全文获取类型
收费全文 | 2787篇 |
免费 | 247篇 |
国内免费 | 12篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 106篇 |
妇产科学 | 28篇 |
基础医学 | 321篇 |
口腔科学 | 161篇 |
临床医学 | 358篇 |
内科学 | 616篇 |
皮肤病学 | 45篇 |
神经病学 | 226篇 |
特种医学 | 286篇 |
外科学 | 269篇 |
综合类 | 61篇 |
预防医学 | 173篇 |
眼科学 | 44篇 |
药学 | 226篇 |
中国医学 | 10篇 |
肿瘤学 | 100篇 |
出版年
2023年 | 15篇 |
2021年 | 32篇 |
2020年 | 29篇 |
2019年 | 35篇 |
2018年 | 52篇 |
2017年 | 32篇 |
2016年 | 39篇 |
2015年 | 52篇 |
2014年 | 66篇 |
2013年 | 86篇 |
2012年 | 104篇 |
2011年 | 92篇 |
2010年 | 93篇 |
2009年 | 98篇 |
2008年 | 96篇 |
2007年 | 107篇 |
2006年 | 102篇 |
2005年 | 95篇 |
2004年 | 85篇 |
2003年 | 101篇 |
2002年 | 82篇 |
2001年 | 85篇 |
2000年 | 72篇 |
1999年 | 74篇 |
1998年 | 72篇 |
1997年 | 72篇 |
1996年 | 76篇 |
1995年 | 68篇 |
1994年 | 64篇 |
1993年 | 68篇 |
1992年 | 52篇 |
1991年 | 63篇 |
1990年 | 49篇 |
1989年 | 88篇 |
1988年 | 65篇 |
1987年 | 65篇 |
1986年 | 70篇 |
1985年 | 57篇 |
1984年 | 49篇 |
1983年 | 38篇 |
1982年 | 31篇 |
1981年 | 33篇 |
1980年 | 27篇 |
1979年 | 29篇 |
1978年 | 24篇 |
1977年 | 27篇 |
1976年 | 20篇 |
1975年 | 22篇 |
1973年 | 17篇 |
1970年 | 12篇 |
排序方式: 共有3046条查询结果,搜索用时 62 毫秒
31.
Tumor necrosis factor-related apoptosis-inducing ligand can induce apoptosis in subsets of premalignant cells 总被引:2,自引:0,他引:2 下载免费PDF全文
Lu X Arbiser JL West J Hoedt-Miller M Sheridan A Govindarajan B Harral JW Rodman DM Fouty B 《The American journal of pathology》2004,165(5):1613-1620
During the transformation from a normal to a malignant cell, several mutations are required to bypass the pathways responsible for controlling proliferation. Premalignant cells have acquired some, but not all of these mutations and consequently have not yet attained a malignant phenotype characterized by tumor formation in vivo. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can induce apoptosis in malignant cells while sparing normal ones and is currently being considered as adjuvant therapy for various human malignancies. Whether TRAIL is effective in inducing apoptosis in premalignant cells is unclear, however. We studied the effect of TRAIL on two human premalignant cell lines the SV7tert and HA1E cells. Both cell lines had been immortalized by the addition of simian virus 40 large T antigen and the telomerase subunit hTERT, but had not been transformed into malignant cells. TRAIL initiated apoptosis by activating both the mitochondrial-independent and -dependent apoptotic pathways in both cell lines at relatively low doses whereas it had no effect on normal human pulmonary artery smooth muscle cells even at high doses. These results suggest that TRAIL can induce apoptosis in premalignant cells and suggests a novel therapy for the treatment of premalignant lesions in vivo. 相似文献
32.
Humoral immunity to commensal oral bacteria in human infants: salivary secretory immunoglobulin A antibodies reactive with Streptococcus mitis biovar 1, Streptococcus oralis, Streptococcus mutans, and Enterococcus faecalis during the first two years of life 下载免费PDF全文
Cole MF Bryan S Evans MK Pearce CL Sheridan MJ Sura PA Wientzen RL Bowden GH 《Infection and immunity》1999,67(4):1878-1886
Secretory immunoglobulin A (SIgA) antibodies reactive with the pioneer oral streptococci Streptococcus mitis biovar 1 and Streptococcus oralis, the late oral colonizer Streptococcus mutans, and the pioneer enteric bacterium Enterococcus faecalis in saliva samples from 10 human infants from birth to age 2 years were analyzed. Low levels of salivary SIgA1 and SIgA2 antibodies reactive with whole cells of all four species were detected within the first month after birth, even though S. mutans and E. faecalis were not recovered from the mouths of the infants during the study period. Although there was a fivefold increase in the concentration of SIgA between birth and age 2 years, there were no differences between the concentrations of SIgA1 and SIgA2 antibodies reactive with the four species over this time period. When the concentrations of SIgA1 and SIgA2 antibodies reactive with all four species were normalized to the concentrations of SIgA1 and SIgA2 in saliva, SIgA1 and SIgA2 antibodies reactive with these bacteria showed a significant decrease from birth to 2 years of age. Adsorption of each infant's saliva with cells of one species produced a dramatic reduction of antibodies recognizing the other three species. Sequential adsorption of saliva samples removed all SIgA antibody to the bacteria, indicating that the SIgA antibodies were directed to antigens shared by all four species. The induction by the host of a limited immune response to common antigens that are likely not involved in adherence may be among the mechanisms that commensal streptococci employ to persist in the oral cavity. 相似文献
33.
