全文获取类型
收费全文 | 30331篇 |
免费 | 763篇 |
国内免费 | 61篇 |
专业分类
耳鼻咽喉 | 112篇 |
儿科学 | 2090篇 |
妇产科学 | 823篇 |
基础医学 | 1576篇 |
口腔科学 | 504篇 |
临床医学 | 1872篇 |
内科学 | 6845篇 |
皮肤病学 | 326篇 |
神经病学 | 1066篇 |
特种医学 | 805篇 |
外科学 | 5249篇 |
综合类 | 2534篇 |
预防医学 | 4838篇 |
眼科学 | 464篇 |
药学 | 1278篇 |
8篇 | |
中国医学 | 165篇 |
肿瘤学 | 600篇 |
出版年
2023年 | 163篇 |
2022年 | 322篇 |
2021年 | 628篇 |
2020年 | 460篇 |
2019年 | 3544篇 |
2018年 | 2758篇 |
2017年 | 1286篇 |
2016年 | 299篇 |
2015年 | 338篇 |
2014年 | 1064篇 |
2013年 | 797篇 |
2012年 | 887篇 |
2011年 | 901篇 |
2010年 | 777篇 |
2009年 | 639篇 |
2008年 | 547篇 |
2007年 | 560篇 |
2006年 | 440篇 |
2005年 | 401篇 |
2004年 | 341篇 |
2003年 | 277篇 |
2002年 | 202篇 |
2001年 | 195篇 |
2000年 | 148篇 |
1999年 | 142篇 |
1998年 | 121篇 |
1997年 | 143篇 |
1996年 | 71篇 |
1995年 | 51篇 |
1994年 | 45篇 |
1993年 | 23篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1986年 | 8篇 |
1985年 | 975篇 |
1984年 | 1404篇 |
1983年 | 1051篇 |
1982年 | 1147篇 |
1981年 | 1099篇 |
1980年 | 956篇 |
1979年 | 1060篇 |
1978年 | 989篇 |
1977年 | 691篇 |
1976年 | 886篇 |
1975年 | 787篇 |
1974年 | 701篇 |
1973年 | 736篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
111.
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
112.
J W Kupiec-Weglinski E Towpik T M Schneider D Araneda L Ma N L Tilney 《Human immunology》1985,14(3):270-278
(LEW X BN)F1 cardiac allografts are rejected within 8 days in untreated LEW recipients. At the critical time point of 5 days after transplantation, the obviously rejecting grafts are enlarged and maximally infiltrated by host cells as shown by 111In-labeled lymphocyte tracer studies. However, when such hearts were retransplanted back to naive (LEW X BN)F1 secondary hosts, they survive indefinitely, showing that even late rejection is reversible in the absence of sustained host immunological drive. Attempts were then made to abrogate this advanced immune responsiveness using Cyclosporine (CsA). CsA therapy (15 mg/kg/day for 7 days) starting from day 5 produced indefinite graft survival, similar as if initiated at the time of operation. Addition of exogenous IL-2, which drives the proliferation of Tc, could not reverse this effect. Serial changes in phenotype of lymphocyte subpopulations infiltrating both acutely rejecting and indefinitely functioning cardiac allografts in unmodified and CsA treated hosts, respectively, were then studied. Ratio of Th:Tc/s cells in acutely rejecting grafts was 1.6 by day 3; it inverted abruptly to 0.7 by day 5-6, suggesting predominance of Tc/s during the later stages of allograft rejection. Similarly, treatment with CsA produced a transient depression of Th, with recovery of original Th:Tc/s ratio during the next 2-3 weeks. Adoptive transfer experiments were then performed to investigate the functional significance of these findings.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
113.
114.
W H Yang G Dorval C K Osterland N J Gilmore 《The Journal of allergy and clinical immunology》1979,63(5):300-307
Chronic immunization may lead to the production of circulating immune complexes (CICs). This study was undertaken to determine the presence of circulating IgG immune complexes in 95 subjects with allergic rhinitis/asthma receiving immunotherapy, 46 individuals with similar diagnosis but not on immunotherapy, and 64 healthy controls. Modified Raji cell and murine leukemia cell (L-1210) assays, selected for a high density of Fc receptors and devoid of Epstein-Barr virus membrane antigen, were used. Other immunological parameters such as immunologlobulins G, A, M, E, and rheumatoid factor activity were also studied. The CIC concentrations in the treated group did not differ significantly from the untreated group, although both groups did have a significantly higher concentration than the healthy controls. The presence of CICs has no relationship with age or sex of patients, dosage of allergen administered, number and nature of allergens received, period between the time of last injection and the blood sampling, and the duration of immunotherapy. Serum IgG, IgA, IgM, and rheumatoid factor activity did not differ between the treated and untreated groups. IgE was significantly higher in the treated group when compared with the untreated, and IgE levels in treated patients with elevated CICs were significantly increased compared with CIC-negative treated patients. These data suggest that CICs are present in serum of atopic diseases such as allergic rhinitis/asthma. Significantly, an association of elevation of CICs with immunotherapy could not be demonstrated. 相似文献
115.
