全文获取类型
收费全文 | 15466篇 |
免费 | 1303篇 |
国内免费 | 28篇 |
专业分类
耳鼻咽喉 | 138篇 |
儿科学 | 483篇 |
妇产科学 | 269篇 |
基础医学 | 2167篇 |
口腔科学 | 293篇 |
临床医学 | 1811篇 |
内科学 | 2896篇 |
皮肤病学 | 416篇 |
神经病学 | 1819篇 |
特种医学 | 501篇 |
外科学 | 1552篇 |
综合类 | 195篇 |
一般理论 | 5篇 |
预防医学 | 1409篇 |
眼科学 | 386篇 |
药学 | 1191篇 |
2篇 | |
中国医学 | 37篇 |
肿瘤学 | 1227篇 |
出版年
2023年 | 88篇 |
2022年 | 157篇 |
2021年 | 316篇 |
2020年 | 198篇 |
2019年 | 322篇 |
2018年 | 344篇 |
2017年 | 264篇 |
2016年 | 284篇 |
2015年 | 327篇 |
2014年 | 418篇 |
2013年 | 631篇 |
2012年 | 908篇 |
2011年 | 927篇 |
2010年 | 537篇 |
2009年 | 445篇 |
2008年 | 789篇 |
2007年 | 766篇 |
2006年 | 790篇 |
2005年 | 767篇 |
2004年 | 710篇 |
2003年 | 656篇 |
2002年 | 621篇 |
2001年 | 398篇 |
2000年 | 366篇 |
1999年 | 330篇 |
1998年 | 144篇 |
1997年 | 138篇 |
1996年 | 131篇 |
1995年 | 86篇 |
1994年 | 105篇 |
1993年 | 102篇 |
1992年 | 238篇 |
1991年 | 241篇 |
1990年 | 246篇 |
1989年 | 229篇 |
1988年 | 249篇 |
1987年 | 208篇 |
1986年 | 219篇 |
1985年 | 222篇 |
1984年 | 141篇 |
1983年 | 156篇 |
1982年 | 100篇 |
1980年 | 85篇 |
1979年 | 127篇 |
1978年 | 115篇 |
1977年 | 84篇 |
1976年 | 86篇 |
1974年 | 82篇 |
1973年 | 86篇 |
1972年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Identification and localization of muscarinic acetylcholine receptor proteins in brain with subtype-specific antibodies 总被引:31,自引:0,他引:31
A I Levey C A Kitt W F Simonds D L Price M R Brann 《The Journal of neuroscience》1991,11(10):3218-3226
mRNAs encoding five genetically distinct muscarinic ACh receptors are present in the CNS. Because of their pharmacological similarities, it has not been possible to detect the individual encoded proteins; thus, their physiological functions are not well defined. To characterize the family of proteins, a panel of subtype-selective antibodies was generated against recombinant muscarinic receptor proteins and shown to bind specifically to each of the cloned receptors. Using immunoprecipitation, three receptor proteins (m1, m2, and m4) accounted for the vast majority of the total solubilized muscarinic binding sites in rat brain. These receptor subtypes had marked differences in regional and cellular localization as shown by immunocytochemistry. The m1-protein was present in cortex and striatum and was localized to cell bodies and neurites, consistent with its role as a major postsynaptic muscarinic receptor. The m2-receptor protein was abundant in basal forebrain, scattered striatal neurons, mesopontine tegmentum, and cranial motor nuclei; this distribution is similar to that of cholinergic neurons and suggests that m2 is an autoreceptor. However, m2 was also present in noncholinergic cortical and subcortical structures, providing evidence that this subtype may presynaptically modulate release of other neurotransmitters and/or function postsynaptically. The m4-receptor was enriched in neostriatum, olfactory tubercle, and islands of Calleja, indicating an important role in extrapyramidal function. These results clarify the roles of these genetically defined receptor proteins in cholinergic transmission in brain.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
42.
