全文获取类型
收费全文 | 23705篇 |
免费 | 1806篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 394篇 |
儿科学 | 814篇 |
妇产科学 | 377篇 |
基础医学 | 2431篇 |
口腔科学 | 528篇 |
临床医学 | 2168篇 |
内科学 | 5233篇 |
皮肤病学 | 550篇 |
神经病学 | 1275篇 |
特种医学 | 1107篇 |
外国民族医学 | 1篇 |
外科学 | 4545篇 |
综合类 | 329篇 |
一般理论 | 15篇 |
预防医学 | 1162篇 |
眼科学 | 824篇 |
药学 | 2040篇 |
中国医学 | 38篇 |
肿瘤学 | 1765篇 |
出版年
2023年 | 223篇 |
2022年 | 400篇 |
2021年 | 985篇 |
2020年 | 477篇 |
2019年 | 814篇 |
2018年 | 944篇 |
2017年 | 611篇 |
2016年 | 647篇 |
2015年 | 671篇 |
2014年 | 1011篇 |
2013年 | 1187篇 |
2012年 | 1739篇 |
2011年 | 1709篇 |
2010年 | 869篇 |
2009年 | 817篇 |
2008年 | 1277篇 |
2007年 | 1212篇 |
2006年 | 1123篇 |
2005年 | 981篇 |
2004年 | 883篇 |
2003年 | 749篇 |
2002年 | 645篇 |
2001年 | 587篇 |
2000年 | 550篇 |
1999年 | 489篇 |
1998年 | 166篇 |
1997年 | 138篇 |
1996年 | 140篇 |
1995年 | 145篇 |
1994年 | 114篇 |
1993年 | 100篇 |
1992年 | 268篇 |
1991年 | 284篇 |
1990年 | 248篇 |
1989年 | 214篇 |
1988年 | 212篇 |
1987年 | 219篇 |
1986年 | 194篇 |
1985年 | 177篇 |
1984年 | 111篇 |
1983年 | 127篇 |
1982年 | 85篇 |
1981年 | 70篇 |
1980年 | 59篇 |
1979年 | 129篇 |
1978年 | 77篇 |
1977年 | 69篇 |
1974年 | 65篇 |
1973年 | 88篇 |
1970年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Kyriakos Chatzopoulos Sotiris Sotiriou Andrea R. Collins Panagiotis Kartsidis Alessandra C. Schmitt Xianfeng Chen Khashayarsha Khazaie Michael L. Hinni Colleen A. Ramsower Matthew A. Zarka Samir H. Patel Joaquin J. Garcia 《Head and neck pathology》2021,15(2):509
The tumor immune microenvironment of oral tongue squamous cell carcinoma may be accountable for differences in clinical behavior, particularly between different age groups. We performed RNA expression profiling and evaluated tumor infiltrating lymphocytes (TILs) and their T-cell subsets in order to assess the functional status of oral tongue squamous cell carcinoma tumor microenvironment and detect potentially clinically useful associations. Archival surgical pathology material from sixteen oral tongue squamous cell carcinoma patients was microscopically evaluated for TIL densities. RNA was extracted from macrodissected whole tumor sections and normal controls and RNA expression profiling was performed by the NanoString PanCancer IO 360 Gene Expression Panel. Immunostains for CD4, CD8 and FOXP3 were evaluated manually and by digital image analysis. Oral tongue squamous cell carcinomas had increased TIL densities, numerically dominated by CD4 + T cells, followed by CD8 + and FOXP3 + T cells. RNA expression profiling of tumors versus normal controls showed tumor signature upregulation in inhibitory immune signaling (CTLA4, TIGIT and PD-L2), followed by inhibitory tumor mechanisms (IDO1, TGF-β, B7-H3 and PD-L1). Patients older than 44 years showed a tumor microenvironment with increased Tregs and CTLA4 expression. Immunohistochemically assessed CD8% correlated well with molecular signatures related to CD8 + cytotoxic T-cell functions. FOXP3% correlated significantly with CTLA4 upregulation. CTLA4 molecular signature could be predicted by FOXP3% assessed by immunohistochemistry (R2 = 0.619, p = 0.026). Oral tongue squamous cell carcinoma hosts a complex inhibitory immune microenvironment, partially reflected in immunohistochemically quantified CD8 + and FOXP3 + T-cell subsets. Immunohistochemistry can be a useful screening tool for detecting tumors with upregulated expression of the targetable molecule CTLA4.Electronic supplementary materialThe online version of this article (10.1007/s12105-020-01229-w) contains supplementary material, which is available to authorized users. 相似文献
102.
