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   1491篇
  免费   140篇
  国内免费   3篇
耳鼻咽喉   43篇
儿科学   26篇
妇产科学   24篇
基础医学   171篇
口腔科学   25篇
临床医学   162篇
内科学   330篇
皮肤病学   28篇
神经病学   60篇
特种医学   39篇
外科学   245篇
综合类   27篇
预防医学   73篇
眼科学   77篇
药学   127篇
中国医学   10篇
肿瘤学   167篇
  2023年   13篇
  2022年   56篇
  2021年   109篇
  2020年   55篇
  2019年   63篇
  2018年   87篇
  2017年   62篇
  2016年   65篇
  2015年   59篇
  2014年   70篇
  2013年   67篇
  2012年   121篇
  2011年   101篇
  2010年   59篇
  2009年   55篇
  2008年   71篇
  2007年   73篇
  2006年   59篇
  2005年   56篇
  2004年   57篇
  2003年   55篇
  2002年   44篇
  2001年   31篇
  2000年   7篇
  1999年   12篇
  1998年   13篇
  1997年   8篇
  1996年   7篇
  1995年   3篇
  1994年   2篇
  1993年   4篇
  1992年   10篇
  1991年   7篇
  1990年   6篇
  1989年   5篇
  1987年   7篇
  1986年   2篇
  1985年   6篇
  1984年   3篇
  1980年   5篇
  1979年   3篇
  1978年   3篇
  1976年   3篇
  1974年   2篇
  1972年   2篇
  1967年   2篇
  1966年   5篇
  1964年   2篇
  1963年   2篇
  1961年   2篇
排序方式: 共有1634条查询结果,搜索用时 15 毫秒
1.
Understanding why persons with human immunodeficiency virus (HIV) have accelerated atherosclerosis and its sequelae, including coronary artery disease (CAD) and myocardial infarction, is necessary to provide appropriate care to a large and aging population with HIV. In this review, we delineate the diverse pathophysiologies underlying HIV-associated CAD and discuss how these are implicated in the clinical manifestations of CAD among persons with HIV. Several factors contribute to HIV-associated CAD, with chronic inflammation and immune activation likely representing the primary drivers. Increased monocyte activation, inflammation, and hyperlipidemia present in chronic HIV infection also mirror the pathophysiology of plaque rupture. Furthermore, mechanisms central to plaque erosion, such as activation of toll-like receptor 2 and formation of neutrophil extracellular traps, are also abundant in HIV. In addition to inflammation and immune activation in general, persons with HIV have a higher prevalence than uninfected persons of traditional cardiovascular risk factors, including dyslipidemia, hypertension, insulin resistance, and tobacco use. Antiretroviral therapies, although clearly necessary for HIV treatment and survival, have had varied effects on CAD, but newer generation regimens have reduced cardiovascular toxicities. From a clinical standpoint, this mix of risk factors is implicated in earlier CAD among persons with HIV than uninfected persons; whether the distribution and underlying plaque content of CAD for persons with HIV differs considerably from uninfected persons has not been definitively studied. Furthermore, the role of cardiovascular risk estimators in HIV remains unclear, as does the role of traditional and emerging therapies; no trials of CAD therapies powered to detect clinical events have been completed among persons with HIV.  相似文献   
2.
A 2,5-pyrrolidinedione linked nitrogen mustard derivative, (R,S)3-[N,N-bis(2-chloroethyl)]-amino-1-(2'-methoxyphenyl)pyrrolidine- 2,5-dione hydrochloride (I) showed a marked antiproliferative effect on mouse Sarcoma 180. Since (I) is also active against L1210 and P388 leukaemias, its toxicity in mice was evaluated. A study of acute toxicity revealed focal liver cell necrosis. Another derivative, (R,S)3-[N,N-bis-(2-chloroethyl)]amino-1-(4'-n-butoxyphenyl)pyrrolidine- 2,5-dione dihydrate (II), which also possessed significant anticancer effect on P388 and L1210 leukaemias, was inactive against Sarcoma 180.  相似文献   
3.
We employ diffuse optical tomography (DOT) to track treatment progress in a female subject presenting with locally advanced invasive carcinoma of the breast during neoadjuvant chemotherapy. Three-dimensional images of total hemoglobin concentration and scattering identified the tumor. Our measurements reveal tumor shrinkage during the course of chemotherapy, in reasonable agreement with magnetic resonance images of the same subject. A decrease in total hemoglobin concentration contrast between tumor and normal tissue was also observed over time. The results demonstrate the potential of DOT for measuring physiological parameters of breast lesions during chemotherapy.  相似文献   
4.
