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   921609篇
  免费   63805篇
  国内免费   2486篇
耳鼻咽喉   12754篇
儿科学   29351篇
妇产科学   26810篇
基础医学   128793篇
口腔科学   25359篇
临床医学   76626篇
内科学   187934篇
皮肤病学   19459篇
神经病学   72394篇
特种医学   37163篇
外国民族医学   345篇
外科学   146104篇
综合类   19667篇
现状与发展   1篇
一般理论   268篇
预防医学   66100篇
眼科学   20756篇
药学   65618篇
中国医学   1930篇
肿瘤学   50468篇
  2019年   7250篇
  2018年   10210篇
  2017年   7852篇
  2016年   8395篇
  2015年   9504篇
  2014年   13358篇
  2013年   20416篇
  2012年   27319篇
  2011年   28982篇
  2010年   17460篇
  2009年   16512篇
  2008年   27178篇
  2007年   28890篇
  2006年   28924篇
  2005年   28320篇
  2004年   27107篇
  2003年   26163篇
  2002年   25666篇
  2001年   41617篇
  2000年   42791篇
  1999年   36505篇
  1998年   10107篇
  1997年   9254篇
  1996年   9173篇
  1995年   8531篇
  1994年   8145篇
  1993年   7634篇
  1992年   28307篇
  1991年   27081篇
  1990年   26497篇
  1989年   25430篇
  1988年   23640篇
  1987年   23251篇
  1986年   22338篇
  1985年   21226篇
  1984年   15865篇
  1983年   13560篇
  1982年   8119篇
  1979年   14660篇
  1978年   10246篇
  1977年   8676篇
  1976年   8180篇
  1975年   9001篇
  1974年   10732篇
  1973年   10207篇
  1972年   9680篇
  1971年   8937篇
  1970年   8596篇
  1969年   8040篇
  1968年   7694篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Summary Stress-induced hyperthermia (SIH), which is seen in the last mice removed from the cage, is a novel animal model sensitive to anxiolytic drugs. SIH is antagonized by CL 218872 (25 and 50 mg/kg, os), by tracazolate (5 and 7.5 mg/kg, ip) and by 2-AP-5 (50 and 100 mg/kg, ip). At higher dose, CL 218872 (100 mg/kg, os) and tracazolate (12.5 mg/kg, ip) lose their activity.PK 9084 (5–40 mg/kg, ip) and CGS 9896 (2–20 mg/kg, both ip and os) were also ineffective in preventing SIH. The anti-hyperthermic effect of CL 218872 (25 mg/kg) and tracazolate (7.5 mg/kg) was blocked by the benzodiazepine antagonist Ro 15–1788 (15 mg/kg). CGS 9896 (10 mg/kg, os) also reversed the effect of CL 218872 (25 mg/kg) on SIH.Differently from anxiolytics, MK-801 (0.5–1 mg/kg, os), PCP (2.5 mg/kg, ip) and d-amphetamine (10 mg/kg, ip) evoked hyperthermia in the first set of mice and prevented a further stress-induced rise of body temperature in the last set of mice.  相似文献   
992.
A modified method for measuring vitamin E is described, making use of thin-layer chromatography with Silufol plates. Effects of various storage conditions of the blood serum on its vitamin E levels were examined. Vitamin E proved to be sufficiently stable at storage at -10 degrees C and defrosting under 20 degrees C. Comparison of this mode of storage with other ones has demonstrated its advantages. The method was tried in clinical practice in examinations of patients with pulmonary tuberculosis, chronic alcoholism, females suffering from infertility due to inflammations and healthy ones (controls) and found to be accurate, reproducible, and informative.  相似文献   
993.
