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   82848篇
  免费   8331篇
  国内免费   163篇
耳鼻咽喉   1180篇
儿科学   2530篇
妇产科学   1789篇
基础医学   11865篇
口腔科学   2008篇
临床医学   10191篇
内科学   14601篇
皮肤病学   1296篇
神经病学   6731篇
特种医学   2882篇
外国民族医学   10篇
外科学   11413篇
综合类   1666篇
一般理论   67篇
预防医学   9462篇
眼科学   1854篇
药学   6769篇
  1篇
中国医学   79篇
肿瘤学   4948篇
  2021年   1113篇
  2020年   740篇
  2019年   1118篇
  2018年   1393篇
  2017年   1002篇
  2016年   1093篇
  2015年   1243篇
  2014年   1636篇
  2013年   2571篇
  2012年   3469篇
  2011年   3747篇
  2010年   1990篇
  2009年   1918篇
  2008年   3229篇
  2007年   3544篇
  2006年   3418篇
  2005年   3482篇
  2004年   3251篇
  2003年   3025篇
  2002年   2959篇
  2001年   2717篇
  2000年   2829篇
  1999年   2509篇
  1998年   1097篇
  1997年   926篇
  1996年   899篇
  1995年   805篇
  1994年   836篇
  1993年   757篇
  1992年   2104篇
  1991年   2028篇
  1990年   1895篇
  1989年   1871篇
  1988年   1782篇
  1987年   1789篇
  1986年   1697篇
  1985年   1679篇
  1984年   1393篇
  1983年   1260篇
  1982年   846篇
  1981年   719篇
  1980年   641篇
  1979年   1212篇
  1978年   877篇
  1977年   766篇
  1976年   718篇
  1975年   718篇
  1974年   859篇
  1973年   752篇
  1972年   733篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
The talar beak is a well-described secondary sign of talocalcaneal coalition but is not pathognomonic of the condition and may be seen in other causes of restricted or abnormal subtalar motion. We present an unusual complication of talar beaks in two patients who sustained fractures through their beaks. One of the patients described did not have a talocalcaneal coalition but had developed a beak following a compound fracture dislocation of the ankle joint complicated by infection, a previously undescribed predisposing cause.  相似文献   
122.
Bradley  F; Morgan  S; Smith  H; Mant  D 《Family practice》1997,14(3):220-226
OBJECTIVE: We aimed to assess general practice care for patients following a myocardial infarction (MI). METHOD: A structured review was carried out of general practice records of patients identified from hospital administration data. A total of 266 survivors following MI were identified from the discharge data of 13 hospitals in Southern England and registered with 71 GPs belonging to the Wessex Research Network. Median time since hospital discharge was 2.1 years. The main outcome measures were the provision of appropriate preventive care, including cardiac rehabilitation, drug therapy, and lifestyle advice for modifiable risk factors. RESULTS: Basic care was provided to nearly all patients; 253 (95.1%, 95% Cl 91.8-97.4) had blood pressure documented after their MI, 216 of 234 patients eligible for aspirin (92.3%; 88.1-95.4) had been recommended treatment, and the provision of advice on smoking cessation was documented for 27 of 33 continuing smokers (81.8%; 64.5-93.0). However, only 73 of 236 patients eligible to attend a structured rehabilitation programme (30.9%; 25.0-36.8) were documented as having received rehabilitation. Of 89 patients with heart failure following MI, 33 (37.1%; 27.1-48.0) had no record of having been offered treatment with an ACE inhibitor. Total cholesterol measurement was documented for only 144 patients (54.1%; 48.1-60.1). We estimate that there is still the potential to prevent between 4 and 9 deaths in this group of 266 surviving patients in the next 2 years by further improving the quality of follow-up care. CONCLUSIONS: Preventive care in patients with proven ischaemic heart disease in general practice remains haphazard, even among doctors enthusiastic to participate in research and to audit their quality of care. As general practitioners we should ensure that we are providing high quality preventive care to patients with clinical disease before we focus on the even more demanding task of primary prevention.   相似文献   
123.
