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   8223篇
  免费   706篇
  国内免费   635篇
耳鼻咽喉   85篇
儿科学   81篇
妇产科学   44篇
基础医学   881篇
口腔科学   120篇
临床医学   1142篇
内科学   1042篇
皮肤病学   55篇
神经病学   328篇
特种医学   328篇
外科学   772篇
综合类   1831篇
现状与发展   2篇
一般理论   2篇
预防医学   666篇
眼科学   219篇
药学   840篇
  5篇
中国医学   619篇
肿瘤学   502篇
  2024年   12篇
  2023年   88篇
  2022年   245篇
  2021年   370篇
  2020年   300篇
  2019年   197篇
  2018年   238篇
  2017年   266篇
  2016年   212篇
  2015年   352篇
  2014年   469篇
  2013年   499篇
  2012年   766篇
  2011年   882篇
  2010年   623篇
  2009年   500篇
  2008年   609篇
  2007年   502篇
  2006年   477篇
  2005年   455篇
  2004年   272篇
  2003年   231篇
  2002年   156篇
  2001年   126篇
  2000年   132篇
  1999年   113篇
  1998年   62篇
  1997年   34篇
  1996年   54篇
  1995年   47篇
  1994年   36篇
  1993年   29篇
  1992年   22篇
  1991年   27篇
  1990年   21篇
  1989年   26篇
  1988年   15篇
  1987年   13篇
  1986年   20篇
  1985年   14篇
  1984年   7篇
  1983年   7篇
  1982年   4篇
  1980年   4篇
  1979年   3篇
  1978年   4篇
  1975年   4篇
  1974年   3篇
  1971年   2篇
  1967年   2篇
排序方式: 共有9564条查询结果,搜索用时 15 毫秒
1.
This study investigated the hypocholesterolaemic effects of bitter melon aqueous extracts (BMAE) in vitro, the inhibitory effects of BMAE on pancreatic cholesterol esterase (CEase) and incorporation of cholesterol into micelles were investigated. BMAE decreased the in vitro micellar solubility of cholesterol in a dose-dependent manner. The conformation of CEase was investigated by means of circular dichroism (CD) and fluorescence. The result revealed the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. The incorporation of cholesterol into micelles was inhibited by BMAE. A complex was observed by transmission electron microscopy (TEM), which indicated interaction between cholesterol and BMAE. The result revealed that BMAE can play a role in decreased intestinal cholesterol absorption via inhibition of CEase, and of micelle formation.  相似文献   
2.
目的分析2014-2018年黄山市淋病的流行特征,为全市的淋病防控工作提供科学依据。方法通过中国疾病预防控制信息系统收集黄山市2014—2018年的淋病数据、人口数据,进行统计分析。结果2014—2018年黄山市累计报告淋病病例761例,年均发病率为11.09/10万,年均增长率为29.14%,发病率呈逐年上升趋势(χ^2趋势=112.29,P<0.05)。淋病的人群分布中,男女报告病例数之比为13.63:1,男女发病率有统计学差异(χ^2=113.18,P<0.05);15~49岁年龄组病例数最多,占85.94%,职业以农民最多,占44.81%;以屯溪区、歙县报告病例数较多,分别占37.45%、23.26%。结论2014—2018年黄山市淋病发病率呈上升趋势,淋病防控形势严峻,需进一步完善各项防控措施。  相似文献   
3.
股骨重建钉在股骨粗隆下骨折手术中的应用   总被引:1,自引:1,他引:0  
[目的]探讨股骨重建钉(RIN)治疗股骨粗隆下骨折(SFF)的手术方法及临床疗效。[方法]1998年6月-2005年5月,采用RIN技术对4JD例SFF患者进行固定,其中男27例,女13例;年龄22..75岁。平均43.5岁。依据Seinsheimer分类:Ⅱ型5例,Ⅲ型13例,Ⅳ型21例,Ⅴ型1例。高能量损伤33例,低能量损伤7例。开放性骨折3例。[结果]4JD例随访8个月-2a6个月,平均1a8个月。X线片观察骨折愈合时间4.2月(3.2-6.5月)。按照韩一生评分标准,优26例,良12例,可2例,优良率95%。无感染、内固定失效、畸形愈合及股骨头缺血性坏死等并发症。[结论]RIN技术是治疗SFF的一种有效方法,具有固定可靠、并发症少、骨折愈合率高等优点。精细的手术操作是手术成功的关键。  相似文献   
4.
白纹伊蚊在竹林里孳生的阳性比为75.4%;而在竹林包围的居民区阳性比为15.3%。白纹伊蚊在居民区孳生密度布雷图指数为19.4,容器指数为6.2%。居民区孳生蚊虫的主要场所是泡菜坛,泡菜坛主要孳生蚊种是骚扰阿蚊,阳性比为73.7%,其次是淡色库蚊为20.2%,贪食库蚊为14.0%,白纹伊蚊最低,为9.1%。  相似文献   
5.
