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   14276篇
  免费   729篇
  国内免费   53篇
耳鼻咽喉   182篇
儿科学   828篇
妇产科学   217篇
基础医学   1229篇
口腔科学   325篇
临床医学   1285篇
内科学   3811篇
皮肤病学   300篇
神经病学   733篇
特种医学   364篇
外科学   2270篇
综合类   276篇
一般理论   1篇
预防医学   724篇
眼科学   468篇
药学   870篇
中国医学   42篇
肿瘤学   1133篇
  2023年   83篇
  2022年   194篇
  2021年   470篇
  2020年   227篇
  2019年   335篇
  2018年   487篇
  2017年   267篇
  2016年   302篇
  2015年   327篇
  2014年   570篇
  2013年   644篇
  2012年   982篇
  2011年   1032篇
  2010年   576篇
  2009年   417篇
  2008年   748篇
  2007年   804篇
  2006年   768篇
  2005年   640篇
  2004年   639篇
  2003年   540篇
  2002年   551篇
  2001年   297篇
  2000年   252篇
  1999年   243篇
  1998年   130篇
  1997年   82篇
  1996年   69篇
  1995年   78篇
  1994年   45篇
  1993年   57篇
  1992年   177篇
  1991年   179篇
  1990年   177篇
  1989年   157篇
  1988年   148篇
  1987年   132篇
  1986年   114篇
  1985年   113篇
  1984年   111篇
  1983年   77篇
  1982年   57篇
  1981年   47篇
  1980年   50篇
  1979年   87篇
  1978年   41篇
  1977年   67篇
  1974年   53篇
  1972年   51篇
  1970年   44篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
In a subgroup of children with autism-spectrum like conditions symptoms seem to appear as a 'regression' (in normal development). It has been postulated that the onset of such autistic symptoms may involve an autoimmune response against the central nervous system and that the antigenic determinant could possibly be gastrointestinal in origin. It has been suggested that the presence of the measles virus and 'autistic enterocolitis' demonstrates the possibility that the MMR triple vaccine may be mediating the inflammation with possible production of antibodies against the virus containing vaccine. Such an antibody may share antigenic determinant to molecules found in the gut. We propose that this may be secretin or its receptor, found in the gut as well as in the central nervous system. The antibody response to the gut may also conceivably occur in the brain at a critical time in development. The modulation of development by secretin may be a static event possibly occurring at a specific time in early childhood development and if it involves an autoimmune response then a disruption in development may result. These hypothesized events can only occur if the MMR vaccine shares antigenic determinants that resemble secretin or any of its receptor types and remains to be studied.  相似文献   
52.
53.
The role of radiotherapy in small cell carcinoma of the lung is unsettled; however, the radiosensitivity of this neoplasm is unquestioned. The ability of radiotherapy to cure or improve patients with this disease is still undergoing study. A review of this challenging subject is presented.  相似文献   
54.
Adenosine kinase (AK) from CHO cells has been purified to homogeneity and specific antibodies to it have been raised in rabbits. Using this antibody, the presence of a specific cross-reacting protein (CRP) in cell extracts of different classes of mutants resistant to purine nucleoside analogs which are affected in AK has been investigated by the immunoblotting technique. Results of our studies show that 31 of the 32 independently selected class A AK mutants (obtained at high frequency in presence of adenosine analogs toyocamycin, tubercidin, 6-methylmercaptopurine riboside, or pyrazofurin and containing no measurable activity of AK in cell extracts) contained similar amounts of a specific CRP as seen in the parental AK+ cells. The CRP in the parental and different mutant cell lines has the same relative molecular mass as purified AK. Similar results were obtained with two mutants each of the class B and C type (selected in presence of C-nucleosides formycin A and formycin B), which are also affected in AK but show novel properties. The presence of equivalent amounts of the CRP in the vast majority of the class A mutants strongly indicates that the high frequency of those mutants in CHO cells is not a result of an epigenetic or deletion type of event, but that such mutants may contain missense types of mutations at a presumed mutational hot spot within the structural gene for adenosine kinase.  相似文献   
55.
56.
J Mehta  A Nagler  S Slavin 《The New England journal of medicine》1992,326(16):1087; author reply 1087-1087; author reply 1088
  相似文献   
57.
58.
Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain‐of‐function mutations in the regulatory (SUR2) and pore‐forming (Kir6.1) subunits of KATP channels, respectively, suggesting that channel‐blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg–1 kg–1 day–1 in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg?1 kg?1day?1 over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS.  相似文献   
59.
Genetic diversity was characterized in 20 isolates of Grapevine fanleaf virus (GFLV) recovered from naturally infected grapevine plants (Vitis vinifera) in the North of Tunisia. Viral RNAs were isolated by oligoprobe capture, and a 605 bp fragment containing a part of the viral coat protein gene was amplified by RT-PCR. Sequence variation among isolates was characterized by restriction fragment length polymorphism (RFLP) analysis and confirmed by sequencing. The GFLV infections are found as a complex mixture of closely related genomes. In further studies, RFLP analyses of virus isolates using AluI showed that GFLV populations in Tunisian vineyards consist of two restrictotypes corresponding to distinct sub-populations Sp1 and Sp2. The relative field distribution of these sub-populations showed that Sp2 was more abundant. Individual genomes were recovered by cloning the RT-PCR products. The sequences were found to vary from each other by as much as 11%. Cloning from mixed infections showed that Sp2 are also predominant.  相似文献   
60.
The above discussion on the interaction of aspirin and ACE inhibitors seems to suggest that aspirin in high doses may have adverse interaction with ACE inhibitors in patients with heart failure but the data obtained is not sufficient or conclusive to recommended omission of aspirin in patients with heart failure. This raises a query in the mind of the physician whether to use a combination or not? The role of aspirin in the early period after myocardial infarction is well established so is the role of ACE inhibitors. Hence in patients with myocardial infarction and preserved left ventricular function it would not be wrong to administer combination of ACE inhibitors and aspirin. Albeit at a lower dose. In patients with large myocardial infarction or heart failure, warfarin may be an option but still needs to be documented in large trials. As suggested long term use of aspirin after infarction is still ambiguous and may be harmful in patients with heart failure with its anticedent side effects. But long term benefits of ACE inhibitors in heart failure are well documented. Hence if a choice has to be made whether to discontinue either of the two drugs it would be preferable to stop the aspirin. To answer the issue of use of aspirin in patients with heart failure it would be essential to conduct a double blind randomized trial comparing known anti-thrombotic treatment, aspirin and anti-coagulants on mortality in patients with heart failure, especially caused by coronary artery disease. Such a trial is underway at the present and till the results are available it should be left to clinical judgement of the physician whether to administer aspirin in patients with heart failure after weighing the benefits versus risk.  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