全文获取类型
收费全文 | 6791篇 |
免费 | 664篇 |
国内免费 | 55篇 |
专业分类
耳鼻咽喉 | 77篇 |
儿科学 | 254篇 |
妇产科学 | 113篇 |
基础医学 | 865篇 |
口腔科学 | 136篇 |
临床医学 | 820篇 |
内科学 | 1457篇 |
皮肤病学 | 56篇 |
神经病学 | 668篇 |
特种医学 | 348篇 |
外科学 | 1031篇 |
综合类 | 133篇 |
一般理论 | 3篇 |
预防医学 | 457篇 |
眼科学 | 186篇 |
药学 | 558篇 |
1篇 | |
中国医学 | 6篇 |
肿瘤学 | 341篇 |
出版年
2021年 | 127篇 |
2020年 | 70篇 |
2019年 | 93篇 |
2018年 | 101篇 |
2017年 | 122篇 |
2016年 | 112篇 |
2015年 | 97篇 |
2014年 | 185篇 |
2013年 | 235篇 |
2012年 | 276篇 |
2011年 | 276篇 |
2010年 | 190篇 |
2009年 | 218篇 |
2008年 | 247篇 |
2007年 | 275篇 |
2006年 | 277篇 |
2005年 | 259篇 |
2004年 | 208篇 |
2003年 | 187篇 |
2002年 | 170篇 |
2001年 | 186篇 |
2000年 | 194篇 |
1999年 | 145篇 |
1998年 | 129篇 |
1997年 | 108篇 |
1996年 | 107篇 |
1995年 | 91篇 |
1994年 | 87篇 |
1993年 | 91篇 |
1992年 | 172篇 |
1991年 | 138篇 |
1990年 | 177篇 |
1989年 | 158篇 |
1988年 | 158篇 |
1987年 | 151篇 |
1986年 | 148篇 |
1985年 | 142篇 |
1984年 | 110篇 |
1983年 | 99篇 |
1982年 | 68篇 |
1981年 | 60篇 |
1980年 | 61篇 |
1979年 | 91篇 |
1978年 | 90篇 |
1977年 | 85篇 |
1976年 | 74篇 |
1975年 | 62篇 |
1974年 | 83篇 |
1973年 | 79篇 |
1970年 | 56篇 |
排序方式: 共有7510条查询结果,搜索用时 15 毫秒
11.
Stephen D. Scoggin M.D. Richard C. Frazee M.D. Samuel K. Snyder M.D. John C. Hendricks M.D. John W. Roberts M.D. Richard E. Symmonds M.D. Randall W. Smith M.D. 《Diseases of the colon and rectum》1993,36(8):747-750
The use of laparoscopic surgical techniques is now being applied to a variety of operations traditionally performed in an open fashion. Twenty patients underwent laparoscopic-guided large and small bowel surgery at our institution from March 1991 to April 1992. The indications for surgery included polyps, obstruction, bleeding, and perforation, and pathologic diagnoses included benign polyps, lipomas, inflammatory bowel disease, perforation of a jejunal diverticulum, colonic arteriovenous malformations, and adenocarcinoma. Mobilization of the colon, ligation of the mesentery, and closure of the mesenteric defect were performed using the laparoscopic equipment. One trocar site was enlarged to 3 cm to deliver the bowel through the abdominal wall. All anastomoses were hand-sewn. Postoperative hospitalization ranged from 2 to 31 days (median, five days). No mortality was noted, and morbidity was 20 percent. We conclude that laparoscopic-guided bowel surgery is technically feasible and should translate into shorter hospitalization and less patient discomfort. 相似文献
12.
13.
