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   62461篇
  免费   5364篇
  国内免费   2433篇
耳鼻咽喉   704篇
儿科学   747篇
妇产科学   1222篇
基础医学   9377篇
口腔科学   1529篇
临床医学   5727篇
内科学   11535篇
皮肤病学   1120篇
神经病学   4332篇
特种医学   2053篇
外国民族医学   16篇
外科学   8258篇
综合类   5664篇
现状与发展   5篇
一般理论   6篇
预防医学   3696篇
眼科学   1832篇
药学   5810篇
  7篇
中国医学   1344篇
肿瘤学   5274篇
  2023年   348篇
  2022年   744篇
  2021年   1082篇
  2020年   734篇
  2019年   980篇
  2018年   1519篇
  2017年   1186篇
  2016年   1191篇
  2015年   1439篇
  2014年   1857篇
  2013年   2089篇
  2012年   2944篇
  2011年   2989篇
  2010年   1852篇
  2009年   1657篇
  2008年   2458篇
  2007年   2465篇
  2006年   2323篇
  2005年   2032篇
  2004年   1692篇
  2003年   1626篇
  2002年   1514篇
  2001年   4825篇
  2000年   4800篇
  1999年   4159篇
  1998年   1532篇
  1997年   1136篇
  1996年   746篇
  1995年   603篇
  1994年   543篇
  1993年   466篇
  1992年   1995篇
  1991年   1732篇
  1990年   1590篇
  1989年   1526篇
  1988年   1328篇
  1987年   1221篇
  1986年   1094篇
  1985年   920篇
  1984年   598篇
  1983年   475篇
  1982年   252篇
  1981年   185篇
  1980年   146篇
  1979年   285篇
  1978年   78篇
  1976年   71篇
  1974年   81篇
  1973年   104篇
  1972年   76篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
991.
鼻咽癌茎突后间隙侵犯的临床意义探讨   总被引:7,自引:0,他引:7  
目的 探讨鼻咽癌茎突后间隙侵犯的临床意义。方法 1992年12月~1993年12月198Ⅰ-Ⅳa期鼻咽癌住院初治患者接受受根治性放射治疗。按茎突后间隙有无侵犯分为茎后侵犯组和茎后无侵犯组。应用Kaplan-Meier,Log-Rank及卡方检验等方法对两组患者5年生存率、局部控制率和无远处转移生存率进行分析和评价。结果两组患者口咽侵犯率分别为72.1%和16.8%(P〈0.001),后组颅神经侵犯  相似文献   
992.
The purpose of this study was to define the treatment of choice (partial laryngectomy vs radiotherapy) in the early stage of supraglottic squamous cell cancer (ESSC). One hundred and fifteen patients with ESSC were treated with either partial laryngectomy (25 patients) or with radiotherapy(90 patients) between January 1984 and December 1996. All patients had a follow-up of over ¶29 months. Radiotherapy (RT) had a local control rate of 79%, which increased to 90% with salvage surgery, and a high larynx preservation rate (83%). Partial laryngectomy (PL) offered a better initial local control rate of 84%, which increased to 88% with salvage surgery, and functional results were also good (80%). No statistically significant differences were found between RT and PL. RT was less costly, showed better suitability for treatment, produced moderate morbidity and sequelae, and local recurrence was easier to rescue. However, it is a once-only application technique. PL showed higher immediate postoperative morbidity, higher cost and lower suitability for treatment but had fewer sequelae, offered the best initial local control and is multi-applicable. No clear oncological arguments were found in our series to define whether PL or RT is the treatment of choice for ESSC. Both are effective therapies. Secondary factors such as suitability for treatment, morbidity, cost and applicability should be individually evaluated when choosing the type of treatment. As the laser endoscopic approach decreases morbidity and costs and makes the condition more suitable for treatment, it could be the treatment of choice for ESSC, in cases where local tumoral extent and larynx exposure allow radical excision.  相似文献   
993.
H Wu  S Qu  Q Huang  J Deng  Y Zhang  J Li 《华西医科大学学报》2000,31(2):169-70, 179
This study was aimed at the angiotensin converting enzyme (ACE) gene insertion/deletion(I/D) polymorphism distribution in Chinese and its relationship with serum ACE activity(SACE). SACE activity and ACE gene polymorphism in 90 healthy persons in Chengdu region were investigated using a spectrophotometric assay and the PCR technique, respectively. The results showed that, in the Hans, DD genotype of ACE gene was 18%, DI genotype 44%, and II genotype 38%. Allele frequencies were 0.40 for the D allele and 0.60 for the I allele. There were significant relationships between ACE I/D polymorphism and SACE activity. The results suggest that ACE genotype distribution be different between races, that II genotype and I allele be more frequent in Chinese, and that SACE activity be under the influence of a genetic polymorphism of ACE in Chinese.  相似文献   
994.
S Jiang  S Yuan  Y Wang  X Chen  Y Song  Y Yang  B Mao 《华西医科大学学报》2000,31(2):191-2, 232
In this study, the chemosensitivity of 36 cases' fresh neuroglioma specimens was examined in vitro with MTT assay. The separation method for single tumor cell, the number of planting of cells, and the dosage and acting time of drugs, which have effects on the results of MTT assay, were studied systematically. On the basis of this experiment, we established a screening method for the chemosensitivity of neuroglioma; it is accurate, rapid, and simple. At the same time, the results showed that neuroglioma was more sensitive to the chemotherapeutic drugs Vm26, DDP and MMC, and the sensitivity varied with not only the drugs but also the individuals.  相似文献   
995.
