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   27680篇
  免费   3239篇
  国内免费   1844篇
耳鼻咽喉   175篇
儿科学   310篇
妇产科学   243篇
基础医学   3066篇
口腔科学   636篇
临床医学   3905篇
内科学   3656篇
皮肤病学   303篇
神经病学   1359篇
特种医学   942篇
外国民族医学   23篇
外科学   2680篇
综合类   4941篇
现状与发展   5篇
一般理论   3篇
预防医学   2232篇
眼科学   672篇
药学   2963篇
  57篇
中国医学   2307篇
肿瘤学   2285篇
  2024年   590篇
  2023年   863篇
  2022年   1615篇
  2021年   1863篇
  2020年   1518篇
  2019年   1247篇
  2018年   1123篇
  2017年   1100篇
  2016年   1027篇
  2015年   1472篇
  2014年   1671篇
  2013年   1589篇
  2012年   1986篇
  2011年   2210篇
  2010年   1454篇
  2009年   1260篇
  2008年   1395篇
  2007年   1285篇
  2006年   1207篇
  2005年   1140篇
  2004年   713篇
  2003年   684篇
  2002年   569篇
  2001年   409篇
  2000年   420篇
  1999年   438篇
  1998年   260篇
  1997年   273篇
  1996年   169篇
  1995年   177篇
  1994年   150篇
  1993年   91篇
  1992年   105篇
  1991年   87篇
  1990年   99篇
  1989年   73篇
  1988年   90篇
  1987年   54篇
  1986年   48篇
  1985年   32篇
  1984年   13篇
  1983年   15篇
  1981年   13篇
  1979年   19篇
  1977年   10篇
  1975年   11篇
  1974年   10篇
  1973年   15篇
  1969年   14篇
  1966年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
中医外治法是中医学的重要组成部分,中药经皮肤或黏膜吸收后直达病所,可避免肝脏首过效应。晚期肿瘤患者正气已虚,脾胃吸收能力减弱,中药外治法更具有优势,具有副作用小、起效快、方便的特点。农村肿瘤发病率逐年升高,经济差也导致农村肿瘤防治形势更加严峻。伴随着新一代的化疗药以及靶向治疗方法的不断涌现,为肿瘤防治带来了曙光,但由此带来的不良反应,也给患者治疗带来了挑战,而其高昂的价格也令广大基层群众望而却步,"简、便、效、廉"的中医外治肿瘤技术能够满足部分肿瘤防治的需求。  相似文献   
62.
Vulnerable areas of atherosclerotic plaques often contain lipid-laden macrophages and display matrix metalloproteinase activity. We hypothesized that reactive oxygen species released by macrophage-derived foam cells could trigger activation of latent proforms of metalloproteinases in the vascular interstitium. We showed that in vivo generated macrophage foam cells produce superoxide, nitric oxide, and hydrogen peroxide after isolation from hypercholesterolemic rabbits. Effects of these reactive oxygens and that of peroxynitrite, likely to result from simultaneous production of nitric oxide and superoxide, were tested in vitro using metalloproteinases secreted by cultured human vascular smooth muscle cells. Enzymes in culture media or affinity-purified (pro-MMP-2 and MMP-9) were examined by SDS-PAGE zymography, Western blotting, and enzymatic assays. Under the conditions used, incubation with xanthine/xanthine oxidase increased the amount of active gelatinases, while nitric oxide donors had no noticeable effect. Incubation with peroxynitrite resulted in nitration of MMP-2 and endowed it with collagenolytic activity. Hydrogen peroxide treatment showed a catalase-reversible biphasic effect (gelatinase activation at concentrations of 4 microM, inhibition at > or = 10-50 microM). Thus, reactive oxygen species can modulate matrix degradation in areas of high oxidant stress and could therefore contribute to instability of atherosclerotic plaques.  相似文献   
63.
The influence of octreotide and somatostatin on liver metabolic activity were studied in 16 patients with cirrhosis that was positive for hepatitis B surface antigen (HBsAg). In patients receiving a 50 micrograms bolus and a 50 micrograms/hr infusion of octreotide, the hepatic blood flow, hepatic clearance, and the maximum velocity/metabolic elimination rate constant (Vmax/km) were significantly reduced after octreotide infusion compared with basal values. Similarly, the hepatic blood flow, hepatic clearance, and Vmax/km were significantly decreased in patients receiving a 250 micrograms bolus and a 250 micrograms/hr infusion of somatostatin. The extraction ratio and the systemic hemodynamic values, including cardiac index, heart rate, mean arterial pressure, and systemic vascular resistance, showed no significant changes in patients receiving either octreotide or somatostatin. These findings suggest that, as with somatostatin, octreotide reduced hepatic blood flow and impaired liver metabolic activity in patients with HBsAg-positive cirrhosis. These effects may have important clinical implications in the management of bleeding esophageal varices in patients with cirrhosis.  相似文献   
64.
目的 探讨消化性溃疡合并出血的治疗和护理措施.方法 对80例消化道溃疡合并出血者,采用积极的内科治疗及适当的护理措施.结果 治愈78例,占97.3%,2例转外手术治疗,占2.7% .结论 积极的内科治疗加适当的护理可有效治疗消化道出血.  相似文献   
65.
School-age children have learning needs unique to their psychosocial and cognitive developmental stage. Teaching that requires the learner to master abstract concepts is particularly challenging. This article describes how the idea for an interactive doll/model evolved among a group of health care professionals at a day camp for children with asthma. How this group of educators designed, developed, and field-tested the model in clinic and classroom environments are presented and discussed. Strategies related to a class on key concepts of asthma education illustrate the various ways the model can be used to facilitate learning. Field testing has shown that this teaching aid enhances knowledge retention and has a high degree of learner satisfaction.  相似文献   
66.

