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   1331篇
  免费   291篇
  国内免费   19篇
耳鼻咽喉   26篇
儿科学   29篇
妇产科学   48篇
基础医学   377篇
口腔科学   61篇
临床医学   254篇
内科学   337篇
皮肤病学   6篇
神经病学   102篇
特种医学   49篇
外科学   128篇
综合类   20篇
预防医学   61篇
眼科学   11篇
药学   61篇
肿瘤学   71篇
  2021年   12篇
  2019年   13篇
  2018年   13篇
  2017年   10篇
  2016年   13篇
  2015年   22篇
  2014年   22篇
  2013年   36篇
  2012年   36篇
  2011年   41篇
  2010年   37篇
  2009年   37篇
  2008年   34篇
  2007年   59篇
  2006年   63篇
  2005年   27篇
  2004年   41篇
  2003年   44篇
  2002年   42篇
  2001年   57篇
  2000年   51篇
  1999年   53篇
  1998年   36篇
  1997年   41篇
  1996年   39篇
  1995年   33篇
  1994年   44篇
  1993年   21篇
  1992年   58篇
  1991年   45篇
  1990年   43篇
  1989年   53篇
  1988年   34篇
  1987年   39篇
  1986年   36篇
  1985年   51篇
  1984年   27篇
  1983年   22篇
  1982年   15篇
  1981年   15篇
  1980年   12篇
  1979年   23篇
  1977年   9篇
  1975年   12篇
  1974年   16篇
  1973年   14篇
  1971年   16篇
  1970年   11篇
  1969年   11篇
  1966年   9篇
排序方式: 共有1641条查询结果,搜索用时 15 毫秒
1.
A 27-year-old man was admitted with high fever and shivers eleven days after returning from vacation in Indonesia. Physical examination, laboratory values, abdominal ultrasound, and chest x-ray were not conclusive. All blood cultures yielded growth of Salmonella enterica serovar Typhi, and typhoid fever was diagnosed. Subsequently, the patient developed septic shock and pulmonary edema.In this case report epidemiological, clinical, and therapeutic aspects of typhoid fever are discussed with special emphasis on criteria for severe typhoid fever, which is treated with additional glucocorticoids.  相似文献   
2.
Anxiety disorders and anxiety symptoms are highly prevalent in the general population and more so in the medically ill. They have a number of negative consequences for these patients and may worsen the outcome of the medical illness and increase health care utilization. In the evaluation of these patients, it is of paramount importance to identify the etiology of the anxiety and, in particular, to differentiate primary from secondary anxiety. Management includes medications (especially benzodiazepines and selective serotonin reuptake inhibitors) and psychotherapy (particularly cognitive-behavioral therapy).  相似文献   
3.
The present study explored the role of murine monocyte chemotactic protein (MCP) in the T cell-mediated hypersensitive granulomatous response to Schistosoma mansoni eggs. The study examined the time course of local production, contribution to cellular infiltration, and the role of T cells in endogenous regulation. Synchronized pulmonary granulomas were induced under conditions of primary and secondary states of immunity. Primer-directed polymerase chain reaction analysis showed increased MCP mRNA expression in granulomatous lungs, mainly in the secondary response. Levels of MCP were measured by enzyme-linked immunosorbent assay in cultures of intact granulomas. Spontaneous MCP production was modest in primary granuloma cultures, reaching a maximum of 5.7 +/- 0.9 ng/ml by 16 days. In contrast, the secondary response showed augmented and accelerated production, achieving 13 +/- 2.0 ng/ml by 2 days. Immunohistochemical staining revealed the strongest MCP expression within microvascular adventitial cells or pericytes as well as in scattered mononuclear cells associated with granulomas. Staining was not detected in normal lungs. Passive immunization with anti-MCP-1 antibodies caused a 40% reduction in the secondary granuloma area but did not significantly affect the primary response. With adoptive cell transfer and T cell subset depletion, it was shown that Thy-1+ and CD5+ cells augmented, whereas CD8+ cells appeared to impair, MCP production. This provides direct evidence that MCP is involved in secondary Th2-mediated response to schistosome eggs and is subject to regulation by T cells.  相似文献   
4.
