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   61613篇
  免费   4977篇
  国内免费   2051篇
耳鼻咽喉   710篇
儿科学   1186篇
妇产科学   1201篇
基础医学   6672篇
口腔科学   1222篇
临床医学   6944篇
内科学   11735篇
皮肤病学   1107篇
神经病学   3575篇
特种医学   1449篇
外国民族医学   6篇
外科学   6866篇
综合类   7337篇
现状与发展   2篇
一般理论   9篇
预防医学   5255篇
眼科学   1393篇
药学   5642篇
  64篇
中国医学   2641篇
肿瘤学   3625篇
  2024年   180篇
  2023年   829篇
  2022年   1937篇
  2021年   2954篇
  2020年   2158篇
  2019年   1977篇
  2018年   2187篇
  2017年   1955篇
  2016年   1681篇
  2015年   2470篇
  2014年   3231篇
  2013年   3715篇
  2012年   5528篇
  2011年   5607篇
  2010年   3760篇
  2009年   3212篇
  2008年   3968篇
  2007年   3916篇
  2006年   3364篇
  2005年   3039篇
  2004年   2365篇
  2003年   2242篇
  2002年   1833篇
  2001年   603篇
  2000年   505篇
  1999年   473篇
  1998年   367篇
  1997年   354篇
  1996年   304篇
  1995年   236篇
  1994年   193篇
  1993年   148篇
  1992年   154篇
  1991年   109篇
  1990年   120篇
  1989年   105篇
  1988年   86篇
  1987年   76篇
  1986年   69篇
  1985年   58篇
  1984年   49篇
  1983年   47篇
  1982年   60篇
  1981年   67篇
  1980年   38篇
  1979年   44篇
  1978年   21篇
  1977年   33篇
  1976年   31篇
  1973年   19篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Amyloidosis is a systemic disease that usually occurs in the gastrointestinal tract or in muscular or adipose tissue. Primary amyloidosis of the urinary bladder is a rare disease that can mimic bladder cancer on cystoscopic examination as well as in its clinical presentation of painless gross hematuria. This report describes a 49-year-old male with repeated painless gross hematuria, who underwent transurethral resection of a suspected bladder tumor. Pathologic examination revealed papillary urothelial hyperplasia with vascular ectasia and no signs of malignancy. Massive gross hematuria occurred 2.5 years later. Cystoscopy showed multiple papillary lesions with yellowish-brown submucosal plaques on the posterior bladder wall. A second transurethral tumor resection was performed and histologic examination revealed plasma cell infiltration and eosinophilic amorphous deposits in the subepithelial stroma and vascular wall. The deposits were positive for Congo red and apple-green birefringence under polarized light examination but negative for Masson's trichrome stain, indicating that they were not fibrotic in nature. Hence, the diagnosis of amyloidosis of the urinary bladder was confirmed. Screening for amyloidosis was negative in other organ systems and the patient has remained disease-free up to the last follow-up 4 years after the second transurethral resection. Amyloidosis should be considered in the differential diagnosis of patients with recurrent hematuria who have symptoms characteristic of bladder cancer but negative pathologic study for malignancy. Correct diagnosis relies on clinical alertness and the use of a special staining technique during pathologic examination.  相似文献   
72.
目的 :探讨系统性红斑狼疮 (SLE)女性患者血清肿瘤标志物CA12 5 ,CA199含量变化及临床意义。方法 :用化学发光法测定 30例正常女性和 38例SLE女性患者血清中CA12 5 ,CA199含量。结果 :正常组CA12 5含量为 11.14± 6 .4 8U/ml,CA199含量为 3.75± 2 .89U/ml;SLE组CA12 5 ,CA199分别为 2 2 .5 6± 2 0 .4 6U/ml,9.5 7± 9.34U/ml。SLE患者CA12 5 ,CA199阳性率分别为 2 1.1% ,7.89%。结论 :SLE患者血清CAl2 5 ,CA199含量较正常组增高 (P <0 .0 5 )。CA12 5 ,CA199在SLE女性患者中可出现阳性 ,对临床诊断SLE有一定价值。  相似文献   
73.
