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   39770篇
  免费   2450篇
  国内免费   829篇
耳鼻咽喉   144篇
儿科学   788篇
妇产科学   467篇
基础医学   4056篇
口腔科学   357篇
临床医学   6356篇
内科学   6961篇
皮肤病学   228篇
神经病学   1917篇
特种医学   1010篇
外国民族医学   2篇
外科学   3305篇
综合类   6862篇
现状与发展   4篇
预防医学   3359篇
眼科学   159篇
药学   4220篇
  18篇
中国医学   2232篇
肿瘤学   604篇
  2023年   440篇
  2022年   749篇
  2021年   1288篇
  2020年   1251篇
  2019年   1021篇
  2018年   1043篇
  2017年   1104篇
  2016年   1202篇
  2015年   1228篇
  2014年   2473篇
  2013年   2804篇
  2012年   2370篇
  2011年   2437篇
  2010年   1938篇
  2009年   1868篇
  2008年   1743篇
  2007年   1747篇
  2006年   1632篇
  2005年   1416篇
  2004年   1209篇
  2003年   1126篇
  2002年   962篇
  2001年   900篇
  2000年   876篇
  1999年   722篇
  1998年   641篇
  1997年   611篇
  1996年   524篇
  1995年   534篇
  1994年   489篇
  1993年   424篇
  1992年   376篇
  1991年   349篇
  1990年   322篇
  1989年   267篇
  1988年   304篇
  1987年   271篇
  1986年   203篇
  1985年   277篇
  1984年   303篇
  1983年   190篇
  1982年   228篇
  1981年   194篇
  1980年   174篇
  1979年   125篇
  1978年   112篇
  1977年   102篇
  1976年   78篇
  1975年   63篇
  1973年   81篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
51.
血栓的形成及中药抗栓溶栓概况   总被引:11,自引:0,他引:11  
血栓形成是由于正常的凝血机制的扰乱而促使某些血细胞和蛋白质被激活相互作用而最终导致血小板-纤维蛋白血栓的形成.AT-Ⅲ、PC、TM是体内重要的抗凝物质.白细胞与血小板的相互作用、PGI2/TXA2值以及许多疾病状态是影响血栓形成的诸因素.许多中药具有抗血小板聚集、抗血栓形成的作用,包括生物碱类,如小檗碱、北豆根碱和钩藤碱;中药蒲黄、花椒、沙棘、大蒜的提取物;一些中药复方等.  相似文献   
52.
Purpose: To assess the accuracy of intraarterial measurement of transstenotic pressure gradients for the detection of hemodynamically suboptimal iliac angioplasty. Methods: In 14 patients, referred for diagnostic angiography, mean pressure gradients in the aorta and iliac artery were obtained twice, using a double-sensor pressure catheter. Additional iliac measurements were performed during pharmacologically induced flow augmentation. Repeatability was assessed by calculation of the mean difference plus standard deviation (MD ± SD) and repeatability coefficient (2 × SD). These results were extrapolated to 137 iliac angioplasty procedures with secondary stenting where there was a residual pressure gradient > 10 mmHg. Results: MD ± SD for repeated measurements at rest and during flow augmentation were 0 ± 2 mmHg and 1 ± 3 mmHg, respectively. Repeatability coefficients were 3 and 6 mmHg. Mean pressure gradients after hemodynamically insufficient angioplasty were 8 ± 7 mmHg at rest and 17 ± 5 mmHg following vasodilatation. Inaccurate pressure recordings may have led to inappropriate stent placement in less than 2.5%, and inappropriate denial of stent placement in less than 5% of the lesions. Conclusion: Variability of intraarterial pressure measurements has little consequence in the detection of hemodynamically significant stenosis after angioplasty. Received: 0/00/00/Accepted: 0/00/00  相似文献   
53.
Oxygen-sensitive F-19 magnetic resonance imaging of perfluorocarbon compounds requires that fluorocarbon T1 changes correlate with the local Po2 and not with the composition of the surrounding aqueous phase. The influence of various bioconstituents and paramagnetic ions within the aqueous phase on the F-19 fluorocarbon phase T1 for PFC emulsions was evaluated at 0.14 and 0.66 T. T1 was measured for FC-43, perflubron, and a fluorinated surfactant. Controlled variables introduced in the aqueous phase included annex solution constituents, blood, pH changes, and Gd-DTPA. For a constant Po2, the F-19 T1s were independent of the emulsion constituents, blood concentration, and pH. For FC-43 and perflubron, F-19 T1 was independent of the Gd-DTPA concentration, while the aqueous phase T1 decreased by more than an order of magnitude. XMO-10 (smallest emulsion particle size) showed a slight decrease in F-19 T1 with increasing Gd-DTPA concentration at 0.66 T.  相似文献   
54.