Y Y Chua K Bremner N Lakdawalla J L Llobet H L Kokubu R P Orange C Collins-Williams 《The Journal of allergy and clinical immunology》1976,58(2):299-307
Sera of 86 patients clinically sensitive to foods were tested by passive sensitization of human and/or monkey lung (127 tests) and the radioallergosorbent test (RAST) (72 tests), using whole-food antigens; the results were compared with skin (prick) testing. Results of the prick test correlated with history in 76% of cases; lung sensitization correlated with history in 37% and with prick test in 57%; and RAST correlated with history in 54% and prick test in 72%. It is concluded that a very large percentage of adverse reactions to foods are IgE-mediated. The prick test is of use in diagnosis, particularly when combined with RAST; the lung sensitization test is technically impractical and not a reliable indicator. The best diagnostic method is careful history with food challenge and withdrawal and rechallenge; the latter is safe except in patients with a history of violent reaction. 相似文献
116.
Karyotypic evolution in Ph-positive chronic myeloid leukemia in relation to management and disease progression 总被引:1,自引:0,他引:1
Birgitta Swolin Aleksander Weinfeld Jan Westin Johan Waldenström Bengt Magnusson 《Cancer Genetics and Cytogenetics》1985,18(1):65-79
In a prospective study of 32 patients with chronic myeloid leukemia the frequency of chromosome abnormalities in addition to the Philadelphia chromosome (Ph) increased when the disease progressed. Before metamorphosis, 10 patients (31%) had developed additional abnormalities. Such abnormalities were present in three of them at the time of diagnosis; in the other seven, they were detected late in the chronic phase. New clonal abnormalities heralded or accompanied a more malignant phase of the disorder, usually a blastic leukemia. During metamorphosis, 78% of the patients had additional abnormalities, which in 68% of these cases comprised at least one of +8, +22q- or i(17q). Clones with additional abnormalities disappeared in eight cases, either spontaneously or in association with cytostatic therapy during the chronic or blastic phase. Involvement of chromosome #8, usually in the form of a trisomy, was found in 7 of 12 patients treated with busulfan, but was not found in any of the 10 hydroxyurea-treated patients, of whom 8 were splenectomized early during the chronic phase. Cells from the spleen, obtained by fine needle aspiration or splenectomy were cytogenetically examined in 18 cases during the chronic phase, but abnormalities in addition to the Ph were noted in only one patient, who was examined in the late chronic phase. The same abnormalities were present in bone marrow cells of this patient. 相似文献
117.
Genetics of human immune response to allergens 总被引:3,自引:0,他引:3
118.
The pattern of polymorphism in the C-band-positive constitutive heterochromatin of chromosomes #1, #9, and #16 was studied in fibroblasts from 23 unrelated patients with adenomatosis of the colon and rectum and in peripheral lymphocytes from 78 control persons. The parameters of the heterochromatic regions analyzed were relative size, symmetry-asymmetry within homologous chromosome pairs, and frequency of inversions. The polyposis coli patients had a significantly higher frequency (p less than 0.05) of partial and total heterochromatin inversion on chromosome #9 than the control group (37.0% compared with 21.8%). In the other parameters studied, no significant differences were found between patients and controls. 相似文献
119.
Keratin proteins and carcinoembryonic antigen in synovial sarcomas: an immunohistochemical study of 24 cases 总被引:3,自引:0,他引:3
Twenty-four synovial sarcomas were examined for the presence of keratin proteins by an indirect immunoperoxidase method with paraffin-embedded tissues. Keratin proteins were identified in 16 of 24 cases (67 per cent). Both the pseudoglandular and spindle cell areas of all eight of the biphasic synovial sarcomas and the spindle cells of eight of the 16 monophasic synovial sarcomas contained keratin proteins. In spindle cell areas, staining was observed in single cells and small cords and clusters of cells in the absence of cleft formation or other evidence of a pseudoglandular component. The predominant cytologic staining pattern in all cases was peripheral, with localization of staining to the cell membrane or adjacent areas, but diffuse and focal cytoplasmic staining patterns were also observed. No staining for keratin proteins was seen in 101 control cases, including 52 sarcomas of various types. Carcinoembryonic antigen was also identified in four of the 24 synovial sarcomas by an indirect immunoperoxidase technique. The identification of keratin proteins may be helpful in the pathologic diagnosis of synovial sarcoma, particularly the spindle cell monophasic variant. 相似文献
120.
Bronchodilator efficacy of metaproterenol sulfate aerosol therapy delivered either by canister or jet nebulizer was compared in 25 patients, 13 with severe asthma and 12 with COPD. Treatment was carried out in double-blind crossover fashion on 2 days and consisted of either metaproterenol sulfate solution 15 mg in 2.3 ml administered from a jet nebulizer or three puffs of metered-dose metaproterenol sulfate (total 1.95 mg) inhaled sequentially. FVC and FEV1 were monitored before and after therapy for 2 hr. In 13 asthmatic patients, FEV1 increased from a baseline mean of 0.83 L to 1.57 L at 2 hr after jet nebulizer therapy and increased from 0.84 L to 1.52 L after canister therapy. In 12 patients with COPD, FEV1 increased from 0.58 L to 0.78 L after jet nebulizer therapy and from 0.57 L to 0.76 L after canister therapy. FVC also increased similarly after each form of therapy. The two types of aerosol therapy were equally effective and were without side effects. Canister therapy has the advantage over jet nebulizer therapy by being convenient and cheaper. 相似文献