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   8294篇
  免费   666篇
  国内免费   20篇
耳鼻咽喉   100篇
儿科学   178篇
妇产科学   250篇
基础医学   1217篇
口腔科学   195篇
临床医学   843篇
内科学   1624篇
皮肤病学   191篇
神经病学   800篇
特种医学   327篇
外科学   1153篇
综合类   61篇
一般理论   3篇
预防医学   599篇
眼科学   217篇
药学   763篇
中国医学   20篇
肿瘤学   439篇
  2023年   66篇
  2022年   81篇
  2021年   170篇
  2020年   128篇
  2019年   162篇
  2018年   195篇
  2017年   154篇
  2016年   166篇
  2015年   172篇
  2014年   220篇
  2013年   371篇
  2012年   430篇
  2011年   408篇
  2010年   261篇
  2009年   211篇
  2008年   339篇
  2007年   372篇
  2006年   356篇
  2005年   311篇
  2004年   338篇
  2003年   311篇
  2002年   311篇
  2001年   254篇
  2000年   249篇
  1999年   202篇
  1998年   92篇
  1997年   74篇
  1995年   77篇
  1994年   67篇
  1993年   56篇
  1992年   172篇
  1991年   198篇
  1990年   158篇
  1989年   149篇
  1988年   144篇
  1987年   155篇
  1986年   137篇
  1985年   142篇
  1984年   113篇
  1983年   94篇
  1982年   67篇
  1981年   47篇
  1980年   52篇
  1979年   111篇
  1978年   75篇
  1977年   63篇
  1976年   56篇
  1975年   48篇
  1974年   48篇
  1973年   45篇
排序方式: 共有8980条查询结果,搜索用时 15 毫秒
91.
An autoradiographic method combined with a rosette technique was used to assess the bactericidal activity of individual control and inflammatory peritoneal macrophages (PM phi) in the presence or absence of expression of Fc receptor for IgG (FcR). There was a lack of FcR reactivity in a certain percentage of both categories of PM phi exposed to E. coli X43, a bacterium which is readily phagocytosed in the presence of specific antibody. Both rosetting and non-rosetting PM phi were capable of phagocytosing E. coli X43, but inflammatory PM phi showed a marked reduction in their capacity to ingest these bacteria compared with control PM phi. Once ingested the E. coli X43 were killed equally well by non-rosetting and rosetting control and inflammatory PM phi.  相似文献   
92.
OBJECTIVE: Ospemifene, a novel selective estrogen receptor modulator (SERM), shows promise for bone preservation in postmenopausal women. This study examined the effects of ospemifene on different vascular surrogate markers. DESIGN: A double-blinded study was conducted in 160 healthy, postmenopausal women who used, in a randomized order, ospemifene (at daily doses of 30, 60, or 90 mg) or placebo for 3 months. RESULTS: Although ospemifene caused falls from basal levels in total cholesterol, low-density lipoprotein cholesterol, oxidized low-density lipoprotein cholesterol, and a rise in high-density lipoprotein cholesterol, the only statistically significant difference between ospemifene and placebo was an increase of triglyceride levels (11.3%) in the 90-mg group. Ospemifene caused no significant effect on endothelial markers or homocysteine. Of the markers reflecting coagulation and fibrinolysis, plasma fibrinogen was significantly reduced in the 60- and 90-mg groups of ospemifene (8.7% and 8.5%, respectively) when compared with the placebo group. No changes were seen in generation of thrombin or degradation of crosslinked fibrin D-dimer. The uterine or carotid arteries and 24-h ambulatory blood pressure were not affected by ospemifene. Ospemifene caused no changes in basal insulin or in a 2-h glucose tolerance test, suggesting unaltered insulin sensitivity. CONCLUSIONS: Neutral effects of short-term use of ospemifene on vascular surrogate markers imply no effect for ospemifene on the risk for cardiovascular disorders in healthy, postmenopausal women.  相似文献   
93.
The DNA content of single villous cell nuclei in 14 normal pregnancies and 21 androgenetic moles with a 46,XX karyotype was measured by flow cytometry. Six molar specimens showed a low mean DNA content close to that of normal villi, whereas, 15 specimens were characterized by a high mean DNA content due to a large fraction of nuclei in the triploid to tetraploid region. The latter group presumably corresponds to the previously described "type II" moles in which the DNA pattern resembled the pattern seen in invasive moles and choriocarcinoma.  相似文献   
94.
