全文获取类型
收费全文 | 4444篇 |
免费 | 355篇 |
国内免费 | 18篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 163篇 |
妇产科学 | 132篇 |
基础医学 | 589篇 |
口腔科学 | 60篇 |
临床医学 | 522篇 |
内科学 | 641篇 |
皮肤病学 | 53篇 |
神经病学 | 249篇 |
特种医学 | 163篇 |
外国民族医学 | 1篇 |
外科学 | 798篇 |
综合类 | 106篇 |
一般理论 | 3篇 |
预防医学 | 542篇 |
眼科学 | 96篇 |
药学 | 246篇 |
中国医学 | 2篇 |
肿瘤学 | 439篇 |
出版年
2021年 | 69篇 |
2020年 | 38篇 |
2019年 | 64篇 |
2018年 | 65篇 |
2017年 | 53篇 |
2016年 | 42篇 |
2015年 | 74篇 |
2014年 | 97篇 |
2013年 | 137篇 |
2012年 | 185篇 |
2011年 | 187篇 |
2010年 | 128篇 |
2009年 | 85篇 |
2008年 | 192篇 |
2007年 | 184篇 |
2006年 | 173篇 |
2005年 | 189篇 |
2004年 | 172篇 |
2003年 | 187篇 |
2002年 | 147篇 |
2001年 | 196篇 |
2000年 | 163篇 |
1999年 | 125篇 |
1998年 | 50篇 |
1997年 | 51篇 |
1996年 | 53篇 |
1995年 | 48篇 |
1994年 | 43篇 |
1992年 | 95篇 |
1991年 | 116篇 |
1990年 | 102篇 |
1989年 | 81篇 |
1988年 | 91篇 |
1987年 | 92篇 |
1986年 | 75篇 |
1985年 | 79篇 |
1984年 | 65篇 |
1983年 | 52篇 |
1982年 | 45篇 |
1981年 | 31篇 |
1980年 | 34篇 |
1979年 | 67篇 |
1978年 | 34篇 |
1977年 | 48篇 |
1976年 | 34篇 |
1975年 | 41篇 |
1974年 | 44篇 |
1973年 | 32篇 |
1972年 | 37篇 |
1971年 | 32篇 |
排序方式: 共有4817条查询结果,搜索用时 15 毫秒
41.
Three groups of 8 first year grazing calves each were either left untreated as controls (group 1), or were treated with 10 mg levamisole spot-on/kg bodyweight (group 2) or with 0.5 mg ivermectin pour-on/kg bodyweight 3, 8, and 13 weeks after turnout (group 3), respectively. Egg counts, herbage larval counts, worm counts of tracer calves, pepsinogen concentrations and weight gains showed a high efficacy of the strategic treatment in group 3 against gastrointestinal nematodes. The calves of group 1 and 2 developed clinical signs of parasitic bronchitis whereas the group 3 animals remained clinically healthy. The strategic treatment with ivermectin cleaned the respective pasture from infective lungworm larvae. 相似文献
42.
Interleukin-1 activation of vascular endothelium. Effects on procoagulant activity and leukocyte adhesion. 总被引:20,自引:9,他引:20 下载免费PDF全文
M. P. Bevilacqua J. S. Pober M. E. Wheeler R. S. Cotran M. A. Gimbrone Jr 《The American journal of pathology》1985,121(3):394-403
Interleukin-1 (IL-1), an inflammatory/immune mediator, acts directly and selectively on cultured human vascular endothelial cells to alter two important functional properties. First, IL-1 induces endothelial cell biosynthesis and surface expression of a tissue factor-like procoagulant activity. Second, IL-1 dramatically increases the adhesiveness of the endothelial cell surface for human peripheral blood polymorphonuclear leukocytes (6-42-fold increase) and monocytes (2-5-fold increase), as well as the related leukocyte cell lines HL-60 and U937. These IL-1 effects are concentration-dependent (maximum, 5-10 U/ml), time-dependent (peak 4-6 hours), and reversible. Cycloheximide and actinomycin D block these IL-1 actions on endothelium, which suggests the requirement for de novo protein synthesis. Human-monocyte-derived IL-1, cell-line--derived IL-1, and recombinant IL-1 exhibited comparable biologic activities in our assays, whereas two other mediators, IL-2 and immune interferon, were without effect. IL-1 stimulated procoagulant activity and leukocyte adhesion in human endothelial cells cultured from both umbilical veins and adult saphenous veins but not in other cultured cell types, including SV-40-transformed human endothelial cells and human dermal fibroblasts. Similar actions of IL-1 on vascular endothelium in vivo may contribute to the development of intravascular coagulation and enhanced leukocyte--vessel wall adhesion at sites of inflammation. 相似文献
43.
The neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive neurodegenerative diseases of childhood. CLN6, the gene mutated in variant late infantile NCL (vLINCL), was recently cloned. We report the identification of eight further mutations in CLN6 making a total of 18 reported mutations. These mutations include missense, nonsense, small deletions or insertions, and two splice-site mutations. Ten mutations affect single amino acids, all of which are conserved across vertebrate species. Minor differences in the pattern of disease symptom evolution can be identified. One patient with a more protracted disease progression was a compound heterozygote for a missense mutation and an unidentified mutation. Fifteen CLN6 mutations occur in one or two families only, and families from the same country do not all share the same mutation. Unlike NCLs caused by mutations in CLN1, CLN3, CLN5, and CLN8, there is no major founder mutation in CLN6. However, one mutation (E72X) is significantly more common in patients from Costa Rica than two other mutations present in that same population. In addition, a 1-bp insertion (c.316insC) is associated with families from Pakistan and I154del may be common in Portugal. A group of Roma Gypsy families from the Czech Republic share two disease-associated haplotypes, one of which is also present in a Pakistani family, consistent with the proposed migration of the Roma from the Indian subcontinent 1,000 years ago. All mutations are recorded in the NCL Mutation Database together with their country of origin for use in the development of rapid screening assays to confirm diagnosis and to facilitate carrier testing appropriate to a population. 相似文献
44.
