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   2603930篇
  免费   186004篇
  国内免费   7699篇
耳鼻咽喉   34497篇
儿科学   85743篇
妇产科学   72010篇
基础医学   365198篇
口腔科学   70172篇
临床医学   235886篇
内科学   519093篇
皮肤病学   62793篇
神经病学   214199篇
特种医学   100458篇
外国民族医学   744篇
外科学   389491篇
综合类   50749篇
现状与发展   6篇
一般理论   987篇
预防医学   197325篇
眼科学   57150篇
药学   189408篇
  8篇
中国医学   5443篇
肿瘤学   146273篇
  2021年   20962篇
  2019年   21282篇
  2018年   30179篇
  2017年   23130篇
  2016年   26759篇
  2015年   30113篇
  2014年   41206篇
  2013年   61380篇
  2012年   81533篇
  2011年   85819篇
  2010年   51679篇
  2009年   49726篇
  2008年   79850篇
  2007年   84710篇
  2006年   86319篇
  2005年   82412篇
  2004年   79346篇
  2003年   76559篇
  2002年   73803篇
  2001年   128563篇
  2000年   131481篇
  1999年   110647篇
  1998年   31351篇
  1997年   27997篇
  1996年   28280篇
  1995年   27443篇
  1994年   25107篇
  1993年   23450篇
  1992年   85218篇
  1991年   81618篇
  1990年   78840篇
  1989年   76116篇
  1988年   69514篇
  1987年   68044篇
  1986年   63592篇
  1985年   60563篇
  1984年   44979篇
  1983年   37989篇
  1982年   22484篇
  1981年   20011篇
  1979年   38992篇
  1978年   27460篇
  1977年   23279篇
  1976年   21512篇
  1975年   22831篇
  1974年   26805篇
  1973年   25383篇
  1972年   23761篇
  1971年   21966篇
  1970年   20194篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
BACKGROUND: Three dimensional skin equivalents are widely used in dermatopharmacological and toxicological studies and as autologous transplants in wound healing. In pharmacology, there is tremendous need for monitoring the response of engineered skin equivalents to external treatment. Transplantation of skin equivalents for wound healing requires careful verification of their quality prior to transplantation. Optical coherence tomography (OCT) is a non-contact, non-destructive imaging technique for living tissues offering the potential to fulfill these needs. This work presents an analysis of OCT for high-resolution monitoring of skin equivalents at different stages during the culture process. METHODS: We developed a high-resolution OCT imaging setup based on a commercially available OCT system. A broadband femtosecond laser light source replaces the original superluminescence diode. Tomograms of living skin equivalents were recorded with an axial resolution of 3 mum and correlated with histology and immunofluorescence images. Comparison with standard low-resolution OCT is presented to emphasize the advantages of high-resolution OCT for this application. RESULTS: OCT is particularly able to distinguish between different layers of skin equivalents including stratum corneum, epidermal and dermal layer as well as the basement membrane zone. The high-resolution OCT scans correlate closely with two key benchmarks, histology and immunofluorescence imaging. CONCLUSIONS: This study clearly demonstrates the benefits of high-resolution OCT for identifying living tissue structure and morphology. Compared with the current gold standard histology, OCT offers non-destructive tissue imaging, enabling high-resolution evaluation of living tissue morphology and structure as it evolves.  相似文献   
65.
BACKGROUND/AIMS: The purpose of this work was to develop a new sensor for objective in vivo measurement of the cutaneous temperature based on micro-electro-mechanical systems (MEMS), and to compare these performances with those of a classical thermocouple. Research on this new sensor was carried out to allow the quantification of the thermal properties of the made-up skin. METHODS: Sixteen female subjects divided into two different age groups (18-35 and >50 years old) were recruited for this study. Several zones of the face and forearms were made up at random with foundations containing or not a thermoregulator raw material. The quantity of foundation applied on the skin was standardized and measurements were carried out first before make-up, and then 10 s and 5 min after make-up. The new sensor and the thermocouple were used successively on each zone. The cutaneous temperature was expressed in degrees celsius. RESULTS/CONCLUSION: The two systems are similar in terms of repeatability and reproducibility, with some differences in sensibility. The data measured by the MEMS sensor appear lower than those measured by the thermocouple. After make-up, the MEMS sensor detects a progressive increase of the temperature in time whereas the thermocouple detects a decrease. We found the same evolution on the face but in a more attenuated way. These results tend to show that the devices do not measure the same phenomenon. The thermocouple appears more sensitive to the thermal response of the made-up surface whereas the MEMS sensor appears more sensitive to the heat transfers in the interface between the skin and make-up.  相似文献   
66.
We report the case of a 38-year-old woman who presented with chronic lower abdominal pain. Her past medical history included a splenectomy due to abdominal trauma. Ultrasound examination revealed four pelvic tumors which, upon laparotomy, were found to be the result of splenosis. Approximately 100 cases of splenosis have been reported but only a minority of them have been published in the gynecological literature. Our case indicates that those involved in pelvic scanning (even of asymptomatic women) and/or treating those complaining of lower abdominal pain or presenting with pelvic tumors should be aware of splenosis as a possible diagnosis.  相似文献   
67.
Although surgical lung resection could improve prognosis in some patients with multidrug-resistant tuberculosis (MDR-TB), there are no reports on the optimal candidates for this surgery. The aim of the present study was to elucidate the prognostic factors for surgery in patients with MDR-TB. Patients who underwent lung resection for the treatment of MDR-TB between March 1993 and December 2004 were included in the present study. Treatment failure was defined as greater than or equal to two of the five cultures recorded in the final 12 months of treatment being positive, any one of the final three cultures being positive, or the patient having died during treatment. The variables that affected treatment outcomes were identified through univariate and multivariate logistic regression analysis. In total, 79 patients with MDR-TB were included in the present study. The treatment outcomes of 22 (27.8%) patients were classified as failure. A body mass index <18.5 kg x m(-2), primary resistance, resistance to ofloxacin and the presence of a cavitary lesion beyond the range of the surgical resection were associated with treatment failure. Low body mass index, primary resistance, resistance to ofloxacin and cavitary lesions beyond the range of resection are possible poor prognostic factors for surgical lung resection in multidrug-resistant tuberculosis patients.  相似文献   
68.
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation.  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