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   48133篇
  免费   3487篇
  国内免费   198篇
耳鼻咽喉   590篇
儿科学   1014篇
妇产科学   1001篇
基础医学   6666篇
口腔科学   1035篇
临床医学   4736篇
内科学   10045篇
皮肤病学   1079篇
神经病学   4587篇
特种医学   1968篇
外国民族医学   2篇
外科学   8665篇
综合类   485篇
一般理论   77篇
预防医学   2770篇
眼科学   940篇
药学   2816篇
中国医学   75篇
肿瘤学   3267篇
  2023年   468篇
  2022年   920篇
  2021年   1725篇
  2020年   1024篇
  2019年   1355篇
  2018年   1527篇
  2017年   1037篇
  2016年   1201篇
  2015年   1392篇
  2014年   1884篇
  2013年   2201篇
  2012年   3585篇
  2011年   3538篇
  2010年   1960篇
  2009年   1741篇
  2008年   2776篇
  2007年   2817篇
  2006年   2617篇
  2005年   2439篇
  2004年   2262篇
  2003年   2063篇
  2002年   1888篇
  2001年   529篇
  2000年   520篇
  1999年   540篇
  1998年   432篇
  1997年   345篇
  1996年   253篇
  1995年   249篇
  1994年   209篇
  1993年   213篇
  1992年   366篇
  1991年   338篇
  1990年   313篇
  1989年   274篇
  1988年   263篇
  1987年   243篇
  1986年   236篇
  1985年   263篇
  1984年   217篇
  1983年   207篇
  1982年   168篇
  1981年   158篇
  1980年   168篇
  1979年   183篇
  1978年   150篇
  1977年   136篇
  1976年   136篇
  1974年   142篇
  1972年   121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Among mutations associated with autosomal dominant and sporadic Parkinson's disease (PD) the G2019S substitution in the leucine-rich repeat kinase 2 (LRRK2) gene is the most frequently identified. To estimate its frequency in Russia, we analyzed 208 patients with PD from the Northwestern region of Russia. Of these, 51 patients were probands from families with PD compatible with autosomal dominant inheritance. The control group represented 161 subjects without neurological disorders settled in the same region. The frequency of the G2019S mutation was greater in familial PD (2 [3.9%] of 51) than in sporadic PD (1 [0.6%] of 157). In addition, this mutation was found in the proband's father, who also had PD, in 1 PD family, and in 1 carrier without signs of PD at age 40 in another PD family. All carriers were heterozygous for the G2019S mutation and reported the Ashkenazi Jewish origin. The mutation was not found in the control group.  相似文献   
62.
OBJECTIVE: To determine the efficacy of a new multilevel surgical protocol for obstructive sleep apnea (OSA). STUDY DESIGN AND SETTING: Sixty patients with moderate to severe OSA because of multilevel pharyngeal obstruction were enrolled into this prospective, controlled clinical trial after clinical examination, endoscopy, and polysomnography. Surgery included uvulaflap, tonsillectomy, hyoid suspension, and radiofrequency treatment of the tongue base (group A). A second group did not receive hyoid suspension (group B). In both groups, nasal surgery was performed if necessary. Polysomnography and Epworth Sleepines Scale (ESS) were recorded at baseline and 2 to 15 months after surgery. RESULTS: In group A, the mean apnea-hypopnea index (AHI) decreased significantly after surgery (38.9 +/- 20.0 vs 20.7 +/- 20.6, P < 0.0001), whereas in group B the AHI did not. All secondary variables (minimal oxygen saturation, mean oxygen saturation, arousal index), and the ESS significantly improved in group A with only changes in arousal index and ESS reaching levels of significance in group B. CONCLUSION: The presented protocol including the hyoid suspension proved to be effective in the treatment of OSA, whereas surgery without hyoid suspension was less successful. EBM rating: B-2b.  相似文献   
63.
A case of a brain stem abscess that was successfully treated using CT guided stereotaxy together with antibiotic therapy is presented. The literature is reviewed and the role of stereotaxy in the treatment of brain stem abscess is discussed.  相似文献   
64.
