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   6977篇
  免费   391篇
  国内免费   43篇
耳鼻咽喉   53篇
儿科学   175篇
妇产科学   151篇
基础医学   989篇
口腔科学   182篇
临床医学   533篇
内科学   1685篇
皮肤病学   137篇
神经病学   866篇
特种医学   205篇
外科学   1134篇
综合类   22篇
预防医学   300篇
眼科学   73篇
药学   444篇
中国医学   16篇
肿瘤学   446篇
  2023年   44篇
  2022年   122篇
  2021年   209篇
  2020年   123篇
  2019年   165篇
  2018年   227篇
  2017年   162篇
  2016年   207篇
  2015年   191篇
  2014年   282篇
  2013年   329篇
  2012年   506篇
  2011年   504篇
  2010年   290篇
  2009年   247篇
  2008年   416篇
  2007年   402篇
  2006年   380篇
  2005年   366篇
  2004年   356篇
  2003年   346篇
  2002年   250篇
  2001年   126篇
  2000年   124篇
  1999年   119篇
  1998年   53篇
  1997年   42篇
  1996年   42篇
  1995年   26篇
  1994年   20篇
  1993年   16篇
  1992年   81篇
  1991年   69篇
  1990年   53篇
  1989年   62篇
  1988年   42篇
  1987年   44篇
  1986年   37篇
  1985年   39篇
  1984年   23篇
  1983年   22篇
  1982年   20篇
  1980年   19篇
  1979年   34篇
  1978年   12篇
  1977年   15篇
  1974年   11篇
  1973年   12篇
  1967年   10篇
  1966年   15篇
排序方式: 共有7411条查询结果,搜索用时 15 毫秒
51.
In this experimental study the authors report an experience in the evaluation of hepatic blood flow with intraoperative echo-Doppler during orthotopic liver transplantation and side-to-side or end-to-side portacaval shunt. Doppler ultrasonography studied the flow of portal vein, hepatic artery and inferior vena cava before the recipient hepatectomy, and after reperfusion during liver grafting. Furthermore echo-Doppler of the portal system was performed to confirm portacaval shunt efficacy. Usually intraoperative Doppler ultrasonography may give informations about the patency of the shunt and regarding the development of early hepatic artery thrombosis during liver transplantation, but often unclear is the exact evaluation of the velocity of the blood flow through the liver. Further experimental studies and clinical evaluations need to find safe parameters and markers of vascular alteration using this superior diagnostic procedure.  相似文献   
52.
53.
Echocardiography has revealed evidence of "subnormal" regional contraction patterns that result from myocardial ischemia and are often accompanied by nonadjacent "hyperkinetic" regions. Whether these regions of hyperkinetic wall motion persist unchanged or revert to normal after coronary artery bypass graft (CABG) surgery has not been studied in humans. Using echocardiography, we evaluated both dysfunctional and normal myocardial regions for changes in segmental wall motion and percent of systolic wall thickening that occurred immediately after CABG surgery in 32 patients. Segmental wall motion analysis before CABG surgery in these patients revealed that 170 (66%) of 256 myocardial segments were subnormal, of which 115 (67%) improved and 102 (60%) returned to normal immediately after CABG surgery. Eleven myocardial segments that were hyperkinetic before CABG surgery returned to normal after CABG surgery. Preoperatively, 162 (63%) of 256 myocardial segments had systolic wall thickening less than 30%, which increased from 11.8% +/- 8.9% to 24.3% +/- 14.3% (mean +/- SD) (P less than 0.01) postoperatively. Conversely, a reverse trend was found when systolic wall thickening was greater than 30% before CABG surgery: thickening decreased from 46.2% +/- 13.8% to 33.4% +/- 14.8% after CABG surgery (P less than 0.01). Thus, we conclude that immediately after CABG surgery, there is a recovery of function in some myocardial segments and a reduction in function in others. Furthermore, we conclude that the semiquantitative assessment of percent of systolic wall thickening is a more reliable (consistent) echocardiographic index of myocardial function compared with the qualitative assessment of segmental wall motion immediately after CABG surgery.  相似文献   
54.
