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   1968篇
  免费   95篇
  国内免费   7篇
耳鼻咽喉   13篇
儿科学   75篇
妇产科学   34篇
基础医学   252篇
口腔科学   34篇
临床医学   138篇
内科学   465篇
皮肤病学   20篇
神经病学   119篇
特种医学   47篇
外科学   350篇
综合类   9篇
预防医学   85篇
眼科学   29篇
药学   106篇
肿瘤学   294篇
  2023年   8篇
  2022年   37篇
  2021年   40篇
  2020年   34篇
  2019年   30篇
  2018年   38篇
  2017年   34篇
  2016年   24篇
  2015年   37篇
  2014年   56篇
  2013年   55篇
  2012年   90篇
  2011年   139篇
  2010年   68篇
  2009年   65篇
  2008年   102篇
  2007年   116篇
  2006年   134篇
  2005年   130篇
  2004年   106篇
  2003年   93篇
  2002年   118篇
  2001年   34篇
  2000年   38篇
  1999年   32篇
  1998年   29篇
  1997年   16篇
  1996年   23篇
  1995年   21篇
  1994年   17篇
  1993年   17篇
  1992年   20篇
  1991年   22篇
  1990年   23篇
  1989年   16篇
  1988年   16篇
  1987年   16篇
  1986年   24篇
  1985年   18篇
  1984年   13篇
  1983年   6篇
  1979年   9篇
  1978年   9篇
  1972年   8篇
  1971年   7篇
  1970年   9篇
  1969年   8篇
  1968年   11篇
  1967年   7篇
  1966年   8篇
排序方式: 共有2070条查询结果,搜索用时 109 毫秒
1.
2.
The development of new treatments for metabolic syndrome is urgent project for decreasing the prevalence of coronary heart disease and diabetes mellitus in the advanced countries. Peroxisome proliferator-activated receptor (PPAR)alpha and gamma agonists have shed light on the treatment of hypertriglyceridemia and type 2 diabetes mellitus, respectively. Among PPARs, analysis of the PPARdelta functions is lagging behind because specific PPARdelta agonists have not been developed. The appearance of new PPARdelta agonists is brightening the prospects for elucidating the physiological role of PPARdelta. PPARdelta is a new target for the treatment of metabolic syndrome. In particular, the fact that fatty acid oxidation and energy dissipation in skeletal muscle and adipose tissue by PPARdelta agonists lead to improved lipid profile, reduced adiposity and insulin sensitivity is a breakthrough. It seems that treatment of PPARdelta agonists operate similarly to the caloric restriction and prolonged exercise. We suggest that the physiological role of PPARdelta may be an indicator for switching from glucose metabolism to fatty acid metabolism. To receive new benefits of PPARdelta agonists against metabolic syndrome by increasing fatty acid consumption in skeletal muscle and adipose tissue, we need to unveil more details on the functions of PPARdelta itself and its agonists in the future.  相似文献   
3.
The three-dimensional structure of the cofactors of the reaction center of Rhodobacter sphaeroides R-26 has been determined by x-ray diffraction and refined at a resolution of 2.8 A with an R value of 26%. The main features of the structure are similar to the ones determined for Rhodopseudomonas viridis [Michel, H., Epp, O. & Deisenhofer, J. (1986) EMBO J. 5, 2445-2451]. The cofactors are arranged along two branches, which are approximately related to each other by a 2-fold symmetry axis. The structure is well suited to produce light-induced charge separation across the membrane. Most of the structural features predicted from physical and biochemical measurements are confirmed by the x-ray structure.  相似文献   
4.
OBJECTIVES: Laparoscopic surgery for kidney treatment is a common procedure. However, the efficacy of this procedure in patients with several comorbidities has not been well investigated. We conducted a retrospective comparison of results of laparoscopic surgery between patients with several comorbidities and patients with no comorbidity to access the efficacy and safety of this procedure. METHODS: The subjects were 20 patients with three or more comorbidities (group A) and 46 patients with less than three comorbidities (group B). These 66 patients were 48 men and 18 women with a mean age of 62.3 years (age range, 24-83 years). The data from these two groups were compared for American Society of Anesthesiology (ASA) physical status score, previous surgical history, duration of surgery, estimated blood loss, tumor size, complications during and after surgery, conversion rates, time to oral intake, and length of hospital stay. RESULTS: The initial ASA score and age were significantly higher for the patients with comorbidities (P < 0.0001, P = 0.0008, respectively). All other variables before, during, and after surgery were similar for both laparoscopic groups. However, the incidence of atelectasis of laparoscopy was higher than that of open surgery. CONCLUSIONS: Laparoscopic nephrectomy for patients with comorbidities is safe and minimally invasive. Further investigation to prevent atelectasis is necessary.  相似文献   
5.
