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   18445篇
  免费   1191篇
  国内免费   79篇
耳鼻咽喉   121篇
儿科学   534篇
妇产科学   455篇
基础医学   2804篇
口腔科学   600篇
临床医学   1416篇
内科学   4551篇
皮肤病学   363篇
神经病学   1797篇
特种医学   440篇
外国民族医学   2篇
外科学   1818篇
综合类   75篇
一般理论   6篇
预防医学   1740篇
眼科学   396篇
药学   1303篇
中国医学   101篇
肿瘤学   1193篇
  2023年   133篇
  2022年   313篇
  2021年   549篇
  2020年   319篇
  2019年   498篇
  2018年   671篇
  2017年   380篇
  2016年   501篇
  2015年   548篇
  2014年   726篇
  2013年   900篇
  2012年   1403篇
  2011年   1479篇
  2010年   729篇
  2009年   678篇
  2008年   1112篇
  2007年   1187篇
  2006年   1077篇
  2005年   988篇
  2004年   841篇
  2003年   870篇
  2002年   796篇
  2001年   319篇
  2000年   301篇
  1999年   259篇
  1998年   154篇
  1997年   121篇
  1996年   119篇
  1995年   87篇
  1994年   77篇
  1993年   87篇
  1992年   153篇
  1991年   113篇
  1990年   112篇
  1989年   101篇
  1988年   95篇
  1987年   83篇
  1986年   85篇
  1985年   73篇
  1984年   70篇
  1983年   48篇
  1982年   33篇
  1981年   43篇
  1980年   33篇
  1979年   36篇
  1978年   33篇
  1977年   25篇
  1976年   25篇
  1975年   25篇
  1974年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Bacterial infection in cirrhotic patients and its relationship with alcohol   总被引:3,自引:0,他引:3  
OBJECTIVE: Infections are regarded as a major complication and an important cause of death in cirrhotics. Alcohol is a predisposing factor to infections in such patients. This study was undertaken to compare the frequency and evolution of bacterial infection among alcoholic and nonalcoholic cirrhotics. METHODS: To observe this relationship, we retrospectively studied a cohort of 382 cirrhotic inpatients, 201 of whom were alcoholic (alcohol intake > or =80 g/day for > or =10 yr) and 181 of whom were nonalcoholic. RESULTS: A total of 128 (33.5%) patients presented with infection upon hospitalization, 78 of whom were alcoholic and 50 of whom were nonalcoholic (p = 0.02). A total of 157 cases of infection were diagnosed, with spontaneous bacterial peritonitis as the most prevalent one (54.1%), followed by pneumonia (18.5%), infection of the soft parts (10.8%), and urinary tract infection (7.0%). Infection and deaths were more frequent in patients with Child-Pugh C than in those with Child-Pugh A/B (p = 0.003, p = 0.0002 respectively). Alcoholic patients with Child-Pugh A/B were more susceptible to infection compared to nonalcoholic patients (p = 0.02), although no difference was noted as to the number of deaths (p = 0.1). With regard to patients with Child-Pugh C, no statistical difference was found in the infections or deaths among alcoholics and nonalcoholics (p = 0.8, p = 0.8). CONCLUSIONS: Our findings suggest that, despite the fact that bacterial infections are more common in cirrhotic alcoholics, its seems that the mortality rate is associated more with the severity than with the etiology of the hepatic disease.  相似文献   
992.
993.
Plants of the genus Hibiscus thrives produce a diversity of molecules with bioactive properties. In a previous study of Hibiscus tiliaceus L. methanolic extract (HME) using bacteria and yeast, as test media, it has been shown that HME strongly inhibited the mutagenic action of H2O2 or tert-butyl-hydroperoxide (t-BHP). Here, our interest is to evaluate the genotoxicity and the antigenotoxic/antimutagenic properties of HME using oxidative challenge with H2O2 and t-BHP in V79 cells. We determined cytotoxicity using clonal survival assay; evaluated DNA damage using the comet assay and the micronucleus test in binucleated cells besides of the lipid peroxidation degree and the reduced glutathione content. We examined the ability of HME in quenching hydroxyl radical by means of a HPLC-based method utilizing the hypoxanthine/xanthine oxidase assay. At concentrations ranging from 0.001 to 0.1 mg/mL, HME was not cytotoxic, genotoxic or mutagenic. Treatment with non-cytotoxic concentrations of HME increased cell survival after H2O2 and t-BHP exposure and prevented DNA damage. The pre-treatment with HME also was able to decrease the mutagenic effect of these genotoxins, evaluated using the micronucleus test. HME prevented the increase in lipid peroxidation and decrease in GSH content in response to the oxidative challenge. Therefore, the ability in preventing against H2O2- and t-BHP-induced GSH depletion and lipid peroxidation was probably a major contribution to the cytoprotective effects. Moreover, HME acts as a hydroxyl radical scavenger. In summary, HME did not have a harmful or inhibitory effect on the growth of V79 cells and presented antioxidant activity, consequently, both antigenotoxic and antimutagenic effects against oxidative DNA damage.  相似文献   
994.
