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   2606296篇
  免费   203662篇
  国内免费   6403篇
耳鼻咽喉   38075篇
儿科学   82752篇
妇产科学   67804篇
基础医学   370955篇
口腔科学   67922篇
临床医学   246335篇
内科学   519786篇
皮肤病学   61882篇
神经病学   207155篇
特种医学   99974篇
外国民族医学   489篇
外科学   404334篇
综合类   49516篇
现状与发展   89篇
一般理论   914篇
预防医学   196345篇
眼科学   60679篇
药学   187871篇
  11篇
中国医学   6095篇
肿瘤学   147378篇
  2021年   25598篇
  2019年   24188篇
  2018年   36658篇
  2017年   28950篇
  2016年   32816篇
  2015年   37212篇
  2014年   54485篇
  2013年   73850篇
  2012年   89903篇
  2011年   94423篇
  2010年   61732篇
  2009年   61254篇
  2008年   87145篇
  2007年   90568篇
  2006年   92728篇
  2005年   87563篇
  2004年   82793篇
  2003年   78422篇
  2002年   75479篇
  2001年   115072篇
  2000年   116923篇
  1999年   98494篇
  1998年   30937篇
  1997年   27229篇
  1996年   27419篇
  1995年   25939篇
  1994年   22975篇
  1993年   21428篇
  1992年   74199篇
  1991年   72318篇
  1990年   70186篇
  1989年   67472篇
  1988年   61943篇
  1987年   60570篇
  1986年   56636篇
  1985年   54214篇
  1984年   40203篇
  1983年   34215篇
  1982年   20557篇
  1979年   36463篇
  1978年   26203篇
  1977年   21835篇
  1976年   20791篇
  1975年   22260篇
  1974年   26580篇
  1973年   25241篇
  1972年   23699篇
  1971年   22342篇
  1970年   20626篇
  1969年   19523篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Neisseria meningitidis group B (MenB) strains isolated from 1976 to 1987 in Finland in 339 patients with invasive infection were sero/subtyped by whole cell enzyme immunoassay using monoclonal antibodies to class 1 and 2/3 outer membrane proteins. 66.7% of the strains could be serotyped (class 2/3) and 70.2% subtyped (class 1). No single phenotype was clearly predominant. The most common serotypes were 4 (18.6%) and 14 (17.4%) and the most common subtypes P1.16 (20.1%) and P1.2 (12.1%). The Norwegian phenotype B:15:P1.16 was seen only rarely (a total of 18 strains). Strains from Northern Finland did not differ from those from Southern Finland: no single phenotype caused the slight increase seen in the incidence of MenB infections in the end of 1970s in the North.  相似文献   
992.
993.
In preventive medicine and occupational health, decision-makers face uncertainty, divergent opinions, and varying needs. In the Swiss aluminum industry, screening for industrial fluorosis illustrates how decision analysis and cost-effectiveness analysis can provide rational and explicit models of decision-making in such contexts. Data on fluoride-exposed potroom workers are used to compare the cost-effectiveness of two strategies: mass screening of fluorosis versus individual detection of the disease on the basis of the worker's symptoms. A decision-analysis and a sensitivity analysis are performed to assess the impact of the screening program for different levels of expected prevalence of the disease. The optimal decision, in economic terms, is the one that minimizes the pension and screening-related costs and maximizes the number of years of full working capacity. Swiss data suggest that a diagnosis of clinical fluorosis is unlikely before 10 years of exposure to fluoride. Between 10 and 30 years of exposure to fluoride, mass screening may be more cost-effective than individual detection of the disease, even when the expected prevalence of the disease in a given industrial setting is less than 10%.  相似文献   
994.
Biopharmaceutic comparison is achieved between commercialized capsules of vinburnine and drops dosage form intended for geriatric pharmacotherapy. Drug bioavailability of vinburnine seems saved, if not significantly increased by the new formulation, in spite of the very important, and well known interindividual variations of vincamine drug products. Only the absorption rate seems statistically increased by drops.  相似文献   
995.
996.
