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   142737篇
  免费   10467篇
  国内免费   3987篇
耳鼻咽喉   1291篇
儿科学   2804篇
妇产科学   2653篇
基础医学   9219篇
口腔科学   3911篇
临床医学   16735篇
内科学   20255篇
皮肤病学   2423篇
神经病学   8969篇
特种医学   4594篇
外国民族医学   40篇
外科学   14175篇
综合类   20462篇
现状与发展   23篇
一般理论   2篇
预防医学   5947篇
眼科学   2344篇
药学   11698篇
  84篇
中国医学   11707篇
肿瘤学   17855篇
  2024年   351篇
  2023年   2452篇
  2022年   4509篇
  2021年   6127篇
  2020年   5748篇
  2019年   5239篇
  2018年   4867篇
  2017年   5319篇
  2016年   5652篇
  2015年   5491篇
  2014年   9780篇
  2013年   12375篇
  2012年   8148篇
  2011年   8777篇
  2010年   7275篇
  2009年   6702篇
  2008年   6550篇
  2007年   6952篇
  2006年   6287篇
  2005年   5585篇
  2004年   4583篇
  2003年   4098篇
  2002年   3361篇
  2001年   2986篇
  2000年   2517篇
  1999年   2018篇
  1998年   1691篇
  1997年   1467篇
  1996年   1268篇
  1995年   1175篇
  1994年   984篇
  1993年   753篇
  1992年   683篇
  1991年   630篇
  1990年   548篇
  1989年   475篇
  1988年   481篇
  1987年   408篇
  1986年   354篇
  1985年   445篇
  1984年   379篇
  1983年   274篇
  1982年   303篇
  1981年   283篇
  1980年   208篇
  1979年   186篇
  1978年   141篇
  1977年   83篇
  1976年   75篇
  1975年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
We evaluated nitric oxide induction in antitumor therapy consisting of anti–CD3 monoclonal antibody (anti–CD3) and interleukin–2 (IL–2), then determined the effect of nitric oxide reduction with L–NG–monomethyl arginine (LNMA) on the therapeutic methods. Female C57BL/6 mice, MCA102 (a non immunogenic, NK–resistant murine fibrosarcoma cell line), and 145–2C11 (hamster anti–murine–CD3 mAb) were utilized in an experimental hepatic metastasis model developed by injecting a tumor cell suspension into the spleen of mice. A marked increase in serum NO2+ NO1 was observed at 19 hours after anti–CD3 (10 μ, IV) and additional IL–2 administrations (40times101 U, twice, If) induced a further increase. The NO2, + NO3- elevation in spot urine in the combination therapy was not suppressed with LNMA at a dose of 100 μg/h but was significantly lowered at 300 μg/h. The efficacy of the anti–CD3 + IL–2 therapy was not diminished by LNMA administration either at 100 μg/h or at 300 μg/h.  相似文献   
23.
We report improvement in muscle strength in a patient with multifocal motor neuropathy (MMN) when given high-dose intravenous immunoglobin (i.v.-Ig) treatment. The patient had asymmetrical limb weakness, atrophy and absent or weak reflexes, but no sensory disturbances. Neurography showed multiple conduction blocks in peripheral motor nerves but no sensory nerve abnormalities. Serum and anti-GM1 antibodies were not found, however, the patient had serum antibodies against the glycolipid LK1, an epitope found both in glycolipid and also in some glycoproteins in peripheral nerve myelin. Muscle strength improved 5 days after i.v.-Ig therapy, and lasted about 10 weeks. Repeated courses of treatment resulted in similar improvement. This is, to our knowledge, the first patient reported with MMN found to have antibodies against the glycolipid LK1.  相似文献   
24.
Pierre Jallon 《Epilepsia》1997,38(S9):S37-S42
Summary: Treatment of epilepsy, one of the most common neurologic disorders, has evolved from "institutional" poly-therapy to "dogmatic" monotherapy, and, most recently, to "rational" polypharmacy. The introduction of bromides for the treatment of epilepsy was followed first by phenobarbital and then by phenytoin as therapeutic options. Although attempts to combine medications were legion, none was supported by studies that demonstrated the benefit of such combinations. The issue of adverse effects became a principal argument in favor of monotherapy. Monotherapy, using newly developed drugs, avoided problems due to drug interactions but was ineffective in 20–30% of patients. A greater understanding of basic disease mechanisms and developments in molecular biology have led to an increased number of effective drugs for the estimated 6–12% of patients with epilepsy whose condition is intractable. Clinical research continues to build on the work of basic scientists in attempting to develop treatments based on a desire to move beyond the palliative and to affect the causative mechanisms of the disease. Novel medical approaches now under exploration include the use of drugs with complementary mechanisms of action, stimulation of various components of the nervous system, biochemical manipulations, focal intracerebral drug perfusion, and gene therapy.  相似文献   
25.
Activity levels of cytokines were measured by stimulation of the cell lines NFS-60, 7TD1, and TF-1. In 39 samples of amniotic fluid, levels of Granulocyte-Stimulating Factor (G-CSF) were 1434±2063 (mean±SD) and of Interleukin (IL-6) 546±1071 pg/ml; Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) was not detectable. IL-6 was correlated to G-CSF (r=0.3; p=0.003). G-CSF (p=0.0002) and IL-6 (p=0.006) were influenced by Alpha-Fetoprotein (AFP) and G-CSF by rhesus-incompatibility (p=0.0004). These findings suggest that cytokines such as IL-6 and G-CSF play some role in physiological and pathological pregnancy.Abbreviations G-CSF granulocyte-colony stimulating factor - GM-CSF granulocyte-macrophage colony stimulating factor - M-CSF macrophage-colony stimulating factor - CSF colonystimulating factor - IL-6 interleukin-6 - IL-11 interleukin-11 - AFP alpha-fetoprotein - NFS-60 cell line - 7TD1 cell line - TF-l cell line - rh recombinant human - MTT 3-(4,5-dimethylthiazol2-yl)-2,5-diphenyl tetrazolium bromide - FCS fetal calf serum - RPMI 1640 nutrient solution - ATCC American Tissue Culture Collection Correspondence to: E. Weimann  相似文献   
26.
