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   2188篇
  免费   57篇
  国内免费   5篇
耳鼻咽喉   14篇
儿科学   62篇
妇产科学   74篇
基础医学   138篇
口腔科学   76篇
临床医学   383篇
内科学   521篇
皮肤病学   124篇
神经病学   44篇
特种医学   5篇
外科学   232篇
综合类   28篇
一般理论   21篇
预防医学   164篇
眼科学   20篇
药学   309篇
肿瘤学   35篇
  2016年   20篇
  2015年   16篇
  2014年   24篇
  2013年   43篇
  2010年   44篇
  2009年   44篇
  2001年   21篇
  1999年   39篇
  1998年   65篇
  1997年   91篇
  1996年   106篇
  1995年   82篇
  1994年   74篇
  1993年   63篇
  1992年   73篇
  1991年   75篇
  1990年   75篇
  1989年   63篇
  1988年   62篇
  1987年   49篇
  1986年   61篇
  1985年   44篇
  1984年   50篇
  1983年   43篇
  1982年   42篇
  1981年   39篇
  1980年   40篇
  1979年   38篇
  1978年   43篇
  1977年   35篇
  1976年   24篇
  1975年   21篇
  1972年   21篇
  1971年   21篇
  1969年   16篇
  1968年   24篇
  1967年   17篇
  1966年   15篇
  1965年   15篇
  1964年   16篇
  1963年   19篇
  1962年   17篇
  1961年   19篇
  1959年   30篇
  1958年   46篇
  1957年   43篇
  1956年   36篇
  1955年   39篇
  1954年   30篇
  1948年   20篇
排序方式: 共有2250条查询结果,搜索用时 15 毫秒
101.
We report our experience with nasal mask ventilation in children and adolescents with type II respiratory failure admitted to the paediatric intensive care unit (PICU) over an 18-month period. Seven patients were treated with nasal mask ventilation during part of their PICU stay. All showed significant improvement in arterial pH, PaCO2, and PaO2/FiO2 from presentation to discharge, although at discharge PaCO2 and PaO2/FiO2 fell outside of the normal range. Complications occurred in four patients. When compared to 11 patients with type II respiratory failure not treated with nasal mask ventilation, the nasal mask ventilation group had a similar PICU length of stay and incidence of complications. We conclude that nasal mask ventilation may be useful in maintaining near normal alveolar ventilation in selected children with type II respiratory failure and that a prospective study of this technique is indicated.  相似文献   
102.
Four cases of giant colonic diverticula are presented with emphasis on plain film recognition employing the "balloon sign", a persistent, rounded lucency which is consistently seen on any abdominal scout film or survey. The importance of this finding is even greater in the absence of gastrointestinal complaints in view of the complication of torsion and perforation  相似文献   
103.
1. A technic is described for the direct and indirect visualization of affinitybetween fluorescein labeled antiglobulin serum and megakaryocytes.

2. Fluorescent megakaryocytes have been found with this technic in themarrow of some patients with chronic ITP, but not in acute ITP. It was possiple to confer fluorescence on normal megakaryocytes by incubating themwith sera from patients with chronic ITP, and from a woman who had a childwith neonatal thrombocytopenia.

3. Similar reactions were noted in three patients with systemic lupuserythematosus.

4. These findings indicate adherence of a humoral substance (antibody?)for megakaryocytes, which may have etiologic significance in chronic ITP.