Background:

Renal sympathetic nerves are involved in the reflective activation of the sympathetic nervous system in circulatory control. Catheter-based renal denervation (RDN) ameliorated treatment-resistant hypertension safely, but 10%–20% of treated patients are nonresponders to radiofrequency denervation. The purpose of this study was to investigate the safety and efficiency of cryoablation for sympathetic denervation in a swine model and to explore a new way of RDN.

Methods:

Seven swines randomly assigned to two groups: Renal cryoablation (CR) group and control group. The control group underwent renal angiogram only. The CR group underwent renal angiogram plus bilateral renal cryoablation. Renal angiograms via femoral were performed before denervation, after denervation and prior to the sacrifice to access the diameter of renal arterial and the pressure of aorta abdominalis. Euthanasia of the swine was performed on 28-day to access norepinephrine (NE) changes of the renal cortex and the changes of renal nerves.

Results:

Cryoablation did not induce severe complications at any time point. There was no significant change in diameter of renal artery. CR reduced systolic blood pressure (BP) from 145.50 ± 9.95 mmHg at baseline to 119.00 ± 14.09 mmHg. There was a slight but insignificant decrease in diastolic BP. The main nerve changes at 28-day consisted of necrosis with perineurial fibrosis at the site of CR exposure in conjunction with the nerve vacuolation. Compared with the control group, renal tissue NE of CR group decreased by 89.85%.

Conclusions:

Percutaneous catheter-based cryoablation of the renal artery is safe. CR could effectively reduce NE storing in the renal cortex, and the efficiency could be maintained 28-day at least.  相似文献   
67.
The present study was to examine the distribution of lymphatic vessels in the penis of normal adult males, which could provide an anatomical basis for improvement of incisions in penile lengthening surgery, and may also help to prevent postoperative refractory edema. Thirteen normal adult male volunteers were recruited for this study. Contrast agent was injected subcutaneously in the foreskin of the penis, and after two minutes magnetic resonance lymphangiography (MRL) was performed. The acquired magnetic resonance images were analyzed to determine the changes in the number and diameter of lymphatic vessels in different parts of the penis. Maximum intensity projections (MIP) and materializes interactive medical image control system (MIMICS) were applied to analyze the overall distribution of lymphatic vessels in the penis. Magnetic resonance imaging (MRI) showed that the lymphatic vessels were in conspicuous contrast with surrounding tissues and could be clearly identified. Penile lymphatic vessels were clearly visible in the root of the penis. At the junction of the penis and the abdominal wall, all lymphatic vessels were found to be concentrated in the dorsal part of the penis. MIP two‐dimensional reconstruction showed that the overall distribution of relatively large lymphatic vessels in the dorsal and ventral parts of the penis could be seen clearly on bilateral 45° position, but not inside the abdominal wall because some of lymphatic vessels were overlapped by other tissues in the abdomen. MIMICS three‐dimensional reconstruction was able to reveal the overall spatial distribution of lymphatic vessels in the penis from any angle. The reconstruction results showed that there were 1–2 main lymphatic vessels on the root of dorsal penis, which coursed along the cavernous to the first physiological curvature of the penis. Lymphatic vessels merged on both sides of the ventral penis. At the root of the penis, lymphatic vessels gradually coursed to the dorsal surface of the penis and folded at the abdominal wall to the outside, and finally merged into the inguinal lymph nodes. The changes in distribution, number and diameter of the lymphatic vessels in the penis were observed by MRI. MIP and MIMICS reconstructions directly revealed the anatomical features of penile lymphatic vessels such as spatial distribution, overall alignment, and the relations to adjacent structures, drainage and reflux. The study will provide the anatomical basis for penile surgery, penile lymphatic reflux disorders caused by trauma or lymphatic vessels obstruction, and lymph node metastasis in penile cancer. Anat Rec, 298:1465–1471, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
68.
Renal cell carcinoma has become the most common subtype of kidney cancer, and has the highest propensity to manifest as metastatic disease. Because of lack of knowledge in events that correlated with tumor cell migration and invasion, few therapeutic options are available. Therefore, in current study, we explore the anti-tumoral effect of a potential chemopreventive natural product, quercetin, combined with anti-sense oligo gene therapy (inhibiting Snail gene). We found that either one of them had the remarkable effects in suppressing cell proliferation and migration, inducing cell cycle arrest and apoptosis in a ccRCC cell line, Caki-2 cells. The combination of both means provides even strong suppressive effects toward these ccRCC cells. Our study, for the first time, provides the possibility of using a novel treatment for renal cancer, by combining natural product and gene therapy.  相似文献   
69.
Metastases to the breast from extramammary malignancies are extremely rare. Ruling out the diagnosis of primary breast tumor is important in order to decide on clinical management and predict prognosis. We report a case of metastasis to the breast from a pulmonary adenocarcinoma, with extensive micropapillary component, diagnosed concomitantly with the primary tumor. A 52 year-old female patient presented with mammary gland tingling and dyspnea accompanied with fatigued of 4 months duration and a nodular shadows in the front of the upper lobe was found on a chest computed tomography (CT) scan. The original clinical diagnosis was right breast cancer with lung and bone metastasis, or breast and lung double primary cancers. In addition,on physical examination a poorly defined mass was noted in the upper outer quadrant of the right breast. The patient underwent thoracocentesis and breast biopsy. By imageology, cytology, histology and immunohistochemistry, we diagnosed primary lung cancer with metastases to the right breast and bone. The metastatic anatomic sites demonstrated histologically extensive micropapillary component, which is recently recognized as an important prognostic factor. The patient was administered 4 cycles of cisplatin and docetaxel, although no clinical response was seen, the patient is still alive 9 months after diagnosis. The result of immunohistochemistry is a useful supplement in differential diagnosis.  相似文献   
70.
Membrane-type 1 matrix metalloproteinase (MT1-MMP, also known as MMP14), the best characterized membrane-anchored MMP, is an important matrix-degrading proteinase that could digest a broad spectrum of extracellular matrix proteins and accelerate angiogenesis. We have previously reported that some MMPs involved in the angiogenesis and the pannus formation within the joint, leading to the erosion of articular cartilage and bone in the pathological process of rheumatoid arthritis (RA). In the present study, we used immunohistochemistry assay and con-focal scanning technique to study the detailed immunolocalization of MT1-MMP in human RA synovium tissues as well as the infiltrating immune cell subsets. Our results showed that the positive MT1-MMP immunostaining could be found in synoviocytes, vascular endothelial cells, infiltrating macrophages and monocytes in RA synovium tissues, while weak or negative immunostaining could be found in infiltrating T cells, B cells and NK cells, respectively. Moreover, the Ki-67+ highly proliferating synoviocytes also showed higher MT1-MMP expression in RA synoviocytes. Thus, the aberrant expression of MT1-MMP in RA synoviocytes as well as infiltrating immune cells may contribute to the proliferation of the synoviocytes, and the angiogenesis and the pannus formation in RA pathological progression.  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