Chorneyko K Giesler R Sabatino D Ross C Lobo F Shuhaibar H Chen V Elavathil L Denardi F Ansari S Salama S LeBlanc V Norman G Sheridan B Riddell R 《American journal of clinical pathology》2002,117(5):783-790
Telepathology (TP) uses telecommunication linkages to electronically capture, store, retrieve, and transmit images to distant sites. We assessed the feasibility of a dynamic real-time TP system for light microscopic (LM) diagnosis of anatomic pathology specimens, including frozen sections. Six pathologists, in 2 separate periods, read a set of 160 retrospectively retrieved slides (80 of which were frozen sections) by TP and LM. Reading times were recorded. Diagnoses were compared with the reference diagnosis (established by a group of 5 independent pathologists) and graded on a scale of 0 to 2 (2, correct; 1, incorrect but no clinical impact; 0, incorrect with clinical impact). Overall, LM was more accurate than TP compared with the reference diagnosis (score, 1.68 vs 1.54). There was no difference in accuracy between frozen section and paraffin-embedded tissue. Intraobserver agreement ranged from 82.5% to 88.2%. The average reading time was 6.0 minutes for TP and 1.4 minutes for LM. During the study, reading time decreased for TP but not for LM. These results show that despite marginally lower accuracy and longer reading times, TP isfeasible for routine light microscopic diagnosis, including frozen sections. 相似文献
34.
Inhaled lodoxamide tromethamine in the treatment of perennial asthma: a double-blind placebo-controlled study 总被引:1,自引:0,他引:1
J S Mann P Clement A Q Sheridan I Soryal A J Fairfax S T Holgate 《The Journal of allergy and clinical immunology》1985,76(1):83-90
The efficacy of lodoxamide tromethamine in the treatment of asthma was studied in a 16-week double-blind, placebo-controlled study of 68 perennial allergic subjects with asthma. Patients received either lodoxamide tromethamine, 0.25 mg four times daily, or placebo, administered by metered-dose inhaler. Response to treatment was assessed by analyzing changes in asthma symptoms, inhaled bronchodilator requirements, and pulmonary function when compared to a 2-week baseline period. Patients treated with lodoxamide tromethamine demonstrated an improvement in daytime breathing difficulty, cough, sputum production, and sleep (p less than 0.01 to 0.05), but improvement was not significantly different from that demonstrated by placebo-treated patients. Patients from both treatment groups were able to reduce their inhaled bronchodilators (p less than 0.01), but again no significant difference was apparent between lodoxamide tromethamine and placebo treatment, nor were there any differences in peak expiratory flow rate or FEV1 between the two groups. Seven patients who received lodoxamide tromethamine withdrew because of a sensation of heat and gastrointestinal symptoms. Thus, although lodoxamide tromethamine possesses potent mast cell-stabilizing activity in vitro, we have failed to demonstrate any useful long-term effect in the treatment of mild allergic asthma. 相似文献
35.
Quantification of Human Immunodeficiency Virus Type 1 RNA Levels in Plasma by Using Small-Volume-Format Branched-DNA Assays 总被引:2,自引:0,他引:2 下载免费PDF全文
Torange Yeghiazarian Yuqi Zhao Stanley E. Read William Kabat Xiaoyi Li Sarah J. Hamren Patrick J. Sheridan Judith C. Wilber David N. Chernoff Ram Yogev 《Journal of clinical microbiology》1998,36(7):2096-2098
We have developed small-volume (50 or 250 μl)-format branched-DNA assays for human immunodeficiency virus type 1 (HIV-1) RNA for use with specimens in which the volume is limited and/or a high viral load is anticipated. These formats exhibited good correlation with the standard 1-ml format; high specificity, reproducibility, and linearity; and no significant difference in the quantification of HIV-1 subtypes. 相似文献
36.
Morphological analysis of degeneration and regeneration of syncytiotrophoblast in first trimester placental villi during organ culture 总被引:3,自引:1,他引:3
We have recently shown using dansyl-L-lysine exclusion studies that the
release of human chorionic gonadotrophin (HCG) in conjunction with L-
lactate dehydrogenase (LDH) from first trimester villi during organ culture
is symptomatic of syncytiotrophoblast degeneration. The purpose of this
study was to examine chorionic villi at the ultrastructural level in order
to determine events occurring during organ culture. The tissue was sampled
after 0, 24, 48 and 120 h in culture and processed for electron microscopy.
In addition to confirming the previously recorded syncytial degeneration,
the electron micrographs showed clearly the generation of a new
syncytiotrophoblast layer. The new layer, derived from differentiating
cytotrophoblast cells, was largely formed by 48 h and was maintained for at
least 120 h in culture. This study demonstrates a model which provides an
opportunity to study the differentiation of cytotrophoblast cells whilst
they retain their anatomical relationships within the villous structure.
相似文献
37.
38.
39.
H Nogami F Yoshimura D C Herbert T B Aufdemorte G A Gates G R Holt P J Sheridan 《The Anatomical record》1985,212(3):288-291
A quantitative autoradiographic immunocytochemical study was performed in which the nuclear uptake and retention of 3H-estradiol (3H-E2) by luteinizing hormone (LH) and prolactin (PRL) cells was examined in 19-21-year-old baboons. 3H-E2 concentrating cells were found in all of the three lobes of the pituitary in varying percentages (38.7%, pars distalis; 17.1%, pars intermedia; 6.3%, pars nervosa). Approximately 80% of PRL cells and nearly 100% of LH cells were labeled. A count of the number of silver grains over nuclei revealed a marked variation of the accumulation of 3H-E2 by LH cells and to a lesser extent in PRL cells. These results suggest functional heterogeneity among LH and PRL cells. The present results are discussed in relation to the physiological state of old animals. 相似文献
40.