全文获取类型
收费全文 | 69092篇 |
免费 | 6348篇 |
国内免费 | 3627篇 |
专业分类
耳鼻咽喉 | 493篇 |
儿科学 | 1049篇 |
妇产科学 | 1069篇 |
基础医学 | 9448篇 |
口腔科学 | 1607篇 |
临床医学 | 7422篇 |
内科学 | 11983篇 |
皮肤病学 | 932篇 |
神经病学 | 4924篇 |
特种医学 | 2433篇 |
外国民族医学 | 25篇 |
外科学 | 8314篇 |
综合类 | 8140篇 |
现状与发展 | 12篇 |
一般理论 | 10篇 |
预防医学 | 4112篇 |
眼科学 | 1639篇 |
药学 | 6826篇 |
15篇 | |
中国医学 | 2280篇 |
肿瘤学 | 6334篇 |
出版年
2024年 | 109篇 |
2023年 | 666篇 |
2022年 | 1536篇 |
2021年 | 2087篇 |
2020年 | 1618篇 |
2019年 | 1584篇 |
2018年 | 1925篇 |
2017年 | 1707篇 |
2016年 | 1648篇 |
2015年 | 2354篇 |
2014年 | 2834篇 |
2013年 | 2805篇 |
2012年 | 4225篇 |
2011年 | 4363篇 |
2010年 | 2688篇 |
2009年 | 2193篇 |
2008年 | 3263篇 |
2007年 | 3389篇 |
2006年 | 3099篇 |
2005年 | 3005篇 |
2004年 | 2264篇 |
2003年 | 2127篇 |
2002年 | 1776篇 |
2001年 | 3132篇 |
2000年 | 3168篇 |
1999年 | 2851篇 |
1998年 | 1300篇 |
1997年 | 1127篇 |
1996年 | 820篇 |
1995年 | 752篇 |
1994年 | 674篇 |
1993年 | 518篇 |
1992年 | 1296篇 |
1991年 | 1203篇 |
1990年 | 1072篇 |
1989年 | 1115篇 |
1988年 | 998篇 |
1987年 | 936篇 |
1986年 | 860篇 |
1985年 | 735篇 |
1984年 | 473篇 |
1983年 | 390篇 |
1982年 | 210篇 |
1981年 | 177篇 |
1980年 | 140篇 |
1979年 | 232篇 |
1978年 | 108篇 |
1977年 | 100篇 |
1973年 | 103篇 |
1971年 | 100篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
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
992.
为观察苏林酸对结肠腺癌HT-29细胞有无促凋亡作用,采用流式细胞仪检测、DNA电泳和透射电镜观察苏林酸对HT-29细胞的促凋亡作用。结果:流式细胞式、DNA电泳和透射电镜观察均显示苏林酸可诱导HT-29细胞凋亡,且具有时间和剂量依赖性。用0.3mmol/L、0.6mmol/L和1.2mmol/L苏林酸处理48小时,凋亡细胞分别占5.8%、7.6%和11.7%,处理72小时则分别升为12.5%、15 相似文献
993.
柱切换HPLC法测定腹水中左旋氧氟沙星的含量 总被引:1,自引:0,他引:1
目的:应用柱切换HPLC技术直接测定腹水中左旋氧氟沙得含量。方法:采用磷酸二氢钾缓冲溶液(PH2.2)-0.05mol/L四丁溴化化铵(100:4)为预处理流动相,经μBondapak C18柱预处理后,切换到Irregular_HC18分析柱,以甲醇-磷权二氢钾缓冲溶液(PH2.2)-0.05mol/L四丁基溴化铵(30:70:4)为分析流动相进行分离测定,紫外线皮长为294nm。结果:左旋氧氟 相似文献
994.
Objective To evaluate apoptosis in lupus nephritis and the relationship between the existe nce of apoptotic cells in renal tissue and histopathological or clinical changes .Methods Apoptosis was detected by in situ nick-end labeling techniques (TUNEL) in renal biopsies from 25 patients with type Ⅳ lupus nephritis (LN), 12 patients with I gA nephropathy IgAN, 4 patients with idiopathic mesangioproliferative glomerulon ephritis (MsPGN) and 3 patients with acute poststreptococcal glomerulonephritis (APGN).Normal renal tissue obtained at nephrectomy for hypernephroma in 4 adul ts was used as control.Proliferating cells were identified by proliferating ce ll nuclear antigen (PCNA) in these patients. Results Compared to other proliferative glomerulo-nephritis and controls, the patients w ith lupus nephritis had less apoptotic cells, a higher ratio of PCNA+ cells/TdT+ cells (P/T) in renal tissues; and their P/T ratio in glomeruli and tubuloin terstitium correlated with the chronicity index, r=0.4983 (P=0.0132), r=0.8399 (P<0.001), r=0.6614 (P=0.0033), respectively.P/T ratios in the glomerulus and tubule had a positive correlation with 24-hour uri nary protein, r=0.8554 (P<0.001) and r=0.7134 (P=0.001); and a negative correlation with creatinine clearance (Ccr), r=-0.4880 (P=0 .0133) and r=-0.7229 (P=0.001), which in tubules positively corre lated with serum creatinine (Scr), r=0.4107 (P=0.0414).Conclusions Apoptosis is reduced in proliferative lupus nephritis.Intense proliferation wi thout a commensurate increase in apoptosis is a possible mechanism that leads to chronic progressive renal histopathological changes. 相似文献
995.