Gold thioglucose (GTG) has been known to be an obesity causing agent for over 40 years. GTG works by affecting dendrites in the mouse ventromedial hypothalamus (VMH) producing a permanent VMH lesion and subsequent hyperphagia and obesity. We have investigated the effect of beta-thioglucose (BTG), a glucose antimetabolite, on GTG-induced lesions in the VMH of mice. Twenty-eight female CF-1 mice were used in this study. Seven micron sections were made of the mouse VMH, mounted on glass slides, and stained with hematoxylin and eosin. A previous report of BTG action on GTG-induced lesions has not supported a competitive inhibition between these two drugs. Our data demonstrate that at 1/2 hour, 6 hours, and 12 hours post BTG, BTG completely inhibited GTG-induced lesions in the VMH.  相似文献   
95.
Chromogenic substrate (CS) assay of heparin may be performed with or without addition of antithrombin (AT) to the test plasma. Both types of assay are used for monitoring of heparin therapy, reflecting either heparin activity (heparin act), or heparin concentration (heparin conc) when AT is added. In plasma samples from 43 patients treated with intravenous heparin for DVT, the ratio between heparin act and heparin conc varied from 0.36 in patients with AT plasma concentration below 0.50 U/ml, to 0.85 in patients with AT above 1.00 U/ml (mean ratio 0.61). A formula expressing heparin act as a function of AT and heparin concentration in the test plasmas of the patients was used to calculate heparin act of the total material comprising 280 patients. Mean heparin act and heparin conc were both significantly correlated to clinical outcomes (bleeding complications, pulmonary embolism and phlebography score). For monitoring heparin therapy, guidelines for plasma heparin activity or concentration ("therapeutic ranges") are requested. When using a heparin act assay, the heparin dose needed in patients with low plasma AT concentration to reach a fixed therapeutic range, may imply undue risk of bleeding. On the other hand, when a heparin conc assay indicate plasma heparin conc within therapeutic range, antithrombotic activity may still be inadequate in patients with low plasma AT concentration.  相似文献   
96.
A blind study comparing abdominal ultrasound and cystoscopy was carried out in 186 patients. 20 bladder tumours sized from 2 to 5 mm were overlooked. Combination with urine cytology increased the diagnostic sensitivity. In order to reduce costs and patient inconvenience in the bladder tumour control population abdominal ultrasound and urine cytology is advocated as an alternative to cystoscopy. This control modality seems safe in patients with "low-risk" bladder tumour disease.  相似文献   
97.
98.

Asian American immigrant (AAI) women may have suboptimal 24-h activity patterns due to traditional gender role and caregiving responsibilities. However, little is known about their objectively-measured activity. We measured AAI women’s 24-h activity patterns using accelerometry and examined cultural correlates of time in sedentary behavior (SB), light intensity physical activity (LIPA), moderate-to-vigorous physical activity (MVPA) and sleep. Seventy-five AAI women completed surveys on acculturation (years of U.S. residency and English proficiency), discrimination, and sleep quality, and 7 days of wrist- and hip-accelerometer monitoring. Linear regression was conducted controlling for age, BMI, and education. We also compared activity patterns across Asian subgroups (East, Southeast, South Asians). On average, AAI women had 33 min of MVPA, 6.1 h of LIPA, 10 h of SB, and 5.3 h of sleep per day. South Asian women had the longest SB and the shortest sleep and MVPA hours. English proficiency was negatively related to MVPA (p?=?0.03) and LIPA (p?<?0.01). Years of U.S. residency was positively related to SB (p?=?0.07). Discrimination was related to shorter (p?=?0.03) and poorer quality sleep (p?=?0.06). Culturally-tailored programs targeting SB and sleep and integrating coping strategies against discrimination could help optimize AAI women’s 24-h activity patterns.

  相似文献   
99.
BackgroundIncisional hernias (IH) following a laparotomy, on average, occur in 10–20% of patients, however, little is known about its molecular basis. Thus, a better understanding of the molecular mechanisms could lead to the identification of key target(s) to intervene pre-and post-operatively.MethodsWe examined the current literature describing the molecular mechanisms of IH and overlap these factors with smoking, abdominal aortic aneurysm, obesity, diabetes mellitus, and diverticulitis.ResultsThe expression levels of collagen I and III, matrix metalloproteinases, and tissue inhibitors of metalloproteases are abnormal in the extracellular matrix (ECM) of IH patients and ECM disorganization has an overlap with these comorbid conditions.ConclusionUnderstanding the pathophysiology of IH development and associated risk factors will allow physicians to identify patients that may be at increased risk for IH and to possibly act preemptively to decrease the incidence of IH.  相似文献   
100.
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