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   219879篇
  免费   20279篇
  国内免费   15469篇
耳鼻咽喉   1902篇
儿科学   2192篇
妇产科学   2979篇
基础医学   26568篇
口腔科学   3684篇
临床医学   30821篇
内科学   32938篇
皮肤病学   2227篇
神经病学   12393篇
特种医学   8223篇
外国民族医学   138篇
外科学   21724篇
综合类   35399篇
现状与发展   55篇
一般理论   19篇
预防医学   13152篇
眼科学   6698篇
药学   22722篇
  194篇
中国医学   12348篇
肿瘤学   19251篇
  2024年   698篇
  2023年   3558篇
  2022年   9198篇
  2021年   11567篇
  2020年   8596篇
  2019年   7555篇
  2018年   8034篇
  2017年   7085篇
  2016年   6655篇
  2015年   10252篇
  2014年   12549篇
  2013年   10693篇
  2012年   16003篇
  2011年   17948篇
  2010年   10514篇
  2009年   8182篇
  2008年   11113篇
  2007年   11087篇
  2006年   11227篇
  2005年   11322篇
  2004年   6999篇
  2003年   6612篇
  2002年   5498篇
  2001年   4935篇
  2000年   5344篇
  1999年   5686篇
  1998年   3524篇
  1997年   3497篇
  1996年   2813篇
  1995年   2606篇
  1994年   2142篇
  1993年   1376篇
  1992年   1891篇
  1991年   1595篇
  1990年   1290篇
  1989年   1091篇
  1988年   1014篇
  1987年   890篇
  1986年   726篇
  1985年   525篇
  1984年   336篇
  1983年   242篇
  1982年   149篇
  1981年   145篇
  1980年   111篇
  1979年   142篇
  1978年   49篇
  1977年   53篇
  1975年   57篇
  1974年   56篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
The aim of this study was to compare the survival of 116 patients with breast cancer initially treated at the First Teaching Hospital (FTH) of Norman Bethune University of Medical Sciences located in Changchun, China, from 1986 to 1991 with the survival of 886 patients seen in the “Hipital du Saint-Sacrement” (HSS) located in Quebec City, Canada, from 1987 to 1992. The clinical data were collected from the hospital records at FTH. The vital status for Chinese patients was obtained from letters of follow-up or the records of local police offices. The list of patients treated at HSS and the data for each woman were extracted from computerized data banks. The major variables studied included age at diagnosis, tumor size at pathology (cm), number of lymph nodes involved, breast surgery and adjuvant treatments of breast cancer (chemotherapy, radiotherapy, immuno-therapy). Age at diagnosis was substantially lower among patients with breast cancer seen at FTH compared to those treated at HSS (x) 1 2 =60.95,P<0.0001). The average age at diagnosis for Chinese women was about 10 years less than that for Canadian women. Patients in the two hospitals differed with respect to tumor size at pathology (x 2 2 =6.67,P=0.036). The proportion of patients with tumor size larger than 2.0 cm was larger at FTH (48.3%) than at HSS (41.1%). The mean tumor size at pathology was 3.0 cm (standard deviation =2.1 cm) for patients treated at FTH, but 2.6 cm (standard deviation=1.8 cm) for women treated at HSS (P=0.07). The proportion of women with lymph node involvement was greater at FTH (61.1 % than that at HSS (37.3%) (x 1 2 =16.51,P<0.0001). Surgical treatment of breast cancer varied considerably. In Changchun, radical mastectomy was frequent for any stage of breast cancer patients, but partial mastectomy was never performed. The situation was reversed in Quebec. The five year observed survival was 74.2% (standard error, 0.05) among breast cancer patients seen at FTH compared to 76.0% (standard error, 0.02) among women treated at HSS. After adjustments of confounding factors, there were no significant difference in five year observed survival between the patients treated at the two hospitals (P=0.42).  相似文献   
992.
