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   4845篇
  免费   296篇
  国内免费   19篇
耳鼻咽喉   43篇
儿科学   151篇
妇产科学   67篇
基础医学   530篇
口腔科学   72篇
临床医学   353篇
内科学   1229篇
皮肤病学   49篇
神经病学   339篇
特种医学   153篇
外科学   1025篇
综合类   21篇
预防医学   71篇
眼科学   354篇
药学   261篇
中国医学   4篇
肿瘤学   438篇
  2023年   37篇
  2022年   64篇
  2021年   135篇
  2020年   70篇
  2019年   93篇
  2018年   124篇
  2017年   96篇
  2016年   109篇
  2015年   102篇
  2014年   164篇
  2013年   174篇
  2012年   285篇
  2011年   316篇
  2010年   173篇
  2009年   168篇
  2008年   275篇
  2007年   263篇
  2006年   256篇
  2005年   253篇
  2004年   245篇
  2003年   226篇
  2002年   220篇
  2001年   117篇
  2000年   131篇
  1999年   91篇
  1998年   45篇
  1997年   47篇
  1996年   43篇
  1995年   32篇
  1994年   38篇
  1993年   22篇
  1992年   55篇
  1991年   62篇
  1990年   54篇
  1989年   49篇
  1988年   45篇
  1987年   48篇
  1986年   37篇
  1985年   59篇
  1984年   37篇
  1983年   34篇
  1982年   16篇
  1979年   17篇
  1978年   17篇
  1975年   14篇
  1973年   21篇
  1972年   13篇
  1971年   32篇
  1970年   19篇
  1968年   18篇
排序方式: 共有5160条查询结果,搜索用时 31 毫秒
1.
2.
This cross-sectional study was conducted to examine whether the obstructive sleep apnea syndrome (OSAS) is associated with elevation of the pulse wave velocity (PWV) and increase in the plasma levels of C-reactive protein (CRP), both of which are known markers of cardiovascular risk, and also to determine if the concurrent presence of the metabolic syndrome might exacerbate this elevation in the levels of these cardiovascular risk markers in subjects with OSAS. With these objectives, the PWV and serum CRP were measured in 184 subjects attending a sleep clinic. It was found that the PWV and CRP were higher in the subjects with OSAS (n=94) than in those without OSAS (n=90). Furthermore, among the subjects with OSAS, the PWV and CRP were higher in those with the concurrent presence of the metabolic syndrome (n= 41; PWV=1,562+/-19 cm/s; CRP=1.8+/-0.2 mg/l) than in those without metabolic syndrome (n=53; PWV=1,432+/-21 cm/s; CRP=1.2+/-0.1 mg/l) (p<0.05). A general linear model analysis demonstrated that OSAS and metabolic syndrome were independently associated with elevated PWV and increase of the plasma levels of CRP. OSAS appears to be associated with increased cardiovascular risk, as reflected by both elevated PWV and increase of the plasma CRP. The concurrent presence of metabolic syndrome may exacerbate this increase in cardiovascular risk in subjects with OSAS. Therefore, the concurrent presence of metabolic syndrome may constitute an additive cardiovascular risk factor in subjects with OSAS.  相似文献   
3.
4.
The biochemical activities of 8 lysosomal acid hydrolases in leukemic cells from 48 patients were examined. Characteristic alterations were found in α-mannosidase, β-galactosidase and N-acetyl-β-glucosaminidase activities of leukemic cells. The level of α-mannosidase activity was much higher in myelo(mono)genous leukemias (AML, AMoL, AMMoL, CML and CMMoL) than in lymphogenous ones (ALL, T-cell leukemia, hairy cell leukemia and CLL) without exception. The β-galactosidase activity also differed as a result of α-mannosidase, except in T-cell leukemia. In T-cell leukemia it was within the range of normal lymphocytes, but in the other lymphogenous leukemias it was significantly below normal. N-acetyl-β-glucosaminidase activity in myelo(mono)genous leukemic cells was above the range of normal granulocytes. The changes in these enzyme levels were consistent. The lymphocytic or myelocytic nature of three cases of acute undifferentiated leukemia could be determined by enzyme studies. In two cases it was lymphocytic and in one it was myelocytic. The enzymatic abnormalities were also found in morphologically mature neutrophils from patients with not only chronic types (CML, CMMoL) but also acute types (AMoL, AMMoL) of leukemias, and were similar to those of their respective leukemic cells. Analysis of lysosomal enzymes (at least three of those mentioned above), can elucidate one of the biochemical properties of leukemic cells and may be valuable in the differentiation of leukemias.  相似文献   
5.