We have investigated the role of basal insulin concentration on leucine kinetics (determined by means of 1-[13C]leucine) and energy metabolism (determined by indirect calorimetry) in eight septic patients by reducing insulin (and glucagon) secretion by somatostatin infusion. Basal glucagon concentration was elevated (744 +/- 381 pg/mL), and insulin concentration was normal (10 +/- 4 microU/mL). Basal resting energy expenditure (REE) was 151 +/- 8% that of predicted basal energy expenditure, and leucine appearance (Ra), oxidation, and nonoxidative disposal rates were all elevated above the normal ranges. Somatostatin infusion reduced insulin concentration by 52% and glucagon concentration by 64%. This resulted in a significant increase in the rate of leucine oxidation from 0.96 +/- 0.08 to 1.18 +/- 0.14 mumol/kg/min (p less than 0.01), and nonoxidative leucine disposal decreased from 2.95 +/- 0.18 to 2.67 +/- 0.17 mumol/kg/min (p less than 0.01). Somatostatin infusion also caused significant increases in REE and fat oxidation from 1310 +/- 100 to 1505 +/- 128 kcal/m2/day (p less than 0.05) and from 1.72 +/- 0.24 to 2.41 +/- 0.41 mg/kg/min, respectively, and a slight decrease of carbohydrate oxidation from 1.51 +/- 0.49 to 1.31 +/- 0.49 mg/kg/min. These metabolic responses can be attributed to the reduction in insulin concentration, because they are in the opposite direction of changes that would occur as a consequence of a reduction in glucagon concentration. We conclude that the basal insulin plays an important role in attenuating net protein loss and energy expenditure.  相似文献   
5.
6.
Acquired circulating anticoagulants.   总被引:2,自引:0,他引:2  
Acquired inhibitors of blood coagulation, which are pathologic circulating substances that directly inhibit clotting factors or their reactions, most commonly occur in patients with hereditary bleeding disorders. This article contains a discussion of acquired circulating anticoagulants that arise de novo in patients with previously normal hemostatic mechanisms. Pathogenesis and management are also discussed. Treatment of these patients poses a challenge for the hematologist because, unlike hereditary hemophiliacs who have learned to adjust their lifestyle, the acquired hemophiliac is unprepared for hemorrhagic episodes.  相似文献   
7.
Summary A 3-year-old boy developed several subcutaneous nodular lesions on his right arm. Based on the histological examination of one of these nodules furunculosis was suspected and cefuroxime was tentatively given. However, acid-fast bacilli were then detected in the tissue specimen and a few colonies of acid fast, gram-positive rods grew on blood agar. Definitive species diagnosis (Mycobacterium marinum) was rapidly achieved by automated sequencing of amplified 16S-rDNA and antimicrobial therapy was adjusted according to the available literature. After 3 weeks of treatment with clarithromycin, rifampicin and protionamid regression of the nodular lesions was evident.
Infektion der oberen Extremität durchMycobacterium marinum — Diagnose mit Hilfe von 16S-rDNA Analyse
Zusammenfassung Wir berichten von einem 3-jährigen Jungen, der verschiedene subkutane Knoten im rechten Arm entwickelte. Nach histologischer Untersuchung wurde zunächst der Verdacht auf Furunkulose geäußert und eine vorläufige Therapie mit Cefuroxim begonnen. Es wurden dann jedoch säurefeste Stäbchen im entnommenen Gewebe nachgewiesen und eine Woche später auf Blutagar grampositive, säurefeste Stäbchen angezüchtet. Die definitive Speziesdiagnose (Mycobacterium marinum) wurde rasch mit automatischer 16S-rDNA Sequenzbestimmung erzielt und die Therapie entsprechend der verfügbaren Literatur korrigiert. Nach drei Wochen einer Behandlung mit Clarithromycin, Rifampicin und Protionamid war ein Rückgang der subkutanen Knoten erkennbar.
  相似文献   
8.
Absorptiometric, histomorphometric, and chemical analyses of bones from growing rats fed diets with low (0.2%, w/w), marginal (0.4%, w/w), or adequate (0.8%, w/w) calcium (Ca) content with or without phytate were compared. Phytate was added to each diet in a molar ratio of 19:1 to calcium. Male weanling Sprague-Dawley rats were fed one of the six diets for 8 weeks. At the end of 8 weeks, rats were killed, and mandibles, femurs, and tibias were removed. Bone density profiles were determined on the mandibles and femurs using single photon absorptiometry. Femurs were also used for calcium and phosphorus analyses. Tibias were used for histomorphometric analyses. Bone density of the femurs and mandibles increased as dietary Ca increased. The only effect of phytate addition measured was in the 0.8% calcium diet, where density was lower in rats fed the phytate-containing 0.8% calcium diet. Femur calcium concentration also increased as dietary Ca increased and was unaffected by addition of phytate. Femur phosphorus concentration was unaffected by dietary Ca levels but was increased by 10% when phytate was added to the diet. Bone density values were highly correlated with bone calcium and phosphorus levels (r = 0.94). Rats fed the 0.2% calcium diets had 20% lower mineralized bone area and 20% larger medullary cavity area than rats fed the other diets. Bone densitometry appears to be useful for determining changes in bone occurring in growing rats fed low, marginal, and adequate levels of dietary Ca. Bone density values also correlated well with chemically determined calcium and phosphorus concentrations and with histomorphometric data.  相似文献   
9.