Analytic, within-subject, and between-subject biologic variations were estimated for leukocytes, erythrocytes, hemoglobin, hematocrit, mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin content (MCHC), platelets, and a three-component differential count (lymphocytes, monocytes, and granulocytes in terms of both concentration and percentage of leukocytes) in cohorts of 12 male and 12 female healthy elderly subjects. The assays were performed with an Ortho ELT-800 automated analyzer. The estimates of within-subject biologic variation were similar to published data on young subjects, indicating that this aspect of homeostasis is not compromised in the elderly. The data were used to derive objective analytic goals; goals were surpassed except for assays of erythrocytes, hematocrit, and the derived MCV, MCH, and MCHC. The changes required for serial results to be significantly different were determined and found to be generally valid because most quantities have no heterogeneity of within-subject variation. All quantities had significant individuality; in consequence, conventional population-based reference values are of limited utility, and screening using reference limits will not detect latent or early disease in many subjects.  相似文献   
994.
995.
The study concerns symptoms and behavioral characteristics induced by MPTP in a 20-year-old Macaca cynomolgus fascicularis, their evolution over 7 months, and the animal's response to 1-dopa treatment. The symptoms which the animal developed include those that have been described earlier in Macaca mulatta and Saimiri sciureus, i.e., rigidity, action tremor, postural tremor, postural flexion, hypokinesia, and bradykinesia. In addition, however, the animal developed a 3.8 Hz resting tremor which in humans is pathognomonic of Parkinson's disease, as well as cogwheeling, the glabellar tap sign, drooling, impaired ability to relax, and many other symptoms. Also unlike previously described MPTP monkeys, the animal's symptoms neither improved spontaneously, nor did they remain stable shortly after MPTP injection. Instead, symptoms steadily progressed to reach a severe status 2 months after MPTP, and further progression was apparent after another 5 months. Therapeutic responses to 1-dopa required accumulation of or kindling by the 100 mg unit doses that were spaced 4 hr apart, were often organized in time as ON episodes that alternated with OFF episodes, and were associated with dyskinesias and bizarre behavior. Of particular interest is that the animal showed kinesia paradoxa which, in humans, constitutes a feature that is unique to Parkinson's disease among the extrapyramidal disorders. In addition to available evidence, the present findings validate the syndrome induced by MPTP in monkey as an animal analogue of Parkinson's disease. Taxonomic category, age, and the occurrence of shock in response to MPTP are discussed as variables that may possibly co-determine the pathology which MPTP may induce in monkey.  相似文献   
996.
997.
998.
999.
1000.
Regulation of cell-mediated immunity in cutaneous leishmaniasis   总被引:1,自引:0,他引:1  
F Y Liew 《Immunology letters》1987,16(3-4):321-327
There is now good evidence that cell-mediated immunity (CMI) rather than humoral antibody plays a causal role in acquired immunity to leishmaniasis. In genetically susceptible strains of mice, the failure to control the disease progression is associated with a population of Lyt-2-T cells which can prevent the induction or expression of curative CMI and hence exacerbate disease development. Susceptible BALB/c mice can be rendered resistant to L. major infection by prior sublethal dose gamma-irradiation, anti-mu antibody treatment from birth, anti-L3T4 antibody treatment or intravenous (i.v.) or intraperitoneal (i.p.) route of immunisation with killed L. major promastigotes or isolated leishmanial antigens. The route of immunisation, however, appears crucial in the induction of prophylactic immunity. Subcutaneous (s.c.) and intramuscular routes of immunisation with killed promastigotes are not only ineffective, they induce a population of Lyt-2- L3T4+ T cells which inhibit the prophylactic effect of i.v. immunisation. Although both the disease-promoting T cells and the host-protective T cells express the same phenotypic cell surface markers, they differ functionally. Protective T cells produce interferon-gamma (IFN-gamma) and macrophage-activating factor (MAF) when cultured in vitro with leishmanial antigens, whereas the disease-promoting T cells do not. In addition, these latter cells are able to produce substances in their antigen-specific culture supernatant which inhibits the MAF activity of the host protective T cells.(ABSTRACT TRUNCATED AT 250 WORDS)  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