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   9745篇
  免费   553篇
  国内免费   102篇
耳鼻咽喉   82篇
儿科学   407篇
妇产科学   154篇
基础医学   1327篇
口腔科学   278篇
临床医学   931篇
内科学   2279篇
皮肤病学   191篇
神经病学   707篇
特种医学   691篇
外国民族医学   3篇
外科学   1546篇
综合类   111篇
一般理论   1篇
预防医学   645篇
眼科学   113篇
药学   468篇
  2篇
中国医学   6篇
肿瘤学   458篇
  2022年   58篇
  2021年   125篇
  2020年   102篇
  2019年   111篇
  2018年   173篇
  2017年   158篇
  2016年   122篇
  2015年   176篇
  2014年   215篇
  2013年   294篇
  2012年   349篇
  2011年   404篇
  2010年   281篇
  2009年   263篇
  2008年   346篇
  2007年   460篇
  2006年   371篇
  2005年   371篇
  2004年   334篇
  2003年   321篇
  2002年   309篇
  2001年   321篇
  2000年   279篇
  1999年   268篇
  1998年   221篇
  1997年   255篇
  1996年   204篇
  1995年   166篇
  1994年   157篇
  1993年   144篇
  1992年   162篇
  1991年   161篇
  1990年   180篇
  1989年   204篇
  1988年   167篇
  1987年   174篇
  1986年   172篇
  1985年   179篇
  1984年   138篇
  1983年   105篇
  1982年   64篇
  1981年   62篇
  1980年   77篇
  1979年   97篇
  1978年   70篇
  1977年   71篇
  1976年   55篇
  1975年   62篇
  1974年   63篇
  1972年   63篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Atopy — a T helper 2 cell driven hypersensitivity to innocuous antigens (allergens) which causes most cases of asthma — is of complex genetic and environmental origins. There is compelling epidemiological evidence for a rise in atopic disease in ‘westernised’ communities. The changing pattern of microbial exposure in early childhood is suggested to be the principal candidate mechanism for this rise.  相似文献   
92.
93.
BACKGROUND: The initial rate of plasma HIV-1 RNA (pVL) decline has been proposed as a marker of early efficacy of antiretroviral therapy (ART) and a possible predictor of late efficacy. We compared the rate of pVL decline in patients starting ART with nevirapine (NVP), efavirenz (EFV), or both drugs combined in addition to lamivudine (3TC) and stavudine (d4T). METHODS: Analysis of the viral decay constant (VDc) during the first 2 weeks of treatment in patients enrolled in the 2NN study who remained on allocated treatment. RESULTS: The median VDc (log10 copies per day, [interquartile range]) was similar for NVP (0.30 [0.25-0.36], EFV (0.31 [0.27-0.37]), and NVP + EFV (0.30 [0.27-0.36]). Patients with a baseline pVL >100,000 copies/mL were 8.7 (95% confidence interval [CI]: 6.2-12.3) times more likely to have a VDc >75th percentile. A high VDc was not associated with plasma drug concentration or with a decreased risk of virologic failure at week 48 after the start of therapy (hazard ratio = 0.8, 95% CI: 0.6-1.2). CONCLUSION: NVP, EFV, or NVP + EFV in combination with 3TC and d4T show similar rates of pVL decline during the first 2 weeks of treatment. The VDc with these regimens is not predictive of late virologic efficacy.  相似文献   
94.
Another synovial sarcoma with t(X;18)   总被引:3,自引:0,他引:3  
  相似文献   
95.
96.
97.
98.

Background  

The purpose of the present investigation was to determine if the salivary counts of 40 common oral bacteria in subjects with an oral squamous cell carcinoma (OSCC) lesion would differ from those found in cancer-free (OSCC-free) controls.  相似文献   
99.
We have determined cutaneous DTH reactions to SK-SD and PPD and peripheral blood lymphocyte profiles in a group of asbestos workers in two consecutive surveys. It was found that asbestosis and, to a lesser extent, the presence of ANA are significantly correlated with the lack of response to the above antigens. 83% of asbestos workers when tested at a 4 year interval fell into the same two categories of responsiveness (lack of response or response at least to one antigen).The asbestosis cases had lower total lymphocyte count as well as proportions and absolute number of E-RFC as compared to asbestos workers without asbestosis and/or ANA. Furthermore, the latter group showed the lower percentages and absolute number of E-RFC than the matched controls. The presence of ANA is also correlated with lower proportions of E-RFC. However, this is related at least in part to asbestosis.  相似文献   
100.
Angiotensin I converting enzyme (ACE, CD143) is an endothelial transmembrane Zn2+-dipeptidylpeptidase. By formation of angiotensin II and degrading bradykinin it acts as a vasoconstrictor. We examined endothelial ACE expression in human pulmonary vessels in specimens from 20 female and 19 male patients (age: 34-76 years) by immunohistochemistry. In all specimens, capillary endothelial cells showed the strongest expression, followed by those in arterioles and arteries. Venules and veins showed next to no staining. The differences in staining intensities were significant ( P<0.001). Sex affected neither the expression intensity nor the expression pattern. Summarizing, we demonstrate the existence of a vessel-type specific ACE expression pattern for pulmonary vessels. The nearly exclusive endothelial ACE expression in capillaries and arterial vessels points to ACE as an immunohistochemical marker for these vessels in normal lung tissue.  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