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   697065篇
  免费   33896篇
  国内免费   812篇
耳鼻咽喉   9692篇
儿科学   23161篇
妇产科学   16869篇
基础医学   116347篇
口腔科学   17085篇
临床医学   60955篇
内科学   125531篇
皮肤病学   16411篇
神经病学   49367篇
特种医学   28348篇
外国民族医学   77篇
外科学   105647篇
综合类   8685篇
现状与发展   2篇
一般理论   143篇
预防医学   46439篇
眼科学   16415篇
药学   52977篇
  1篇
中国医学   1460篇
肿瘤学   36161篇
  2021年   5114篇
  2019年   5154篇
  2018年   8466篇
  2017年   6391篇
  2016年   8070篇
  2015年   8909篇
  2014年   10850篇
  2013年   15750篇
  2012年   23659篇
  2011年   24942篇
  2010年   14451篇
  2009年   12441篇
  2008年   23239篇
  2007年   25772篇
  2006年   25319篇
  2005年   25059篇
  2004年   24231篇
  2003年   23539篇
  2002年   22952篇
  2001年   28342篇
  2000年   28909篇
  1999年   24088篇
  1998年   6797篇
  1997年   5649篇
  1996年   5376篇
  1995年   4924篇
  1992年   16704篇
  1991年   18076篇
  1990年   18132篇
  1989年   17675篇
  1988年   16099篇
  1987年   16005篇
  1986年   14856篇
  1985年   14317篇
  1984年   10669篇
  1983年   8986篇
  1982年   4864篇
  1979年   10311篇
  1978年   7403篇
  1977年   5998篇
  1976年   6253篇
  1975年   7675篇
  1974年   8541篇
  1973年   8177篇
  1972年   7637篇
  1971年   7300篇
  1970年   6760篇
  1969年   6303篇
  1968年   5976篇
  1967年   5373篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
Synthesis of Estradiol Haptens Two estradiol haptens, 4-(3β,17β-dihydroxyestran-7α-yl)butanoic acid ( 9 ) and 7α-(4-aminobutyl)-3β,17β-estradiols ( 13 ), were prepared from 19-nortestosterone by partial synthesis. The binding activity for the cytosol estrogen receptor was determined by competition against [3H]-estradiol; at a concentration of 2×10?7mol/l, compound 9 displaces 50% of [3H]-estradiol. Attached to AH-Sepharose 4B compound 9 allows the cytosol estrogen receptor from calf uterus to be concentrated 1800-fold by affinity chromatography.  相似文献   
102.
103.
The effect of proteases inhibitors, epsilon-amino-caproic acid and gordox, on reproduction of rotavirus SA-11 in MA-104 cells was studied by enzyme immunoassay. These inhibitors were shown to exert an inhibiting effect on rotavirus reproduction.  相似文献   
104.
Trends in analgesic self-poisoning in West-Fife, 1971-1985   总被引:1,自引:0,他引:1  
All admissions for analgesic self-poisoning to a district poisons unit over a 15-year period have been reviewed. During this time overdose with analgesic drugs increased to represent almost half of all admissions for self-poisoning. The types of analgesics taken in overdose also changed significantly during the period of this review. Aspirin and Distalgesic poisoning declined in incidence and more cases of self-poisoning by paracetamol and non-steroidal anti-inflammatory agents were seen. The impact of these changes on the medical management and outcome of deliberate self-poisoning is analysed. The reasons behind the trends described in this paper are assessed and their implications for future prevention and treatment are discussed.  相似文献   
105.
106.
Biopsies from the diseased bones of patients with familial expansile osteolysis (FEO) were examined by light and electron microscopy. Focal concentrations of multinuclear osteoclasts were present, and these contained viral-like microcylindrical inclusions which appeared exclusive to their nuclei. No consistent relationship was found between osteoclast size and the number of osteoclast nuclei containing microcylindrical inclusions. Quantitative histomorphometry showed evidence of increased bone remodelling with high bone cell densities and a decrease of the reversal period in bone remodelling. The lesions contained prominent woven bone and fibrovascular tissue, together with mononuclear cells and adipocytes. Little bone was found in the most radiolucent lesions, which were almost totally occupied by adipocytes and fibrovascular tissue. Serology did not reveal any significant differences between the viral antibody titres of patients and their age- and sex-matched controls. The present study suggests that intranuclear viral-like microcylindrical inclusions of osteoclasts are not a specific feature of Paget's disease, and are found in other disorders of osteoclast function, including pycnodysostosis, osteopetrosis, giant cell tumours, and familial expansile osteolysis.  相似文献   
107.
108.
The connective tissue of the knee is frequently injured by athletes, especially those involved in contact sports. It would be important in the prevention of injury as well as the strategy of physical fitness training to know whether the connective tissue is modified in response to athletic stress or training. The potential modification investigated was variability in the concentration of hydroxyproline, a post-translationally modified imino acid found principally in collagen protein. A correlation was sought between this variability and the leg strength parameters torque (expressed as ft-lbs), torque/body weight and work (expressed as ft-lbs). In a preliminary study of five subjects, no correlation was found between hydroxyproline concentration of the patellar tendon and any of the leg strength parameters. These results suggest that this modification of the collagen in connective tissue does not occur in response to athletic stress or training, but rather, for the small number of subjects investigated, appeared to be relatively constant across a range of leg strengths.  相似文献   
109.
This study was undertaken to assess the role of the hypothalamus and medulla oblongata in regulation of liver circulation in anesthetized dogs. Blood pressure, flow in hepatic artery and portal vein, and shifts of blood volume in the liver were recorded. Stimulation of the anterior hypothalamus produced changes in arterial pressure which were followed by passive changes in hepatic arterial blood flow; changes in hepatic artery resistance were rather small. Stimulation of the medial and posterior hypothalamus increased hepatic arterial resistance by 65-170%. Liver portal blood flow during stimulation of most of the hypothalamic sites decreased, hepatic portal pressure rose and vascular portal venous resistance increased 2.5-3 times. Three areas only (sympatho-inhibitory area, paraventricular and lateral hypothalamic nuclei) when stimulated produced dilatation of hepatic portal and splanchnic vascular beds, thus increasing portal blood flow. All cases of stimulation led to the decrease of blood volume in the liver by 10-36%. Stimulation of medullary structures (n. tractus solitarii, reticular nn.) caused similar changes in hepatic circulation, however the amplitude of reaction was 1.5-6 times smaller than upon hypothalamic stimulation. Central impulses to the hepatic vessels are transmitted by sympathetic adrenergic nerve fibers through vascular alpha-adrenoreceptors. It is concluded that the hypothalamic level of the central nervous system, unlike the bulbar one, exerts considerable, differentiated, well coordinated and to some extent specific influences on hepatic circulation.  相似文献   
110.
V DeBack 《Nursing outlook》1991,39(3):124-127
On May 1, 1991, the National Commission on Nursing Implementation Project officially concluded. Its legacy is one of interdisciplinary collaboration and continuing work to redesign nursing education, practice, and research systems.  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