Sarah Wang Lina Patel Elise A. Sannar Mellad Khoshnood Natalie K. Boyd Lorena Mendez Noemi A. Spinazzi Eileen A. Quinn Michael S. Rafii Jonathan D. Santoro 《American journal of medical genetics. Part A》2023,191(7):1769-1782
Down syndrome regression disorder (DSRD) is a clinical symptom cluster of acute or subacute neurocognitive regression in otherwise health persons with Down syndrome. The objective of this study was to evaluate if adverse childhood experiences (ACEs) were more prevalent in children with DSRD than those with DS alone. A survey-based, cohort-based study was performed. Caregivers of individuals with DSRD with onset of symptoms between age 10 and 30 years and DS alone were administered the ACEs questionnaire via an online REDCap survey. A total of 159 responses were collected after excluding incomplete surveys and those not meeting criteria for DSRD. Individuals with DSRD were not more likely to experience ACEs (p = 0.18, 95% confidence interval [CI]: 0.43–1.17). In those with ACEs prior to the onset of symptoms, the median time prior was 7 months (interquartile range: 5–10). Individuals with DSRD were more likely to report three or more ACEs (52, 33%) compared to those with DS alone (39, 22%) (p = 0.02, 95% CI: 1.08–2.87). Exposure to ACEs were not predictive of response to particular therapeutic interventions although those with multiple ACEs 3 months prior to the onset of symptoms was associated with lower response rates to benzodiazepines and immunotherapy (p = 0.02, 95% CI: −3.64–−1.13). This study provides preliminary data that individuals with DSRD experience ACEs at a similar rate to individuals with only DS alone, although three or more ACEs, often preceding the onset of symptoms, was more prevalent in individuals with DSRD. 相似文献
103.
Z Shang V E Isaac H Li L Patel K M Catron T Curran G T Montelione C Abate 《Proceedings of the National Academy of Sciences of the United States of America》1994,91(18):8373-8377
This report investigates the sequence specificity requirements for homeodomain structure and DNA binding activity by the design and synthesis of a "minimAl" homeodomain (for minimalist design and alanine scanning mutagenesis) which contains the consensus residues and in which all nonconsensus residues have been replaced with alanine. The murine homeodomain Msx served as the prototype for the minimAl homeodomain, Ala-Msx. We show that Ala-Msx binds to DNA specifically, albeit with lower affinity than Msx. A derivative of the minimAl homeodomain, Ala-Msx(NT), which contains a native rather than an alanine-substituted N-terminal arm, has similar DNA binding affinity as Msx. We show that the native N-terminal arm stabilizes the tertiary structure of the minimAl homeodomain. Although Ala-Msx resembles a molten-globule protein, the structure of Ala-Msx(NT) is similar to Msx. The requirement for an intact N-terminal arm is not unique to the minimAl homeodomain, since the N-terminal arm also promotes high-affinity binding activity and appropriate tertiary structure of Msx. Therefore, the homeodomain "scaffold" consists of consensus residues, which are sufficient for DNA recognition, and nonconsensus residues in the N-terminal arm, which are required for optimal DNA binding affinity and appropriate tertiary structure. MinimAl design provides a powerful strategy to probe homeodomain structure and function. This approach should be of general utility to study the sequence specificity requirements for structure and function of other DNA-binding domains. 相似文献
104.
Serum FSH, LH, prolactin and plasma estradiol, progesterone, testosterone, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) were estimated by RIA method in male patients with tongue cancer (N=110) and in healthy age-matched male controls (N=25). In this retrospective study, there was a trend towards higher levels of FSH (P<0.01), LH (P<0.01), prolactin (P<0.001), estradiol (P<0.0001), progesterone (P<0.0001) and DHEA (P<0.01) with concomitant lower levels of testosterone (P<0.001) and DHEA-S (P<0.02) in patients with tongue cancer compared to controls. We did not find significant difference in hormone levels when grouped according to the site of the tumor and stage of the disease. Patients below 40 years of age had significantly higher levels of DHEA and DHEA-S and lower levels of FSH than their counterparts. We observed a decreased ratio of testosterone: estradiol and increased levels of FSH, LH and prolactin in tongue cancer patients. These hormonal abnormalities clearly suggest a disturbance in the pituitary-adrenal-testicular axis. Based on our previous work and from these results, we suggest that prolactin might be playing an important role in the development and progression of tongue cancer. 相似文献
105.
