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   9468篇
  免费   444篇
  国内免费   29篇
耳鼻咽喉   97篇
儿科学   153篇
妇产科学   250篇
基础医学   1295篇
口腔科学   214篇
临床医学   601篇
内科学   2056篇
皮肤病学   226篇
神经病学   804篇
特种医学   553篇
外科学   1681篇
综合类   23篇
一般理论   1篇
预防医学   249篇
眼科学   132篇
药学   583篇
中国医学   12篇
肿瘤学   1011篇
  2022年   106篇
  2021年   176篇
  2020年   103篇
  2019年   122篇
  2018年   151篇
  2017年   121篇
  2016年   130篇
  2015年   164篇
  2014年   210篇
  2013年   284篇
  2012年   441篇
  2011年   462篇
  2010年   241篇
  2009年   202篇
  2008年   408篇
  2007年   412篇
  2006年   401篇
  2005年   420篇
  2004年   384篇
  2003年   428篇
  2002年   435篇
  2001年   336篇
  2000年   394篇
  1999年   264篇
  1998年   95篇
  1997年   79篇
  1996年   85篇
  1995年   72篇
  1994年   76篇
  1993年   59篇
  1992年   221篇
  1991年   225篇
  1990年   197篇
  1989年   241篇
  1988年   204篇
  1987年   212篇
  1986年   181篇
  1985年   152篇
  1984年   97篇
  1983年   79篇
  1982年   47篇
  1979年   77篇
  1978年   67篇
  1977年   49篇
  1975年   48篇
  1974年   52篇
  1972年   58篇
  1971年   55篇
  1969年   45篇
  1968年   49篇
排序方式: 共有9941条查询结果,搜索用时 15 毫秒
61.
A case of infantile XX male syndrome with bilateral scrotal testes and penoscrotal hypospadias is presented. No evidence of XX/XY mosaicism or Y chromatin was obtained in preparations from cultures of the peripheral blood, skin fibroblast, or other tissues. Although true hermaphroditism was suspected, exploration of the bilateral gonadal structures failed to detect the presence of ovarian structures, either grossly or microscopically. Furthermore, exploratory laparotomy revealed no Mullerian structures. The difficulty of early diagnosis of XX males in infancy is emphasized.  相似文献   
62.
In mice, the mean serum concentration of the acute-phase reactant alpha1-acid glycoprotein increased 34–48% over 14 days following experimental induction of pneumonitis by intranasal inoculation of influenza A virus. Inoculation of undiluted (hemagglutination titer 640) and 10–1 dilution of virus was followed by development of maximum concentrations of alpha1-acid glycoprotein in serum at seven days, of 334g/ml, compared to a concentration in control mice inoculated with irradiated inactivated virus of 225g/ml (P=0.002). Infection with 10–2 virus yielded a peak serum alpha1-acid glycoprotein of 301g/ml at four days, 34% higher than in control mice at four days (P=0.04). There were no differences in alpha1-acid glycoprotein concentrations among virus-infected mice. Influenza A virus pneumonitis was confirmed histologically, by virus isolation, and by serologic testing, but no inoculum-dependent differences were observed. On day 7, there was a direct relationship demonstrated between the severity of pneumonitis evaluated histologically and the serum alpha1-acid glycoprotein concentration (r=0.50;P<0.02). Influenza A pneumonia in mice is associated with increased concentrations of alpha1-acid glycoprotein in serum; the increase may be directly related to the severity of the pulmonary inflammation.  相似文献   
63.
Summary The effects of pre-motion silent period (PSP) on dynamic force exertion were studied in ten healthy subjects performing ballistic elbow extensions. The experiments were designed to evaluate the significance of mean differences between the averaged dynamic force curves of two groups: PSP-presence groups and PSP-absence groups. The presence of PSP was judged quantitatively and automatically by means of a newly developed method using statistical analysis. The results indicated that there were two effects of PSP on dynamic force exertion: one was a reducing effect, observed prior to the movement; the other was a reinforcing effect, observed in the first part of the ballistic movement. The duration of the reinforcement was significantly correlated with the duration of the reducing effect of PSP. The findings suggested that the reinforcement of dynamic force may be produced by the pre-stretch of agonistic muscles caused by prior force reduction due to PSP occurrence. The fact that PSP plays an important role in dynamic force exertion suggests that PSP may be incorporated in the central motor control system designed to interrupt the background activity, to stretch the agonist and to reinforce the dynamic force.  相似文献   
64.