Merbarone, NSC 336628, is an investigational anticancer drug with activity against experimental animal tumors including melanoma. This paper presents results of a Phase II clinical study of merbarone in patients with biopsy proven stage IV malignant melanoma without prior chemotherapy and with no evidence of CNS involvement. Thirty-five patients with median age 58 (range 27–81), with performance status 0–2 were treated with merbarone 1000 mg/m2/day for five days by intravenous continuous infusion repeated every 3 weeks. All patients (21 males and 14 females) were evaluable for toxicity. Two patients were not evaluable for response having been removed from protocol treatment due to toxicity and received other treatment during the first course of chemotherapy. Among the evaluable patients there was one complete response in a supraclavicular lymph node lasting four months and one partial liver response lasting three months. The remaining thirty-one patients were non-reponders. Of these one had a stable disease lasting 21 months. The overall objective response rate was 6% (2/35) with a 95% confidence interval of 1%–19%. Twenty-six of the 35 patients have died. The estimated median survival of the entire group was 9 months with a 95% confidence interval of six to eleven months. Renal toxicity was dose-limiting and manifested as increasing serum creatinine (54% of patients), proteinuria (51%) and hematuria (9%). One patient experienced grade 4 creatinine increase, proteinuria and acute renal failure. Other toxicities included nausea (71%), vomiting (51%), malaise (23%), weakness (20%), alopecia (17%), diarrhea (17%), anorexia (14%), transaminase (SGOT, SGPT) increase (14%), constipation (14%), alkaline phosphatase or 5nucleotidase increase (9%), and fever (9%). Hematologictoxicity (granulocytopenia, leukopenia, and anemia) was generally mild and infrequent (29%, only one patient had grade 4 granulocytopenia). Overall 9 patients (26%) had at least one grade 3 toxicity. We conclude that merbarone at this dose and schedule has detectable but minimal activity in the treatment of metastatic malignant melanoma and given the significant renal toxicity this schedule does not merit further evaluation in this disease.  相似文献   
993.
Data from analgesic clinical trials have characteristics such as ordered categorical longitudinal responses with repeated measures, delay of effect with respect to analgesic plasma concentration, and right-hand censoring of response due to remedication. In order to determine the concentration-effect relationship of such data, we propose convolving an empirical function for plasma concentration, in the form of broken lines which connect each pair of neighboring observations, with a monoexponential function, to generate effect site concentration Effect site concentration and time are used, simultaneously, as independent variables in the fit of the model for the logit of the probability of having a specific pain relief (PR) score at each time point pre-remedication, via maximum likelihood. Using corresponding effect site concentration, the probabilities of having specific PR scores post-remedication are predicted via the concentration-response relationship established. The overall (pre- and post-remedication) predictions and corresponding standard errors for the responses are then estimated. Inference of the PR scoring, using a posterior method, is proposed. An illustration using real data is used to demonstrate these methods.  相似文献   
994.
Qin L  Tang Z  Liu K  Ye S  Zhou G 《Oncology reports》1995,2(6):1175-1179
A combined polymerase chain reaction (PCR) with the enzyme HaeIII restriction analysis and DNA sequencing have been employed to study the mutations at codon 249 of p53 gene in two human hepatocellular carcinoma (HCC) cell lines and 28 surgical specimens of HCC. 14 of the 28 HCC samples (50%) had p53 point mutations at codon 249. All of point mutations at codon 249 in 10 cases sequenced are AGG to AGT transversion. p53 gene mutated more frequently in invasive HCCs than that in non-invasive HCCs. This suggested that the codon 249 was a mutational hotspot of p53 gene in human HCCs in China, and p53 mutations may be related to tumor invasiveness of human HCC.  相似文献   
995.
