全文获取类型
收费全文 | 14600篇 |
免费 | 899篇 |
国内免费 | 70篇 |
专业分类
耳鼻咽喉 | 71篇 |
儿科学 | 546篇 |
妇产科学 | 348篇 |
基础医学 | 2042篇 |
口腔科学 | 254篇 |
临床医学 | 1436篇 |
内科学 | 3111篇 |
皮肤病学 | 367篇 |
神经病学 | 1466篇 |
特种医学 | 311篇 |
外科学 | 1497篇 |
综合类 | 85篇 |
一般理论 | 16篇 |
预防医学 | 1203篇 |
眼科学 | 297篇 |
药学 | 990篇 |
中国医学 | 25篇 |
肿瘤学 | 1504篇 |
出版年
2024年 | 19篇 |
2023年 | 161篇 |
2022年 | 277篇 |
2021年 | 506篇 |
2020年 | 307篇 |
2019年 | 431篇 |
2018年 | 472篇 |
2017年 | 379篇 |
2016年 | 379篇 |
2015年 | 471篇 |
2014年 | 617篇 |
2013年 | 795篇 |
2012年 | 1237篇 |
2011年 | 1165篇 |
2010年 | 691篇 |
2009年 | 583篇 |
2008年 | 989篇 |
2007年 | 994篇 |
2006年 | 946篇 |
2005年 | 863篇 |
2004年 | 829篇 |
2003年 | 770篇 |
2002年 | 619篇 |
2001年 | 72篇 |
2000年 | 62篇 |
1999年 | 95篇 |
1998年 | 111篇 |
1997年 | 95篇 |
1996年 | 86篇 |
1995年 | 66篇 |
1994年 | 52篇 |
1993年 | 59篇 |
1992年 | 49篇 |
1991年 | 37篇 |
1990年 | 20篇 |
1989年 | 22篇 |
1988年 | 22篇 |
1987年 | 21篇 |
1986年 | 17篇 |
1985年 | 25篇 |
1984年 | 23篇 |
1983年 | 18篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1980年 | 15篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1972年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Carol A Mathews Caroline M Nievergelt Amin Azzam Helena Garrido Denise A Chavira Jennifer Wessel Monica Bagnarello Victor I Reus Nicholas J Schork 《American journal of medical genetics. Part B, Neuropsychiatric genetics》2007,(2):174-182
To date, only one complete genome screen for obsessive-compulsive disorder (OCD) has been published. That study identified a region of suggestive linkage (maximum lod score of 2.25) with a relatively small sample size (N = 56; 27 with OCD). Additional complete genome screens are needed to confirm this finding and identify other regions of linkage. We present the clinical characteristics and power to detect linkage of 11 multigenerational families with OCD and hoarding (N = 92; 44 with OCD), as well as heritability estimates for several quantitative traits. Families with at least two individuals with OCD were identified through probands with childhood-onset OCD. Expected lod scores were calculated for simulated genetic marker data under an additive and two dominant models assuming a dense SNP marker map. All affected individuals had an early age of onset (18 or younger). Hoarding was present in 46% of subjects. Obsessive-compulsive symptoms and hoarding were highly heritable. The maximum mean expected lod score was 3.31 for OCD and 1.39 for hoarding. We found reasonable power to detect regions of interest (lod = 2) for OCD in these families, but will need to expand our family collection to have adequate power to detect regions of interest for hoarding. 相似文献
102.
Grego E Profiti M Giammarioli M Giannino L Rutili D Woodall C Rosati S 《Clinical and diagnostic laboratory immunology》2002,9(4):828-832
The pol and gag gene fragments of small ruminant lentivirus field isolates collected in the last decade in Italy were amplified, sequenced, and analyzed. Phylogenetic analysis revealed that the majority of ovine isolates form a distinct cluster more similar to caprine lentivirus prototypes than to the visna virus prototype. These findings confirm and extend those reported by Leroux et al. (Arch. Virol., 142:1125-1137, 1997). Moreover, we observed that a variable region of Gag, included in the fragment analyzed, corresponded to one of the three major capsid antigen epitopes, which suggests that the antibody response to this epitope may be type specific. To test this hypothesis, two recombinant peptides, derived from the Icelandic prototype K1514 and this novel genotype, were expressed and used in an enzyme-linked immunosorbent assay to screen a panel of ovine and caprine sera collected from different geographical locations in Italy. Several sera reacted in a type-specific manner, indicating that in a diagnostic setting the combination of at least these two type-specific peptides is necessary to cover a wide range of infections. Additionally, these results support the hypothesis of cross-species transmission based on the phylogenetic analysis described above. This has implications for the control and eradication of small ruminant lentivirus infections. 相似文献
103.
