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   96384篇
  免费   4748篇
  国内免费   352篇
耳鼻咽喉   1804篇
儿科学   3303篇
妇产科学   2009篇
基础医学   12534篇
口腔科学   3111篇
临床医学   6410篇
内科学   23286篇
皮肤病学   3200篇
神经病学   7873篇
特种医学   2229篇
外国民族医学   1篇
外科学   12079篇
综合类   722篇
一般理论   28篇
预防医学   9332篇
眼科学   2186篇
药学   6516篇
中国医学   592篇
肿瘤学   4269篇
  2023年   695篇
  2022年   1471篇
  2021年   3255篇
  2020年   1528篇
  2019年   2985篇
  2018年   3802篇
  2017年   2282篇
  2016年   2115篇
  2015年   2205篇
  2014年   3193篇
  2013年   4650篇
  2012年   6921篇
  2011年   7518篇
  2010年   4064篇
  2009年   3150篇
  2008年   5567篇
  2007年   5731篇
  2006年   5313篇
  2005年   5377篇
  2004年   4900篇
  2003年   4599篇
  2002年   4182篇
  2001年   2645篇
  2000年   3110篇
  1999年   2125篇
  1998年   666篇
  1997年   559篇
  1996年   433篇
  1995年   384篇
  1994年   333篇
  1993年   269篇
  1992年   591篇
  1991年   486篇
  1990年   465篇
  1989年   370篇
  1988年   368篇
  1987年   331篇
  1986年   277篇
  1985年   287篇
  1984年   191篇
  1983年   183篇
  1982年   158篇
  1981年   154篇
  1980年   121篇
  1979年   155篇
  1978年   134篇
  1974年   114篇
  1973年   89篇
  1971年   97篇
  1969年   94篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
53.
Pituitary metastases of solid tumours are infrequent, specially as a first manifestation. When they happen, they are usually due to breast or lung cancer and are asymptomatic or produce diabetes insipidus. It is very strange that they produce hormonal deficiency. We present a case report of a bronchogenic adenocarcinoma in a 65-year-old man which began with panhypopituitarism, diabetes insipidus and visual alterations. Magnetic resonance imaging revealed a large sellar mass, with clivus infiltration and invading the right cavernous sinus. The biopsy result was adenocarcinoma metastases from lung cancer.  相似文献   
54.
55.
Oxidative stress, defined as an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense, is considered to be an important pathogenic factor in diabetes mellitus and its complications. In diabetic state, ROS might also be implicated in promoting a state of systemic inflammation. Recently, it was demonstrated that antioxidant therapy could be used to stop the initiation and propagation of this inflammatory response. Repaglinide is a new oral antidiabetic agent with a possible antioxidant activity. Therefore, in the present study, a possible therapeutic value of repaglinide in ameliorating the oxidative and inflammatory processes was tested in diabetic animals. In the study, the levels of total antioxidant status (TAS), ascorbic acid (AA), protein carbonyl groups (PCG) and interleukin-6 (IL-6) were determined in plasma of diabetic rabbits after 4 and 8 weeks of repaglinide treatment (1mg daily). Ex vivo analysis revealed that there were significant differences in these markers between hyperglycemic and control animals (P<0.05). Some of these parameters were ameliorated by repaglinide treatment. In diabetic rabbits treated with repaglinide, protein oxidation was diminished by 17.8% after 8 weeks of experiment. The level of AA in plasma of diabetic treated animals was higher than in non-treated diabetic groups (by 9.4 and 22.6% after 4 and 8 weeks, respectively). In diabetic treated animals, the TAS level was also significantly increased (by 23.6 and 16.7%). However, in diabetic rabbits, repaglinide did not affect the concentration of IL-6.  相似文献   
56.
57.
Percutaneous embolization of large portosystemic collaterals was performed in three patients following placement of a transjugular intrahepatic portosystemic shunt in order to improve hepatopetal portal flow. Improved hepatic portal perfusion was achieved in these cases, thereby theoretically reducing the risk of chronic hepatic encephalopathy.  相似文献   
58.
The protein Sex-lethal (SXL) controls pre-mRNA splicing of two genes involved in Drosophila sex determination: transformer (tra) and the Sxl gene itself. Previous in vitro results indicated that SXL antagonizes the general splicing factor U2AF65 to regulate splicing of tra. In this report, we have used transgenic flies expressing chimeric proteins between SXL and the effector domain of U2AF65 to study the mechanisms of splicing regulation by SXL in vivo. Conferring U2AF activity to SXL relieves its inhibitory activity on tra splicing but not on Sxl splicing. Therefore, antagonizing U2AF65 can explain tra splicing regulation both in vitro and in vivo, but this mechanism cannot explain splicing regulation of Sxl pre-mRNA. These results are a direct proof that Sxl, the master regulatory gene in sex determination, has multiple and separable activities in the regulation of pre-mRNA splicing.  相似文献   
59.
A total of 186 blood samples from 24 HIV-1 seropositive hemophiliac patients, monitored every four months for 29 months, were investigated for the presence of viral antigen in plasma. In addition, peripheral blood mononuclear cells (PBMC) were cultured for HIV-1, using normal PBMC as a target for replication. Antigenemia was detected in 51 % of the patients and from PBMC in 87.5 % of the patients. The incidence of HIV isolation in asymptomatic patients (42.8 %) was similar to that found in symptomatic patients (51.4 %). Patients with opportunistic infections had a higher incidence of lymphocytic viremia (p<0.05). Plasma viremia was closely associated (p<0.05) with low CD4+ counts and infection progression. The persistence of antigenemia was also a marker of a poor clinical course. In treated patients, plasma viremia was the marker that better correlated with the clinical course, and it did not appear during the first nine months of therapy. Zidovudine doses of >500 mg/day significantly lowered the appearance of antigenemia and lymphocytic viremia (p<0.05).  相似文献   
60.
Congenital “healed” cleft lip (CHCL) is an unusual anomaly including a paramedian “scar” of the upper lip, which appears as if a typical cleft lip has been corrected in utero. The CHCL is frequently associated with an ipsilateral notch in the vermilion, and “collapsed” nostril. Twenty-five CHCL cases are presented, eighteen of which were an isolated malformation found among the 3,950,715 births examined in two similar birth defect registries: ECEMC in Spain and ECLAMC in Latin America. Like open cleft lip, of which it seems to be a variant, CHCL is most frequently seen among males (14/18 isolated cases), it preferentially affects the left side (10/18 cases), and it segregated together with cleft lip in one family. The five CHCL cases with other congenital anomalies included: two cases with hydrocephalus, two VACTERL associations, and one atypical oblique facial cleft infant with single umbilical artery. CHCL may result from a defective fusion of the frontonasal and maxillary processes (before week 7 of embryonic life), or from a spontaneously repaired open cleft lip, later on. In either way, these cases heal with a visible scar, and the pre-occurrence of CHCL in two families suggests a familial predisposition to this phenomenon. © 1995 Wiley-Liss, Inc.  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