全文获取类型
收费全文 | 1149篇 |
免费 | 71篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 44篇 |
妇产科学 | 38篇 |
基础医学 | 125篇 |
口腔科学 | 11篇 |
临床医学 | 140篇 |
内科学 | 306篇 |
皮肤病学 | 21篇 |
神经病学 | 89篇 |
特种医学 | 149篇 |
外科学 | 62篇 |
综合类 | 38篇 |
预防医学 | 73篇 |
眼科学 | 11篇 |
药学 | 98篇 |
中国医学 | 5篇 |
肿瘤学 | 53篇 |
出版年
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 27篇 |
2014年 | 25篇 |
2013年 | 45篇 |
2012年 | 20篇 |
2011年 | 33篇 |
2010年 | 36篇 |
2009年 | 41篇 |
2008年 | 39篇 |
2007年 | 80篇 |
2006年 | 42篇 |
2005年 | 32篇 |
2004年 | 32篇 |
2003年 | 28篇 |
2002年 | 37篇 |
2001年 | 41篇 |
2000年 | 27篇 |
1999年 | 25篇 |
1998年 | 56篇 |
1997年 | 60篇 |
1996年 | 65篇 |
1995年 | 39篇 |
1994年 | 36篇 |
1993年 | 24篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 39篇 |
1988年 | 40篇 |
1987年 | 29篇 |
1986年 | 30篇 |
1985年 | 17篇 |
1984年 | 16篇 |
1983年 | 6篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1972年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有1268条查询结果,搜索用时 15 毫秒
101.
Primary care in the UK has been the subject of numerous changes and reorganizations since 1990. Each innovation in organization, with the exception of fundholding, has been the subject of evaluation. However, the complexities of some innovations make the evaluation process problematic and this is further complicated by the trend towards central policy decision making being subject to local interpretation and implementation, by means of simultaneous devolution and centralization. This paper discusses the challenges and problems posed by attempting to evaluate these new organizations, particularly with regard to whether or not they can be considered to be "successful". It draws specifically on the national evaluation of the total purchasing pilots and indicates how the findings can be applied to primary care groups. 相似文献
102.
肾康片质量标准的研究 总被引:4,自引:0,他引:4
目的:研究肾康片的质量标准并控制该制剂的质量。方法:用薄层色谱法鉴别了肾康片中的黄芪,山茱萸,桑寄生及丹参,用薄层色谱法限量检查屯该制剂中的乌头碱,用双波长薄层扫描法测定了该制剂中黄芪甲苷的含量。结果:乌头碱限量符合中国药典测定,黄芪甲苷的平均回收率为97.5%,其RSD为1.43%。结论:本文的结果显示出这些方法可用于控制该制剂的质量,方法灵敏,简便,专属,准确。 相似文献
103.
A total of 68 major complications of cervical myelography were reported by 220 neuroradiologists in a mail survey. Two-thirds of the complications were attributed to cervical spine hyperextension and one-third to lateral C1-2 puncture. Narrow sagittal diameter of the spinal canal and severe cervical spondylosis were frequent contributing factors to hyperextension injury of the cervical spinal cord. Clinical and radiographic premyelography screening is suggested, with magnetic resonance imaging performed first in patients with spinal canal stenosis, severe spondylosis, and/or myelopathy of any cause. Neck extension should be minimal during myelography. All C1-2 punctures should be monitored with lateral fluoroscopy for accurate needle positioning and prevention of contrast medium injection into the spinal cord. 相似文献
104.
105.
Claire Storey Francine Cheater Jackie Ford & Brenda Leese 《Journal of advanced nursing》2009,65(7):1400-1411
Title. Retaining older nurses in primary care and the community.
Aim. This paper is a report of a study conducted to examine issues associated with the impact of age on the retention of female primary and community care nurses in the National Health Service in England.
Background. Little is known about why older nurses in the primary and community care workforce leave and what might encourage them to stay.
Methods. A cross-sectional survey using a semi-structured postal questionnaire was carried out during 2005. Responses were received from 485 (61%) district nurses, health visitors, school nurses and practice nurses in five primary care trusts in England. Data were analysed to test for associations.
