全文获取类型
收费全文 | 18477篇 |
免费 | 1725篇 |
国内免费 | 88篇 |
专业分类
耳鼻咽喉 | 239篇 |
儿科学 | 554篇 |
妇产科学 | 398篇 |
基础医学 | 2248篇 |
口腔科学 | 356篇 |
临床医学 | 2484篇 |
内科学 | 3516篇 |
皮肤病学 | 216篇 |
神经病学 | 1403篇 |
特种医学 | 851篇 |
外国民族医学 | 3篇 |
外科学 | 2414篇 |
综合类 | 491篇 |
一般理论 | 9篇 |
预防医学 | 2004篇 |
眼科学 | 596篇 |
药学 | 1544篇 |
中国医学 | 13篇 |
肿瘤学 | 951篇 |
出版年
2021年 | 317篇 |
2020年 | 207篇 |
2019年 | 291篇 |
2018年 | 322篇 |
2017年 | 203篇 |
2016年 | 287篇 |
2015年 | 303篇 |
2014年 | 407篇 |
2013年 | 583篇 |
2012年 | 801篇 |
2011年 | 868篇 |
2010年 | 495篇 |
2009年 | 422篇 |
2008年 | 738篇 |
2007年 | 875篇 |
2006年 | 854篇 |
2005年 | 778篇 |
2004年 | 768篇 |
2003年 | 699篇 |
2002年 | 650篇 |
2001年 | 572篇 |
2000年 | 605篇 |
1999年 | 532篇 |
1998年 | 233篇 |
1997年 | 221篇 |
1996年 | 211篇 |
1995年 | 207篇 |
1994年 | 182篇 |
1993年 | 167篇 |
1992年 | 417篇 |
1991年 | 422篇 |
1990年 | 393篇 |
1989年 | 412篇 |
1988年 | 365篇 |
1987年 | 341篇 |
1986年 | 338篇 |
1985年 | 328篇 |
1984年 | 267篇 |
1983年 | 228篇 |
1982年 | 160篇 |
1981年 | 124篇 |
1979年 | 195篇 |
1978年 | 173篇 |
1977年 | 150篇 |
1976年 | 135篇 |
1975年 | 116篇 |
1974年 | 160篇 |
1973年 | 145篇 |
1972年 | 130篇 |
1971年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
H. Ronald Zielke Marian J. Jackson J. Tyson Tildon Stephen R. Max 《Molecular and chemical neuropathology / sponsored by the International Society for Neurochemistry and the World Federation of Neurology and research groups on neurochemistry and cerebrospinal fluid》1993,19(3):219-233
The effect of aluminum on the metabolism of glutamate and glutamine in astrocytes was studied to provide information about a possible biochemical mechanism for aluminum neurotoxicity and its potential contribution to neurodegenerative disease. Exposure of cultured rat brain astrocytes for 3–4 d to 5–7.5 mM aluminum lactate increased glutamine synthetase activity by 100–300% and diminished glutaminase activity by 50–85%. Increased glutamine synthetase enzyme activity was accompanied by an elevated level of glutamine synthetase mRNA. Alterations in glutaminase and glutamine synthetase following aluminum exposure caused increased intracellular glutamine levels, decreased intracellular glutamate levels, and increased conversion of glutamate to glutamine and the release of the latter into the extracellular space. The results of these changes may alter the availability of neurotransmitter glutamate in vivo and may be a mechanism for the aluminum neurotoxicity observed in individuals exposed to the metal during dialysis procedures and other situations. 相似文献
32.
Prognostic significance of serum cholesterol in nursing home men 总被引:2,自引:0,他引:2
D Rudman D E Mattson H S Nagraj A G Feller D L Jackson N Caindec I W Rudman 《JPEN. Journal of parenteral and enteral nutrition》1988,12(2):155-158
Serum cholesterol was measured in 129 men (average age 70.6; range 41-96) of a Veterans Administration Nursing Home, and was correlated with other items in an extensive clinical data base. Serum cholesterol was less than 150 mg/dl in 13% of the subjects, and was less than 160 mg/dl in 18%. Cholesterol greater than 280 mg/dl occurred in 8%. Serum cholesterol varied directly (p less than 0.02) with: body weight, serum albumin, serum total protein, serum sodium, ability to walk, and ability to feed oneself; and indirectly (p less than 0.02) with death rate, degree of functional dependence, and serum SGOT and LDH. Nursing home men with cholesterol less than 150 mg/dl had a death rate of 63% during the 14 months after the cholesterol analysis, compared to a death rate of 9% in men with cholesterol greater than 150 mg/dl (p less than 0.05). Death rate during the year after the analysis was 52% if cholesterol was below 160 mg/dl, compared to 7% if it was above this threshold (p less than 0.05). 相似文献
33.