Submitted on August 16, 1961 Accepted on February 23, 1962  相似文献   
104.
ABSTRACT: Previous studies employing ultraviolet light-induced (UV-induced) and methylcholanthrene-induced (MCA-induced) tumors have elucidated the presence of three functionally denned groups of tumor antigens. One is the tumor-specific transplantation antigens (TSTA), which represent the most potent tumor-rejection antigens. The second is the tumor-associated transplantation antigens (TATA), which appears to be etiology-dependent (ultraviolet light-UV-or methylcholanthrene-MCA) and is capable of acting as a rejection antigen following hyperimmunization. The third is the tumor-associated antigens (TAA) which, to date, has only been defined by in vitro assays. The TAA appear to be present on all murine tumors tested. We feel that the TAA are functionally related to fetal antigens. In these experiments, cytotoxic T lymphocytes (CTL) generated from the popliteal lymph nodes of C3H mice immunized with a C3H, UV-induced tumor (RD-1024) were capable of causing specific lysis of not only the immunizing tumor but also of fetal fibroblasts (FFB) and placental cells (PC) obtained from syngeneic C3H × C3H matings. In cold-cell inhibition experiments, unlabeled placental cells could abolish specific lysis of labeled placental cell targets, fetal fibroblast targets, and secondary tumor targets (LR80, a MCA-induced tumor) while not inhibiting lysis of the immunizing tumor. Placental cells and fetal fibroblasts from 12-day to 14-day syngeneic C3H pregnancies were capable of eliciting a CTL response by footpad immunization of virgin C3H female mice. Anti-FFB or anti-PC CTL were capable of killing all tumors tested (UV-induced or MCA-induced) and were without H-2 restriction as demonstrated by specific lysis of a BALB/c tumor. These results indicate that antigenic determinants present on 12-day to 14-day fetal and placental cells satisfy the functional definition of the TAA.  相似文献   
105.
Studies on Reproduction in Rats with Meclofenamate Sodium, aNonsteroidal Anti-inflammatory Agent. PETRERE, J. A., HUMPHREY,R. R., ANDERSON, J. A., FITZGERALD, J. E., AND DE LA IGLESIA,F. A. (1985). Fundam. Appl. Toxicol. 5, 665–671. Reproductionand teratology studies were performed in rats given meclofenamatesodium, a nonsteroidal anti-inflammatory agent. Dosages of 0,3, 6, and 9 mg/kg were administered orally as dietary admixturesin the Fertility and Perinatal-Postnatal studies. In the Teratologystudy, dosages of 10, 12, 15, and 20 mg/kg were administeredby intragastric intubation. In the Male-Fertility study no adverseeffects on fertility or litter and offspring parameters wereobserved in two generations. In the Female-Fertility and Perinatal-Postnatalstudies, maternal toxicity (death associated with intestinalulceration and adhesions) was particularly evident during lactation.Prolonged gestation periods, decreased weanling weights, andincreased weanling mortality were evident at dosages of 6 and9 mg/kg. Increased postimplantation loss occurred at 6 and 9mg/kg in the Term Sacrifice subgroup of the Female-Fertilitystudy. Fertility rates were unaffected and all other litterand offspring parameters of the F1 and F2 generations appearednormal. In the Teratology study no adverse effects on embryonicor fetal development were evident at maternally toxic dosagesup to 20 mg/kg. © 1985 Society of Texicology.  相似文献   
106.
107.
Aminoglycoside-Induced Biphasic Hindlimb Paralysis in the Rat:A Histological and Electro-physiological Assessment. TOLLIVER,J. M., AND WARNICK, J. E. (1985). Fundam. Appl. Toxicol.. 5,933-947.The intrathecal injection of gentamicin into a human patientwith gram-negative bacterial meningitis as well as its intracisternalinjection into rabbits caused spongy-like lesions in the graymatter and tetraplegia in rabbits. To characterize this neurotoxiceffect, gentamicin was injected into the subarachnoid spaceof the lumbar spinal cord of the rat. A biphasic hindlimb paralysisensued which consisted at first of a transient flaccid paralysislasting 1 to 5 hr followed by a permanent flaccid paralysiswhich developed after 24 to 36 hr. The initial paralysis occurredsimultaneously with the transient loss of reflex transmissionthrough the cord but in the absence of lesions in the spinalcord or physiological alterations of neuromuscular transmissionand muscle contraction. The onset of the second phase of paralysisoccurred concomitant with changes in reflex transmission andappearance of lesions. Loss of neuromuscular transmission andappearance of signs of denervation (e.g., depolarization, alterationin action potential parameters, and chemosensitivity) appearedafter the second phase of paralysis was established Both theinitial transient and late permanent paralysis originated inthe spinal cord. The early transient paralysis appears to bedue to a central block of transmission while the late paralysisapparently resulted from neuronal damage. The neurotoxic effectsof aminoglycosides on neuronal elements in the spinal cord resultedin secondary effects (signs of denervation) in hindlimb muscles.  相似文献   
108.
109.
110.
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