1. The authors investigated the effect of two extrahepatic cholestasis models (one by bile duct ligation and the other by choledocho-jugular fistula) on the hepatic clearance of horseradish peroxidase in male Sprague-Dawley rats divided into four groups. 2. In groups A (n = 5 rats) and B (n = 5), bile duct ligation was performed, while a choledocho-jugular fistula was created in groups C (n = 5) and D (n= 7). A 10 mg intravenous bolus of horseradish peroxidase was injected after 24 h (groups A and C), 48 h (groups B and D) or 1 h (Group E; five sham-operated rats). Serum and bile samples were then serially collected for 2 h. 3. In all groups, serum horseradish peroxidase levels increased soon after injection and then rapidly decreased, the curves being similar. Biliary excretion increased for 30 min and then slowly decreased. The highest horseradish peroxidase biliary concentrations and outputs were found in Group B followed by Group A; both groups had significantly higher levels than Group E. No difference was found between horseradish peroxidase biliary excretion of groups C and D and that of sham-operated rats. 4. When each group was considered separately, sampling times correlated with the corresponding ratios of bile/ plasma HRP. Significant differences were found between the relative slopes of groups A, B and E, but not between those of groups C, D and E. 5. In conclusion, bile duct obstruction greatly affects the plasma-bile transfer of fluid phase markers, such as horseradish peroxidase, while single retention, caused by choledocho-jugular fistula, has no influence. The increased biliary hyperpressure related to the duration of cholestasis may account for the degree of horseradish peroxidase transfer which, in turn, probably depends on an enhanced paracellular passage.  相似文献   
27.
Summary One hundred patients with a verified subarachnoid haemorrhage were studied in a double blind, placebo-controlled trial at a single centre to determine the value and relative risks of tranexamic acid (TXA) in the management of ruptured intracranial aneurysms. The incidence of recurrent haemorrhage between active and placebo groups was identical (12%) and the mortality from recurrent haemorrhage was 7% and 5%, respectively. The overall incidence of cerebral infarction before surgery, at discharge and at 6 months follow-up was greater in the TXA group (27%) than in the control group (11%). Post-operative cerebral ischaemia was significantly more frequent in the active, 18 of 29 as compared to 6 of 32 patients, in the placebo group. In a fifth of the patients in whom cerebral blood flow was estimated there was a significant reduction of cerebral blood flow (CBF) on the side of the ruptured aneurysm in the TXA treated group. It is suggested that this may be the cause of the increased incidence of cerebral ischaemia in this group. There was no significant difference in the incidence of cerebral vasospasm, hydrocephalus, visual disturbances and gastrointestinal disturbances.More fatalities were encountered from ischaemia and recurrent haemorrhage in the TXA group but these differences did not reach statistical significance at the 5% level. Given that disability was due to either vasospasm or recurrent haemorrhage then a patient under TXA treatment was significantly more likely to have disability due to vasospasm (p<0.04); the reverse was true for the placebo patient (p<0.05).  相似文献   
28.
A survey of 402 normal subjects (203 men, 199 women) was conducted to assist in distinguishing potential differences in norms of hand strength. Norm data had previously been collected from mixed occupational groups, but in the present study it was hypothesised that people involved in heavy manual work on a daily basis might possess greater hand strength than others. The volunteers were adults working in industry and agriculture; they were subdivided into occupational categories. Measurements of grip, key and palmar pinch using the Jamar dynamometer and B and L pinch gauge were collected, using the protocol described by Mathiowetz. Volunteers also rated their individual hand strength job requirements subjectively. Mean values were established with regard to age, sex, dominance, occupational group and subjective rating. Significant differences were found with regard to age and sex but not to dominance; there was no evidence of differences between occupational groups or between subjective rating and individual scoring, i.e. volunteers who perceived their job as requiring a high degree of strength did not achieve higher test measurements than others. A high interrater reliability was demonstrated when comparing these follow-up measurements with the original data. It was concluded that, for clinical and rehabilitative purposes, therapists can interpret assessment of outcome most accurately by comparing patients' results with the existing norm data.  相似文献   
29.
Omeprazole is a substituted benzimidazole that causes dose-dependent intracellular inhibition of gastric acid secretion in humans. This double-blind study examined the effect of omeprazole in decreasing gastric acidity and gastric residual volume in outpatient adults. Unpremedicated outpatients, ASA I-III, 18 years or older (n = 17), were randomly assigned to receive omeprazole 80 mg, or placebo by mouth the night before scheduled elective outpatient surgery. The patients were fasted for 8 h prior to surgery. After the patient was anesthetized, an orogastric tube was inserted with proper placement verified by auscultation for gastric sounds. Gastric residual contents were withdrawn into a Luken's trap, and pH was then determined and gastric volume indexed to weight (ml.kg-1). Data were analyzed by a t-test, with P less than 0.05 considered statistically significant. Patient characteristics of both groups were similar. There was a statistically significant difference between the two groups for pH (P = 0.02), but not between the two groups for gastric volume indexed to weight (P = 0.07).  相似文献   
30.
本文采用层析法进行鉴定,用氨基酸分析仪测氨基酸的含量,为胎盘组织液的质量标准提供可靠依据。本法准确率为99%。  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