全文获取类型
收费全文 | 1184篇 |
免费 | 74篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 118篇 |
妇产科学 | 11篇 |
基础医学 | 92篇 |
口腔科学 | 36篇 |
临床医学 | 172篇 |
内科学 | 273篇 |
皮肤病学 | 15篇 |
神经病学 | 24篇 |
特种医学 | 214篇 |
外科学 | 71篇 |
综合类 | 35篇 |
预防医学 | 130篇 |
眼科学 | 7篇 |
药学 | 38篇 |
1篇 | |
肿瘤学 | 30篇 |
出版年
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 29篇 |
2012年 | 24篇 |
2011年 | 31篇 |
2010年 | 44篇 |
2009年 | 51篇 |
2008年 | 31篇 |
2007年 | 12篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 20篇 |
2003年 | 17篇 |
2002年 | 25篇 |
2001年 | 19篇 |
2000年 | 16篇 |
1999年 | 29篇 |
1998年 | 85篇 |
1997年 | 84篇 |
1996年 | 89篇 |
1995年 | 59篇 |
1994年 | 54篇 |
1993年 | 46篇 |
1992年 | 28篇 |
1991年 | 28篇 |
1990年 | 13篇 |
1989年 | 37篇 |
1988年 | 33篇 |
1987年 | 37篇 |
1986年 | 19篇 |
1985年 | 31篇 |
1984年 | 22篇 |
1983年 | 19篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1973年 | 3篇 |
1971年 | 4篇 |
1966年 | 2篇 |
排序方式: 共有1269条查询结果,搜索用时 15 毫秒
161.
Interleukin 1 induces human marrow stromal cells in long-term culture to produce granulocyte colony-stimulating factor and macrophage colony- stimulating factor 总被引:11,自引:0,他引:11
Fibbe WE; van Damme J; Billiau A; Goselink HM; Voogt PJ; van Eeden G; Ralph P; Altrock BW; Falkenburg JH 《Blood》1988,71(2):430-435
Pure interleukin 1 (IL 1) was found to stimulate established human bone marrow stromal layers in long-term culture to produce colony- stimulating activity (CSA). Maximal concentrations in the culture medium were reached 24 hours after a single IL 1 pulse. The effect could be neutralized by a specific rabbit anti-IL 1 antiserum. Stromal layers, once stimulated by IL 1, continued to release CSA into the culture medium in the absence of exogenous IL 1. A second IL 1 pulse induced CSA release in an identical manner, as did the primary stimulation, indicating that the CSA released was actively produced. Using specific immunologic assays, both granulocyte colony-stimulating factor (G-CSF) and macrophage CSF (M-CSF) could be identified in the culture supernatants, and production of both factors was inducible by IL 1. Shortly after initiation of the long-term marrow cultures "spontaneous" G-CSF and M-CSF release occurred. The release of G-CSF diminished following addition of the anti-IL 1 antiserum, indicating that endogenous production of IL 1 by stromal cells had contributed to this effect. These results further support the role of IL 1 as an important modulator of CSF production by cells of the hematopoietic microenvironment. 相似文献
162.
Conditions were developed in which 80% to 90% of platelet fibrinogen could be routinely purified in nondegraded form from the fluid phase of platelet suspensions stimulated with the calcium ionophore, A23187, in the presence of calcium, leupeptin, and prostaglandin E1. Fibrinogen was separated from other released proteins by chromatography on diethylaminoethanol (DEAE)-cellulose using a continuous pH and ionic strength gradient. Purified platelet fibrinogen, greater than 98% homogeneous by immunoelectrophoresis and sodium-dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE), consisted of intact A alpha, B beta and gamma A chains, but not gamma' chains, and was 95% to 96% clottable. Platelet fibrinogen was shown to compete for the binding of radiolabeled plasma fibrinogen to ADP-activated platelets in a manner identical to that of unlabeled plasma fibrinogen itself. Also, at equivalent protein concentrations, platelet and plasma fibrinogens supported platelet aggregation to an equivalent extent. Based upon these results, we conclude that there is no significant difference between platelet and plasma fibrinogen with respect to their size, their clottability, their affinity for the activated platelet fibrinogen receptor, or their capacity to support subsequent platelet aggregation. 相似文献
163.
