vidal Marc Miravitlles 《INT J CHRONIC OBSTR》2007,2(3):393-398
The Spanish registry of alpha-1 antitrypsin deficiency was founded in 1993 and became a member of the International Registry (AIR) in 1999. We describe the updating process following its incorporation into AIR and compare the data collected in the first period (1993–1999) and the second period (1999–2005), during which time patients were included exclusively by internet.The registry included 301 patients during period 1, 69% males and 46% had a history of smoking. Their mean age was 46 years (SD = 13) and 284 (94%) had the ZZ phenotype, 49% received augmentation therapy. During period 2, 161 new cases were included, 63% of whom were males with a mean age of 44 years (SD = 16). A total of 126 (78%) had the ZZ phenotype. Only 12% received augmentation therapy. A total of 462 different patients were included in both periods. Significant differences were observed in the number of cases with the SZ phenotype and the severity of FEV1 impairment between the two periods.Implementation of an internet-based collection of data did not result in a lower rate of reporting to the registry. However, data from a significant number of patient included in period 1 could not be actualized in the new data base. 相似文献
106.
Marc D Pacifico Norbert V Kang 《Journal of plastic, reconstructive & aesthetic surgery》2007,60(5):455-464
BACKGROUND: The tuberous breast presents a problem for which many surgical solutions have been described. Current teaching describes how the tuberous breast deformity is the result of skin shortage as well as herniation of breast tissue through the nipple-areola complex. However, through careful clinical observation we now believe that the only abnormality present is herniation of breast tissue through the nipple-areola complex. METHODS: Using this principle, we have refined a one-stage surgical procedure that can be used to correct any type of tuberous breast deformity. Since 2001 we have performed our technique on a series of 13 tuberous breasts of widely varying appearances in eight patients (age 17-24 years) with a follow up varying between 3 and 56 months. Our new understanding of the tuberous breast deformity has also made it possible to develop an objective, reproducible method for defining the tuberous breast based on the degree of areola herniation. RESULTS: All patients reported high levels of satisfaction with the procedure. Assessment of the results by an independent panel of attending surgeons showed all results to be good/excellent. Moreover, the results have improved with time and no revisions have been needed. Our method of defining the tuberous breast (based on the ratio of areola herniation:areola diameter) enabled us to identify a cut-off to decide (objectively) when a breast was tuberous. This allowed us to anticipate when an areola reduction/tightening procedure would be necessary to avoid a 'double-bubble' deformity. CONCLUSION: We propose a one-stage surgical procedure which is applicable to all degrees of tuberous breast deformity. The results appear to confirm our theory that the only abnormality present in the tuberous breast is herniation of breast tissue through the nipple-areola complex. In patients with small breasts and a tuberous deformity, correction of the herniation changes the tuberous breast into a simple hypoplastic breast. The volume deficit can then be corrected by augmentation (if desired by the patient). In patients with sufficient breast volume, correction of the herniation alone will correct the deformity. 相似文献
107.
Dewey Marc; Taubert Teodora; Hammerschmidt Robert; Dubel Hans-Peter 《European heart journal》2007,28(5):552
A 62-year-old man with typical angina pectoris was referredfor imaging of the coronary arteries to detect stenoses. Multislicecomputed tomography (CT) demonstrated significant 相似文献
108.
A 72-year-old man with increasing shortness of breath and atypicalangina pectoris received a chest radiograph 相似文献
109.
Estie Kruger Marc Tennant Kirrilee Smith Jacinta Peachey 《Australasian journal on ageing》2007,26(1):15-20
Objectives: The aim of this study was to assess, in a sample of older rural community‐dwelling Australians, their: oral health status, dental treatment needs, perceived barriers to access dental services and the prevalence and severity of dental anxiety. Methods: A cross‐sectional study of elderly rural Australians. Results: Eighty participants (mean age of 71.7 years) had a mean number of 0.69 (SD 1.6) decayed teeth, 15.72 (SD 13.3) missing teeth and 3.9 (SD 5.4) filled teeth. Forty‐one per cent were edentulous. Xerostomia was reported by 53% of the edentulous and 43% of the dentate. The average Corah Dental Anxiety Scale score was 8.72 (SD 3.8). Prevalence of dental anxiety was 15.6%. Two‐thirds needed dental treatment. Conclusions: Caries experience was lower than that reported in other studies. Reported barriers to use of dental services were long waiting times, lack of perceived dental need and costs. 相似文献
110.
Salom El Hage Michle Ane Jean-Luc Stigliani Maynadier Marjorie Henri Vial Genevive Baziard-Mouysset Marc Payard 《European journal of medicinal chemistry》2009,44(11):4778-4782
In this paper we describe the design and synthesis of 18 derivatives of the antimicrobial atovaquone which were substituted at the 3-hydroxy group by ester and ether functions. The compounds were evaluated in vitro for their activity against the growth of Plasmodium falciparum, the malaria causing parasite. All the compounds showed potent activity, with IC50 values in the range of 1.25–50 nM, comparable to those of atovaquone and much higher than chloroquine or quinine. 相似文献