Meniscal transplantation using fresh and cryopreserved allografts. An experimental study in goats. 总被引:6,自引:0,他引:6
D W Jackson C A McDevitt T M Simon S P Arnoczky E A Atwell N J Silvino 《The American journal of sports medicine》1992,20(6):644-656
A comparative study of three subgroups of meniscal transplants was undertaken in the goat model: Group 1 (autograft) involved removal and immediate reimplantation of the meniscus; Group 2, fresh meniscal allografts; and Group 3, cryopreserved (30 days) meniscal allografts. Six months after surgery, tissues were evaluated for gross degenerative changes, proteoglycan concentration (as assessed by uronic acid), water content, vascularity, histology, and cell viability. The contralateral knee served as control for all comparisons. There was no statistical difference in the amount of arthritis present and all transplants demonstrated an essentially normal peripheral vascularity compared to controls. Sections revealed reduced numbers of cells in the central portions of the transplanted menisci and these viable cells demonstrated different behavior in multiplication in tissue culture compared to contralateral controls. Grossly and microscopically, the implanted menisci differed little from the controls. The measurement of proteoglycan concentration and water content of the transplanted meniscal cartilage suggest alterations that may affect the long-term mechanical properties. The autograft specimens showed the water content was very slightly increased (3% to 6%), while the proteoglycan concentration was increased (42% in terms of uronic acid). In contrast, the water content of the fresh allograft group and the cryopreserved group was increased 12% to 24%. Proteoglycan concentration in these groups was decreased up to 56% in portions of some menisci compared to controls. Fresh and cryopreserved meniscal allografts showed peripheral healing, revascularization, cellularity, and incorporation, and grossly appeared good at 6 months in the goat model. The biochemical changes in the extracellular matrix at 6 months raises questions on the long-term function of these transplanted menisci. 相似文献
34.
35.
This exploratory study examined the family environment of ten families, each with a physically disabled adolescent and at least one non-disabled adolescent. Family members completed the Moos Family Environment Scale (FES) and discussed with the interviewer their experiences as a family. Blind and independent ratings on the FES by social workers involved in the study provided a comparison with the families' self ratings. Family ratings on the FES gave no indication of distress, but showed slightly higher than average emphasis on cohesion and achievement orientation. Social work ratings, in contrast, indicated elevated levels of conflict, achievement orientation, and control. In this report, no attempt is made to generalize these specific findings to all families with disabled adolescents. Rather, results are interpreted, in the light of findings in the recent literature, to underscore the need for better designed research and to alert professionals to the danger of imposing the prevalent dysfunctional view upon families with disabled children and adolescents. 相似文献
36.
Protective effects of cyclophosphamide, cyclosporin A and FK506 against antigen-induced lung eosinophilia in guinea-pigs. 下载免费PDF全文
A close association has been recognized between activated T cells and eosinophils in asthma, albeit circumstantial. The present study attempted to investigate this relationship in an animal model of lung eosinophilia using the new generation of T cell-selective immunosuppressants, cyclosporin A and FK506, compared with the myelotoxic immunosuppressive agent cyclophosphamide. Antigen challenge of ovalbumin-sensitized guinea-pigs resulted in a lung eosinophilia which was assessed by bronchoalveolar lavage. All three agents caused a marked suppression of lung eosinophilia at 24 h post-challenge when the compounds were administered at the time of sensitization but not when administered for 3 days before lavage. However, the lung eosinophilia at 72 h post-challenge was reduced significantly by FK506 and by cyclophosphamide, but not by cyclosporin A, when the drugs were administered for 3 days, before lavage. These results strongly suggest the involvement of T cells in antigen-induced late phase (72 h) eosinophilia in guinea-pigs but not at 24 h. The effects of cyclophosphamide were always associated with a reduction in circulating white cell counts, whereas cyclosporin A and FK506 showed no myelotoxic properties. These results suggest the potential therapeutic use of selective, non-cytotoxic immunosuppressive agents in asthma. 相似文献
37.
38.
39.
40.
W Kepron C J Jackson A H Sehon 《International archives of allergy and applied immunology》1987,82(3-4):468-470
Newborn mongrel dogs were sensitized with conjugates of ovalbumin (OA) and 2,4-dinitrophenol (OA-DNP3) in the presence of Al(OH)3 to produce high levels of anti-OA and anti-DNP IgE antibody. At 4-6 months of age, when anti-DNP and anti-OA antibody levels reached titers of 64 by passive cutaneous anaphylaxis, the dogs underwent separate inhalation and intravenous challenges with conjugates of DNP and bovine gamma globulin (DNP15-BGG) and OA. Inhalation challenge with DNP15-BGG and OA resulted in 5- and 10-fold increases in airflow resistance, respectively. Intravenous challenge with either DNP15-BGG or OA produced profound anaphylaxis with 60-80% decreases in blood pressure, cardiac output and regional blood flows in the carotid, superior mesenteric and renal arteries, and the distal aorta. Treatment of sensitized dogs with 5 doses of 20 mg of conjugates of DNP and polyvinyl alcohol (DNP2-PVA) on alternate days resulted in suppression of anti-DNP IgE antibody production; abrogation of established airway and vascular anaphylactic sensitivities; no change in regional blood flows, and no effect on sensitivities to challenge with OA. 相似文献