全文获取类型
收费全文 | 23995篇 |
免费 | 2467篇 |
国内免费 | 105篇 |
专业分类
耳鼻咽喉 | 196篇 |
儿科学 | 909篇 |
妇产科学 | 651篇 |
基础医学 | 3413篇 |
口腔科学 | 371篇 |
临床医学 | 3466篇 |
内科学 | 5180篇 |
皮肤病学 | 575篇 |
神经病学 | 2498篇 |
特种医学 | 556篇 |
外国民族医学 | 4篇 |
外科学 | 2342篇 |
综合类 | 206篇 |
一般理论 | 5篇 |
预防医学 | 2411篇 |
眼科学 | 296篇 |
药学 | 1568篇 |
中国医学 | 19篇 |
肿瘤学 | 1901篇 |
出版年
2023年 | 244篇 |
2022年 | 377篇 |
2021年 | 762篇 |
2020年 | 607篇 |
2019年 | 917篇 |
2018年 | 1008篇 |
2017年 | 787篇 |
2016年 | 836篇 |
2015年 | 884篇 |
2014年 | 1068篇 |
2013年 | 1452篇 |
2012年 | 1847篇 |
2011年 | 1754篇 |
2010年 | 1123篇 |
2009年 | 1001篇 |
2008年 | 1501篇 |
2007年 | 1485篇 |
2006年 | 1374篇 |
2005年 | 1288篇 |
2004年 | 1213篇 |
2003年 | 1081篇 |
2002年 | 1002篇 |
2001年 | 216篇 |
2000年 | 196篇 |
1999年 | 215篇 |
1998年 | 240篇 |
1997年 | 189篇 |
1996年 | 148篇 |
1995年 | 148篇 |
1994年 | 128篇 |
1993年 | 108篇 |
1992年 | 83篇 |
1991年 | 90篇 |
1990年 | 87篇 |
1989年 | 75篇 |
1988年 | 66篇 |
1987年 | 48篇 |
1986年 | 64篇 |
1985年 | 56篇 |
1984年 | 61篇 |
1983年 | 61篇 |
1982年 | 69篇 |
1981年 | 69篇 |
1980年 | 41篇 |
1979年 | 28篇 |
1978年 | 35篇 |
1977年 | 42篇 |
1976年 | 50篇 |
1975年 | 38篇 |
1974年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
Rongbao Zhao Shrikanta Chattopadhyay Marie Hanscom I David Goldman 《Clinical cancer research》2004,10(24):8735-8742
Prior studies from this laboratory documented the prevalence of methotrexate (MTX) transport activity with a low pH optimum in human solid tumor cell lines. In HeLa cells, this low pH activity has high affinity for pemetrexed [PMX (Alimta)] and is reduced folate carrier (RFC)-independent because it is not diminished in a RFC-null subline (R5). R5 cells also have residual transport activity, with high specificity for PMX, at neutral pH. In the current study, a R5 subline, R1, was selected under MTX selective pressure at a modest reduction in pH. There was markedly decreased MTX and PMX transport at both pH 5.5 and pH 7.4. When MTX was removed, there was a slow return of transport activity, and when MTX was added back, there was loss of transport at both pH values within 8 weeks. In R1 cells, there was a marked decrease in accumulation of PMX, MTX, and folic acid along with a decrease in growth inhibition by these and other antifolates that require a facilitative process to gain entry into cells. These data demonstrate that (i) RFC-independent transport in HeLa cells at low and neutral pH contributes to antifolate activity (in particular, to PMX activity) and can be diminished by antifolate selective pressure and (ii) the loss of these activities results in marked resistance to PMX, an agent for which there is little or no loss of activity when transport mediated by RFC is abolished. These observations suggest that transport activity in RFC-null HeLa R5 cells at neutral and low pH may reflect the same carrier-mediated process. 相似文献
143.
D Chaoui O Legrand N Roche M Cornet A Lefebvre R Peffault de Latour L Sanhes G Huchon J-P Marie A Rabbat 《Leukemia》2004,18(4):670-675
Acute respiratory failure and infectious pneumonia are the major causes of death during induction chemotherapy of acute leukemia. However, the causes, incidence and prognostic value of all respiratory events (REs) occurring in this context have never been assessed prospectively. We recruited 65 consecutive patients with newly diagnosed acute leukemia into a 1-year prospective study (December 2000-November 2001) to evaluate the incidence and prognostic value of these events. REs were frequent: 38 were recorded in 30 patients. There was a significant relationship between REs and pre-existing respiratory disease and/or smoking. REs were caused by infection in 34% of cases, by an established cause other than infection in 42% and had an undetermined cause in 24%. Poor early outcome (death within 45 days of starting induction chemotherapy) in patients experiencing an RE was independently associated with a >25/min respiratory rate (P=0.003) and the nonachievement of complete remission (CR) (P<0.0001). Predictors of overall survival in the entire patient population were the absence of CR (P<0.0001), REs (P=0.02) and a > or =2 performance status (P=0.03). In conclusion, REs are frequent during induction chemotherapy of acute leukemia and represent an independent prognostic factor of poor outcome, regardless of their cause. 相似文献
144.
