全文获取类型
收费全文 | 1220篇 |
免费 | 69篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 47篇 |
妇产科学 | 13篇 |
基础医学 | 169篇 |
口腔科学 | 39篇 |
临床医学 | 145篇 |
内科学 | 226篇 |
皮肤病学 | 35篇 |
神经病学 | 28篇 |
特种医学 | 242篇 |
外科学 | 92篇 |
综合类 | 24篇 |
预防医学 | 75篇 |
眼科学 | 30篇 |
药学 | 45篇 |
肿瘤学 | 78篇 |
出版年
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 11篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 40篇 |
2012年 | 43篇 |
2011年 | 33篇 |
2010年 | 56篇 |
2009年 | 37篇 |
2008年 | 39篇 |
2007年 | 36篇 |
2006年 | 28篇 |
2005年 | 32篇 |
2004年 | 31篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 14篇 |
1998年 | 48篇 |
1997年 | 61篇 |
1996年 | 56篇 |
1995年 | 53篇 |
1994年 | 48篇 |
1993年 | 32篇 |
1992年 | 23篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 26篇 |
1988年 | 40篇 |
1987年 | 22篇 |
1986年 | 39篇 |
1985年 | 32篇 |
1984年 | 20篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1978年 | 9篇 |
1977年 | 17篇 |
1976年 | 17篇 |
1975年 | 8篇 |
1969年 | 6篇 |
1966年 | 5篇 |
1929年 | 5篇 |
排序方式: 共有1295条查询结果,搜索用时 15 毫秒
91.
Ocular MR imaging and spectroscopy: an ex vivo study 总被引:2,自引:0,他引:2
Gomori JM; Grossman RI; Shields JA; Augsburger JJ; Joseph PM; DeSimeone D 《Radiology》1986,160(1):201-205
Six eyes, freshly enucleated because of choroidal melanoma, were imaged on a 1.4-T superconducting magnetic resonance (MR) imaging system, and relaxation times were calculated for various parts of the eye. Unfixed fresh tissue samples were obtained for nuclear magnetic resonance spectroscopy (NMRS) on a variable-field (0.19-1.4 T) resistive unit. Detailed ocular anatomy was demonstrated. The NMRS relaxation times correlated with the MR imaging intensity patterns. The sensitivity of MR imaging to states of hydration provides an excellent window for appreciation of ocular anatomy. 相似文献
92.
RS de Vreeze D de Jong IH Tielen HJ Ruijter PM Nederlof RL Haas F van Coevorden 《Modern pathology》2009,22(2):223-231
Almost all primary retroperitoneal liposarcomas can be classified as well-/dedifferentiated liposarcoma. Rarely, however, primary retroperitoneal liposarcoma is classified as myxoid/round cell liposarcoma, based on the presence of myxoid areas and vascular crow's feet pattern, which has resulted in a debate on the classification of liposarcoma in the retroperitoneum. Genetically, myxoid/round cell liposarcoma and well-/dedifferentiated liposarcoma are different diseases. Myxoid/round cell liposarcoma is characterized by a translocation causing FUS-CHOP or EWSR1-CHOP fusion, whereas well-/dedifferentiated liposarcoma is characterized by an amplification of the 12q13-15 region, including MDM2 and CDK4 genes. As myxoid/round cell liposarcoma is highly radio- and chemosensitive, differentiation between subtypes is important to optimize treatment. We studied whether primary retroperitoneal liposarcomas diagnosed as myxoid/round cell liposarcoma represent molecularly true myxoid/round cell liposarcoma or are histopathological mimics and represent well-/dedifferentiated liposarcoma. Primary retroperitoneal myxoid/round cell liposarcoma (n=16) were compared to primary extremity myxoid/round cell liposarcoma (n=20). Histopathological and immunohistochemical features were studied. Amplification status of the 12q13-15 region was studied using a multiplex ligation-dependent probe amplification analysis, and FUS-CHOP or EWS-CHOP translocations were studied using RT-PCR. In primary retroperitoneal myxoid/round cell liposarcoma, MDM2 and CDK4 staining was both positive in 12 of 15 cases. In primary extremity myxoid/round cell liposarcoma, MDM2 was negative in 18/20 and CDK4 was negative in all cases. Multiplex ligation-dependent probe amplification showed the amplification of 12q13-15 region in 16/16 primary retroperitoneal myxoid/round cell liposarcomas and in 1/20 primary extremity myxoid/round cell liposarcomas. Translocation was present in all (18/18) primary extremity myxoid/round cell liposarcomas, but absent in all primary retroperitoneal myxoid/round cell liposarcomas. On the basis of immunohistochemical and molecular characteristics, apparent primary retroperitoneal myxoid/round cell liposarcoma can be recognized as well-/dedifferentiated liposarcoma with morphological features mimicking myxoid/round cell liposarcoma. In these cases, treatment should probably be specifically designed as for well-/dedifferentiated liposarcoma. Moreover, finding of myxoid/round cell liposarcoma translocations in a retroperitoneal localization is highly suggestive of metastasis and should prompt search for a primary localization outside the retroperitoneum. 相似文献
93.
