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   2092篇
  免费   112篇
  国内免费   5篇
耳鼻咽喉   6篇
儿科学   92篇
妇产科学   70篇
基础医学   167篇
口腔科学   192篇
临床医学   124篇
内科学   686篇
皮肤病学   113篇
神经病学   146篇
特种医学   49篇
外科学   237篇
综合类   44篇
一般理论   2篇
预防医学   68篇
眼科学   27篇
药学   93篇
中国医学   7篇
肿瘤学   86篇
  2023年   10篇
  2022年   30篇
  2021年   41篇
  2020年   26篇
  2019年   33篇
  2018年   34篇
  2017年   36篇
  2016年   41篇
  2015年   63篇
  2014年   75篇
  2013年   98篇
  2012年   130篇
  2011年   140篇
  2010年   97篇
  2009年   72篇
  2008年   90篇
  2007年   93篇
  2006年   96篇
  2005年   100篇
  2004年   115篇
  2003年   85篇
  2002年   62篇
  2001年   49篇
  2000年   67篇
  1999年   46篇
  1998年   20篇
  1997年   13篇
  1996年   13篇
  1995年   8篇
  1994年   14篇
  1993年   6篇
  1992年   32篇
  1991年   32篇
  1990年   47篇
  1989年   28篇
  1988年   24篇
  1987年   29篇
  1986年   21篇
  1985年   19篇
  1984年   18篇
  1983年   11篇
  1982年   19篇
  1981年   7篇
  1979年   15篇
  1978年   12篇
  1977年   13篇
  1975年   11篇
  1973年   9篇
  1972年   8篇
  1969年   18篇
排序方式: 共有2209条查询结果,搜索用时 0 毫秒
1.
2.
Endoscopic sclerotherapy in the treatment of gastric varices   总被引:4,自引:0,他引:4  
Of 309 patients with portal hypertension, gastric varices were found in 48 (16 per cent). While the majority (88 per cent) of the patients had gastric varices in association with oesophageal varices, 6 (12 per cent) patients had 'isolated' gastric varices. Gastric varices were seen significantly (P less than 0.01) more often with grade 4 than with grade 3 varices. In 11 (28 per cent) of the 40 patients who completed sclerotherapy for oesophageal varices, gastric varices disappeared concurrently on eradication of oesophageal varices or during the following 6 months. Of the initial five patients with gastric varices who received direct intravariceal injections, four rebled; this technique was therefore replaced by combination (paravariceal + intravariceal) gastric variceal sclerotherapy. Emergency combination sclerotherapy successfully controlled bleeding from gastric varices in six of the eight treated patients. Thirty-two patients entered a programme of elective combination gastric variceal sclerotherapy. Variceal obliteration was achieved in 12 cases (38 per cent) and reduction in size was noted in another 7 patients (22 per cent) after a minimum of four courses. There were 11 (23 per cent) deaths, 8 due to uncontrolled bleeding from gastric varices and 3 due to hepatic coma. The other complications of gastric variceal sclerotherapy were minor and included retrosternal pain, fever and dysphagia. It is concluded that gastric varices often coexist with large oesophageal varices. If they persist for 6 months after eradication of oesophageal varices, a combination of paravariceal and intravariceal sclerotherapy should be attempted for their obliteration.  相似文献   
3.
4.
5.
The RFP-TM protein family was first described in Caenorhabditis elegans as hypothetical transmembrane proteins containing a conserved 350-400 amino acid domain including the invariant peptide motif RFP. The VMD2 gene underlying Best disease was shown to represent the first human member of the RFP-TM protein family. More than 97% of the disease-causing mutations are located in the N-terminal RFP-TM domain implying important functional properties. Here, we have identified three novel VMD2-related human genes (VMD2L1, VMD2L2 and VMD2L3) demonstrating a high degree of conservation in their respective RFP-TM domains. Each of the VMD2-like proteins has a unique C-terminus that lack similarity to other proteins or motifs. By FISH analysis, VMD2L1 was localised to chromosome 19p13.2-p13.12, VMD2L2 to 1p32.3-p33 and VMD2L3 to 12q14.2-q15. RT-PCR analyses revealed tissue-restricted expression of the three genes with both VMD2L1 and VMD2L2 abundantly transcribed in colon. VMD2L1 is present in the retinal pigment epithelium while VMD2L3 shows predominant expression in skeletal muscle.  相似文献   
6.