This exploratory study has examined the effect of selected characteristics on the career advancement patterns of nurse executives in service and educational settings. The findings are not consistently in agreement with those of other researchers. For example, Hall et al. found that nearly two-thirds of nursing deans had planned their careers to attain that position. In this study, however, eighty-three percent of the respondents indicated that they had not planned their career advancement, but had simply taken opportunities that had come their way. The influence of others was important in the career advancement of these administrators. Many individuals, including faculty and nursing service colleagues, nursing directors, deans, and non-nursing administrators supported the respondents' personal and professional development through role modeling, teaching skills, and encouragement. Deliberate career planning and education in administration were, for the most part, lacking. Although the sample is too small to generate general conclusions about the universe of nurse executives, this does suggest that it is not uncommon for deans and service administrators to learn necessary skills on the job. 相似文献
43.
44.
Reperfusion increases neutrophils and leukotriene B4 receptor binding in rat focal ischemia. 总被引:19,自引:0,他引:19
F C Barone D B Schmidt L M Hillegass W J Price R F White G Z Feuerstein R K Clark E V Lee D E Griswold H M Sarau 《Stroke; a journal of cerebral circulation》1992,23(9):1337-47; discussion 1347-8
BACKGROUND AND PURPOSE: Neutrophils are critically involved with ischemia and reperfusion injury in many tissues but have not been studied under conditions of reperfusion after focal cerebral ischemia. The present studies were conducted to confirm our previous observations quantifying neutrophils in rat permanent focal stroke using a myeloperoxidase activity assay and to extend them to transient ischemia with reperfusion. In addition, leukotriene B4 receptor binding in ischemic tissue was evaluated as a potential marker for inflammatory cell infiltration. METHODS: Histological, enzymatic, and receptor binding techniques were used to evaluate neutrophil infiltration and receptor binding in infarcted cortical tissue 24 hours after permanent middle cerebral artery occlusion (n = 25) or temporary occlusion for 80 (n = 12) or 160 (n = 22) minutes followed by reperfusion for 24 hours in spontaneously hypertensive rats. RESULTS: Sham surgery (n = 26) produced no changes in any parameter measured. After permanent middle cerebral artery occlusion, neutrophil accumulation was observed histologically, but the infiltration was moderate and typically within and adjacent to blood vessels bordering the infarcted cortex. After temporary middle cerebral artery occlusion with reperfusion, marked neutrophil infiltration was observed throughout the infarcted cortex. Myeloperoxidase activity was increased (p less than 0.05) after permanent occlusion and to a greater extent after temporary occlusion with reperfusion. Myeloperoxidase activity (units per gram wet weight) in ischemic cortex was increased over that in nonischemic (control) cortex 32.2-fold, 54.6-fold, and 92.1-fold for permanent occlusion and 80 and 160 minutes of temporary occlusion with reperfusion, respectively (p less than 0.05). Sham surgery produced no changes in myeloperoxidase activity. Leukotriene B4 receptor binding also was increased (p less than 0.05) after focal ischemia and paralleled the increases in myeloperoxidase activity. Ischemic cortex-specific receptor binding (femtomoles per milligram protein) was 3.87 +/- 0.63 in sham-operated rats and 4.57 +/- 0.98, 8.98 +/- 1.11, and 11.12 +/- 1.63 for rats subjected to permanent occlusion and 80 and 160 minutes of temporary occlusion with reperfusion, respectively (all p less than 0.05 different from sham-operated). Cortical myeloperoxidase activity was significantly correlated with the degree of cortical leukotriene B4 receptor binding (r = 0.66 and r = 0.79 in two different studies, p less than 0.01). CONCLUSION: These data indicate that neutrophils are involved in focal ischemia and that there is a dramatic accumulation of neutrophils in infarcted tissue during reperfusion that can be quantified using the myeloperoxidase activity assay. Leukotriene B4 receptor binding increases in infarcted tissue in a parallel manner, which suggests that the increased leukotriene B4 binding is to receptors located on the accumulating neutrophils. 相似文献
45.
Experimental liver metastasis was studied in 4-5 week old athymic nude mice that were injected intrasplenically with a human colorectal tumor cell line (LoVo). A treatment schedule combining 5-fluorouracil and interferon (IFN) was previously shown to inhibit liver metastases. When this treatment was delayed until after splenectomy at 1, 2 and 3 weeks after tumor cell injections, liver metastases were not inhibited. However, when IFN was given during the interval between tumor cell injections and splenectomy (as neoadjuvant therapy), liver metastases were inhibited in the 2 and 3 week groups, but not in the 1 week group. 相似文献
46.