The resident as teacher during work rounds 总被引:2,自引:0,他引:2
The resident is a central figure in the education of medical students and other residents. In order to examine the ways in which residents fulfill their teaching responsibilities, the authors observed 14 first- and second-year internal medicine residents as they reviewed a total of 158 cases during work rounds. Inpatient work rounds were selected for study because in this setting an attending faculty member is not present and the resident bears total responsibility for initiating any teaching that occurs. The results of the study indicated that the most frequently observed teaching behaviors were associated with patient care at the bedside: providing a model of appropriate interaction with patients and verifying clinical findings. Away from the bedside, the residents frequently used brief lectures to teach. The least frequently observed teaching behaviors involved referring to the literature, giving feedback, demonstrating techniques and procedures, and asking questions. Following these observations, the authors initiated a course on clinical teaching for residents. 相似文献
94.
95.
Femoral capital osteonecrosis: MR finding of diffuse marrow abnormalities without focal lesions 总被引:13,自引:0,他引:13
Six painful hips in five patients were examined with magnetic resonance (MR) imaging and were found to have diffuse signal abnormalities in the marrow of the femoral head and neck, which extended into the intertrochanteric area in five cases. The abnormal regions were low in signal intensity on images obtained with a short repetition time (TR) and a short echo time (TE) and were isointense or hyperintense on long TR/TE images--findings that have been attributed by others to bone marrow edema. Edema was also seen in marrow just above the acetabulum in two cases. No focal abnormalities characteristic of osteonecrosis were seen. Osteonecrosis was subsequently shown to be present in all six femoral heads at core biopsy (three cases) or by subsequent development of focal MR abnormalities reported to be highly specific for osteonecrosis (three cases). The affected hips had been radiographically normal or subtly osteopenic and had shown intense radionuclide uptake in the femoral head at scintigraphy, with lesser abnormality in the neck and intertrochanteric region. Follow-up MR examinations of five of the six femoral heads showed the diffuse abnormalities to have been transient. Although diffuse MR abnormalities in the proximal femur are not specific, they may indicate the presence of osteonecrosis of the femoral head. 相似文献
96.
Segal I; Sharer NM; Kay PM; Gutteridge JM; Braganza JM 《QJM : monthly journal of the Association of Physicians》1996,89(1):45-53
Vitamin C can be used to overcome oxidative stress and ease pain in chronic
pancreatitis. But its use is deprecated in conditions of tissue iron
overload, because its bioactive form, ascorbate, can accelerate
free-radical reactions that are driven by transition metals. We measured
iron, ascorbate and copper in Sowetan Blacks (RSA) with chronic
pancreatitis, obtaining serum/plasma from 14 consecutive patients and 15
controls. Compared with data from corresponding groups in Manchester,
African samples had less ascorbate (p < 0.0001), but more caeruloplasmin
(p < 0.0001). African and British controls had comparable iron and
iron-binding capacity. Plasma from African patients had less ascorbate than
that from African controls (p < 0.005) and in six samples, ferritin
exceeded 300 micrograms/l (677 pmol/l). Low- molecular-mass iron or copper,
capable of participating in free radical reactions, was not detected.
British patients, had similar caeruloplasmin levels to African patients but
higher ascorbate levels. There is no evidence of iron overload in our
African samples. Outwardly healthy controls from Soweto have elevated
levels of caeruloplasmin, possibly to compensate for dietary deficiency of
ascorbate. Persistent oxidative stress is a unifying feature of chronic
pancreatitis, but its degree is higher in African than British patients.
Supplements of vitamin C should be safe in Blacks of southern Africa.
相似文献
97.
Mary Beth Flanders Stepans RNC MS Norma Wilkerson RN PhD 《Journal of the American Academy of Nurse Practitioners》1993,5(3):105-113
Women who smoke and breast-feed pose an unknown threat to their infants' health. In this pilot study, relationships between ingestion of nicotine in breast milk and physiologic effects in the infant were investigated. Infant physiologic effects measured were temperature, pulse, respiration, systolic blood pressure, and oxygen saturation. Five smoking and five nonsmoking mother-infant pairs were studied. Breast milk was analyzed for nicotine using gas chromatography. Breast milk from smoking mothers contained a mean of 33.1 ng/mL of nicotine while the breast milk from nonsmoking mothers contained a mean of less than 6.45 ng/mL of nicotine. Infant physiologic measures were taken before and 20 min after breast-feeding. After breast-feeding, infants of smoking mothers had a significant change in respirations and oxygen saturation while infants of nonsmoking mothers had a significant change in pulse only. Results provide a scientific basis for counseling smoking, breast-feeding mothers. 相似文献
98.