Results. Older nurses were more likely than younger ones to report that their role had lived up to expectations ( P = 0·001). Issues important for older nurses were feeling valued and being consulted when change was implemented. Important factors encouraging nurses to stay were pension considerations, reduced working hours near retirement, and reduced workload. For those with degree-level qualifications, enhanced pay was a factor encouraging retention ( P = 0·044). Nurses might leave in response to high administrative workloads, problems in combining work and family commitments ( P ≤ 0·001), and lack of workplace support ( P = 0·029). Retirement and pensions advice was not widely available.
Conclusion. Since two-thirds of nurses were generally happy in their role, it is important that the conditions necessary to maintain this level of satisfaction are continued throughout a nurse's working life. Nurses may all too easily consider leaving prematurely unless policy makers and managers ensure that their working environment reflects the issues nurses consider to be conducive to retention. 相似文献
Aim. This paper is a report of a study conducted to examine issues associated with the impact of age on the retention of female primary and community care nurses in the National Health Service in England.
Background. Little is known about why older nurses in the primary and community care workforce leave and what might encourage them to stay.
Methods. A cross-sectional survey using a semi-structured postal questionnaire was carried out during 2005. Responses were received from 485 (61%) district nurses, health visitors, school nurses and practice nurses in five primary care trusts in England. Data were analysed to test for associations.
Results. Older nurses were more likely than younger ones to report that their role had lived up to expectations ( P = 0·001). Issues important for older nurses were feeling valued and being consulted when change was implemented. Important factors encouraging nurses to stay were pension considerations, reduced working hours near retirement, and reduced workload. For those with degree-level qualifications, enhanced pay was a factor encouraging retention ( P = 0·044). Nurses might leave in response to high administrative workloads, problems in combining work and family commitments ( P ≤ 0·001), and lack of workplace support ( P = 0·029). Retirement and pensions advice was not widely available.
Conclusion. Since two-thirds of nurses were generally happy in their role, it is important that the conditions necessary to maintain this level of satisfaction are continued throughout a nurse's working life. Nurses may all too easily consider leaving prematurely unless policy makers and managers ensure that their working environment reflects the issues nurses consider to be conducive to retention. 相似文献
106.
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
107.
108.
109.
目的:探讨谷氨酸对脑组织即早基因表达的影响以及醋酸锌对谷氨酸诱导c-fos和c-jun过度表达的拮抗作用。方法:体外小鼠海马脑片培养;在培养基中加入200μmol/L的谷氨酸(或同时加入谷氨酸和醋酸锌),作用0.5,1,2,3h,然后进行RT-PCR实验,检测c-fos和c-jun的表达变化。结果:200μmol/L谷氨酸处理的脑片中,1-2h期间c-fos的表达升高,当谷氨酸与100μmol/L醋酸锌共同处理脑片时,1-3h期间c-fos表达基本恢复正常;200μmol/L谷氨酸作用下,脑片c-jun表达水平从0.5h起即明显升高,谷氨酸与醋酸锌共同作用时,可见c-jun基因在各检测时段表达基本接近正常。结论:谷氨酸可引起c-fos及c-jun的过度表达,锌离子可拮抗谷氨酸诱导的c-fos和c-jun过度表达作用,使二基因表达恢复正常。 相似文献
110.
Ultraviolet irradiation of blood prevents transfusion-induced sensitization and marrow graft rejection in dogs 总被引:1,自引:1,他引:0
In a canine model using DLA-identical littermate pairs, we have shown that a regimen of three transfusions of donor blood given 24, 17, and 10 days before transplant uniformly leads to marrow graft rejection, presumably due to sensitization to minor (non-DLA) histocompatibility antigens. Untransfused dogs uniformly achieve sustained engraftment. In the present study, we investigated whether the exposure of blood to ultraviolet (UV) light (220-300 nm) prior to transfusion prevented sensitization of the recipient and allowed for successful marrow engraftment. Ten dogs were each given three pretransplant transfusions from the marrow donor. Each transfusion consisted of 50 mL of whole blood exposed in vitro to UV light for a total of 1.35 J/cm2. All ten dogs achieved engraftment. In contrast, all four dogs that had received sham-exposed transfusions rejected their grafts. In vitro studies revealed that although cell viability was not affected, leukocytes contained in UV-exposed blood were unable to function as stimulator cells in mixed leukocyte cultures or as accessory cells in mitogen- stimulated cultures. These data are consistent with the hypothesis that accessory cells are involved in transfusion-induced sensitization. We conclude that in vitro exposure of blood to UV light before transfusion prevents sensitization and allows for subsequent marrow engraftment. 相似文献