首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17824篇
  免费   2122篇
  国内免费   439篇
耳鼻咽喉   237篇
儿科学   306篇
妇产科学   138篇
基础医学   1680篇
口腔科学   1051篇
临床医学   1244篇
内科学   1512篇
皮肤病学   586篇
神经病学   526篇
特种医学   2478篇
外国民族医学   15篇
外科学   1654篇
综合类   1889篇
现状与发展   1篇
预防医学   1288篇
眼科学   226篇
药学   925篇
  6篇
中国医学   363篇
肿瘤学   4260篇
  2024年   28篇
  2023年   260篇
  2022年   324篇
  2021年   765篇
  2020年   638篇
  2019年   657篇
  2018年   664篇
  2017年   664篇
  2016年   786篇
  2015年   828篇
  2014年   1286篇
  2013年   1612篇
  2012年   1103篇
  2011年   1087篇
  2010年   843篇
  2009年   803篇
  2008年   817篇
  2007年   788篇
  2006年   729篇
  2005年   679篇
  2004年   608篇
  2003年   547篇
  2002年   436篇
  2001年   398篇
  2000年   318篇
  1999年   287篇
  1998年   254篇
  1997年   242篇
  1996年   253篇
  1995年   172篇
  1994年   148篇
  1993年   132篇
  1992年   110篇
  1991年   130篇
  1990年   104篇
  1989年   115篇
  1988年   99篇
  1987年   80篇
  1986年   81篇
  1985年   94篇
  1984年   69篇
  1983年   63篇
  1982年   50篇
  1981年   44篇
  1980年   57篇
  1979年   37篇
  1978年   21篇
  1977年   26篇
  1976年   21篇
  1975年   15篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
探讨在医院信息系统支持下,以信息共享为基础,对放射检查流程进行优化与再造的具体方法。达到减少冗余环节,减少病人等待时间,减轻综合成本的目的。同时提高医务人员工作效率,提升医疗与服务质量。  相似文献   
992.
目的:通过低剂量辐射兴奋效应的动物模型,进一步探讨低剂量X射线全身照射对小鼠松果腺细胞凋亡的影响。方法:采用0.075Gy X射线全身照射后不同时间间隔取松果腺,采用流式细胞术(FCM)检测照射后不同时间松果腺细胞凋亡百分率的时程变化。结果:低剂量电离辐射全身照射12h、24h、48h后松果腺细胞凋亡百分率降低(P〈0.01)。结论:低剂量辐射可抑制松果腺细胞的凋亡。  相似文献   
993.
OBJECTIVES—To evaluate the relation between exposure to ground radon levels and leukaemia among children using existing population and disease registers.
DESIGN—Ecological correlation study.
SETTING—The county of Östergötland in Sweden.
METHODS—Every child born in the county between 1979 and 1992 was mapped to the property centroid coordinates by linking addresses in the population and property registers. Population maps were overlaid with radon maps and exposure at birth and each subsequent year was quantified as high, normal, low or unknown. This was analysed with data from the tumour registry. Standardised mortality ratios (SMRs) were calculated using the age and sex specific rates for Sweden for the year 1995.
RESULTS—90 malignancies occurred among 53 146 children (498 887 person years) who formed the study population. SMRs for acute lymphatic leukaemia (ALL) among children born in high, normal and low risk areas were 1.43, 1.17 and 0.25 respectively. The relative risk for the normal risk group and high risk group as compared with the low risk group was 4.64 (95% CI 1.29, 28.26) and 5.67 (95% CI 1.06, 42.27). The association between ALL and continued residence at normal or high risk areas showed a similar trend. No association between radon risk levels and any other malignancy was seen.
CONCLUSION—Children born in and staying at areas where the risk from ground radon has been classified as low are less likely to develop ALL than those born in areas classified as normal and high risk.


  相似文献   
994.
用60Co-γ射线对家兔进行全身慢性均匀照射(0.05GY/α),当累积剂量分别达到0.05;0.10,0.15,0.20.0.25,0.3OGY时,静脉取血,常规条件下培养,分别在淋巴细胞的C0(培养前)和G2期(培养48h)以1.5GyYχ射线一次照射。培养至52h制备染色体标本,观察家兔接受不同低剂量γ射线(D1)全身照射后,对相继较大剂量χ射线(D2)所诱导的细胞遗传学损伤的抗性,结果表明在G0期和G2期受大剂量γ射线照射后,D1分别在0.15Gy和0.20GY上可诱导出明显的适应性反应(P<0.05),而在0,10或0.15GY以下则不能诱导出适应性反应,从而为能诱导出适应性反应的最低D1剂量提供了参考。  相似文献   
995.
