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   36851篇
  免费   3734篇
  国内免费   1591篇
耳鼻咽喉   356篇
儿科学   673篇
妇产科学   553篇
基础医学   3531篇
口腔科学   710篇
临床医学   4536篇
内科学   5312篇
皮肤病学   583篇
神经病学   2086篇
特种医学   1052篇
外国民族医学   2篇
外科学   3402篇
综合类   5726篇
现状与发展   17篇
一般理论   25篇
预防医学   3687篇
眼科学   996篇
药学   4120篇
  54篇
中国医学   2446篇
肿瘤学   2309篇
  2024年   169篇
  2023年   521篇
  2022年   1419篇
  2021年   1839篇
  2020年   1500篇
  2019年   1189篇
  2018年   1347篇
  2017年   1330篇
  2016年   1186篇
  2015年   1614篇
  2014年   1928篇
  2013年   2106篇
  2012年   3138篇
  2011年   3216篇
  2010年   2334篇
  2009年   1988篇
  2008年   2468篇
  2007年   2287篇
  2006年   2038篇
  2005年   1843篇
  2004年   1356篇
  2003年   1257篇
  2002年   1024篇
  2001年   401篇
  2000年   349篇
  1999年   237篇
  1998年   254篇
  1997年   198篇
  1996年   142篇
  1995年   125篇
  1994年   129篇
  1993年   89篇
  1992年   108篇
  1991年   108篇
  1990年   87篇
  1989年   62篇
  1988年   63篇
  1987年   57篇
  1986年   70篇
  1985年   55篇
  1984年   59篇
  1983年   63篇
  1982年   70篇
  1981年   46篇
  1980年   39篇
  1979年   25篇
  1978年   36篇
  1977年   32篇
  1974年   18篇
  1973年   16篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
目的建立一种操作简便、高效的测定脑组织中去甲肾上腺素(NA)、肾上腺素(AD)、多巴胺(DA)、3,4二羟基苯乙酸(DOPAC)及高香草酸(HVA)的方法,为有关药物作用机理的研究提供实验手段.方法以有机溶剂提取,高效液相色谱--电化学检测器(HPLC-EC)测定大鼠纹状体、皮质、下丘脑NA、AD、DA、DOPAC及HVA的含量.结果测得NA、AD、DA、DOPAC及HVA的绝对回收率依次分别为:80.3%±12.4%,86.5%±14.3%,90.3%±12.1%,89.5%±17.2%、87.6%±[13].2%.线性范围0.2~20ng,批内与批间变异系数分别小于8%及10%.结论该方法具有简便、迅速、回收率较高的特点,便于实验室应用.  相似文献   
23.
For more than two decades, the International Narcotic Control Board (INCB) has tried to stop harm reduction and its HIV prevention programs. This posture is based on a fundamental misunderstanding of their responsibilities and of drug addiction itself – i.e. as a public health and clinical care matter made criminal by decree. A recent focal point for the Board's action has been rejecting the use of supervised injection facilities to reduce morbidity and mortality of drug injectors. They single out individual countries and attempt to bully them into rejecting such programs under the banner of the United Nations (falsely) and in the name of international treaties. Their unrelenting and unjustified badgering of signatories to the international treaties that established the INCB is not only unjustified; it is an affront to one of the core purposes of the Board itself: to ensure adequate medical supplies and safe use of controlled substances. The INCB's ill-conceived obsession with intravenousaddiction as a crime flies in the face of the medical view and policies of the World Health Organization and the universally endorsed principles of the General Assembly of the United Nations.  相似文献   
24.
目的:认识睾丸微石症(TM)的临床意义和诊断方法。方法:回顾性报告2例TM病例的临床资料,结合文献进行讨论。结果:2例分别因左精索静脉曲张和附睾炎就诊的患者行阴囊超声检查时发现睾丸内散在多发点状强回声,如针尖样,1~2mm,后无声影。分别诊断为局部TM、左精索静脉曲张和TM,左附睾炎。甲胎蛋白、人绒毛膜促性腺激素、乳酸脱氢酶和睾酮等检查均正常。对睾丸微石症未做特殊处置,随访6~8个月,体检和睾丸瘤标未见异常,阴囊超声睾丸图像无特征性改变。结论:TM是一种少见、无明显临床症状、相对稳定的疾病。多因阴囊其他疾病行超声检查时偶然发现,其是否属于癌前病变尚有争议,但是定期随访和阴囊超声检查是必要的。  相似文献   
25.