In this study, the word retrieval, phonological awareness, sentence completion, and narrative discourse processing skills of 93 reading-disabled and 93 normally achieving subjects from 8 to 14 years of age were compared. The subjects were matched for age, sex, and neighborhood. Results revealed that the two groups differed significantly on the time and accuracy of word retrieval, their ability to produce a syntactically appropriate structure in a sentence completion task, their retelling of stories that had been read to them, their answers to questions about the stories, and their inferences. Further analysis revealed that the variance in the younger reading-disabled children's reading comprehension scores was best accounted for by their performance on the sentence completion and word retrieval measures; the inferencing skills of the older reading-disabled children best accounted for the variance in their reading comprehension. By contrast, the younger normally achieving children's reading comprehension scores were best accounted for by their sentence completion, the proportion of the stories that they retold, and word retrieval scores. The proportion of stories retold and the phonological awareness score of the older normally achieving children best accounted for the variance in their reading scores. These findings suggest that the oral language skills of normally achieving and reading-disabled children may relate differently to their reading comprehension at different age levels. 相似文献
14.
Caloric restriction (CR) extends life span and retards the onset of physiological changes and pathologies associated with aging, but the underlying mechanisms remain unresolved. This study demonstrates that CR postpones the documented age-related declines in and/or enhances the activity and microsomal concentration of several liver monooxygenases in male rats, i.e., NADPH cytochrome P-450 reductase, total cytochromes P-450. However, the relative concentration of cytochrome P-450b+C did not exhibit statistically significant changes, whereas another isozyme, the male specific P-450h, declined significantly in both ad libitum-fed and CR rats as a function of increasing age. While CR appears to retard age-associated changes in certain liver enzymes, this effect is by no means universal. The hepatic monooxygenases constitute a well-characterized enzyme system in which to examine the perturbation of the aging process by CR. 相似文献
15.
MR imaging of cerebral dural sinus thrombosis 总被引:1,自引:0,他引:1
16.
R Snyder J Bishop G Brodie W Burns A Coates J Levi D Raghavan M Schwarz M Tattersall D Thomson 《Cancer treatment reports》1987,71(3):273-276
Epirubicin was studied in a phase I setting to find the maximum tolerated dose when given weekly for 3 of 4 weeks. Forty-one evaluable patients were treated in groups at doses increasing from 20 to 45 mg/m2. The highest dose level produced the maximum degree of myelosuppression (lowest neutrophil count, 1.9 X 10(9)/L; range, 0-3.7) recorded on Day 22. This was well-tolerated in this group of mainly pretreated patients. Nonhematologic side effects were minimal. This dose schedule allows a greater dose per unit time to be administered than other recommended schedules for epirubicin. 相似文献
17.
J M Snyder H F Rodgers J A O'Brien N Mahli S A Magliato P L Durham 《The Anatomical record》1992,232(1):133-140
Maternal administration of glucocorticoids is known to stimulate fetal lung maturation. In the present study, we used microscopy and stereology to evaluate the morphological effects of maternal glucocorticoid treatment on rabbit fetal lung tissue. Betamethasone was administered to pregnant rabbits on days 25 and 26 of gestation at a dose of 0.2 mg/kg body weight. The animals were sacrificed on day 27 of gestation. Glucocorticoid treatment significantly increased the presumptive airspace in the fetal lung tissue but did not alter the relative proportion of epithelium, connective tissue, or vasculature in the tissue. In addition, glucocorticoid treatment significantly increased the proportion of type II cells in the prealveolar epithelium, increased the rate of phosphatidylcholine synthesis, and increased the content of the major surfactant-associated protein, SP-A, in the fetal lung tissue. We could detect no effect of betamethasone on lamellar body cross-sectional area, numerical density, or volume density within fetal lung type II cells. Glucocorticoid treatment of the pregnant doe caused a decrease in the volume density of intracellular glycogen and an increase in the volume density of mitochondria in fetal lung type II cells. Betamethasone treatment did not alter the distance between fetal lung epithelial cells and subadjacent connective tissue cells. However, glucocorticoid treatment increased the number of connective tissue foot processes that pierced the epithelial basal lamina. Thus, glucocorticoid treatment of the pregnant doe results in structural changes in the fetal lung tissue, an acceleration of some aspects of type II cell differentiation, and a concomitant increase in epithelial-mesenchymal interactions. 相似文献
18.
