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   4816971篇
  免费   368065篇
  国内免费   14426篇
耳鼻咽喉   67575篇
儿科学   155226篇
妇产科学   128619篇
基础医学   727401篇
口腔科学   133221篇
临床医学   442287篇
内科学   873753篇
皮肤病学   117048篇
神经病学   396276篇
特种医学   186135篇
外国民族医学   741篇
外科学   726723篇
综合类   134560篇
现状与发展   24篇
一般理论   2843篇
预防医学   406680篇
眼科学   114005篇
药学   338580篇
  31篇
中国医学   12247篇
肿瘤学   235487篇
  2021年   56346篇
  2019年   58873篇
  2018年   75246篇
  2017年   57609篇
  2016年   63758篇
  2015年   76347篇
  2014年   110821篇
  2013年   176076篇
  2012年   138155篇
  2011年   146805篇
  2010年   130274篇
  2009年   130050篇
  2008年   132819篇
  2007年   142699篇
  2006年   149981篇
  2005年   145125篇
  2004年   144948篇
  2003年   134758篇
  2002年   124100篇
  2001年   177371篇
  2000年   173288篇
  1999年   157747篇
  1998年   73223篇
  1997年   68546篇
  1996年   66927篇
  1995年   62148篇
  1994年   56344篇
  1993年   52328篇
  1992年   116001篇
  1991年   112491篇
  1990年   108449篇
  1989年   105841篇
  1988年   97783篇
  1987年   95958篇
  1986年   90842篇
  1985年   88849篇
  1984年   73107篇
  1983年   65146篇
  1982年   50179篇
  1981年   46705篇
  1980年   43873篇
  1979年   65331篇
  1978年   52118篇
  1977年   45407篇
  1976年   42529篇
  1975年   43567篇
  1974年   48865篇
  1973年   47037篇
  1972年   44380篇
  1971年   41358篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.  相似文献   
993.
Despite a widely held belief that the use of emollients prior to broad-band UVB irradiation accelerates clearance of psoriasis, only one single-blind controlled study exists in support of this. No similar study has been carried out with photochemotherapy (PUVA) or narrow-band UVB (311–313 nm) phototherapy. As some emollients absorb UV radiation, and thereby inhibit psoriasis clearance, there is a need to identify emollients suitable for pre-irradiation use. Coconut oil may be useful in this respect. In two randomized groups of patients with chronic plaque psoriasis undergoing either routine PUVA(n=14) or narrow-band UVB phototherapy (n=15), a single-blind controlled (half-body) study was undertaken to assess the died of pre-irradiation application of coconut oil. Patients were given PUVA twice weekly, or TL-01 therapy thrice weekly. The initial UV dose was 70% of previously determined minimal phototoxic (MPD) or minimal erythema doses (MED), with 40% incremental steps at each visit (reduced if adverse effects occurred). Psoriasis severity was scored on each side after every three treatments. No significant acceleration of psoriasis clearance was seen in either group. We do not, therefore, recommend the routine use of emollients prior to PUVA or TL-01 therapy when using near erythemogenic irradiation regimens.  相似文献   
994.
995.
ABSTRACT. This paper describes the method and results of a survey of aggressive behaviour amongst people with learning difficulties. The study was confined to a single health district in the South Western Region of the UK with a general population of about 370000. At the time of the survey, the Handicap Register for the district recorded 1362 people as having a learning difFiculty. The overall prevalence of aggressive behaviour amongst people with learning difficulties for whom base population data was available was 17.6%. The lowest rate was identified amongst day facilities (9.7 %) and the highest in hospitals within the district (38.2%). The prevalence rate amongst those attending schools for children with severe learning difSculties was 12.6%. Proportionately more males than females were reported to present problems of aggressive behaviour. The gender difference appeared to be largely accounted for by the disproportionate number of men identified within day facilities. There was no significant evidence of an association between the person's gender and the presence aggressive behaviour within schools or hospitals. The results indicated that, although physical and verbal aggression were the most frequently reponed behaviours, many of the sample were also said to engage in other forms of challenging behaviour, particularly self-injurious, ritualistic, stereotypical and withdrawn behaviour. The risk of a serious or very serious injury to another person was very low; 0.7% or six people with learning difiSculties firom the district were reponed to be currently presenting such a risk. Similarly, only 2% of the base population (n=18) were reponed to be extremely difficult to manage. The implications of the findings are discussed.  相似文献   
996.