Effects of ambient ozone on respiratory function in healthy adults exercising outdoors 总被引:3,自引:0,他引:3
D M Spektor M Lippmann G D Thurston P J Lioy J Stecko G O'Connor E Garshick F E Speizer C Hayes 《The American review of respiratory disease》1988,138(4):821-828
The effect of exposure to ozone (O3) in ambient air on respiratory function was studied in 30 healthy adult nonsmokers engaged in a regular daily program of outdoor exercise in Tuxedo, NY during the summer of 1985. Each subject did the same exercise each day, but exercise intensity and duration varied widely between subjects, with minute ventilation ranging from 20 to 153 L and duration ranging from 15 to 55 min. Spirometry was performed immediately before and after each exercise period. O3 concentrations during exercise ranged from 21 to 124 parts per billion (ppb). All measured functional indexes showed significant (p less than 0.01) O3-associated mean decrements with FVC at -2.1 ml/ppb, FEV1 at -1.4 ml/ppb, PEFR at -9.2 ml/s/ppb, FEF25-75 at -6.0 ml/s/ppb, and FEV1/FVC at -0.038%/ppb. Mean decrements were smaller for 10 subjects with minute ventilations greater than 100 L than for 10 other subjects with minute ventilations between 60 and 100 L or for the 10 subjects with minute ventilations below 60 L. Overall, the functional decrements were similar in magnitude to those we have seen in children engaged in supervised recreational programs in summer camps. For 10 subjects with minute ventilations comparable to those used in controlled 1- and 2-h exposures to O3 in purified air in chambers (50 to 80 L), the effects were about twice as large as those reported for the chamber studies.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
164.
Allogeneic marrow transplantation for refractory anemia: a comparison of two preparative regimens and analysis of prognostic factors 总被引:3,自引:3,他引:3
Anderson JE; Appelbaum FR; Schoch G; Gooley T; Anasetti C; Bensinger WI; Bryant E; Buckner CD; Chauncey TR; Clift RA; Doney K; Flowers M; Hansen JA; Martin PJ; Matthews DC; Sanders JE; Shulman H; Sullivan KM; Witherspoon RP; Storb R 《Blood》1996,87(1):51-58
From 1990 to 1993 we performed a prospective study of busulfan (16 mg/kg) and cyclophosphamide (120 mg/kg) in 30 patients with refractory anemia (RA) undergoing related (n = 17) or unrelated (n = 13) donor marrow transplantation. Nineteen patients survive disease free (63% 3- year actuarial disease-free survival [DFS]) and no patient relapsed. These results were compared to those of 38 historical controls with RA treated with cyclophosphamide and total body irradiation, of whom 22 are disease-free survivors and 1 relapsed. After correcting for significant variables between the two treatment groups, we found no statistically significant difference in outcome based on preparative regimen. Combining data from these 68 patients plus 2 additional patients with RA treated before 1993 with busulfan and cyclophosphamide, we identified four variables independently associated with improved survival: younger age, shorter disease duration, lower neutrophil count pretransplant, and lower hematocrit pretransplant. We also found that 15 patients 40 to 55 years of age had a 46% 3-year actuarial DFS and 26 patients receiving unrelated or mismatched related donor marrow had a 50% 3-year actuarial DFS. We conclude that there does not appear to be any significant difference in outcome based on preparative regimen in this patient population. In addition, allogeneic bone marrow transplantation may be a reasonable approach to therapy of RA early after diagnosis. However, whether early intervention with transplantation prolongs survival over that expected without transplantation cannot be ascertained with certainty from available data. 相似文献
165.
Bone marrow transplantation for patients with Philadelphia chromosome- positive acute lymphoblastic leukemia 总被引:1,自引:2,他引:1
Forman SJ; O'Donnell MR; Nademanee AP; Snyder DS; Bierman PJ; Schmidt GM; Fahey JL; Stein AS; Parker PM; Blume KG 《Blood》1987,70(2):587-588
We report the treatment outcome of allogeneic bone marrow transplantation in ten patients with Philadelphia chromosome-positive acute lymphoblastic leukemia. Six patients are alive and well for 6 to 30 months (median 19 months) after transplantation. Four patients died with transplant related complications. In view of the poor prognosis associated with this disease, marrow ablation followed by allogeneic or syngeneic marrow grafting may be the preferred treatment modality if a suitable marrow donor is available. 相似文献
166.
Matthews DC; Appelbaum FR; Eary JF; Fisher DR; Durack LD; Bush SA; Hui TE; Martin PJ; Mitchell D; Press OW 《Blood》1995,85(4):1122-1131
In an attempt to decrease the relapse rate after bone marrow transplantation (BMT) for advanced acute leukemia, we initiated studies using 131I-labeled anti-CD45 antibody (BC8) to deliver radiation specifically to hematopoietic tissues, followed by a standard transplant preparative regimen. Biodistribution studies were performed in 23 patients using 0.5 mg/kg trace 131I-labeled BC8 antibody. The BC8 antibody was cleared rapidly from plasma with an initial disappearance half-time of 1.5 +/- 0.2 hours, presumably reflecting rapid antigen- specific binding. The mean radiation absorbed doses (cGy/mCi131I administered) were as follows: marrow, 7.1 +/- 0.8; spleen, 10.8 +/- 1.4; liver, 2.7 +/- 0.2; lungs, 2.1 +/- 0.1; kidneys, 0.7 +/- 0.1; and total body, 0.4 +/- 0.03. Patients with acute myelogenous leukemia (AML) in relapse had a higher marrow dose (11.4 cGy/mCi) than those in remission (5.2 cGy/mCi; P = .001) because of higher uptake and longer retention of radionuclide in marrow. Twenty patients were treated with a dose of 131I estimated to deliver 3.5 Gy (level 1) to 7 Gy (level 3) to liver, with marrow doses of 4 to 30 Gy and spleen doses of 7 to 60 Gy, followed by 120 mg/kg cyclophosphamide (CY) and 12 Gy total body irradiation (TBI). Nine of 13 patients with AML or refractory anemia with excess blasts (RAEB) and two of seven with acute lymphocytic leukemia (ALL) are alive disease-free at 8 to 41 months (median, 17 months) after BMT. Toxicity has not been measurably greater than that of CY/TBI alone, and the maximum tolerated dose has not been reached. This study demonstrates that with the use of 131I-BC8 substantially greater doses of radiation can be delivered to hematopoietic tissues as compared with liver, lung, or kidney, which may improve the efficacy of marrow transplantation. 相似文献
167.
