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   2814822篇
  免费   198256篇
  国内免费   4278篇
耳鼻咽喉   38548篇
儿科学   90713篇
妇产科学   75666篇
基础医学   417924篇
口腔科学   79338篇
临床医学   248356篇
内科学   545760篇
皮肤病学   64066篇
神经病学   221578篇
特种医学   102806篇
外国民族医学   571篇
外科学   417553篇
综合类   54144篇
现状与发展   12篇
一般理论   968篇
预防医学   225236篇
眼科学   66298篇
药学   210775篇
  11篇
中国医学   5758篇
肿瘤学   151275篇
  2021年   24155篇
  2019年   24840篇
  2018年   34463篇
  2017年   25367篇
  2016年   28121篇
  2015年   31563篇
  2014年   44063篇
  2013年   66081篇
  2012年   92321篇
  2011年   98093篇
  2010年   57447篇
  2009年   53697篇
  2008年   90957篇
  2007年   96743篇
  2006年   97406篇
  2005年   94131篇
  2004年   89946篇
  2003年   86258篇
  2002年   83460篇
  2001年   124852篇
  2000年   128275篇
  1999年   107614篇
  1998年   31202篇
  1997年   27171篇
  1996年   27629篇
  1995年   25949篇
  1994年   23900篇
  1993年   22547篇
  1992年   82739篇
  1991年   80938篇
  1990年   79324篇
  1989年   76353篇
  1988年   70200篇
  1987年   68933篇
  1986年   64538篇
  1985年   61944篇
  1984年   46015篇
  1983年   39231篇
  1982年   23218篇
  1979年   42959篇
  1978年   30786篇
  1977年   25673篇
  1976年   24546篇
  1975年   26722篇
  1974年   32088篇
  1973年   30605篇
  1972年   28764篇
  1971年   27476篇
  1970年   25376篇
  1969年   24208篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
BACKGROUND: This study examines trends in the presentation and surgical management of acute diabetic foot problems in a single institution. METHOD: Prospective audit of all diabetic patients who had a primary procedure for critical lower limb ischaemia (CLI) and/or foot sepsis between 1st January 1990 and 31st December 2002. Primary and secondary intervention, mortality and limb salvage rate within 6 weeks of the index procedure were recorded. RESULTS: There were 661 patients (417 men and 244 women of median age 69, range 31-99, years) with 799 affected limbs. CLI alone was present in 625 (78%) limbs, combined CLI and foot sepsis in 53 (7%) and foot sepsis alone in 121 (15%). The primary intervention was minor amputation in 323 (40%) limbs, revascularisation in 288 (36%), major amputation in 185 (23%) and sympathectomy in three limbs. Within 6 weeks, 125 (16%) limbs required secondary intervention, the peri-procedural mortality rate was 38 of 924 (4%), and the limb salvage rates for patients with CLI, combined CLI and sepsis and sepsis alone were 66, 66 and 80%, respectively. There was a significant decline in the proportion of patients presenting with CLI alone and a significant increase in the proportion presenting with combined CLI and sepsis and sepsis alone. In patients with CLI alone, there was a significant increase in the primary major amputation rate and a significant decline in the minor amputation rate with no significant change in the revascularisation rate. CONCLUSION: There has been a progressive decline in the proportion of patients presenting with CLI alone and a greater proportion of patients presenting with an element of foot sepsis. In patients with CLI alone, the primary major amputation rate has increased at the expense of a decline in minor amputation rate.  相似文献   
95.
96.
97.
Burkitt’s lymphoma is a high-grade, rapidly growing B-cell neoplasm. It is recognized by its aggressive course, brief median survival, and low rates of long-term survival. The authors discuss the case of a patient who acutely presented with intraabdominal complications from a new onset of Burkitt’s lymphoma. The clinical and pathological features, staging, treatment options, and survival data are reviewed. In addition, the role of surgical intervention is carefully analyzed.  相似文献   
98.
Glutathione-S-transferase (GST) genes encode a family of detoxification enzymes that offer protection against endogenous and exogenous sources of reactive oxygen species (ROS). Germline variations in GST genes may alter the catalytic efficiency of GST isoenzymes leading to a potential increase in susceptibility to the genotoxic effects of ROS and electrophilic substances. A nested case-control study design was used to examine the association between the polymorphic GST genes and prostate cancer risk among Finnish male smokers of the ATBC Cancer Prevention Study. A case-case analysis was used to determine the association between these genetic polymorphisms and prostate cancer progression. Germline DNA was obtained from 206 prostate cancer cases and 194 controls frequency matched on age, intervention group and study clinic. Cases and controls were genotyped for three GST genes using MALDI-TOF mass spectrometry or multiplex polymerase chain reaction (PCR). Relative to the wild-type genotype, we observed a 36% reduction in prostate cancer risk associated with the GST-M1-null genotype (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.43, 0.95). Unlike GST-M1, GST-T1-null (OR 0.74, 95% CI 0.42, 1.33) and GST-P1*B (OR 1.10, 95% CI 0.72, 1.69) were not strongly associated with prostate cancer risk. We did not observe any significant associations between the selected polymorphic GST genes and tumour grade or stage. In conclusion, we did not observe a direct association between polymorphic GST-T1 or GST-P1 and prostate cancer risk. Our observation of a relatively strong inverse association between the GST-M1-null genotype and prostate cancer risk needs to be confirmed in larger association studies.  相似文献   
99.
Constitutional trisomy 21 is the most prominent predisposing factor to childhood leukemia, whereas the t(12;21)(p13;q22) with its molecular genetic counterpart, the TEL/AML1 fusion gene, is the most common acquired chromosomal rearrangement in childhood B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). Thus, it was somewhat surprising that according to the currently available literature the incidence of TEL/AML1+ BCP ALL is extremely low in patients with Down syndrome (DS). To further investigate this issue in a population-based fashion, the authors retrospectively assessed the number of DS patients with a TEL/AML1+ ALL in two consecutive Austrian ALL multicenter trials. Accordingly, they were able to analyze 8 of 10 individuals with DS and a BCP ALL, including 2 who suffered from a TEL/AML1+ leukemia. Based on this observation we concluded that individuals with a constitutional trisomy 21 may have the similar likelihood to develop a TEL/AML1+ leukemia as BCP ALL patients without this specific predisposing factor.  相似文献   
100.
Medullary thyroid carcinoma (MTC) is a rare form of thyroid cancer representing about 10% of all thyroid malignancies. It occurs mostly as a sporadic tumor or in association with autosomal dominant inherited cancer syndromes--multiple endocrine neoplasia (MEN) types 2A and 2B and familial MTC. Germline mutations in exons 8, 10, 11, 13, 14, 15 and 16 of the RET proto-oncogene are found in most of the familial cases. There are only a few published data reporting multiple germline mutations in the RET proto-oncogene. We have detected double germline mutations in 2 different exons on the same RET allele in two MEN 2 families. In the MEN 2A family, double germline mutation in exons 10 (Cys620Phe) and 13 (Tyr791Phe) was detected. In the MEN 2B family, beside the classical germline mutation in exon 16 (Met918Thr) a second germline mutation in exon 13 (Tyr791Phe) was found. This study revealed that MEN 2 syndromes can also be caused by double germline mutations in the RET proto-oncogene and these families can be added to small worldwide cohort of families with multiple germline mutations.  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