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   2372篇
  免费   121篇
  国内免费   10篇
耳鼻咽喉   24篇
儿科学   93篇
妇产科学   60篇
基础医学   310篇
口腔科学   14篇
临床医学   177篇
内科学   326篇
皮肤病学   72篇
神经病学   95篇
特种医学   63篇
外科学   343篇
综合类   212篇
预防医学   141篇
眼科学   131篇
药学   204篇
中国医学   53篇
肿瘤学   185篇
  2023年   11篇
  2022年   29篇
  2021年   68篇
  2020年   27篇
  2019年   37篇
  2018年   56篇
  2017年   48篇
  2016年   65篇
  2015年   60篇
  2014年   79篇
  2013年   93篇
  2012年   176篇
  2011年   135篇
  2010年   109篇
  2009年   67篇
  2008年   130篇
  2007年   116篇
  2006年   106篇
  2005年   96篇
  2004年   109篇
  2003年   78篇
  2002年   69篇
  2001年   72篇
  2000年   77篇
  1999年   60篇
  1998年   38篇
  1997年   42篇
  1996年   33篇
  1995年   18篇
  1994年   19篇
  1993年   18篇
  1992年   25篇
  1991年   40篇
  1990年   36篇
  1989年   32篇
  1988年   30篇
  1987年   20篇
  1986年   14篇
  1985年   23篇
  1984年   14篇
  1983年   18篇
  1982年   11篇
  1981年   9篇
  1980年   8篇
  1979年   17篇
  1978年   10篇
  1976年   7篇
  1975年   8篇
  1974年   6篇
  1969年   7篇
排序方式: 共有2503条查询结果,搜索用时 15 毫秒
21.
A 71 year-old woman with a large tumor of the upper lobe of the left lung was diagnosed as having metastatic adrenal cortical carcinoma nine years after the initial adrenalo-nephrectomy. The patient was well with no recurrence for six years following resection of the single lung metastasis.  相似文献   
22.
In an age-adjusted comparison with white men, black men have a significantly higher increase in esophageal and other types of cancer associated with environmental causes. The basis of this increase in cancer rates in blacks over the last two decades is unknown. Since cancer patients generally show an impairment in cell-mediated immune (CMI) functions, we measured certain CMI reactions in cultured lymphocytes derived from black healthy subjects and cancer patients. We also determined the levels of aryl hydrocarbon hydroxylase (AHH) induced in these lymphocytes. AHH catalyzes the activation of polycyclic aromatic hydrocarbons (PAH) to intermediates which might alter CMI functions.  相似文献   
23.
The authors report two rare cases of 'non-syndromic spontaneous keloids' occuring in siblings. This represents another unexplored area in the field of 'keloid challenge', warranting further research and development.  相似文献   
24.
S Maiti  B Das  N C Mandal 《Virology》1991,182(1):351-352
Both spontaneous and NTG-induced mutants of Escherichia coli 594 insensitive to the lethal action of lambda P gene were isolated and called rpl (resistant to P lethality). These mutants were of two types, showing different phenotypes. On type I rpl mutants, lambda cl- and lambda v1v3 did not plate, while lambda vir, lambda cl- c17, lambda imm434, and lambda imm21 did; plasmid pMR45 carrying the lambda P gene could not complement lambda imm21P- phage in type I mutants. On the other hand, the type II rpl mutants support the growth of all the above phages including lambda cl-. Neither type of rpl mutation affects growth of the bacteria.  相似文献   
25.
Antibodies to myoglobin were immobilized by covalent linkage to polyester film for use in a solid-phase ELISA. The covalent linkage of antibody to this new solid phase was accomplished by partial acid hydrolysis of the film followed by periodate oxidation. About 60 ng of protein could be immobilized per cm2 of film and the binding was stable. Antimyoglobin IgM immobilized on the films was used in the ELISA technique to detect myoglobin within the range 0.25-10 ng. The assay procedure was found to be very accurate and the coefficient of variation of each concentration ranged from 0.63 to 2.1%. Furthermore the immobilized film could be re-used after dissociating the antigen antibody complexes.  相似文献   
26.
27.
The ability of the Vitek Yeast Biochemical Card to identify yeast isolates was compared with conventional methods. Of the fifty yeast isolates tested same species identification was obtained in thirty-four isolates. The Vitek yeast biochemical card identified 13 isolates which could not be identified by the conventional tests. Though the Vitek Yeast biochemical card gave a good rapid identification the high cost of each test severely limits its routine use in most of the laboratories.  相似文献   
28.
This paper describes the problems and solutions in using 18 MeV linear accelerator, with minimum 6 MeV electron capability, for total skin irradiation for mycosis fungoides. The 6 MeV electron energy can be degraded to acceptable electron energy of 3.2 MeV by interposing a plexiglass sheet of 9.6 mm in the beam. To minimize the bremsstrahlung, the degrading plexiglass should be kept away from the machine head. A wide area with uniform dose distribution over single plane can be achieved by using dual fields but homogenous dose distribution over irregular body surface cannot be achieved mainly because of self-shielding. The nails and the ocular lens can be easily shielded from the low energy electrons with 1.5 mm lead shield.  相似文献   
29.
AIMS--To determine whether the routine measurement of lymphocyte transformation responses to mitogenic stimuli provide any information additional to that available from routine T cell CD4 and CD8 analysis in patients with HIV infection. METHODS--The case records of 197 immunologically investigated HIV seropositive patients were reviewed. The influence of disease stage on T lymphocyte subsets and lymphocyte transformation responses (LyTR) to phytohaemagglutinin (PHA) and Pokeweed mitogen was assessed. RESULTS--The median CD3 and CD4 counts and LyTR to PHA and Pokeweed mitogen were highest in patients with persistent generalised lymphadenopathy (PGL) and decreased progressively in the order: asymptomatic patients, those with ARC, those with AIDS. LyTR to PHA was preserved in over 70% of all patients, but the response to Pokeweed mitogen was depressed in 8% of patients with PGL, 34% of asymptomatic patients, 68% of those with ARC and 78% of those with AIDS. Subnormal values of both CD4 + T cells and LyTR to Pokeweed mitogen were more common in patients with ARC and AIDS (68%) than in those who were asymptomatic or had PGL (20%). CONCLUSIONS--CD4 T cell analysis and LyTR to Pokeweed mitogen, but not to PHA, both correlate with disease states in patients with HIV infection.  相似文献   
30.
A rare case of viral encephalitis in an 18 year old recruit who presented with signs of catatonic schizophrenia is reported.KEY WORDS: Viral encephalitis, Catatonic schizophrenia  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