全文获取类型
收费全文 | 1420篇 |
免费 | 72篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 71篇 |
妇产科学 | 31篇 |
基础医学 | 151篇 |
口腔科学 | 46篇 |
临床医学 | 107篇 |
内科学 | 330篇 |
皮肤病学 | 24篇 |
神经病学 | 39篇 |
特种医学 | 420篇 |
外科学 | 85篇 |
综合类 | 39篇 |
预防医学 | 32篇 |
眼科学 | 7篇 |
药学 | 72篇 |
1篇 | |
肿瘤学 | 32篇 |
出版年
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 13篇 |
2014年 | 30篇 |
2013年 | 32篇 |
2012年 | 18篇 |
2011年 | 23篇 |
2010年 | 35篇 |
2009年 | 51篇 |
2008年 | 21篇 |
2007年 | 41篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 22篇 |
2003年 | 20篇 |
2002年 | 11篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 18篇 |
1998年 | 81篇 |
1997年 | 82篇 |
1996年 | 84篇 |
1995年 | 67篇 |
1994年 | 39篇 |
1993年 | 60篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 28篇 |
1989年 | 55篇 |
1988年 | 43篇 |
1987年 | 49篇 |
1986年 | 53篇 |
1985年 | 71篇 |
1984年 | 40篇 |
1983年 | 29篇 |
1982年 | 30篇 |
1981年 | 32篇 |
1980年 | 40篇 |
1979年 | 8篇 |
1978年 | 20篇 |
1977年 | 24篇 |
1976年 | 24篇 |
1975年 | 21篇 |
1971年 | 4篇 |
排序方式: 共有1496条查询结果,搜索用时 0 毫秒
41.
M D Ullman R F Ventura L J Draski R A Deitrich R C Baker 《Alcoholism, clinical and experimental research》1992,16(5):857-862
A galactose oxidase/NaB[3H]4 technique was used to examine the relative surface exposure of gangliosides from whole brain synaptosomes of long-sleep (LS) and short-sleep (SS) mice. The surface exposure of the monosialoganglioside, GM1, did not differ between the two lines. Surface exposure of the polysialogangliosides GD1a, GD1b, and GT1b, however, was significantly greater in LS synaptosomes than in SS. Hydrolysis of the polysialogangliosides by neuraminidase to the end-product, GM1, at early time periods occurred more rapidly in LS than in SS synaptosomes. Upon exposure to either 250 mM or 50 mM ethanol, LS synaptosomal ganglioside surface exposure was decreased, but that of SS was increased. Pairwise comparisons of the individual ganglioside classes indicated that the decrease in LS synaptosomal ganglioside surface exposure was attributable to decreases in the polysialogangliosides, compared with controls. The ethanol-induced increase in SS synaptosomal ganglioside surface exposure, however, was mainly due to an increased surface exposure of only GD1a. These results suggest that intrinsic differences in the surface exposure of gangliosides and/or the magnitude and direction of ethanol-induced changes in ganglioside surface distribution may reflect biophysical or modulatory mechanisms by which this class of compounds modifies membrane sensitivity to ethanol. These results suggest that further studies should be performed to determine whether gangliosides are factors in genetically determined sensitivity to ethanol. 相似文献
42.
Primary tumor cells of myeloma patients induce interleukin-6 secretion in long-term bone marrow cultures 总被引:6,自引:9,他引:6
Lokhorst HM; Lamme T; de Smet M; Klein S; de Weger RA; van Oers R; Bloem AC 《Blood》1994,84(7):2269-2277
Long-term bone marrow cultures (LTBMC) from patients with multiple myeloma (MM) and normal donors were analyzed for immunophenotype and cytokine production. Both LTBMC adherent cells from myeloma and normal donor origin expressed CD10, CD13, the adhesion molecules CD44, CD54, vascular cell adhesion molecule 1, very late antigen 2 (VLA-2), and VLA- 5, and were positive for extracellular matrix components fibronectin, laminin, and collagen types 3 and 4. LTBMC from myeloma patients and normal donors spontaneously secreted interleukin-6 (IL-6). However, levels of IL-6 correlated with the stage of disease; highest levels of IL-6 were found in LTBMC from patients with active myeloma. To identify the origin of IL-6 production, LTBMC from MM patients and normal donors were cocultured with BM-derived myeloma cells and cells from myeloma cell lines. IL-6 was induced by plasma cell lines that adhered to LTBMC such as ARH-77 and RPMI-8226, but not by nonadhering cell lines U266 and FRAVEL. Myeloma cells strongly stimulated IL-6 secretion in cocultures with LTBMC adherent cells from normal donors and myeloma patients. When direct cellular contact between LTBMC and plasma cells was prevented by tissue-culture inserts, no IL-6 production was induced. This implies that intimate cell-cell contact is a prerequisite for IL-6 induction. Binding of purified myeloma cells to LTBMC adherent cells was partly inhibited by monoclonal antibodies against adhesion molecules VLA-4, CD44, and lymphocyte function-associated antigen 1 (LFA-1) present on the plasma cell. Antibodies against VLA-4, CD29, and LFA-1 also inhibited the induced IL-6 secretion in plasma cell-LTBMC cocultures. In situ hybridization studies performed before and after coculture with plasma cells indicated that LTBMC adherent cells produce the IL-6. These results suggest that the high levels of IL-6 found in LTBMC of MM patients with active disease are a reflection of their previous contact with tumor cells in vivo. These results provide a new perspective on tumor growth in MM and emphasize the importance of plasma cell-LTBMC interaction in the pathophysiology of MM. 相似文献
43.