Summary Radiation-induced damage to the central nervous system is believed to be targeted to glial or endothelial cells or both, although the pathophysiology of this process is still poorly understood. A series of experiments were, therefore, conducted, including irradiation to primary rat astrocytes (in vitro) and rat spinal cords (in vivo). The levels of plasminogen activators (uPA and tPA) and their inhibitors (PNI and PAI-1) were determined by fibrin zymography, ELISA, amidolytic activity assay, complex formation, and Western blot analysis. Fibrin zymography revealed the presence of Mr 48,000 (uPA) and Mr 68,000 (tPA) lytic bands that were increased in irradiated samples. Three- to four-fold higher levels of tPA and 8- to 10-fold higher levels of uPA were detected in irradiated samples. Western blot analysis confirmed the presence of a 51-kDa band (PAI-1) in irradiated samples. PAI-1 is undetectable in nonirradiated spinal cord. Serum-free medium and cell and spinal cord extracts of nonirradiated samples showed a 43-kDa band (PNI), the intensity of which is decreased in irradiated samples. Four- to five-fold decreased levels of PNI were detected in irradiated serum-free media and cell extracts, but no levels of PNI were detected in irradiated spinal cord extracts. This study provides additional information regarding the proposed roles of plasminogen activators and their inhibitors in the development of CNS damage after irradiation.  相似文献   
996.
Ductal carcinoma in situ (DCIS) is an early, localized stage of breast carcinoma that has an excellent prognosis when it is properly treated. The significant increase in the frequency of diagnosis of DCIS in recent years is the result of both better recognition of DCIS among pathologists and widespread use of screening mammography. Multicentricity, bilaterality and histologic subtype are important considerations in the management of this disease. The clinical presentation of DCIS is the presence of either a palpable mass or a mammographic abnormality, most frequently in the form of an area of microcalcifications.For several decades, total mastectomy was considered the appropriate treatment for DCIS, and it should still be considered the standard to which more conservative forms of treatment must be compared. Breast conservation surgery has been used with increasing frequency in the treatment of DCIS but the adequacy of this approach remains subject to controversy. Segmental mastectomy alone may be applied with caution in carefully selected patients, while the rest of the patients undergoing breast conservation surgery should be treated with breast irradiation. Axillary node dissection is generally considered unnecessary in the treatment of DCIS. There is no role for adjuvant chemotherapy in the management of this disease. The role of tamoxifen in the treatment of DCIS is not clearly defined and it should be given only to patients enrolled in clinical trials. Ongoing research should clarify the controversies surrounding DCIS and enable us to define the optimal management for this disease.  相似文献   
997.
998.
The outcome of radiotherapy in patients with stage I testicular seminoma was evaluated. During the period 1960–89 (inclusive) 270 patients with stage I seminoma of the testis received radiotherapy to the para-aortic nodes and ipsilateral hemipelvis following radical orchidectomy. Two hundred and fifty seven patients (95.2%) received a minimum tumour dose of 30Gy in 20 daily fractions using 4–6 MV photons. The 5 year overall and recurrence-free survival rates were 97 and 95%, respectively. Only eight of the 270 patients relapsed and three were cured with ‘salvage’therapies. Of the 11 patients who died, four deaths (36%) were the result of uncontrolled testicular cancer, six (55%) intercurrent illness and one (9%) the result of attempted salvage. Patients staged and treated prior to 1979 had a significantly worse disease-free survival compared to patients treated during and after 1979. As side effects were negligible, it was concluded that radiotherapy for stage I seminoma provides excellent cure rates. The difficulties arranging a ‘surveillance’programme in so large a State as Queensland are discussed.  相似文献   
999.
We reviewed the courses of patients treated during childhood or adolescence for thyroid cancer to estimate the frequency of, and to identify possible risk factors for, the occurrence of second malignant tumors in this population. We identified all patients treated for thyroid cancer in a cohort of 1,406 pediatric cancer patients who were diagnosed prior to 20 years of age during the period January 1, 1960 through December 31, 1988 and who were treated at Roswell Park Cancer Institute. Twelve patients were treated for thyroid cancer, of whom nine were women. In situ breast carcinoma was diagnosed 25 and 26 years after diagnosis of thyroid cancer in two of four women treated with radioiodine. No new cancers were diagnosed in the five women treated with thyroidectomy only. Two of four women treated for thyroid cancer during adolescence with radioiodine, which is concentrated in the breast as well as other organs, developed in situ breast carcinoma. Review of a large cohort of adolescent female thyroid cancer patients treated with radioiodine is necessary to provide an accurate estimate of their risk of developing breast cancer. These patients must remain under medical surveillance throughout their lifetimes to facilitate prompt diagnosis of and early intervention for new conditions, such as the occurrence of breast cancer. © 1995 Wiley-Liss, Inc.  相似文献   
1000.
Objective: Our purpose was to evaluate the contribution of intraoperative radiation therapy in the management of recurrent cervical cancer.Study design: Twenty-two patients were treated with electron beam intraoperative radiation therapy for recurrent cervical cancers that were confined to the pelvis but were too extensive to be adequately treated by radical surgery alone. All patients underwent extensive surgical dissection for exposure and maximal tumor resection. Doses of intraoperative radiation therapy ranged from 14 to 27.8 Gy (median 22 Gy). Twelve patients received intraoperative radiation therapy to address gross residual disease, and 10 patients were treated for microscopically positive or close surgical margins.Results: The five-year disease-specific survival and local control rates were 43% and 48%, respectively. There were trends toward better local control and disease-specific survival in patients with microscopic residual disease compared with those with gross residual disease. Seven patients had peripheral neuropathy related to treatment, and four of these cases resolved.Conclusion: In carefully selected cases intraoperative radiation therapy contributes to radical salvage of patients with recurrent cervical cancer involving the pelvic wall.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号