Twelve strains of adenovirus serotype 19, isolated from cases of epidemic keratoconjunctivitis in Japan in 1992, 1993, 1997, and 1998, were analyzed by DNA restriction analysis, using restriction endonucleases BamHI, BglI, BglII, EcoRI, HindIII, KpnI, PstI, SacI, SalI, SmaI, and XhoI. Among these 11 restriction endonucleases, EcoRI, PstI, SacI, and SmaI were discriminative enzymes, showing restriction patterns different from those reported previously for the prototype and the variant 19a. This new genome type was isolated in 1997 and 1998, when an increase of epidemic keratoconjunctivitis cases caused by adenovirus serotype 19 was observed for both sporadic and nosocomial infections. Strains from 1992 and 1993 showed restriction patterns similar to those of the worldwide reported variant 19a for all enzymes used. The changes detected in strains from 1997 and 1998 could be the reason for the recent epidemic.  相似文献   
65.
BACKGROUND: The comparative studies of the prevalence of atopic dermatitis and skin barrier functions in Japanese and Chinese were performed. METHODS: Clinical investigations were performed in 68 elementary school students in Lhasa, Tibet Autonomous Region and 67 students in Yixing, Jiangsu Province in China, and 99 students in Nishinomiya, Hyogo in Japan. Transepidermal water loss (TEWL) and capacitance were measured. Questionary survey about bathing frequency was also performed for students in Lhasa, Yixing and Osaka. RESULT: The prevalence rate of atopic dermatitis was 0% in Lhasa, 2.63% in Yixing, 4.26% in Nishinomiya. TEWL of students in Nishinomiya was higher than that in Yixing and Lhasa. Capacitance of students in Lhasa was lower than that in Nishinomiya and Yixing. The frequency of taking a bath in Lhasa was about 2.2 times per month and fewer than that in Nishinomiya and Yixing. CONCLUSION: There was tendency that the prevalence of atopic dermatitis increased according to increase of TEWL. It was thought that more investigations are necessary whether the development of habitat and environment influence the prevalence of atopic dermatitis and skin barrier function.  相似文献   
66.
We report the clinical course and biochemical findings of a 10-year-old, mentally retarded girl with late-onset holocarboxylase synthetase (HCS, gene symbol HLCS) deficiency and only partial response to biotin. On treatment, even with an unusually high dose of 200mg/day, activities of the biotin-dependent mitochondrial carboxylases in lymphocytes remained below 50% of the mean control values. Not only urinary 3-hydroxyisovaleric acid excretion has been persistently elevated, but also plasma and, with even higher concentrations, cerebrospinal fluid 3-hydroxyisovaleric acid have not normalized. The unusual and insufficient response of this patient to biotin treatment can be explained by the effect of the combination of the common HLCS allele IVS10 +5 g>a on one chromosome and a truncating mutation on the other. This case illustrates mechanisms involved in the genotype-phenotype correlation that unequivocally exists in HCS deficiency.  相似文献   
67.
T Aoki 《Arerugī》1992,41(9):1349-1353
  相似文献   
68.
A primary tumor of the middle ear was examined histologically, histochemi-cally, immunohistochemically and ultrastructurally. Neuroendocrine cell differentiation, a carcinoid feature, was demonstrated by the presence of numerous argyrophil granules, as well as positive serotonin, glicentin, glucagon, and human pancreatic polypeptide (hPP) granules in some of the Grimelium-positive cells. Chromogranin A was also detected in the cells, but much less frequently than Grimelius-positive staining. Neither neuron-specific enolase (NSE) nor epithelial membrane antigen (EMA) was demonstrated in the tumor. Mucin was demonstrated only intraluminally. Electron microscopy revealed many typical neurosecretory granules in tumor cells, but no apical mucin granules. The tumor appeared to be benign, and there has been no sign of recurrence during a postoperative period of one year. ACTA PATHOL JPN38: 1453–1460, 1988.  相似文献   
69.
N Aoki  Y Ohno 《Immunology》1987,60(1):51-55
The requirements for a primary, antigen-specific in vitro immunization of human peripheral lymphocytes using haemocyanin, a T-cell dependent antigen, have been studied. In order to obtain a specific response in vitro the peripheral lymphocytes had to be separated into B, T, accessory (A) and dendritic (D) cells. These cells were activated and reconstituted to give a population with a B:T ratio of 1:2. If the induction was supported by MHC-restricted, radioresistant T cells, this cell population could then be antigen-specifically activated using haemocyanin. The immunization had also to be supported by cytokines, such as B-cell growth and differentiation factors, interleukin-2 and gamma-interferon. A 5-day in vitro immunization using 2 micrograms haemocyanin/ml resulted in 200-300 cells secreting anti-haemocyanin-specific antibodies per 10(6) B cells.  相似文献   
70.
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