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   333784篇
  免费   29212篇
  国内免费   7953篇
耳鼻咽喉   4154篇
儿科学   6314篇
妇产科学   5298篇
基础医学   23929篇
口腔科学   10077篇
临床医学   34333篇
内科学   38624篇
皮肤病学   4658篇
神经病学   16623篇
特种医学   9631篇
外国民族医学   49篇
外科学   32525篇
综合类   51610篇
现状与发展   32篇
一般理论   26篇
预防医学   33986篇
眼科学   4050篇
药学   30342篇
  465篇
中国医学   37669篇
肿瘤学   26554篇
  2024年   4868篇
  2023年   7727篇
  2022年   12407篇
  2021年   16177篇
  2020年   15712篇
  2019年   16219篇
  2018年   14385篇
  2017年   13339篇
  2016年   12636篇
  2015年   11923篇
  2014年   22506篇
  2013年   25221篇
  2012年   19538篇
  2011年   20761篇
  2010年   16916篇
  2009年   15066篇
  2008年   14219篇
  2007年   14663篇
  2006年   12735篇
  2005年   11010篇
  2004年   9056篇
  2003年   8103篇
  2002年   6427篇
  2001年   5493篇
  2000年   4726篇
  1999年   3779篇
  1998年   3090篇
  1997年   2704篇
  1996年   2215篇
  1995年   2061篇
  1994年   1763篇
  1993年   1475篇
  1992年   1340篇
  1991年   1219篇
  1990年   1062篇
  1989年   1000篇
  1988年   936篇
  1987年   828篇
  1986年   731篇
  1985年   2020篇
  1984年   2264篇
  1983年   1436篇
  1982年   1859篇
  1981年   1335篇
  1980年   1134篇
  1979年   1012篇
  1978年   799篇
  1977年   593篇
  1976年   740篇
  1975年   509篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Abstract The outcome of OLT for HBV-related liver disease is dependent on the prevention of allograft re-infection. Over the past decade, major advances have been made in the management of HBV transplant candidates. The advent of long-term hepatitis B immune globulin (HBIG) administration as a prophylaxis against HBV recurrence, and the introduction of new antiviral agents against HBV infection, such as lamivudine (LAM), were a major breakthrough in the management of these patients. Results of OLT for HBV infection are similar to those achieved with other indications. Pre-OLT antiviral treatment such as LAM can suppress HBV replication before OLT and thus decrease the risk of re-infection of the graft. Combination prophylaxis with LAM and HBIG after transplantation highly effectively reduces the rate of HBV re-infection, even in HBV replicative cirrhotic, patients. The optimal HBIG protocol in the LAM era is yet to be defined: dosing of HBIG, routes of administration, and possibility of stopping HBIG. Several antiviral drugs have been developed for the management of HBV infection on the graft, so outcome is currently good.  相似文献   
82.
83.
Both systemic and local therapy, for conditions of the breast and unrelated to it, may produce manuno-graphic changes. Some of these are characteristic, such as the pattern of scarring seen in reduction mammo-plasty. In many other instances, however, the changes produced overlap features commonly seen in malignancy. A knowledge of the timing, natural history and spectrum of these changes will aid mammographic interpretation.  相似文献   
84.
The referral pattern of 140 Dutch patients with oral mucosal lesions, who had been referred to a Department of Oral & Maxillofacial Surgery and Oral Pathology, shows that patients with oral mucosal lesions consult the dentist as often as the family doctor as the first source of help or information. Furthermore, family doctors were much more used to refer patients with oral mucosal disease to medical specialists rather than to the dentist or the oral and maxillofacial surgeon.  相似文献   
85.
小包装全氟丙烷气体动力学实验研究   总被引:1,自引:0,他引:1  
为检验塑料小包装全氟丙烷气体(C3F8)在不同包装和储存方法时浓度变化,将装有5~7mlC3F8的聚氯乙烯小袋,根据不同储藏温度和外包装方法随机分成四组:(1)22℃聚乙烯外包装,(2)36℃聚乙烯外包装,(3)22℃铝箔真空外包装,(4)-29℃聚乙烯外包装;每一组C3F8小袋气体存放一定时间后,应用气相色谱分析方法进行浓度测量。结果:第3组C3F8浓度最高和稳定,第2组浓度随放置时间降低最明显,第4组是临床应用气体的储藏和包装方法,其30天样本浓度和第3组相等,但放置一年时浓度降低。结果显示:塑料小包装C3F8予以铝箔真空外包装是一种可行的方法,利于C3F8运输和普及;聚乙烯外包装的C3F8,应放在-29℃保存,时间不超过一年。  相似文献   
86.