本研究通过测定血清阿霉素浓度,分析了原发性肝癌阿霉素肝动脉灌注(A 组)、阿霉素碘油乳化后栓塞(B 组)及阿霉素微囊栓塞化疗(C 组)后药动学变化及其临床意义。A 组药动学变化与静脉给药相似,但峰值浓度高。B 组峰浓度低,半衰期延长,显示缓释和降低血浓度的作用。C 组峰浓度不明显,表现为长时、稳定的释放,血浓度低,具有保持局部长时间高浓度作用。结果揭示了肝癌介入治疗不同给药方法疗效差异的药动学依据。  相似文献   
996.
At the turn of the last century, side by side with the infiltration of religious culture from Western countries, western medicine spread into Yantai. The religious force, headed by American Presbyterian Mission, carried out charitable activities in the process of preaching and laid down the foundation for western medicine rooted in Yantai by establishing schools, education and training followers. They cultivated local physicians by first setting up clinics which had later transformed into hospitals. These are their major measures for building bases for spreading Christianity by foreigners. The Temple Hill Hospital set up by the American physician Oscar F. Hills in Yantai was a successful example of mutual promotion of missionary and medical activities which pushed forward the spreading and development of western medicine in Yantai.  相似文献   
997.
Liu J  Zapp J  Becker H 《Planta medica》1995,61(5):453-455
From the aerial parts of Chinese Salvia miltiorrhiza Bunge a novel sesquiterpene (1), which possesses a rare substitution pattern, together with seven known abietane type diterpenes has been isolated. Structure 1 was elucidated on the basis of spectral analysis, including 2D-NMR spectroscopy, especially long range 1H-13C correlation (COLOC). At the same time royleanone, 7alpha-acetoxyroyleanone, and sugiol were identified for the first time from the roots of Salvia triloba L. f.  相似文献   
998.
Localized scleroderma is distinct from the diffuse form of scleroderma and does not show Raynaud's phenomenon and visceral involvement. The imaging features in 23 patients ranging from 2 to 17 years of age (mean 11.1 years) were reviewed. Leg length discrepancy and muscle atrophy were the most common findings (five patients), with two patients also showing modelling deformity of the fibula. One patient with lower extremity involvement showed abnormal bone marrow signals on MR. Disabling joint contracture requiring orthopedic intervention was noted in one patient. In two patients with en coup de sabre facial deformity, CT and MR scans revealed intracranial calcifications and white matter abnormality in the ipsilateral frontal lobes, with one also showing migrational abnormality. In a third patient, CT revealed white matter abnormality in the ipsilateral parietal lobe. In one patient with progressive facial hemiatrophy, CT and MR scans showed the underlying hypoplastic left maxillary antrum and cheek. Imaging studies of areas of clinical concern revealed positive findings in half our patients.  相似文献   
999.
PreliminaryevaluationofpelvicvascularbedisolationchemotherapyinthetreatmentofadvancedcervicalcarcinomaJiangSenandPostgraduate...  相似文献   
1000.
Objective: The objective of this study was to determine whether human papillomavirus (HPV) infections are involved in the development of papillomatosis lesions of the lower female genital tract.Methods: A total of 616 biopsy specimens of genital papillomatous lesions (307 nodular and 309 papular types) from 598 patients were anaylyzed for the presence of HPV DNA sequences by polymerase chain reaction (PCR). These specimens were also examined by histopathological assessment for characteristic HPV-associated cytological changes, by immunohistochemical staining for HPV-associated antigen, and by electron microscopy for the presence of virions.Results: HPV DNA sequences were found in 97.9% (140 of 143 cases) and 1.1% (1 of 91 cases) of the nodular and papular papillomatosis cases tested, respectively. In 18 patients who had both types of papillomatosis lesions, HPV DNA was invariably found only in nodular tissues. HPV-associated antigen, koilocytosis, and virions were found in 53.6% (98 of 183 cases), 70.5% (129 of 183 cases), and 5.9% (5 of 85 cases) of nodular papillomatosis lesions tested, respectively.Conclusions: These data suggest that nodular papillomatosis was closely associated with HPV infection, but that papular papillomatosis of the lower female genital tract may have an etiology other than HPV infection.  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