A murine TSPY     
Sequences homologous to human and bovine TSPY were isolated from M. musculus testicular cDNA, and a nearly full-length gene was polymerase chain reaction (PCR) amplified from mouse genomic DNA. This gene is apparently non-functional. Contrary to the situation encountered in species along the primate and artiodactyl lineages, in which TSPY is moderately repetitive, murine Tspy appears to be single copy. Murine Tspy is located on Yp, i.e. in the same syntenic group as in man. Sequence comparisons of murine, human and bovine TSPY exons suggest that TSPY became non-functional during rodent evolution.  相似文献   
7.
Poly (ADP-ribose) polymerase (PARP) is an abundant chromatin associated protein important in DNA repair, maintenance of chromosomal stability and programmed cell death. Here we report that an increase in caspase 3-activity and cleavage of PARP serves as an early execution phase signal in human neuroblastoma. Human neuroblastoma SK-N-SH cells were exposed to a protein kinase inhibitor, staurosporine, or a topoisomerase II inhibitor, etoposide, at various concentrations and time points. Cells exposed to staurosporine (0.1 microM) for 30 min showed an increase in caspase 3-activity and by 1 h an increase in PARP 116-kDa band and an 85-kDa cleavage product, which further increased in density with time after treatment. Quantitative analysis for condensed chromatin material using bisbenzimide, and DNA fragmentation enzyme immunoassays showed a significant increase in apoptosis 5 h after staurosporine treatment. This was further confirmed with a Klenow fragment of DNA polymerase I assay which primarily detects single-stranded DNA breaks. A significant decrease in mitochondrial metabolism occurred within 8-12 h after treatment. Studies using Trypan Blue exclusion, and lactic dehydrogenase (LDH) release revealed a significant increase in membrane permeability 8 h after staurosporine (0.1 microM) or etoposide (10 microM) treatments. Cleavage of lamin B1, a protein important in maintaining the nuclear envelope integrity was observed 12 h after staurosporine treatment. Our results show that activation of caspase 3 followed by PARP cleavage occur at much earlier time point than any other morphological or biochemical parameters of apoptosis or cytotoxicity.  相似文献   
8.
Open ring enhancement is considered highly specific for atypical demyelination. In this report we present a patient with a history of headache, ataxia and sensory disturbances in the lower extremities. A cranial MRI scan showed a large frontal lesion with mass effect, midline shift and with open ring enhancement. These findings are characteristics of tumefactive multiple sclerosis. Such lesions can be confused with neoplasms and abscesses. Open ring enhancement may help in differentiating atypical demyelination from a neoplasm or an abscess.  相似文献   
9.
Left atrial appendage (LAA) has unique anatomical and physiological properties, which make it a common site for thrombus formation in many cardiovascular and systemic diseases. Assessment of LAA for thrombus thus becomes important in many clinical situations and two-dimensional transesophageal echocardiography (2D TEE), which allows excellent quality images of LAA because of its close proximity to esophagus is routinely used for this purpose. However, it is a semiinvasive procedure, requires more time and involves some degree of patient discomfort. With some training and experience, two-dimensional transthoracic echocardiography (2D TTE) can visualize LAA in most patients with good acoustic windows. A disadvantage of both 2D TTE and 2D TEE is that they provide only a thin slice or section of cardiac structures at any given time limiting their utility in comprehensively assessing the LAA for thrombus. On the other hand, live/real time three-dimensional (3D) TTE overcomes this limitation of both 2D TTE and 2D TEE because of its ability to encompass whole of the LAA in three-dimensions in the acquired data set, which can then be cropped and sectioned systematically at any desired angulation to more definitively look for clot. 3D TTE is also useful in differentiating a clot from pectinate muscles in the LAA, which can mimic a thrombus resulting in patient mismanagement. In addition, 3D TTE is helpful in sectioning a clot for lysis, which has implications in clot resolution. We reviewed the existing literature comparing the relative advantages and disadvantages of 3D TTE versus 2D TEE and found that in patients with good acoustic windows 3D TTE had similar efficacy for detecting LAA thrombus. (Echocardiography 2012;29:112-116)  相似文献   
10.
Cardiomyopathy refers to a set of diseases that are characterized by myocardial dysfunction. Classically, two-dimensional echocardiography has been used in the diagnosis of these disorders and to help guide their management. Three-dimensional transthoracic echocardiography is now increasingly being used in the diagnosis, management, and prognostication of intrinsic cardiomyopathies. In this article, we summarize the available data on the use of three-dimensional transthoracic echocardiography in various forms of intrinsic cardiomyopathy as well as some of its advantages over traditional two-dimensional transthoracic echocardiography. (Echocardiography 2012;29:76-87)  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