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   3494274篇
  免费   271591篇
  国内免费   6819篇
耳鼻咽喉   49692篇
儿科学   111787篇
妇产科学   94654篇
基础医学   491714篇
口腔科学   103035篇
临床医学   318674篇
内科学   674852篇
皮肤病学   74837篇
神经病学   284094篇
特种医学   136394篇
外国民族医学   1084篇
外科学   529401篇
综合类   83816篇
现状与发展   5篇
一般理论   1394篇
预防医学   276367篇
眼科学   83905篇
药学   261581篇
  11篇
中国医学   7283篇
肿瘤学   188104篇
  2018年   37571篇
  2017年   28716篇
  2016年   31768篇
  2015年   35997篇
  2014年   51165篇
  2013年   76933篇
  2012年   104766篇
  2011年   110745篇
  2010年   65587篇
  2009年   61946篇
  2008年   104128篇
  2007年   110937篇
  2006年   111881篇
  2005年   108539篇
  2004年   104511篇
  2003年   100095篇
  2002年   97872篇
  2001年   166526篇
  2000年   171595篇
  1999年   143892篇
  1998年   38784篇
  1997年   34265篇
  1996年   33979篇
  1995年   34930篇
  1994年   32646篇
  1993年   30252篇
  1992年   114664篇
  1991年   111144篇
  1990年   107226篇
  1989年   103558篇
  1988年   95603篇
  1987年   93923篇
  1986年   88778篇
  1985年   84721篇
  1984年   63712篇
  1983年   54215篇
  1982年   32083篇
  1981年   28621篇
  1979年   58663篇
  1978年   40956篇
  1977年   34743篇
  1976年   32535篇
  1975年   34367篇
  1974年   42342篇
  1973年   40407篇
  1972年   37861篇
  1971年   34959篇
  1970年   32828篇
  1969年   30551篇
  1968年   28059篇
排序方式: 共有10000条查询结果,搜索用时 25 毫秒
991.
The mainstays of treatment for colorectal liver metastases (CRLMs) are surgery and chemotherapy. Chemotherapeutic benefits of tumor shrinkage and systemic control of micrometastases are in part counterbalanced by chemotoxicity that can modify the liver parenchyma, jeopardizing the detection of CRLM. This review addresses the clinical decision-making process in the context of radiographic and pathologic responses, the preoperative imaging workup, and the approaches to the liver for CRLM, which disappear after systemic chemotherapy.  相似文献   
992.
Cancer is one of the major public health problems in our society. It is estimated that more than 18 million new cases are diagnosed worldwide every year; 280,000 in Spain. Incidence in following a growing trend. This epidemic could be controlled with research into new treatments and, above all, with adequate prevention. Primary prevention could prevent avoid up to half of all cases. For many others, secondary prevention is essential, as it make diagnosis possible in the stages of the disease when it is easily curable. These guidelines present the scientific evidence regarding secondary prevention in tumors in which its use is well-accepted: breast, cervical, colorectal, prostate, lung, ovarian, melanoma, and gastric cancer.  相似文献   
993.
994.
Background: Breast cancer is a multifactorial disease that affects women worldwide. Its progression is likely to be executed by oxidative stress wherein elevated levels of reactive oxygen and nitrogen species drive several breast cancer pathologies. Spider venom contains various pharmacological peptides which exhibit selective activity to abnormal expression of ion channels on cancer cell surface which can confer potent anti-cancer activities against this disease. Methods: Venom was extracted from a Philippine tarantula by electrostimulation and fractionated by reverse phase-high performance liquid chromatography (RP-HPLC). Venom fractions were collected and used for in vitro analyses such as cellular toxicity, morphological assessment, and oxidative stress levels. Results: The fractionation of crude spider venom generated several peaks which were predominantly detected spectrophotometrically and colorimetrically as peptides. Treatment of MCF-7 cell line of selected spider venom peptides induced production of several endogenous radicals such as hydroxyl radicals (•OH), nitric oxide radicals (•NO), superoxide anion radicals (•O2−) and lipid peroxides via malondialdehyde (MDA) reaction, which is comparable with the scavenging effects afforded by 400 µg/mL vitamin E and L-cysteine (p<0.05). Concomitantly, the free radicals produced decrease the mitochondrial membrane potential and metabolic activity as detected by rhodamine 123 and tetrazolium dye respectively (p>0.05). This is manifested by cytotoxicity in MCF-7 cells as seen by increase in membrane blebbing, cellular detachment, caspase activity and nuclear fragmentation. Conclusion: These data suggest that the Philippine tarantula venom contains peptide constituents exhibiting pro-oxidative and nitrosative-dependent cytotoxic activities against MCF-7 cells and can indicate mechanistic insights to further explore its potential application as prooxidants in cancer therapy.  相似文献   
995.
996.
Activities of tedizolid and comparators were evaluated against gram-positive isolates responsible for skin and skin structure infections, pneumonia, and bloodstream infections. Non-duplicate gram-positive isolates (8011) were collected from 20 European countries/regions.

Tedizolid (0.12?mg/L) showed similar results of minimum inhibitory concentration required to inhibit the growth of 50% of organisms (MIC50) regardless of pathogen/group or infection type, except for coagulase-negative staphylococci, Enterococcus faecalis, and viridans group streptococci (VGS), against which tedizolid had MIC50 values of 0.06, 0.25, and 0.06?mg/L, respectively. Similar results of tedizolid MIC50 and minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) (MIC50/90, 0.12/0.12?mg/L) were obtained against methicillin-resistant Staphylococcus aureus and methicillin-susceptible S. aureus. Tedizolid, linezolid, and daptomycin were active against enterococci. Tedizolid (MIC90, 0.12–0.25?mg/L), ceftaroline (MIC90, 0.12?mg/L), and vancomycin (MIC90, 0.25–0.5?mg/L) had the lowest MIC90 values against Streptococcus pneumoniae and VGS, whereas ceftaroline (MIC90, ≤0.015?mg/L), penicillin (MIC90, ≤0.06?mg/L), ceftriaxone (MIC90, ≤0.06–0.12?mg/L), and tedizolid (MIC90, 0.12?mg/L) were the most potent against β-haemolytic streptococci.

Tedizolid displayed potent activity against gram-positive isolates from Europe, regardless of infection type.  相似文献   

997.
998.
999.
1000.
Personalised cancer treatment depends on identification of therapeutically relevant biological subgroups of patients for assessing effect of treatment and to discover new therapeutic options. By analyses in heterogeneous patient populations, the effects may be lost in noise. Squamous cell carcinoma of the lung is a major killer worldwide. Despite recent advances, mortality is high and response to therapies varies greatly from patient to patient. Target search in biologically relevant subgroups may identify treatment options not so far discovered. A total of 198 patients undergoing surgery for squamous cell carcinomas of the lung were included in the study. The tumours were analysed for copy number alterations (n = 152) and gene expression from tumour (n = 188) and normal lung (n = 21), with both data levels present in 140 patients. We studied alterations in tumours harbouring mutations in TP53 and in previously published gene expression subtypes. Genes with consistent alterations in both genomic levels were identified as putative biomarkers. Results were validated in TCGA. The most convincing biomarker in TP53 mutated squamous cell carcinomas of the lung was BIRC5 with amplification in 36% of mutated samples, 5% in wild-type samples and a 17%-fold change of expression between TP53 mutated tumours and normal lung tissue. BIRC5 was significantly altered in the classical and primitive subtypes. We suggest BIRC5 as a putative predictive biomarker and putative druggable target in squamous cell lung carcinomas harbouring TP53 mutation or classified as classical and primitive subtypes.  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