A 44-year-old female presented with Duret hemorrhage due to transtentorial herniation by extradural hematoma as a complication after craniotomy for treatment of spontaneous middle cranial fossa cerebrospinal fluid leakage through the oval window. Brain computed tomography revealed linear hemorrhage in the midbrain and the rostral pons. She awoke after 2 weeks in a coma, despite showing ocular bobbing and bilateral intranuclear ophthalmoplegia. She was discharged from the hospital with minimal neurological defects. Duret hemorrhage is usually fatal, but this case shows that early surgical decompression is the most important factor to avoid the worst sequelae.  相似文献   
55.
Objectives: To determine the quality of life (QOL) after stapes surgery and whether audiological parameters for hearing correlate with specific QOL factors. Design: A retrospective cross‐sectional study. Setting: A tertiary referral centre. Participants: A series of 35 patients who underwent stapes surgery of which three were excluded because they were <18 years of age, chronically or mentally ill, or in a dependant relationship. Response rate was 93% (30/32). Nine were further excluded because they had revision or bilateral surgery, or missing data. Twenty‐one patients were included in this study. Main outcome measures: The Glasgow Benefit Inventory (GBI) was used to evaluate general QOL and the Hearing Disability and Handicap Scale (HDHS) was used as a disease‐specific measure. The Belfast Rule of Thumb and Glasgow Benefit Plot assessed hearing outcomes. Results: Operative success was 86% using the Belfast Rule of Thumb and 95% had closure of the air–bone gap to within 20 dB. 81.8% of patients reported a better overall QOL as surgery. Glasgow Benefit Inventory Social and GBI Physical scores correlated positively with the HDHS speech component (P < 0.05). The duration of hearing loss correlated inversely with the average HDHS score (P < 0.05). Conclusion: The majority of patients report a better QOL as undergoing stapes surgery. Speech impacts on people's physical and social QOL of patients. Quality of life tools, in addition to objective audiologic measurements can provide clinicians with patients’ subjective perspective that helps guide clinical decision‐making and counselling.  相似文献   
56.
BACKGROUND: There is not univocal concordance for using high-dose sequential therapy (HDS) as first-line treatment for aggressive non-Hodgkin's lymphoma (NHL). We designed this study to evaluate the usefulness of HDS followed by high-dose therapy (HDT) with autologous stem cell transplantation as front-line treatment in different subsets of aggressive NHL. PATIENTS AND METHODS: Among 223 patients aged 15-60 years with aggressive, advanced stage NHL, 106 patients were randomized to VACOP-B (etoposide, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin) for 12 weeks (plus HDS/HDT in case of persistent disease) (arm A), and 117 patients to VACOP-B for 8 weeks plus upfront HDS/HDT (arm B). RESULTS: According to the intention-to-treat analysis, the complete response rate was 75% for arm A and 72.6% for arm B. With a median follow-up of 62 months there was no difference in 7-year probability of survival (60% and 57.8%; P = 0.5), disease-free survival (DFS) (62% and 71%; P = 0.2) and progression-free survival (PFS) (44.9% and 40.9%; P = 0.7) between the two arms. Subgroup analyses confirmed that the best results in terms of survival, DFS and PFS were achieved by patients with large B-cell NHL without bone marrow (BM) involvement, independently of the treatment arm. Results were poorer in other categories of patients and poorest in patients with BM involvement. CONCLUSIONS: Aggressive NHL patients do not benefit from upfront HDS/HDT.  相似文献   
57.
Despite the existence of an effective live-attenuated vaccine, measles can appear in vaccinated individuals. We investigated breakthrough measles cases identified during our surveillance activities within the measles/rubella surveillance network (MoRoNet) in Milan and surrounding areas (Northern Italy). Between 2017 and 2021, we confirmed measles virus (genotypes B3 or D8) infections in 653 patients and 51 of these (7.8%) were vaccinees. Among vaccinated individuals whose serum was available, a secondary failure was evidenced in 69.4% (25/36) of cases while 11 patients (30.6%) were non-responders. Non-responders were more frequently hospitalized and had significantly lower Ct values in both respiratory and urine samples. Median age and time since the last immunization were similar in the two groups. Importantly, we identified onward transmissions from vaccine failure cases. Vaccinees were involved in 20 outbreaks, in 10 of them they were able to transmit the virus, and in 8 of them, they were the index case. Comparing viral hemagglutinin sequences from vaccinated and non-vaccinated subjects did not show a specific mutation pattern. These results suggest that vaccination failure was likely due to the poor immune response of single individuals and highlights the importance of identifying breakthrough cases and characterizing their clinical and virologic profiles.  相似文献   
58.