Antineoplastic effects of partially HLA-matched irradiated blood mononuclear cells in patients with renal cell carcinoma. 总被引:11,自引:0,他引:11
Roger K Strair Dale Schaar Daniel Medina Mary B Todd Joseph Aisner Robert S DiPaola Jacqueline Manago Beth Knox Amanda Jenkinson Rachelle Senzon Christina Baker Dudek Liesel Marie Ciardella Mercy Kuriyan Arnold Rubin Edmund C Lattime 《Journal of clinical oncology》2003,21(20):3785-3791
PURPOSE: Vaccines, cytokines, and other biologic-based therapies are being developed as antineoplastic agents. Many of these agents are designed to induce an autologous immune response directed against the malignancy. In contrast, hematopoietic stem-cell transplantation is being developed as a form of allogeneic immunotherapy. This study tests the tolerance and antineoplastic activity of sequential infusions of partially HLA-matched allogeneic blood mononuclear cells (obtained from relatives) when administered outside of the context of a hematopoietic stem-cell transplantation. The cells are irradiated to prevent graft-versus-host disease. PATIENTS AND METHODS: Fifteen patients with relapsed or refractory malignancies for which no standard therapy was available were enrolled onto a clinical trial designed to assess the tolerability and antineoplastic effects of irradiated partially HLA-matched blood mononuclear cells obtained from relatives. RESULTS: There was disease regression in three patients with metastatic renal cell carcinoma during treatment. There was disease progression in six patients with metastatic renal cell carcinoma and two patients with metastatic melanoma during treatment. There was no change in disease state in several other patients. CONCLUSION: Irradiated allogeneic blood mononuclear cells administered outside the context of hematopoietic stem-cell transplantation may induce disease responses in patients with relapsed or refractory malignancies. Transfusion of irradiated allogeneic blood mononuclear cells should be developed further as a novel therapeutic antineoplastic approach. 相似文献
145.
Jean-Pierre Valla Lise Bergeron Michelle Bidaut-Russell Marie St-Georges Nathalie Gaudet 《Journal of child psychology and psychiatry, and allied disciplines》1997,38(6):717-724
Reliability of the Dominic-R, a. questionnaire combining visual and auditory stimuli, was tested in 340 community children aged 6 to 11 years. Test-retest reliability of symptoms of, and of symptom scores of, DSM-III-R disorders including simple phobias, separation anxiety disorder, overanxious disorder, depression/dysthymia, attention deficit/ hyperactivity disorder, oppositional defiant disorder, and conduct disorder was assessed. Most symptoms yielded kappas greater than .40, and ICCs ranged from .74 to .81. In conclusion, reliability of the Dominic-R compares favourably with that of other child assessment questionnaires. 相似文献
146.
Dietary factors and the risk of squamous cell esophageal cancer among black and white men in the United States 总被引:4,自引:0,他引:4
Linda Morris Brown Christine A. Swanson Gloria Gridley G. Marie Swanson Debra T. Silverman Raymond S. Greenberg Richard B. Hayes Janet B. Schoenberg Linda M. Pottern Ann G. Schwartz Jonathan M. Liff Robert Hoover Joseph F. Fraumeni 《Cancer causes & control : CCC》1998,9(5):467-474
Objectives: To investigate dietary factors for squamous cell esophageal cancer and whether these factors may contribute to the five-fold higher incidence of this cancer in the black versus white population of the United States.Methods: Data from a food frequency questionnaire were analyzed for 114 white men and 219 black men with squamous cell esophageal cancer, and 681 white and 557 black male controls from three areas of the United States who participated in a population-based case-control study of esophageal cancer.Results: Protective effects were associated with intake of raw fruits and vegetables (odds ratio for high versus low consumers=0.3 in both white and black men) and use of vitamin supplements (especially vitamin C; odds ratio for high versus low consumers=0.4 in both races), with the frequency of consumption of raw fruits and vegetables and vitamin supplements being greater for white than black controls. In addition, elevated risks were associated with high versus low intake of red meat (OR=2.7 for blacks and 1.5 for whites) and processed meat (OR=1.6 for blacks and 1.7 for whites), with the levels of consumption being greater for black than white controls.Conclusions: In the United States, these dietary factors may contribute in part to the much higher incidence of squamous cell esophageal cancer among black compared to white men. 相似文献
147.
