全文获取类型
收费全文 | 32246篇 |
免费 | 2902篇 |
国内免费 | 91篇 |
专业分类
耳鼻咽喉 | 275篇 |
儿科学 | 1098篇 |
妇产科学 | 852篇 |
基础医学 | 4797篇 |
口腔科学 | 476篇 |
临床医学 | 4098篇 |
内科学 | 6709篇 |
皮肤病学 | 663篇 |
神经病学 | 3572篇 |
特种医学 | 598篇 |
外科学 | 3162篇 |
综合类 | 363篇 |
一般理论 | 38篇 |
预防医学 | 3471篇 |
眼科学 | 464篇 |
药学 | 2263篇 |
中国医学 | 51篇 |
肿瘤学 | 2289篇 |
出版年
2023年 | 257篇 |
2022年 | 420篇 |
2021年 | 881篇 |
2020年 | 603篇 |
2019年 | 906篇 |
2018年 | 950篇 |
2017年 | 722篇 |
2016年 | 765篇 |
2015年 | 853篇 |
2014年 | 1122篇 |
2013年 | 1484篇 |
2012年 | 2356篇 |
2011年 | 2353篇 |
2010年 | 1286篇 |
2009年 | 1075篇 |
2008年 | 1878篇 |
2007年 | 1980篇 |
2006年 | 1950篇 |
2005年 | 1846篇 |
2004年 | 1708篇 |
2003年 | 1535篇 |
2002年 | 1348篇 |
2001年 | 494篇 |
2000年 | 447篇 |
1999年 | 444篇 |
1998年 | 305篇 |
1997年 | 247篇 |
1996年 | 217篇 |
1995年 | 222篇 |
1994年 | 162篇 |
1993年 | 161篇 |
1992年 | 251篇 |
1991年 | 251篇 |
1990年 | 255篇 |
1989年 | 257篇 |
1988年 | 256篇 |
1987年 | 221篇 |
1986年 | 233篇 |
1985年 | 191篇 |
1984年 | 164篇 |
1983年 | 158篇 |
1982年 | 126篇 |
1981年 | 112篇 |
1980年 | 105篇 |
1979年 | 153篇 |
1978年 | 135篇 |
1976年 | 111篇 |
1974年 | 127篇 |
1973年 | 113篇 |
1971年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
The chemical, physical and biological properties of the cytolysin tenebrosin-C from Actinia tenebrosa have been compared with those of equinatoxin II from Actinia equina. The two proteins are indistinguishable by reverse-phase and cation-exchange HPLC and capillary zone electrophoresis, and give similar peptide fragments upon cyanogen bromide cleavage (as judged by the chromatographic behaviour, ultraviolet absorption spectra, amino acid composition and N-terminal amino acid sequences of the peptides). Their cardiac stimulatory activities are identical, and their haemolytic activities are similar, with equinatoxin II having slightly greater activity. These data indicate that the two molecules are either identical in all 179 amino acid positions, or differ by no more than one or two residues. These findings are discussed in the context of the taxonomic relationship between the two species of sea anemone. 相似文献
103.
104.
A. C. Webster J. C. Craig J. M. Simpson M. P. Jones J. R. Chapman 《American journal of transplantation》2007,7(9):2140-2151
Transplant recipients have increased cancer risk, but data on risk variation across different patient groups are sparse. Rates and standardized rate ratios (SRR) of cancer (all sites, excluding nonmelanocytic skin and lip cancer) compared to the general population were calculated, using Australia and New Zealand Dialysis and Transplant Registry data. Within the transplant population, risk factors were identified (hazard ratios: HR; 95% CI) and absolute risk estimated for recipient groups. A total of 1642 (10.8%) of 15 183 recipients developed cancer. Risk was inversely related to age (SRR 15-30 children, 2 if >65 years). Females aged 25-29 had rates equivalent to women aged 55-59 from the general population. Age trend for lymphoma, colorectal and breast risk was similar; melanoma showed less variability across ages, prostate showed no risk increase. Within the transplanted population, risk was affected by age differently for each sex (p = 0.007), elevated by prior malignancy (HR 1.40; 1.03-1.89), white race (HR 1.36; 1.12-1.89), but reduced by diabetic end-stage kidney disease (ESKD) (HR 0.67; 0.50-0.89). Cancer rates in kidney recipients are similar to nontransplanted people 20-30 years older, but absolute risk differs across patient groups. Men aged 45-54 surviving 10 years have cancer risks varying from 1 in 13 (non-white, no prior cancer, diabetic ESKD) to 1 in 5 (white, prior cancer, other ESKD). 相似文献
105.
P G Gibson J L Simpson 《The European respiratory journal》2004,23(3):492; author reply 492-492; author reply 493
106.
Conventional follicle harvesting techniques for hair transplantation are limited by the available scalp donor hair. The development of an innovative technique of microsurgical single follicular unit extraction has made it possible to exploit body hair grafts for scalp transplantation. This case study reports on 18 months of follow-up on a patient with extensive scalp scarring who underwent a transplantation procedure using donor chest hair. The photographically documented results show a change in the length of the chest hair measuring an average of 4 cm at transplant to 15 cm by 18 months post-transplant. The transplanted chest grafts provided an excellent cosmetic result for hair replacement. 相似文献
107.
