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   99858篇
  免费   6661篇
  国内免费   3055篇
耳鼻咽喉   663篇
儿科学   2578篇
妇产科学   1256篇
基础医学   15272篇
口腔科学   1944篇
临床医学   7198篇
内科学   16757篇
皮肤病学   2081篇
神经病学   7284篇
特种医学   1617篇
外国民族医学   15篇
外科学   8834篇
综合类   10413篇
现状与发展   15篇
一般理论   4篇
预防医学   7141篇
眼科学   1493篇
药学   14569篇
  11篇
中国医学   4608篇
肿瘤学   5821篇
  2023年   1542篇
  2022年   3060篇
  2021年   3383篇
  2020年   2885篇
  2019年   4331篇
  2018年   4141篇
  2017年   3362篇
  2016年   2806篇
  2015年   3207篇
  2014年   5050篇
  2013年   6089篇
  2012年   5146篇
  2011年   6135篇
  2010年   5021篇
  2009年   4526篇
  2008年   4261篇
  2007年   4170篇
  2006年   3527篇
  2005年   3212篇
  2004年   2859篇
  2003年   2573篇
  2002年   2070篇
  2001年   1818篇
  2000年   1514篇
  1999年   1408篇
  1998年   1149篇
  1997年   1100篇
  1996年   939篇
  1995年   848篇
  1994年   783篇
  1993年   662篇
  1992年   595篇
  1991年   560篇
  1990年   466篇
  1989年   398篇
  1988年   382篇
  1986年   300篇
  1985年   1334篇
  1984年   1679篇
  1983年   1247篇
  1982年   1433篇
  1981年   1331篇
  1980年   1055篇
  1979年   1039篇
  1978年   776篇
  1977年   618篇
  1976年   726篇
  1975年   596篇
  1974年   420篇
  1973年   422篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Microvascular decompression (MVD) is an effective and safe treatment in hemifacial spasm (HFS). Postoperative evaluations are usually made by neurosurgeons. Follow-up studies performed by neurologists and postoperative quality of life (QoL) investigations are lacking. All 25 HFS patients operated with MVD in our centre between 2000 and 2004 were evaluated with the recently validated HFS-7 scheme, extended with the item 'sleep disturbance due to HFS' (HFS-8). The patients underwent a careful neurological examination median 3 years after the operation. The evaluation focused on clinical aspects, changes in blood pressure and time until observable effect of MVD. The evaluation of HFS-7 questionnaire and the extended form (HFS-8) showed significant improvement in QoL after MVD. Neurological outcome was in almost all cases excellent or good. Eleven (44%) patients had no neurological deficits at all. Only one patient had serious complications with ipsilateral facial palsy, deafness, balance problems and vertigo. The other patients had minor neurological findings or symptoms. Eighteen (72%) patients experienced early effect within 3 months after MVD; seven (28%) patients had late effect between 6 and 14 months. Median age of the patients with late effect (62.6 years) was significantly higher than in those with early effect (52.7 years).  相似文献   
72.
Background: The C‐100 colour vision test has been shown to have a high validity for diagnosing the type of red‐green colour vision defect, however, there is little information on the repeatability of the test. This study examines the repeatability of the C‐100 in classifying the colour vision defect as either protan or deutan. Methods: The C‐100 was administered on two occasions to 58 subjects with congenital red‐green colour vision defects: The sessions were separated by a minimum period of 10 days. Results: The repeatability of the C‐100 was high with a kappa coefficient of agreement for diagnosis of 0.96. The few discrepancies were misclassifying protans as deutans. Conclusion: The C‐100 is a highly repeatable test in terms of separating protans from deutans. However, if a discrepancy occurs, it is more likely to be a protan misclassified as a deutan rather than vice versa.  相似文献   
73.
A patient with neutropenia and life-threatening infections secondary to T-γ lymphoproliferative disease, who did not respond to treatment with recombinant human G-CSF (filgrastim), was treated with filgrastim plus cyclosporine A (CyA). The patient achieved a good response in the absolute neutrophil count and subsequently required a dose reduction in the filgrastim. The patient was eventually discontinued from the CyA but continues on filgrastim alone. While on therapy, the large granular lymphocytes disappeared from the circulation and the beta-TCR rearrangement, which was present prior to beginning therapy, became undetectable. The patient had no significant toxicity to the CyA or the filgrastim and he has not experienced any serious infections or required hospitalization. Filgrastim has proven to be relatively nontoxic and of some benefit to patients with this disease and should probably be utilized first when treatment is necessary. However, if improvement is not observed, these findings suggest that a trial of the combination of CyA plus filgrastim may be beneficial.  相似文献   
74.