Objectives This paper presents an outcome of pharmacist counseling among Malaysian smokers for their awareness of and willingness to quit smoking. Method It was a cross-sectional study during a 3-day public health campaign at a shopping complex. Each self-referred participant was asked to complete a questionnaire apart from the question regarding improvement, and if any in their awareness and willingness to quit smoking, were asked to respond after counseling. Pharmacists counseled each participant about smoking cessation strategies and smoking related diseases. The data were analyzed by χ 2 test. Results Among respondents, 25.5% had been smoking for more than 10 years, 31% for 5–10 years, 25.4% for 2–5 years and 18.3% for 1–2 years. The participants declaring no awareness about smoking were 22.9%, with little awareness 44.3%, having moderate awareness 25.7% and with considerable awareness were 7.1%. After counseling, 4.1% revealed unawareness, 17.8% little awareness, 43.8% moderate and 34.2% had considerable awareness on the above aspects. The post counseling awareness on smoking was observed to be significantly higher (P< 0.01). Among smokers studied, 67% showed willingness to quit smoking. Conclusion Increase in awareness of and willingness to quit smoking reflects that pharmacist counseling seems to be helpful in cessation of smoking.  相似文献   
995.
996.
The present report describes the use of molecular probes to investigate the chromosomal constitution of interphase nuclei of formalin-fixed, paraffin-embedded tissue from three infants with multiple congenital malformations and a provisional diagnosis of trisomy 13 in two. Fluorescent in situ hybridization with the probe for the 13 and 21 centromeric regions revealed five nuclear signals in two of the cases, indicating the presence of an extra chromosome, and only four nuclear signals in the other case. Only the two positive cases had phenotypic features consistent with trisomy 13. Routine cytogenetic analysis was performed on one child and confirmed an additional chromosome 13. The child without an extra chromosome had features consistent with Ivemark syndrome. This study demonstrates the utility of fluorescent DNA probes for the retrospective diagnosis of aneuploidies in archival material.  相似文献   
997.
Eight families with two or more first-degree relatives affected with ovarian carcinoma were identified among a series of 138 consecutive ovarian cancer patients. History of breast cancer was reported in six of the eight families. Five of 19 patients with familial cancer developed ovarian cancer as a second primary tumor following breast carcinoma, whereas only 6/130 sporadic cases had a previous history of breast cancer. No significant difference was detected in clinical and pathological features between sporadic and familial cases. However, in three high-risk families ovarian cancer tended to develop at a younger age compared with other familial cases and with sporadic occurrences, and nulliparity was less frequent in the familial group. These observations emphasize the need to take into account multiple factors-in addition to positive family history-for the evaluation of genetic predisposition to ovarian carcinoma.  相似文献   
998.
Primary breast tumors were tested for loss of heterozygosity (LOH), on chromosome 9p with microsatellite markers restricted to a 28 cM region including the MTS1 gene. LOH was found with at least I marker in 38% of the 201 cases analyzed. A high frequency of deletions was detected at the 9p23-p21 region, indicating a tumor suppressor gene(s) important for breast cancer tumorigenesis. Tumors with and without LOH on 9p were compared with respect to clinico-pathological factors using X2 analysis. Tumors with 9p LOH were significantly associated with high S-phase status and aneuploidy, but not with type, node status, estrogen and progesterone receptor content or age of the patients at diagnosis. Survival analysis showed that LOH at 9p did not significantly affect the survival rate of breast cancer patients. Our results indicate that the aberrations on 9p detected in this study are not of independent prognostic value. A significant association was found between LOH at 9p and LOH at chromosomal arms 3p and 6q, which is an additional contribution toward understanding the genetic events in breast tumor pathogenesis. © 1995 Wiley-Liss, Inc.  相似文献   
999.
1000.
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