全文获取类型
收费全文 | 3178篇 |
免费 | 292篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 20篇 |
儿科学 | 112篇 |
妇产科学 | 53篇 |
基础医学 | 400篇 |
口腔科学 | 133篇 |
临床医学 | 392篇 |
内科学 | 626篇 |
皮肤病学 | 30篇 |
神经病学 | 175篇 |
特种医学 | 148篇 |
外科学 | 260篇 |
综合类 | 132篇 |
预防医学 | 375篇 |
眼科学 | 135篇 |
药学 | 286篇 |
中国医学 | 3篇 |
肿瘤学 | 207篇 |
出版年
2021年 | 40篇 |
2020年 | 28篇 |
2019年 | 42篇 |
2018年 | 40篇 |
2016年 | 28篇 |
2015年 | 44篇 |
2014年 | 69篇 |
2013年 | 104篇 |
2012年 | 128篇 |
2011年 | 130篇 |
2010年 | 95篇 |
2009年 | 75篇 |
2008年 | 120篇 |
2007年 | 131篇 |
2006年 | 123篇 |
2005年 | 117篇 |
2004年 | 96篇 |
2003年 | 106篇 |
2002年 | 111篇 |
2001年 | 91篇 |
2000年 | 114篇 |
1999年 | 77篇 |
1998年 | 56篇 |
1997年 | 59篇 |
1996年 | 50篇 |
1995年 | 44篇 |
1994年 | 50篇 |
1993年 | 35篇 |
1992年 | 58篇 |
1991年 | 71篇 |
1990年 | 79篇 |
1989年 | 83篇 |
1988年 | 82篇 |
1987年 | 62篇 |
1986年 | 63篇 |
1985年 | 66篇 |
1984年 | 53篇 |
1983年 | 50篇 |
1982年 | 33篇 |
1981年 | 33篇 |
1980年 | 44篇 |
1979年 | 44篇 |
1978年 | 29篇 |
1977年 | 37篇 |
1974年 | 34篇 |
1973年 | 47篇 |
1972年 | 30篇 |
1970年 | 26篇 |
1969年 | 28篇 |
1968年 | 27篇 |
排序方式: 共有3487条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
The vascularity of 49 renal masses (26 malignant and 23 benign lesions) was investigated with duplex Doppler ultrasound. Doppler signals obtained at the margins of renal masses were defined as "tumor signals" when the Doppler-shifted frequency of the lesion exceeded the frequency shift in the ipsilateral main renal artery. These exceeded 2.5 kHz with a 3-MHz insonating frequency. Among the 26 renal masses that subsequently proved to be malignant, tumor signals were obtained in 15 of 18 (83%) untreated renal cell carcinomas, in three of four Wilms tumors, and in two patients with metastases to the kidney, but not in the one patient with lymphoma. None of the 23 benign renal masses demonstrated tumor signals. Tumor vascularity in malignant lesions gives rise to abnormal, high-velocity, Doppler-shifted signals that can help in the differential diagnosis of renal masses. 相似文献
26.
Biochemical, metabolic and morphological characteristics of human neutrophil activation with pepstatin A. 下载免费PDF全文
Pepstatin A, a chemotactic pentapeptide, elicited a concentration-dependent extracellular release of granule-associated beta-glucuronidase and lysozyme from, and generation of superoxide anion (O2-) by, cytochalasin B (CB)-treated human neutrophils. Prior exposure of neutrophils to pepstatin A before the addition of CB, suppressed, in a time-dependent fashion, the subsequent production of O2- and exocytotic response. The rate and amount of enzymes released and O2- generated by pepstatin A-activated neutrophils were significantly enhanced in the presence of extracellular calcium. Pepstatin A-elicited degranulation and O2- production were suppressed by the intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-(3, 4, 5-trimethoxy) benzoate hydrochloride (TMB-8). Granule exocytosis and O2- generation by pepstatin A-treated neutrophils were suppressed by the sulphydryl reagents, N-ethylmaleimide (NEM) and iodoacetic acid (IA), and by the glycolytic inhibitor, 2-deoxy-D-glucose (2-DG). Sodium cyanide was inactive. Preincubation of neutrophils with pepstatin A "desensitized' the cells to a subsequent exposure to pepstatin A or the chemotactic tripeptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Pepstatin A-induced desensitization of granule enzyme release and O2- generation appears to be stimulus-specific in that phorbol myristate acetate (PMA) was capable of eliciting normal responses from pepstatin A-pretreated cells. The morphological changes observed in pepstatin A-treated neutrophils are reminiscent of those seen in cells exposed to FMLP. 相似文献
27.
