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   47270篇
  免费   3602篇
  国内免费   192篇
耳鼻咽喉   567篇
儿科学   997篇
妇产科学   964篇
基础医学   6590篇
口腔科学   1001篇
临床医学   4683篇
内科学   9886篇
皮肤病学   1077篇
神经病学   4534篇
特种医学   1958篇
外国民族医学   2篇
外科学   8593篇
综合类   479篇
一般理论   76篇
预防医学   2652篇
眼科学   935篇
药学   2791篇
中国医学   75篇
肿瘤学   3204篇
  2023年   421篇
  2022年   749篇
  2021年   1712篇
  2020年   1017篇
  2019年   1345篇
  2018年   1522篇
  2017年   1024篇
  2016年   1198篇
  2015年   1379篇
  2014年   1869篇
  2013年   2177篇
  2012年   3550篇
  2011年   3501篇
  2010年   1945篇
  2009年   1724篇
  2008年   2726篇
  2007年   2781篇
  2006年   2585篇
  2005年   2404篇
  2004年   2224篇
  2003年   2030篇
  2002年   1859篇
  2001年   524篇
  2000年   515篇
  1999年   535篇
  1998年   430篇
  1997年   339篇
  1996年   253篇
  1995年   247篇
  1994年   208篇
  1993年   212篇
  1992年   365篇
  1991年   337篇
  1990年   308篇
  1989年   270篇
  1988年   258篇
  1987年   242篇
  1986年   234篇
  1985年   261篇
  1984年   216篇
  1983年   204篇
  1982年   168篇
  1981年   158篇
  1980年   168篇
  1979年   182篇
  1978年   150篇
  1977年   136篇
  1976年   135篇
  1974年   142篇
  1973年   121篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
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   
162.
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   
163.
OBJECTIVE: Haematological and biochemical measurements are performed routinely before surgery to exclude organ malfunction and blood cell and coagulation abnormalities. We aimed to test routinely obtained laboratory data as factors predicting operative risk. METHODS: Between 1996 and 2003, 2198 patients underwent aortic valve replacement (AVR) (908 of them with concomitant CABG) in our institute. The mean age of the study population was 69+/-11 years (range 13-91, 43% female). Clinical and laboratory parameters based on the consolidated data mart set were evaluated by multiple logistic regression analysis. RESULTS: The overall operative mortality (within 30 days) was 3.8% and the mortality after 3 months was 5.9%. In addition to clinical characteristics, the following laboratory values were identified as independent predictors of 30-day mortality: fasting blood glucose, antithrombine III, partial thromboplastine time and creatinine kinase. As independent predictors of 3-month mortality, the following laboratory values were indentified: fasting blood glucose, serum creatinine, antithrombine III, partial thromboplastine time, lactate dehydrogenase, sodium concentration and serum proteins. The discriminative power of the models increased if laboratory parameters were included in addition to preoperative clinical characteristics (from 0.75 to 0.79 and from 0.75 to 0.78 for 30-day and 3-month mortality, respectively). The discriminative power using the logistic EuroScore was lower (0.71 and 0.7, for 30-day and 3-month mortality, respectively). CONCLUSIONS: Laboratory parameters as objective markers for organ function and nutritional status are useful data for the prediction of 30-day and 3-month mortality after aortic valve replacement. Using modern methods of information technology, these valuable data which are stored electronically in most hospitals, can be used efficiently for research and quality control.  相似文献   
164.
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   
165.
166.
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   
167.
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   
168.
169.
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   
170.
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