Corpus cavernosography in a patient with erectile dysfunction revealed absence of communication between the 2 cavernous bodies. No similar case was found in a review of 100 consecutive cavernosograms or in the literature. The abnormality may be a source of error in pressure recordings or in intravenous injection of pharmaceutical agents.  相似文献   
997.
Gallstone dissolution   总被引:2,自引:0,他引:2  
Many methods are available for gallstone dissolution, including oral bile salts; cholesterol solvents such as mono-octanoin or methyl tert-butyl either; and calcium or pigment solvents such as EDTA and polysorbate. Which of these approaches will be appropriate for an individual patient depends on the type of stones; whether they are in the gallbladder or the bile ducts; whether access to the biliary tree is available; the patient's age and general medical condition; and the availability of necessary expertise. In the US, both chenodeoxycholate and ursodeoxycholate are now available. Ursodeoxycholate is more expensive but appears to produce fewer side effects and may be more efficacious. These agents are most effective in thin women with small floating, radiolucent cholesterol stones in a functioning gallbladder. Only about half of the small subset of patients will experience partial or complete dissolution of stones within a year. Stone recurrence and the potential toxicity of long-term therapy are problems with this approach. Therefore, for most patients, cholecystectomy, either in the traditional fashion or using a laparoscopic approach (see article later in this issue by Gadacz et al), is the most cost-effective and perhaps the safest option. Intragallbladder instillation of methyl tert-butyl ether probably will be applicable only to a small subset of patients, and treatment is likely to be followed by a high recurrence rate. In patients with retained common duct cholesterol stones and access to the biliary tree, mono-octanoin therapy is advantageous in that it can be initiated as soon as cholangiography demonstrates no extravasation. In properly selected patients, a 90% success rate with this technique can be expected within 7 days.  相似文献   
998.
On the basis of the experience with treatment of more than 500 patients with sigmoid and rectal cancer, the informative value of the instrumental methods of investigation used for more precise definition of a stage of the disease is analysed. A scheme for rational examination of the patients is suggested.  相似文献   
999.
Patients on long-term haemodialysis suffer from dialysis arthropathy due to the deposition of dialysis amyloid. We investigated the use of 99Tc-labelled methylene diphosphonate bone scans in 17 patients as a possible in vivo diagnostic technique. In most clinically affected joints, with the exception of shoulders and hands, there was increased radioisotope uptake consistent with uptake by periarticular bone. In addition, we describe intense soft-tissue uptake around some clinically affected large joints. In contrast, control groups of patients on haemodialysis without arthropathy and patients without renal failure did not have increased uptake. A semi-quantitative scale of uptake was devised, and the following correlations were significant: pain perception and isotope uptake score in the ankles and feet, and the number of radiological lesions and isotope uptake scores in the wrists and knees. The following sites where the radioisotope might bind in the affected joints are proposed: amyloid deposits, areas of soft-tissue calcification, or areas of increased bone turnover. It is concluded that whereas the scanning technique cannot make a definite diagnosis of amyloid and, therefore, cannot be expected to supersede histological diagnosis, it is a useful adjuvant investigation, of particular importance in those patients unable or unwilling to undergo biopsy.  相似文献   
1000.
Eleven patients with lunatomalacia were treated by excision of the lunate and instillation of liquid silicone. The silicone vulcanised and formed an in-situ molded prosthesis. The patients were reexamined after a mean of 7.1 years. Four patients were pain-free and two had pain only at work; three had not been improved by the operation and two had undergone arthrodesis. The patients with good results all belonged to group IV pre-operatively. Surprisingly, no patient showed any sign of silicone synovitis, although all the prostheses except one had either fractured or deformed. The reasons for this are discussed and the indications for the operation established.  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