Gregory A Hale Laura C Bowman Richard J Rochester Eli Benaim Helen E Heslop Robert A Krance Edwin M Horwitz John M Cunningham Xin Tong Deo Kumar Srivastava Rupert Handgretinger Deborah P Jones 《Biology of blood and marrow transplantation》2005,11(11):912-920
Hemolytic uremic syndrome (HUS) is an uncommon but potentially life-threatening complication of hematopoietic stem cell transplantation. We retrospectively studied the medical records of 293 children who underwent allogeneic bone marrow transplantation at St. Jude Children's Research Hospital between 1992 and 1999 to describe the clinical course of and to identify risk factors for transplant-associated HUS. Conditioning regimens included cyclophosphamide, cytarabine, and total body irradiation for patients with hematologic malignancies (n = 244); patients with nonmalignant diseases (n = 49) received disease-specific regimens. Grafts from unrelated or mismatched related donors were depleted of T lymphocytes, whereas matched sibling grafts were unmanipulated. All patients received cyclosporine as prophylaxis for graft-versus-host disease. Recipients of grafts from matched siblings also received pentoxifylline or short-course methotrexate. HUS developed in 28 (9.6%) patients at a median of 171 days after transplantation. We identified older donor age (P = .029), use of antithymocyte globulin in the conditioning regimen (P = .008), and recipient CMV seronegativity (P = .011) as being associated with an increased risk of HUS. With a multiple regression analysis, the use of antithymocyte globulin (beta = .86; P = .04) and recipient cytomegalovirus seronegativity (beta = .93; P = .035) remained significant risk factors for the development of HUS. 相似文献
28.
Circulating T-cell populations during mercuric chloride-induced nephritis in the Brown Norway rat. 总被引:3,自引:0,他引:3 下载免费PDF全文
Fluorescence-activated cell sorter analysis was used to study the peripheral lymphocyte populations during mercuric chloride (HgCl2)-induced autoimmune nephritis in the Brown Norway (BN) rat. Sequential studies showed a transient loss of T cells from peripheral blood attributable to decreases in the percentage of T-helper cells. In addition, there was a decrease in the percentage of T-cytotoxic/suppressor cells prior to the appearance of circulating anti-GBM antibodies, followed by elevated levels of T-suppressor cells during down-regulation of the response. This method may allow closer inspection of the events linking changes in T-cell populations and induction and termination of an autoimmune response. 相似文献
29.
Bowman E. M.; Brown V. J.; Kertzman C.; Schwarz U.; Robinson D. L. 《Journal of neurophysiology》1993,70(1):431-443
30.
J. H. Battocletti R. E. Halbach A. Sances Jun S. J. Larson R. L. Bowman V. Kudravcev 《Medical & biological engineering & computing》1979,17(2):183-191
A new flat crossed-coil nuclear magnetic resonance (n.m.r.) detector can be used to measure flood flow at many regions of
the body, is introduced. It is compared, bothin vitro andin vivo, with the already proven cylindrical crossed-coil n.m.r. detector. Both detectors use a single high-field homogenous magnet.
A single-sideband receiver reduces the effect of transmitter leakage into the receiver coil to allow the use of a high-level
transmitter field. Preliminary application of the flat crossed-coil detector to the detection of cerebral blood flow is presented. 相似文献