过氧化物诱导LO2细胞凋亡时Fas mRNA表达及Ca^2+流变化的单 … 总被引:1,自引:0,他引:1
探讨过氧化物所致肝细胞凋亡时Fas基因表达与Ca^2+流变化的相互关系。方法应用全细胞膜片错单细胞逆转录聚合酶链反应技术进行H2O2诱导人类正常肝细胞LO2细胞FasmRNA表达的单细胞分析,应用全细胞膜片错显微荧光单细胞胞浆游离钙浓度测量技术、流式细胞术、扫描电镜观察同期瞬时Ca^2+流变化及早期凋亡(Annexin-V)细胞指数和细胞膜变化。结果H2O2作用2h单个LO2细胞电泳图分析可见Fa 相似文献
996.
Changes in tissue metals after cadmium intoxication and intervention with chlorpromazine in male rats 总被引:8,自引:0,他引:8
Yang XF Wang SY Zhao RC Ao SQ Xu LC Wang XR 《Biomedical and environmental sciences : BES》2000,13(1):19-25
Cadmium(Cd),one of the most dangerous heavy metals,has a very similar ionic radius to calcium(Ca),The interference of cadmium in calcium homeostasis may play an important role in cadmium toxicity.Recent reports indicate that calmodulin(CaM) inhibitors such as trifluoperazine and chlorpromazine(CPZ) could protect rodents against cadmium toxicity,It was also reported that pretreatment of mice with zine(Zn)could reduce the adverse effects induced by cadmium.The aim of this study is to determine whether Cd changes the balance of other essential metals such as Zn and copper(Cu) in rat tissues,and whether CPZ can reverse these changes which are induced by cadmium intoxication.Adult male Sprague-Dawley(SD) rats were injected intraperitoneally(ip) with cadmium chloride(CdCl2)(0.2,0.4,0.8mg Cd/kg body wight) alone and 0.4mg Cd/kg in association with CPZ(5mg/kg) daily for a week.The control animals were injected with normal saline only.The results showed that the cadmium content in the liver,kidney,and testis increased significantly with a dose-response relationship.Cadmium treatment markedly increased the Zn and Ca content in some of the tissues,Hepatic and renal metallothionein(MT) increased significantly after cadmium intoxication,CPZ treatment,howerver,reduced cadmium content in liver,but not blood and kidney.CPZ seemed to decrease the content of MT in liver and significantly increase the amounts of MT in kidney.These data suggest that the intervention of cadmium with tissue essential metals may play a role in cadium toxicity in rats,and calmodulin inhibitors to some extent can reduce the adverse effect of cadmium by decreasing the cadmium load in tissues and reversing the unbalance of essetial metals. 相似文献
997.
目的:探讨肾细胞癌中FHIT基因的改变及意义。方法:用RT-PCR及Southern印迹杂交法检测肾细胞癌及其细胞系中FHIT基因转录本,并观察其基因组的改变。结果:约8.3%(2/24)肾细胞癌有异常转录本;其中一株细胞系cDNA在用外引物扩增时,只有一个变小的FHIT基因异常转录本;用内引物扩增时,FHIT基因转录本完全缺失。约20%(5/24)肾细胞癌FHIT基因区域的基因组DNA出现重排。 相似文献
998.
中药“拮新康”对白血病细胞凋亡的影响 总被引:2,自引:0,他引:2
为探讨中药“拮新康”对白血病细胞凋亡的影响。采用形态学及DNA凝胶电泳方法观察其对白血病细胞株HL-60及K562细胞凋亡的影响,结果示:①电镜观察可见凋亡细胞和凋亡小体,DNA凝胶电泳可见典型的梯形带改变;②一定浓度范围内的拮新康经适当作用时间后可诱导白血病HL-60,K562细胞凋亡,但诱导K562细胞凋亡所需时间较HL-60长且剂量较大。提示拮新康可诱导白血病细胞凋亡,与剂量和时间有一定的关 相似文献
999.
ACEI治疗肾性高血压和对肾机能的保护作用 总被引:3,自引:0,他引:3
OBJECTIVE: To explore the influence of angiotensin-converting enzyme inhibitors (ACEI) on plasma endothelin (ET-1), nitric oxide (NO) and renal function in renal-hypertension patients. METHODS: Sixty renal-hypertension patients (Group II) were treated with ACEI (lotensin) for 10 weeks then we measure their blood pressure (BP), plasma ET-1, NO and renal functions (BUN, Scr and proteinuria) before and after the treatment. Thirty healthy persons (Group I) acted as control. RESULTS: The level of plasma ET-1 was higher and plasma NO was lower in Group II than those in Group I. After the treatment of ACEI plasma ET-1 and proteinuria were decreased (P < 0.01), and NO increased in Group II significantly (P < 0.01), while BUN and Scr decreased in abnormal-renal function patients (Group II2) (P < 0.05, P < 0.01). CONCLUSION: The Study indicates that: ACEI is effective to renal hypertension; it decreases plasma ET-1 and increases NO in the renal hypertension patients; ACEI may play an important role in protection of renal functions and prolonging the chronic renal failure. 相似文献
1000.
目的分析更年期综合征的影响因素.方法对苏州市一丝织厂105名≥45岁的女职工进行了问卷式登记调查.对其中71名作了单侧髋骨X线摄片,了解骨质疏松情况.按不同组别对各组的更年期综合征积分均值进行了统计分析.结果年龄、药物、手术、月经周期紊乱和肥胖对更年期综合征有显著影响,骨质疏松对更年期综合征有影响,生育、饮食习惯与婚姻状况影响不大.结论更年期综合征受多种因素影响. 相似文献