Background: Patients who suffer with gastroesophageal reflux Disease (GERD) endure a worsening of symptoms as their weight increases. When medical treatment of this condition in the morbidly obese patients fails, surgical intervention may be indicated. Choosing a procedure which not only helps achieve weight control but which also relieves symptoms and complications of GERD is the goal. We present a review of patients who have undergone Roux-en-Y Gastric Bypass (RYGBP) and related procedures for this disease. Methods: One hundred eighty-eight patients undergoing surgery for morbid obesity and for GERD in 1992-1996 were contacted by mail or phone. All of these patients had undergone preoperative esophagogastroduodenoscopy to grade the severity of their disease. Their preoperative symptoms were compared to those experienced postoperatively. Results: One hundred thirty patients underwent a RYGBP with modified Hill fundopexy, 22 patients underwent a distal gastrectomy with modified Hill fundopexy, 8 patients underwent distal gastrectomy alone and 28 patients underwent RYGBP alone. There have been no deaths. There were nine surgical complications, eight early and one at 2.5 years postoperation. Follow-up is 4-48 months. The average BMI dropped from 43 to 30.2 kg/m2. Whereas all patients were on some form of medical therapy before surgery, only 14 reported the need for medication postoperatively. Conclusions: Surgical intervention for weight control and treatment of GERD has been highly successful in our experience both with respect to weight control and to the reduction of reflux symptoms. Depending upon endoscopic and operative findings a RYGBP with or without an antireflux procedure can provide dramatic improvement. Gastrectomy with antireflux modifications is appropriate in selected cases.  相似文献   
124.
Cobb's collar or Moormann's ring is a stricture of the bulbar urethra which is largely unrecognised but has considerable relevance urologically as the site of congenital or post-instrumental strictures. The history, anatomy, embryology and surgical importance are reported.  相似文献   
125.
The yellow color of atherosclerotic plaque is due to the presence of carotenoids, which absorb light between 430–530 nm and account for the preferential ablation of plaque by the pulsed dye laser operating at 480 nm. This study was designed to examine tissue uptake of β-carotene and the effect of uptake on arterial plaque ablation. Forty-two atherosclerotic NZW rabbits were given intravenous β-carotene at a dose of 40 mg/kg, twice weekly and killed between 1 hour and 28 days after the initial injection. β-carotene was not detected in control specimens but was significantly greater in plaque than in normal wall at all time points following β-carotene injection (P < 0.04 Mann Whitney U test). The ablation threshold was significantly lower in β-carotene treated plaque than in untreated plaque or normal arterial wall (P < 0.01, Fisher's exact test). In this model β-carotene is preferentially taken up into arterial plaque, resulting in increased absorption of laser radiation at 480 nm and enhanced tissue ablation. © 1993 Wiley-Liss, Inc.  相似文献   
126.
Cellular toxicity and cellular carcinogenesis are closely linked. In the kidney, this relationship has been emphasized by the recent discovery of a number of putatively non-mutagenic chemicals that result in acute and chronic toxicity and ultimately in carcinogenesis, especially in the male rat. Many, but not all such compounds, result in renal PTE phagolysosomal overload. At the same time, known metabolites of other carcinogens, e.g., HCBD and FBPA, result in acute renal injury and/or necrosis, followed by chronic tubular disease, interstitial nephritis, and ultimately carcinogenesis. A series of cell mechanisms have been suggested that lead from acute cell injury to altered control of cell division. These mechanisms appear to involve ion deregulation, (especially [Ca2+]i) resulting from a variety of continued injuries, (e.g., oxidative stress from inflammatory cells) and ultimately leading to altered gene expression.  相似文献   
127.
With estimates as high as 1.8 million individuals infected with human immunodeficiency virus (HIV) in the United States, the majority asymptomatic, it is crucial that all physicians routinely use adequate disinfection procedures for medical instruments. The protosigmoidoscopic disinfection procedures used by US family physicians were evaluated for adequacy in inactivating HIV. Sixty-seven percent of 1,585 randomly selected American Academy of Family Physicians members completed a mail survey regarding these procedures. Comparing procedures used with those recommended by the Centers for Disease Control or documented to inactivate HIV, 32.4 percent were judged to be appropriate procedures; 54.4 percent of the procedures were not tested or recommended; and 13.2 percent used appropriate solutions but at inadequate concentrations or exposure times. Therefore, a substantial proportion of US family physicians performing endoscopic procedures use disinfection procedures that may not inactivate HIV. The ever-increasing prevalence of HIV demands that standardized adequate disinfection procedures be implemented by all physicians to prevent the potential nosocomial spread of HIV.  相似文献   
128.