从抗氧化角度探讨了四君子汤抗氧化的作用机制。结果表明,显著提高缺彬再灌损伤大鼠脑、血清中SOD活力,降低MDA含量;在体外实验中,明显抑制脑过氧化脂质的生成,具有清除羟自由基、超氧阴离子的作用。结论是四君子汤具有一定的抗氧化作用,健脾化痰抗氧化理论有一定的实验依据。  相似文献   
6.
Our objective was to develop and evaluate 3 semiautomatic computer-aided diagnostic (CAD) schemes for distinguishing between benign and malignant pulmonary nodules by use of features extracted from CT, 18F-FDG PET, and both CT and 18F-FDG PET. METHODS: We retrospectively collected 92 consecutive cases of pulmonary nodules (<3 cm) in patients who underwent both thoracic CT and whole-body PET/CT. Forty-two of the nodules were malignant and 50 benign, as confirmed by pathologic examination and clinical follow-up. The interval between CT and PET was less than 1 mo. Four clinical parameters, including patient age, sex, smoking status, and history of previous malignancy, were used for the CAD schemes. Sixteen CT features based on size, shape, margin, and internal structure of nodules were independently rated subjectively by 2 chest radiologists. Four PET features were viewed on a PET/CT workstation. CAD schemes based on clinical parameters together with CT features, PET features, and both CT and PET features were then used to differentiate benign from malignant nodules. Finally, the output from the CAD schemes was evaluated by use of receiver-operating-characteristic analysis. RESULTS: When we used clinical parameters and CT features as input units (CAD scheme 1), the area under the receiver-operating-characteristic curve (A(z) value) of the CAD scheme was 0.83. When we used clinical parameters and PET features as input units (CAD scheme 2), the A(z) value for the computer output was 0.91. However, when we used all data as input units (CAD scheme 3), the A(z) value for the computer output was 0.95. The performance of CAD scheme 3 was better than that of CAD scheme 1 or 2. A statistically significant difference existed between the A(z) values of CAD schemes 3 and 2 (P = 0.037) and between those of CAD schemes 3 and 1 (P = 0.015). CONCLUSION: Our CAD scheme based on both PET and CT was better able to differentiate benign from malignant pulmonary nodules than were the CAD schemes based on PET alone and CT alone.  相似文献   
7.
背景:与小肠黏膜下层等材料相比,脱细胞血管具有天然管状结构,与输尿管形态结构相近,替代输尿管时仅需端端吻合即可,手术操作简单,血管外壁光滑,获取及制备方法简便等优点。 目的:拟应用同种颈动脉血管无细胞基质体外构建输尿管。 设计、时间及地点:观察性实验,于2006-09/2008-06在上海交通大学医学院附属新华医院动物实验中心完成。 材料:长风杂交白猪由上海松联实验动物公司提供。上海交通大学医学院实验动物中心提供的健康成年大鼠8只,用于血管无细胞基质的动物毒性实验。 方法:剥去猪颈动脉血管外膜,PBS冲洗若干遍,然后将血管置于pH 7.1 的PBS中4 ℃下振荡清洗,0.5%十二烷基硫酸钠振荡24 h,后使用双蒸水4 ℃下反复振荡洗涤1周,每日换双蒸水2次。对于解剖过程中肌肉残留相对稍多的血管,在双蒸水洗涤前以混合消化液37 ℃下振荡消化约2 h,再行双蒸水洗涤。制备的无细胞基质置于青、链霉素溶液中,4 ℃保存,完成脱细胞支架制备。 主要观察指标:光镜及电镜观察脱细胞后管壁无细胞基质片的主要成分。将同种异体来源内皮祖细胞培养增殖后植入血管无细胞基质,观察细胞生长情况,并进行血管无细胞基质动物毒性实验。拉力实验了解血管无细胞基质材料的收缩性能。 结果:颈动脉血管无细胞基质中已无细胞成分,无细胞基质主要由胶原成分组成。扫描电镜未见该材料表面存在细胞及细胞碎片,同时发现该无细胞基质存在孔隙样结构。体外同种异体来源的内皮祖细胞培养增殖后植入血管无细胞基质,细胞黏附于无细胞基质。血管无细胞基质按毒性分级属于无毒级。拉力实验说明该无细胞基质具有一定的韧性和牵张性。 结论:采用胰酶和十二烷基硫酸钠制备的颈动脉血管无细胞基质材料无细胞残留,具有一定的韧性和牵张性,种植于其中的种子细胞具备一定的生长能力。  相似文献   
8.