Monica Rossi Enzo Ricci Luca Colantoni Giuliana Galluzzi Roberto Frusciante Pietro A Tonali Luciano Felicetti 《BMC medical genetics》2007,8(1):8
Background
The homologous 4q and 10q subtelomeric regions include two distinctive polymorphic arrays of 3.3 kb repeats, named D4Z4. An additional BlnI restriction site on the 10q-type sequence allows to distinguish the chromosomal origin of the repeats. Reduction in the number of D4Z4 repeats below a threshold of 10 at the 4q locus is tightly linked to Facioscapulohumeral Muscular Dystrophy (FSHD), while similar contractions at 10q locus, are not pathogenic. Sequence variations due to the presence of BlnI-sensitive repeats (10q-type) on chromosome 4 or viceversa of BlnI-resistant repeats (4q-type) on chromosome 10 are observed in both alleles. 相似文献104.
Differentiation of Cucumber mosaic virus isolates by hybridization to oligonucleotides in a microarray format 总被引:5,自引:0,他引:5
Deyong Z Willingmann P Heinze C Adam G Pfunder M Frey B Frey JE 《Journal of virological methods》2005,123(1):101-108
A system for microarrays was developed to detect and differentiate Cucumber mosaic virus (CMV) serogroups and subgroups. The coat protein genes of 14 different isolates were amplified using cy3-labelled generic but species-specific primers. These amplicons were hybridized against a set of five different serotype and subgroup specific 24-mer oligonucleotides bound to an aldehyde-coated glass slide via an aminolinker. The results of the hybridization revealed that the method allowed a clear differentiation of the 14 different CMV isolates into the serogroupes 1 and 2, and in addition was able to assign 9 out of 10 different serogroup 1 isolates correctly into subgroups 1a and 1b. This differentiation was not possible by RFLP analysis with the restriction enzyme MspI. The use of amplicons larger than 700 base pairs and their successful differentiation by hybridization to specific oligonucleotides opens avenues to highly parallel, yet sensitive assays for plant viruses. 相似文献
105.
106.
Human cancer is an unpredictable disease as is its response to therapy. The intrinsic genetic heterogeneity and instability
of cancer cells could in part explain such behavior. However, it is possible that, individual variation in the genetic make-up
of humans may affect the relationship between host and cancer cells and, therefore, be, at least in part responsible for this
extraordinary variation. Human gene polymorphism has been shown indeed to play a role in immune responses; among the immune-related
genes, cytokines are often polymorphic. Some polymorphisms of cytokine and cytokine receptor may have direct functional significance
by altering directly and indirectly the level of gene expression and/or its function; other may only demarcate a genetic linkage
to a particular haplotype associated with a given clinical condition. The majority of polymorphisms found in cytokines or
their receptors are located in the promoter, intronic and 3′ untranslated regions. These sequence variations can still affect
gene expression and function. In this review will we summarize the current knowledge about the role of cytokine polymorphism
in disease and more specifically in cancer. 相似文献
107.
Francesco Leone Giuliana Cavalloni Monica Gunetti Ymera Pignochino Wanda Piacibello Massimo Aglietta 《Biology of blood and marrow transplantation》2006,12(1):68-74
Tumor cell contamination might induce relapse after autologous transplantation in breast cancer patients. We used an ex vivo purging strategy to decrease the number of contaminating breast tumor cells in leukaphereses without altering the engraftment potential of the hemopoietic progenitor cells. This method is based on immunoselection of CD34+ cells derived from mobilized peripheral blood of patients with metastatic breast cancer and expansion in the presence of flt3 ligand, stem cell factor, interleukin 6, and thrombopoietin. Tumor contamination before and after culture was monitored by mammaglobin messenger RNA amplification by quantitative polymerase chain reaction. We analyzed both adherent and suspended cells obtained after 2 weeks of culture. Hemopoietic progenitors were increased among suspended cells. In this fraction, tumor cell contamination was decreased, whereas it increased within the adherent cell fraction. Experimental models using CD34+ cells from healthy donors spiked with breast cancer cells were also constructed to investigate whether treatment with anti-ErbB-receptor drugs could further reduce the tumor load without affecting the clonogenic potential of hemopoietic cells. For this purpose, we successfully assayed trastuzumab, a monoclonal antibody against ErbB-2, and gefitinib, an epidermal growth factor receptor tyrosine kinase receptor inhibitor. These results suggest that positively selected CD34+ cells from cancer patients contain tumor cells and that ex vivo expansion can reduce the tumor load of the suspended fraction. Target-based agents against ErbB-2, epidermal growth factor receptor, or both--such as trastuzumab or gefitinib--might increase the efficiency of purging. 相似文献
108.
