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   238207篇
  免费   11317篇
  国内免费   428篇
耳鼻咽喉   3088篇
儿科学   7368篇
妇产科学   4786篇
基础医学   34245篇
口腔科学   5364篇
临床医学   18958篇
内科学   52896篇
皮肤病学   6262篇
神经病学   21200篇
特种医学   7250篇
外国民族医学   101篇
外科学   29608篇
综合类   999篇
一般理论   62篇
预防医学   21608篇
眼科学   4590篇
药学   16663篇
中国医学   704篇
肿瘤学   14200篇
  2023年   1260篇
  2022年   884篇
  2021年   3563篇
  2020年   2115篇
  2019年   3970篇
  2018年   7549篇
  2017年   4945篇
  2016年   4941篇
  2015年   5547篇
  2014年   5846篇
  2013年   9368篇
  2012年   16296篇
  2011年   16234篇
  2010年   8125篇
  2009年   6087篇
  2008年   14011篇
  2007年   14944篇
  2006年   13803篇
  2005年   13684篇
  2004年   12831篇
  2003年   11720篇
  2002年   11121篇
  2001年   6199篇
  2000年   6277篇
  1999年   5601篇
  1998年   976篇
  1997年   794篇
  1996年   751篇
  1995年   683篇
  1992年   3233篇
  1991年   2895篇
  1990年   2771篇
  1989年   2520篇
  1988年   2394篇
  1987年   2216篇
  1986年   2106篇
  1985年   1891篇
  1984年   1406篇
  1983年   1198篇
  1979年   1210篇
  1978年   848篇
  1977年   798篇
  1975年   806篇
  1974年   986篇
  1973年   1004篇
  1972年   941篇
  1971年   929篇
  1970年   862篇
  1969年   907篇
  1968年   789篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
81.
We report a prevalence study of the best visual acuity in the affected eye of 100 selected patients with herpetic keratitis seen during a two-year period. Sixty-two patients retained an acuity of 6/9 or better without requiring penetrating keratoplasty (PK). The prevalence of reduced visual acuity severe enough to warrant PK was 33%. Patients requiring PK for whom full clinical records were available suffered a mean of 6.8 episodes of keratitis. In this group of patients the vision of 18 fell from 6/6 to 6/60 over a mean period of 8.5 years. Once visual acuity was permanently reduced to 6/12, 78% of patients proceeded to lose vision to 6/60. Unilateral visual impairment occurs in at least a third of patients with severe herpetic keratitis. Once vision falls permanently to 6/12, the long-term prognosis for vision appears to be poor.  相似文献   
82.
83.
A retrospective study of 232 bladder tumours with minimum follow-up 5 years is presented. The carcinoma was superficial in 66%, muscle-invasive in 31% and could not be staged in 3%. Primary treatment was mainly transurethral resection for superficial tumour, but was cystectomy or radiotherapy in 22 of 29 T1 G3. Of the superficial tumours, 71% recurred. Progression to higher T stage occurred in 15% of Ta and 29% of T1 tumours, and half of these patients died of bladder cancer. The corrected 5-year survival rates in grades 1, 2A, 2B and 3-4 were 96, 84, 64 and 43%, and in stages Ta, T1, T2 and T3 they were 94, 69, 40 and 31%. All patients with T4 tumour died within 4 years. Among the 45 patients with 40 Gy irradiation + cystectomy, the corrected 5-year survival rate was 83% in superficial and 64% in muscle-invasive tumours, and among the 38 with radical radiotherapy the rates in T1-3 were 46, 36 and 13%. Transurethral resection was successful in most Ta cases. Most T1 tumours were, like T2-4, of higher grade than Ta. Prognosis was worse in T1 than in Ta. After progression to muscle-invasive disease, even during close follow-up the outlook was poor, as poor as for patients with primary muscle-invasive disease.  相似文献   
84.