H W Snyder J H Bertram D H Henry D D Kiprov W B Benny A Mittelman G L Messerschmidt S K Cochran W Perkins J P Balint 《AIDS (London, England)》1991,5(10):1257-1260
Thirty-seven HIV-infected homosexual men with thrombocytopenia (less than 100 x 10(9)/l) received protein A immunoadsorption treatments to remove platelet-sensitizing immunoglobulin (Ig) G and circulating immune complexes (CIC) from plasma. Patients received an average of six treatments each, consisting of 250 ml plasma over a 3-week period. Clinical improvement in hemorrhagic symptoms associated with substantial increase in platelet counts was achieved in 18 patients. These responses were maintained over a median follow-up period of more than 7 months in 14 evaluable patients who were not lost to follow-up (three patients relapsed in 2 weeks and one received another therapy). Generally, moderate transient treatment-related side-effects included fever, musculoskeletal pain, chills and nausea. A transient serum sickness-like reaction was observed in seven patients, leading to termination of treatment in two. Clinical responses were associated with significant decreases in levels of platelet-sensitizing Ig, including CIC. Stimulation of broadly cross-reactive anti-antigen-binding fragment [F(ab)2], antibodies contributed to these responses. Protein A immunoadsorption is an effective alternative treatment for HIV-associated thrombocytopenia. 相似文献
19.
Use of triple-lumen subclavian catheters for administration of total parenteral nutrition. 总被引:1,自引:0,他引:1
N Clark-Christoff V A Watters W Sparks P Snyder J P Grant 《JPEN. Journal of parenteral and enteral nutrition》1992,16(5):403-407
This study evaluated the safety of triple vs single-lumen catheters in intravenous nutrition. Patients who were judged likely to benefit from a triple-lumen catheter were randomized to receive either a single-lumen catheter, with additional peripheral or central venous access as needed, or a triple-lumen catheter. All patients were at increased risk of catheter-related infection because of one or more of the following conditions: > 60 years of age, breakdown of skin integrity, severe underlying illness, diagnosis of acute pancreatitis, recent head or neck surgery, or presence of a preexisting infection. Patients were excluded who had neutropenia, were immunosuppressed, had body burns > 40%, or had contaminated wounds in the subclavicular area. Of 204 patients entered between June 1989 and November 1991, 177 completed the required > or = 7 days of therapy. Seventy-eight of these patients were randomized to a single-lumen catheter and 99 to a triple-lumen catheter. Catheters were inserted and maintained by the Nutrition Support Team. Dressings were monitored daily and changed weekly using a bio-occlusive dressing. When parameters were met for a possible septic episode, simultaneous peripheral and central catheter blood cultures were obtained using the Isolator method. Catheter-related sepsis was considered present if the colony count from a central catheter lumen was > or = 5 times that of the peripheral blood. The incidence of catheter-related sepsis for single-lumen catheters was 2.6% (2 of 78) compared with 13.1% for triple-lumen catheters (13 of 99) (p < .01). No correlation was found with the number of insertion attempts, catheter days, or patient's age.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
20.
John D Snyder 《Acta paediatrica (Oslo, Norway : 1992)》1992,81(S383):78-81
Although the causes of persistent diarrhea are largely unknown, dietary protein sensitivity has been identified as one possible mechanism. Since nutritional therapy appears to be an essential component of treatment for persistent diarrhea, a clearer understanding of the importance of dietary protein allergy is needed to provide optimal dietary recommendations. This paper reviews the current concepts of the pathophysiology, clinical features and criteria for diagnosis of dietary protein sensitivity. Evaluation of the results of several clinical studies indicates that dietary protein sensitivity does occur especially in young infants fed cows'milk but that it is an uncommon event, especially in older infants and children. 相似文献