Bhatavdekar J Patel D Trivedi C Dave R Nadkarni S Karelia N Vora H Ghosh M Patel S Suthar T Doctor S Balar D 《Oncology reports》1994,1(1):255-257
Hormones are believed to play a dominant role as promoters in the growth and development of hormone-dependent cancers. Much less is known about the circulating hormones in male patients with oesophageal cancer. This lack of attention led us to evaluate the role of peptide and steroid hormones (by RIA) in male patients with oesophageal cancer (n=49). Blood samples of patients were collected pretherapeutically and data was compared with age matched controls (n=25). In this retrospective study, significantly high levels of FSH (P<0.02), LH (P<0.001) and prolactin (P<0.001) were observed with concomitant low levels of estradiol (P<0.001), DHEA-S (P<0.02) and testosterone (P<0.001) in patients when compared with respective controls. The patients when grouped according to anatomical site and histological type of the tumor, intergroup variation was not observed in these hormones. From our, study, it seems that hormonal imbalance or altered ratio of peptide and steroid hormones might be playing a significant role in the development and/or progression of oesophageal carcinoma in men. 相似文献
106.
Summary RSV infection continues to be a major cause of morbidity and mortality throughout the world. Despite advances in the understanding
of its pathogenesis, limited progress has been made in prevention and treatment of RSV infection. Based on the experiences
thus far it seems that control of RSV infection will be a difficult and complex task. 相似文献
107.
Raval RC Bilimoria FE Patel HA 《Indian journal of dermatology, venereology and leprology》1995,61(3):137-139
Fifty cases with chronic idiopathic urticaria of more than 3 months duration were selected and divided into two groups. Group 'A' was given 10 mg loratadine once daily, while group 'B' was given pheniramine maleate 25 mg, twice daily for one month. All patients were followed for one month more. 48% excellent response was observed in group 'A' while 16% excellent response was observed in group 'B'. Good response was observed in 24% of patients in group 'A', while in group 'B' 16% of patients had good response. No side effects were observed in loratadine group, while drowsiness was observed in pheniramine group. 相似文献
108.
Water-suppression MRI: role in the evaluation of osseous lesions 总被引:1,自引:0,他引:1
Wolansky LJ Rajaraman V Lum C Park K Fiorito TF Patel S Liu WC Wedmid A 《Clinical imaging》1999,23(5):319-326
The efficacy of chemical shift based water-suppression MRI in the evaluation of bone marrow lesions has not been previously reported. T1-weighted images without and with water suppression were compared in five patients with 16 lesions. There was a significant improvement in the contrast-to-noise ratio (from 4.32 to 5.95, P < 0.01) and contrast ratio (from 1.71 to 5.69, P < 0.004) with water suppression. Water suppression may be useful clinically by increasing the conspicuity of bone marrow lesions. 相似文献
109.
110.
An Unexpected Change in DXA Calibration not Detected by Routine Quality Control Checks 总被引:2,自引:0,他引:2
G. M. Blake N. G. Preston R. Patel R. J. M. Herd I. Fogelman 《Osteoporosis international》1999,9(2):115-120
Since its commercial introduction a decade ago, the technique of dual-energy X-ray absorptiometry (DXA) has been widely recognized
as a useful and sensitive method of measuring changes in bone mineral density (BMD) at selected sites in the skeleton such
as the spine and proximal femur. Because of their high precision and stable calibration, DXA scanners are frequently used
in clinical trials to evaluate new treatments for osteoporosis. Quality assurance procedures based on regular scanning of
phantoms are widely adopted in such trials, and continuity of the phantom BMD measurements is generally believed to ensure
continuity in the in-vivo calibration. We report a change in calibration of a DXA scanner that occurred during a clinical
trial where the calibration shift was different for the spine and femur sites and was not predicted or explained by the standard
quality control procedures using phantoms. However, we show that provided patients enrolled in studies are thoroughly randomized
and the statistical analysis is confined to the differences between the treated and control groups, then the effects of such
calibration shifts on conclusions regarding the efficacy of treatment are considerably smaller than the random statistical
errors.
Received: 12 February 1998 / Accepted: 20 May 1998 相似文献