This study presents the result of 12–21 years' follow-up in a group of children with neonatal urinary tract infection (onset within 1 month after birth) in whom early renal growth retardation was noted without concomitant classical renal scarring. In all cases the neonatal infection was diagnosed and treated within a few days of onset and the patients were closely supervised thereafter. Renal length, parenchymal thickness and area were measured at urography. At first follow-up (22 children, mean age 4.1 years) a significant reduction of renal parenchymal thickness was noted. Long-term follow-up (18 patients, mean age 17 years) demonstrated a normalization of renal size in the entire group, although less complete in the subgroup with reflux. There were two major findings in the present study. Firstly, renal growth retardation was seen after neonatal infection, both with and without reflux. Secondly, normalization of renal size in previously small kidneys was demonstrated, suggesting that growth retardation can be a reversible phenomenon. The tendency for such normalization was slightly more marked in children without reflux. Reduction of parenchymal thickness without calyceal deformity, therefore, does not necessarily mean irreversible damage, and differentiation between permanent scarring and temporary growth retardation can thus only be made at later follow-up, possibly not until after puberty. The demonstration of renal growth retardation in spite of early diagnosis and treatment emphasizes the great vulnerability of the kidney in the newborn.  相似文献   
85.
In establishing the liability of optometrists for negligence the courts have applied the same standard of care that is imposed upon other health care professionals, holding that optometrists must employ the minimum degree of skill, care and learning that is ordinarily exhibited by members of the profession who are in good standing. The leading cases establishing this standard have involved glaucoma, retinal detachment, and intraocular tumors. Optometrists have also been held liable under product liability law for injuries caused by ophthalmic lenses, which illustrates the trend toward strict liability. Other cases have involved the doctrine of informed consent.  相似文献   
86.
In open chest dogs myocardial ischemia was induced by formation of an occlusive thrombus in the left anterior circumflex artery (LCX). Reperfusion of the LCX was achieved by infusion of the fibrin specific recombinant single-chain urokinase-type plasminogen activator (r-scu-PA). The myocardial salvage by r-scu-PA alone and in combination with the epoprostenol (prostacyclin) analog taprostene (CG 4203) was compared. There were four experimental groups: group 1 (n = 4) did not receive any treatment after LCX thrombosis; in group 2 (n = 9) at 100 min after LCX thrombosis r-scu-PA (20 micrograms.kg-1.min-1 i.v. for 30 min) was infused; in groups 3 and 4 treatment with taprostene started concomitantly with r-scu-PA infusion. The taprostene infusions lasted for 120 min and the doses were 0.1 microgram.kg-1.min-1 in group 3 (n = 6) and 0.215 microgram.kg-1.min-1 in group 4 (n = 6). Time to r-scu-PA-induced recanalisation ranged from 18-22 min with no significant difference between groups 2-4. Percent of left ventricle at risk did not differ between the groups. Infarct size as percent of the risk zone was 48.3 +/- 7.7 in group 1, 25.3 +/- 3.7 in group 2, 21.3 +/- 6.5 in group 3 and 17.1 +/- 3.5 in group 4 (p less than 0.05 groups 2-4 vs group 1). Incidence of ectopic beats increased after r-scu-PA-induced reperfusion in groups 2-4, but was significantly reduced by taprostene.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
87.
88.
A 28-year-old male patient diagnosed with Becker muscular dystrophy (BMD)-associated cardiomyopathy was successfully bridged to transplantation with the Cardiowest total artificial heart. Dramatic improvement of muscular functional status occurred following transplantation.  相似文献   
89.
Compromise of immune function in obstructive jaundice.   总被引:5,自引:0,他引:5  
  相似文献   
90.
The triphalangeal thumb-brachyectrodactyly syndrome is a very rare autosomal dominant disorder of unknown etiology characterized by an unusual pattern of limb malformations: triphalangeal thumbs and brachyectrodactyly in the hands, and ectrodactyly in the feet. In a previous report, we described the clinical and radiographical features of three related subjects with the disease and suggest that due to the unusual combination of limb defects and to its phenotypic similarity with the limb malformative pattern induced by disrupting the Hoxd13 gene in mouse, the triphalangeal thumb-brachyectrodactyly syndrome might be caused by mutations in a HOX gene. After sequencing the entire coding region of HOXD13 and the highly conserved homeodomain encoding region of HOXA13, we do not detect any deleterious mutation in any of the patients excluding that alterations at these sequences are responsible for the disease. Mutations in regulatory regions of these genes or in other genes involved in limb development might be responsible for the disease.  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