PURPOSE: The purpose of this study was to investigate the effects of chewing and clenching on salivary cortisol levels as an indicator of stress. MATERIALS AND METHODS: Seventeen healthy dentulous subjects were given arithmetic exercises to perform within a 20-minute time limit in order to elicit stress (stress loading). In the first experiment (chewing), after stress loading, the subjects were asked to chew a paraffin wax while reading printed material (books, magazines, etc.) in silence for 10 minutes. The same procedure was then carried out again for control purposes, but this time the subjects were not required to chew wax. In the second experiment (light clenching), after stress loading, the subjects were required to carry out 5 seconds of light clenching followed by 5 seconds of rest repeatedly over a 3-minute period. The whole 3-minute process was repeated a total of three times. The control data for this second experiment consisted of measurements taken during the rest periods. Saliva specimens were collected in both experiments both before stress loading and after each procedure during 1-minute intervals to measure cortisol levels. RESULTS: In the chewing experiment, salivary cortisol levels were significantly reduced by chewing, compared with those in the controls (p < 0.05). This reduction in salivary cortisol was observed during chewing over a 10-minute period following stress loading. In the clenching experiment, salivary cortisol levels also showed a significant reduction during clenching, compared with those in the controls (p < 0.05). CONCLUSIONS: These results suggest that chewing and clenching promote relaxation in subjects under stress.  相似文献   
6.
The requirement for endoscopic access to a stricture is a major limitation of the endoscopic dilatation for the treatment of strictures in the gastrointestinal tract. We have developed the double‐balloon enteroscopy method that enables visualization of the entire small bowel. In addition, double‐balloon enteroscopy has a potential for the interventional therapy including dilatation of strictures. We present here a case of jejunal strictures in a 47‐year‐old woman with Crohn's disease successfully treated with a balloon catheter in combination with double‐balloon enteroscopy. Balloon dilation with double‐balloon enteroscopy is a promising method for the treatment of small bowel strictures in Crohn's disease.  相似文献   
7.
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   
8.
We evaluated nitric oxide induction in antitumor therapy consisting of anti–CD3 monoclonal antibody (anti–CD3) and interleukin–2 (IL–2), then determined the effect of nitric oxide reduction with L–NG–monomethyl arginine (LNMA) on the therapeutic methods. Female C57BL/6 mice, MCA102 (a non immunogenic, NK–resistant murine fibrosarcoma cell line), and 145–2C11 (hamster anti–murine–CD3 mAb) were utilized in an experimental hepatic metastasis model developed by injecting a tumor cell suspension into the spleen of mice. A marked increase in serum NO2+ NO1 was observed at 19 hours after anti–CD3 (10 μ, IV) and additional IL–2 administrations (40times101 U, twice, If) induced a further increase. The NO2, + NO3- elevation in spot urine in the combination therapy was not suppressed with LNMA at a dose of 100 μg/h but was significantly lowered at 300 μg/h. The efficacy of the anti–CD3 + IL–2 therapy was not diminished by LNMA administration either at 100 μg/h or at 300 μg/h.  相似文献   
9.
We successfully replanted five amputated legs in five patients and followed the patients for two years or more (average, six years and three months). Although some patients found it impossible to squat and to run because of joint contractures, muscle weakness, or deformities of the foot, all patients could perform other activities without difficulty. None had important pain or any intolerance to cold, and all were satisfied with the results of the replantation.  相似文献   
10.
We previously selected a group of hypertension candidate genes by a key word search using the OMIM database of NCBI and validated 525 coding single nucleotide polymorphisms (SNPs) in 179 hypertension candidate genes by DNA sequencing in a Japanese population. In the present study, we examined the association between 61 non-synonymous SNPs and blood pressure variations and hypertension. We used DNA samples taken from 1,880 subjects in the Suita study, a population-based study using randomly selected subjects. Analyses of covariance adjusting for age, body mass index, hyperlipidemia, diabetes, smoking, drinking, and antihypertensive medication revealed that 17 polymorphisms in 16 genes (APOB, CAST, CLCNKB, CTNS, GHR, GYS1, HF1, IKBKAP, KCNJ11, LIPC, LPL, P2RY2, PON2, SLC4A1, TRH, VWF) were significantly associated with blood pressure variations. Multivariate logistic regression analysis with adjustment for the same factors revealed that 11 polymorphisms in 11 genes (CAST, CTLA4, F5, GC, GHR, LIPC, PLA2G7, SLC4A1, SLCI8A1, TRH, VWF) showed significant associations with hypertension. Five polymorphisms in five genes, CAST(calpastatin), LIPC (hepatic lipase), SLC4A1 (band 3 anion transporter), TRH (thyrotropin-releasing hormone), and VWF (von Willebrand factor), were significantly associated with both blood pressure variation and hypertension. Thus, our study suggests that these five genes were susceptibility genes for essential hypertension in this Japanese population.  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