We studied NK cell function in eight patients with pathological hyperprolactinemia by measuring51Cr release by K562 cells exposed to their mononuclear cells and found it decreased compared to normal controls (P<0.01). Bromocriptine (BrC) treatment corrected NK function but also made it more efficient at 12:1 than at 25:1 or 50:1 effector:target ratios (ANOVA;P=0.01). The study of NK cell function in agarose revealed that its decrease in hyperprolactinemia is due to their low active binding to target cells, active killing, and recycling capacity. BrC tended to correct them but also increased recycling capacity to levels higher than those of controls (P<0.05). Sequential studies in three hyperprolactinemic patients before and after BrC showed correction of NK function within 1 week but its increased efficiency at the 12:1 effector:target ratio required 8 weeks. We conclude that hyperprolactinemia decreases NK cell function. BrC corrects this by decreasing prolactin levels but also makes NK function more efficient by increasing the capacity of NK cells to recycle after killing.  相似文献   
74.
目的 探讨碘伏清洗外耳道的效果。方法 将耳部疾病患者100例(127耳)随机分为观察组和对照组各50例,观察组采用0.5%碘伏液清洗外耳道,对照组采用3%过氧化氩液清洗外耳道。两组其他操作方法相同。结果 两组治疗效果比较,差异无显著性意义(P〉0.05),但观察组外耳道清洗后耳痛发生率显著低于对照组(P〈0.01)。结论 0.5%碘伏液清洗外耳疗效较好,对皮肤黏膜无刺激,可减轻患者痛苦,是比较满意的外耳道洗耳液。  相似文献   
75.
Objectives:  Bipolar disorder is a severe illness that is associated with suicidal behavior. A biological predictor of highly lethal suicide attempts in patients with bipolar disorder would be valuable. We hypothesized that cerebrospinal fluid (CSF) monoamine metabolite levels are related to lethality of suicide attempts in bipolar patients and examined the relation between CSF 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA), and 3-methoxy-4-hydroxyphenylglycol (MHPG) levels and maximum lethality of suicide attempts at baseline and during a 2-year follow up.
Methods:  Twenty-seven bipolar depressed patients participated in the study. Demographic and clinical parameters were examined and recorded. Lumbar punctures were performed and CSF 5-HIAA, HVA, and MHPG were assayed by high-performance liquid chromatography with electrochemical detection. Following discharge, patients were evaluated after 3 months, 1 year, and 2 years. Each follow-up interview included an in-depth assessment of suicidal behavior during the intervening time period.
Results:  Six subjects made suicide attempts during the 2-year follow-up. Bipolar patients who attempted suicide during the follow-up period had higher aggression and hostility scale scores compared to bipolar subjects who did not make a suicide attempt during the follow-up period. CSF 5-HIAA, HVA, and MHPG levels were negatively correlated with the maximum lethality of suicide attempts during the 2-year follow-up period.
Conclusions:  Our finding is the first observation that CSF monoamine metabolite levels may be predictors of lethality of suicide attempts in patients with bipolar disorder. Further studies are necessary to answer the question whether CSF monoamine metabolite levels are clinically useful biochemical predictors of highly lethal suicide attempts or completed suicides.  相似文献   
76.
77.
The present work tries to establish the antioxidant capacity of the peripheral nervous tissue of the rat, in terms of the enzymatic activities present in this tissue that either prevent the formation of activated species as the semiquinone radical (DT-diaphorase), protect against activated oxygen species (superoxide dismutase, glutathione peroxidase), conjugate natural toxic products or xenobiotics (glutathione S-transferases, especially the activity conjugating 4-hydroxy-nonenal), or complete the glutathione system metabolism (glutathione disulfide reductase, γ-glutamyl transpeptidase). All the activities studied are lower in this tissue than they are in liver, except for γ-glutamyl transpeptidase. The relevance of the results obtained and its possible relationship with different neuropathies is discussed. It is concluded that the peripheral nervous tissue is by far less protected than the liver against oxidative damage.  相似文献   
78.
Melatonin reduces nitric oxide synthase activity in rat hypothalamus   总被引:2,自引:0,他引:2  
Abstract: In this report, rat hypothalamic nitric oxide synthase (NOS) activity is shown to be partially inhibited by physiological concentrations of the pineal hormone melatonin. In vitro studies demonstrate that 1 nM melatonin, which approximates the physiological concentration of the hormone at night, significantly inhibited NOS activity. In vivo studies show that administering melatonin or collecting the hypothalamus from animals at night, when endogenous melatonin levels are elevated, results in a significant decrease of NOS activity. Results also show that calmodulin may be involved in this process since its presence in the incubation medium prevents the inhibitory effect of melatonin on NOS activity.  相似文献   
79.
80.
Immunology     
A selection of interesting papers that were published in the two months before our press date in major journals most likely to report significant results in immunology.  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