Neurofibromatosis is a dominantly inheriteddefect of the ectoderm,characterized by cafe au laitspots since the childhood and multiple tumorsderived from elements of peripheral and cranialnerves.Hernia-like tumors of various sizes can oftenbe felt under the skin and serve as a valuablecharacteristic in making diagnosis.However,theycan also affect brain,vegetative nerve system or othertissues and lead to bony abnormalities,mentaldisturbances and sometimes,endocrine abnormalities,  相似文献   
996.
目的 通过使用不同成像序列及接收线圈,寻找最佳非增强门脉磁共振成像技术。方法 对20例上腹部受检者行门静脉成像。以轴位为定位像,行冠状位扫描。其中10例GRASS、GRASS+EATSAT、SPGR、SPGR+FATSAT4种序列扫描;10例以体线圈、GPF线圈及胸腰椎线圈和GRASS扫描。所得图像均进行MIP重建,并对MIP重建图像门静脉显示效果进行对比评价。结果 SPGR,GRASS信噪比、对  相似文献   
997.
H Wu  S Qu  Y Zhang  J Deng  J Li  J Zhou 《华西医科大学学报》2000,31(3):373-375
This investigation was made with reference to the changes of serum angiotensin converting enzyme (SACE) activity in type 2 diabetes and its vascular complications. SACE activity was studied in 127 type 2 diabetic patients and 90 healthy persons by using a spectrophotometric assay. The results showed SACE activity was obviously higher in diabetic patients (459.51 +/- 175.85 U) than in healthy persons (321.14 +/- 121.27 U); SACE activity was significantly higher in type 2 diabetic patients with diabetic nephropathy (548.27 +/- 166.60 U) than in patients without diabetic nephropathy (383.2 +/- 139.00 U), but there was no difference between patients with microalbuminuria and macroalbuminuria; no statistical difference was detected in SACE activity between diabetic patients with diabetic retinopathy (465.64 +/- 178.93 U) and without retinopathy (449.07 +/- 170.04 U); SACE activity was not associated with the course of diabetes, blood pressure, blood lipid and blood glucose. These data suggest that raised SACE activity might only play a role in the initiation of type 2 diabetes and diabetic nephropathy, but not relate to the progress of diabetic nephropathy, the onset of diabetic retinopathy and hypertension.  相似文献   
998.
Luminol-hemin system was used for chemiluminescent flow-injection analysis with immobilized glucoxidase(GOD) column to determine blood glucose. The method is fast, simple and sensitive. Blood samples were diluted to 1:1000 and pumped into the flow-injection analyzer for direct detection. The sampling frequency was 30 samples/h, with a detection limit of 7.2 x 10(-9) mol/L(1.30 micrograms/L). A column packed with 36 milligrams of CPG could be used nearly 200 times. The determination results of glucose in serum by this method were in good agreement with those obtained by the routine GOD spectrophotometric method (correlation coefficient r = 0.90, P > 0.05). Recoveries of this method were 94.0%-107.2%.  相似文献   
999.
The changes of type I collagen in the lung tissues of rats with hypoxic pulmonary hypertension (HPH) and its relationship to the mean pulmonary arterial pressure (mPAP) were investigated. The blood dynamic indexes of pulmonary circulation were measured by using Swan-Ganz. The distribution of type I collagen in pulmonary arteries, bronchi and plumonary interstitial was observed by using streptavidin peroxidase method (SP). The morphologic changes of small pulmonary arteries and the level of type I collagen were determined by image pattern analysis technique and gray scale scanning, respectively. The results showed, compared with the controls, mPAP of the hypoxic rats elevated (from 2.12 +/- 0.25 to 3.95 +/- 0.43 kPa, P < 0.01), their small pulmonary arteries, walls thickened (MT% from 16.35 +/- 2.64 to 35.83 +/- 3.55, MA% from 26.83 +/- 3.40 to 59.68 +/- 4.90, P < 0.01) and lumen narrowed. The distribution of type I collagen was mainly in the external layer of pulmonary arterial walls; the positive degrees of gray scale scanning increased and had a positive linear relationship to the mPAP and MT%. These findings suggest that the increase of type I collagen contents in pulmonary arteries is closely related to the development of HPH.  相似文献   
1000.
X Liu  Z Zhang  L Yang  D Chen  Y Wang 《华西医科大学学报》2000,31(2):133-5, 142
In order to investigate the inhibition of the activation and collagen production of cultured rat hepatic stellate cells (HSC) by antisense oligonucleotides (ASON) against TGF beta 1 after cationic liposome (lipofectin) delivery, the authors synthesized a 20-mer phosphorothioate antisense oligonucleotide of TGF beta 1 mRNA, and its sense of missense oligonucleotides, and then treated the HSC with cationic liposome/oligonucleotide complexes respectively. The cellular uptake of 32P-labelled oligonucleotides was determined by liquid scintillation counting, and HSC activation was assessed by the expression of alpha-smooth muscle actin(alpha-SMA). The cellular uptake of lipofectin/32P-ASON complex was approximately five-fold higher than that of 32P-ASON alone. Cationic liposome (lipofectin) delivery significantly increased the inhibition of HSCs activation by ASON, while compared with the use of naked TGF beta 1 ASON at the same concentration (at a final concentration of 1 mumol/L, P < 0.05). However, these effects were not observed in lipofectin alone, liposome/sense or missense oligos complexes at the same concentration. The oligonucleotide or lipofectin/oligos complexes had no cytotoxicity to rat HSCs in culture. These findings suggest that cationic liposome is an effective vehicle to improve the delivery of ASON to rat HSCs in culture, and the cationic liposome/TGF beta 1 ASON complex may be useful for the treatment of hepatic fibrosis.  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