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   21624篇
  免费   1611篇
  国内免费   63篇
耳鼻咽喉   330篇
儿科学   1137篇
妇产科学   654篇
基础医学   1784篇
口腔科学   365篇
临床医学   2623篇
内科学   4962篇
皮肤病学   339篇
神经病学   1071篇
特种医学   768篇
外科学   3719篇
综合类   475篇
一般理论   3篇
预防医学   1188篇
眼科学   887篇
药学   1556篇
  1篇
中国医学   71篇
肿瘤学   1365篇
  2023年   200篇
  2022年   276篇
  2021年   782篇
  2020年   429篇
  2019年   613篇
  2018年   785篇
  2017年   587篇
  2016年   594篇
  2015年   595篇
  2014年   872篇
  2013年   1078篇
  2012年   1517篇
  2011年   1383篇
  2010年   904篇
  2009年   744篇
  2008年   1040篇
  2007年   1053篇
  2006年   975篇
  2005年   905篇
  2004年   810篇
  2003年   689篇
  2002年   612篇
  2001年   510篇
  2000年   528篇
  1999年   440篇
  1998年   201篇
  1997年   201篇
  1996年   170篇
  1995年   167篇
  1994年   143篇
  1993年   113篇
  1992年   306篇
  1991年   269篇
  1990年   247篇
  1989年   230篇
  1988年   186篇
  1987年   190篇
  1986年   165篇
  1985年   177篇
  1984年   157篇
  1983年   149篇
  1982年   74篇
  1981年   85篇
  1979年   123篇
  1978年   90篇
  1977年   69篇
  1974年   78篇
  1973年   111篇
  1972年   101篇
  1971年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
Drug use and HIV infection may affect sex hormone levels in women. One hundred and ninety-six women with and without a history of illicit drug use (50 HIV-negative and 148 HIV-infected), with regular menses, who never used antiretrovirals, were evaluated. Luteinizing hormone levels were significantly higher in women with a CD4 cell count <200/microl (p < 0.002). Current methadone use was associated with lower levels of total testosterone (p = 0.03) and higher levels of prolactin (p = 0.002); mean estradiol levels were 43% lower in women who used intravenous drugs (p < 0.001). Alcohol and crack cocaine use was not associated with sex hormone levels. Age, race, body mass index and degree of HIV immunosuppression were also associated with differences in sex hormone levels.  相似文献   
54.
A 44-year-old man with right-sided herpes zoster ophthalmicus (HZO) developed ipsilateral third and sixth cranial nerve palsies and first-division trigeminal (fifth cranial nerve) sensory loss. MRI revealed contrast enhancement of the cisternal and cavernous portions of the third cranial nerve and high signal on a FLAIR sequence within the ipsilateral medulla at the presumed location of the trigeminal nucleus and tract. To our knowledge, this is the first report of the combination of these imaging findings in HZO.  相似文献   
55.
56.
Endothelium lines all blood vessels and the cardiac cavities and has a central role in cardiovascular homeostasis. It releases several potent substances which mediate the control of vascular tone and cardiac contraction. Endothelial dysfunction is implicated in many disease states. Elucidation of the underlying mechanisms is likely to lead to novel therapeutic strategies.  相似文献   
57.
58.
This study was conducted to determine the occurrence of menstrual-linked asthma (MLA) in India in 100 consecutive female asthmatics in the reproductive age group. The patients were required to respond to a questionnaire concerning the relationship between their asthma and the menstrual cycle. Twenty-three patients had subjective perception of deterioration in symptoms of asthma in relation to the menstrual cycle. Ten patients from both groups were also required to maintain a daily peak expiratory flow rate (PEFR) diary for 2 consecutive menstrual cycles. The mean total duration of illness in patients with MLA was significantly longer than in patients without cyclic exacerbation. Cough and breathlessness were also significantly more severe as was the disease. This was evidenced by the more frequent emergency room visits and hospitalizations in these patients. Menstrual-linked worsening of asthma was most common in the premenstrual week (17 patients). In 8 of these 17 patients, this phenomenon continued to occur during the menstrual week also. Interestingly, 1 patient complained of deterioration of asthma 2 days after menstruation was over. Such an observation is yet to be recorded. Fourteen patients reported an increase in symptoms with almost every cycle while 3 had worsening related to specific season only. Sixteen patients often required extra medication during the premenstrual and/or menstrual weeks. A significant association was also observed between severity of premenstrual syndrome and MLA. The mean PEFR values over 2 cycles revealed a significant fall in the morning as well as evening values in the premenstrual and menstrual weeks as compared to the midcycle week in patients with MLA. This fall was maximal in the premenstrual week. Such a fall was not observed in asthmatics without menstrual exacerbation of symptoms. MLA was detected in about a fourth of the female asthmatics in India and it appears to represent a more severe form of the disease. This study also documented that MLA was associated with an increase in airway resistance and was not simply due to an increased perception of symptoms during the premenstrual or menstrual weeks.  相似文献   
59.
The key informant technique   总被引:3,自引:1,他引:2  
Marshall  MN 《Family practice》1996,13(1):92-97
BACKGROUND AND OBJECTIVE: This article considers the role of the key informant techniqueas a qualitative research method and examines the potentialcontribution of the approach to health care research. METHOD: The principles underlying the technique and the advantages anddisadvantages are considered, illustrated with examples froma range of social science studies. RESULTS AND CONCLUSION: An example of the author's own use of key informants in a studyof the professional relationship between general practitionersand specialists is described. Keywords. Key informants, qualitative methods, professional relationships.  相似文献   
60.
To ascertain the potential role of reactive oxygen metabolites in the pathophysiology of obstructive uropathy, we examined the effect of probucol, an antioxidant agent, on renal function in normal rats and rats with unilateral release of bilateral ureteral obstruction (BUO) of 24 hours duration. Rats were fed either a standard diet or a standard diet containing one percent probucol for two weeks prior to study. Probucol lowered serum cholesterol in both normal and BUO rats. Probucol did not significantly affect renal function in normal rats. BUO rats given probucol had greater inulin and PAH clearances at three to five hours and three days following release of BUO than rats with BUO not given probucol. Kidneys from obstructed rats had higher levels of malondialdehyde, an index of lipid peroxidation, a greater number of leukocytes in the cortex, decreased levels of reduced glutathione and increased levels of oxidized glutathione. Renal cortex from obstructed rats treated with probucol had significantly higher levels of reduced glutathione than kidneys of obstructed rats not given probucol. A decrease in cholesterol, using another lipid-lowering agent, lovastatin, did not modify renal function in rats with BUO. The data can be interpreted to indicate a role for reactive oxygen species in the pathophysiology of obstructive nephropathy. The improved renal function seen in probucol-treated rats with BUO may be due to an effect of this agent in affecting accumulation of reactive oxygen metabolites and/or decreasing the number of leukocytes infiltrating the renal cortex.  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