Chest tubes are routinely inserted after thoracic surgery procedures in different sizes and numbers. The aim of this study is to assess the efficacy of Smart Drain Coaxial drainage compared with two standard chest tubes in patients undergoing thoracotomy for pulmonary lobectomy. Ninety-eight patients (57 males and 41 females, mean age 68.3 ± 7.4 years) with lung cancer undergoing open pulmonary lobectomy were randomized in two groups: 50 received one upper 28-Fr and one lower 32-Fr standard chest tube (ST group) and 48 received one 28-Fr Smart Drain Coaxial tube (SDC group). Hospitalization, quantity of fluid output, air leaks, radiograph findings, pain control and costs were assessed. SDC group showed shorter hospitalization (7.3 vs. 6.1 days, p = 0.02), lower pain in postoperative day-1 (p = 0.02) and a lower use of analgesic drugs (p = 0.04). Pleural effusion drainage was lower in SDC group in the first postoperative day (median 400.0 ± 200.0 mL vs. 450.0 ± 193.8 mL, p = 0.04) and as a mean of first three PODs (median 325.0 ± 137.5 mL vs. 362.5 ± 96.7 mL, p = 0.01). No difference in terms of fluid retention, residual pleural space, subcutaneous emphysema and complications after chest tubes removal was found. In conclusion, Smart Drain Coaxial chest tube seems a feasible option after thoracotomy for pulmonary lobectomy. The SDC group showed a shorter hospitalization and decreased analgesic drugs use and, thus, a reduction of costs.  相似文献   
59.
Chicken meat is becoming the most consumed in the world for both economic and nutritional reasons; regarding the latter, the lipid profile may play positive or negative roles in the prevention and treatment of diseases. In this study, we define the state of the art of lipid-based nutritional indexes and used the lipid content and fatty acid profile (both qualitative and quantitative) of breast meat of two poultry genotypes with different growth rates and meat traits. Further, we summarize and review the definitions, implications, and applications of nutritional indexes used in recent years and others of our own design to provide a useful tool to researchers working in the field of meat quality (not only in poultry) to select the most appropriate index for their own scientific purposes. All indexes show advantages and disadvantages; hence, a rational choice should be applied to consider the nutritional effect of meat on human health and for a possible assessment of the most suitable rearing systems (genotype, feeding, farming system or postmortem handling).  相似文献   
60.
OBJECTIVE: The traditional access of perineum for the treatment of the pelvic organ prolapse by vaginal route is probably responsible for the risk of mesh exposure and a longer convalescence. So, endoscopic access to perinemeum needs to be evaluated. PATIENTS AND METHODS: Feasibility study on cadavers. Details of the procedure: opening of the pararectal space by digital dissection first after incision on the level of the posterior commissure. Introduction of an optical trocart to the level of the perineum incision; dissection of pararectal space with optics and CO(2); individualization of the various elements; installation of a transobturator trocart and a transgluteal trocart; dissection of the rectovaginal septum and visualization of the sacrospinous ligament and pudendal nerve. The measured variables were: operational incidents, possibility of creation of working space, dissection of the rectovaginal septum; finally, visualization of the sacrospinous ligament and pudendal pedicle. RESULTS: On the 4 studied cadavers, we could carry out a dissection of pelvirectal space in all the cases. On the 8 pararectal fosses, in all the cases we could carry out a cavity of dissection and to open the recto vaginal septum, visualization of the sacrosciatic ligament and pudendal pedicle was possible in 6 cases out of 8. There were one rectal injury, two vaginal injuries and one lesion of the pudendal pedicle. DISCUSSION AND CONCLUSION: This endoscopic access allows in the majority of cases to see the structures necessary to the realization of a vaginal sacrospinofixation or the installation of posterior mesh without a colpotomy and a traumatic exposure. The incidents are probably due to our inexperience and should disappear in time. The pelvi-perineoscopy is an endoscopic access of perineum which should be evaluated.  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