65.
AIMS: To determine if leucocyte volume distribution analysis (LVDA), obtained using a Coulter Counter Model S Plus IV, can be used to aid differentiation of chronic lymphoproliferative disorder (CLPD) subtypes. METHODS: Mean lymphocyte volume and lymphocyte distribution width were measured on each patient (n = 90) using a hard copy of an amplified LVDA histogram. The mean lymphocyte volume was taken as the mean of the values on either side of the peak at half maximum height. The lymphocyte distribution width was taken as the range of cell values between the two values used to calibrate the mean lymphocyte volume. A template showing typical histograms from commonly occurring CLPD was also produced on an acetate sheet. This was used to examine the histogram from each new patient to evaluate its usefulness as an alternative to the calculation of mean lymphocyte volume and lymphocyte distribution width. RESULTS: Mean lymphocyte volume and lymphocyte distribution width were significantly higher in B cell lymphocytic leukaemia of mixed cell type (B CLL/PL), B cell non-Hodgkin's lymphoma with peripheral blood spill, hairy cell leukaemia and T cell prolymphocytic leukaemia than in B cell chronic lymphocytic leukaemia (B CLL). The mean lymphocyte volume, but not the lymphocyte distribution width, was also significantly higher in T cell chronic lymphocytic leukaemia than in B CLL. The template gave an immediate preliminary indication of possible subtype(s) of disorder and could be used as an alternative to measurement of mean lymphocyte volume and lymphocyte distribution width. CONCLUSIONS: Electronic haematology analysers producing an LVDA provide a useful, cost effective cell sizing analysis which can aid the differentiation of subtypes of CLPD.  相似文献   
66.
Chiropractic fee negotiations in Saskatchewan utilize the Chiropractic Compensation Review Committee with recourse to the Chiropractic Consultation Committee. Health care professionals who practise on a fee for service basis provide the government with a budgetary problem. Although the fees are set, the health care provider can determine his own income by deciding how many visit services he/she wishes to provide. In the fiscal years 1981-82 to 1990-91, chiropractors earned $699.00 per year more than one would expect given the increases in fee schedules. Each chiropractor earned $2,329.00 per year more than was necessary to make up for losses due to inflation. The allegation that unnecessary treatments were performed on patients is countered by analysis of the services per discrete patient values by mode of practice. The increased earnings of chiropractors was accomplished by treating an increasing percentage of the population who sought health care. Comparative information was obtained from the four western provinces.  相似文献   
67.
68.
The tumor microenvironment consists of tumor, immune, stromal, and inflammatory cells which produce cytokines, growth factors, and adhesion molecules that promote tumor progression and metastasis. Of particular interest in this setting is interleukin-1 (IL-1), a pleiotropic cytokine with numerous roles in both physiological and pathological states. It is known to be up regulated in many tumor types and has been implicated as a factor in tumor progression via the expression of metastatic and angiogenic genes and growth factors. A number of studies have reported that high IL-1 concentrations within the tumor microenvironment are associated with a more virulent tumor phenotype. Solid tumors in which IL-1 has been shown to be up regulated include breast, colon, lung, head and neck cancers, and melanomas, and patients with IL-1 producing tumors have generally bad prognoses. The exact mechanisms by which IL-1 promotes tumor growth remain unclear, though the protein is believed to act via induction of pro-metastatic genes such as matrix metalloproteinases and through the stimulation of adjacent cells to produce angiogenic proteins and growth factors such as VEGF, IL-8, IL-6, TNFα, and TGFβ. The IL-1 receptor antagonist (IL-1ra) is a naturally occurring inhibitor to IL-1 and acts by binding to the IL-1 receptor without activating it. The protein has been shown to decrease tumor growth, angiogenesis, and metastases in murine xenograft models. Our focus in this review is to summarize the known data on the role of IL-1 in tumor progression and metastasis and the use of IL-1 inhibition as a novel therapeutic approach in the treatment of solid organ malignancies.  相似文献   
69.
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