Uveal melanoma radiation. 125I brachytherapy versus helium ion irradiation   总被引:4,自引:0,他引:4  
The optimum radiation therapy for uveal melanoma is uncertain. Both helium ion irradiation and 125I brachytherapy have been used to treat this neoplasm. This investigation analyzed the control and complication rates of uveal melanomas treated with helium ions of 125I plaques. In both a retrospective and a prospective dynamically balanced study, the control rates appeared to be similar. There were more posterior segment complications after 125I plaques and more anterior segment complications, including neovascular glaucoma, after helium ion irradiation. The follow-up period is too short to draw definitive conclusions on the radiation complications. Overall, approximately 89% of eyes were retained and less than 4% of treated eyes were removed because of failure to control the tumor.  相似文献   
997.
Two patients with a history of glaucoma and a propensity for uveitis developed ciliochoroidal effusions following Nd:YAG laser posterior capsulotomy. Both patients experienced a waxing and waning course with eventual resolution of symptoms after a steroid regimen. The ciliochoroidal effusions were presumed to be secondary to uveitis induced by the YAG laser surgery. The role of glaucoma, previous surgeries, and an open posterior capsule is uncertain but may have predisposed these patients to ciliochoroidal detachment. We advise caution in performing YAG posterior capsulotomy in patients with glaucoma and a known propensity for uveitis.  相似文献   
998.
St. Jude Medical valve replacement was performed in 1,039 patients; 320 had aortic (AVR), 543 mitral (MVR), and 176 had double valve replacement (DVR). There were 44(4.2%) early deaths. Follow-up extended in 995 patients from 10 to 130 months, with a cumulative period of 2,730 patients-years. The overall survival rates of AVR, MVR, and DVR patients at 10 years were 60.5%, 89.6%, 90.3% respectively. The linearized incidences of valve thrombosis, thromboembolism, anticoagulation-related hemorrhage, prosthetic valve endocarditis, and significant hemolysis were as follows: 0.11%/pt-yr, 1.33%/pt-yr, 0.04%/pt-yr, 0.18%/pt-yr, and 0.11%/pt-yr, respectively. There were no structural failure after 10 years follow-up. Reoperation (explant and re-replacement or suture repair) was required in 10 patients. Seven of them had periprosthetic leakage, 2 had valve thrombosis, and one underwent reoperation because of a technical error. Actuarially over 98% of patients were free of valve-related mortality at 10 years. St. Jude Medical valve is an excellent alternative for use in the surgical treatment of valvular heart disease.  相似文献   
999.
The first phase of data bank of hazard (DBH) of polymers has been developed and put into operation on the basis of CM-computers. DBH is a factographical computer-based system of data collection, storage and processing aimed at complex assessment of material and substance hazard. Systems approach to the analysis of material's characteristics serves as a methodological basis. DBH data base includes a set of input and output documents according to 5 types of biological hazards involving sanitary and chemical surveillance, fire hazard and thermodestruction, the data on material's microbiologic resistance, their electrifying and toxicohygienic characteristics. DUAMC-3 operational system, DUAMC. DBH software are included into the system of data banks of materials' technological properties.  相似文献   
1000.
A sample of 110 consecutive first admission young schizophrenic patients treated between 1964 and 1967 was rediagnosed in 1981. Among 92 survivors, 27 could be labelled as paraphrenics. From information available at inception 97 variables were coded covering such areas as personality, previous disturbances, age and type of onset, and symptoms around admission. Sixty-three out of 97 variables were hypothesized to differentiate, at admission, future paraphrenics from the rest of the sample. Paraphrenics were found to have had less contact disturbance, better self-esteem, less neurotic symptoms in adolescence and childhood, and less complaints of unhappiness when growing up. They had more regressive and paranoid symptoms at admission, were older at onset of the disease, which was more acute, more often connected with precipitating events, and confusion. Certain non-regressive symptoms such as brooding, anhedonia and concentration difficulties were less common. A discriminant analysis yielded a proportion of correct predictions = 0.64 (p less than 0.05). The results are in accordance with the theory of more favourable energetic and organizational capacity in paranoid schizophrenics as compared with non-paranoids.  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