A one-year follow-up on the effects of raloxifene on thyroid function in postmenopausal women 总被引:5,自引:0,他引:5
Ceresini G Morganti S Rebecchi I Bertone L Ceda GP Bacchi-Modena A Sgarabotto M Baldini M Ablondi F Valenti G Braverman LE 《Menopause (New York, N.Y.)》2004,11(2):176-179
OBJECTIVE: Estrogens increase serum thyroxine-binding globulin (TBG) and total thyroxine (TT4) concentrations. Serum free thyroxine (FT4) concentrations, however, remain normal. Raloxifene (RAL) is a selective estrogen receptor modulator used to treat postmenopausal osteoporosis. Data on the long-term effects of RAL on thyroid physiology are scanty. We evaluated the effects of RAL administration for 1 year on thyroid function in osteopenic, postmenopausal women. DESIGN: Fifty osteopenic, postmenopausal women were randomly assigned to receive either RAL (60 mg/day, n = 25) or placebo (PL, n = 25) for 1 year, in a double-blind study. Measurements of serum TBG, TT4, FT4, thyroid-stimulating hormone (TSH), thyroid hormone-binding ratio (THBR), FT4 index (FT4-I) and TT4/TBG ratio were carried out at baseline and after 4 and 12 months of therapy. RESULTS: Baseline values were similar in both treatment groups. Serum TBG concentrations were increased during RAL treatment from baseline values of 29.60 +/- 0.9 microg/mL to 31.45 +/- 1.33 and 32.34 +/- 1.37 microg/mL at 4 months and 1 year, respectively (P < 0.05, baseline v 1-year values) but were unchanged during PL treatment. A small, insignificant increase in TT4 and TSH concentrations occurred in the RAL group and no changes in the PL group. All other values were unchanged during either treatment. CONCLUSIONS: These results demonstrate that RAL significantly increased serum TBG levels, but the changes were small and not accompanied by changes in FT4-I, FT4, or TSH concentrations, suggesting that long-term RAL treatment is unlikely to clinically affect the thyroid status in euthyroid, postmenopausal women. 相似文献
109.
Sania Amr Mary E Bollinger Monica Myers Robert G Hamilton Sheila R Weiss Maura Rossman Lisette Osborne Sidey Timmins Daniel S Kimes Elissa R Levine Carol J Blaisdell 《Annals of allergy, asthma & immunology》2003,90(1):34-40
BACKGROUND: Asthma in school children is rising, and indoor allergens are very common triggers of asthma attacks; however, the risk of the school environment on asthma has not been well studied. OBJECTIVE: To determine the presence and the levels of common aeroallergens in schools, where asthma prevalence rates are high. METHODS: Settled dust samples were collected from 12 Baltimore City public elementary schools, and they were analyzed for the following allergens: cockroaches (Bla g 1/2), dust mites (Der f 1/p 1), dog (Can f 1), cat (Fel d 1), and mouse (Mus m 1). School asthma prevalence rates were correlated with allergen levels, and association between allergen levels and other risk factors present in the schools' environment was examined. RESULTS: The mean and range levels were 1.49 U/g (0 to 8) for Bla g 1/2; 0.38 microg/g (0 to 11.9) for the Der f 1/p 1; 1.44 microg/g (0.1 to 9.6) for Can f 1; 1.66 microg/g (0.2 to 12) for Fel d 1; and 6.24 microg/g (0.3 to 118.3) for Mus m 1. Dust mite, cat and dog allergens were significantly in rooms with carpet and/or area rugs, compared to rooms with bare floors (P < 0.05). Asthma prevalence rates varied from 11.8 to 20.8% between schools and positively correlation with the mean levels of Bla g 1/2 in the schools (P = 0.001). CONCLUSIONS: Common allergens that are known to trigger asthma were detected in all school environments, where asthma prevalence rates were high. However, the overall allergen levels were low, indicating that other factors, including exposures in the homes of asthmatic patients, may have more relevance to sensitization and symptoms than school exposures. 相似文献
110.
Strategic control and medial frontal negativity: beyond errors and response conflict 总被引:6,自引:0,他引:6
Errors in timed choice tasks typically produce an error-related negativity (ERN) in the event-related potential (ERP). The error specificity of the ERN has been challenged by studies showing a correct response negativity (CRN). Forty-five participants engaged in a flanker task in which both compatibility between flankers and target and the probability of compatible flankers were manipulated. Correct responses elicited a CRN, the amplitude of which increased with the degree of mismatch between the presence of conflict and conflict probability, even on low-conflict (compatible) trials. The fronto-central N2 component was larger on high-conflict (incompatible) correct response trials. However, in contrast to some recent accounts, this N2 was largest for highly probable stimuli. These findings suggest revision to models of the effects of conflict on response-related negativity to account for strategic adjustments made in preparation for the response. 相似文献