Abstract. Objectives:To describe the outcomes of a mass carbon monoxide (CO) intoxication, and to calculate the CO half-life in a pediatric school-aged population.
Methods:A retrospective chart review was performed based on Regional Poison Center database information, hospital laboratory data, and medical records of the pediatric patients who sought care at one of 3 St. Louis area hospitals, after exposure to high levels of CO. Exposures occurred on January 5, 1996, after evidence of a CO leak was discovered at an area elementary school. Charts were reviewed for major demographics, symptoms reported, carboxyhemoglobin (COHb) levels and times, and level of effect.
Results:Information about 177 (35%) of the 504 children in attendance at school that day was available. Mean age was 8.7 ± 1.8 years (range 4–12 years). Symptoms were present in 155 (88%) of the 177 children for whom data were available. Initial COHb levels were obtained for 147 (83.1%) of the 177 children. First mean COHb level was 7.0% (95% CI = 6.6–7.5%). Second COHb level was obtained for 26 children with a mean of 2.7% (95% CI = 2.2–3.2%). Calculated half-life of COHb, on 100% 02 at 1 atm, was 44.0 minutes (95% CI = 39.6–48.2 minutes).
Conclusion:Some children had symptoms at COHb levels that traditionally have been considered nontoxic. The elimination of COHb was found to be more rapid in this population of children than reported in other studies.  相似文献   
129.
Ischemia-reperfusion injury to skeletal muscle, following an acute arterial occlusion is a significant cause of morbidity and mortality. The purpose of this study is to examine the role of extracellular calcium in the production of cellular necrosis following a prolonged period of normothermic ischemia. Bilateral canine gracilis muscles were made ischemic for 4.5 to 5 hr. The control muscle had normal blood reperfusion (ionized Ca2+ 1.2 mM). The treated muscle was perfused for 30 min with an oxygenated solution (ionized Ca2+ 0.11 mM) containing free radical scavengers followed by normal blood perfusion. Necrosis was determined by nitroblue tetrazolium staining after 48 hr of reperfusion. Total muscle Ca2+ was measured by atomic absorption spectrometry. Pre- and postischemic muscle Ca2+ levels were similar (2.8 +/- 0.4 vs 3.2 +/- 0.8 nmole/mg protein, n = 13, P greater than 0.1). After 30 min of reperfusion the treated muscle Ca2+ was 2.4 +/- 0.4 compared to control levels of 8.6 +/- 0.8 nmole/mg protein (P less than 0.001). Total tissue calcium returned to normal at 60 min in viable muscle, but continued to accumulate in necrotic tissue. However, the delay in initial muscle Ca2+ influx was not associated with increased overall salvage of muscle 78 +/- 9% vs 77 +/- 8% necrosis, (P greater than 0.1). In conclusion we could not demonstrate a protective effect of reduced extracellular Ca2+ during early reperfusion, and it negated our previously demonstrated beneficial effects of free radical scavengers. It was shown however that the early ability to extrude intracellular calcium was associated with significant salvage of muscle tissue.  相似文献   
130.
Brain dopamine neurotransmission appears to be an important component of the neural pathways involved in the maintenance of intravenous (IV) cocaine self-administration in rats. The effects of a novel partial dopamine agonist, SDZ 208–911, on intravenous cocaine self-administration in rats was studied. SDZ 208–911 at a dose range of 0.025–1.6 mg/kg SC dose-dependently increased the number of lever presses and drug intake in rats exposed to limited (3-h) daily access to cocaine on a continuous reinforcement schedule (0.75 mg/kg per injection). This behavioral profile is similar to that observed following administration of dopamine antagonist drugs and has been hypothesized to reflect a compensatory increase in drug intake due to a reduction of the reinforcing efficacy of the drug, probably because of functional antagonism at the receptor site. These results suggest that dopamine partial agonists may act as functional dopamine antagonists in the face of pharmacologically induced activation of brain dopamine function.  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