Kazumasa Fujitani Jaffer A. Ajani Christopher H. Crane Barry W. Feig Peter W. Pisters Nora Janjan Garrett L. Walsh Stephen G. Swisher Ara A. Vaporciyan David Rice Angela Welch Jackie Baker Josephine Faust Paul F. Mansfield MD 《Annals of surgical oncology》2007,14(4):1305-1311
Background Significant tumor downstaging has been achieved in patients with localized gastric or gastroesophageal adenocarcinoma by induction
chemotherapy and preoperative chemoradiotherapy (CTX–CTXRT). However, the influence of CTX–CTXRT on operative morbidity and
mortality has not yet been clarified. The aim of the present study was to document the frequency and nature of morbidity and
mortality after surgery combined with CTX–CTXRT, and identify factors predictive of postoperative complications in patients
with localized gastric or gastroesophageal adenocarcinoma.
Methods A prospectively collected database on 71 consecutive patients who underwent CTX–CTXRT at M.D. Anderson Cancer Center between
January 1997 and August 2004 was reviewed. Postoperative morbidity and mortality were investigated, and risk factors for overall
complications were identified by multivariate logistic regression analysis.
Results Overall morbidity and mortality rates were 38.0% (27 patients) and 2.8% (2 patients), respectively. Age greater than 60 years
[relative risk 11.3 (95% confidence interval 2.50–50.6)] and body mass index (BMI) of 26 kg/m2 or above [relative risk 4.08 (95% confidence interval 1.08–15.4)] were significant risk factors for overall complications.
Conclusions CTX–CTXRT can be performed safely with an acceptable operative morbidity and a low operative mortality rate in patients with
gastric or gastroesophageal cancer, with careful consideration of added risk associated with age and obesity. 相似文献
108.
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
109.
Angela Favaro Tatiana Zanetti Elena Tenconi Daniela Degortes Andrea Ronzan Angela Veronese Paolo Santonastaso 《Eating disorders》2004,13(1):61-70
To date, few studies have examined the personality characteristics and clinical predictors of impulsive behaviors in eating disorders (ED). The aim of this work was to study the prevalence of a wide range of impulsive behaviors in a sample of 554 ED subjects and to examine the predictors of these behaviors. Subjects were diagnosed according to DSM-IV criteria as having anorexia nervosa restricting type (ANR; n = 183), anorexia nervosa binge eating/purging type (ANBP; n = 65), bulimia nervosa purging type (BNP; n = 244), and bulimia nervosa nonpurging type (BNNP; n = 62). Nine different types of impulsive behaviors were assessed in these groups. About 55% of the whole sample reported at least one type of impulsive behavior, 35% more than one, and about 13% more than three. According to findings, impulsive and multi-impulsive subjects are characterized by the presence of purging behavior and by specific temperamental features such as high levels of novelty seeking and low persistence. The prediction of impulsive behavior is further improved by considering the presence of a history of childhood abuse, maternal psychiatric morbidity, and some specific psychological symptoms such as maturity fears, perfectionism, depression, and obsessive-compulsive symptoms. The presence of impulsive behavior appears to be associated with overall higher levels of psychiatric symptomatology and eating psychopathology, thus indicating that they are an important feature to be considered in the assessment and treatment of ED. 相似文献
110.
Angela Torlopp Stephanie S Breher Jan Schlüter Thomas Brand 《Developmental dynamics》2006,235(3):691-700
The isolation of the Popeye gene family was based on its preferential expression in striated muscle tissue. Recently, a monoclonal antibody against chick Popdc1 (also known as Bves) became available and was used in this study to comparatively analyze the expression pattern of Popdc1 at both the protein and mRNA level during early chick embryogenesis. Using whole-mount immunohistochemistry, expression in the heart was first observed at Hamburger and Hamilton (HH) stage 10 in the presumptive left ventricular segment. Cardiac expression was confined to differentiated cardiac myocytes, and undifferentiated myocytes at the anterior and posterior pole showed little expression. After looping, the outer curvature myocardium showed prominent Popdc1 staining, whereas the inner curvature was unlabeled. Despite previous reports, Popdc1 protein was not detectable at any time point in the proepicardium, epicardium, or the smooth muscle layer of the coronary vessels. Whole-mount in situ hybridization using a full-length Popdc1 probe detected novel expression domains, which have not been described previously. Popdc1 mRNA was found in Hensen's node at HH stage 4, and by HH stage 5+, expression became asymmetric. In addition, Popdc1 mRNA was found in pharyngeal endoderm and in the notochordal plate. Subsequently, beginning at HH stage 9, Popdc1 mRNA expression was found in the cardiac mesoderm and expression was maintained in the heart in a pattern very similar to the one observed by antibody staining. 相似文献