Effect of vertical banded gastroplasty on the natural history of gastritis in patients with morbid obesity: a follow-up study 总被引:1,自引:0,他引:1
Vertical banded gastroplasty is an accepted surgical treatment for morbid obesity. The aim of this study was to evaluate its effect on the natural history of gastritis, as the occurrence of gastritis and dysplasia have been reported after gastric bypass, another type of bariatric surgery. Thirty-four patients who underwent vertical banded gastroplasty between 1983 and 1987 were studied, and the follow-up varied from 1 to 47 months (mean 22 months). We found no increase of gastritis and intestinal metaplasia after surgery, and we did not observe any case of gastric dysplasia. Only one patient with pre- and postoperative specimens showed a deterioration in gastric histology after surgery, and this was of a minor degree. These initial results are encouraging for surgeons interested in the treatment of morbid obesity. 相似文献
47.
Marcella R Price Donna L Bratton Mary D Klinnert 《Annals of allergy, asthma & immunology》2002,89(6):572-577
BACKGROUND: Quality of life has increased in popularity as an outcome measure in health research. However, the measurement of quality of life has been questioned on methodologic grounds, as it often shows little association with objective measures of disease status. OBJECTIVE: For this report we studied the determinants of pediatric asthma caregiver report of quality of life and its relationship to disease burden. METHOD: Ninety-eight children who were admitted to a Pediatric Day Program for an asthma evaluation were enrolled in an outcome study. A complete set of medical records for the 2-year period before and after the admission was collected and systematically coded for health care utilization. Using the Pediatric Asthma Caregiver's Quality of Life Questionnaire, data were collected at baseline, discharge, and year after the admission. Caregiver negative affect (anxiety and depression), measured with the Brief Symptom Inventory, was also collected at baseline and discharge. RESULTS: Caregiver report of quality of life was unrelated to health care utilization at baseline but instead was significantly related to baseline caregiver negative affect. A significant relationship between health care utilization and quality of life was present at followup. The Emotional Function scale from the quality of life measure can account for most of the relationship between quality of life and negative affect. CONCLUSIONS: Caregiver affect may have a considerable influence on report of quality of life. Understanding the individual characteristics of the respondent is important when using a quality of life instrument as an outcome measure. 相似文献
48.
49.
R A Price K Lunetta R Ness M A Charles M F Saad E Ravussin P H Bennett D J Pettitt W C Knowler 《International journal of obesity (2005)》1992,16(11):851-857
We examined distribution characteristics of the body mass index (BMI; weight/height; kg/m2) in a sample of 1128 male and 1372 female Pima Indians aged 15-65 years. We found that women had a higher mean and variance of BMI than men. From commingling analyses, we determined that the distribution of BMI could be accounted for either by a single skewed distribution or by a mixture of multiple normal components. These component distributions may be used to define provisional thresholds in selecting families for genetic studies. To ensure genetic segregation of obesity predisposing genes in Pima families will require that some members have BMIs > or = 40 kg/m2. 相似文献
50.
Nighttime bracing for adolescent idiopathic scoliosis with the Charleston bending brace. Preliminary report 总被引:5,自引:0,他引:5
The authors report their preliminary experience with the Charleston bending brace for the treatment of adolescent idiopathic scoliosis. This brace holds the patient in the position of maximum side bend correction and is worn only at night. Patients in this prospective multicentered study met all the following criteria: skeletal immaturity (Risser 0, 1+, or 2+), curvature greater than 25 degrees before bracing, no prior treatment, and greater than 1-year follow-up since initiation of treatment. There were 191 structural curves in the 139 patients. One hundred fifteen patients (83%) showed improvement or less than 5 degree change in curvature. Twenty-four patients (17%) demonstrated an increase in curvature greater than 5 degrees. Based on these preliminary results, continued use of bending brace treatment at nighttime only is justified for adolescent idiopathic scoliosis. Patients with double curves should be observed closely for increase in compensatory curves. 相似文献