Changes in T .lymphocyte subsets after severe traumatic brain inJury   总被引:2,自引:0,他引:2  
BACKGROUND: Besides local changes of cranial parenchymal cells, hemorrhage, etc., severe traumatic brain injuries also cause the changes of total body fluid and various functions, and the changes of lymphocytes and T lymphocyte subsets should be paid more attention to. OBJECTIVE: To reveal the changing laws of T lymphocyte subsets after severe traumatic brain injury, and compare with mild to moderate brain injury. DESIGN: A comparative observation. SETTINGS: Department of Neurosurgery, Longgang District Buji People's Hospital of Shenzhen City; Central Laboratory of Shenzhen Hospital of Prevention and Cure for Chronic Disease. PARTICIPANTS: All the subjects were selected from the Department of Neurosurgery, Longgang District Buji People's Hospital of Shenzhen City from August 2002 to August 2005. Thirty patients with severe brain injury, whose Glasgow coma score (GCS) was ≤ 8 points, were taken as the experimental group, including 21 males and 9 females, aging 16 - 62 years. Meanwhile, 30 patients with mild traumatic brain injury were taken as the control group (GCS ranged 14- 15 points), including 18 males and 12 females, aging 15 -58 years. All the subjects were in admission at 6 hours after injury, without disease of major organs before injury Informed consents were obtained from all the patients or their relatives. METHODS: (1) The T lymphocytes and the subsets in peripheral blood were detected with immunofluorescent tricolor flow cytometry at l, 3, 7 and 14 days after injury in both groups. (2) The conditions of pulmonary infections were observed at 4 days after injury. The differences of measurement data were compared with the t test. MAIN OUTCOME MEASURES: Changes of T lymphocytes subsets at 1 - 14 days after severe and mild or moderate traumatic injury. RESULTS: Finally, 28 and 25 patients with mild to moderate traumatic brain injury, whereas 25 and 21 patients with severe traumatic brain injury were analyzed at 7 and 14 days respectively, and the missed ones died due to the development of disease. (1) Changes of T lymphocyte subsets: At 1 and 3 days after injury, CD3, CD4, CD8, CD4/CD8 began to decrease, whereas CD8 increased in the experimental group, which were very significantly different from those in the control group (t =2.77 - 3.26, P 〈 0.01), and began to recover at 7 days, which were significantly different from those in the control group (t = 2.06 - 2.24, P 〈 0.05), and generally recovered to the normal levels at 14 days (P 〉 0.05). (2) Conditions of pulmonary infections: At 4 days after injury, the rate of pulmonary infection was significantly different between the experimental group and control group [73% (22/30), 0, x2=37.29, P 〈 0.01]. CONCLUSION: Patients with severe traumatic brain injury suffer from damages of cellular immune function at early period (within 7 days), and they are easily to be accompanied by pulmonary infections.  相似文献   
9.
目的用MRI研究兔眼眶内植入羟基磷灰石(hydroxyapatite,HA)义眼台血管化过程,探讨义眼台血管化MRI表现和特点。方法12只新西兰白兔眼眶内植入直径12mmHA义眼台,于术后第2、3、4、5、6周对所有手术兔行双眼MR平扫及钆喷替酸葡甲胺(Gd-DTPA)增强扫描,计算义眼台强化区体积与义眼台体积比值(VE/VHA),对结果用单因素方差分析。并于第2、4周采用随机数字法抽取2只,第6周对剩余动物义眼台行组织病理学检查。结果术后第2、3、4、5、6周VE/VHA值分别为0.570±0.055;0.787±0.036;0.995±0.014;1.000±0.000;1.000±0.000。第2、3、4周VE/VHA值逐渐增加,均数间比较差异有统计学意义(F=233.094,P=0),第4、5、6周均数间比较差异无统计学意义(F=0.686,P=0.520)。术后2周病理显示义眼台周边有纤维血管生长,第4、6周整个义眼台完全血管化。结论MRI可直观、准确地评价义眼台血管化的程度和范围。  相似文献   
10.
[目的]探讨儿童先天性髋关节脱位的股骨和骨盆联合手术中洗涤式自体血液回收的应用方法与前景。[方法]2003年8月~2005年12月,17例先天性髋关节脱位股骨和骨盆联合手术中,使用Cell Saver 5血液回收系统行术中的血液回收。观察回输自体血液后的并发症发生情况,记录术中估计失血量、实际回收血量,以及回输血前后的Hb、Hct、P lt、PT、APTT、HR、BP、SPO2等的变化情况。[结果]17例患儿术中血液回收总量2 090 m l,平均每人(171±53)m l。其中4例出现一过性血红蛋白尿,其他无并发症。患者术前和术后24 h的Hb、Hct、HR比较差异有显著性意义(P<0.01);患者术前和术后24 h的P lt、PT、APTT、SPO2、BP比较差异无显著性意义(P>0.05)。[结论]儿童先天性髋关节脱位的股骨和骨盆联合手术中的血液回收是安全、有效的自体输血方式,明显节约异体血的用量,有效避免血液传播性疾病的发生。  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