Hemagglutinin activity (HA) was studied in the midgut extracts from highly (h) and lowly susceptible strains of Aedes aegypti mosquitoes to Dengue-2 virus (DEN-2). HA in the midgut extracts from these two isofemale strains of mosquitoes was high in as compared to (h) mosquitoes. HA was found to be higher with chicken red blood cells (RBCs) than with rabbit and human RBCs of O group. Larval midgut extracts showed higher activity than those from adult female mosquitoes. Exposure of midgut extracts to 100 degrees C for 10 mins destroyed the activity. The activity was observed between pH 6 and pH 10. HA in midgut extracts was also studied using twenty different carbohydrates; five of them showed an inhibition of HA. The inhibitory carbohydrates, when incorporated into DEN-2-infected bloodmeal, showed a reduction in the susceptibility of mosquitoes to the virus as compared to the control ones fed on the virus alone. Similarly, when these carbohydrates were incorporated in the DEN-2-infected inoculum, the inoculated mosquitoes showed a reduction in the susceptibility to the virus. HA in the virus-infected midgut extracts was higher than that in the uninfected controls. These results suggest that the presence of HA in the midgut may be one of the factors that affect the susceptibility of Ae. aegypti mosquitoes to DEN-2.  相似文献   
5.
OBJECTIVE: To evaluate the association between Mycoplasma genitalium, Chlamydia trachomatis, and pelvic inflammatory disease (PID) METHODS: A case-control methodology was used. Swab eluates were processed using the QIAamp DNA mini kit. Polymerase chain reaction (PCR) for M genitalium was carried out using a real time in-house 16S based assay. An endocervical swab was taken and tested for the presence of C trachomatis (ligase chain reaction, Abbott Laboratories), and a high vaginal swab was taken and tested for the presence of Neisseria gonorrhoeae and bacterial vaginosis. RESULTS: Of the PID cases 13% (6/45) had evidence of M genitalium infection compared to none of the controls (0/37); 27% (12/45) of the cases had C trachomatis infection compared to none of the controls; and 16% (7/45) of cases only had serological evidence of C trachomatis infection compared to 5% (2/37) of controls. Cases were more likely to present with M genitalium and/or C trachomatis than controls (p<0.001). CONCLUSIONS: This study indicates that there may be an association between M genitalium and PID, and that this relation is largely independent of C trachomatis. Future studies need to investigate the pathological basis of the relation between M genitalium and PID using samples from women with PID diagnosed using laparoscopy and endometrial biopsy. Little is known about the epidemiology of M genitalium: large scale epidemiological investigations are needed to determine the prevalence, incidence, and factors associated with this emerging infection.  相似文献   
6.
The ability of Amphotericin B ('Fungizone') to alter the natural resistance of leukemia L1210 to vincristine was studied in BDF1 mice Neither Fungizone nor the "solubilizing agent" sodium deoxycholate, when used in combination with vincristine potentiated the activity of the drug against L1210. There was no change in the activity pattern of 5-fluorouracil against L1210 or vincristine against P388 lymphocytic leukemia respectively, which are sensitive to these drugs. Thus, both Fungizone and sodium deoxycholate failed to improve the activity of the drugs in either a naturally resistant or sensitive murine leukemia in vivo.  相似文献   
7.
8.
Tracheoesophageal fistula is a life threatening condition. Patients not managed surgically ultimately die of their disease. Surgical management is the treatment of choice. We present a case of a patient that developed a tracheoesophageal fistula after tracheostomy. Surgical repair was done which failed due to infection. The patient was managed with the help of an esophageal stent and Trichloroacetic Acid cautery. This approach can be used in selected patients, depending upon the size and site of TEE Larger fistulae and those situated lower down e.g. supra carinal cannot be managed by this technique.  相似文献   
9.
PURPOSE: To monitor tumor blood flow noninvasively during photodynamic therapy (PDT) and to correlate flow responses with therapeutic efficacy. EXPERIMENTAL DESIGN: Diffuse correlation spectroscopy (DCS) was used to measure blood flow continuously in radiation-induced fibrosarcoma murine tumors during Photofrin (5 mg/kg)/PDT (75 mW/cm2, 135 J/cm2). Relative blood flow (rBF; i.e., normalized to preillumination values) was compared with tumor perfusion as determined by power Doppler ultrasound and was correlated with treatment durability, defined as the time of tumor growth to a volume of 400 mm3. Broadband diffuse reflectance spectroscopy concurrently quantified tumor hemoglobin oxygen saturation (SO2). RESULTS: DCS and power Doppler ultrasound measured similar flow decreases in animals treated with identical protocols. DCS measurement of rBF during PDT revealed a series of PDT-induced peaks and declines dominated by an initial steep increase (average +/- SE: 168.1 +/- 39.5%) and subsequent decrease (59.2 +/- 29.1%). The duration (interval time; range, 2.2-15.6 minutes) and slope (flow reduction rate; range, 4.4 -45.8% minute(-1)) of the decrease correlated significantly (P = 0.0001 and 0.0002, r2= 0.79 and 0.67, respectively) with treatment durability. A positive, significant (P = 0.016, r2= 0.50) association between interval time and time-to-400 mm3 was also detected in animals with depressed pre-PDT blood flow due to hydralazine administration. At 3 hours after PDT, rBF and SO2 were predictive (P < or = 0.015) of treatment durability. CONCLUSION: These data suggest a role for DCS in real-time monitoring of PDT vascular response as an indicator of treatment efficacy.  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