棕榈油对成人血脂和血小板功能的影响   总被引:3,自引:0,他引:3  
张坚  王春荣 《营养学报》1997,19(2):186-190
报道了棕榈油(PA),花生油(PE)对血清总胆固醇水平(TC)在5.5~7.0mmol/L的受试者血脂和血小板功能的影响。51名受试者(男31人,女20人,年龄30~66岁之间)分为两组,一组男15人,女11人,称PE组;另一组男16人女9人,称PA组,预备期3周,膳食以当地日常食用的花生油烹调,实验期6周。PA组受试者食用以棕榈油烹调的实验膳;PE组受试者仍食花生油烹调的膳食。脂肪约占膳食能量的30%,其中60%~65%来自实验油。实验结果表明:与起始值相比,6周末PA组受试者血清TC,低密度脂蛋白胆固醇(LDL-C)和总胆固醇与高密度脂蛋白胆固醇比值(TC/HDL-C)显著下降,血浆血栓素B2(TXB2)/6-酮前列环素F1α、(6-keto-PGF1α)比值显著下降,全血血小板聚集率未见显著变化。PE组受试者的血脂、血浆TXB2、6-keto-PGF1α及全血血小板聚集率等指标均未出现显著变化。提示,棕榈油作为我国居民家庭烹调用油并不会增加发生心血管疾病的危险。  相似文献   
55.
卵巢恶性肿瘤与血小板增多关系分析   总被引:1,自引:0,他引:1  
目的探讨卵巢恶性肿瘤伴发血小板增多的临床规律。方法回顾分析98例卵巢恶性肿瘤患者的临床资料,26例合并血小板增多。结果血小板增多占26.5%,其中晚期(Ⅲ+Ⅳ期)占88.46%,晚期患者血小板偏高明显增多,且肿瘤切除后血小板下降。结论卵巢恶性肿瘤伴发血小板增多晚期患者多见,预后差,血小板增多可作为判断卵巢肿瘤恶性程度及术后随访的指标。  相似文献   
56.
57.
58.
This study was conducted to investigate the hypocholesterolemic effect of simvastatin (30 mg/kg BW) and antioxidant effect of coenzyme Q10 (CoQ10, 15 mg/kg BW) or green tea (5%) on erythrocyte Na leak, platelet aggregation and TBARS production in hypercholesterolemic rats treated with statin. Food efficiency ratio (FER, ADG/ADFI) was decreased in statin group and increased in green tea group, and the difference between these two groups was significant (p<0.05). Plasma total cholesterol was somewhat increased in all groups with statin compared with control. Plasma triglyceride was decreased in statin group and increased in groups of CoQ10 and green tea, and the difference between groups of statin and green tea was significant (p<0.05). Liver total cholesterol was not different between the control and statin group, but was significantly decreased in the group with green tea compared with other groups (p<0.05). Liver triglyceride was decreased in groups of statin and green tea compared with the control, and the difference between groups of the control and green tea was significant (p<0.05). Platelet aggregation of both the initial slope and the maximum was not significantly different, but the group with green tea tended to be higher in initial slope and lower in the maximum. Intracellular Na of group with green tea was significantly higher than the control or statin group (p<0.05). Na leak in intact cells was significantly decreased in the statin group compared with the control (p<0.05). Na leak in AAPH treated cells was also significantly reduced in the statin group compared with groups of the control and CoQ10 (p<0.05). TBARS production in platelet rich plasma was significantly decreased in the groups with CoQ10 and green tea compared with the control and statin groups (p<0.05). TBARS of liver was significantly decreased in the group with green tea compared with the statin group (p<0.05). In the present study, even a high dose of statin did not show a cholesterol lowering effect, therefore depletion of CoQ10 following statin treatment in rats is not clear. More clinical studies are needed for therapeutic use of CoQ10 as an antioxidant in prevention of degenerative diseases independent of statin therapy.  相似文献   
59.
Platelet factor 4 ( PF4) is a negativehematopoietic factor.It can inhibit the prolifera-tion of endothelial cells and hematopoietic stem/progenitor cells,particularly megakaryoryocyticcells,reversibly[1] ,inhibit DNA synthesis,blockcell cycle progression during S phase and reducethe sensibility of normal hematopoietic stem/pro-genitor cells,but not some cancer or leukemia celllines,to cytotoxic drugs and ionizing radia-tion[2 - 3] ,and it also can cause a population in-crease of the stem cel…  相似文献   
60.
目的观察初诊T2DM短期胰岛素强化治疗的疗效。方法对40例初诊T2DM患者采用三餐前皮下注射短效胰岛素和睡前注射中效胰岛素2wk,并检测治疗2wk前后FPG、PPG、GHbA1C及血脂等值进行比较。结果两组治疗后FPG、PPG、GHbA1C及血脂各值均显著低于治疗前p〈0.05(x^2=4.940—11.544)。结论胰岛13细胞功能异常和(或)胰岛素抵抗是T2DM发病的基本环节,早期强化胰岛素治疗能获得血糖的有效控制,减少或延缓并发症的发生。  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