Obstetric outcome in 232 ovum donation pregnancies 总被引:3,自引:0,他引:3
Hossam I. Abdalla Consultant Anne Billett Clinical Research Fellow rew K. S. Kan Clinical Research Fellow Sabah Baig Clinical Research Fellow Marie Wren Infertility Specialist Lena Korea Ovum Donation Co-ordinator John W. W. Studd Consultant 《BJOG : an international journal of obstetrics and gynaecology》1998,105(3):332-337
148.
Marie A McAnuff Wayne W Harding Felix O Omoruyi Helen Jacobs Errol Y Morrison Helen N Asemota 《Food and chemical toxicology》2005,43(11):1667-1672
In this study, three steroidal sapogenins (Delta3 diosgenin, diosgenin, and pennogenin) and the phytosterols, stigmasterol and beta-sitosterol were isolated from Jamaican bitter yam, Dioscorea polygonoides. Their effects on fasting blood glucose and intestinal amylase and ATPases in streptozotocin-induced diabetic rats were studied. The diabetic rats (fed supplemented and unsupplemented diets) lost weight significantly compared to the normal group. There was a significant increase in the activity of alpha-amylase in the proximal region of the small intestinal mucosa of diabetic rats fed sapogenin extract or commercial diosgenin. However, this did not result in increased fasting blood glucose. Instead, supplementation of the diet with bitter yam sapogenin extract significantly decreased fasting blood glucose compared to the diabetic group. Supplementation of the diet with bitter yam sapogenin extract or commercial diosgenin significantly reduced Na+-K+-ATPase activity in all three regions compared to the diabetic control group. Commercial diosgenin supplementation resulted in a significant increase in Ca2+ ATPase activity in proximal region compared to the diabetic control and bitter yam sapogenin extract groups. The effect of bitter yam sapogenin extract or commercial diosgenin on intestinal Na+-K+-ATPase activity could account for their hypoglycemic properties. However, there was adverse effect on the body weight. 相似文献
149.
Barry N Wasserman Norman B Medow Marie Homa-Palladino Mary Ellen Hoehn 《Journal of AAPOS》2004,8(2):175-181
PURPOSE: To report the results of a survey of the members of the American Association of Pediatric Ophthalmology and Strabismus (AAPOS) regarding the treatment of periocular capillary hemangiomas. METHODS: A survey was delivered to the 600 members of AAPOS. Surveys were returned via facsimile. Results were collected in a computerized spreadsheet and then tabulated and analyzed. RESULTS: Of the 600 AAPOS members, 225 responded to the survey. The results showed that intralesional steroid injection is the most commonly used treatment modality for periorbital capillary hemangiomas. Oral steroids and excision were also commonly used in the treatment of these lesions. CONCLUSIONS: Further controlled studies are needed to determine which treatment modality offers the most benefit and least risk. More standardization based on these studies is necessary to improve treatment of periocular capillary hemangiomas. 相似文献
150.
Samuel R. Friedman Barbara Tempalski Hannah Cooper Theresa Perlis Marie Keem Risa Friedman Peter L. Flom 《Journal of urban health》2004,81(3):377-400
This article estimates the population prevalence of current injection drug users (IDUs) in 96 large US metropolitan areas
to facilitate structural analyses of its predictors and sequelae and assesses the extent to which drug abuse treatment and
human immunodeficiency virus (HIV) counseling and testing are made available to drug injectors in each metropolitan area.
We estimated the total number of current IDUs in the United States and then allocated the large metropolitan area total among
large metropolitan areas using four different multiplier methods. Mean values were used as best estimates, and their validity
and limitations were assessed. Prevalence of drug injectors per 10,000 population varied from 19 to 173 (median 60; interquartile
range 42–87). Proportions of drug injectors in treatment varied from 1.0% to 39.3% (median 8.6%); and the ratio of HIV counseling
and testing events to the estimated number of IDUs varied from 0.013 to 0.285 (median 0.082). Despite limitations in the accuracy
of these estimates, they can be used for structural analyses of the correlates and predictors of the population density of
drug injectors in metropolitan areas and for assessing the extent of service delivery to drug injectors. Although service
provision levels varied considerably, few if any metropolitan areas seemed to be providing adequate levels of services. 相似文献