168.
Lymphadenopathy-associated virus antibodies and T cells in hemophiliacs treated with cryoprecipitate or concentrate 总被引:1,自引:0,他引:1
Gjerset GF; McGrady G; Counts RB; Martin PJ; Jason J; Kennedy S; Evatt B; Hansen JA 《Blood》1985,66(3):718-720
Evidence for exposure to lymphadenopathy-associated virus (LAV) was investigated in 48 patients with hemophilia, 15 of whom had been treated exclusively with single-donor cryoprecipitate. The prevalence of antibodies to LAV in all patients was 53% in 1983 and 63% in 1984, while in patients treated only with cryoprecipitate, the prevalence was 31% in 1983 and 40% in 1984. Patients treated with any concentrate had a seroprevalence of 65% in 1983 and 77% in 1984. Seropositive patients were more likely to have a significant reduction in the ratio of helper to suppressor T cells, absolute numbers of helper T cells, and T cell function in vitro. Seven of 18 patients who were seronegative in 1983 had seroconverted by 1984. The relative risk of seroconversion for patients using any concentrate since 1981 compared with those using cryoprecipitate only was 3.9 (P = .04). Nevertheless, the rate of conversion in the latter group was 18% per year. 相似文献
169.
Biliary stricture dilatation: multicenter review of clinical management in 73 patients 总被引:7,自引:0,他引:7
Mueller PR; vanSonnenberg E; Ferrucci JT Jr; Weyman PJ; Butch RJ; Malt RA; Burhenne HJ 《Radiology》1986,160(1):17-22
Eighty-nine biliary strictures in 73 patients who had undergone percutaneous balloon dilatation were reviewed to determine long-term patency rates and clinical management problems. The majority of dilatations were performed in patients with anastomotic strictures (n = 44), iatrogenic strictures (n = 28), and strictures associated with sclerosing cholangitis (n = 17). Patency rates after 36 months or more were 67%, 76%, and 42%, respectively. Complications, mostly minor, occurred in less than 7% of patients. Of patients with significant biliary obstruction, 15% had little or no intrahepatic biliary duct dilatation demonstrated by cross-sectional imaging and/or direct cholangiography. No definite conclusions could be drawn about the utility of long-term internal/external stenting. 相似文献
170.
Cerebral blood flow relationships associated with a difficult tone recognition task in trained normal volunteers 总被引:2,自引:2,他引:0
Holcomb HH; Medoff DR; Caudill PJ; Zhao Z; Lahti AC; Dannals RF; Tamminga CA 《Cerebral cortex (New York, N.Y. : 1991)》1998,8(6):534-542
Tone recognition is partially subserved by neural activity in the right
frontal and primary auditory cortices. First we determined the brain areas
associated with tone perception and recognition. This study then examined
how regional cerebral blood flow (rCBF) in these and other brain regions
correlates with the behavioral characteristics of a difficult tone
recognition task. rCBF changes were assessed using H2(15)O positron
emission tomography. Subtraction procedures were used to localize
significant change regions and correlational analyses were applied to
determine how response times (RT) predicted rCBF patterns. Twelve trained
normal volunteers were studied in three conditions: REST, sensory motor
control (SMC) and decision (DEC). The SMC-REST contrast revealed bilateral
activation of primary auditory cortices, cerebellum and bilateral inferior
frontal gyri. DEC-SMC produced significant clusters in the right middle and
inferior frontal gyri, insula and claustrum; the anterior cingulate gyrus
and supplementary motor area; the left insula/claustrum; and the left
cerebellum. Correlational analyses, RT versus rCBF from DEC scans, showed a
positive correlation in right inferior and middle frontal cortex; rCBF in
bilateral auditory cortices and cerebellum exhibited significant negative
correlations with RT These changes suggest that neural activity in the
right frontal, superior temporal and cerebellar regions shifts back and
forth in magnitude depending on whether tone recognition RT is relatively
fast or slow, during a difficult, accurate assessment.
相似文献