Cystadenoma with mesenchymal stroma (CMS) in the liver and bile ducts. A clinicopathologic study of 17 cases, 4 with malignant change 总被引:9,自引:0,他引:9
This study of 17 cases describes a homogeneous clinicopathologic group of tumors previously subsumed under the general term, hepatobiliary cystadenoma. This unique group of neoplasms that the authors have termed "cystadenoma with mesenchymal stroma" (CMS), occurred exclusively in women and showed two essential tumor components: a cyst lining of columnar to cuboidal, mucin secreting epithelium; and a moderately to densely cellular stroma composed of spindle (rarely oval) cells. The stromal element appeared similar to primitive mesenchyme, both on light and electron microscopic study, showing variable differentiation toward fibroblasts, smooth muscle, adipose tissue and capillaries. Cases of hepatobiliary "cystadenoma" in the literature with histology similar to CMS had similar sex and age incidences, while histologically dissimilar cases, lacking the mesenchymal stroma, had significantly different parameters. Four cases of CMS in this series showed malignant change that was manifested as papillary adenocarcinoma, suggesting the need for complete surgical removal of these premalignant neoplasms. 相似文献
45.
Exchange lists: revised 1986 总被引:2,自引:1,他引:1
M J Franz P Barr H Holler M A Powers M L Wheeler J Wylie-Rosett 《Journal of the American Dietetic Association》1987,87(1):28-34
A committee composed of members of The American Dietetic Association and the American Diabetes Association has revised Exchange List for Meal Planning. Changes were made, as deemed necessary, on the basis of nutritional recommendations for persons with diabetes as understood in 1986. Major changes include rewriting the text to make it more useful in the education of persons with diabetes; changing the order of the exchange lists to emphasize a high-carbohydrate, high-fiber diet, as well as to better reflect the order of foods in menu planning; adding symbols to foods high in fiber and sodium; changing nutritive values for the starch/bread and fruit lists; adding lists of combination foods, free foods, and foods recommended only for occasional use; developing a data base; and initiating a plan for field testing and evaluation. The committee also developed a simplified meal planning tool, Healthy Food Choices, to be used for initial or "survival" level education. In poster format, foods are grouped by calories into six food groups. Approximate portion sizes of commonly used foods are listed. Blank lines are provided for the nutrition counselor to write in a suggested menu or meal plan for the client. Because the booklet does not use the word "diabetes" specifically, it is appropriate as a general teaching tool. 相似文献
46.
Infectious mononucleosis can be disabling to athletes of all ages. Traditionally, long periods of limited physical activity are prescribed. During this time period a significant level of detraining can occur. Sixteen cadets from USMA who were identified as having mononucleosis had their aerobic capacity determined immediately after becoming afebrile. Nine of these cadets then entered a 2-week exercise program while the others remained inactive. After this time period all cadets were allowed to exercise at their own discretion. After an additional 2-week period (4 weeks after becoming afebrile), aerobic capacity was again determined. There were no differences within the groups when comparing VO2 max, METS, or run time to exhaustion on the two aerobic tests. One individual served as a case study with aerobic tests every week for 4 weeks and then 6 months after becoming afebrile. Again, no differences were observed in any variables measured. Thus, prolonged bed rest does not seem to be indicated for the individual recovering from mononucleosis. Noncontact activities can be initiated as soon as the fever disappears. J Orthop Sports Phys Ther 1986;8(4):199-202. 相似文献
47.
The department of radiology at New England Deaconess Hospital, in response to the recently imposed legislative constraints on reimbursement for the care of hospitalized patients, has extended a method developed in 1977 to define staffing requirements and productivity and to track departmental operating efficiency. 相似文献
48.
49.
Courtney Pisano Renata Fabia Junxin Shi Krista Wheeler Sheila Giles Lisa Puett Dylan Stewart Susan Ziegfeld Jennifer Flint Jenna Miller Pablo Aguayo Emily C. Alberto Randall S. Burd Lisa Vitale Justin Klein Rajan K. Thakkar 《Burns : journal of the International Society for Burn Injuries》2021,47(3):545-550
BackgroundAccurate resuscitation of pediatric patients with large thermal injury is critical to achieving optimal outcomes. The goal of this project was to describe the degree of variability in resuscitation guidelines among pediatric burn centers and the impact on fluid estimates.MethodsFive pediatric burn centers in the Pediatric Injury Quality Improvement Collaborative (PIQIC) contributed data from patients with ≥15% total body surface area (TBSA) burns treated from 2014 to 2018. Each center's resuscitation guidelines and guidelines from the American Burn Association were used to calculate estimated 24-h fluid requirements and compare these values to the actual fluid received.ResultsDifferences in the TBSA burn at which fluid resuscitation was initiated, coefficients related to the Parkland formula, criteria to initiate dextrose containing fluids, and urine output goals were observed. Three of the five centers’ resuscitation guidelines produced statistically significant lower mean fluid estimates when compared with the actual mean fluid received for all patients across centers (4.53 versus 6.35 ml/kg/% TBSA, p < 0.001), (4.90 versus 6.35 ml/kg/TBSA, p = 0.002) and (3.38 versus 6.35 ml/kg/TBSA, p < 0.0001).ConclusionsThis variation in practice patterns led to statistically significant differences in fluid estimates. One center chose to modify its resuscitation guidelines at the conclusion of this study. 相似文献