Low-frequency stimulation is associated with long-term depression (LTD) of synaptic efficacy in various brain structures. Like long-term potentiation (LTP), homosynaptic LTD in area CA1 of the hippocampus appears to require NMDA receptor activation, changes in postsynaptic calcium concentration and phospholipase A2 (PLA2) activation. Arachidonic acid (AA) is released after the activation of calcium-dependent phospholipases and free AA is rapidly metabolized to a family of bioactive products (the eicosanoids) which are thought to be both intracellular and extracellular messengers. In the present study, we investigated the involvement of the cyclooxygenase and lipoxygenase pathways of AA metabolism in the formation of homosynaptic LTD in the rat hippocampus. Stimulation at 1 Hz for 15 min was used to produce homosynaptic depression in area CA1 of hippocampal slices. LTD induction was partially blocked by bromophenacyl bromide (50–100 μM), a selective PLA2 inhibitor, and by the a nonselective lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA; 100 μM). In contrast, the specific cyclooxygenase blocker indomethacin (100 μM) did not significantly reduce hippocampal LTD. Since NDGA interferes with LTD formation, we examined whether specific inhibitors of 5- and 12-lipoxygenases were capable of blocking LTD expression. The 12-lipoxygenase inhibitor baicalein at a concentration of 50 μM reduced LTP formation when given in the bath, an effect that was less pronounced with the 5-lipoxygenase inhibitor AA-861. These data suggest that the activation of endogenous PLA2 and the formation of 12-lipoxygenase metabolites of AA may be important factors controlling the expression of hippocampal LTD.  相似文献   
75.
To assist in the selection of a preferable vitamin A deficiency control policy, a model has been developed to organize information on program costs and program-related effects. The model was designed to compare three approaches: (1) diet modification; (2) fortification of processed foods; and (3) periodic large doses. Health effects projected are rates of specific eye pathologies associated with vitamin A deficiency (xerophthalmia), and mortalities within age cohorts. Effectiveness is calculated as a function of coverage, biological efficacy, and incidence of vitamin A deficiency. The model was applied to data from the Province of West Java in Indonesia. The results of this application suggest that funding level considerations are an important factor in selecting a preferred control strategy. In addition to determining the relative resource requirements of alternative interventions aimed at reducing the morbidity and mortality effects of vitamin A deficiencies, the model, using marginal cost and marginal effectiveness information, can serve as a guide to the most efficient allocation of resources for each type of intervention.  相似文献   
76.
本文研究了竹红菌甲素(简称甲素)对S-180肿瘤细胞膜的作用。结果表明,甲素结合光照可引起S-180肿瘤细胞膜蛋白质交联、脂质过氧化产物MDA含量增加。但在SDS-PAGE分析中观察到的高分子蛋白质交联带并非由MDA所引起。甲素同样可引起小牛胸腺组蛋白光氧化、发生分子交联,并可敏化色氨酸、酪氨酸和组氨酸的无氧化。  相似文献   
77.
应用0.5%环孢霉素A(cyclosporin A,CsA)滴眼治疗穿透性角膜移植术后发生免疫排斥患者16例(16只眼),治愈9只眼,好转6只眼,无效1只眼。随访5~24个月,其中2只眼因停药复发,1只眼于拆线后复发,继续用药或增加给药次数后治愈。研究表明0.5%CsA滴眼剂治疗术前移植床条件较好,角膜移植术后发生免疫排斥的病例可得到良好疗效;而对术前移植床条件较差,角膜移植术后发生免疫排斥的病例有一定的疗效。作者对眼局部应用CsA治疗角膜移植排斥的疗效和作用机理进行了讨论。  相似文献   
78.
Superoxide release in neutrophils and sera levels of interleukin 8 (IL-8) were determined in 15 patients with complicated acute myocardial infarction (MI) and 15 patients with uncomplicated MI. All patients showed increased superoxide release in unstimulated and stimulated neutrophils compared with healthy control subjects, indicating priming of these cells. Superoxide release of unstimulated or stimulated neutrophils was found to be significantly higher in patients with complicated MI than in patients with uncomplicated MI. Thrombolytic therapy did not affect the rates of superoxide release. The neutrophil chemoattractant/activator IL-8 was detected in the sera of all patients, with significantly higher levels in those with complicated MI. The highest levels of IL-8 were detected at admission to the Coronary Care Unit and significantly decreased thereafter, suggesting its contribution to neutrophil-mediated tissue injury. The high levels of IL-8 may be one of the major contributors to the priming of neutrophils in these patients.  相似文献   
79.
1. The effects of sarafotoxin S6c (S6c), a selective endothelin ETB receptor agonist, on renal haemodynamics and urine formation were examined in anaesthetized dogs. 2. Intrarenal arterial infusion of S6c at a rate of 1 or 5 ng/kg per min produced a transient increase in renal blood flow (RBF), with no change in systemic blood pressure and heart rate; RBF then decreased gradually to below the basal value. There were significant and dose-dependent increases in urine flow and free water clearance and decreases in urine osmolality during S6c infusion, whereas urinary excretion of sodium and glomerular filtration rate (GFR) remained unchanged. Simultaneously, S6c administration elicited a marked increase in urinary excretion of nitric oxide (NO) metabolites, N02? and N03? (UNO*V). 3. In dogs simultaneously administered S6c (5 ng/kg per min) and iVG-nitro-L-arginine (NOARG; 40 (jig/kg per min), a NO synthase inhibitor, the renal vasodilator effect of S6c was abolished and marked reductions in RBF and GFR were observed. The S6c-induced diuretic action was not affected by NOARG. In the presence of NOARG, there was a small amount of UNOxV at the basal level and the administration of S6c did not increase UNOxV. 4. These results suggest that an intrarenal arterial infusion of S6c enhances the production of NO in the kidney and that this enhancement contributes to the peptide-induced renal vasodilation. In contrast, it is unlikely that S6c-induced water diuresis is related to NO production stimulated by this peptide.  相似文献   
80.
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