自体造血干细胞的体外净化 总被引:1,自引:0,他引:1
目的:综合分析自体造血干细胞体外净化的方法。资料来源:应用计算机检索Medline 1991-01/2003-12有关自体造血干细胞体外净化方法的文章,检索词“purging,HSCT”,并限定文章语言种类为English。同时计算机检索CNKI数据库1991-01/2003-12有关自体造血干细胞体外净化方法的文章,检索词“体外净化,PUVA”,并限定文章语言种类为中文。资料选择:对相关资料进行整理,选取同一领域、不同方面的文献,以近期发表或权威杂志的文章优先。资料提炼:共检索到42篇有关自体造血干细胞体外净化方法的文献,其中24篇文章符合要求。排除18篇,其中15篇系重复同一研究,3篇为Meta分析。资料综合:自体造血干细胞的体外净化方法很多,如物理方法、生物学方法、药物方法、免疫净化、基因净化等。每种净化方法都有其各自的优势和不足,如淋巴系统疾病可以采用免疫净化;慢性粒细胞白血病患者可考虑反义技术;大多数患者则均可以考虑药物净化的方法。结论:针对不同的疾病,可以选择不同的净化方法,还可以将几种净化方法联合起来,其效果和方法的改进也在不断的研究探索中。 相似文献
99.
Reduction in transmission of hepatitis C after the introduction of a heat-treatment step in the production of C1-inhibitor concentrate 总被引:1,自引:0,他引:1
BACKGROUND: The transmission of viral infections via protein concentrates made from a large pool of plasma depends on the selection of donors, fractionation process, and virucidal methods. To date, no data are available on the infectivity risk of plasma concentrates of the inhibitor of the first component of complement (C1-INH). STUDY DESIGN AND METHODS: The prevalence of blood-borne viral infections and levels of transaminases were evaluated in patients treated with a large- pool plasma concentrate of the inhibitor of C1-INH before and after the introduction of virucidal methods. The study included 85 patients with hereditary angioedema and 4 with acquired angioedema. The patients were divided into three groups: 1) 48 untreated patients; 2) 22 patients treated with non-virus-inactivated C1-INH concentrates; and 3) 19 patients treated with virus-inactivated concentrates. Serum samples obtained at various times after the infusion of concentrate were assayed for alanine amino-transferase and tested for hepatitis B surface antigen and antibodies to hepatitis C virus (anti-HCV) and human immunodeficiency virus (anti-HIV); anti-HCV-negative subjects exposed to the concentrate were also tested for HCV RNA. RESULTS: Prevalences of HCV infection and elevated alanine aminotransferase are significantly lower in patients treated with virus-inactivated concentrates than in those exposed to non-virus-inactivated concentrates. No patients were anti-HIV positive. CONCLUSION: This study suggests that C1-INH concentrates transmitted HCV, but that the virucidal methods adopted are effective in reducing the infectivity. 相似文献
100.
BACKGROUND: Polyethylene glycol (PEG) has been shown to potentiate antigen-antibody reactions. STUDY DESIGN AND METHODS: To investigate the utility of PEG in pretransfusion testing, a blinded comparison study of PEG and a low-ionic-strength additive solution (LISS) was conducted. A total of 500 patient samples were tested in parallel with reagent antibody-detection cells using blind-coded PEG and LISS potentiators. RESULTS: In 34 (34%) of 100 samples with known antibodies in the Rh, Kell, Duffy, Kidd, and MNS systems, PEG antiglobulin reactions were stronger (total score, 382) than LISS antiglobulin reactions (total score, 216), and in 66 cases (66%), they were equal to those of LISS. Of 400 samples without detectable antibodies, 384 were negative with PEG and LISS, and 16 were positive in PEG tests and negative in LISS. Seven of the 16 were clinically important antibodies (D, 1; E, 3; Fya, 1; Jka; 1; Jkb, 1), and four were clinically benign antibodies (Le(a), 2; McCc, 1; Sda, 1). Five of the 16 demonstrated inconclusive PEG reactions, for a false-positive rate of 5 in 400 (1.3%). Of the 500 samples, none was negative in PEG tests and positive in LISS (0% false-negative rate). CONCLUSION: Although PEG demonstrates a relatively high false-positive rate, PEG is more sensitive than LISS in detecting clinically significant antibodies. 相似文献