Abstract:   A 66-year-old man was referred to our hospital with chest discomfort and shortness of breath. Seven months previously he had undergone a laparoscopic left nephroureterectomy for a left renal pelvic tumor and was given two cycles of adjuvant chemotherapy (methotrexate, epirubicin and cisplatin). Echocardiogram showed an 8-mm sized mass extending from the right atrium into the right ventricle. On computed tomography, multiple lung tumors, as well as the right atrial and ventricular mass, were seen. The patient died of acute heart failure caused by right ventricular outflow obstruction. On autopsy, a right atrial and ventricular metastasis of the initial transitional cell carcinoma was found. The patient's cause of death was acute heart failure as a result of cardiac metastasis of his initial renal pelvic carcinoma.  相似文献   
6.
Changes in solubility and axonal transport of tubulin during maturation and aging have been investigated using sciatic motor fibers of rats at 4, 7, 14, 30, and 80 weeks of age. One to six weeks after injection of L-[35S]methionine into the spinal cord, labeled cytoskeletal proteins in consecutive segments of the sciatic nerve and the ventral roots were fractionated into soluble and insoluble forms by extraction in 1% Triton at low temperature. In 4-week-old rats, the two forms of tubulin were transported coordinately in a single wave with the average rate of 2 mm/day. At 7 weeks of age, two components in tubulin transport were observed to develop, possibly reflecting the maturation of the axonal cytoskeleton. The slower main component (1.5 mm/day) contained most of the insoluble form together with the neurofilament proteins and the faster component (3 mm/day) was enriched in the soluble form. Though significantly different in composition, the two components correspond to slow component a (SCa) and slow component b (SCb) originally defined in the optic system. A progressive decrease in transport rates of both SCa and SCb was observed with rats at 14, 30, and 80 weeks of age. In addition, there was a large decrease in the proportion of insoluble tubulin during the course of transport in animals older than 30 weeks. This loss of the insoluble form seems to be accounted for partly by the proteolytic degradation of the severely retarded SCa proteins. Changes in axonal transport of tubulin may thus reflect age-related changes in dynamics and turnover of the axonal cytoskeleton.  相似文献   
7.
(Received for publication on Nov. 14, 1996; accepted on May 12, 1997)  相似文献   
8.
Protodioscin (PD) was purified from fenugreek (Trigonella foenumgraecum L.) and identified by Mass, and 1H- and 13C-NMR. The effects of PD on cell viability in human leukemia HL-60 and human stomach cancer KATO III cells were investigated. PD displayed strong growth inhibitory effect against HL-60 cells, but weak growth inhibitory effect on KATO III cells. Morphological change showing apoptotic bodies was observed in the HL-60 cells treated with PD, but not in KATO III cells treated with PD. Flow cytometric analysis showed that the hypodiploid nuclei of HL-60 cells were increased to 75.2, 96.3, and 100% after a 3-day treatment with 2.5, 5, and 10 microM PD, respectively. The fragmentation by PD of DNA to oligonucleosomal-sized fragments, that is a characteristic of apoptosis, was observed to be both concentration- and time-dependent in the HL-60 cells. These findings suggest that growth inhibition by PD of HL-60 cells results from the induction of apoptosis by this compound in HL-60 cells.  相似文献   
9.
The exposure of human lymphoid leukemia Molt 4B cells to sesaminol, a component of sesame oil led to both growth inhibition and the induction of apoptosis. Morphological change showing apoptotic bodies was observed in the cells treated with sesaminol. The fragmentation of DNA by sesaminol to oligonucleosomal-sized fragments that are characteristics of apoptosis was observed to be concentration- and time-dependent. These findings suggest that growth inhibition of Molt 4B cells by sesaminol results from the induction of apoptosis in the cells.  相似文献   
10.
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