High-dose etoposide and cyclophosphamide without bone marrow transplantation for resistant hematologic malignancy 总被引:2,自引:1,他引:2
Brown RA; Herzig RH; Wolff SN; Frei-Lahr D; Pineiro L; Bolwell BJ; Lowder JN; Harden EA; Hande KR; Herzig GP 《Blood》1990,76(3):473-479
Seventy-five patients with resistant acute leukemia or lymphoma received high-dose cyclophosphamide and etoposide to explore the activity of this combination in resistant hematologic malignancies, and to determine the maximum doses of these drugs that can be combined without bone marrow transplantation. Etoposide was administered over 29 to 69 hours by continuous infusion corresponding to total doses of 1.8 g/m2 to 4.8 g/m2. Cyclophosphamide, 50 mg/kg/d, was administered on 3 or 4 consecutive days total 150 to 200 mg/kg ideal body weight). At all dose levels myelosuppression was severe but reversible. Mucosal toxicity was dose-limiting with the maximum tolerated dose level combining etoposide 4.2 g/m2 with cyclophosphamide 200 mg/kg. Continuous etoposide infusion produced stable plasma levels that were lower than would be achieved after administration by short intravenous infusion, and this could explain our ability to escalate etoposide above the previously reported maximum tolerated dose. There were 28 complete (35%) and 12 partial (16%) responses. Median duration of complete response (CR) was 3.5 months (range 1.1 to 20+). Seventeen of 40 patients (42%) with acute myelogenous leukemia (AML) achieved CR, including 6 of 20 (30%) with high-dose cytosine arabinoside resistance. We conclude that bone marrow transplantation is not required after maximum tolerated doses of etoposide and cyclophosphamide. This regimen is active in resistant hematologic neoplasms, and the occurrence of CR in patients with high-dose cytosine arabinoside-resistant AML indicates a lack of complete cross-resistance between these regimens. 相似文献
44.
45.
The effect of acute exercise on high density lipoprotein-cholesterol and the subfractions in females 总被引:1,自引:0,他引:1
The effect of an acute exercise session on high density lipoprotein-cholesterol (HDL-C) and the subfractions HDL2-C and HDL3-C was determined for 9 healthy females (VO2max = 46.62 +/- 4.82 ml X kg-1 min-1). Each subject underwent a continuous 40-min run on a treadmill at a workload corresponding to 70% of VO2max. A venous blood sample was obtained immediately prior to exercise and 5 min, 24, 48 and 96 h after the exercise. Pre-exercise values were: HDL-C (61.7 +/- 3.7 mg X dl-1); HDL2-C (22.4 +/- 2.1 mg X dl-1); HDL3-C (39.3 +/- 2.0 mg X dl-1). At 5 min after exercise, HDL-C (66.2 +/- 4.4 mg X dl-1) and HDL3-C (44.5 +/- 2.8 mg X dl-1) were significantly elevated (P less than 0.01) when compared to pre-exercise values. HDL-C and HDL3-C were not significantly different from pre-exercise at the remaining time points. In comparison with pre-exercise, HDL2-C showed no significant change at any of the post-exercise time points. Results indicated that the rise in HDL-C following acute exercise was due to an increase in the subfraction HDL3-C. The change in total HDL-C and HDL3-C was transient in that pre-exercise values were re-attained within 24 h following acute submaximal exercise. 相似文献
46.
Early changes in phosphatidylcholine metabolism in human acute promyelocytic leukemia cells stimulated to differentiate by phorbol ester 总被引:7,自引:0,他引:7
The HL-60 leukemia cell line derived from a human acute promyelocytic leukemia is stimulated to differentiate into macrophages within 24-28 hr after exposure to the phorbol ester, 12-O-tetradecanoylphorbol-13- acetate (TPA). We studied early alterations (within 90 min of exposure to TPA) in phosphatidylcholine metabolism in HL-60 cells and found that phosphatidylcholine synthesis by methylation is phosphatidylethanolamine was inhibited in a dose-dependent fashion. In contrast, synthesis of phosphatidylcholine from endogenous choline was enhanced and correlated inversely with the degree of inhibition of the methylation pathway. Phorbol ester congeners of TPA caused similar alterations in phosphatidylcholine metabolism in direct relationship to their capacity to induce differentiation in HL-60 cells. Perturbation of phosphatidylcholine metabolism is an early membrane even in TPA- induced HL-60 cell differentiation. 相似文献
47.
NA Hanchard DR Murdock PL Magoulas M Bainbridge D Muzny YQ Wu M Wang AL McGuire JR Lupski RA Gibbs CW Brown 《Clinical genetics》2013,83(5):457-461
The advent of whole‐exome next‐generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½‐year old female patient with a 2‐year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work‐up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di‐deoxy sequencing. WES revealed a de novo non‐synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future. 相似文献
48.
49.
An alternative extrinsic pathway of human blood coagulation 总被引:7,自引:0,他引:7
To study the interrelationships of the major human coagulation pathways, factor X activation in normal and various deficient human plasmas was evaluated when clotting was triggered by dilute rabbit or human thromboplastin. Various dilutions of thromboplastin were added to plasma samples containing 3H-labeled factor X, and the time course of factor X activation was determined. At a 1/250 dilution of rabbit brain thromboplastin the rate of factor X activation in factor VIII or factor IX deficient plasma was only 10% of the activation rate seen for normal or factor XI deficient plasma. Reconstitution of the deficient plasmas with factors VIII or IX, respectively, restored normal factor X activation. Similar results were obtained when various dilutions of human thromboplastin replaced the rabbit thromboplastin. From these experiments, it is inferred that normal activation of factor X in plasma due to dilute thromboplastin requires factors VII, IX and VIII. An alternative extrinsic pathway that involves factors VII, IX, and VIII may be a major physiologic extrinsic pathway, and this pathway may help to explain the clinical observations of bleeding diatheses in patients deficient in factors IX or VIII. 相似文献
50.