Abstract. A prospective randomized study was conducted to evaluate the impact of four different conversion protocols on graft outcome in long-term follow-up. Between January 1986 and May 1987, 128 patients with first cadaveric kidney allografts were randomized at the time of transplantation to four treatment groups of 32 patients each, to be assigned 10 weeks post-transplantation. During the first 10 weeks, all patients received triple therapy with low-dose azathioprine (Aza), cyclosporin (CyA), and methylprednisolone (MP). After 10 weeks, one group continued with triple therapy (group A) while the three other groups received different combinations of two drugs, namely, Aza and CyA (group B), Aza and MP (group C), or CyA and MP (group D). Withdrawal of MP (group B) or especially of CyA (group C) was associated with 4/29 (14%) and 10/28 (36%) acute rejection episodes, respectively, for 60 days after conversion. All rejections were mild and reversible. There were no rejections after Aza withdrawal or in the group that continued on triple therapy during the corresponding time period. The most common reason for dropping out after withdrawal, for those patients who could not continue on the originally randomized medication, was azathioprine intolerance (n= 12). Five patients were switched back to triple therapy after CyA withdrawal due to rejection. Steroid intolerance was rare and CyA in low doses was very well tolerated. At 1 year there were no statistically significant differences in graft survival between groups A, B, C, and D-81 %, 88%, 88%, and 88%, respectively-or in patient survival-88%, 88%, 88%, and 97%, respectively. For those patients continuing with the originally randomized treatment protocol, there were no differences in patient or graft survival either, the means being 91% and 89%, respectively. The most common cause of death after withdrawal was cardiovascular in nature, and there were no more fatal infections under triple drug treatment than with double drug regimens. There were no statistically significant differences in mean serum creatinine values at 1 year. The median serum creatinine values for groups A, B, C, and D were 112, 132, 133, and 133 μmol/l, respectively. At 1 year the mean CyA dose in the groups that continued with CyA was 3. 5–4. 2 mg/kg per day and CyA concentrations were equal.  相似文献   
87.
Systolic and diastolic blood pressures were measured on 254 monozygotic (MZ) and 260 dizygotic (DZ) male twin pairs, during middle age (average age 48 years) and at two later age points. Genetic and environmental components of covariation were modeled by time series. For both measures, shared environmental influences were absent and specific environmental influences were largely time-specific. Although heritability was about 0.5 at each time point, genetic variation present at middle age contributed only about 60% to that present 9 years later, the remaining 40% being new. Fifteen years later, at the third time point, no new genetic variation was evident, variation in individual differences being entirely attributable to genetic differences laid down at the two earlier ages. © 1993 Wiley-Liss, Inc.  相似文献   
88.
目的 研究臂丛神经根单发断,2根切断(不同方式联合)及3根切断后对肢体的影响,为治疗臂丛根性撕脱伤寻找更多的潜在移位神经,方法 252只SD大鼠随机分为13组:(1)第1-5组(单根神经根切断组);每组12只大鼠。分别切断C5-8T1各神经根;(2)第6-12组(2根神经根切断组);每组24只大鼠。分别切断相邻及不相邻2根神经根,即C5,6,C6,7,C7,8,C8T1,C5,7,C6,8和C7T  相似文献   
89.
Eleven healthy free-living adults (six women, five men) weighed and recorded all food and drink consumed and collected all urine for two non-consecutive 7-day periods whilst eating their usual diet (Period 1) and attempting to reduce salt intake (Period 2). Bread (including pitta bread) provided on average a quarter of total Na intake of subjects in Period 1 so that wholemeal bread made without added salt was made available in Period 2. All subjects achieved substantial reductions (mean 65%) in Na intake in Period 2 with no change in K intake so that the Na:K molar ratio fell from 1.3 to 0.5. Urinary Na output closely followed intakes and there was a large increase (mean 11.2 μg/d) in aldosterone excretion with a non-significant increase in K output. Simple linear relationships which allow prediction of Na and K intake from the more easily measured urinary output were derived.  相似文献   
90.
Abstract: Lipid peroxidation, measured by malonyldial-dehyde (MDA) and vitamin E in red blood cells (RBC) and plasma, was investigated in 25 hemodialysis (HD) patients before and after 6 months rhEPO therapy. RBC-MDA was significantly elevated, but plasma MDA was in the reference range. After recombinant human erythro-poietin (rhEPO) treatment, the MDA level was significantly decreased in both compartments. Marked vitamin E deficiency was established in RBC as well as in plasma. rhEPO therapy restored vitamin E levels in both compartments. Our data suggest a possible positive rhEPO-antioxidant effect in HD patients.  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