BACKGROUND: Developments in accelerator mass spectrometry (AMS) now permit the determination of femtogram amounts of 26Al in blood and in various tissues with good precision and free of external contamination. METHODS: In the present study we used trace quantities of 26Al to investigate the intestinal absorption and compartmentalization of aluminium in rats with renal failure (Nx, 5/6 nephrectomy) and in pair- fed controls (C). Single oral doses of 20 ng 26Al were administered to six animals in each group and, subsequently, 24-h post-load 26Al was analysed in serum, urine, bone, liver, and spleen by means of AMS. RESULTS: Serum concentrations of 26Al were significantly lower in uraemic rats compared to controls, whereas urinary excretion was comparable (Nx, 7.11 +/- 5.78 pg/day vs C, 9.46 +/- 6.10 pg/day), suggesting a higher fraction of ultrafiltrable serum 26Al in uraemia. The target tissues of cellular transferrin-mediated 26Al uptake, liver and spleen, tended to show a larger degree of aluminium accumulation in controls (0.26 +/- 0.31 pg/g vs Nx, 0.14 +/- 0.10 pg/g and 0.37 +/- 0.27 pg/g vs Nx, 0.25 +/- 0.27 pg/g respectively). In contrast, in bone, a site of extracellular aluminium deposition, 26Al concentrations were more elevated in uraemia (1.22 +/- 0.59 pg/g vs C: 0.68 +/- 0.30 pg/g). Estimated total 26Al accumulation in all measured target tissues was significantly higher in uraemic rats (28.15 +/- 9.90 pg vs C: 17.03 +/- 7.03 pg) and total recovery of 26Al from tissue and urine was 26.58 +/- 6.74 pg in controls and 35.75 +/- 7.03 pg in uraemic animals, suggesting a fractional absorption of 0.133% and 0.175% respectively. CONCLUSIONS: Our data suggest that fractional absorption from a dietary level dose of 26Al is about 0.13%. Compartmentalization occurs in transferrin-dependent target tissues such as liver and spleen; however, in quantitative terms extracellular deposition in bone is more important. Uraemia has a significant effect on the intestinal absorption and compartmentalization of aluminium. It enhances fractional absorption and increases subsequent extracellular deposition of aluminium in bone. However, at the same time uraemia does not increase transferrin-dependent cellular accumulation of aluminium in liver and spleen.   相似文献   
10.
To evaluate the role of the dialysate in the stimulation of interleukin-1 (IL-1) production during clinical hemodialysis (HD), we studied maintenance HD patients in two experiments. Cellulosic hollow-fiber dialyzers were obtained after 20 minutes of HD using either nonsterile standard dialysate (n = 6) or sterile pyrogen free 0.9% saline as dialysate (n = 6). After rinsing the blood compartment with normal saline, dialyzers were incubated at 37 degrees C for six hours. Aliquots from the blood compartment were analyzed for the presence of IL-1 by (1) rabbit pyrogenic response after intravenous injection or (2) thymocyte co-proliferation assay. The in vivo assay showed a significantly greater febrile response when standard dialysate was used than in the sterile saline group (P less than .001), and this response could be abolished by heat inactivation of aliquots (P less than .001). The in vitro assay confirmed the presence of significantly greater amounts of IL-1 (P less than .05). Studies were repeated using filter sterilized standard dialysate (n = 6) v standard dialysate (n = 6) for 240 minutes of clinical HD. The in vitro assay revealed significantly lower IL-1 levels in the filtered sterilized dialysate group (P less than .05), however, a blank control assay showed yet significantly lower levels (P less than .05). We conclude that IL-1 is produced during clinical HD and that endotoxin or its fragments play a role in the stimulation of IL-1 production, probably through monocytes adhering to the dialysis membrane. In addition to this dialysate factor, IL-1 production appears also to be stimulated by a blood-membrane interaction.  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