目的:探讨血管紧张素Ⅱ(AngⅡ)及其Ⅰ型、Ⅱ型受体阻断剂和钙调神经磷酸激酶(CaN)的阻滞利环胞素A(CsA)对增生性瘢痕来源的成纤维细胞纤维连接蛋白mRNA和蛋白表达的作用。方法:体外分离培养增生性瘢痕成纤维细胞,分别将一定浓度的AngⅡ(10^-9~10^-5mmol/L),和AngⅡ10^-6mmol/L加上不同阻滞剂losartan、PD123319、环胞素A(浓度均为10^-5mmol/L)加入细胞培养液中刺激48h,分别采用逆转录聚合酶链反应(RT—PCR)及Westernblot印迹方法检测增生性瘢痕成纤维细胞纤维连接蛋白(FN)的mRNA及蛋白表达。结果:体外成功地培养增生性瘢痕成纤维细胞。经AngⅡ刺激48h后,FN mRNA和蛋白表达量明显增高,增高程度与AngⅡ浓度呈正比;加入losaartan和环胞素A后,FN原mRNA和蛋白表达量较单用AngⅡ组下降,而加入PD123319后,FNmRNA和蛋白表达量较单用AngⅡ组无明显改变。结论:AngⅡ可促增生性瘢痕成纤维细胞的FN合成,可能在增生性瘢痕的发展过程中起重要作用,该作用主要通过AngⅡ的Ⅰ型受体介导完成,该作用可能与CaN信号通路有关。  相似文献   
26.
Androgens are important regulators of bone and prostate health in elderly men. The role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in men is unclear. We show that specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. INTRODUCTION: Androgens are important regulators of bone and prostate health in elderly men. Local synthesis and degradation of androgens are likely to be important parameters of biological action of androgens in androgen-responsive tissues. The aim of this study was to determine the role of serum levels of glucuronidated androgen metabolites as predictors of BMD and prostate volume in elderly men. MATERIALS AND METHODS: A subsample of the population-based Swedish part of the MrOS study (n = 631, average age = 75.9 years) was investigated. Bone parameters were measured using DXA. Serum levels of total testosterone (T) and dihydrotestosterone (DHT) were measured by gas chromatography/mass spectroscopy (GC-MS); androstane-3alpha,17beta-diol-3glucuronide (3G) and androstane-3alpha,17beta-diol-17glucuronide (17G) were measured by liquid chromatography/mass spectroscopy. Prostate volume (n = 159) was measured by transrectal ultrasound. RESULTS: The general pattern is that two of the glucuronidated androgen metabolites, namely 17G and 3G, are stronger positive predictors of BMD than the bioactive androgens (T and DHT). In addition, 17G is a clear positive predictor of prostate volume, explaining 4.5% of the variance in prostate volume, whereas the bioactive androgens do not display any association with prostate volume. CONCLUSIONS: Serum levels of specific glucuronidated androgen metabolites predict BMD and prostate volume in elderly men. Future studies should determine if the glucuronidated androgen metabolites also reflect other biological correlates of androgenic activity, including prostate cancer, and if low levels might be a marker of general androgen deficiency in men.  相似文献   
27.
Impaired ability to conduct daily activities is a diagnostic criterion for dementia and a determinant of healthcare services utilization and caregiver burden. What predicts decline in instrumental activities of daily living (IADLs) is not well understood. This study examined measures of episodic memory, executive function, and MRI brain volumes in relation to baseline IADLs and as predictors of rate of IADL change. Participants were 124 elderly persons with cognitive function between normal and moderate dementia both with and without significant small vessel cerebrovascular disease. Random effects modeling showed that baseline memory and executive function (EXEC) were associated with baseline IADL scores, but only EXEC was independently associated with rate of change in IADLs. Whereas hippocampal and cortical gray matter volumes were significantly associated with baseline IADL scores, only hippocampal volume was associated with IADL change. In a model including cognitive and neuroimaging predictors, only EXEC independently predicted rate of decline in IADL scores. These findings indicate that greater executive dysfunction at initial assessment is associated with more rapid decline in IADLs. Perhaps executive function is particularly important with respect to maintaining IADLs. Alternatively, executive dysfunction may be a sentinel event indicating widespread cortical involvement and poor prognosis.  相似文献   
28.
肱骨干骨折--髓内钉与钢板固定的比较   总被引:1,自引:1,他引:0  
总体而言,这些报道提示:采用髓内钉治疗肱骨干骨折较采用钢板带来更多的并发症,尤其是采用顺行人路。同时,这些报道没有提供确切的证据证明何种方法在骨折愈合、减少感染或上肢总体功能上优于另一种。  相似文献   
29.
小剂量长春新碱对小鼠M1细胞的分化诱导作用研究   总被引:1,自引:0,他引:1  
目的:利用培养小鼠髓性白血病(M1细胞)来检测小剂长春新碱(VCR)对小鼠M1细胞分化诱导功能。方法:分观察组对照组,观察组使用VCR1次5ug后进行吞噬功能实验,及对细胞形态的观察与空白对照组比较。结果:发现使用小剂量长春新碱后小鼠M1细胞诱变细胞增多,吴噬功能增强,结论:说明小剂量长春新碱对培养小鼠M1细胞有一定诱导功能,诱导其向粒细胞、吞噬细胞方向转化,在临床上白血病的治疗有一定的作用。  相似文献   
30.
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